Talk:Gravity

Suggesting Formulas

How about adding pictures of formulas explaining the scenario of a falling object in different scenarios? — Preceding unsigned comment added by 88.65.75.71 (talk) 21:39, 9 August 2012 (UTC)

Sugesting pictures

I think this article needs a picture of a 3D simulation of gravity, something like this:
Gravity in 3D
3D gravity
I don't think these specific pictures are allowed here, but if someone can find a similar picture that is legal to use it would be a nice addition to the article
Sebbes333 (talk) 19:20, 19 July 2012 (UTC)

History

Gravity was first discovered by a Hindu astronomer who thought of the idea of gravity but did not give it a specific name or meaning. Varahamihira observed the effect of gravity on heavenly bodies as well as things that are coming back to the Earth.

on gravity was Brahmagupta. He was a Hindu astrologer who commented that gravity, as a concept, is a natural affinity or part of the natural order of the world. He even compared it to elements like water and fire.

The 11th century saw the coming of another Hindu astrologer named Bhaskarachaya. He continued the efforts of Brahmagupta. He also wrote a book that mentioned gravity. This book is entitled “Siddhanta Siromani.”

Another worthy contribution of the Hindus on gravity was by giving it a definite term. The term was in Sanskrit and was called “Gurutvakarshan.”

Years, decades, and centuries passed before the Christian world became interested in gravity as much as the Hindus. The Western Christian world became interested in the sciences after the Renaissance, a period of revival of classical knowledge. Although gravity is not particularly mentioned in classical Greek or Roman texts, some scientists began to rediscover ancient beliefs about the world that led to the rediscovery of gravity.

Christian gravity features many people who are famous and familiar with modern people. These people are better known compared to their Hindu counterparts due to the dominant Western history and traditions in the world.

One of the leading figures is Nicholas Copernicus who proved that the Earth is round rather than a flat surface. This contradicts the thought that a vessel traveling the oceans would fall off the “world’s edge” as once believed. All things on Earth are held down by gravity, even in a spherical shaped body like a planet.

Galileo Galilee followed Copernicus in the 17th century. Galileo was known for his famous experiment of dropping two materials with different weights at the top of a tower. He also contradicted a classical teaching by Aristotle, a leading Greek philosopher.

Meanwhile, the most famous scientist focusing on gravity is Sir Isaac Newton. Newton’s discovery was founded from Robert Hooke’s suggestion that gravity is related to distance and its inverse square. Sir Newton also developed the mathematical formula and established the law of gravity.

Another leading and famous figure is Albert Einstein who founded the Theory of Relativity. Like Newton’s, Einstein’s contributions are considered to be the classic or the dominant teaching when it comes to relativity.

Western Europe’s contribution on gravity ideologies are those taught in schools today. In addition, these Western figures are able to express gravity in a formula (specifically a mathematical one) to make gravity more realistic as opposed to an abstract concept. Gravity is a constant element in our reality, but it is still very abstract since we can only feel or experience it even in everyday life.

Both Christian and Hindu gravity concepts have played an enormous contribution to the understanding of gravity.

Read more: Difference Between Christian Gravity and Hindu Gravity | Difference Between | Christian Gravity vs Hindu Gravity http://www.differencebetween.net/miscellaneous/religion-miscellaneous/difference-between-christian-gravity-and-hindu-gravity/#ixzz20rvnxLws — Preceding unsigned comment added by 218.189.138.50 (talk) 09:05, 17 July 2012 (UTC)

the speed of gravity

There is no mention of the speed of gravity. For example if we removed the sun how much time would it take to have the heart flung out of the previous solar system. --81.84.152.156 (talk) 19:32, 27 April 2010 (UTC)

Well since gravity doesn't have any spped, it makes sense that there is no mention of it. Gravity-in super amateur (ei, me) terms, accelerates an smaller mass towards a larger mass. this acceleration varies, depending on the mass of the two abjects. —Preceding unsigned comment added by 38.115.132.20 (talk) 20:36, 12 May 2011 (UTC)

Gravity is a force that acts on a distance so if you change the mass distribution at point A the force changes at point B but unless point A is point B the force doesn't change instanly. I understand that if Sun would disapper now, it would take roughly 8 minutes before it would be felt on Earth. That is to say the "speed" of gravity would be c. I might be mistaken but it certainly can't be larger than c because that would violate Einstein causality. 88.148.148.97 (talk) 20:20, 4 December 2011 (UTC)

The above is only true if the force of gravity is "carried" by virtual force-carrying particles in the same way that the electromagnetic force is carried by photons. However, gravitons have not yet been discovered, so the matter is still up for debate. This is in fact hinted at in the article. ~ Lhynard (talk) 22:18, 4 December 2011 (UTC)

Not true. Even in general relativity, gravity, with no gravitons or any quantum stuff, moves at the speed of light. In fact Einstein's motivation for developing general relativity came from realising that, unlike electromagnetism, Newtonian gravity wasn't consistent with special relativity because in Newtonian gravity information travels infinitely fast (ie the strength of a gravitational field in Newtonian gravity is dependent only on the present mass distribution, not any information about where mass may have been in the past). — Preceding unsigned comment added by 92.27.55.215 (talk) 20:57, 18 May 2012 (UTC)

Gravity 1 & Gravity 2

If you drop an object here on earth, it gets draged around with the planets spin(we know this because when we drop something it falls exactly where we expect it to even though the planet is spinning), at what distance does this happen? is this drag relevant to the moon? Enertia is in a line, but the planet is spining. Im honistly starting to believe in two gravities?

If you believe it's Coriolis_effect then what keeps hot air baloons going around with the planet? "Gravity also drags?"! gravity drags works with atomic precision

Paul G Griffiths, Bristol UK 2011
—Preceding unsigned comment added by Gafferuk (talk • contribs) 21:17, 11 May 2011 (UTC)

Thank you for your interest in Wikipedia's article on Gravitation. However, this talk page is not an appropriate place for asking questions about the article's subject, or for proposing or discussing alternative theories about how gravity might work. The purpose of Wikipedia articles' talk pages is to propose and discuss ways in which those articles might be improved. I have therefore taken the liberty of copying your questions across to Science Reference Desk and (partly) answered them there.

David Wilson (talk · cont) 00:01, 12 May 2011 (UTC)

An object dropped from a hight of 1m takes less than half a second to reach the ground (ignoring air resistance and buoyancy). You are right about inertia making the object keep going in a straight line while the earth turns away from it, but in the time it takes for the object to land, the difference will be tiny. This doesn't have anything to do with the moon; instead, it (and any other object in orbit around the earth) is essentially falling down, but moving forward fast enough that it always misses the earth - see Orbit for more details. Wardog (talk) 10:55, 25 February 2012 (UTC)

Morgan Freeman

I saw Morgan Freeman on a show the other night and he said he wasnt sure if gravity works or not in infintesimally small spaces. I want to add that he said that to the lead paragraph but there is a lock on the pagein the upper right hand corner that I cann ot unlock! — Preceding unsigned comment added by 207.238.152.3 (talk) 19:39, 15 July 2011 (UTC)

Morgan Freeman is an actor. As good of an actor he is, it does not make him a very reliable source. A peer-reviewed research papaer would work much better.--137.146.143.108 (talk) 15:34, 8 February 2012 (UTC)

I'm guessing that the op was thinking of Freeman Dyson. 209.252.235.206 (talk) 10:14, 17 February 2012 (UTC)

More likely Morgan Freeman reading from a script on Through the Wormhole on the Science Channel.--Bainst (talk) 06:23, 2 March 2012 (UTC)

a loop hole in newtons theory of gravity..

if i fire a cannon ball right up in the air (neglecting air resistance) it is but obvious that it fall down. sir newton gave inverse square law, according to which gravitational force is inversely proportional to square of distance between the two objects. now as i fire the cannon ball in the air, the distance is going to increase, and so the square, so as per the formula gravitation force should decrease, but it does not happen. ball falls returns to earth. if the force is decreasing as per increase in height according to the formula, then what is making the ball to return back to earth. the answer to this is very simple, its gravity but this force is not exerted by the earth(it according to me) but it is the layer of atmosphere around the earth. --Jokerthedarknight (talk) 13:59, 9 January 2012 (UTC)

The force due to gravity would lessen as the cannon ball went higher, however, it would not completely disappear. The average cannon cannot launch a cannonball high enough that it can escape Earth, however, space shuttles can get to space precisely because they can get "high enough" that Earth's gravity becomes insignificant. 209.252.235.206 (talk) 10:16, 17 February 2012 (UTC)

First, this page is for discussing the article, not the topic itself. Questions about the topic can be asked at the Science Reference Desk. However, the statement above is incorrect. Anything that is in orbit, like the shuttle or the International Space Station, has not 'escaped' the gravity of Earth. The gravitational force is still quite significant there, which is why the object stays in orbit. It is because of its speed that it doesn't return to the ground. Check out the articles on orbital velocity and Kepler's Laws for more explanation. PhySusie (talk) 15:52, 25 February 2012 (UTC)

It does apply and happen. You just need to calculate distance change from the centre of each spherical mass. It doesn't change much and the gravity between the two is inversely proportional to the square of the distance that hasn't changed much. 99.251.114.120 (talk) 03:00, 3 May 2012 (UTC)

Edit request on 20 January 2012

Under Specifics / Earths Gravity the following sentence is as follows,

"Thus, an object starting from rest will attain a velocity of 9.81 m/s (32.2 ft/s) after one second, 19.6 m/s (64.4 ft/s) after two seconds, and so on, adding 9.81 m/s (32.2 ft/s) to each resulting velocity."

I think the 19.6 m/s should be changed to 19.62 m/s

It's minor but the the gravity constant of 9.81 m/s is precise to two decimal places and I think the 19.6 m/s value given should also be precise to two decimal places.

209.82.26.132 (talk) 22:48, 20 January 2012 (UTC)

Sounds reasonable to me.  Done, thanks. Adrian J. Hunter^{(talk•contribs)} 02:28, 21 January 2012 (UTC)

Missing: The physical expression of Gravition force.

I think it is truly astounding that the most basic formula for gravitation is missing in this article !:

Fg = G m1 m2 / r^2 — Preceding unsigned comment added by 213.93.217.25 (talk) 11:22, 3 March 2012 (UTC)

I also am very confused by this... A more thorough search revealed to me that this equation is located in the pages "Newton's Laws of Universal Gravitation" and "Equations for a falling body" but it's pretty confusing to not have them on the gravitation page. Maybe someone could at least add a sentence along the lines of "for the equation which describes the force due to gravity on an object in a gravitational field see..." — Preceding unsigned comment added by 50.137.182.79 (talk) 20:57, 2 November 2012 (UTC)

Universe-Energy-Mass-Life Compilation

From http://universe-life.com/2012/02/03/universe-energy-mass-life-compilation/ “Since gravitation is the propensity of energy reconversion to mass, and energy is mass in motion, gravity is the force exerted between mass formats.” (and extent depends also on distance-configurations...)

Dov Henis Dov Henis (talk) 03:21, 27 March 2012 (UTC)

This appears to be an unorthodox theory which has yet to be accepted by anyone other than its proposer. As such, it's not appropriate material for coverage in a Wikipedia article.

David Wilson (talk · cont) 04:17, 27 March 2012 (UTC)

Edit request - "their mass"

Lede contains the phrase "their mass". Should this not be "their masses". When the adjective is plural the noun should be also. This refers to the combined **effects** if both masses not combined into one singular mass. 99.251.114.120 (talk) 03:40, 14 April 2012 (UTC)

Done. Ruslik_Zero 16:28, 14 April 2012 (UTC)

What is it?

All these theories about the effects of gravity but not one theory mention about what gravity actually is and/or the mechanism of how it works. It would appear there may be no theories and the article should state that. If theories exist they should be mentioned in the article. Most of this article apears to be fluff on abstract and unrelated downstream topics based on only the effects of gravity. 99.251.114.120 (talk) 13:40, 1 May 2012 (UTC)

Nobody knows! The best guess we have is that gravity works by atoms exchanging "virtual particles": why this creates a force anyway is very hard to understand. The only reason we think this might be the case is because it's worked for all the other forces we know, but if you do the same maths with gravity, for technical reasons it doesn't work. There are thousands of physicists working to resolve this problem. However, Einstein's equivalence principle suggests that gravity isn't really a force, it is purely an effect of the geometry of spacetime. There are plenty of physicists who believe that there are no virtual particles because (a) the Einstein principle makes gravity different, (b) the maths doesn't work for gravity, and (c) despite dedicated experiments, nobody has seen the elusive gravity particle. — Preceding unsigned comment added by 92.27.55.215 (talk) 21:08, 18 May 2012 (UTC)

I agree that this article is very inaccessible to a layman who comes here to get the answer to the question "What causes gravity?" If we know, the article should say so. If we don't, it should say we don't. --Westwind273 (talk) 04:35, 29 May 2012 (UTC)

Gravitation

Gravitation is nothing else but a black sphere in the center of each star and planet.www.dimension-theory.com[[www.informa-invent-suply.se] Since Wikipedia does not allow any pictures on th is page. I will refer to the above 2 links. NOTICE HOW THE GRAVITATION FACTOR IS MEASURED FROM THE CIRCUMFERENCE OF THE SPHERE PARABOLICLY AS ITS CENTER. Private reasearcher --Bjorn Quarzell (talk) 14:29, 12 June 2012 (UTC)--Bjorn Quarzell (talk) 14:29, 12 June 2012 (UTC)Bjorn Quarzell.

Question

Something bothered me in the article when it came to "...Galileo showed that gravitation accelerates all objects at the same rate." etc. When looking at the formulas for calculating gravity it seems to me that the resulting force is equal to the total mass of BOTH objects. This would mean that a 10kg hammer will fall faster than a 1kg hammer, the reason being the total mass of the 10kg hammer + the earth is greater than the 1kg hammer + the earth. It is probably not easy to measure but logic and the formulas suggest to me that this must be actually be true. So why is it suggested that all things fall at the same rate when that would appear to contradict the newton formulas? Shouldn't somebody make a note on this point?

