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August 27

This Last Mars rover

It’s just me, or someone else thinks the Curiosity rover’s cameras are a bit low in resolution terms??
I mean, you can sum all the megapixels of all the onboard cameras and don’t even match the Mpix count of a Nikon d800 and this is just a consumer level camera
All the specs in this page are really “true”? and in this case… Why!? Iskánder Vigoa Pérez 13:45, 27 August 2012 (UTC) — Preceding unsigned comment added by Iskander HFC (talk • contribs)

One reason may be that the rover's instruments were selected and tested back in 2004: Curiosity_rover#Timeline. - Lindert (talk) 13:56, 27 August 2012 (UTC)[reply]

See: Mars rover camera project manager explains 2MP camera choice.--Aspro (talk) 14:00, 27 August 2012 (UTC)[reply]

(ec)Curiosity was designed in 2004 Mars Science Laboratory#History and build by 2008. Aerospace equipment, and particularly equipment that once deployed cannot be replaced, is very conservatively designed. The low-weight, low-power, vibration-tolerant, radiation-resistant, high-thermal-range requirements mean they always lag consumer technology by a long way, in terms of raw numbers. Check Comparison of embedded computer systems on board the Mars rovers and see how much better your phone is than what they run. -- Finlay McWalterჷTalk 14:02, 27 August 2012 (UTC)[reply]

There's also apparently a bandwidth issue - often we only get to see thumbnails until the next day, and some of the images from the first panorama were backlogged for quite a while before finally being transmitted. I guess they have lousy cell phone coverage on Mars. :) Wnt (talk) 14:08, 27 August 2012 (UTC)[reply]

Bandwidth is only a problem if you want the full resolution all the time which you never dare to ask.--Stone (talk) 14:10, 27 August 2012 (UTC)[reply]

The cameras are better than those in the MER rovers. The problem is and always will be that you need flight qualified parts to be allowed to get into a NASA mission. Qualification takes years and adds 3 to 5 zeros to the price and if NASA has to do it on their own it will be a million or several. To get a microchip for space is hard work. A FPGA cost you 50000 $ and than you have a chip capable to do not more than a newest calculator of your kids. Military quality is easy to get, but space qualified makes your life complicated. NASA would simply never consider to fly parts which might harm the success of the mission, even if the cameras are not the most important science tool they are the most important PR tool. --Stone (talk) 14:10, 27 August 2012 (UTC)[reply]

This article [1] discusses the issue. Acroterion (talk) 14:39, 27 August 2012 (UTC)[reply]

The CCD KAI-2020CM for MER and the Mitel (DALSA) doi:10.1029/2003JE002070 for MSL are not 2012 style, but still they were the best choice.--Stone (talk) 14:57, 27 August 2012 (UTC)[reply]

Another thing to consider is that consumer cameras are lower-resolution than they appear. A consumer camera uses a Bayer filter pattern for color: this gives you about N/2 megapixels of brightness resolution, and only about N/4 megapixels of color resolution, eg. a 16MP camera only has 8 megapixels of brightness resolution, and 4 megapixels of color resolution. The Mars rover cameras use broad-spectrum sensors and a collection of single-color filters, so a 2 megapixel sensor gives 2 megapixels of color resolution. --Carnildo (talk) 00:02, 1 September 2012 (UTC)[reply]

Stopping neutrinos

Since neutrinos have mass, does that mean they could, in theory, be slowed or even stopped relative to some stationery observer? Likewise, our article on photons mentions that they could as well have a very small amount of mass. If that turned out to be the case, would that mean that even light could be stopped? Goodbye Galaxy (talk) 15:26, 27 August 2012 (UTC)[reply]

Light is slowed, by literally every material it passes through. See Refractive index. Individual photons always travel at the speed of light, but this is not the same thing as the speed of the light (as a bulk phenomenon) itself. It sounds like you understand this, but I just wanted to clarify incase you, or others reading, don't. The speed at which light (as a phenomenon) travels depends greatly on exactly what is meant by the words "speed", "light" and "travels". --Jayron32 15:32, 27 August 2012 (UTC)[reply]

Yes, slow neutrinos are a possibility, but you can't really keep them in one place because of the uncertainty principle and the lack of any way to confine them (since they interact so weakly with everything else).

The standard model predicts that the photon is exactly massless, but experimentally you can never prove the mass is exactly zero; you can only establish better and better upper bounds. -- BenRG (talk) 15:56, 27 August 2012 (UTC)[reply]

And what if we presuppose that the photon has a slight mass? Goodbye Galaxy (talk) 16:55, 27 August 2012 (UTC)[reply]

In that case, you could create a Bose-Einstein condenstate of consisting of photons. The macroscopic description would be given in terms of a "classical" Proca action. Count Iblis (talk) 17:06, 27 August 2012 (UTC)[reply]

Would that be any different from an ordinary standing electromagnetic wave? Naively looking at the B-E transition temperature, it goes to infinity as the mass goes to zero, implying that this is the normal state for photons anyway. -- BenRG (talk) 17:53, 27 August 2012 (UTC)[reply]

Like the neutrino it would be hard to keep it in one place. You could confine it in a mirrored box, but you can confine a massless photon in a mirrored box too. Having a very tiny mass is not much different from having no mass at all. -- BenRG (talk) 17:53, 27 August 2012 (UTC)[reply]

Does the quantum foam (or Higgs field) slow observed photon velocities in vacuum to slightly less than the true speed of light? Hcobb (talk) 00:24, 28 August 2012 (UTC)[reply]

No, not in the standard model and not as far as experiments can tell. The vacuum is Lorentz invariant and the only Lorentz invariant thing it could do to the photon is give it a Lorentz invariant mass, so your question is equivalent to asking whether the photon has mass. In the standard model the photon is massless by construction: not all of the electroweak symmetry is broken, and the particle associated with the unbroken part is called the photon. I don't know what the story is in beyond-standard-model theories. -- BenRG (talk) 03:09, 28 August 2012 (UTC)[reply]

Finding Electric Field Magnitude and Direction at a Point Charge

Given three point charges positioned in a plane at the vertices of an equilateral triangle, is it possible to find the electric field magnitude and direction at the position of one of the point charges as a function of the charges of the three points and the length of the sides of the triangle? For example, given point charges with specified electric charges at points ABC located at the vertices of equilateral triangle ABC with side length l, could I determine the electric field magnitude and direction at point A?

—Dromioofephesus (talk) 17:02, 27 August 2012 (UTC)[reply]

No. The electric field direction is discontinuous at A, and the magnitude is singular at A. Red Act (talk) 20:01, 27 August 2012 (UTC)[reply]

Classical electromagnetism does not really admit of point-charges, as these would have infinite energy and therefore infinite mass (see classical electron radius). At any of the vertices, you can however calculate the contribution to the E-field from the point-charges at the other two vertices - and this immediately gives you the force on each of the three point-charges (under the assumption that a point-charge does not exert a force on itself). --catslash (talk) 00:16, 28 August 2012 (UTC)[reply]

How come my Prickly Pears won't bloom?

A few years ago I transplanted some Opuntia humifusa (Eastern Prickly Pear) from one property to another. They bloomed yearly at the old location. The six or so lobes I moved to the new location are doing spectacularly, and there are about 30 lobes now. They are in a well drained partially sandy area with strong direct sunlight all day until June, when they would normally bloom, and about 6 hours of direct sunlight once the oaks leaf out and partially shade them in the late afternoon. (They usually bloom around June 1, so I don't think the leaf cover is at all significant.) I have only had one single flower in all that time, and it was while the plant was still in the pot I used to move it in, before it was put back in the ground. The same with one I keep indoors. I planted it as a cutting and it bloomed once in the pot, and never since. Any suggestions as to why this may be and what to do about it? Google searches have been of no use at all. Thanks. μηδείς (talk) 18:12, 27 August 2012 (UTC)[reply]

FWIW (and I have flowered quite a few Opuntiae) I think the most likely problem is the roots are unconstrained and the soil is too rich, a bit like with (completely unrelated) figs. They tended to flower for me when they had no option to grow instead. I suggest stress them a bit; limit the roots and ensure the soil is a bit barren. Or even just cover the soil so they get less water. --BozMo talk 18:21, 27 August 2012 (UTC)[reply]

It did occur to me that they might need stress. The interesting thing is that the potted one indoors is very constrained and gets water only when it starts wilting, but still hasn't bloomed in three years. The ones outdoors may be a bit hard to stress, since they are going to receive a lot of water unless there is an east coast drought. Are you suggesting they will perhaps bloom once they get crowded? μηδείς (talk) 18:40, 27 August 2012 (UTC)[reply]

I would also suggest that they are more likely to bloom when crowded. Think of it in terms of investment in sexual reproduction vs. clonal growth. If it is easy to spread vegetatively, why invest precious resources in low-odds sexual reproduction? You could install a bed-guard around the perimeter like those used in landscaping, or even just increase competition by planting a different plant all around the perimeter. Lastly, the easiest thing might be to sever the below-ground connections, so that all the individuals in the middle are competing against their neighbors (if they are connected, competition between ramets is much much less). SemanticMantis (talk) 19:17, 27 August 2012 (UTC)[reply]

Chilling requirement? Count Iblis (talk) 19:20, 27 August 2012 (UTC)[reply]

One of my undergrad majors was in Biology with a focus on plant ecology, so I grok the above comments. I have also found a suggestion that 0/10/10 fertilizer helps with flowering, which is the only solution that seems doable without digging up the bed. The chilling requirement might be relevant for the indoor plant. It doesn't freeze, but it is in an unheated and unlit (except for sunlight) room that I use to force my Poinsettias to bloom. There would be no trouble putting the potted plant outside. Unfortunately we can't expect results till next June, long after the Mayan apocalypse. μηδείς (talk) 19:31, 27 August 2012 (UTC)[reply]

PS, this is obviously a clone of a plant that did bloom well before, and which was not really crowded, even by itself. The prior soil was a bit more sandy, and it was never watered. (These plants are wattered occasionally and indirectly, but not a lot.) The old soil probably had a much higher salt content (it was occasionally flooded by the ocean during storms). Perhaps covering the plants in a few inches of beach sand will help? μηδείς (talk) 19:37, 27 August 2012 (UTC)[reply]

Maybe beach sand will help. Another thing to keep in mind is the age of the genet. Some plants, especially succulents, will only bloom once they've reached some ratio of above ground/below ground mass, or even a critical threshold of total biomass. So, assuming you didn't also start the last colony from a few cuttings, I suspect doing nothing will generate plenty of blooms within a few years. SemanticMantis (talk) 14:40, 28 August 2012 (UTC)[reply]

Light source measurement in CRI/Ra

What does the "Ra" part of CRI/Ra stand for? Electron9 (talk) 22:29, 27 August 2012 (UTC)[reply]

The R seems to stand for "rendering", but the "a" I'm unsure of. According to [2] "General Color Rendering Index R_a" contrasts with "Special Color Rendering Indices R_i" (apparently the "i" is for index). Perhaps "a" was just chosen as the first variable in the alphabet (were there R_b and R_c values initially, too ?). StuRat (talk) 23:00, 27 August 2012 (UTC)[reply]

Ra = the general color rendering index. It's an average value, hence the "a." Zoonoses (talk) 03:45, 29 August 2012 (UTC)[reply]

August 28

Symmetries of the Universe

The book, Concepts of modern mathematics by Ian Stewart in its chapter on symmetry, states that:

In mathematical physics, laws like the conservation of energy follow from certain (postulated) symmetries of the universe.

My questions are,

1)What are those postulated symmetries?

2)How does the law of conservation of energy follow from them intutively speaking?

Thanks--Shahab (talk) 05:34, 28 August 2012 (UTC)[reply]

See Noether's theorem, which should explain all about the relationship between conservation laws and symmetry. --Jayron32 05:40, 28 August 2012 (UTC)[reply]

Was the flies in Autstalia tamed so that they mainly feed on plants but not trash?

I have heard in a Chinese article that the Australians put a fly on the $50 bank note, and the reason is that they tamed by cleaning every dirty place and forced the flies to change their diets into plant nectars and no longer becoming a health hazard. Is that ever possible? There can be animal feces everywhere in the wild and I think just cleaning trashes in cities will not affect the flies’ diet much.--211.162.75.202 (talk) 06:05, 28 August 2012 (UTC)[reply]

I am looking at an Australian fifty-dollar note. Wikipedia's article about it says nothing about flies. I can't see a fly anywhere on it, so it sounds like the Chinese article has got it wrong. I have never heard anything about every dirty place in Australia being cleaned to the extent that flies changed their dietary habits. Dolphin (t) 06:34, 28 August 2012 (UTC)[reply]

I suspected that this weird post was from a troll, but as he gelocates to Guandong China, and the linked articles is a Chinese site, here is a definitive answer:-

1. I am an Australian, located in Australia;

2. I have an Australian $50 note in front of me right now;

3. There are no flies on this note. It only has pictures of famous Australians, a Goverment building, and drawings of what appear to be sheep shearing equipment.

