Talk:Universe

Animation Functionality

The animation titled, "Animation illustrating the metric expansion of the universe." does not function as expected using Firefox 3.03 on the Macintosh. The browser hangs for a minute or two, then fails to display the animation.

76.195.163.180 (talk) 16:47, 18 October 2008 (UTC)Mark Mason

Relevance?

There are no outside sources independent of the subject matter declaring its relevance. Should it not be deleted, then? Shadowstalker (talk) 12:08, 11 August 2008 (UTC)

Should what be deleted? Gopher65_talk 15:06, 11 August 2008 (UTC)

The Universe, of course.

The article about the Universe, was what I was getting at. Seems as if there aren't any non-involved unbiased sources about it to prove it's relevant.Shadowstalker (talk) 17:19, 11 August 2008 (UTC)

— Arthur Rubin (talk) 16:53, 11 August 2008 (UTC)

I can't decide whether this user needs a welcome template or a trout-slapping. I think I will settle for a citation of WP:IAR. SHEFFIELDSTEEL^TALK 17:39, 11 August 2008 (UTC)

SI Unit usage

"SI units should be secondary, and we should use REAL SI units (Xm?)" (editing comment by Arthur Rubin)

Hi there!

I agree that Metres are a better unit than Kilometres.

But I was just wondering why SI units should be secondary? Just about every known person in the universe uses Metres, and pretty much only astronomers use light-years. Astronomers make up a pretty small percentage of people.

Which brings me to a point: The kind of people that use light-years to measure things are the kind of people who probably already have a pretty fair idea of how big the universe is. The remaining people who look at this article are probably the type who view the light-year as some kind of science-fiction unit, or possibly even a unit of time. For the sake of the majority of people (non-astronomers), it would seem reasonable to list SI units first, and then list Light-years next.

You might argue that the light-year is a natural unit for measurement, since many calculations of universal dimensions are based on measurements of the distance light has travelled, but I would counter that the unit is still inherently arbitrary in using the Earth-specific "year" as a point of reference.

What do you think? InternetMeme (talk) 06:32, 17 June 2008 (UTC)

In cosmology, light-years and years seem to be the natural units of space and time (respectively). In any case, they're most commonly used in publications and by experts in the field. "93 billion light-years (880 Ym)" seems better than "880 Ym (93 billion light-years)", especially since we'd need to link Ym somehow. — Arthur Rubin (talk) 07:03, 17 June 2008 (UTC)

I agree that the speed of light is a natural unit in cosmology (and any other field). But I see no reason whatsoever that the year should be thought of as a natural unit in any field outside of farming. It has no conceivable relevance whatsoever outside our planet as far as I can see. Therefore the light-day, light-month, or light-martian-year might all present themselves as equally suitable candidates. I think the only reason that the light-year could be seen as a natural unit would be due to many years of entrenched and arbitrary habit within the astronomical community. Is there another explanation? And if there isn't another explanation, why should any field outside of cosmology perpetuate the usage of this unit?

My main point, though is one of practicality: What percentage of Wikipedia's readership have an idea of the length of the metre/kilometre? I'd suggest over 75%. What percentage have an idea of the length of a light-year? I'd expect 10% at best. For this reason alone, it makes seven times more sense to present the diameter of the universe in metres/kilometres. Also, although SI prefixes are very useful, I think the usage of a reasonably familiar term such as "trillion" would be more useful than the "atto" prefix. InternetMeme (talk) 14:13, 18 June 2008 (UTC)

Perhaps we should Wikilink light-years? I think using non-SI terminology for SI units is specifically forbidden strongly discouraged by the MoS. As it stands, because of the short and long scales problem, "billion" and "trillion" are technically ambiguous, and Ym is probably recognized by fewer people than recognize light-year. I certainly think light-year should be primary, but that still leaves us with discussion the proper format of the metric unit.

