gravity and nuclear forces

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j_rankin

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hello all,

I was just pondering about the correlation between gravity and the nuclear forces and i had a thought i'd like some of your thoughts about.

Everyone seems to think of gravity an an attraction between two objects, but if gravity is an energy wave, then surely there is much more gravity heading off into space than is used to attract objects. Thus my following hypothesis:

Could gravity and the nuclear forces be the same thing?

If the nuclear forces radiating out of an atom were stronger than the necessary energy needed to hold them together then would that energy, on an accumulative scale, be able to attract large objects?

Think of it on a cosmic scale:

The sun radiates enough gravity to keep the planets in orbit and the solar system in place, but there is far more gravity heading off out into space that isnt pulling on anything. By the time you have billions of stars (a galaxy) each of them having a tiny pull but still some kind of pull, then on an accumulative scale they are able to keep other galaxies in orbit around them. (and there is still far more gravitic energy heading off out into intergalactic space).

I suspect there is already physics which explains that this isn't the case but i would appreciate some thoughts on this.
 
M

MeteorWayne

Guest
Quick answer is, no not even close. The Strong and Weak nuclear forces, at short (i.e. nuclear) distances are hundreds oforders of magnitudes stronger than gravity.

And you are incorrect about your understanding about the gravity of the sun.

The gravity from the sun affects every other object in the Universe. The strength is less as you go further away, but it goes on forever. I don't know about the nuclear forces, I'm afraid I'll have to leave that to those with a better understanding of those forces.
 
J

j_rankin

Guest
I understand that the nuclear forces are orders of magnitude stronger than gravity, but if it was each atom pulling each atom, then by the time they got to the distances involved between planetary bodies, then those forces would be orders of magnitude weaker.

If every atom is pulling every other atom towards it, then even though the earth and moon have alot of distance between them, there is still alot more pulling energy heading off into space.
 
M

MeteorWayne

Guest
the strong and weak nuclear forces don't act at the distance between atoms, they are only relevant at distances within the nucleus of the atom.

Atoms interact mosrly through electromagnetic forces, and like gravity, they operate at all distances within the Universe.
 
J

j_rankin

Guest
consider this:

If you took a neutron star and placed it a mile away from another neutron star, they would smash together at an incredibly fast rate, with an incredible force. Probably enough of a force to create a gamma ray burst. I would consider that force to be enormous, perhaps as strong by scale as an atoms pull towards its subatomic particles (Some parts of the stars might even get blasted off at almost light speed).

If this happened on an atomic scale (a very heavy atom smashes into another very heavy atom at a very fast rate) we would also see a very violent reaction, but many orders of magnitude smaller than that of a gamma ray burst (Parts of the exploding atoms would also get blasted off at light speed).
 
J

j_rankin

Guest
I don't understand why it is that the nuclear forces only apply at subatomic distances. If it is the case that they only apply at subatomic distances then surely that must be because the force has decayed over distance much the same as gravity does. Thus my hypothesis that en masse the nuclear forces create gravity.
 
D

DrRocket

Guest
j_rankin":3jwchzxa said:
hello all,

I was just pondering about the correlation between gravity and the nuclear forces and i had a thought i'd like some of your thoughts about.

Everyone seems to think of gravity an an attraction between two objects, but if gravity is an energy wave, then surely there is much more gravity heading off into space than is used to attract objects. Thus my following hypothesis:

Could gravity and the nuclear forces be the same thing?

If the nuclear forces radiating out of an atom were stronger than the necessary energy needed to hold them together then would that energy, on an accumulative scale, be able to attract large objects?

Think of it on a cosmic scale:

The sun radiates enough gravity to keep the planets in orbit and the solar system in place, but there is far more gravity heading off out into space that isnt pulling on anything. By the time you have billions of stars (a galaxy) each of them having a tiny pull but still some kind of pull, then on an accumulative scale they are able to keep other galaxies in orbit around them. (and there is still far more gravitic energy heading off out into intergalactic space).