4. Flies were once quite a problem in the Australian city in which I live, but the authorities about 18 or 20 years ago changed everybody over from using galvanised iron rubbish bins to specially designed rigid plastic rubbish bins (known as "wheelie bins"), as well as using better landfill practices. These plastic bins have lids that make a good seal on the bin, so the flies can't get at the rubbish. This produced a marked drop in the fly population, making it possible to eat outside for the first time. Since then, the flies have evolved into a more resourcefull and hardy sort, and numbers have increased a little, but they remain not a problem. It is also normal practice to seal food rubbish in palstic bags before placing in the bin, making it very difficult for flies, and eliminating any smell.

Incidentally, most local goverments have passed ordinances making it an offence to leave faeces (e.g., from pet dogs) in place on the ground, but this is to make footpaths and parks pleasant for walkers and joggers, not to control the fly population. Wickwack124.178.52.176 (talk) 06:43, 28 August 2012 (UTC)[reply]

I guess the 2 dollar coin has the Southern Cross which could look like flies to the easily confused. Sean.hoyland - talk 06:52, 28 August 2012 (UTC)[reply]

The fifty-dollar note also has the Southern Cross - in the transparent window. These five stars might look like splattered flies, but they don't look much like live ones. Dolphin (t) 07:10, 28 August 2012 (UTC)[reply]

They don't look anything like splatted ones either - they are way too precisely drawn uniform and delimitted 7-pointed stars, with one 5-pointed one. Wickwack124.178.52.176 (talk) 10:15, 28 August 2012 (UTC)[reply]

There's been a reduction in the fly population in Australia over the past 30 years or so due to the introduction of carefully chosen dung beetles. HiLo48 (talk) 07:21, 28 August 2012 (UTC)[reply]

But I should also assure the OP that we haven't eliminated the fly problem. In parts of the country, at certain times of the year, little bush flies can still be very common, and March flies, which seem to have trouble reading the calendar and appear in far more months than March, can still be bloody pests! HiLo48 (talk) 09:13, 28 August 2012 (UTC)[reply]

Dung beetles are only relavent in farming areas. Most Australians live in cities - where cattle dung is not available. Wickwack124.178.52.176 (talk) 10:12, 28 August 2012 (UTC)[reply]

As I understand it (and I don't claim to be an expert) the reduction of flies on country areas is reflected in city areas too. Flies travel on the wind. We couldn't have had all our modern outdoor eating areas 40 years ago. HiLo48 (talk) 10:23, 28 August 2012 (UTC)[reply]

We couldn't have them 20 years ago. It was the wheelie bins that fixed it, and was the justification for the cost. Flies might travel on the winds, but in Perth, we are right in the trade wind zone, and on the coast. Those poor flies 20 years ago must have come from Africa 6000 km away then. Wickwack124.178.52.176 (talk) 14:52, 28 August 2012 (UTC)[reply]

Fair comment. I'm in Melbourne where the hot summer winds come from the north, and that's where all the flies are. HiLo48 (talk) 20:40, 28 August 2012 (UTC)[reply]

Thanks for the information above. Is it true that fly never ever appeared on any Australian notes--the ones being used now and the previous ones?--211.162.75.202 (talk) 07:28, 29 August 2012 (UTC)[reply]

Yes, it is true. Dolphin (t) 07:36, 29 August 2012 (UTC)[reply]

The CSIRO released sterile blowflies in the 70s to reduce the fly population[3] is that what you are thinking of? Images of Autralian banknotes are available at this article--Surturz (talk) 05:07, 30 August 2012 (UTC)[reply]

OK, the old $50 note has a picture of Ian Clunies Ross, who among other things developed an immunization for dogs to protect against the dog-tick. Drawing a long bow, but maybe that factoid got mangled in translation? --Surturz (talk) 05:15, 30 August 2012 (UTC)[reply]

The resolution of reality

Hi a number of thoughts have just swept through me and I have to ask this multi-pronged question. Assuming what we see is made up of zillions of pixels, what is the resolution of reality (let's say per cubic metre)? When do you think audiovisual equipment will be able to catch up with the processing power and resolution needed to create an (holographic?) image identical to our eye's optical mechanism? Then, finally, do we dream in the same resolution as what we see? If so, does this imply that our brain has enough computing power to interpret stored images in the same way it interprets reality passed on from the retina? Sandman30s (talk) 15:06, 28 August 2012 (UTC)[reply]

Some basic starting comments; you only see very good resolution on a small area of focus at any moment. Your brain interprets a whole load of things in different places (so you are much more sensitive to movement and change than to other details); "processing" is therefore highly selective. Also dreams are mainly symbolic, rather than pixelated. --BozMo talk 15:11, 28 August 2012 (UTC)[reply]

The basic reception equipment in each eye is about 120 million rods (brightness and darkness) and 7 million cones (color). These don't really map onto "pixels" — the eye doesn't work the way you are describing it, it's not a simple photoreceptor circuit — but it gives you some idea about the richness of human visual perception. Fooling eyes is in some ways a lot easier than that — distance matters a lot, as does lighting. We can already do plenty of things that would fool the human eye at a distance. What is trickier is when someone is looking at something very close up. --Mr.98 (talk) 17:07, 28 August 2012 (UTC)[reply]

It isn't the eye you have to fool, it's the brain. The visual system also doesn't work like a camera, not so much because there aren't pixels, but because there's nothing at all like film. The modern digital camera is a better analogy for the human visual system because, just like you need a computer program to translate the data file that contains the image before it looks like an image, you need the brain to interpret the data from the eyes in order to understand what the eyes are seeing. Just as playing around with the code on said computer file will drastically change the picture captured by the camera, the visual perception system is easily fooled. See Visual perception. It is quite easy to devise optical illusions which don't fool the eye at all. The eye records the same visual data, but the data is carefully constructed as to fool the brain. The brain does all sorts of processing to make sense of our three-dimensional world, and not all of it is so straight forward. Gestalt psychology is one perspective that deals some with how the brain visually processes incoming data. It isn't a universally accepted explanation, but it is insightful in places. --Jayron32 17:41, 28 August 2012 (UTC)[reply]

What our brains perceive through our senses is a very tiny part of what information is actually out there in the electromagnetic spectrum. And that's not including dark matter and energy. So the "resolution of reality" concept is flawed: if we answered that question according to the capacity of the human brain, it wouldn't be a representation of reality itself, merely a representation of the human perception of reality - and there's a vast difference. --TammyMoet (talk) 18:08, 28 August 2012 (UTC)[reply]

Would entities exist without minds to distinguish them?

The free will discussion above is about to be archived, but there is still a pending question, so I have continued it here.

prior free will discussion for context

The following discussion has been closed. Please do not modify it.

A machine with free will (arbitrary break 1)

We are all mathematical algorithms, there is no such thing as a physical universe, all that exists is math. Qualia are computational states of algorithms. Count Iblis (talk) 22:38, 24 August 2012 (UTC)[reply]

We are not mathematical algorithms at all, there is no such thing as math: all that exists is the physical universe.... AndyTheGrump (talk) 22:44, 24 August 2012 (UTC)[reply]

The truth, as usual, lies somewhere between those 2 extreme positions. -- ♬ Jack of Oz ♬ ^{[your turn]} 22:49, 24 August 2012 (UTC)[reply]

No. The truth is that all that exists is the physical universe by definition. To say otherwise is farcical. 203.27.72.5 (talk) 23:21, 24 August 2012 (UTC)[reply]

Not to spoil the fun by throwing in a reference (which suggests this should really be running on the humanities desk, or maybe misc, since we're well into philosophy and logic), but try some Wittgenstein:

1 The world is all that is the case.

1.1 The world is the totality of facts, not of things.

1.11 The world is determined by the facts, and by their being all the facts.

1.12 For the totality of facts determines what is the case, and also whatever is not the case.

1.13 The facts in logical space are the world.

1.2 The world divides into facts.

1.21 Each item can be the case or not the case while everything else remains the same.

Tractatus Logico-Philosophicus. 86.169.212.200 (talk) 21:05, 25 August 2012 (UTC)[reply]

Correct me if I'm wrong, but haven't later philosophers rejected this position - including Wittgenstein himself? AndyTheGrump (talk) 04:15, 26 August 2012 (UTC)[reply]

It is still true that math exists. To say otherwise would cause great distress to the workers at the Mathematics Reference Desk. And it is still true that not everything is math. And it is true that not everything is encapsulated in "the physical universe". For example: ideas, thoughts, feelings, mathematical concepts ... -- ♬ Jack of Oz ♬ ^{[your turn]} 05:09, 25 August 2012 (UTC)[reply]

What is an thought besides a collection of electrical signals firing along synapses in your brain? Is that not physical? --Jayron32 05:15, 25 August 2012 (UTC)[reply]

Let me just point out that 203.27's supposed "definition" of the universe pre-supposes that everything in the universe is physical. That is just about the most unscientific and prejudiced and close-minded position one could possibly take. It's also not a universe that I have any knowledge or experience or understanding of. -- ♬ Jack of Oz ♬ ^{[your turn]} 10:11, 25 August 2012 (UTC)[reply]

I'll note by my personal crazy model above, everything actually isn't math - math is deterministic, and the point of the causality violation is to create an opening for something outside the known universe, beyond our ability to examine and perhaps to comprehend, to potentially affect it. The free-willed decisions actually all become boundary conditions of the universe. Wnt (talk) 12:50, 25 August 2012 (UTC)[reply]

It is a World 2 object in Popper's three worlds ... besides being a collection of electrical signals firing along synapses in your brain. To put it that way is true, but reductionist - other collections of electrical signals firing in your brain might not be thoughts, but smells, or migraines, or fits, so a higher-level description is commonly more meaningful. (Wait, all those things are probably world 2 objects as well. Damn. Still, a thought is a thing in its own right, an emergent thing.) Card Zero (talk) 15:40, 25 August 2012 (UTC)[reply]

You are correct- things like mathematical and sciontific concepts are not part of the physical universe by any menes.Aliafroz1901 (talk) 10:45, 25 August 2012 (UTC)[reply]

Or maybe they are, the jury is still out, but the effort put into discussions like this are probably better put into articles like physicalism. Sean.hoyland - talk 11:20, 25 August 2012 (UTC)[reply]

Yeah, but then we'd need sources. Philosophy is like feces or potential employees - everyone has excess to give away, but who wants to consume it? Wnt (talk) 12:46, 25 August 2012 (UTC)[reply]

Like I said above, everything is math. When we assume that what we experience is a physical world that is somehow more than a purely mathematical entity, we actually don't know what that fundamentally is. So, assuming that a physical world that is different from pure math exists is religion, it isn't science. Most scientist do believe in a physical world, but then more than a century ago, most scientists were deeply religious people.

If you feel pain, then this is not fundamentally caused by electrical signals, it is caused by the computation your brain performs. A huge analogue computer that would run the same algorithm as your brain is running and processing the same data would experience the same pain, even though it consists of gears. Count Iblis (talk) 19:10, 25 August 2012 (UTC)[reply]

So, if nothing physical exists then what's running the algorithms? 203.27.72.5 (talk) 20:20, 25 August 2012 (UTC)[reply]

The algorithms are not really run, they only exist in a mathematical sense. All possible algorithms thus exist. One of these algorithms is the formal description of your brain at this moment when you read this part of the sentence, one slightly different algorithm is the formal description of your brain at this slightly later moment when you read this. Count Iblis (talk) 04:07, 26 August 2012 (UTC)[reply]

To answer the original question, it is easy to create a machine with free will as it is conventionally defined. The creation process is called Procreation. --BozMo talk 21:34, 25 August 2012 (UTC)[reply]

Our brains can take in information and we can use that information — plus our existing world views, emotional states, and what have you — to make deliberative decisions about our actions. We can weigh possible outcomes, things we desire or desire to avoid, and come to conclusions. We can even come to very unintuitive or unexpected conclusions. We can use information, values, and empathy to decide what sorts of activities we agree we feel comfortable undertaking, and those which we would desire to never undertake. To me, this is as much as anyone seems to ever really mean by "free will" — I don't actually see debates about causality and materialism to be germane to the topic. Even setting aside the question of what consciousness really is — we have no clue, and it is a mighty significant thing to know nothing about when talking about such things — to me all anyone really wants to know is, "Are we responsible for our actions? Do we actually make decisions?" We feel that we are. We act like we are. Very few people who are not looking to excuse their prior actions ever seem to really ascribe to the philosophy that they are completely out of control of their own actions. That strikes me as pretty "good enough." I am not quite willing to say that my consciousness is totally illusory — it feels pretty "real" to me, and though that is just one datapoint, over time I've come to believe (when I ignore all of the postmodernism and language-games talk that was drilled into me by professors and try to evaluate it in a completely honest, personal way) that it's actually a pretty significant datapoint.