880 Ym

880 septillion metres (note, spelling out the word and using the unit abbreviation is bad)

880 ×10²⁴ m 8.8 ×10²⁶ m

I think the last is probably most understandable. — Arthur Rubin (talk) 14:31, 18 June 2008 (UTC)

Indeed, I didn't even know what a Ym was until I started reading this discussion. If I'm talking about a number that big I use scientific notation, not Yotta. Using a prefix is just silly in this case. I suspect that no normal person knows what a Ym is, and that few abnormal people do. Think about it: when you talk about the distance between galaxies, what units do you use? Ym, or parsecs/light-years? I've *never* used metres or kilometres to talk about inter-galactic distances. I say "Alpha Centauri is the nearest star, and it's 41 trillion km away! That's like, 4 light-years or so. And the nearest major galaxy is two and a half MILLION light-years away!". That's the only way you can give any real sense of scale. Saying that Andromeda is 2.4*10^18 km away is meaningless to almost everyone, as is saying that it is 2.4 exakilometres away. "Say waaaa...?". People don't understand numbers bigger than trillion (shortscale), because they never come across them in their everyday lives.

I would also argue that light-year is a commonly understood term. People know what light is, and that it moves fast. They know what a year is. Putting the two together to get a *relative* measure of distance in their own mind shouldn't be that hard.Gopher65_talk 16:58, 18 June 2008 (UTC)

Well, in reply to the second-to-last post; people don't really understand numbers bigger than a billion either. So, rather than trying to relate that kind of distance on ANY scale, why not just write "The universe is big. Really big." And leave it at that? Also, I agree that the yotta prefix isn't very meaningful here. In fact, the entirity of what I'm suggesting here is that we try to convey a sense the size of the universe using only terms that are familiar to the average person. "billions of light-years" and "trillions and trillions of metres" are both difficult quantities to deal with, but at least metres are familiar to most people. Even miles would be more suitable than light-years in that respect.

In reply to the post above, I don't think it's the case that any normal person has any idea of the speed of light. For instance: How long does it take light to get from one end of the room to the other? How long does it take for light to get in to town? What about how long it takes to circle the globe? Now, if you could answer any of those questions without a calculator, then maybe I'm wrong. But I'm betting the average person has no idea of the answers. Therefore, using the speed of light as a reference is basically meaningless to the average person. As an aside, I think it takes light about a seventh of a second to get around the world : ) InternetMeme (talk) 11:59, 22 June 2008 (UTC)

The speed of light is a nanosecond a foot, of course, showing, once again that English units are preferable to metric.

</sarcasm> — Arthur Rubin (talk) 14:47, 22 June 2008 (UTC)

Well, when asked just how fast light is, I usually say something like "It takes us about 3 days to get to the moon. It takes light about 1.5 seconds. It's fast." (Or is 1.5 seconds for a round trip? I can never remember.) When dealing with an article like this, which is clearly a low-information beginner article, I think what we're going for is a relative distance. I mean, the distances involved are too much for any of us to truly understand. Even thinking about the distance between planets is mind-boggling if you try to hold it all to scale while you think about it. So we aren't trying to convey an absolute sense of distance, but rather a relative sense of distance.

I would use light-years as the primary unit, and metres in scientific notation as the secondary unit. But even if everyone agrees to that, it brings up another problem: a surprising number of people don't understand scientific notation. Of course, they won't understand any prefix bigger than trillion either. (Which is what I meant earlier. People know what trillion (short scale) is, even if they have difficulty conceptualizing it.) So What do we use? They don't know exactly what a light-year is, so it is just a random, relative unit to them. They don't understand big prefixes at all, so we can't say exametre or yottametre. They don't understand scientific notation, so we can't say 2.4*10^18, cause that is just a meaningless string of numbers to them. So since we have no meaningful way of really conveying these big numbers, I say we just use whatever units we are most comfortable with, and anyone who doesn't understand them can click the blue link and read up, just like the rest of us do on subjects that we aren't familiar with.Gopher65_talk 15:33, 22 June 2008 (UTC)

That would be like writing an article about horses, and saying "A horse is a four-legged brown animal that stands approximately 16 hands tall". Hands are the customary measurement unit for horses, so it'd be sensible to use those units, right? But of course, it wouldn't—because the only people that understand what that unit means are the kind of people that already know all about horses.