I suspect there is already physics which explains that this isn't the case but i would appreciate some thoughts on this.
There is far too much word salad here to permit a cogent line-by-line critique. But here is the general picture.

There are four known forces, gravity,the strong force, the weak force and electromagnetism We we have a quantum field theory, due to Weinberg, Salam and Glashow that explains the electromagnetic and weak forces as different aspects of a single force, the electroweak force. There is research going on to try to unify the electroweak force and the theory of the strong force (quantum chromodynamics) into a single "Grand Unified Theory" or GUT. No such theory currently exists. There is also research going one to unify the electro weak, strong and gravitational forces into a single "Theory of Everything" (TOE). Even if successful those theories must agree with existing descriptions of the four forces for most applications, where current theories are known to be quite accurate.

None of the potential as-yet-undiscovered theories are going to change the basic nature of any of the four forces in normal applications. Those theories are too accurate and too well supported by mountains of experimental data. So your reformulation of those theories just does not hold water.
 
D

DrRocket

Guest
j_rankin":21bksmsf said:
I don't understand why it is that the nuclear forces only apply at subatomic distances. If it is the case that they only apply at subatomic distances then surely that must be because the force has decayed over distance much the same as gravity does. Thus my hypothesis that en masse the nuclear forces create gravity.
They are short range forces.

The strong force, for instance, actually increases with distance, rather like stretching a rubber band. If you take 2 quarks bound by the strong force and pull them apart, then eventually you have enough potential energy in the deformed bond to create a new set of quark pairs -- the link breaks and you now have 2 pairs of quarks closely spaced rather that a single pair with a significant separation. Thus the strong force is self-limiting. IT is NOT like gravity and electromagnetism and it does NOT obey an inverse square law.

Both the strong and weak forces are mediated by the exchange of a massive boson, as opposed to the electromagnetic force which is mediated by the photon which has zero rest mass. Gravity is thought to be mediated by another particle of zero rest mass, a graviton, but there is no current viable theory of quantum gravity so the graviton is speculative. Massive particles are associated with short distance (in particular finite distance) forces, while forces mediated my particles of zero rest mass act over arbitrarily large distances (basically the inverse square Law.
 
A

ArcCentral

Guest
Could gravity and the nuclear forces be the same thing?
I don't think anyone in the business has that under consideration, but if you got a hunch, run with it and see what you can come up with. Chances are that 99.999% of what you think of, will be heading to the trash bin, but that .001% is always a joyous occasion, regardless of whether it accomplishes your goal.
 
D

DrRocket

Guest
ArcCentral":oqvkysj5 said:
Could gravity and the nuclear forces be the same thing?
I don't think anyone in the business has that under consideration, but if you got a hunch, run with it and see what you can come up with. Chances are that 99.999% of what you think of, will be heading to the trash bin, but that .001% is always a joyous occasion, regardless of whether it accomplishes your goal.
Actually many people in the business are extremely aware of the characteristics of all four known forces -- electromagnetic, strong, weak, gravitational. They are aware of the similarities and differences. The strong, weak, and electromagnetic forces are carried by known bosons, while the gravitational force is only conjectured to be carried by an undiscovered boson, the graviton. The bosons that carry the strong and weak forces have non-zero rest mass, while the boson that carries the electromagnetic force, the photon has zero rest mass. The graviton, if it exists is thought to also have zero rest mass. It is the lack of rest mass of the boson for the electromagnetic force and the hypothesized boson for gravity that explains why those forces obey an inverse square law and have unlimited range, while the strong and weak forces are limited.

It is also a subject of intense research to develop a unified theory that explains all of the known forces, presumably in a framework that unifies them and shows them to be different aspects of a single theory that manifests the forces as we know them at modest energies but shows a unification at extremely high energies.


The problem of unifying the known forces at high energies has proved to be a daunting task, and at this time there is no known unifying theory or indeed any viable quantum theory of gravity. Gravity has defied all attempts to devise a renormalizable theory, apparently because of self-interaction of the graviton with itself. This problem has occupied and defied some of the most brilliant and creative minds on the planet. and involves some extremely complex mathematics and in fact has and continues to require the development of entirely new mathematical theories. It is quite probably the deepest and most difficult research program in theoretical physics.

