Is Gravity Really a Fundamental Force?

[EarthlingX]

Well, if it's Hydrogen plasma, it's made up of an equal amount of electrons and protons, so the net charge is zero

Damn, i was happy whole 10 min

Is there such a thing as proton plasma ?

 

[csmyth3025]

I encountered these statements on this Wikipedia page:

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

The one thing is that that wouldn't be a kilogram of protons - that would be enough protons to make 1 C of charge (which is something like 10^-8 kg of protons)...

Hmm... I think I need to study units of electrical charge a bit more and delve a little more deeply into the Reissner–Nordström metric - at least to the extent that I can grasp the concept. This is a very interesting subject.

Chris

 

[MeteorWayne]

Well, if it's Hydrogen plasma, it's made up of an equal amount of electrons and protons, so the net charge is zero

Damn, i was happy whole 10 min

Is there such a thing as proton plasma ?

There could be, but it would not be hydrogen plasma, which is the question you asked....

 

[ramparts]

I encountered these statements on this Wikipedia page:

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

The one thing is that that wouldn't be a kilogram of protons - that would be enough protons to make 1 C of charge (which is something like 10^-8 kg of protons)...

Hmm... I think I need to study units of electrical charge a bit more and delve a little more deeply into the Reissner–Nordström metric - at least to the extent that I can grasp the concept. This is a very interesting subject.

Chris

Charge is a fundamental property of an object, just like mass is. The two are pretty analogous - in fact, Coulomb's law for the electric force has the exact same form as Newton's law for gravity, just replace the two masses with two charges. The force of gravity between two objects is equal to a constant times the product of their masses divided by the square of their distance. The electric force between two objects is equal to a constant times the product of their charges divided (again) by the square of their distance.

 

[csmyth3025]

by ramparts » Sun Aug 23, 2009 10:03 pm

The force of gravity between two objects is equal to a constant times the product of their masses divided by the square of their distance. The electric force between two objects is equal to a constant times the product of their charges divided (again) by the square of their distance.

Of course the difference is that electrical force can be either attractive or repulsive whereas gravity - as far as we know at this point is only attractive (no anthropomorphism intended). [this is the first chance I've had to use that word - I can't wait to get to the "B" section of the dictionary]

In terms of repulsive force, I take it that proton for proton the repulsive force of their charge is 10^36 times as great as the attractive force of their mutual gravitation at any given distance. I'm not sure how that works out for electrons since their mass is, I believe, 1/1836 that of a proton but they still carry the same unit charge as a proton (only opposite).

My mind wanders back to that funny experiment I discussed several posts back. If you pump enough protons into a black hole, is it possible that it would just "blow up" - spewing all the matter and energy inside all over the place in a humongous explosion? Or rather, as you explained earlier, would the event horizon simply disappear leaving a "naked singularity". I realize that a "naked singularity" is considered impossible (for reasons that I hope my on-going education will eventually reveal).

Chris

 

[j_rankin]

My currently believed theory of how gravity works goes like this:

In an area of space, there is an overall amount of space it can contain. The presence of matter means that a large amount of space is concentrated on one point, thus bending all other space around it to fill that concentration.

To try to make an analogy - Imagine the solar system was whole universe and thit had a limited amount of energy within it. If you removed the sun and replaced it with evenly spaced matter, the solar system would still have the same amount of energy in total, but the energy would not be concentrated in one point, and thus there would be no gravity. If you then put the Sun back in place, then the total energy of the solar system would once again not change, but it would be concentrated at the centre. Thus the existence of gravity.

If you imagine a knitted woollen cloth and put a small but very heavy weight in the middle of it, then the cloth would stretch and the gaps between each thread would increase as they got stretched by the heavy weight, but the overall amount of material in the cloth would not change. An ant crawling along the cloth would have a far easier time getting to the middle, and a far harder time crawling away from the middle.

 

[darkmatter4brains]

I think the only benefit of formulating E&M that way would be philosophical - it might be a point against the substantivalist position on GR.

You mean this field tensor? http://en.wikipedia.org/wiki/Electromagnetic_tensor The one that allows you to write Maxwell's equations in two equations (one, if you use the right gauge)? I'd imagine if there were a way to make that the dynamical variable in a GR-like theory it would be found, but then this tensor isn't the dynamical variable in E&M (unless I'm mistaken, the gauge potential is). Again, I don't know much of any QFT, but I'm pretty sure E&M doesn't come from quantizing that field, it comes from quantizing the vector potential.

Yes, that's the one. I didn't see it in that article, but you're correct. Using the potential, it can go down to one equation. If I remember right, it had the D'almbertian of the potential equal to the permeability of free space multiplied by the current 4-vector.

 

[darkmatter4brains]

The laws of physics can certainly be applied within an event horizon - it's just very near the singularity that things get fishy (i.e., on very small scales where quantum effects become important).

I always wondered about this. Like, how do we really know what's going on under the event horizon? What I mean is, a couple hundred years ago you could have predicted all sorts of stuff with the Newtonian theory and you'd be dead wrong, because the theory breaks down. But, sometimes when a theory breaks down, it doesn't really advertise it. It gives you an answer that looks very reasonable, that is, until observation tells you it's dead wrong, albeit in a very subtle way.

But that's the problem with GR, it makes predicitons within the event horizon, but we can't actually observe what's going on inside the event horizon to say for sure the theory is correct in there. We know it for sure breaks down close to the singularity, but is it breaking down in a more subtle way before that? Are there unkown processes/physics in there taking place we don't know about? Seems possible at least.

I'll admit too, I never liked the idea of a singularity. Actually, I don't like the idea of an infinitely small point of infinite density, whether it be the singularity at the center of a black hole, or the original state of the Universe at the beginning of the Big Bang theory, or something else. I really hope somebody discovers something soon that gets rid of these ideas (not the big bang theory! I like that, just not how it starts out!)

 

[ramparts]

by ramparts » Sun Aug 23, 2009 10:03 pm

The force of gravity between two objects is equal to a constant times the product of their masses divided by the square of their distance. The electric force between two objects is equal to a constant times the product of their charges divided (again) by the square of their distance.

Of course the difference is that electrical force can be either attractive or repulsive whereas gravity - as far as we know at this point is only attractive (no anthropomorphism intended). [this is the first chance I've had to use that word - I can't wait to get to the "B" section of the dictionary]

Well, that's one way of looking at it Me, I don't see it as being a difference between the forces, I see it as being a difference between charge and mass. They play analogous roles in both forces, but while mass can only be positive, charge can be negative or positive. Changing the sign of one changes the sign of the force, and the sign of the force is what determines whether it's attractive (negative) or repulsive (positive). If there were negative masses, they'd repel positive mass through gravity. But that's a bizarre concept :lol:

In terms of repulsive force, I take it that proton for proton the repulsive force of their charge is 10^36 times as great as the attractive force of their mutual gravitation at any given distance. I'm not sure how that works out for electrons since their mass is, I believe, 1/1836 that of a proton but they still carry the same unit charge as a proton (only opposite).

Since the mass doesn't factor into the electric force (remember, it's just a constant, the two charges, and the distance between them), there'd be the exact same force between electrons as between protons. Now, since the force is equal to the mass times acceleration (Newton's F=ma), then the electrons would accelerate more under the same force, since they're lighter.

My mind wanders back to that funny experiment I discussed several posts back. If you pump enough protons into a black hole, is it possible that it would just "blow up" - spewing all the matter and energy inside all over the place in a humongous explosion? Or rather, as you explained earlier, would the event horizon simply disappear leaving a "naked singularity". I realize that a "naked singularity" is considered impossible (for reasons that I hope my on-going education will eventually reveal).

Well, no. At least, not unless something very funny happens on a quantum level. A naked singularity is still a singularity, and once stuff is down there, you shouldn't be able to get it out

 

[ramparts]

The laws of physics can certainly be applied within an event horizon - it's just very near the singularity that things get fishy (i.e., on very small scales where quantum effects become important).

I always wondered about this. Like, how do we really know what's going on under the event horizon? What I mean is, a couple hundred years ago you could have predicted all sorts of stuff with the Newtonian theory and you'd be dead wrong, because the theory breaks down. But, sometimes when a theory breaks down, it doesn't really advertise it. It gives you an answer that looks very reasonable, that is, until observation tells you it's dead wrong, albeit in a very subtle way.