But moving to the meat of the original question: I see no a priori reason to think that we could not imbue a machine with the same faculties as a human brain. This would include whatever appears to be a component of "free will", as defined above. How to do this, I have no idea, and I doubt anyone else alive does either. The human brain is still virtually terra incognita when it comes to understanding the physical basis of consciousness. I suspect we're still a long way off from making sense of it. We probably need to make sense of what makes us us before we can make other things us. --Mr.98 (talk) 01:54, 26 August 2012 (UTC)[reply]

Bodies (hylomorphic substances) and those things that exist in relation to bodies (aristotelian categories) exist. Mathematics doesn't exist by itself. If it did, would it be in base two? Or base ten? Or base e? The assertion is absurd. Mathematics is a perspective on reality that observes quantity but ignores quality. Consciousness is not a thing, or a body. Consciousness is a relationship, a sort of harmony that exists between certain types of bodies, in respect to their forms, and mathematics is a complex sort of such relationship. To insist that mathematics as such existed back when there were only fish or only molten planetoids or dense clouds of plasma makes as much sense as insisting that documentary films did. μηδείς (talk) 02:18, 26 August 2012 (UTC)[reply]

Medeis - I am not sure I completely follow what you mean by "mathematics doesn't exist by itself". Your analogy with documentary films (which I think we can agree have a form of existence) seems to imply that mathematics exists in some sense of "exists", just not "by itself". Is that correct ? If so, can you clarify what "by itself" means by giving an example of something that does "exist by itself" ? Gandalf61 (talk) 09:00, 26 August 2012 (UTC)[reply]

Fundamentally, existence just is what it is. We use various concepts to manipulate it mentally, allowing us to act effectively in it. We view reality fundamentally as consisting of entities, "things", which exist in themselves. We can say, there is a tree, there is a person, there is a rock. Entities have attributes (qualities) and exist in certain relationships. A ball can be red, can be round, can have all sorts of attributes. But we don't talk of there being a red, or there being a round, walking down the street, apart from a red or round thing. Attributes exist, but they don't exist in themselves, but rather of entities.

Likewise relationships. To be aware of, to be as big as, to be the father of, these relationships exist between entities (and in more complex ways, like analogies, which are relationships between relationships, and so on.) Again, we do not (unless we lose focus) talk about an "aware of" (i.e., a consciousness) or an "as big as" walking down the street independent of any entity. Don't get me wrong, redness doesn't exist any less than ballness or nearness. They all exist. An entity is the sum of its attributes and its relationships through time. It is also the sum of its substance (or "parts") and of its form (or "shape").

All of these things are real. Sweetness is real--it just doesn't exist on its own, or separate from a sweet thing and a creature capable of tasting it. Sweetness is a relational attribute, not a thing, not a part of a thing, not an atom. See Aristotelian category for some of the various ways in which we say things exist.

Mathematics is a complex set of ideas (which are relations, not entities) about quantitative relationships. Mathematics is quite real, but it is an abstraction that exists as a relation between conscious entities and their environments. And the form in which we express those relations is to some extent arbitrary. We can cut an apple in two equal pieces (the same as 10 equal pieces in base two) and talk about 1/2 of it or 50% of it. The thing itself is what it is, the mathematical description of it is just as real, but real as a relation between us as conscious measurers and the entities in question.

Humans are quite adept at abstraction. We can ignore our senses for the moment and picture everything in terms of its mathematical description (pythagorean idealism) or in terms of atoms and void (naive/reductive materialism) or in terms of minds and Ideas (Platonism). And we might in flights of fancy even be tempted to say that only numbers or particles are real. But without our direct awareness of entities and attributes (the ability to read the red hand on the meter of the geiger counter) we would have no contact with them. Numbers and particles and the like cannot claim to be real if the perceptions they are abstracted from are not. μηδείς (talk) 19:20, 26 August 2012 (UTC)[reply]

Suggested reading in order of difficulty: Ten Philosophical Mistakes by Mortimer Adler, Introduction to Objectivist Epistemology, 2nd Ed. by Ayn Rand, An Introduction to Logic by H. W. B. Joseph μηδείς (talk) 19:46, 26 August 2012 (UTC)[reply]

Okay, so when you say "We view reality fundamentally as consisting of entities ...", does this mean that the distinction you are making between entities, attributes and relationships is a function of how we (i.e. human beings) perceive reality, not something that is inherent in reality itself ? So categorising a tree as an entity is a subjective judgement, not an objective fact ? That makes sense to me because singling out the tree rather than its branches, leaves or cells, or the forest of which it is a part, or the acorn from which it grew, or the planks which it will become is clearly a somewhat arbitrary slicing of reality. Gandalf61 (talk) 11:57, 27 August 2012 (UTC)[reply]

Very pertinent question. Remember that consciousness is a relationship between a certain type of being and its environment. If we were beings of a vastly different scale, galactic or atomic in size, we would obviously have different ways of perceiving reality. If one takes the consensus view of quantum mechanics, it is unlikely we would perceive atoms the way we as humans perceive billiard balls. (I don't want to endorse any theory a priori here, philosophy doesn't entitle us to speculate on facts that only science can discover.) If we were "atomies" we would not perceive trees directly, or likely even color, given the scale difference. But our scientists might discover these things in the way that ours have discovered radio waves and that the Milky Way is a spiral galaxy. Whether or not "atomies" would apprehend things in terms of entities and events is a matter of speculation.

But the fact that we perceive things that way is not subjective, so much as relative, and relative in an objective way. Humans have an objective nature--their brains and sense organs have a definite nature; they work in a definite way. Reality has a definite nature--it is what it is. Our consciousness of reality is veridical if it conforms to the nature of our sense organs and of reality. We can open our eyes and carefully observe things, or stick our fingers in our ears and hum, or have our tea-leaves read instead of our MRI. The fingers-in-the-ears or the tea-leaves strategies are the subjective ones. They are the ones where the subject creates the contents of its consciousness without relation to the facts of reality. The people who open their eyes and see reality are the ones getting objective knowledge--even if one man is colorblind, and the other not, the statement "this is the way these things look to me in these circumstances" is objectively true for both.

The mistake would be to insist that the concepts of entity and attribute and relation are intrinsic to reality. It would be just as presumptuous to say those concepts exist in reality as its ultimate fundamental makeup without relation to our consciousness of reality as it would be mistaken to say those concepts exist only in our minds without relationship to reality. For most of the history of philosophy people have insisted on an a priori metaphysics. "Ultimate" reality is: earth, air, water and fire; atoms and void; number and harmony; spirit and clay. That is substituting metaphysics for science. And it means every scientific discovery threatens to overthrow your philosophy. Things are what they are. Our concepts are useful if they conform to our means of comprehending reality. Concepts like substance and form; entity, attribute relation (and event, and so forth) are invaluable. Most philosophical mistakes result from their misapplication. Consciousness is not an entity. Evil is not a substance: "It contains pure evil!") Ideas are not things. But neither are these things unreal.

On the nature of concepts and objectivity as relational, read Introduction to Objectivist Epistemology. On the ubiquity and danger of category mistakes read Ten Philosophical Mistakes]. μηδείς (talk) 16:52, 27 August 2012 (UTC)[reply]

Okay, so without the relationship that we call conciousness (and, specifically, human conciousness or something very similar to it) there can be no entities that we call trees or rocks, in the same way as there can be no mathematics without conciousness. Gandalf61 (talk) 09:13, 28 August 2012 (UTC)[reply]

The notion that the reality of the universe could exist purely as mathematics is, well, disturbing for a number of reasons, not the least of which is, that for every irrational number A.BCDEFGHI..., there are truncated versions A.0, A.B, A.BC, A.BCD, etc. So for every instant in the cosmos when you're sitting there reading this message the way you think you should be, there are an infinite number of instants where you're sitting there missing your feet, legs, waist ... and an even "larger" infinite number where they're replaced with some other thing, cat bodies, refrigerators, Cthulhean monsters. But I think that because the existence of a single perfect, "properly formed" moment in space and time is so infinitely unlikely amid the mass of numbers, and we perceive (I hope) such an instant presently, it is therefore equally improbable that this model of the formation of reality is truth. Wnt (talk) 10:28, 26 August 2012 (UTC)[reply]

That's (sort of) an analogue if the Boltzmann brain problem for the mathematical universe. But then all known physical theories of the universe suffer from the same disease. However, I have found a solution to this problem for the case of the mathematical multiverse, which is natural, not some ad hoc fix, which doesn't have an analogue for "physical theories". Count Iblis (talk) 15:20, 26 August 2012 (UTC)[reply]

I'm not familiar with Boltzmann brain, but the "paradox" they describe in that article is easily solved; I've ranted on about it here half a dozen times before. We are always in a state of relatively low entropy because we always keep moving the goalposts. The universe apparently gets larger and cooler in very rough proportion to its age, and the time its residents are willing to wait for "interesting events" expands in like proportion. From the subjective point of view, the most important laws of physics are always changing. Someday protons will be exotic particles found only in cutting edge laboratories, but the people studying them will be made out of "neutrino nuggets" or something, tiny insubstantial particles that take billions of years for one tick of the clock to pass. But I digress, and admittedly, on a favorite crank idea. Wnt (talk) 03:50, 27 August 2012 (UTC)[reply]

http://arxiv.org/abs/1202.4545

"The Relativity of Existence Stuart Heinrich (Submitted on 21 Feb 2012 (v1), last revised 23 Aug 2012 (this version, v2)) Despite the success of modern physics in formulating mathematical theories that can predict the outcome of experiments, we have made remarkably little progress towards answering the most fundamental question of: why is there a universe at all, as opposed to nothingness? In this paper, it is shown that this seemingly mind-boggling question has a simple logical answer if we accept that existence in the universe is nothing more than mathematical existence relative to the axioms of our universe. This premise is not baseless; it is shown here that there are indeed several independent strong logical arguments for why we should believe that mathematical existence is the only kind of existence. Moreover, it is shown that, under this premise, the answers to many other puzzling questions about our universe come almost immediately. Among these questions are: why is the universe apparently fine-tuned to be able to support life? Why are the laws of physics so elegant? Why do we have three dimensions of space and one of time, with approximate locality and causality at macroscopic scales? How can the universe be non-local and non-causal at the quantum scale? How can the laws of quantum mechanics rely on true randomness?"

Count Iblis (talk) 23:33, 26 August 2012 (UTC)[reply]

You don't need to write a paper to explain why existence exists. It takes just six words: There was nothing to prevent it. μηδείς (talk) 02:23, 27 August 2012 (UTC)[reply]

Wow, all this, and nobody's yet pointed out that we do have a very thorough article called Free will. Red Act (talk) 03:39, 27 August 2012 (UTC)[reply]

LOL, we can put this discussion into BJAODN. ibicdlcod (talk) 15:03, 27 August 2012 (UTC)[reply]

Okay, so without the relationship that we call conciousness (and, specifically, human conciousness or something very similar to it) there can be no entities that we call trees or rocks, in the same way as there can be no mathematics without conciousness. Gandalf61 (talk) 09:13, 28 August 2012 (UTC)[reply]

Briefly, things are what they are. So before minds existed, there were still what we call things. We can see that this must be the case because the universe evolved from the big bang and life evolved to produce animals and minds and mankind. What couldn't exist before minds existed was the mental categories of things, such as entities versus attributes, in abstraction. Mathematics is abstraction. All of the mathematical relations that held between things before there were minds to identify them still held. But they held in reality itself, not as numbers, which are concepts--symbols, in effect--that we use to grasp those proportions. Consider the problem of finding the longest piece of dry spaghetti. You can get a ruler and measure each one according to some unit and identify the largest number corresponding to the length of one of the pieces of spaghetti. Or you can stand them in a glass with a flat bottom, and the one that stands tallest is the longest. The first means requires a mind that does math. The second doesn't. (Although obviously glasses and spaghetti are products of beings with minds--but this is just an example.) The result is the same in each case, because the underlying reality is the same. But the math requires a mind. To say that the math itself is the underlying reality is at best a mind game. μηδείς (talk) 17:13, 28 August 2012 (UTC)[reply]

A vital read in this discussion (which is much more about philosophy than science, but whatever) would be Existence precedes essence, which discusses the philosophical conundrum of which comes first: whether something exists first and aquires meaning after it existance, or whether something needs to be defined before it says it exists. There are differing schools of thought as to which makes sense. --Jayron32 17:34, 28 August 2012 (UTC)[reply]

Thanks, Jayron. I have been wondering if there was an article like that. μηδείς (talk) 19:12, 28 August 2012 (UTC)[reply]

μηδείς, how do you know that there was a time when consciousness did not exist? if it does not fit in the physical universe now, then I would assume that it never did.165.212.189.187 (talk) 19:31, 28 August 2012 (UTC)[reply]