And in the same way—as far as the average person is concerned—Light-Years are sci-fi units used by spaceship-pilots that have no meaning beyond "incomprehensibly far". So listing the size of the universe in light-years is of no use to anyone, other than the people who are familiar with the unit. And the people who are familiar with the unit are the ones who already have an idea of how big the universe is, because they're astronomers.

Wikipedia is aimed at regular people, not just astronomers. Regular people shouldn't have to learn new units to know how big things are. They shouldn't have to learn how big a "hand" is to know the size of a horse, and they shouldn't have to learn how far a "light-year" is to know the size of the universe. InternetMeme (talk) 12:48, 25 July 2008 (UTC)

<removing indent> I'd agree, I really would, if you or anyone else could provide a measurement to Andromeda that the average reader will take to mean anything other than "incomprehensibly far". You can't. You know why? Because Andromeda really is incomprehensibly far! It is "far" beyond the human ability to understand. The only way we can attempt to quantify the distance to Andromeda is to use relative, meaningless units. Really, how far is a trillion kilometres? I have no idea. Absolutely none. 2 billion times the distance between Saskatoon and Edmonton? What the heck does that mean? About 6500 times the distance from the earth to the sun? But how far is that? All of these distances are meaningless, because humans can't understand such large values.

Our only option is to use a relative, meaningless unit. Because otherwise we end up writing out 42,000,000,000,000 every time we talk about the distance to the nearest star, because most "normal" people don't understand what scientific notation means. By your reasoning, that means we can't use scientific notation. Since most people don't understand large prefixes, we can't use those either (yottametre? Give me a break). Since most people don't seem to understand that a "million million" means that you multiple 2 "one million"s together, we can't use that either. Personally, I don't want to have to say that Andromeda is 2,365,000,000,000,000,000 kilometres away. Cause to me, that is just as meaningless as saying 2.365*10^19, or 23.65 exametres, or 2.5 million light-years. Are any of those meaningful? No.Gopher65_talk 20:22, 25 July 2008 (UTC)

Universe Exists IN time

Im fairly sure that the universe constitues all matter (space) . Not all time. Since a universe exists in Time, which could be argued to be never ending and always existing, surely the first paragraph of the article should reflect this. I am going to remove the word time from that sentence, if anyone wants to revert, I will understand, but I just feel that a Universe constitutes a snapshot of all that exists, at that moment IN time, a universe is not composed of Time, it merely exists within it. Time could in theory exist without the existance of a universe. Baaleos (talk) 14:35, 13 August 2008 (UTC)

No. Time is just another dimension of space. Length, Width, Time, and Height are the "proven" spacial dimensions. Time is as much a part of the universe as any of the other three. Gopher65_talk 19:21, 15 August 2008 (UTC)

Taken from the definition of time on Wiki -

Among prominent philosophers, there are two distinct viewpoints on time. One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence. Time travel, in this view, becomes a possibility as other "times" persist like frames of a film strip, spread out across the time line. Sir Isaac Newton subscribed to this realist view, and hence it is sometimes referred to as Newtonian time.[4][5] The opposing view is that time does not refer to any kind of "container" that events and objects "move through", nor to any entity that "flows", but that it is instead part of a fundamental intellectual structure (together with space and number) within which humans sequence and compare events.

