How the hell does Gravity work ?

[-IT-]

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.

Kudo's for you sir, that's a very nice explanation.

 

[beddo]

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.

Gravity is a force. Otherwise what causes that object to fall?

The curvature of space-time.

Also, the electromagnetic "force" is far far stronger than the gravitational "force", the only reason it appears not to be is because it exists in both positive and negative forms, which shield each other's effects.

The curvature of space-time doesn't explain why the ball would be moving without external force upon it.

 

[Soxafloppin]

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.

I prefer magic.

 

[More Fun To Compute]

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.

I prefer magic.

Magic is all right. When I'm want to use the internet though I find it easier to use a science powered computer than the magic powered mirror smeared with ox entrails.

 

[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.

Gravity is a force. Otherwise what causes that object to fall?

The curvature of space-time.

Also, the electromagnetic "force" is far far stronger than the gravitational "force", the only reason it appears not to be is because it exists in both positive and negative forms, which shield each other's effects.

The curvature of space-time doesn't explain why the ball would be moving without external force upon it.

Yes it does.
It's the curvature of space-time.
It's true that the curvature of simply space wouldn't explain the movement without force, but the curvature of space-time does.

 

[chefassassin2]

http://science.howstuffworks.com/question232.htm

http://en.wikipedia.org/wiki/Gravitation

http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html

 

[Seanchaidh]

As much as I can appreciate the many explanations of gravity in this thread, how gravity works is a slightly different question. What we've been able to do is label a phenomenon. We don't know how it works, just that it does work. Gravitons? That'd be convenient (though we'd still then want to know how gravitons work.) Curvature of spacetime? Ok, but what is the mechanism whereby mass has that effect? We understand that mass tends to go toward mass, and we have nice little equations describing the force of gravity between two objects (or the curvature of spacetime caused by an object) but we still don't know what gravity... is. We just know kind of what it does. We've labeled the question, not answered it. I don't really ever expect to know. What discovery could satisfy? Happily, I also don't think we need to know how gravity works. We only need to know what it does... and scientists do seem to have a firm grasp of that.

 

[uncle-ellis]

Same as electricity. INVISIBLE MAGIC!

 

[teutonicman]

Right so every object wants to pull ever other object in the universe towards its self. The denser the object the greater the pull.

 

[TheLastCylon]

Isaac. Fucking. Newton.

(at least that's what my science teacher told me when I asked him the same question)

 

[Martymer]

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.

This. The curving of space does, however, result in a force. The interesting question that science currently has no clear answer to is how objects with mass deform space around them. One theory (well, several, actually) suggests that it is because matter sends out quantum scale particles that (I *think*) interact with the fundamental strings of space-time, in a way that causes space-time itself to deform. These particles are what's called 'gravitons', but they have never actually been confirmed to exist.

 

[Maze1125]

Curvature of spacetime? Ok, but what is the mechanism whereby mass has that effect?

That's a never endding string.
"What is gravity?" "The attraction of two massive objects."
"How does that happen?" "Through the curving of space-time."
"How does that happen?" "Because of x."
"How does x happen?" "Because of y."
"How does y happen?" etc.

But that doesn't mean that it's pointless to ask the question, that's what science is all about, but there is always going to be questions left that no-ones found the answer to yet.

If you want an analogy for this... imagine you have a piece of paper, this is space and time. Now you put a weight on the piece of paper, obviously the paper sinks and creases cos there's a weight on it. That's the effect that a mass has on space and time. Now, say, if you put a tennis ball near it, it'll be drawn towards it. This... usually works better in real life when i try to explain it to people. I usually have paper then.

That analogy isn't very helpful as, for the ball to roll to the centre, an outside force is required.