So far as we understand scientifically (and not imagine), minds and consciousness are faculties and properties of a certain type of living being. Based on quite a bit of evidence, I am willing to attribute consciousness to animals as simple as all birds and mammals and even octopuses, if not fish. But I have no evidence that there was consciousness when there were only single-celled organisms, and absolutely not before life existed. One has to provide prima facie evidence for something, else it is just an arbitrary assertion. As Hitchens asserts, "What can be asserted without proof, can be dismissed without proof." μηδείς (talk) 20:26, 28 August 2012 (UTC)[reply]

Absence of evidence is not evidence of absence... --TammyMoet (talk) 08:14, 29 August 2012 (UTC)[reply]

If you cannot even remotely explain consciousness with physics then how can you say that consciousness is entirely contained in our physical world? We know more about black holes than we do about what is between our ears. I love how physicists freely throw around ideas like "other universes in other dimensions" when talking about black holes or dark energy/matter way out there in space, yet when it comes to something so close to us as our consciousness physicists get constipation of the brain. occams razor could easily explain that those other dimensions thier math is probing/detecting could be our consciousness or the past or future.165.212.189.187 (talk) 14:19, 29 August 2012 (UTC)[reply]

Tammy, I am not exactly sure of what you are implying by your statement. IP 165, I am not quite sure I get your point either. I take the term physical universe to mean the realization that all existence exists in relation to bodies, and the theory that bodies are comprised of particles. That is fine. But neither music nor shadows are bodies or are comprised of atoms, although they do supervene on the atomic. See supervenience and this article on supervenience at the Stanford Encyclopedia of Philosophy. Consciousness may be highly mysterious, but it is no more unreal or supernatural than are music or shadows, which are also relational existents, not entities. μηδείς (talk) 01:49, 30 August 2012 (UTC)[reply]

Physicists can explain music and shadows with physics, duh. Did you not read my comment? MMM, yes, I propose that there are, uh, invisible only partially detectible dimensions that only partially interact with our world, yes, entire universes in fact! that's the ticket! I would say that sounds alot like a description of consciousness.165.212.189.187 (talk) 12:48, 30 August 2012 (UTC)[reply]

What aspect of consciousness does that sound a lot like ? Sean.hoyland - talk 12:55, 30 August 2012 (UTC)[reply]

Just off the top of my head: Through our bodies our consciousness, which can contain a vast amount of information, is able to interact with the physical world (only partially) but we could never manifest a "consciousness" into a physical tangible thing. We each have a consciousness = multiple universes. "There is something else "out there" but we cant explain it."165.212.189.187 (talk) 12:59, 30 August 2012 (UTC)[reply]

Excerpt from a scientists journal: I was studying these atoms in my microscope and all of a sudden they began to thrash about in unison and with what musicians call a "rhythm". THis is unexplainable. what is causing them to do this? Answer: THe person whose body contained those atoms was dancing to "Call me maybe". So it must be Carly rae Jepsen!165.212.189.187 (talk) 14:27, 30 August 2012 (UTC)[reply]

If by manifesting into a physical tangible thing, IP 165 means appear as a body, neither music nor shadows do that. If he means be observable, we are aware of our own consciousness and the consciousness of others, and can measure it with electro-encephalograms and other imaging equipment. Nor am I aware of any phenomena like vision that has been studied by scientists that needs positing ghosts from the aethereal plane (nowadays they call it the multiverse) to cover some part "physicists" can't "expalin with physics". I am not sure any point more coherent than "duh" can be extracted from what was said. μηδείς (talk) 17:58, 30 August 2012 (UTC)[reply]

That was the most important point anyway. Can you explain the origin of consciousness with physics? Please address my post of 12:59, as it relates to occams razor.165.212.189.187 (talk) 18:19, 30 August 2012 (UTC)[reply]

You don't seem to have understood a word I have said so far. You cannot have a coherent theory of consciousness without an understanding of metaphysics, and the realization that not everything is itself a body. Consciousness is not a thing separate from the thing which is one's body. Just like weight is real but not a thing, and just like weight exists as a relationship between a body and the earth, consciousness is a relationship between a certain type of living being and its environment. Consciousness no more works "through our bodies" than do shadows or weight. It is not something separate or detachable from the body, and certainly has no agency separate from the body. There is no more consciousness before, outside, and separate from the body than there is a shadow which exists before, outside and separate from the body. To demand an explanation of consciousness (an emergent biological phenomenon) on the level of physics--i.e., in terms of mass and velocity--is a profound category mistake. μηδείς (talk) 05:56, 31 August 2012 (UTC)[reply]

Weight and shadows do not actively consume energy like a consciousness does. So then all human consciousness is no different than a sunflower moving with the sun, or in other words no more than instinct?165.212.189.187 (talk) 14:11, 31 August 2012 (UTC)[reply]

Consciousness is not something over and above brain activity. Any energy expended is expended by the brain metabolism, not by some weird force called consciousness over and above the brain activity. The notion of consciousness as a thing separable from the body goes back to the ancient notion that your life is your breath (the word anima literally means "breath") consisting of a cloud of air that can escape the body when you die. There is no spirit molecule or spirit energy above or separable from the body.

Consider poison. Poisonous substances are not poisonous because they have, in addition to, say, carbon and nitrogen atoms, a certain number of Poisonium atoms in their molecular formula, or because they vibrate at a toxic frequency, or because they emit poisonous Phoitons. The molecule itself is poisonous due to its nature in a certain context, even though the individual atoms that make it up aren't poisonous and it doesn't have any "poison energy". The same with consciousness. There is no Conscionium atom, or Sodium Conscionol molecule, or even Master Consciousness Neuron. See homunculus argument and representationalism. There is just the innervated creature itself, one of whose attributes due to its nature in a certain context is that it is conscious.

Rather than an instinct, consciousness appears to be a harmonic relationship that exists due to the complex rhythmic firing of neurons, a sort of music of the brain induced in it by the environment similar to the way one vibrating tuning fork will induce vibration in another. That's a scientific theory, not something a philosopher is entitled to claim is true a priori. But the relational nature of entrainment (see Entrainment (physics), Entrainment (biomusicology), Brainwave entrainment) is compatible with the relational nature of consciousness. μηδείς (talk) 17:11, 31 August 2012 (UTC)[reply]

If a body reverses direction, does it momentarily stop?

If I throw a ball up into the air, at the apex of its flight before beginning its descent, is the ball motionless or is it constantly either moving up or down? Ankh.Morpork 18:38, 28 August 2012 (UTC)[reply]

If a ball is thrown straight up and follows the same path down as it does up, its instantaneous velocity will be zero at the apex. If the ball has any kind of arc, the horizontal component of the velocity will remain constant (subject to slight slowing due to air resistance, usually ignored for spherical cows) while the verical component of the velocity will be zero for an instant. Note that this is a literal instant, there is no measurement of time small enough over which the ball is not in some sort of absolute motion. However, when you reduce the time scale between measurements to zero, there will be a time, right at the apex, where the instantaneous velocity is actually zero. This takes some calculus to understand better, but if you know calculus, what that means mathematically is that the first derivative of the vertical position function of the balls path will be zero at the point in the path where the ball starts its decent. --Jayron32 18:44, 28 August 2012 (UTC)[reply]

Can you help me understand why when a fly flies horizontally into an oncoming car and then travels in the opposite direction squashed on the windscreen, there can be a period while the fly is motionless, since as soon as it makes contact, it would begin to move in the opposite direction ? Ankh.Morpork 19:09, 28 August 2012 (UTC)[reply]

Certainly. If you picture the fly's velocity towards the windshield and express it as simple scalar quantity, say we define the motion of the fly as positive numbers, therefore any motion in the opposite direction could be expressed as negative numbers. So, lets say the fly is going at +1 meter/second and a car is coming along at a speed (defined by our convention) at -10 meters/second. The fly would then have to change its velocity from +1 meters/second to -10 meters/second. You can't travel between the number +1 to -10 without passing through the number 0, so at some point the fly's velocity will be actually zero. This, remember, is a measure of instantaneous velocity and not average velocity. There is no period of time when the fly is not moving (that is, if we actually watch the fly, there is no two times, t₁ and t₂ between which the fly is not in motion. However, there will be a specific instant of time, in the limit where t₂-t₁ = 0 (that is, where no time passes) that the fly will have an instantaneous velocity of zero. This is a lot easier to understand with some rudimentary calculus under your belt, but even without it, I think my example above of the fly needing to get from a speed of +1 meters/second to -10 meters/second should work. Does it? --Jayron32 19:32, 28 August 2012 (UTC)[reply]

Thank you for your explanation. Can you reconcile "at some point the fly's velocity will be actually zero." with "there is no period of time when the fly is not moving" as not being mathematically adept, I don't quite understand this important distinction. The cross-over from a positive to a negative velocity must surely occur at a specific point in time, and if the fly is in constant motion, how do these two facts correlate? Ankh.Morpork 19:55, 28 August 2012 (UTC)[reply]

Sure. Picture a movie about the fly's motion which is say, one second long. At no point in that film will the fly not be moving. Now, picture a movie that is 0.1 seconds long. At no point in that movie will the fly not be moving. Now, picture a movie that is 0.000001 seconds long. At no point will the fly not be moving. Do you see what I am doing? I'm making the time span when I start and stop the movie recorder smaller and smaller. As long as there is an actual movie, there will be actual motion. Now, what calculus allows us to do is to consider the situation of the 0 second movie. Not 0.1. Not 0.0000001. Not even 0.0000000000000000001 second movie, but an actual 0 time movie. See, even in a 0 time movie, the fly is still in motion, we've just stopped the film at an instant. It is a bit like pausing the film and asking "At what speed is the fly moving in this still frame" For nearly all points in time, the fly will have a non-zero velocity. However, in the transition when he changes direction from forwards to backwards, on a single frame of that film, his velocity will actually be zero. This is an idealized film, however, where each frame is an infinitely small moment of time after the next (not a real film, where each frame has a gap when it isn't recording anything). In calculus, we call this the instantaneous rate of change and it is the rate of change of a function where the domain over which you are measuring the function is reduced to a single point. Does that work? If not, I have more analogies and examples. --Jayron32 20:06, 28 August 2012 (UTC)[reply]

OK I understand (I think) that for any period of time there will be motion, but yet for a specific time frame - the O time, the frozen film - the fly is capable of having a velocity of zero. I confess I still can't wrap my head around this concept so will bother you with some inane questions.

Doesn't this this 0 time occur within a period of constant motion? On a velocity-time graph, doesn't the line intersect the time axis at a specific point while the fly is in motion?
Why doesn't the fly have zero velocity in the transition of forwards to more forwards because so too, at every specific time frame, the fly is motionless. You can pause a movie whenever you want to and when you do all the frames are still - sorry if I'm taking the analogy to literally. Ankh.Morpork 20:33, 28 August 2012 (UTC)[reply]
- Think of plotting a fly's velocity on a number line and watching a video of the dot travel along the number line as the fly's velocity changes. When the fly changes from moving forward to moving backwards (or the opposite), and only at that time will the dot cross the "zero" point on its trips up and down the number line. If the fly were traveling forward at 5 m/s and then was slowed constantly to 3 m/s or sped up to 8 m/s, it never actually crosses the zero velocity point. It is only when the sign of the velocity changes that you cross zero, so it is only in events that cause the sign to change (i.e. from forward to backward) that make the instantaneous velocity of the fly zero at any one point. Also, you misread the explanation a bit. In any specific "frame" of the film, the fly does have a velocity. It is only in the one singlular frame that captures the exact instant when he's transitioning from forwards to backwards when his instantaneous velocity is actually zero. --Jayron32 21:59, 28 August 2012 (UTC)[reply]

Maybe if its an incompressible spherical fly. lol. Isn't there a time when the front half of the fly is going backward while the back half is still going forward?165.212.189.187 (talk) 19:46, 28 August 2012 (UTC)[reply]

bsolutely. That's why they say that the last thing to go through a fly's mind when it hits a windshield is its ass.--Shantavira|^{feed me} 20:17, 28 August 2012 (UTC)[reply]

This seems like a very basic question. The trajectory of the ball when it comes back down is exactly the same as if you'd released it from a stationary position at the exact moment when it reached the highest point. So yes, the ball stops after it goes up, and it falls exactly like a stopped ball would. Wnt (talk) 14:20, 29 August 2012 (UTC) (ignoring, I suppose, the tiny whoosh of air that comes up at it from the place it passed through on the way up)[reply]

The sun seemingly stops and reverses direction twice a year, relative to the celestial equator. That's why the term "solstice" is used: "sun stands still". ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:50, 30 August 2012 (UTC)[reply]

Historical alternatives to Darwinism (AKA Darwinian evolution)?

This question lies between history and science.