I tend to side with the first belief, which states that 'Time is like a container, that events and objects move through.' (Wording taken from the second belief, which is opposed to the first). If the Universe is an object, then it would have moved and progressed through Linear Progression. If it had a birth, there would have been a time before its birth. If the universe did not exist at this point in TIME, and there was no TIME, then the universe would not have Progressed towards a birth. This would suggest that Time can operate independant of a Spacal (Matter) Component. Since we all exist, and the universe did infact come into being, this means that time progressed even without the universe around it existing. Azazeel (talk) 12:46, 10 September 2008 (UTC)

I think you need to square the "separateness" of time from space with the connection revealed by general relativity. I've restored the wording in the article for the time [sic] being. Cheers, --PLUMBAGO 13:06, 10 September 2008 (UTC)

Adding to what Plumbago said, pulling up a Newtonian view of reality is meaningless since Newton was, well, wrong. Or at least his viewpoint was so narrow and his work so incomplete that it is useless except in very specific circumstances (circumstances like our everyday lives;)). Along the same vein, what philosophers say about time is irrelevant. Philosophers deal in wishes, fantasy, and imagination, not in what is real, or in what is true. All that matters for an argument like this is the evidence that has been gathered using science, and right now that evidence *all* points toward space and time being part and parcel. Time is just another spacial dimension, not some separate entity. Gopher65_talk 23:57, 11 September 2008 (UTC)

Energy is not three-dimensional and when it travels through three dimensions it creates time at a rate of 1 second per 299,792,458 meters. You're welcome. polpoint_talk 2:15pm, 10 October 2008 —Preceding unsigned comment added by 12.110.164.222 (talk) 18:16, 8 October 2008 (UTC)

Commendable

I've made no contributions to this article, so I feel entitled and obliged to comment "Superb work! Well informed, balanced, pedagogical, up to date, more so on all accounts than any other overview on the subject. Bravo!" Kind regards, Ryttaren (talk) 08:56, 15 September 2008 (UTC)

That's very kind, Ryttaren — what a wonderful and encouraging surprise! :) Thank you, Willow (talk) 01:47, 17 September 2008 (UTC)

Exists -> Existance

I noticed that the Exists link goes to Existential quantification, but I wonder if Existence would be a better link?

Our universe being pulled towards another universe?

Astronomers have stumbled upon an unexplained two-million-mile-per-hour sideways shift in the universe toward a colossal, unseen, unknown gravity source beyond the horizon of the observable universe. [1] - article suggests it's another universe. Doug Weller (talk) 08:49, 26 September 2008 (UTC)

Surely it can't, by definition, be "another" universe: the quote mentions "observable" universe. --Old Moonraker (talk) 09:06, 26 September 2008 (UTC)

Right. This simply means that there is a limit to how far we can see, because of the speed of light (13 billion light years or so). However, they can see Galaxies far away from us being affected by things beyond our light horizon (ie, more than 13 billion light years away). Gopher65_talk 06:06, 29 September 2008 (UTC)

Size vs. mass chart request

I'd like to suggest adding a plot to this page that shows the (logarithmic) distribution of object dimensions versus mass, somewhat like the following image:

http://universe-review.ca/I01-00-massize.jpg

(except with data points rather than pictures). The excluded ranges are also informative, so they would be good to include as well. I've seen this illustrated in a couple of science books and the data is available from certain references, but I haven't seen a GDFL'd version. Is anybody interested in putting a chart like this together? Thank you!—RJH (talk) 16:35, 9 October 2008 (UTC)

There are a lot of problems with that image:

• The electron has no detectable size. I'm not sure what the best current upper bound on its radius is, but it's enough to put it well inside the region marked "ruled out by quantum uncertainty." The proton has a radius which is determined by the strong force, and it's slightly outside that region, not on the boundary.
• The mass and radius of the visible universe place it inside the region marked "ruled out by gravity."
• The chart implies that the density of water is somehow related to the electron mass and the "quantum uncertainty" line. This is not true and it makes no sense—for one thing, the density of water is dominated by the mass of the nuclei, not the electrons. This is a pretty significant numerical error, and it looks like both the electron mass and the water density have been shifted to make them appear to meet up.

Once you remove all the mistakes, I'm not sure there's enough useful information left to make the chart worthwhile. -- BenRG (talk) 23:00, 12 October 2008 (UTC)