Your suggestion that an amateur,lacking all knowledge of the underlying physics of quantum field theory has even a .001% chance of cracking this difficult problem is simply absurd. It demonstrates a complete lack of appreciation for the issues involved and will likely lead to a great deal of frustration on the part of anyone sufficiently naive to attack it without any of the necessary tools. The only reasonable way to attack this problem is to first understand what is known and then and only then attempt to devise better theories. To advise anyone to do otherwise is pointless and demonstrates lack of recognition of the frustration that that can be inflicted through a recommendation made in total ignorance.

As usual, you don't know what you are talking about, have no idea of the underlying physics, are making a foolish and potentially destructive suggestion, and apparently have paid no attention to the posts in this thread that precede yours..
 
L

lukman

Guest
Is it heat or gravity creates fusion? if both, which is the key role here? if it was gravity, then we can imitate it using centrifugal force, like the one in astronaut g force training, can we fuse hidrogen that way? how many g force needed?
 
Y

yevaud

Guest
lukman":3iqei14n said:
Is it heat or gravity creates fusion?
You might remember it's "Thermo-nuclear." The "Therm" should tell you something.
 
D

drwayne

Guest
I started to say "Pressure and Temperature" - of course the two are somewhat related. ;)

Wayne
 
J

j_rankin

Guest
Thanks DrRocket, your responses have helped me to understand an awful lot. I won't stop thinking about big theories though as i love spending hours thinking.
Whenever i get stumped, you're often there to make me realise.

I know I don't understand anywhere near as much as millions of minds who have been before me, but if it wasn't for my trying i would have no motivation to have any interest in this field of physics.
 
D

DrRocket

Guest
lukman":3qd72lnk said:
Is it heat or gravity creates fusion? if both, which is the key role here? if it was gravity, then we can imitate it using centrifugal force, like the one in astronaut g force training, can we fuse hidrogen that way? how many g force needed?
It is basically getting enough energy to cause the nucleii to get close enough together for the strong force to overcome the repulsion of the positively charged nucleii. That is usually accomplished by having the nuclei traveling really fast (temperature).

To force nucleii together with gravity takes a LOT of gravity. If you had enough centrifugal force in the centrifuge for astronaut training you would wind up with REALLY flat astronauts (the Maryland experiment that drwayne linked is trying to confine plasma in a centrifuge not directly cause fusion, and reemember that plasmas are hot).
 
D

drwayne

Guest
j_rankin":28vq07ct said:
Thanks DrRocket, your responses have helped me to understand an awful lot. I won't stop thinking about big theories though as i love spending hours thinking.
Whenever i get stumped, you're often there to make me realise.

I know I don't understand anywhere near as much as millions of minds who have been before me, but if it wasn't for my trying i would have no motivation to have any interest in this field of physics.
Keep trying, thinking and reading.

:)
 
D

drwayne

Guest
DrRocket":3n8h99zj said:
lukman":3n8h99zj said:
Is it heat or gravity creates fusion? if both, which is the key role here? if it was gravity, then we can imitate it using centrifugal force, like the one in astronaut g force training, can we fuse hidrogen that way? how many g force needed?
It is basically getting enough energy to cause the nucleii to get close enough together for the strong force to overcome the repulsion of the positively charged nucleii. That is usually accomplished by having the nuclei traveling really fast (temperature).

To force nucleii together with gravity takes a LOT of gravity. If you had enough centrifugal force in the centrifuge for astronaut training you would wind up with REALLY flat astronauts (the Maryland experiment that drwayne linked is trying to confine plasma in a centrifuge not directly cause fusion, and reemember that plasmas are hot).
That is why I referred to the Maryland experiment as tangentially related - the tangent pun was just a bonus. :)

The first link I posted has a pretty good discussion of how hard one would have to spin things, and how
unobtanium would have to be used in the construction.
 
D

DrRocket

Guest
drwayne":2in26lvw said:
j_rankin":2in26lvw said:
Thanks DrRocket, your responses have helped me to understand an awful lot. I won't stop thinking about big theories though as i love spending hours thinking.
Whenever i get stumped, you're often there to make me realise.

I know I don't understand anywhere near as much as millions of minds who have been before me, but if it wasn't for my trying i would have no motivation to have any interest in this field of physics.
Keep trying, thinking and reading.

:)
Heavy on the reading and thinking until you have a firm foundation, then creativity can be profitable.
 
D

drwayne

Guest
Good point:

Too many people trot out the Einstein quote about imagination and knowledge, and
take it to mean that "All you need is imagination, you don't need any knowledge.
Learning the basics is a waste of time"

Wayne

.p.s. Reading "popular" level science books can provide valuable context and
can stoke your interest, but they can only take you so far. Reading 100
popular level books does not, as some seem to believe, equvalent to
a degree, or does it make you much more than a cocktail party expert.
Stretch and get some good textbooks.
 
D

DrRocket

Guest
drwayne":319np214 said:
Good point:

Too many people trot out the Einstein quote about imagination and knowledge, and
take it to mean that "All you need is imagination, you don't need any knowledge.
Learning the basics is a waste of time"

Wayne

.p.s. Reading "popular" level science books can provide valuable context and
can stoke your interest, but they can only take you so far. Reading 100
popular level books does not, as some seem to believe, equvalent to
a degree, or does it make you much more than a cocktail party expert.
Stretch and get some good textbooks.
Excellent point.

I have noticed that some of the more recent popularizations of physics, written by good physicists tale some pretty heavy-duty liberties with ideas that have not been proved, particularly in string theory, and use conjectures as facts to reach conclusions that out to themselves be stated more tentatively. I am of the opinion that Susskind is guilty of that infraction in his book The Black Hole War, where it seems to me that he uses Maldecena's conjecture of the AdS/CFT correspondence as a fact. It is a good book, but I think it fails to make clear what is established and what is not. Since what is not is used to support his position, the oversight may be deliberate, althought I don't know for sure. To be fair I should probably note that Hawking also appears to assume th AdS.CFT correspondence is valid in his concession of the bet regarding the blackhole information problem.

Some of the popularizations are very good, but one needs to read then with some skepticism and some ability to read between the lines.
 
D

drwayne

Guest
When I was in high school, I had the random dumb luck to meet a girl, through whom I got
to meet an interesting older gentleman - who happened to be named Isaac Asimov

I never got to just hang out with him much, but I fell in love for a time with his non-fiction.
(I was never as wild about SciFi as Larry Niven). In the end, reading his books about
physics, particles etc. probably led me to become a physics major. (I started as
a math major)

Wayne
 
D

DrRocket

Guest
drwayne":2ne79jf7 said:
When I was in high school, I had the random dumb luck to meet a girl, through whom I got
to meet an interesting older gentleman - who happened to be named Isaac Asimov

I never got to just hang out with him much, but I fell in love for a time with his non-fiction.
(I was never as wild about SciFi as Larry Niven). In the end, reading his books about
physics, particles etc. probably led me to become a physics major. (I started as
a math major)

Wayne

That is pretty cool.

I have never read Asimov's non-fiction, but I really liked The Foundation trilogy. What I have heard of his non-fiction is good.
 
Y

yevaud

Guest
Actually, his non-fiction is notably excellent. :)

Wayne, a story back to you. Years ago, I used to take walks all the time along Boston's Esplanade, along the Charles river. Quite by accident, I struck up an acquaintance with Dr. Phillip Morrison and his wife Phyllis, who would take him there almost daily in his wheelchair. He was a very nice guy, piercing blue eyes, and much to say.

I also once shared a bottle of Champagne with Dr. Margaret Geller and a Grad. student, up on the BU observatory roof deck on the 4th of July.

Doc, any stores of your own...?
 
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