How the hell does Gravity work ?

[Fronken]

Apparently the damn apple that fell on Newtons head started it all.

Just think of how much fun we could've had if Newton was at home sick that day...oh what could have been.

 

[Serinanth]

Ugh entanglement gives me a headache

 

[Zer_]

On topic, however, gravity works because of quantum physics. Every atom is made up of seperate elementary particles (protons, neutrons and electrons), but each of these is made up of even smaller particles (quarks, mesons, besons, etc.). Some of these particles, which every atom has at some fundamental level, are gravitons, which are basically attracted to each other according to Newton's Law of Gravitation. That's how gravity works.

Yeah.
Pity Einstein would disagree with that completely.

Gravity is not a force. Gravity is the curvature of space-time.
Objects don't move towards mass because of an attractive force, but because time is actually bent towards the mass.

He's not wrong, he just has it kind of backwards; the bending of spacetime gives rise to the force. It's potential surfaces that give rise to forces.

Spoiler: Slight Wall of Text

UnknownIncognito, I think we've been pretty tolerant so far (remember the irrelevant jokes thread?), but this is getting silly now. I'm asking you nicely, could you please just stop posting stupid threads that have no real merit for discussion? Thank you.

On topic, however, gravity works because of quantum physics. Every atom is made up of seperate elementary particles (protons, neutrons and electrons), but each of these is made up of even smaller particles (quarks, mesons, besons, etc.). Some of these particles, which every atom has at some fundamental level, are gravitons, which are basically attracted to each other according to Newton's Law of Gravitation. That's how gravity works. How they are attracted is similar to electromagnetism. There are four forces - weak, strong, electromagnetic, and gravitational, which are all basic properties of these fundamental particles (each type of particle has different properties, however). So these forces are what allow gravity, and it isn't just big things like planets, but everything in the universe is attracted to everything else. It's only noticeable at planetary sized levels though, since the force of gravity is minutely small for each particle, so only absolutely huge objects like planets have any sort of major gravitational pull.

That's basically it, as far as I can remember, but Wikipedia might be able to fill in any gaps since my own knowledge is based on a Quantum Physics course I did at A-Level.

[/thread]

Wait, so your QP course at A-level posited the existence of virtual particles that haven't even been confirmed yet?

That's the whole idea behind a theory. The graviton is now believed to be the key to a unified theory of the universe. No one has witnessed a graviton, that's why the LHC exists. Gravitons are not only very small, but it is believed that it is one of the only things that can freely travel from one dimension to another.

 

[Lukeje]

But, again, gravity isn't a force.
When an object is in freefall, it feels nothing. Freefall is in fact the natural state of affairs in the universe. Only when the fall is prevented, for example by the ground, is any force felt.

You don't understand what I mean. Einstein went into the '4th dimension' to explain the force of gravity. It's possible to go into higher dimensions to explain other forces such as the forces arising from Maxwell's equations. Thus, what we have defined as a 'force' is just a higher dimensional curvature.

 

[S.H.A.R.P.]

the thought experiment is, what happens if the sun just suddenly disappeared. Well light from the sun takes 8 min to get here. Newton thought that if the sun disappeared, the earth would immediately leave its orbit.

But Einstein said that since nothing can travel faster than light, then the earth wouldn't immediatly leave orbit, and from that he found a point for his space time continuum

This was demonstrated experimentally a few years ago by an astronomy team who deduced, by observing the behaviour of one of Jupiter's moons, that gravity does indeed travel at the speed of light.

Although! There are experiments where a tiny atom or something is split in half. Then one half is transported quite a distance away from the other half. Then on one half, some action is performed (like spinning it or something). The other half IMMEDIATELY performs the exact same action. So somehow information is traveling faster than light.

Einstein supposedly derided quantum mechanics as "spooky action at a distance". I'm not sure what experiment you are referring to here (and I'm sure I'd have heard about FTL communication) but we do know that quantum entanglement does not travel beyond the speed of light. What it does do is provide a completely secure mode of communication, which is why cryptographers are so excited about it. Why is it secure? It's impossible to eavesdrop on it without disturbing the original transmission.

Intriguing information. I think I've heard about the half atom, but I wasn't as interested at that time. Thanks for sharing your knowledge!

 

[Serinanth]

I saw somewhere that they think their might be over 10 dimensions.

I wonder what the sex will be like.

 

[the_hessian]

Go read a physics book... pah... but for you ludites, here we go, spoon fed by the internets...
http://zebu.uoregon.edu/~soper/Orbits/newtongrav.html

 

[Frank_Sinatra_]

You still here?

Every mass pulls weaker objects towards itself. The heavier the mass, the bigger gravity it has.

Simple. Wiki it next time.

Centrifugal force also has a part in gravity.

 

[Maze1125]

But, again, gravity isn't a force.
When an object is in freefall, it feels nothing. Freefall is in fact the natural state of affairs in the universe. Only when the fall is prevented, for example by the ground, is any force felt.

You don't understand what I mean. Einstein went into the '4th dimension' to explain the force of gravity. It's possible to go into higher dimensions to explain other forces such as the forces arising from Maxwell's equations. Thus, what we have defined as a 'force' is just a higher dimensional curvature.

Fair enough. I'll have to take your word for that as I've yet to take my studies that far.

