Can String Theory Explain Quantum Gravity and Fundamental Constants?

[Haelfix]

Jon, the last point was referring ot regular dust. Electrons won't undergo fusion, so they go straight to the white dwarf stage.

Actually, the white dwarf is still very much the same problem. You have mostly all electrons there as well, concentrated in a spherical configuration. The more mass you stick in, the more electrons you get and the smaller the radius becomes. Yet gravity still wins as you increase the mass (actually its not the electrostatic field that causes the supporting outward pressure, but rather quantum mechanics).

 

[jonmtkisco]

Hi Haelfix,

Actually, the white dwarf is still very much the same problem. You have mostly all electrons there as well, concentrated in a spherical configuration.

No I'm sorry, that isn't correct. White dwarfs are comprised of matter that contains an equal complement of protons and electrons. As a star undergoes collapse to become a white dwarf, its electrons separate from the nuclei, and both the electrons and nuclei are squeezed into a space that is smaller than the normal low-energy electron orbitals. This state of matter is called "electron degenerate matter." Perhaps that name is the source of confusion here.

With even further squeezing, the particles are compressed beyond the Chandrasekhar limit, and the electrons combine with the protons to form a soup that is mostly all neutrons. This neutron soup can be squeezed further to surpass the TOV limit, in which case the individual neutrons presumably are "crushed" and the structure may collapse into a black hole.

None of the above is directly relevant to a pure electron plasma. Since there are no nuclei, there are no electron orbitals at stake. And no neutrons can form.

I have repeated this description enough times that I hope by now I've made my point. An electron plasma is a different animal, end of story.

Jon

 

[hellfire]

The material I cited makes it very clear that an electron plasma's self-gravity could never cause it to spontaneously collapse even a little bit.

Sorry but I do not see that the material you cited is a rigorous treatment of this topic. At least I am reluctant to accept it as a proof.

 

[Haelfix]

Typically a white dwarf has a bunch of carbon and oxygen when it forms, however as you increase the mass of the star, the extra compression forces electrons to be stripped from the remaining nuclei, and you end up with a sea of electrons floating around the place.

So actually what you normally have is a thin outer strip around the White dwarf of mostly nondegenerate matter (read much of the nuclei), and the bulk is degenerate matter where the density of electrons is much, much higher than protons and neutrons and so forth.

If you look at the system from the interior, as I said, you have very much the same sort of thing. The more mass you put it, creates more electrons in the bulk and contrary to what you would think, actually *shrinks* the star.

 

[jonmtkisco]

Hi hellfire,

Sorry but I do not see that the material you cited is a rigorous treatment of this topic. At least I am reluctant to accept it as a proof.

Fair enough, I have not found any rigorous treatment of this specific subject. If you find one please let me know; of course it would supersede our non-rigorous discussion here. I am eager to learn if there are subtle effects we haven't accounted for.

At the non-rigorous level of our discussion, the logic in favor of the behavior I've advocated is far stronger than the logic against it. It is common knowledge that the electromagnetic potential of electrons and protons far exceeds their gravitational potential.

Jon

 

[jonmtkisco]

Hi Haelfix,

So actually what you normally have is a thin outer strip around the White dwarf of mostly nondegenerate matter (read much of the nuclei), and the bulk is degenerate matter where the density of electrons is much, much higher than protons and neutrons and so forth.

If you look at the system from the interior, as I said, you have very much the same sort of thing. The more mass you put it, creates more electrons in the bulk and contrary to what you would think, actually *shrinks* the star.

Yes I'm aware that it is believed that a certain amount of degenerate electron gas migrates to the core of a white dwarf. Then the collapse scenario becomes essentially what I have repeatedly described here as the "external force" scenario. An outer dense shell of (nearly) electrically neutral matter supplies the gravitational bulk which crushes an inner ball of electron gas. The electron gas is not crushed by its own gravity, it is crushed by the outer shell of nearly neutral plasma.

If there was a mechanism to remove the entire outer shell of nearly neutral plasma, the remaining negatively charged core of the star would not collapse, regardless of its mass. Instead it would fly apart at high acceleration.

Jon

 

[hellfire]

Hi hellfire,

Fair enough, I have not found any rigorous treatment of this specific subject. If you find one please let me know; of course it would supersede our non-rigorous discussion here. I am eager to learn if there are subtle effects we haven't accounted for.

At the non-rigorous level of our discussion, the logic in favor of the behavior I've advocated is far stronger than the logic against it. It is common knowledge that the electromagnetic potential of electrons and protons far exceeds their gravitational potential.

Jon

Ok, so far at our level of discussion I agree with you that if the relation between electrostatic repulsion and gravity remains unchanged at small scales then gravity will never become strong enough to make electrons collapse into a black hole.

 

[madmike159]

I can give you a very basic view of it, but I don't understand the maths behind it. In string theory it is believed that all particles are made up of very small strings (Sub Planck?) which vibrate in different ways to produce different effects/particles. If we can understand what vibrations make what particles it is thought that we would understand all of physics including quantum gravity. It could also explain why constants (like e and Pi) appear through out physics. In not an expert on this, but I'm sure some one will correct me if I'm wrong.