Well, we don't know, as we can't test inside the horizon. You're pretty right on - if the theory is so well-confirmed in places it can be tested, we can probably trust it inside the horizon too, but we'll never actually know. But while we know about plenty of the limitations of GR, we don't currently have any reason to expect it to break down specifically inside the horizon - there's really nothing special about spacetime there, it just happens to look funny from the outside.

 

[ramparts]

I think the only benefit of formulating E&M that way would be philosophical - it might be a point against the substantivalist position on GR.

You mean this field tensor? http://en.wikipedia.org/wiki/Electromagnetic_tensor The one that allows you to write Maxwell's equations in two equations (one, if you use the right gauge)? I'd imagine if there were a way to make that the dynamical variable in a GR-like theory it would be found, but then this tensor isn't the dynamical variable in E&M (unless I'm mistaken, the gauge potential is). Again, I don't know much of any QFT, but I'm pretty sure E&M doesn't come from quantizing that field, it comes from quantizing the vector potential.

Yes, that's the one. I didn't see it in that article, but you're correct. Using the potential, it can go down to one equation. If I remember right, it had the D'almbertian of the potential equal to the permeability of free space multiplied by the current 4-vector.

Ummm...let me think about this.... I think that's right, although I'm not sure if there's a constant before it. The constant is actually probably some power of c (it would make sense, no? As a combination of the electric and magnetic constants), so we'd set it to 1. Also, I think the current 4-vector is negative there. But yeah, that's the basic idea :lol:

 

[EarthlingX]

Please explain: is it possible we are misinterpreting cause and effect ? Do fields cause gravity or is a gravity just a common attribute with some angle/transformation of effect ?

 

[EarthlingX]

This is interesting reading, which leaves me with serious headache ... :roll:
(edit 28.8.2009, title of the article)
Pushing the envelope of general relativity
Horatiu Nastase, Global Edge Institute, Tokyo Institute of Technology, Tokyo, Japan
Published August 24, 2009 :
http://physics.aps.org/articles/v2/71

 

[centsworth_II]

Trying to avoid headaches, but still resolve my confusion....

Physicists know that temperature is simply an effect and not a separate force or particle. They are not looking for a "thermoton" or a "thermotonic field". Why is gravity not treated the same way: as an effect of matter/energy but not a separate force or particle in its own right?

 

[EarthlingX]

Oh, temperature is simple, it's just a vibration or at least i think so, but gravity is a little more tricky :lol:
They are all after very big particle no one can see, maybe after they finish LHC.
http://en.wikipedia.org/wiki/Higgs_boson

 

[centsworth_II]

Oh, temperature is simple, it's just a vibration....

So what if gravity is just as simple: Just a warping of space, as Einstein said, not a separate force, field, or particle.

 

[EarthlingX]

Oh, temperature is simple, it's just a vibration....

So what if gravity is just as simple: Just a warping of space, as Einstein said, not a separate force, field, or particle.

Could be, but claiming that can move you to unexplained :lol: Actually, that's what Higgs is in a way. Just a nasty big direction of force. Or am i wrong ?
Another thing is, i don't think we really now what 'space' is. Can we break it into particles ? We can compress it, but can we expand it ? (check antigravity thread in unexplained viewtopic.php?f=17&t=19513 for a most brilliant solution
Now imagine warped space and flat time, add other fields when they get big enough to notice. I would guess you would need at least one dimension per quark flavor, couple more for basic forces, and there you go, welcome to asylum :lol:

 

[centsworth_II]

So what if gravity is just as simple: Just a warping of space, as Einstein said....

Could be, but claiming that can move you to unexplained...

Wow. Einstein moved to "Unexplained". Now I really am confused.

 

[EarthlingX]

So what if gravity is just as simple: Just a warping of space, as Einstein said....

Could be, but claiming that can move you to unexplained...

Wow. Einstein moved to "Unexplained". Now I really am confused.

