- #1

- 3

- 0

p.s. A poor English learner from China wrote the post.Don't laugh at me :tongue2:

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter EmperorNeo
- Start date

- #1

- 3

- 0

p.s. A poor English learner from China wrote the post.Don't laugh at me :tongue2:

- #2

- 50

- 0

- #3

- 2,193

- 2

Frame-dragging?

- #4

- 50

- 0

- #5

- 5,432

- 292

This what Timur has said, in more detail.

Perhaps your friend is thinking of this. See the Kerr metric, which is the general relativistic description of simple rotation.

- #6

HallsofIvy

Science Advisor

Homework Helper

- 41,847

- 964

p.s. A poor English learner from China wrote the post.Don't laugh at me :tongue2:

Your English is

- #7

- 3

- 0

- #8

- 33

- 0

Just like a Kerr Black Hole! Its rotation change the gravitational field surrounding it!

- #9

- 5,432

- 292

Gravity always attracts according to theory, and we have no experimental evidence to the contrary. Centripetal acceleration might be thought of as repulsive, so if you can bottle that you're in business.

If gravity is propagated by spin-2 massless bosons, then the only way to shield the effects of gravity would be to make them acquire mass and so have a shorter range.

Professor Ning Wu knows about this, although his work is not considered mainstream.

see arXiv:hep-th/0207254 v1 29 Jul 2002

Abstract

The quantum gravity is formulated based on gauge principle. The model

discussed in this paper has local gravitational gauge symmetry and gravita-

tional field is represented by gauge potential. A preliminary study on gravi-

tational gauge group is presented. Path integral quantization of the theory is

discussed in the paper. A strict proof on the renormalizability of the theory

is also given. In leading order approximation, the gravitational gauge field

theory gives out classical Newton’s theory of gravity. It can also give out an

Einstein-like field equation with cosmological term. The prediction for cos-

mological constant given by this model is well consistent with experimental

results. For classical tests, it gives out the same theoretical predictions as

those of general relativity. Combining cosmological principle with the field

equation of gravitational gauge field, we can also set up a cosmological model

which is consistent with recent observations.

email address: wuning@heli.ihep.ac.cn

- #10

- 10,050

- 1,220

Some comments: a rotating black hole is more massive than a non-rotating one. For some formal justification, see for instance A wikipedia article about black hole thermodynamics. Note that dM includes a term that is equal to the angular momentum multiplied by the angular velocity - this is the formal justification for a rotating black hole having more mass than a rotating one.

A very rapidly rotating black hole, where most of the mass (or energy) of the black hole is due to rotation has a name: it is known as an extremal black hole.

Robert Forward proposed the idea of trying to create such an extremal black hole by rotating some form of atomic nucleus, I believe. Unfortunately, I don't have a specific reference for exactly what he proposed. No substance made out of atoms with chemical bonds has even a chance of being strong enough - you need nuclear bonding energies to have even a chance of being strong enough to hold together.

Such a very small black hole should, however, evaporate quickly (very quickly, one might even say explosively), which suggests that this approach shouldn't really work in the first place due to quantum effects.

I ran across recently a rather interesting article (which is rather technical) that points out that the failure mechanism of such a hypothetical rapidly rotating body can be understood in terms of quantum mechanical tunnelling:

http://www.iop.org/EJ/abstract/1126-6708/2005/05/014/

Thus, even nuclear material will probably not (if I am understanding this correctly, and if the article itself is correct) be strong enough to hold enough energy to form a black hole. Tunnelling to a lower energy state will doom the proposal of forming a small black hole by rotating a small body rapidly enough.

This doesn't have anything at all to do with anti-gravity that I can see.

A very rapidly rotating black hole, where most of the mass (or energy) of the black hole is due to rotation has a name: it is known as an extremal black hole.

Robert Forward proposed the idea of trying to create such an extremal black hole by rotating some form of atomic nucleus, I believe. Unfortunately, I don't have a specific reference for exactly what he proposed. No substance made out of atoms with chemical bonds has even a chance of being strong enough - you need nuclear bonding energies to have even a chance of being strong enough to hold together.

Such a very small black hole should, however, evaporate quickly (very quickly, one might even say explosively), which suggests that this approach shouldn't really work in the first place due to quantum effects.

I ran across recently a rather interesting article (which is rather technical) that points out that the failure mechanism of such a hypothetical rapidly rotating body can be understood in terms of quantum mechanical tunnelling:

http://www.iop.org/EJ/abstract/1126-6708/2005/05/014/

Thus, even nuclear material will probably not (if I am understanding this correctly, and if the article itself is correct) be strong enough to hold enough energy to form a black hole. Tunnelling to a lower energy state will doom the proposal of forming a small black hole by rotating a small body rapidly enough.

This doesn't have anything at all to do with anti-gravity that I can see.

Last edited:

Share: