Gravity verses electromagnetic attraction

[pulsar28]

We`ve seen how particles in zero gravity form clumps through electro magnetic attraction, and that these clumps will then develop gravitational forces. Isn`t then gravity merely the same as this electro magnetic attraction only on a larger scale?

 

[lzkelley]

Although many if not most hold onto the hope that some time (most likely long from now) all of the fundamental forces will somehow be unified... according to our understanding, gravity and E&M are very different.
For instance, E&M forces don't act on things without charge (i.e. neutral sums of charged particles or neutrinos(?) ).
Similarly, gravity doesn't effect massless particles (i.e. photons).
The details of the differences aren't too important, but another one of the main things, is that gravity is about a billion times weaker than the E&M forces.

 

[malawi_glenn]

Gravity does indeed affect massless particles, see 'gravitational red shift' etc.

 

[Nabeshin]

Also, gravity is strictly an attractive force, whereas electromagnetism can work to attract or repel.

 

[malawi_glenn]

electromagnetism can be "sheilded", gravity can not, since there is no such things as "negative" mass

 

[lzkelley]

Gravity does indeed affect massless particles, see 'gravitational red shift' etc.

You are absolutely correct that the presence of gravity does change the observational nature of massless particles; but at the same time i think its worth noting that its not gravity that is causing such a change (for instance redshift) - but the bending of space due to gravitational fields (to my knowledge)... this is really semantics - but i think it does illustrate an important conceptual different.

 

[NerfMonkey]

Also, gravity is strictly an attractive force, whereas electromagnetism can work to attract or repel.

In some cases gravity can be repulsive instead of attractive. But in every day circumstances you're right.

 

[Wallace]

You are absolutely correct that the presence of gravity does change the observational nature of massless particles; but at the same time i think its worth noting that its not gravity that is causing such a change (for instance redshift) - but the bending of space due to gravitational fields (to my knowledge)... this is really semantics - but i think it does illustrate an important conceptual different.

The 'bending of space' is simply a qualitative description of how gravity effects the motion of particles. It is not something different from gravity, it is gravity, if it is anything.

 

[Nabeshin]

In some cases gravity can be repulsive instead of attractive. But in every day circumstances you're right.

Elaborate. I am mystified.

 

[malawi_glenn]

You are absolutely correct that the presence of gravity does change the observational nature of massless particles; but at the same time i think its worth noting that its not gravity that is causing such a change (for instance redshift) - but the bending of space due to gravitational fields (to my knowledge)... this is really semantics - but i think it does illustrate an important conceptual different.

Gravity IS bending of space, according to the theories of Einstein

 

[W3pcq]

Maybe it is like the difference between a wave and a current in water in a way?

 

[malawi_glenn]

Maybe it is like the difference between a wave and a current in water in a way?

The theory of both EM and gravity is well known, and it is nothing like what you are trying to ascribe.

 

[W3pcq]

What I was trying to say is that maybe they are both different types of the same thing. By the way, what is "the theory of both EM and Gravity"? It is my impression that science still does not know exactly what EM is, or what the cause of gravity is. We know how to measure it and make predictions, but linking them would require a better understanding of what they are.

 

[malawi_glenn]

Ooop I should have written the "theories" ;-)
Unification of EM and Gravity is not done yet.

And please, specify: What are you referring to in your posts?

"Maybe it is ... " (What is 'it' referring to?)
"... that maybe they are both ... (What is 'they' referring to?)

 

[W3pcq]

Gravity, and EM is what I am referring to. If they can be unified, they must be linked somehow. The same way E=mc2, maybe gravity and em are phenomena of the same fundamentals. Comparing EM to a current, and G to a wave is to me an interesting way of looking at it because EM is a current of photons yet gravity is not a current of particles but instead it is a change in the structure of space just as a wave is not a current but instead it is a change in the structure, or a curvature of the ocean.

 

[malawi_glenn]

Have you done "Classic Electrodynamics" in collage / university yet? I am referring to "because EM is a current of photons "

unifying all physical theories into one, has always been a goal. String Theories are the candidates for this task today, even though their reasoning are quite a bit more intricate than yours.

 

[W3pcq]

Even if they come up with the right series of 1's or whatever they are trying to do, what will they understand after the math works?

 

[malawi_glenn]

How to unify Gravity with Quantum field theories.

 

[W3pcq]

Even if they do that, there will still be room for interpretation of what it all means. They will be able to do a whole new level of predictions which will allow huge advances in science which is totally awesome. That doesn't mean that no one can wonder what the findings mean philosophically.

 

[nuby]

Has it been proven or shown how mass creates a gravitation field? Where does the "gravity" come from within an atom? Do neutrons have something to do with gravity?

 

[malawi_glenn]

W3pcq: I concern physics. The OP asked a physics related question and he should get the answer from contemporary physics, not just speculations from laymen non-physicists (see the forum rules), they you may keep to yourself or post elsewhere.


nuby: All mass generates gravity, just not the neutron.

 

[nuby]

Everyone knows mass generates gravity. But how can mass do it?

 

[malawi_glenn]

I answered your question "has neutrons anything to do with mass".

Well a simple answer would be: Mass bends space-time, which is gravity (bending in space time).

 

[Redbelly98]

In some cases gravity can be repulsive instead of attractive. But in every day circumstances you're right.

I'll repeat Nabeshin's request for an explanation here.

 

[Nabeshin]

Lol thank you redbelly. That claim was thrown out there but nobody wants to take up the task of explaining it? :P

 

[W3pcq]

W3pcq: I concern physics. The OP asked a physics related question and he should get the answer from contemporary physics, not just speculations from laymen non-physicists (see the forum rules), they you may keep to yourself or post elsewhere.


nuby: All mass generates gravity, just not the neutron.

I may be mistaken, but I have always thought that a neutron generates gravity.

 

[malawi_glenn]

I may be mistaken, but I have always thought that a neutron generates gravity.

All mass generates gravuty, just not the neutron.

 

[W3pcq]

So the neutron doesn't generate gravity?

 

[malawi_glenn]

Lol thank you redbelly. That claim was thrown out there but nobody wants to take up the task of explaining it? :P

One can just google "Gravity + repulsive" and see if one gets realible source which can explian it. I did not find much, nor in my cosmology books.

 

[malawi_glenn]

So the neutron doesn't generate gravity?

Well what is the mass of the neutron?

 

[W3pcq]

Isn't the mass of the neutron=to the mass of a proton?

 

[malawi_glenn]

Isn't the mass of the neutron=to the mass of a proton?

Well roughly, it is a little little bit heavier. So does neutrons generate gravity?

 

[W3pcq]

I guess the answer you are looking for is no because gravity is a result of a change of the structure of space time and not generated by mass.

 

[malawi_glenn]

I tohugh you could use your logic, since I have two times stated that all mass generates gravity and since the neutrons have mass, they generate gravity. Many people thinks that the role of the neutron in atoms are to generate gravity, that is a very big missconception! (does not the hydrogen atom generate gravity??).

Another missconception is that people tends to separate gravity from space-time curvaturing. Gravity IS curvature in space, generated by mass.

 

[W3pcq]

I tohugh you could use your logic, since I have two times stated that all mass generates gravity and since the neutrons have mass, they generate gravity. Many people thinks that the role of the neutron in atoms are to generate gravity, that is a very big missconception! (does not the hydrogen atom generate gravity??).

Another missconception is that people tends to separate gravity from space-time curvaturing. Gravity IS curvature in space, generated by mass.

According to general relativity it is. Of coarse that is a grossly over simplified way of putting it.

 

[malawi_glenn]

What is over simplified? The General Theory of gravity? Have you studied it at university?

 

[W3pcq]

What is over simplified? The General Theory of gravity? Have you studied it at university?

That gravity is caused by the curved space time. Do you actually understand what that means or how that works?

Also, I have never heard of "The general theory of gravity", what is that?

 

[W3pcq]

I tohugh you could use your logic, since I have two times stated that all mass generates gravity and since the neutrons have mass, they generate gravity. Many people thinks that the role of the neutron in atoms are to generate gravity, that is a very big missconception! (does not the hydrogen atom generate gravity??).

Another missconception is that people tends to separate gravity from space-time curvaturing. Gravity IS curvature in space, generated by mass.

Sorry, you should have said it different, you must not know the english language very well. You should have said it like this: All mass generates gravity, NOT just the neutron.

 

[W3pcq]

It is just boring to thoughtlessly recite lines that you have memorized and not even understand what you are saying.

 

[cristo]

That gravity is caused by the curved space time. Do you actually understand what that means or how that works?

I'm not sure that this is the place for teaching you General Relativity. In short, and as malawi_glenn has mentioned, gravity is the curvature of spacetime-- it is not cause by the curvature of spacetime.

