Is Gravity Really a Fundamental Force?

[maverick_starstrider]

I'm not sure how the statement "space is matter/energy" makes sense. Space is what contains matter/energy. It's some kind of dynamical background everything takes place on. If space actually was something, you could ask even further: What contains space?

Science Fiction tell us this this is obviously subspace.

 

[Polyrhythmic]

Hah. Right.

 

[Naty1]

Can someone help me understand in a way that I can comprehend why we are some certain gravity is a fundamental force?

Maybe a little bit:
From nothing, thanks to a big bang, everything, EVERYTHING, we observe popped out or had it's origins in "nothing"...maybe a virtual particle fluctuation of some type...nobody knows...nor what caused the big bang nor ANY of the 'fundamental' entities which emerged.

It is believed that from the big bang, spontaneous symmetry breaking led a unified (combined) entity of some type to breakdown into the entities we see today...and which now eappear as separate "fundamental" entities, those that appeared almost togther...forces, mass, energy, space, time,etc, and later all the particles we observe.

We don't have a complete theory of gravity...Einstein's GR is the large scale view and Quantum mechanuics offers some small scale view of gravity...but combining them so they agree is as yet incomplete...right now that unification effort falls under the general heading "quantum gravity".

You can check out any of these terms in Wikipedia.

 

[Polyrhythmic]

[...] Quantum mechanuics offers some small scale view of gravity [...]

How does quantum mechanics offer a small scale view of gravity? Quantum mechanics tells us nothing about gravity. The problem is to apply the formalism of quantum mechanics on gravity, to quantize gravity. But it has not been solved so far.

 

[Haroldingo]

You can't say that gravity is just something that forces certain large objects of mass in space together because of how gravity affects us on earth.

See I think a lot about gravity because of the potential that comes with understanding it. Gravitational travel, and ways of generating energy through existing forces such as gravity, is something that interests me a great deal.

I see what you're saying and on some levels I agree, to me it feels more likely that gravity is an electrical force. All particles in matter have electrical energy and every interaction that objects have with one another is electrical because electricity within particles is the key to their information. If we assume for a moment that gravity is electrical particles trying to establish a meak connection then gravity really comes across a sort of magnetism.

I mean this in a way similar to how atoms are kept in perfect balance by electro-statical forces.

Of course I'm tired, it's late, and that means that my lack of knowledge for this subject is shining through more than ever. I really just know words, and that's why when I put them together to try and establish a proposition on a forum like this, full of people who know their stuff, it's really just to find out some more information that can help me develop my capacity for this subject.

 

[Drakkith]

You can't say that gravity is just something that forces certain large objects of mass in space together because of how gravity affects us on earth.

We've sent men and spacecraft to the moon, spacecraft to every single planet in the solar system and to some non planets as well, we can see the effects within other solar systems and how they interact, and all of it points to gravity and all other forces to be exactly the same everywhere.

See I think a lot about gravity because of the potential that comes with understanding it. Gravitational travel, and ways of generating energy through existing forces such as gravity, is something that interests me a great deal.

We already understand the effects of gravity. I can't see any realistic way of generating gravitational travel nor energy (barring things like hydroelectric power and fusion inside stars and etc). I hope you aren't referring to something similar to "free energy" devices.

If we assume for a moment that gravity is electrical particles trying to establish a meak connection then gravity really comes across a sort of magnetism.

That doesn't make any sense.

I mean this in a way similar to how atoms are kept in perfect balance by electro-statical forces.

I can't see any relation between how atoms behave and gravity. Could you elaborate?

 

[Debt]

i believe elec-stat force works like em and gravity. the four forces work their jobs and i believe that they are a lot alike. desite the diff in scale. they hold everything together.

 

[Drakkith]

i believe elec-stat force works like em and gravity. the four forces work their jobs and i believe that they are a lot alike. desite the diff in scale. they hold everything together.

The electro-static force is another name for the electromagnetic force. While the four forces are similar in function, they are still very different in the details. For example, the EM force has 2 charges, + and -. Gravity, if treated similarly, only has 1 charge. On the flip side, the strong force has at least 3 different charges, or "colors", that quarks can have.