 

[UltimatheChosen]

One explanation is that mass bends space time like a ball placed in the middle of a stretched out sheet warps the sheet. If you place another smaller ball on the sheet it will follow the curve in the sheet. The hard part is visualising what space time is, which is why people like Einstein are cool.

Probably all wrong or oversimplified.

That explanation is easy to understand... but it has the disadvantage that to visualize it, you have to imagine that the ball placed on the sheet is affected by gravity (to create the curvature). Unfortunately, I don't really know of a better example.

 

[shadowelancer]

Its god being angry at us. /sarcasm

 

[LeonLethality]

some please answer this question since science still hasn't.

My Theory: Magic

yes witchcraft it explains gravity wind electricity kittens and nukes


i hear gravity pulls harder on you the more you weigh so that means fat people are hogging the gravity

Nope, your weight changes depending on the gravity. Your mass is constant.

On the moon, you weight less than on earth, even if your mass is the same, because there is a smaller gravitational effect.

...I know... my best school subject is magic I MEAN science, i was making a funny >.> god

 

[YukoValis]

some please answer this question since science still hasn't.

Hasn't answered it? or you just can't understand it? I'll bet on the latter.

 

[Delixe]

The simple answer to the question is: "Because of Quantum"

Best to leave it at that.

 

[Overlord_Dave]

Although! There are experiments where a tiny atom or something is split in half. Then one half is transported quite a distance away from the other half. Then on one half, some action is performed (like spinning it or something). The other half IMMEDIATELY performs the exact same action. So somehow information is traveling faster than light.

You're talking about quantum entanglement. And no, it cannot transfer information faster than light (useful information anyway). It's a bit in-depth to get into here, but when two particles are 'entangled' one of their properties is randomised (usually their 'spin'). All that is known is that one particles has an 'up' spin, and the other a 'down' spin - which is which is completely unknown.

Then when you separate the particles, you measure one to have a spin of 'up', which means that 'magically' the other particle has a spin of 'down'. This may seem obvious but mathematically it means something has travelled faster than light.

However, the information is not useful, so does not violate Einstein's postulates (that info can't travel faster than light). Since the spins are random in the first place, then there is no way to communicate information with this method.

Einstein supposedly derided quantum mechanics as "spooky action at a distance". I'm not sure what experiment you are referring to here (and I'm sure I'd have heard about FTL communication) but we do know that quantum entanglement does travel beyond the speed of light. What it does do is provide a completely secure mode of communication, which is why cryptographers are so excited about it. Why is it secure? It's impossible to eavesdrop on it without disturbing the original transmission.

Yes that's what quantum entanglement is used for. But be aware that information DOES NOT travel faster than light. The entangled particles are kept next to each other and travel at normal (relativistic) speeds along a fibre optic cable, so no funny business.

The problem with unifying gravity and quantum mechanics is not so much the gravity doesn't operate at the quantum level - it's just that the effect is so small that it's not worth including. From a mathematical perspective, the problem is that time itself is viewed completely differently at the macro- and micro-scales, and so getting the theories to combine has proven impossible so far.

 

[Ancientgamer]

UnknownIncognito, I think we've been pretty tolerant so far (remember the irrelevant jokes thread?), but this is getting silly now. I'm asking you nicely, could you please just stop posting stupid threads that have no real merit for discussion? Thank you.

On topic, however, gravity works because of quantum physics. Every atom is made up of seperate elementary particles (protons, neutrons and electrons), but each of these is made up of even smaller particles (quarks, mesons, besons, etc.). Some of these particles, which every atom has at some fundamental level, are gravitons, which are basically attracted to each other according to Newton's Law of Gravitation. That's how gravity works. How they are attracted is similar to electromagnetism. There are four forces - weak, strong, electromagnetic, and gravitational, which are all basic properties of these fundamental particles (each type of particle has different properties, however). So these forces are what allow gravity, and it isn't just big things like planets, but everything in the universe is attracted to everything else. It's only noticeable at planetary sized levels though, since the force of gravity is minutely small for each particle, so only absolutely huge objects like planets have any sort of major gravitational pull.

That's basically it, as far as I can remember, but Wikipedia might be able to fill in any gaps since my own knowledge is based on a Quantum Physics course I did at A-Level.

[/thread]

Wait, graviton's have been proven? I thought that was still at the point of idle hypothesis?

I was about to post how awesome it would be if graviton theory was true but...well...awesome.

 

[megalomania]

The problem with gravity is that our understanding of it doesn't fit in with our understanding of attractive forces in the universe. eg Strong nuclear, Weak nuclear and elecromagnetic all make sense in terms of each other but gravity remains seperated.

Didn't you get the memo? The weak and electromagnetic forces were united by the discovery of the Z-boson a number of years ago

 

[ILPPendant]

Yes that's what quantum entanglement is used for. But be aware that information DOES NOT travel faster than light. The entangled particles are kept next to each other and travel at normal (relativistic) speeds along a fibre optic cable, so no funny business.

Yeah, sorry about that. It was a typo that slipped through my net.

 

[Zer_]

BTW the proposed reason why Gravity is such a weak force (at least to us it seems to be).

http://www.youtube.com/watch?v=mprHa68XpwI&fmt=18

 

[ironmace2.0]

You still here?

Every mass pulls weaker objects towards itself. The heavier the mass, the bigger gravity it has.

Simple. Wiki it next time.

Yes that is correct but I find it easiy to remember because my last name is newton no that isnt why I remember I just do.

My last name is really newton