So far, I can only think of Larmarckism and Saltationism. How do they become unsupportable? What information supports Darwinism and fails to support the other two theories of evolution? What is the difference between acclimitization of an individual to the environment and Larmarckism? Do people fail to support Saltationism because changes in populations can only occur one step at a time and not all together (i.e. organ systems can not just pop out of nowhere but must build on something as a template)? Any other alternatives or is that all? Does Biblical creation suggest that all living creatures on earth just pop out of nowhere? Wouldn't the central idea of Biblical creation be closer to the meat experiment in which bugs would grow in the open jar but not the closed jar because creatures would only reproduce after their own kind and not just pop out of nowhere? If that is the case, then didn't that scientist failed to support Biblical creation (sorry, I can't say "reject"; I say "support" or "fail to support"; I could have also used "fail to reject" and "reject"; I do not say "accept" or "reject" because those terms are not equal), which suggested that creatures would just pop out of nowhere under given nutritious conditions instead reproducing after their own kind? 21:05, 28 August 2012 (UTC) — Preceding unsigned comment added by 140.254.226.201 (talk)

I count seven questions there. If you ask seven questions at once on a Ref desk, all you get is disorganized chaos. Could you try to distill this down to one or two questions that matter most, and then ask the others later? Looie496 (talk) 21:36, 28 August 2012 (UTC)[reply]

Some historical alternatives to Darwinian evolution in roughly chronological order:

Creationism
Lamarckism
(Darwin qua Darwin goes here)
Theistic evolution
Saltationism
Mutationism
Biometric evolutionism (Karl Pearson, Walter Frank Raphael Weldon, to some degree Sir Francis Galton)
Modern evolutionary synthesis (not strictly identical with Darwin qua Darwin)
Punctuated equilibrium (which is not strictly Darwinian)
Intelligent Design

As for what leads to one or another, there are the short (somewhat wrong) answers (e.g. "Lamarckism was disproved by August Weissman when he observed that cutting off the tails of mice did not produce mice with shorter tails" — even Weissman knew that under orthodox Lamarckism this would not produce a result) and longer (somewhat dull) answers (like Peter J. Bowler's long but somewhat dry book, Evolution: The History of an Idea). The short version is, when you correlate all of the different types of data — observational, fossilized, genetic — the modern evolutionary synthesis (neo-Darwinism, or Darwinian evolution plus modern population genetics) still comes out on top.

There are many forms of Creationism; some are quite magical ("God woke up one day and said, let's have some giraffes"), some are more naturalistic (e.g. theistic evolution or intelligent design, in which God is either driving evolution or just occasionally intervening when things get hard). In the case of things popping out of nowhere, the actual popping in and out of existence is assumed to be miraculous and not subject to experimentation. --Mr.98 (talk) 22:14, 28 August 2012 (UTC)[reply]

Lamarckism fails for two reasons. There is no experimental confirmation. (I don't remember what experiments were actually tried, but, for example, cutting the tails of mice would not, after any long number of generations, result in a trend toward shortening tails.) Second, there is no mechanism to encode a physical change back into the genome. Causality goes in one direction only, genes > proteins > development > form and not the other way around. This question does seem like a homework question. μηδείς (talk) 01:20, 29 August 2012 (UTC)[reply]

Classical Lamarckism required a "vital force" within the animal — it doesn't happen from just external forces, but was the result of "striving" by the animal itself. So the cutting off of the tail experiment was something of a canard. That doesn't make it correct, of course. Similarly, there are some cases that the central dogma doesn't cover, e.g. epigenetics. --Mr.98 (talk) 02:25, 29 August 2012 (UTC)[reply]

But was the mouse experiment itself ever done? I know that experiments were done. As for striving, I never heard that dark or light skin was caused by striving, just due to tanning or the lack of. μηδείς (talk) 02:55, 29 August 2012 (UTC)[reply]

Weissman did cut off mouse tails, yes (68 mice, then all of the tails of their children for five generations). But such a thing would not have convinced a hardened Lamarckian. Again, Lamarck qua Lamarck has vital forces as the main mover. It's incredibly vague in many ways, and it's not super surprising that even Darwin himself was somewhat Lamarckian in his own hereditary proposals. The lambasting of Lamarck in the mid-20th century — which is the source of all of the current biology textbooks — is as much meant as a covert lambasting of Lysenkoism as anything else. There is a funny Cold War dynamic to biological heredity which not a lot of people know about; it's one of the reasons the people who worked on extranuclear inheritance were treated like pariahs for a long time. There is a terribly dull book on this that I'd be happy to recommend if anyone is interested... --Mr.98 (talk) 12:43, 29 August 2012 (UTC)[reply]

Actually there is a physical mechanism: proteins -> gene activation/repression -> histone methylation/acetylation/etc. -> DNA methylation -> CpG transition mutations. But you'd still need some circulating hormone to transfer a specific signal to the gonads. A higher level of growth hormone, triggered by environmental circumstances favoring larger animals in one generation, leading to mutations in genes affecting physical size - maybe. I don't know of any proof of such things, but I'm suspicious (for example, successful species tend to get larger, and humans have inexplicably gotten taller lately -though that could more likely be epigenetic based on the two preceding steps) But a signal to say "OMG my tail's been chopped off"? Probably not. Though you never really know until you try... Wnt (talk) 03:02, 29 August 2012 (UTC)[reply]

That's extremely technical, of doubtful use to a layman, and still doesn't amount to actual change in gene sequence caused by reverse design--just a rather random from the viewpoint of the phenotype environmentally induced change in gene expression.

Here's a paper on cutting off Daphnia antennae from 1931: A LAMARCKIAN EXPERIMENT INVOLVING A HUNDRED GENERATIONS WITH NEGATIVE RESULTS μηδείς (talk) 03:11, 29 August 2012 (UTC)[reply]

In case anyone isn't aware, I'll mention that Lamarckianism, in the form of "inheritance of acquired characteristics", has indeed been verified in some lineages. Though not available to charismatic macrofauna, Horizontal_gene_transfer_in_evolution is an important non-Darwinian feature of evolution that is broadly accepted in modern science. SemanticMantis (talk) 04:16, 29 August 2012 (UTC)[reply]

Good catch. Though aphids are sort of charismatic... and prone to more than one kind of more-or-less Lamarckism... and the things they do with their carotene... ! [4] Wnt (talk) 20:37, 29 August 2012 (UTC)[reply]

Horizontal gene transfer is not non-Darwinian, it's non-Mendelian. And it doesn't result from an acquired adaptation of the adult to its environment (like a stretched neck) being coded back into a change in the gene sequence coding for that preadaptation. μηδείς (talk) 01:36, 30 August 2012 (UTC)[reply]

Well, the aphids host organisms, then acquire some of their genes. That seems close to that. Of course, arguing over what a centuries-old notion would mean in terms of modern evidence is sort of quixotic. Wnt (talk) 15:03, 30 August 2012 (UTC)[reply]

But horizontal transfer like this lies somewhere between viral infection and freaky sex in its mechanism, and the result is purely darwinian, a "random" recombination of genes leading to an undesigned change that may or may not be successful. It has nothing to do with the organism acquiring some characteristic from its environment and causing a directional change in its genome. Its basically sensationalism and publicity seeking at best, and just plainsloppy thinking at worst, for scientists to say this sort of thing. The "logic" goes: Lamarckism is a weird theory of evolution. This is a weird evolutionary phenomenon. Hence this phenomenon is (kinda like) Lamarckism. That's the same sort of logic you get from the press: Space aliens and are weird creatures. This decaying raccoon corpse is weird. Hence this corpse is a space alien. See sympathetic magic. Scientists shouldn't engage in that sort of "thinking". μηδείς (talk) 17:14, 30 August 2012 (UTC)[reply]

Horizontal gene transfer has everything to do with an organism acquiring a characteristic from the environment, and then passing it on to offspring. Simply put, an offspring can have traits that the parent was not born with. You are right to say that it is non-Mendelian, and that is a sharper point. And it this phenomenon is not at odds with simple natural selection per se, as you describe, it fits in nicely. But HGT is most certainly not a phenomenon addressed by classical Darwinian theory. It is one of the reasons why we use terms like "modern evolutionary synthesis". Unless you are writing a research paper in evolutionary dynamics, it is perfectly acceptable to say that HGT is a mechanism that can allow for inheritance of acquired characteristics. SemanticMantis (talk) 17:09, 31 August 2012 (UTC)[reply]

No. one's parents are "in the environment". But getting their genetic characteristics by Mendelian inheritance is simply not Lamarckism. Acquired characteristics are characteristics one gets not from sex or transfer of genes but from environmental influence. Your claim is simple nonsense I won't debate with. μηδείς (talk) 22:07, 31 August 2012 (UTC)[reply]

August 29

Kepler-47

The caption on image 6 of this image gallery about Kepler-47 reads: "This screenshot from a NASA animation shows the orbital paths taken by the two known planets in the Kepler-47 system, which both orbit the same two stars." That last part seems intriguing to me. Do we know of an example where two planets in the same system orbit different stars? Dismas|^(talk) 00:26, 29 August 2012 (UTC)[reply]

My understanding was that the separate orbiting of one star in a binary system was the norm, and this "tatooine" situation was notable because it was the first confirmed where a planet orbited both binaries. μηδείς (talk) 02:59, 29 August 2012 (UTC)[reply]

The binary stars HD 20781 and HD 20782 have 2 and 1 confirmed exoplanets respectively. The binary stars HD 11964 and HD 11977 have 2 and 1 confirmed exoplanets respectively. Since these are wide-binaries, astronomers classified them as separate systems, so technically the answer to your question would be no.

In case a similar question comes up again in the reference desk, I found the answer by going to List_of_exoplanetary_host_stars, sort the table by the number of confirmed planets, and then shift-cliking every yellow row. Then I just do a ctrl-f for "binary" in each new tab.A8875 (talk) 03:54, 29 August 2012 (UTC)[reply]

Superheating and nucleation

From the superheating article: "Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid. ... Water is said to "boil" when bubbles of water vapor grow without bound, bursting at the surface. For a vapor bubble to expand, the temperature must be high enough that the vapor pressure exceeds the ambient pressure – the atmospheric pressure, primarily. Below that temperature, a water vapor bubble will shrink and vanish. Superheating is an exception to this simple rule: a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is an additional force, the surface tension, which suppresses the growth of bubbles."

I have three questions: 1) what are the usual nucleation sites in a "regular" pot of water that cause it to boil at 100C? Irregularities in the surface of the pot which trap pockets of air are one. Are there any others? 2) how do these nucleation sites actually promote bubble-making. (I don't see how trapping air will make it easier to form bubbles). 3) why do these bubbles only need to overcome the ambient pressure, and not the ambient pressure + pressure due to surface tension?

Thanks. 65.92.7.148 (talk) 00:57, 29 August 2012 (UTC)[reply]

Also, in bubble chambers, why doesn't the sudden formation of bubbles cause the whole thing to boil? 65.92.7.148 (talk) 01:01, 29 August 2012 (UTC)[reply]

Metal pots likely have LOTS of good nucleation sites, metals have a crystal structure and at the microscopic level are rarely very smooth, regardless of how they feel. It is almost impossible to superheat a liquid in a metal container for this reason. Amorphous solids like glass, that lack a crystal structure, make better containers to superheat a liquid in because they are truly smooth, and so lack nucleation sites. How nucleation sites work is explained in some detail at Nucleation, but the (over)simplified version is that nucleation sites provide a place for bubbles to collect roughly the same way that surface catalysts do: they provide a mechanism which lowers the activation energy necessary to make the transition from the liquid to the gas phase. In super simple terms: they give bubbles something to cling to while they form. Once a tiny bubble forms, it creates a surface; smaller bubbles have a greater surface tension per unit volume than larger ones do (that's because surface area grows as a square function but volume as a cubic function, so as the volume goes up by a factor of 1000, the surface area only goes up by a factor of 100, and the gap between the two gets bigger as the size continues to increase). That means the greatest surface tension exists for the smallest possible bubbles, and their just isn't enough gas inside these bubbles to exert enough pressure against the surrounding liquid to overcome their own surface tension, so they collapse on themselves and never grow. Nucleation sites basically break up the surface tension of these nacent bubbles, giving them the opportunity to form a stable bubble and float to the surface. --Jayron32 03:02, 29 August 2012 (UTC)[reply]

Thanks. In bubble chambers, ions apparently act as nucleation sites. Any idea how that happens?

Also, I'm looking for a text to brush up on the physics of phase transitions. I realized I have (pretty much) no idea what's "going on" when, for example, water starts to boil. Any recommendations? 65.92.7.148 (talk) 00:17, 30 August 2012 (UTC)[reply]

See symmetry breaking. Any sort of balanced high-energy system will collapse given the slightest chance to do so. You don't need to shake a balanced pin very hard to get it to fall over. μηδείς (talk) 01:30, 30 August 2012 (UTC)[reply]

Mars Science Laboratory Flight Path

Hi, I'm looking for the Curiosity Rover's flight path, something similar to this:

I checked the Mars Science Laboratory article and some of the related articles (like the timeline), but I can't seem to find it. Basically, I want to see the placement of the Earth & Mars during the takeoff & landing, and view the orbit of the planets while also keeping track of Curiosity's position, all of this relative to the Sun.