The same would apply if you use Einsteins theory, the object would have its very own (though very small) effect on space time which must add to the same effect of the earth itself. Strangely in every picture of space time warping I've ever seen only the larger body was assumed to warp space-time and cause a gravity well. Strange. — Preceding unsigned comment added by 62.154.226.26 (talk) 11:51, 13 February 2013 (UTC)

The Galileo example is a simplification that treats the mass of the earth including all the hammers on Earth as well as axes, screwdrivers, and can openers.—GraemeMcRae^talk 21:47, 13 February 2013 (UTC)

Then the comment "Galileo correctly postulated air resistance as the reason that lighter objects may fall slower in an atmosphere." is actually wrong, that is what I'm getting at. The maths from both Newton and Einstein don't allow any two bodies to feel the same force unless they have the exact same mass at the exact same distance, correct? That is what bothers me about the article. — Preceding unsigned comment added by 62.154.226.26 (talk) 07:09, 14 February 2013 (UTC)

Smallest particle where Gravity is measurable

I am just a layperson who is fascinated with the creation of the Universe (the final frontier). I read various theories, such as from nothing came something, but where my lack of knowledge puzzles me, is this; how do these dust particles in space the size of a pinhead (once they collide) start to stick together to eventually form planets? Do these dust particles have gravitational pull? What is the smallest size that has ever been measured to have gravitational pull...........an atom? Again, I am no scientist, but if atoms have gravitational pull, why wouldn't larger objects on my desk be drawing smaller objects to them to 'adhere' to each other?

Thanks to anyone whom will respond to me in a lay person's language.

Beaconmike (talk) 03:54, 24 July 2012 (UTC) The shortest distances on which gravity has been measured is something like tenths (maybe hundreds by now) of a millimeter. But even in those cases the gravitating devices are cm's across.TR 09:29, 6 November 2012 (UTC)

''MOVE ARTICLE to gravity

"Gravity" is a more common term than "gravitation" WP:COMMONNAME Ticklewickleukulele (talk) 00:11, 28 August 2012 (UTC)

No. In casual discussion, gravity and gravitation are often used interchangeably. However, gravitation is an universal force exercised by two bodies onto each other and gravity is a resultant force: Earth's gravity; gravity on the surface of the Earth. --Hartz (talk) 06:56, 4 November 2012 (UTC)

The cause of gravitation is unknown

I think we should mention in the lead that we do not know the cause of gravitation. We can observe gravitation and we can calculate it, but we do not what is the true cause of gravitation. We have noticed that it is assosiated with large bodies such as the Earth or the Sun, but we do not know why these objects create gravitation around themselves. Can the theory of relativity answer this? The cause of gravity is the curvature of spacetime? Unproven. --Hartz (talk) 15:31, 2 November 2012 (UTC)

Yes, the existence of a Wikipedia user named Hartz is also unproven. (These posts could have arisen through random glitches in the Wikimedia software.) We also do not know why charged objects create an electric field. Or why energy is conserved? Or why the laws of nature are time translation invariant? (the last two are equivalent though) Or why the standard model has SU(3)xSU(2)xU(1) gauge symmetry. Science is not in the business of explaining why thing work the way they do, but of explaining how they work the way they do.

What we do know is that general relativity, by describing gravitation as curvature of spacetime rather as a Newtonian force, gives a better description of observed physics than Newtonian gravity. Your GPS proves this everyday (if you have one).TR 09:27, 6 November 2012 (UTC)

suggestion - 07/11/2012

the article itself lacks information on the differentiation of gravity on other planets and star systems. A section devoetd to neutron stars and black holes might be a nice addition. — Preceding unsigned comment added by Thedarkknight1 (talk • contribs) 19:21, 7 November 2012 (UTC)

Vandalism

Someone added " Lilia is always right about gravity. " to the first paragraph. This is inaccurate and unsourced; it is likely Lilia is only sometimes right about gravity. I suggest removing this change. Ianjk (talk) 23:45, 2 February 2013 (UTC)

• done - thanks! PhySusie (talk) 23:52, 2 February 2013 (UTC)

Incorrect drawing in relation to curved spacetime.

The gravitic well, is defined accorded to a point mass at it´s center. There is no point mass, there are gravitic effects within that mass and when you resolve the equations, the attraction becomes equivalent in all directions, away from the center, implying an outwards force, instead of an inwards force. Drawn, that implies that the tip in the center, is higher energeticly then outside the gravitic well. A sinc curve, without the side lobes, is the real curvature.