 

[Haroldingo]

We've sent men and spacecraft to the moon, spacecraft to every single planet in the solar system and to some non planets as well, we can see the effects within other solar systems and how they interact, and all of it points to gravity and all other forces to be exactly the same everywhere.

Yes, but not always with the same strength? In some places gravity is stronger than others. I mean that has nothing to do with my initial response but ah well.

We already understand the effects of gravity. I can't see any realistic way of generating gravitational travel nor energy (barring things like hydroelectric power and fusion inside stars and etc). I hope you aren't referring to something similar to "free energy" devices.

Well if we could use gravity to pull things together then 1) Nuclear fusion would be possible 2) We could contain without electromagnetism.

That doesn't make any sense.

Electricity is formed by a charged particle right? All I mean to say is, would it be possible that the type and power of the charge from every particle affects how they attract others? In this sense Gravity could work on a much larger scale, just like magnetism but with a basis in motion. Everything with gravitational pull has a constant motion.

I can't see any relation between how atoms behave and gravity. Could you elaborate?

That's the point, and that's the problem. Quantum physicists and Cosmologists are still looking for a way to quantify everything large by everything small. The idea I was proposing that atoms can be related to much larger systems like planetary orbits if we assume that there is a correlation between the forces at work in an atom and the forces at work in a planetary system.

 

[Haroldingo]

The electro-static force is another name for the electromagnetic force. While the four forces are similar in function, they are still very different in the details. For example, the EM force has 2 charges, + and -. Gravity, if treated similarly, only has 1 charge. On the flip side, the strong force has at least 3 different charges, or "colors", that quarks can have.

Really? I always thought that Electro magnetism is a force generated by moving charges, and electro static is from startic charges?

 

[Drakkith]

Really? I always thought that Electro magnetism is a force generated by moving charges, and electro static is from startic charges?

Back in the 18th and 19th centuries (1700's-1800's), it was believed that the Magnetic and Electric forces were two different forces. However experiments showed that a magnet can generate electric forces, and an electric force can generate a magnetic force. Eventually it was realized that both were a manifestation of the same force, the Electromagnetic force. Similarly it was realized that the Weak force and the Electromagnetic force could be combined as well, into the Electroweak force.

 

[Polyrhythmic]

Yes, but not always with the same strength? In some places gravity is stronger than others. I mean that has nothing to do with my initial response but ah well.

The gravitational laws are the same everywhere. Gravity is just stronger in the presence of heavier objects.

Well if we could use gravity to pull things together then 1) Nuclear fusion would be possible 2) We could contain without electromagnetism.

But gravity is much weaker than electromagnetism. By a huge amount, the difference is around the order of 10^40.

Electricity is formed by a charged particle right? All I mean to say is, would it be possible that the type and power of the charge from every particle affects how they attract others? In this sense Gravity could work on a much larger scale, just like magnetism but with a basis in motion. Everything with gravitational pull has a constant motion.

Gravity pulls, that is correct and nothing new. What do you mean by constant motion?

That's the point, and that's the problem. Quantum physicists and Cosmologists are still looking for a way to quantify everything large by everything small. The idea I was proposing that atoms can be related to much larger systems like planetary orbits if we assume that there is a correlation between the forces at work in an atom and the forces at work in a planetary system.

Even though the idea seems tempting, there's no reason to assume that atoms behave in any way like planetary systems. The introduction of quantum mechanics has definitely destroyed any possibility for such a view.

 

[Drakkith]

Yes, but not always with the same strength? In some places gravity is stronger than others. I mean that has nothing to do with my initial response but ah well.

The amount of gravity an object has is DIRECTLY proportional to its mass. Gravity has never been shown to vary anywhere. Only the amount of mass nearby to our probes and spacecraft changes as they move around.

Well if we could use gravity to pull things together then 1) Nuclear fusion would be possible 2) We could contain without electromagnetism.

The universe already does that via stars. The amount of mass required for gravitational confinement is staggering to say the least. Honestly just throwing up solar panels or harnessing the heat from the sun is doing what you are talking about anyways.

