# Why aren't electrons considered black holes ?

1. Jun 20, 2006

### Quaoar

Why aren't electrons considered "black holes"?

They have mass, so there should be a distance that's close enough to the electron where the escape velocity is greater than the speed of light. So, therefore, shouldn't electrons (and all other fundamental particles with mass) be considered tiny little black holes?

Last edited: Jun 20, 2006
2. Jun 20, 2006

### Staff: Mentor

Well, if you calculate what that distance is, you'll probably find it to be so small as to be meaningless. Below a certain distance and you're smaller than the smallest wavelengths of EM radiation.

3. Jun 20, 2006

### actionintegral

There are a lot of questions about electrons that remain unanswered to this day. For example, when you try to model an electron as a tiny charged sphere, things break down. For my part, I just don't go there!

4. Jun 20, 2006

### George Jones

Staff Emeritus
Results of scattering experiments are consistent with the electron being a point particle, so is an electron a black hole? This very interesting question probably requires a quantum theory of gravity for a definitive answer.

Some physicists have modeled an electon with a Kerr-Newman (i.e., charged and spinning) black hole, and I think this gives the correct g = 2 gyromagnetic ratio.

Examples of possible problems with quantum theory:

What if the electron wavefunction is non-zero outside the event horizon?

Hawking radiation from an electron black hole?

Uncertainty principle does not allow?

All right - who's going to step up to the plate and supply the required quantum theory of gravity?

5. Jun 20, 2006

### actionintegral

These would be good questions for Mr. Sweetser whose work is in the Independent Research forum. What does his model predict?

6. Jun 20, 2006

### Garth

Why aren't electrons considered "black holes"?

Well, classically it all depends on what radius you attribute to the electron, if it is not to be treated as a point charge.

Throwing in some numbers to get an OOM feel for the question we find:

Classical radius of electron = 2.8 x 10-13 cm
Reduced mass of electron in H atom = 9.1 x 10-27 gm
G = 6.7 x 10-8 dyn cm2gm-2
c2 ~ 1021 cm2 sec-2

$$\frac{2GM}{rc^2}$$ = 4.8 x 10-43,

pretty short of the value "1" required for an event horizon...

Garth

Last edited: Jun 21, 2006
7. Jun 21, 2006

### sweetser

I'll write a more complete reply on the Independent Research forum where it belongs, but the answer is both simple and kind of general: if a theory of gravity is found that is consistent with quantum mechanics and is not the rank 2 field equations for gravity found in general relativity, in that case all the work done on black holes will disappear into a black hole of its own, never to reappear because the papers are not relevant to the description of Nature.

doug

8. Jun 21, 2006

### George Jones

Staff Emeritus
Misner, Thorne, and Wheeler points this out (with an exclamation mark!) on page 883.

However, a Kerr-Newman solution with the physical parameters of an electron would not actually be a black hole, as it has no event horizons.

9. Jun 21, 2006

### pervect

Staff Emeritus
IIRC Wheeler once suggested that an electron-positron pair (and other particle/anti particle pairs for that matter) could be the two ends of a wormhole. I think there are some problems with this idea - one that comes to mind is that it doesn't work so well unless every particle has an antiparticle, which is currently not felt to be the case.

10. Jul 4, 2006

### Flatland

I have always thought. Maybe electrons ARE naked singularities?

11. Jul 4, 2006

### Garth

Are you not 43 OOM out? - see my post #6.

And why should they be naked?

Garth

12. Jul 4, 2006

### Farsight

I think the Black Hole question is because of a "point particle" concept. I've never thought of an electron as a point particle myself so I thought I'd have a look on google. I found this. It looks interesting, but I'm not sure what I can trust on the internet these days. Garth, pervect, do you know if this article is truthful and reasonable? Is it common sense?

"The point electron used for convenience has additional problems called a "mystery" by Sellin. Concentration of the electron charge in a point would require an infinite amount of energy and an infinite force to balance the outward directed Coulomb Force. If the rest mass energy is infinite, then the equivalent mass (M) equal to energy (E) divided by the light velocity (c) squared must (by modern theory) also be infinite. But the rest mass of an electron has been measured, and it is not infinite..."

Last edited: Jul 4, 2006
13. Jul 4, 2006

### pervect

Staff Emeritus
That site looks fishy to me.

We have physics that work very well in the energy region accessible to us - even the most powerful colliders we have been able to build.

However, it is known that there are problems with extending this physics too far into high energies - or equivalently, at distances that are too close. (It takes a very high energy to get electrons that close to each other).

This is an area that I'm not as familiar with as I would like, but the Wikipedia article:

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

points out there are problems even in QED, at high enough energies.

So what we have, currently, is known as an "effective field theory".

This is perhaps more obvious for gravity, see for instance
http://arxiv.org/abs/gr-qc/9512024

which is about quantum gravity as such an effective field theory. But gravity is (apparently, anyway) not alone in being in the "effective field theory" boat.

14. Jul 4, 2006

### Parlyne

Farsight, your article is neither truthful nor reasonable. It misrepresents the current picture of particle physics and makes unsubstantiated claims about an unexplained "theory."

By my count, this article rates a 129 on the Crackpot Index.

15. Jul 4, 2006

### G01

Also their should be points for saying that the bible supports your theory.

"Earliest Model of the Atom?
The first chapter of Ezekiel’s book found in the Bible seems to describe rings in a way that is consistent with the most general features of atomic structure. The four rings described by Ezekiel have the same physical arrangement and orientations as the rings found in the Lucas model of the atom. The most important feature of the atom is its stability, a feature emphasized by Ezekiel for his rings. The hydrogen gas molecule consisting of two electrons and two protons is the most simple and abundant form of matter in the universe; and in the Lucas model, diatomic hydrogen gas “looks” just like the four rings described by Ezekiel."

Last edited: Jul 4, 2006
16. Jul 4, 2006

### Parlyne

Hmmm...

I was only counting on the one page. But, that would certainly count.

Of course, if I wanted to cover the whole site, I'd have to go through the papers they have posted. But, I don't really want to spend money to read crackpottery (or, should that be cracked pottery?). I suppose it's possible that they actually have something worth looking at in those papers (and would lose the 50 points for lack of concrete, testable predictions); but I doubt it, particularly since only one of their papers seems to have been printed anywhere and it was in a Creation Science journal.

There probably should be points for that, but the index doesn't seem to cover it. I wonder if Baez is open to suggestions for an expanded index.

17. Jul 4, 2006

### Garth

Points for being crackpot? As a theologian as well as a scientist I can confidently state that the above isn't even crackpot; it is complete lunacy.

Garth

18. Jul 5, 2006

### Farsight

Thanks for the feedback guys.

19. Jul 5, 2006

### BoTemp

One more thing

Just stumbled onto this thread. Garth's calculation is correct; the event horizon is 2GM/c^2 away from the center of a body, which must be > r in order for the calcuations to be valid and an event horizon to exist.

I wanted to point out that there are a few unknowns working here as well. For one thing, classical general relativity doesn't take quantum effects into account, so cannot be used at length scales this small. Secondly, as far as I know, the basic structure of an electron (or any fundamental particle) isn't known. The point particle model works only at scales >> than the "radius" of the electron. If one believes string theory, then an electron is a 1-D vibrating string and the question is moot.