What is space ? Warping of space might be perceived effect not the cause.
Yea, i was a bit fast about that

 

[ramparts]

centsworth, here's one way to think of it:

On very small scales (we call them quantum scales), quantum mechanics takes over, and brings with it all the associated craziness. In particular, everything has to be quantized (hence the name quantum mechanics), meaning everything comes in discrete chunks. So to include gravity in the picture, we need to quantize spacetime. It can't be a smooth background, on a quantum scale. Quantizing gravity, of course, is the tricky part

 

[centsworth_II]

It seems to me that quantizing space and quantizing gravity are two different things. At least they are if you imagine quantized gravity as being a particle which moves in space as other fundamental particles do.

 

[EarthlingX]

It seems to me that quantizing space and quantizing gravity are two different things. At least they are if you imagine quantized gravity as being a particle which moves in space as other fundamental particles do.

There is a little problem with that. I think we don't have any evidence of gravity behaving like a wave. You know of any ?
I'm also unaware of any evidence of gravity particle interaction.

 

[ramparts]

Well, gravitational waves We expect them from GR, and there is pretty strong indirect evidence. Hopefully there will be more direct evidence very very soon.

 

[centsworth_II]

So if found, gravity waves would support the idea that gravity is a distortion of space due to the presence of matter/energy. Gravity waves would not indicate the presence of a gravity force or particle.

Maybe the real problem keeping us from a Theory of Everything is the nature of space, not the nature of gravity.

 

[dryson]

Is there a reason in current mainstream physics why gravity must exist as a separate force rather than just as an effect of mass/energy on space? Could it be that there are no gravitons, no gravity field? Could gravity just be an effect that the presence of mass/energy has on space as Einstein said?

The problem of what space is -- if it is quantized, for example -- would still remain, but not the problem of how to quantize gravity.

First off space cannot be affected upon nor can space affect upon any particle within space. There are two forms of space.
Geometric Space - Geometric Space is an area that particles occupy where a geometric shape has been drawn to better study the particles within the articially drawn shape.

Regular Space - Regular Space is an area outside the planetary bounds where particles freely move around in random fashion. When particles encounter each other an equal and opposite reaction will occur based upon the particles energetic properties and how these properties affect the other particle. Space is a medium, because space contains other particles like a fishbowl contains water. But unlike the fishbowl which can have a force of energetic exertion placed upon it space however cannot as space is the absolute of nothing or the inability of an equal and opposite reaction occuring based on particle collision taking place.

Gravity is an attractive force just as the attractive force of a piece of metal when an electrical current is ran though it, the metal then becomes either magnetic or paramagnetic in its attraction.

Gravity is not present throughout the Universe, Gravity is only produced by planets, suns and other spacial bodies that or solid and do not have an active core, are solid and have a semi-fluid core or active core. If gravity was present throughout the Universe then any smaller bodies such as micrometeors would be pulled into an orbit around clusters like nebulea's. But since this does not occur gravity is generated by the criteria above. Gravity is also like a magnet in so much that the field of influence will range as far as the the properties of the material having an electrical current ran through it.

If gravity is not based on magentism then why is a blocked pound of steel pulled faster to the Earth then a blocked piece of wood? We know that a current when ran through metal creates an electromagnetic affect and that opposite magnetic fields attract. So the steel block is having an electrical current ran through it based on Atmospheric electricity which causes the steel block to become more magnetised then it had been when stationary thus causing it to be pulled towards the stronger and opposite magnetic field of attraction.

The wood block will be pulled towards the Earth but not as fast as the steel block because of the amount of non-magentiseble material contained within the wood itself that can be affected upon by the electrical currents within the atmosphere.

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

The question though if gravity does exist in space and is everywhere then gravity would have to be a particle or the graviton which could then transfer it's energetic potential through a gravitational wavelength. If gravity a wavelength then it would have to be generated from a singular source such as the graviton or planet, sun or other collected group of particles that generate the gravitational field based off of the residual energy possibly lost due the interaction between two or more particles.

Another question would be what type of material would cause this residual amount of energy to increase its magnetic or electromagnetic affect on other particles? Is there some sort of metal or crystal that has been forged around the foundry of the planets core to increase this affect? All we know is what we have mined on the surface of the planet when it comes to understanding how magnetism and gravity works, which cannot be assumed to how the layers closer to the center of the Earth function and or operate.