Electricity is formed by a charged particle right? All I mean to say is, would it be possible that the type and power of the charge from every particle affects how they attract others? In this sense Gravity could work on a much larger scale, just like magnetism but with a basis in motion. Everything with gravitational pull has a constant motion.

Well, with a charged particle, two opposite charges bound together, for example in a Hydrogen atom, effectively cancel each others charges and make the atom overall neutral. However gravity only has one "charge" so to speak. Also I don't understand what you mean by everything with gravity has a constant motion.

That's the point, and that's the problem. Quantum physicists and Cosmologists are still looking for a way to quantify everything large by everything small. The idea I was proposing that atoms can be related to much larger systems like planetary orbits if we assume that there is a correlation between the forces at work in an atom and the forces at work in a planetary system.

But you are missing a very key point here. There is no correlation beyond vague similarity between planetary orbits and atomic orbitals. Electrons are not little spheres going in circles around the nucleus. They are wave packets that occupy set orbitals based on the energy level of the electron. (Warning: Incoming terrible explanation from an amateur) Imagine a guitar string with both ends wrapped around touching themselves so it forms a circle. If you could pluck the string the whole thing would vibrate as a "Standing Wave". Take this analogy, make it into a 3d version like a sphere, and you have an electron orbital. Each energy level can only vibrate at a specific frequency. The others don't "fit".

 

[Haroldingo]

The amount of gravity an object has is DIRECTLY proportional to its mass. Gravity has never been shown to vary anywhere. Only the amount of mass nearby to our probes and spacecraft changes as they move around.

Ah. Black holes. As far as we know their gravitational pull isn't from a huge amount of mass?

The universe already does that via stars. The amount of mass required for gravitational confinement is staggering to say the least. Honestly just throwing up solar panels or harnessing the heat from the sun is doing what you are talking about anyways.

So you're saying that energy via nuclear fusion is useless? Harnessing the heat of 100 Million degrees centigrade is nothing to be laughed at. We wouldn't need fossil fuels at all.

Well, with a charged particle, two opposite charges bound together, for example in a Hydrogen atom, effectively cancel each others charges and make the atom overall neutral. However gravity only has one "charge" so to speak. Also I don't understand what you mean by everything with gravity has a constant motion.

Ok :) What I mean by everything with gravity having constant motion is that all planetary bodies spin, or turn, or whatever. The same, supposedly, is true for black holes but on a much more extreme level.

But you are missing a very key point here. There is no correlation beyond vague similarity between planetary orbits and atomic orbitals. Electrons are not little spheres going in circles around the nucleus. They are wave packets that occupy set orbitals based on the energy level of the electron. (Warning: Incoming terrible explanation from an amateur) Imagine a guitar string with both ends wrapped around touching themselves so it forms a circle. If you could pluck the string the whole thing would vibrate as a "Standing Wave". Take this analogy, make it into a 3d version like a sphere, and you have an electron orbital. Each energy level can only vibrate at a specific frequency. The others don't "fit".

I understand Schrödinger's equation, energy levels of electrons and orbits of precise integers via the bohrian model. I'm just stating that there is some kind of correlation, and perhaps there are things that can be learned from atoms about the universe as a whole, and vice versa.

 

[Drakkith]

Ah. Black holes. As far as we know their gravitational pull isn't from a huge amount of mass?

Perhaps I didn't word it right. The amount of gravity per "unit" of mass is always the same. Black holes are most definitely caused by massive amounts of mass.

So you're saying that energy via nuclear fusion is useless? Harnessing the heat of 100 Million degrees centigrade is nothing to be laughed at. We wouldn't need fossil fuels at all.

I was talking about Fusion due to gravitational confinement. Not magnetic or inertial or any other man made way.

Ok :) What I mean by everything with gravity having constant motion is that all planetary bodies spin, or turn, or whatever. The same, supposedly, is true for black holes but on a much more extreme level.

Sure, but that isn't the cause of gravity nor does it have an effect on it.

I understand Schrödinger's equation, energy levels of electrons and orbits of precise integers via the bohrian model. I'm just stating that there is some kind of correlation, and perhaps there are things that can be learned from atoms about the universe as a whole, and vice versa.

Alright.