A snapshot of the celestial bodies' positions at takeoff, and a separate snapshot of the celestial bodies' at landing, would be helpful, but what I'm looking for is either an animation, or month by month snapshots at least.

Any help is appreciated, thanks!--99.179.20.157 (talk) 03:48, 29 August 2012 (UTC)[reply]

You can quickly estimate this via any Hohmann transfer orbit image, such as the one here. Most of them (like this one) are going to show you Earth position at launch and Mars position at landing, but it's pretty easy to extrapolate the rest. A ~230 day flight means that Earth has moved approx 2/3rds around its orbit by the point of landing, and that Mars needs to be backed up approx 1/3rd around its orbit to show the correct position at launch time. The speeds of both planets and the spacecraft can be reasonably approximated as constant. — Lomn 04:26, 29 August 2012 (UTC)[reply]

One way to watch the flight is JPL's Eyes on the Solar System (Java in browser required). Enter the launch date in Date+Time and use Speed+Rate to fly forward and backward in time. Click the spacecraft's name to center on it, and use the mouse to rotate the view, and just play with the controls. You can also see a quick demo at TED.

There are other planet position simulators, search the web, e.g. [5] - won't show the spacecraft but you can move in time from launch date to landing to see how the planets moved. 88.112.47.131 (talk) 11:46, 29 August 2012 (UTC)[reply]

professions

I've been reading these helpdesk answers for years and there are such brilliant replies. Which of the 'regulars' here actually work as scientists or as teachers/professors? I'm not looking for stats but just some short replies from the regulars. Thanks. Sandman30s (talk) 06:57, 29 August 2012 (UTC)[reply]

I used to be a freelance lecturer in colleges and universities in the UK. Now retired through ill health. --TammyMoet (talk) 08:11, 29 August 2012 (UTC)[reply]

Rocket scientist. --Stone (talk) 08:18, 29 August 2012 (UTC)[reply]

You left out an important class of knowledgeable people - Engineers. I started my career in Electronic Engineering, then when Govt policy killed off the Electronics industry in Australia, I worked in IT as a software Engineer & project manager, then became a diesel power generation Engineer. I have multiple diploma and degree level qualifications. Now semi-retired as in Australia if you are over 65 you can't be covered by accident insurance at work. I still do some consulting, and I'm also doing research. Ratbone121.215.24.39 (talk) 10:12, 29 August 2012 (UTC)[reply]

It wasn't intentional... also if you throw in engineers then there are many other classes who would regard themselves just as knowledgeable :) I was more interested in the academic/educational professions. Engineers are more than just academic... Sandman30s (talk) 11:31, 29 August 2012 (UTC)[reply]

I currently work as a scientist, and have also worked as a university lecturer. SemanticMantis (talk) 12:43, 29 August 2012 (UTC)[reply]

I'm a library technician, but I can't provide any published references to prove it. Mingmingla (talk) 20:21, 29 August 2012 (UTC)[reply]

I'm a chemistry teacher by training and exprience, but I am currently (voluntarily) not doing that. I am mostly a stay-at-home parent, and will be until my youngest child is in school. I do work some as a private tutor to keep active. --Jayron32 20:29, 29 August 2012 (UTC)[reply]

I have found that identifying yourself honestly at wikipedia (check my name at wiktionary) leads to being stalked and persecuted by rather disgusting partisan creeps, so I haven't chosen to come anywhere near my post www identity. Suffice it to say I am a credentialed professional with teaching and commercial experience and a love thereof. μηδείς (talk) 05:32, 30 August 2012 (UTC)[reply]

I own an aluminum baseball bat. --Jayron32 05:41, 30 August 2012 (UTC)[reply]

Do you discuss certain...nontraditional uses...of that on usenet? Or are you mentioning it here in terms of defense rather than previous online identities? DMacks (talk) 13:50, 30 August 2012 (UTC)[reply]

I'm a geological consultant and former university researcher (I'm more of a semi-regular here). Mikenorton (talk) 18:12, 30 August 2012 (UTC)[reply]

I've taught CAD. StuRat (talk) 03:25, 31 August 2012 (UTC)[reply]

General anaesthesia

Normally when general anaesthesia is administered to a patient, there is a lot of preparation before hand such as assessments, emptying bowels, ensurin the patient doesn't eat or drink before hand etc but how is all this done in emergency surgery in life threatening cases where patients are taken straight to surgery from emergency. Also are relaxants etc used before general anaesthesia to relax patients? Clover345 (talk) 10:56, 29 August 2012 (UTC)[reply]

Obviously they make do with what they can do. Emptying the stomach, for example, is to keep the patient from involuntarily vomiting and perhaps choking during the procedure. If you can get them to not eat anything before the procedure, it's one less thing for the anesthesiologist et al. to worry about. If you can't, it's one more thing for them to worry about. You don't let the perfect be the enemy of the good when dealing with emergencies. I've no clue about relaxants used before general anesthesia, but I have experienced cases of relaxants being used before local anesthesia, for whatever that is worth. --Mr.98 (talk) 12:36, 29 August 2012 (UTC)[reply]

It's common practice to administer a tranquilizer before general anesthesia -- see General anesthesia#Premedication. Looie496 (talk) 17:57, 29 August 2012 (UTC)[reply]

It is a question of relative risks. I have been anesthetized and sedated twice upon emergency room admission. The diagnosis was severe enough and the need to treat me so obvious that waiting for me to fast was not an option. That is for elective surgery. μηδείς (talk) 05:38, 30 August 2012 (UTC)[reply]

Carl Linnaeus Belived In The Fixity Of Species By Divine Creation And Died 31 Years Before Darwin Was Born. Why Then Does The Taxonomic System That Bears His Name Support Darwin's Theory Of Common

Carl Linnaeus Belived In The Fixity Of Species By Divine Creation And Died 31 Years Before Darwin Was Born. Why Then Does The Taxonomic System That Bears His Name Support Darwin's Theory Of Common — Preceding unsigned comment added by PAOH200 (talk • contribs) 13:47, 29 August 2012 (UTC)[reply]

Linnaean taxonomy is used in broadly to describe modern taxonomy in general, but in specific many aspects were dropped. For example, we no longer use Linnaean taxonomy for minerals. The basic observation made by Linnaeus is that species show a branching pattern of relationships, which is generally true in the case of plants and animals (but not absolutely so - see horizontal gene transfer). One way to account for this is that God willed it so, and indeed, the theory of evolution does not dispute that. What evolution does do is suggest a way in which it could have happened, which has since been borne out by a great number of experiments.

To make an analogy, when you find a brick lying in your living room, you might initially hypothesize that your son carried it in while he was playing. But when you find broken glass on the floor and a hole in your window, the brick is now evidence that someone threw a brick through your window. It is one of a set of observations that can be accounted for by a specific theory. Whether your son threw it in while he was playing ... bears further investigation. Wnt (talk) 14:07, 29 August 2012 (UTC)[reply]

Linnaeus didn't make that observation; he proposed an easy-to-use system of categorizing flora, fauna, and minerals so that naturalists in disparate parts of the world could sensibly known whether they were talking about the same critters or not, independent of whatever they were called in the local dialect. There is a fundamental issue regarding Linnaean taxonomy and Darwinian evolution, namely the species problem. But the trick there is that later, post-Darwin biologists have redefined their understanding of taxonomy into something quite different from Linnaeus (e.g. cladistics). The work of taxonomy today is somewhat related to Linnaeus, but the interpretation of what the taxonomy means varies starkly from those who see it as a series of fixed species, obviously. --Mr.98 (talk) 15:14, 29 August 2012 (UTC)[reply]

Darwinism is true, and the Linnean system is coherent with the facts. It doesn't intentionally support as in "argue for" Darwinism.. rather, the truth coheres. μηδείς (talk) 01:27, 30 August 2012 (UTC)[reply]

To take a simple analogy, Mendeleev produced the first Periodic Table of the Elements significantly before the development of atomic theory in its modern form, and yet the periodicity of the elements provides a good approximate understanding of the effects of subatomic structure on the physical and chemical properties of the element. In both cases, the classification system was not developed to promote the theory; the classification and the theory both describe the same scientific domain, and so used properly, they support each other. AlexTiefling (talk) 11:57, 30 August 2012 (UTC)[reply]

How audible would it be to a human?

These days, Charles Bolden and Will.i.am are amusing themselves by making their voices come out of a speaker on Curiosity on Mars. But Mars' atmosphere is very thin. I haven't been able to find out what the speaker's volume settings are, but if they are about strong enough such that on Earth, the volume would be 60 dB, about as loud as conversation in restaurant, office, background music, Air conditioning unit at 100 ft (source) at 3m distance from it, how loud in dB would it be about 3m away from Curiosity on the surface of Mars to a human who miraculously could survive without a helmet on? 20.137.18.53 (talk) 14:38, 29 August 2012 (UTC)[reply]

There is no speaker on Curiosity. The song and speech were transmitted back to Earth, not played on Mars. Bazza (talk) 15:35, 29 August 2012 (UTC)[reply]

Oh, after watching a video, I see that all that really happened was an audio recording was carried in a file on Curiosity, which beamed the electronic signal back to Earth. So we've been getting visual data from Mars since the 70s, but this is the first time we get audio from the surface. My POV, but that's kind of lame, and makes this headline seem misleading to me. 20.137.18.53 (talk) 15:42, 29 August 2012 (UTC)[reply]

If you watch the August 28 news conference, you'll see that at least two reporters were confused about what exactly this stunt was supposed to demonstrate. The answer was that this is the first rover with enough communication bandwidth to do this without interfering with more important data. Not exactly a significant milestone. --99.227.95.108 (talk) 20:09, 29 August 2012 (UTC)[reply]

Who gets paid for these sorts of publicity stunts? Wnt (talk) 20:44, 29 August 2012 (UTC)[reply]

It's still a viable question, though. All of a sudden the OP doesn't care to know?165.212.189.187 (talk) 15:12, 30 August 2012 (UTC)[reply]

Does 'Curiosity' have a microphone on board? if not, then why not?

Hi,

Does the Mars Rover 'Curiosity' have a microphone on board? If not why wasn't it planned for since I vaguely remember some scientists(Perhaps Carl Sagan) hoping to put a microphone on a Mars probe to hear the sounds of the Martian winds? — Preceding unsigned comment added by Gulielmus estavius (talk • contribs) 17:05, 29 August 2012 (UTC)[reply]

No. The scientific return is not high enough to justify the extra weight. [6]--Aspro (talk) 17:22, 29 August 2012 (UTC)[reply]

Aspro's link actually doesn't say why there wasn't a microphone, just that there wasn't. Plenty of people have pushed for including a microphone on a Mars mission, most notably the Planetary Society, whose microphone actually flew on the failed Mars Polar Lander. The Phoenix lander also included a microphone, but only because its descent imager (MARDI) happened to have a microphone on its circuit board. MARDI was turned off because it had a risk of interfering with IMU measurements during landing, which could have been fatal to the spacecraft. According to an interview I heard with a Planetary Society member (Emily Lakdawalla), the Society lobbied to have their microphone included on Curiosity, but it was rejected because the rover was already complex enough (she didn't elaborate on this, and I haven't been able to find a more detailed explanation). Personally I think that's a strange reason, because a microphone is one of the smallest and simplest electronic devices possible (just look at your cellphone to see how small it could be). Having one would be great for PR, and NASA only gets funding if the public is excited and inspired by its missions. --99.227.95.108 (talk) 22:26, 29 August 2012 (UTC)[reply]

You don't just need the microphone, though. You need a microprocessor, etc., to control it. The whole thing needs to be connected to the rover's power systems, and communication systems. Everything needs to be tested to make sure it doesn't interfere with anything else. Time needs to be scheduled to transmit instructions and results. Someone needs to control it. Someone needs to analyse the data. There is a lot involved with adding one seemingly very simple extra experiment to a probe. --Tango (talk) 22:36, 29 August 2012 (UTC)[reply]

I think we know what the sound of tires grinding along bare soil sounds like. I'm not sure there's a lot of scientific data to be gathered by putting a microphone on it. It's not like there are little green men who need a karaoke machine or something. --Jayron32 22:35, 29 August 2012 (UTC)[reply]

One reason might be that sound doesn't propagate well on Mars [7]: it's apparently a very quiet place. Not that you'd really expect to hear anything but wind and machine sounds from the rover anyway, but it would be easy from the LGMs to sneak up on you if you weren't paying attention: you'd never hear them coming (and their voices would be deepened by the carbon dioxide, sort of the opposite of the effect helium has). Acroterion (talk) 14:46, 30 August 2012 (UTC)[reply]

Certainly it would be worth hearing what Mars has to say, even if it is only the sound of its wind, of blowing grains of dust, the crunching of soil beneath the tires, maybe the occasional strange drummings of settling sand dunes. Sound carries a long way and it carries a lot of information. Maybe once in the mission it would even be something spectacular, a landslide on an old weathered slope that the surveyor can then locate from orbit.