In some cases gravity can be repulsive instead of attractive. But in every day circumstances you're right.

Elaborate. I am mystified.

I guess Nerfmonkey is talking about exotic scenarios in which the pressure of the "matter" is negative, like in the case of "dark energy" (whatever that may be). This will give rise to a repulsive gravity term.

 

[W3pcq]

One theory about the accelerating universe is that gravity becomes repulsive in some conditions.

 

[cristo]

One theory about the accelerating universe is that gravity becomes repulsive in some conditions.

You mean like the condition I just mentioned?

 

[malawi_glenn]

i. Yes a know a bit how Einsteins field equations work, but I will not be able to study its derivations and so on until I get into grad-school, I am still undergraduate and we have still only got the forumulas and learn how to use them, not to derive them.

ii. The general theory of gravity is called many things, like Einsteins general theory of relativity and so forth.

If you don't have any idea what this is, then I am stunned how you still want to argue with me about what gravity is and how it works. The language of physics is math, therefore one can not understand physics correct by using every day life thinking and non-mathematical reasoning.

iii. I ve seen many people who have the missconception that the neutron is the only source of gravity in atoms.

iv. I have quite good knowledge about the English language, if I say "All mass generates gravity" then I of course mean that neutrons, which has mass, is generating gravity. Then one can use his/hers logic to draw the conclusion that massive objects which are not neutrons also generates gravity.

v. I think its boring that people who aren't students of physics, or working physicists, can judge wheater a person have understand something or not. As cristo said, this is not the appropiate place where to study general theory of gravity (I can give you a study plan and book references if you want to learn it, or recommend a college/university), but we (who are physicists) can answer questions about gravity in a short and quite understandable way (that is of course something subjective).

The main question was "what is the difference between gravity and electro magnetic force"? Then some missconceptions where brougth up (the ones I mentioned earlier), and those I gave short comments on.

 

[W3pcq]

I would like to know more about the link between time and gravity. When an object approaches a gravitational field, it's clock slows right. Why is this? Does this have anything to do with sub atomic spin?

 

[W3pcq]

You mean like the condition I just mentioned?

You added that part in after I posted.

 

[W3pcq]

i. Yes a know a bit how Einsteins field equations work, but I will not be able to study its derivations and so on until I get into grad-school, I am still undergraduate and we have still only got the forumulas and learn how to use them, not to derive them.

ii. The general theory of gravity is called many things, like Einsteins general theory of relativity and so forth.

If you don't have any idea what this is, then I am stunned how you still want to argue with me about what gravity is and how it works. The language of physics is math, therefore one can not understand physics correct by using every day life thinking and non-mathematical reasoning.

iii. I ve seen many people who have the missconception that the neutron is the only source of gravity in atoms.

iv. I have quite good knowledge about the English language, if I say "All mass generates gravity" then I of course mean that neutrons, which has mass, is generating gravity. Then one can use his/hers logic to draw the conclusion that massive objects which are not neutrons also generates gravity.

v. I think its boring that people who aren't students of physics, or working physicists, can judge wheater a person have understand something or not. As cristo said, this is not the appropiate place where to study general theory of gravity (I can give you a study plan and book references if you want to learn it, or recommend a college/university), but we (who are physicists) can answer questions about gravity in a short and quite understandable way (that is of course something subjective).

The main question was "what is the difference between gravity and electro magnetic force"? Then some missconceptions where brougth up (the ones I mentioned earlier), and those I gave short comments on.

I didn't ever mean to get into an argument with you. You kept wording a sentence wrong making it mean something that you didn't intend.

 

[W3pcq]

Look, I'm sorry I used a metaphor that isn't in a physics book to try and look at things from a new angle. Why are you guys so upset about it?

 

[malawi_glenn]

I would like to know more about the link between time and gravity. When an object approaches a gravitational field, it's clock slows right. Why is this? Does this have anything to do with sub atomic spin?

Remember that the general theory of gravity is not a quantum theory.

You may want to start a new thread or search for old or just google, there is plenty much written about this topic.

 

[malawi_glenn]

I didn't ever mean to get into an argument with you. You kept wording a sentence wrong making it mean something that you didn't intend.

So what is wrong with "All mass generates gravity" ?

 

[W3pcq]

Remember that the general theory of gravity is not a quantum theory.

You may want to start a new thread or search for old or just google, there is plenty much written about this topic.

This is an Astrophysics forum not a GR forum. If we can only talk about GR, then maybe it should be moved there?