 

[Searching]

I'm not sure how the statement "space is matter/energy" makes sense. Space is what contains matter/energy. It's some kind of dynamical background everything takes place on. If space actually was something, you could ask even further: What contains space?

We know space-time exists. We can observes its physical effects on planets and moons. Are you suggesting that something exists and effects the things around it, but is made of nothing? To me, that is what doesn't make sense.

As far as your question: What contains space? I don't know. The question in my mind is more along the lines of what exists beyond the point that space-time has expanded to. I don't know that either.

 

[Debt]

Alright, because gravity doesn't always fit into a 3d sphere of motion, mainly it works with a fixed orbit. Is it probable that its realitive to our limited observations, and lack of a unified answer. I know I am out of my league, but the cause of gravity, leads to effects of energy on other bodies, right? So could the opposing effects, work as a second opposing force. Yes I know I am talking about the weaker force. I am tring to say, could a black hole open our eyes on how we observe atomic forces. Relatively speaking.

 

[WannabeNewton]

Ah. Black holes. As far as we know their gravitational pull isn't from a huge amount of mass?

Non - rotating black holes are like any other massive object as long as you don't go past r = 2m. The gravitational field outside such a black hole depends on its mass just like any other object.There is only a problem if you tread past r = 2m.

 

[maverick_starstrider]

Ah. Black holes. As far as we know their gravitational pull isn't from a huge amount of mass?



So you're saying that energy via nuclear fusion is useless? Harnessing the heat of 100 Million degrees centigrade is nothing to be laughed at. We wouldn't need fossil fuels at all.



Ok :) What I mean by everything with gravity having constant motion is that all planetary bodies spin, or turn, or whatever. The same, supposedly, is true for black holes but on a much more extreme level.



I understand Schrödinger's equation, energy levels of electrons and orbits of precise integers via the bohrian model. I'm just stating that there is some kind of correlation, and perhaps there are things that can be learned from atoms about the universe as a whole, and vice versa.

The laws of gravity do not change anywhere. The rules for the effect of X amount of mass never change, on the moon there's just a lot less stuff (X is smaller). Just like Coulomb's law doesn't change if you have two electrons versus one, you just now have double the charge. Black holes are not an exception, they were once stars that collapsed in on themselves (due to gravity) after they exhausted their ability to undergo fusion. Stars are in a sort of equilibrium, their massive mass results in a constant gravitational "force" trying to collapse the star, but the absurdly high pressures cause hydrogen atoms to fuse to make helium, helium atoms to fuse to make beryllium and so on. These nuclear fusions release enormous amounts of energy that try to push outwards, this balance of gravitational collapse versus fusion is what gives a star its stability. As the core gets denser (i.e. as most of the hydrogen has fused to make helium, helium to make beryllium, etc.) the gravitational collapse will start to win the battle. Then one of two things happen, if the star is relatively small it will become a super dense compact star; such as a black hole, if it is large it will likely supernova.

I would also like to re-iterate what has been said many time already: The "orbit" of electrons "around" and atom (I use quotes because it is neither orbiting nor moving in time) is NOTHING like how a moon, say, orbits a planet. There's really nothing for it. Those images on like the cut-away CGI animations between scenes of the Big Bang Theory and such (you know http://www.epa.gov/radiation/images/atom.jpg these sorts of images) are simply completely wrong. That does not represent the behaviour of atoms in the slightest. Electrons have no set position, their position does not change in time, their angular momentum is quantized, etc. NOTHING LIKE PLANETARY ORBIT.

 

[Polyrhythmic]

We know space-time exists. We can observes its physical effects on planets and moons. Are you suggesting that something exists and effects the things around it, but is made of nothing? To me, that is what doesn't make sense.

As far as your question: What contains space? I don't know. The question in my mind is more along the lines of what exists beyond the point that space-time has expanded to. I don't know that either.

That's what I'm suggesting. There is nothing outside of what we call spacetime, and we have no reason to assume that spacetime behaves analoguous to anything we could actually imagine. Whether that mates sense to us or not is another question, but if this description successfully accounts for our measurement, it should be considered a valid.

 

[Drakkith]

Alright, because gravity doesn't always fit into a 3d sphere of motion, mainly it works with a fixed orbit. Is it probable that its realitive to our limited observations, and lack of a unified answer.