The problem of the thin atmosphere and CO2 absorbing sound, of course, is serious, and it may be very difficult to get a sufficiently sensitive microphone to Mars. But apparently the CO2 absorbs mostly high-frequency sound, over 2000 Hz [asadl.org/jasa/resource/1/jasman/v10/i2/p89_s1], and absorption is affected by impurities like water vapor [8] (though I haven't read to see how). I wouldn't dismiss the idea so quickly - seeing another planet gives us a feeling for what it is, but hearing it gives us a sense of the spirit of the place. Wnt (talk) 15:00, 30 August 2012 (UTC)[reply]

InSight will have a seismometer so we may be able to hear what Mars has to say soon, at least in the seismic domain. Sean.hoyland - talk 16:08, 30 August 2012 (UTC)[reply]

I don't disagree: there are few places that we can get to that would provide an opportunity to listen to alien winds, and it would be extremely cool. Acroterion (talk) 17:54, 30 August 2012 (UTC)[reply]

Certainly it would have been cooler to hear some Martian winds than a rather ordinary Wil.I.Am single. Gulielmus estavius (talk) 18:03, 30 August 2012 (UTC)[reply]

I get the advantages of sexual reproduction, but what are the advantages of having separate sexes?

I read this article which suggests lesbians could create one day create sperm from their own bone marrow cells so they would be able to have children. However, I intuit that they would only be able to produce girls. If those girls were lesbians too, I could see a self-sustaining "Amazon" type of society, without the need for men. Which makes me think, why did mammals evolve separate sexes anyway? Couldn't you have meiosis without the need for separate sexes? After all, many plants have male and female gametophytes coming from the same plant/sporophyte. It seems to me you could have twice the reproductive capacity without the need for "dedicated" males.

I understand the selfish gene argument for why the sex ratios are 1:1, but that doesn't explain how the separate sexes got created. What was the evolutionary incentive for initiating separate-sex "sporophytes"? If selfish genes could create one parasitic class which cannot directly reproduce, why didn't they end up creating many? 71.207.151.227 (talk) 17:12, 29 August 2012 (UTC)[reply]

You are asking about evolution of mating types. That article is woefully stubby, but it does mention one use, which is regulation of reproduction. Many plants go to extremes to reduce the possibility of self-pollination, because having sex with oneself takes away many of the advantages of sexual reproduction in the first place. Some fungi take multiple mating types to the extreme, and have many thousands of sexes. Other plants are happy to self, but that's a different story. In fact, many different mating systems have developed, based upon the challenges that an organism faces, which depend on its life history, habitat, etc. Many species do exist mainly as hermaphrodites, such as many slugs. Note that separate mating types don't necessarily imply polymorphism (or sexual dimorphism). That starts with anisogamy, which arose long before mammals appeared. I'm not sure, but I think all ~~chordates~~ animals employ anisogomy, even in the case of hermaphrodtic slugs. The other case, isogamy (but still with different mating types) is apparently restricted to algae, fungi, and a few other groups. Finally, some unusual species are confined to one sex, such as the bdelloid rotifers. But that's not really true sexual reproduction, more of some weird derived intermediate state between sexual and asexual reproduction. SemanticMantis (talk) 18:45, 29 August 2012 (UTC)[reply]

As soon as there is some sort of heritable variability in sex cells, the "male" strategy of small and motile will become hugely successful compared to medium sized and immobile, since "sperm" will be much cheaper to produce in quantity and more likely to "score" than medium sized sex cells. Once sperm become ubiquitous, the rare egg will become a much more valuable commodity, and its increased size will increase viability, while its selectiveness among sperm (sexual selection) will increase the quality of offspring produced. First the male strategy is highly successful, and then presence of males makes the female strategy itself successful, leading two two stable "solutions" to the sex problem. μηδείς (talk) 01:24, 30 August 2012 (UTC)[reply]

Telomeric fusion and human evolution

It is well known that human chromosone 2 is just a fused version of primate chromosomes. But I have problems understanding how the new lineage that would eventually lead to modern humans actually propagated. If one individual had the chromosomal mutation, how could he even mate if the surrounding population had a different number of chromosomes? Or is it more likely that more than one individual had the same random chromosomal mutation? --Ghostexorcist (talk) 17:34, 29 August 2012 (UTC)[reply]

Having different chromosome numbers is not necessarily an impediment to reproducing. The various subspecies of horses have different chromosome numbers, and can still mate and produce fertile offspring. thx1138 (talk) 17:57, 29 August 2012 (UTC)[reply]

Can you give specific examples? I know mules are born sterile because they get an uneven number of chromosomes from their horse and donkey parents. A geneticist suggested several years ago that the lineages that eventually gave rise to modern humans and chimps might have continued to breed after their initial split and later split for a second and final time. Just like female mules can sometimes breed, the female hybrids could produce viable offspring. I don't think this has ever been proven, though. If the populations with different chromosomes could breed, I guess drift would play a part in making the fused chromosomes a dominant trait. --Ghostexorcist (talk) 18:15, 29 August 2012 (UTC)[reply]

Note that horse and donkey have some differences in the overall chromosome structure as well as the number - it's not as simple as the end-to-end fusion in humans.[9] Wnt (talk) 21:28, 29 August 2012 (UTC)[reply]

It basically comes down to a question of whether meiosis can still occur, or whether it gets blocked at some stage. Looie496 (talk) 18:37, 29 August 2012 (UTC)[reply]

Note there are genes at the fusion site of substantial interest. As for the genetics of it, the 1-2 would still be homologous to 1 and 2; the only question is whether sometimes the 1-2 gets pulled between opposite poles and torn apart (embryos which would be weeded at an early stage). I haven't figured that one out, but there's at least a 50-50 chance it wouldn't happen, simply by chance. Wnt (talk) 21:16, 29 August 2012 (UTC)[reply]

These explanations are helpful, but does anyone know of a particular book or paper that describes the process in full? --Ghostexorcist (talk) 22:34, 29 August 2012 (UTC)[reply]

I don't think it is really understood. As far as I can see, the most informative paper is this one, for what it's worth. Looie496 (talk) 23:15, 29 August 2012 (UTC)[reply]

Any acquired immunity to rubella when an infant gets it pre-vaccination?

According to Rubella, the first administration of the MMR vaccine usually occurs around 12-18 months, but I wonder if a baby experiences the virus before that vaccination, does the baby's immune system get any "education" on how to combat future exposures from that? I'm not talking about CRS or an extremely young newborn, and of course this is not to say that that would preclude vaccination (that's not even my question). I was just wondering the biological question of whether or not an as-yet non-vaccinated human gets any immunological benefit after having gone through it and survived it in the specific case of Rubella. 20.137.18.53 (talk) 20:29, 29 August 2012 (UTC)[reply]

Rubella being more commonly known in the UK as "German measles" when I was growing up, the received wisdom was that you could get it more than once. I myself had it three times before I was 20. Measles, however, you only got once, and I can remember going to measles parties so that I'd get it and be immune. Vaccinations for these diseases didn't exist when I was a little girl. (This was, of course, in the dark ages BC - Before Computers.) This is, of course, completely OR and unsourced and I'd appreciate it if someone could provide some proper references. --TammyMoet (talk) 20:35, 29 August 2012 (UTC)[reply]

It is sourced, we're just not "reliable". ;) 21:59, 29 August 2012 (UTC)

This appears to say that you only get rubella once.[10] Rmhermen (talk) 22:56, 29 August 2012 (UTC)[reply]

I always wondered what actually happened at measles parties; do you go around kissing each other? (The article doesn't say.)--Shantavira|^{feed me} 10:21, 30 August 2012 (UTC)[reply]

We basically sat and played games together as far as we could, and kissed bye-bye... --TammyMoet (talk) 14:02, 30 August 2012 (UTC)[reply]

August 30

Star positions in the past

Is there a website or a software that's capable of telling me where were certain stairs on the sky in a given year (e.g. in 1400)? 193.224.66.230 (talk) 13:11, 30 August 2012 (UTC)[reply]

This page will do it, but it's a bit tricky to navigate. Page down to the "virtual telescope" and select the "controls" link to set the date and time you wish to look at the sky for. The Earth's view of the stars has changed over time, but I think that a difference of 600 years isn't going to have changed it much; excepting the locations of the planets and comets and things like that. The star map would only look noticibly different on scales of 1000s of years or 10,000s of years. --Jayron32 13:18, 30 August 2012 (UTC)[reply]

Celestia. If you haven't used it before, and you're at all interested in space, you're missing out. I agree that 600 years isn't enough to see the stars move noticeably. To get a sense of how slowly they move, Barnard's star, the star with the highest proper motion, moves 3 degrees in 1000 years. Almost every other star moves many times slower than that. You can use Ptolemy's star charts today and they wouldn't seem wrong. --99.227.95.108 (talk) 15:40, 30 August 2012 (UTC)[reply]

As far as I can tell, Celestia doesn't model proper motion. TenOfAllTrades(talk) 21:23, 30 August 2012 (UTC)[reply]

I'd go with Stellarium as it's probably the easiest program to get the hang of. (There are download links on the article page.) But as said above, there wouldn't be a noticeable difference in the positions of stars over a 600 year period. FlowerpotmaN·(t) 19:04, 30 August 2012 (UTC)[reply]

Attractiveness

Is attractiveness subjective? From my understanding, attractiveness is based on certain dimensions an proportions of the face and body of a person. However is this subjective? And if so, are there certain faces, which people universally find attractive or unattractive? Clover345 (talk) 15:16, 30 August 2012 (UTC)[reply]

Physical attractiveness has both objective and subjective components. That is, there are some trends and nearly universal principles, but there are also many factors that are determined by individual taste, and will vary culturally or even person to person. --Jayron32 15:54, 30 August 2012 (UTC)[reply]

You may be interested in research on facial attractiveness [11]. You can also participate in real research at that site, making your preferences part of the process. Recently, many different studies have demonstrated that averaged faces are rated as more attractive than the average of many facial attractiveness ratings. This starts to get at "universally attractive" faces, but as Jayron points out, there will always be a large degree of subjectivity in attractiveness. Google /average face attractive/ for many news and pop-sci accounts. SemanticMantis (talk) 18:09, 30 August 2012 (UTC)[reply]

Star Gazing Hobby

I want to start this hobby but with the meager savings I have. I will like to purchase a used telescope on eBay however I don't know where to begin to look or what to look for. Please give me any suggestions on how to start my hobby the right way Reticuli88 (talk) 16:25, 30 August 2012 (UTC)[reply]

One option is to see if a local astronomy club exists. Near where I live, the Morehead Planetarium and astronomy department at the University of North Carolina sponsors a monthly stargazing night at Jordan Lake, far enough away from light sources but close enough to see some cool stuff. They bring some really powerful telescopes and set them up on the beach, and it doesn't cost anything to come by and use their telescopes. This google search turns up a wealth of other similar arangements. --Jayron32 16:49, 30 August 2012 (UTC)[reply]

I strongly second Jayron's suggestion. Speaking as someone who read Astronomy at University and helped to run a local Astronomy Club myself, I'd say it would be near-impossible for someone new to the activity to choose with confidence an appropriate instrument from eBay or similar sites. You may be able to track down a local club from the back pages of Sky and Telescope or a similar magazine. Alternatively, if you can get to a specialist Astronomical Telescope vendor, they're likely to give you reliable advice because they'll be hoping to get repeat business from you when, as is likely, you trade up to better/more expensive equipment. {The poster formerly known as 87.81.230.195} 84.21.143.150 (talk) 17:16, 30 August 2012 (UTC)[reply]

The beauty of astronomy is that it can be done purely with the eyes alone. Learn the patterns of the constellations: learn the planets, what they look like in the skies: try and see how many of the Seven Sisters you can see with the naked eye (northern hemisphere only). If you get a cheap pair of binoculars from Ebay second hand, you can see details in some of the globular clusters. Be warned, however: you will never see the range or depth of colours you see in the professionally produced deep sky photos. I have known some enthusiastic amateurs give up when they realise that. --TammyMoet (talk) 18:38, 30 August 2012 (UTC)[reply]

Other people have written much more about this exact subject than we possibly can. See, for example, this Sky&Telescope article. --99.227.95.108 (talk) 03:48, 31 August 2012 (UTC)[reply]

I can tell you from childhood experience that a small refracting telescope will probably be worth far less than you would pay for it. You might as well get a good pair of binoculars. A friend's father had a six inch reflecting telescope. Due to its mass it was much more stable, and you could see the disks of planets which were mere dots with my "telescope". μηδείς (talk) 05:28, 31 August 2012 (UTC)[reply]

Raptor factoid

Concerning fish-eating raptors, such as Ospreys and Sea eagles that hunt by swooping down and grabbing fish from the water with their talons... any truth to the oft-quoted fact(oid?) that because the bird is allegedly physically unable to unclench its feet whilst they're embedded in the prey's flesh and let go, unless it returns to dry land, that if the bird happens to 'attach' itself to a fish that's too large to carry, that it will probably either drown on the surface due to becoming waterlogged - still attached to a dead fish, or be dragged under by the fish as it tries to escape - and drown that way?

I'm aware that these birds can only swim a little and do sometimes drown after miscalculating/missing their prey, getting too wet to fly and being trapped on the water's surface but that would seem to be a different scenario. --Kurt Shaped Box (talk) 20:06, 30 August 2012 (UTC)[reply]

Why did people in the late 1800s think an aether was necessary for the propagation of light, when Maxwell's equations show that this is unnecessary?

Maxwell described light as an electromagnetic disturbance of self-propagating E and H fields. Surely people in the late 1800s knew that magnetic and electric fields could exist in vacuum. So why did they think an aether was necessary to "carry" light waves? 71.207.151.227 (talk) 20:11, 30 August 2012 (UTC)[reply]

It is not self-evident that electric and magnetic fields can exist in a vacuum, even if you have Maxwell's equations in front of you. This requires careful, meticulous understanding of the equations, and of course the equations require a lot of experimental effort to validate. Among the relevant work that helped establish this fact: the Michelson-Morley experiment, which you've undoubtedly read about; and the experiments that established Vacuum permittivity and Vacuum permeability constants. Maxwell's original work, A Dynamical Theory of the Electromagnetic Field, which you can read online, was a study of the relationships between electric fields and magnetic fields and charges. It is not immediately obvious, just from that work, that his work implies propagation of energy in a vacuum. The science developed; the theories became more perfect, and the experiments continued to validate assertions; and eventually the majority of scientifically-minded people accepted as fact that there need not be any transmission medium to hold the fields. We can say that Faraday and Coulomb discovered these facts; but that's almost irrelevant: at what point did the consequences of these facts become well-known? There's hardly a single instant when we can say "this was the moment that people understood that electromagnetic waves propagate in vacuum." Nimur (talk) 20:34, 30 August 2012 (UTC)[reply]

The fact that waves propagate in a vacuum feels intuitively wrong when you consider what a wave is: it is a rhythmic motion that propagates through something. When light displayed wave-like properties, people began to ask "what is it propagating in". The Maxwell equations don't require a medium, but people's expectations did. --Jayron32 21:32, 30 August 2012 (UTC)[reply]

"It is not self-evident that electric and magnetic fields can exist in a vacuum.." What decade of the 19th century were the experiments done, with vacuum pumps and bell jars, to prove that magnets worked just fine in vacuum, and that electric fields in a vacuum affected charged objects? I suppose one could cavil that the bell jar vacuum is imperfect compared to the vacuum of outer space. Faraday found magnetic effects in a Torricellian vacuum (like the inside of a mercury barometer above the mercury) (p 194) in his research published as a collection in 1855, but much of the research was done and published earlier. Didn't anyone experiment in the mid or early 1800's with electrified objects in a high vacuum jar to [rove the functioning of electric fields? The writings of Brewster suggest so, though he wrote mostly about discharge and glow effects in vacua. rather than basic attraction and repulsion experiments as done in air. They knew by the 1830's that a charged object would discharge and that charge could be transferred in a Torricelian vacuum. Anyone calling himself a physicist or "natural philosopher" by 1860 would likely have been familiar with this. Edison (talk) 00:40, 31 August 2012 (UTC)[reply]

Lots of people experimented with discharges and vacuums, but it was harder than you let on to get a good vacuum in the 19th century. If your vacuum was poor, you got very messy results — the gas inside the tube would ionize, for example, insulating the discharge stream, and give you completely the opposite conclusion. The fundamental work done that established that indeed, cathode rays were affected magnetically was done only in 1896, by J.J. Thomson, and was part of the discovery of the electron. The real breakthrough experimentally was creating an unambiguously good vacuum, something that evaded even the great German experimentalists like Hertz and Lenard. All of which to say is — the point at which it became unambiguous was really quite late into the game, just a few years prior to Einstein and all that. The limitations were for the large part technical. --Mr.98 (talk) 00:56, 31 August 2012 (UTC)[reply]

Because it was known that according to Maxwell's equations, EM waves travel at a specific, finite speed c. The question immediately asks itself: relative to what? Usually, if you have a speed, you must have some definition of a stationary point with v=0. Defining stationarity at every point in space gives you a sort of aether. Of course, we know now that the speed of light is invariant and comes out the same for all observers. However, this requires us to give up any notion of absolute time, stationarity, and a lot of other notions in order to formulate special relativity. It seemed far more parsimonious to keep Newtonian physics and to suppose that light travels through an aether, than to eliminate the aether and also throw out all the known laws of mechanics. Given what was known at the time, I think this was a reasonable application of Occam's razor. --Amble (talk) 00:47, 31 August 2012 (UTC)[reply]

Just a point: the constancy of c was not in fact known until the late 19th, early 20th century. This was part of the point of Michelson-Morley. --Mr.98 (talk) 00:56, 31 August 2012 (UTC)[reply]

The constancy of c (or

1/{\sqrt {\epsilon _{0}\mu _{0}}}

or however you want to write it) is a property of Maxwell's equations. To someone ignorant of later developments (such as Maxwell himself) the theory looked mathematically like a description of transverse sound waves in a solid, and it was natural to wonder about the properties of that solid, including its state of motion. -- BenRG (talk) 02:54, 31 August 2012 (UTC)[reply]

Maxwell himself used the idea of the aether as a way to think through how the world worked. It was a visual metaphor to use as a means of interrogating nature. (Maxwell's own visualizations of the aether are amazing — pulleys and gears and whatnot. See figure 2 here. Very industrial age U.K.) Maxwell derived all of his original equations from these sorts of models, and had tremendous success with them. (The version of Maxwell's equations you are now familiar with are not Maxwell's own; they were re-written by Heaviside and others some time later.) When you get success out of a model, you don't turn around and throw out the major components of it immediately afterwards.

For the physicists of the day, the aether was actually considered a brilliant theoretical innovation. It was more than just the medium through which light moved — it was the interface between the world of electromagnetism and the world of matter. The theorists of the day came up with beautiful, elegant, and totally physically sensible models about how all matter arose out of whorls and knots in the aether; how this sublime otherworldly realm of pure energy lent itself towards the manifestation of all that we are and can observe. They saw it not as an appendage onto Maxwell's equations, or as an extremity on to the physical universe, but as a supremely elegant concept that also made good intuitive sense (light is a wave in something, right? Who's heard of a wave in nothing?). Beautiful physics came out of it. The problem was, well, it didn't exist, it wasn't necessary, and in fact they were going about it all the wrong way. We know that now, and it's hard to put yourself in the head of someone then, but look at the aether as the original theory of everything, the one-stop theoretical shop for All of the Rest of Physics. --Mr.98 (talk) 01:08, 31 August 2012 (UTC)[reply]

Honestly, not much has changed. The modern quantum vacuum has a lot of structure, and any particle physicist will tell you that particles are oscillations of the vacuum, not objects in the vacuum. The vacuum is similar enough to a solid that many phenomena of fundamental quantum field theory appear also in solid-state physics. The vacuum undergoes phase transitions, like the Higgs field condensation that breaks electroweak symmetry. Mechanical analogies haven't died. Quantum Field Theory in a Nutshell by Anthony Zee introduces the field as a "mattress" of weights connected by springs. It seems unlikely that the world really is a mattress simply because Lorentz invariance unifies space with time, and it would be strange if at a deep level space and time are aspects of the same thing but at an even deeper level they're not. There are hints (from gravitational holography and AdS/CFT) of a radically different underlying structure for the world. But the best modern theories of fundamental physics (general relativity and the standard model) are still mattress-based. In fact the next thing Zee does after introducing the mattress analogy is complain about the lack of anything better. -- BenRG (talk) 02:54, 31 August 2012 (UTC)[reply]

would maxwells aether be able to penetrate a black hole or its event horizon?GeeBIGS (talk) 04:04, 31 August 2012 (UTC)[reply]

Read Luminiferous aether and it should clear up any questions. The problem with the idea was that it had to be infinitely dense and infinitely malleable, which kinda doesn't work. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:27, 31 August 2012 (UTC)[reply]

What are the differences between male and female human faces? In words...

This may be easy for lots of editors but not for me. Forgetting facial hair, which not all men have, how can we describe the general differences between men's and women's faces? Tom Haythornthwaite 22:41, 30 August 2012 (UTC) — Preceding unsigned comment added by Hayttom (talk • contribs)

Look at Eric Roberts and Julia Roberts and tell where you see differences - if any. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:49, 30 August 2012 (UTC)[reply]

Thank you, I think, but either you didn't understand my question or I didn't understand your answer or we have different senses of humour. It is easy to describe the general differences between male and female bodies because men are generally taller and have penises and women generally have breasts, and so on. But I cannot think of words to generally differentiate between their faces. hayttom 23:11, 30 August 2012 (UTC)[reply]

What I'm saying is that you can't, necessarily. To my mind, forgetting any facial hair, Eric and Julia look a lot alike. If you were to somehow remove all the hair anywhere on their heads and put their faces side by side, it would be hard to tell the difference. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:57, 30 August 2012 (UTC)[reply]

See this article on the role of testosterone in the development of male facial features. Alansplodge (talk) 23:34, 30 August 2012 (UTC)[reply]

My impression is that women are more likely to have the so-called "heart-shaped face", where the sides of the face slope inward as you go from the temples towards the mouth, whereas men are more likely to have straight-sided faces. Not sure I'm right; would be interested to hear about any real studies. --Trovatore (talk) 23:37, 30 August 2012 (UTC)[reply]

Leaving out individual variations, the basic difference is that female faces are more round, and male faces are more rectangular. Looie496 (talk) 00:07, 31 August 2012 (UTC)[reply]

That would be the reason rectangular, straight-side faced women, Ann Coulter for example, are sometimes referred to as "horsey" looking. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:11, 31 August 2012 (UTC)[reply]

Males tend to have more prominent brow ridges - the easiest way to tell from just a skull, as I learned in the palaeoanthropology lab at uni - though even that can be misleading sometimes. As for the heart-shaped vs straight-sided face, that is mostly due to males having more developed jaw musculature, I'd assume - and that will be rather variable. Combined, these two traits tend to make a male face look 'squarer', though I think that if you remove the cultural clues, it is often difficult to be sure just from the face. With children, it is even harder, and I suspect pre-puberty next to impossible from a casual inspection. AndyTheGrump (talk) 00:12, 31 August 2012 (UTC)[reply]

Just to add in, those are the two things they told us in my forensic anthropology as well. The square jaw is not from musculature; it is skeletal. Women on the whole have large jaw angles than men do. Again, as you note, none of these skeletal features — even the non-facial ones, like hip bone shape — are a sure-thing, because there's a lot of variation in the species. --Mr.98 (talk) 00:47, 31 August 2012 (UTC)[reply]

How would you characterize the jaw structure of this Savannah they have on the Today show now? There's something odd-looking about her - like a squirrel with its cheeks stuffed, or something. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:30, 31 August 2012 (UTC)[reply]

The Adam's apple is one differenece. Not 100% of the time, but on the balance, men tend to have a more prominent Adam's apple than females. --Jayron32 04:11, 31 August 2012 (UTC)[reply]

August 31

Is there a way to help someone run faster?

Suppose a man and woman are both running away from a scary monster, and the man wants to help the woman run faster. This is a common scene in movies, and in said movies, the man usually holds the woman's arm to drag her forward. I've tried this before, thankfully without the monster, and it's an extremely uncomfortable way for both people to run. Neither person can swing their arms in synchrony with their legs, thus slowing both people down. Not only that, if the faster person pulls too hard, the slower person tends to fall forward instead of running faster. So, is there actually a way of helping someone run faster than she normally could? --99.227.95.108 (talk) 05:51, 31 August 2012 (UTC)[reply]

Being chased by a monster should do it. Emotional states and high adrenaline can cause people to outperform their own personal standards, but I don't know that there's a way, short of attaching rocket skates to her feet, for another person to aid her in running faster. --Jayron32 05:53, 31 August 2012 (UTC)[reply]

I agree that holding her arm won't work. But, if the man runs behind the woman, and with both hands on her sides, pushing her, she'll go faster. I've tried that and it works, balance is good, but there is a danger of feet contact, so the man has to run with his feet further to the sides. I should point out that my lady has longer legs than I do, so if there was a scary monster, she most likely could outrun me. In any case, if the man is making the woman go faster by either towing or pushing, then he must be going slower than he could on his own. So, only do this if either a) you actually do love her, or b) you know for a fact that the scary monster only likes girls. I also point out that any test of strength, running speed, etc with girls is misleading. They do what they think will attract you, i.e., play the poor defenless female. Every girlfriend I've ever had has asked me to open jars etc. But they seemed to consume the contents just as much when I wasn't around. Wickwack121.221.84.138 (talk) 06:35, 31 August 2012 (UTC)[reply]