What? Gravity works everywhere.

I know I am out of my league, but the cause of gravity, leads to effects of energy on other bodies, right? So could the opposing effects, work as a second opposing force. Yes I know I am talking about the weaker force. I am tring to say, could a black hole open our eyes on how we observe atomic forces. Relatively speaking.

None of this makes any sense. What do you mean by a second opposing force? What is it opposing? What was the first one? As for the black hole affecting our view of atomic forces, it would only show us the effects of extreme gravity on an atom. Our current views would be unchanged.

 

[Polyrhythmic]

Alright, because gravity doesn't always fit into a 3d sphere of motion, mainly it works with a fixed orbit. Is it probable that its realitive to our limited observations, and lack of a unified answer. I know I am out of my league, but the cause of gravity, leads to effects of energy on other bodies, right? So could the opposing effects, work as a second opposing force. Yes I know I am talking about the weaker force. I am tring to say, could a black hole open our eyes on how we observe atomic forces. Relatively speaking.

"3d sphere of motion"? What is that supposed to mean?

 

[Debt]

3d sphere. I mean to say, In atoms the motion of electrons produces what i believe a bubble of matter. when i think of space-time gravity theroy, i can only see planets rolling around a drain, a 2d flat space. Am I way off base, thinking that way about gravity, or is it more of a 3d bubble solar system.

 

[Drakkith]

3d sphere. I mean to say, the motion of electrons produces, what i believe a bubble of matter, limited to its charge. when i think of space-time gravity theroy, i can only see planets rolling around a drain, a 2d flat space. besides the drain of course. Am I way off base, thinking that way, or is it more 3d, bubble solar system.

Space is 3d and Spacetime is 4d. The analogy of spacetime like a flat grid that mass deforms is simply that, an analogy. My personal view is of 4 of those grids surrounding an object with the grids curving inward toward the object. The more massive it is, the more curving gets done.

 

[Debt]

What? Gravity works everywhere.



None of this makes any sense. What do you mean by a second opposing force? What is it opposing? What was the first one? As for the black hole affecting our view of atomic forces, it would only show us the effects of extreme gravity on an atom. Our current views would be unchanged.

Gravity is the first force, I am asking if a second force that acts opposing gravity. I'm sure I'm just rusty.

 

[Polyrhythmic]

3d sphere. I mean to say, In atoms the motion of electrons produces what i believe a bubble of matter. when i think of space-time gravity theroy, i can only see planets rolling around a drain, a 2d flat space. Am I way off base, thinking that way about gravity, or is it more of a 3d bubble solar system.

If you are talking about this picture: http://upload.wikimedia.org/wikipedia/commons/archive/2/22/20101217174549!Spacetime_curvature.png" , you should disregard it, that's not the way gravity works.

 

[Debt]

ty That is helpfull.

 

[Drakkith]

Gravity is the first force, I am asking if a second force that acts opposing gravity. I'm sure I'm just rusty.

Are you asking if there is another force other than the 4 fundamental forces?

 

[danR]

GR states that there is no acceleration due to any "Force" when a particle in free fall enters the presence of a mass; particles in free fall simply start following the geodesics of the curved geometry due to whatever mass - energy distribution is causing the curvature. The equation of geodesic deviation is what quantifies "force" or acceleration in the sense that it gives deviations from this kind of free fall due to the presence of tidal gravitaitonal forces and one can add other forces to the equation.

Sorry to go back in this post, but:

This nicely puts what has been a problem for me: we've imbedded motion in a static 4-space geometry. Why should particles 'simply start following' the geodesics...? What does 'following' mean? Is it simply a description of the necessary direction of entropy? But isn't entropy in this case is driven by the influence of a gravitational 'force'? What is 'forcing' the system? I seem to come back to some kind of 'force'.

Let me illustrate: We place two masses in space, one a ball and the other a torus and insure they are stationary with respect to each other. Why do they follow the geodesic toward each other? Why not away? Or better, why should they move at all?

We know they are going to move together, the ball passing through the torus and we wind up with an oscillating system, losing energy in gravity-waves. But what kick-starts the whole thing? What gets the ball rolling?

 

[WannabeNewton]

Sorry to go back in this post, but:

This nicely puts what has been a problem for me: we've imbedded motion in a static 4-space geometry. Why should particles 'simply start following' the geodesics...? What does 'following' mean? Is it simply a description of the necessary direction of entropy? But isn't entropy in this case is driven by the influence of a gravitational 'force'? What is 'forcing' the system? I seem to come back to some kind of 'force'.

Well geodesic are curves of extremal length. One can derive the geodesic equation by applying the principle of stationary action so particles following geodesics are particles following extremal curves. All particles in classical mechanics seem to obey this principle (analogous to the statement that objects in free fall in flat space follow straight lines) as long as they are in free fall and I don't think we actually know WHY its just the way things are.

 

[danR]

Well geodesic are curves of extremal length. One can derive the geodesic equation by applying the principle of stationary action so particles following geodesics are particles following extremal curves. All particles in classical mechanics seem to obey this principle (analogous to the statement that objects in free fall in flat space follow straight lines) as long as they are in free fall and I don't think we actually know WHY its just the way things are.

I have a vague conjecture (I only have conjectures, and they are all vague anyway) as to why, but I'll start a new post on it, and not interrupt this one.

 

[Mitch Rowe]

Hi everyone..
Ive been thinking about "Gravity" for a while now and I would like to know if anyone thinks I am on the right track or not. Thanks to all who can help in advance.

First I have a question:

If one were to create a rotating spaceship in order to create a sort of "Artificial Gravity" to approximate Earths(Or any strength) "Gravity" then how would Matter react? I mean to say something like: If the air were removed from the spaceship would a hammer and a feather fall at the same rate? Would Matter follow all the rules of gravity(From thhe point of view of the Man standing on the inside edge of the spaceship dropping the hammer and feather) in the spaceship the same as on Earth??

Can I say that from the point of view of the Man in the spaceship that "Gravity" and "Centrifical Force" are the same??

 

[danR]

Hi everyone..
Ive been thinking about "Gravity" for a while now and I would like to know if anyone thinks I am on the right track or not. Thanks to all who can help in advance.

First I have a question:

If one were to create a rotating spaceship in order to create a sort of "Artificial Gravity" to approximate Earths(Or any strength) "Gravity" then how would Matter react? I mean to say something like: If the air were removed from the spaceship would a hammer and a feather fall at the same rate? Would Matter follow all the rules of gravity(From thhe point of view of the Man standing on the inside edge of the spaceship dropping the hammer and feather) in the spaceship the same as on Earth??

Can I say that from the point of view of the Man in the spaceship that "Gravity" and "Centrifical Force" are the same??

Only in the special case of an infinitesimal drop, and selecting the same 'vertical' line from centre to perimeter. As either falls, it will veer from centre and bang obliquely into your instrument panel, since the perimeter is moving much faster than the initial sideways motion of the object.

If they are 'dropped' side-by-side, they will 'fall' at the same rate, but divergently. On Earth they will fall convergently toward the centre of the earth. Hence, only choosing the same vertical line for each. You have to run the experiment separately for each.

So gravity and centrifugal 'force' are rather crappily similar. As long as everything stays put, and is all piled up at the same place, are they the same.

 

[Drakkith]

Let me illustrate: We place two masses in space, one a ball and the other a torus and insure they are stationary with respect to each other. Why do they follow the geodesic toward each other? Why not away? Or better, why should they move at all?

We know they are going to move together, the ball passing through the torus and we wind up with an oscillating system, losing energy in gravity-waves. But what kick-starts the whole thing? What gets the ball rolling?

If my rudimentary understanding of GR is correct, it is because the ball and the torus are moving through spacetime. The curvature of spacetime by mass causes the ball and torus to move closer to each other. There was nothing needed to get it all started because they were already moving.

 

[maverick_starstrider]

If you are talking about this picture: http://upload.wikimedia.org/wikipedia/commons/archive/2/22/20101217174549!Spacetime_curvature.png" , you should disregard it, that's not the way gravity works.

Basically the entire sentiment is awesomely summed up here: http://www.xkcd.com/895/ that comic had me laughing so hard.