Re: Not quite magic physics [was Re: Quantum Computers]

John Clark (
Sun, 22 Aug 1999 16:49:05 -0400

Hash: SHA1

Robert J. Bradbury <> Wrote:

>If your Neutronium "cylinder" were surrounded by a large number
>of particle accelerators whose beam emissions were
>perpendicular to the axis of rotation, and the force of the beams
>striking the outside wall of the cylinder were high enough, it would
>be impossible for the cylinder to "fly apart".

Interesting idea, might work, I'll have to think about that.

>what happens when a beam of protons (or I suppose neutrons if you
>want really high density beams) hits a neutronium cylinder?

Except for electrical charge a neutron star can be thought of as a big (very big) atomic nucleus. It's almost impossible to deduce from first principles what will happen when a neutron interacts with even a medium sizes atomic nucleus, like iron for example, that's why we need experiment. I don't think anybody has a clue as to what would happen when a neutron reacts with a nucleus 5 miles in diameter that's more massive than the sun, I know I don't.

>since a mass density above a certain level will generate a black hole,
>will an energy density equivalent to that mass density (by e=mc^2)
>do the same thing?

Yes, you are very perceptive and absolutely correct. As the wavelength of light gets smaller the energy gets larger, and so does the mass, E =MC^2 so M= E/c^2. Thus at some point the wavelength is so small and the mass is so great that a mini Black Hole is formed with a singularity at its center. The energy of the photon where this happens is the Plank Energy, it is E= [hc^5/G]^1/2 = 1.22 *10^28 electron volts where h is the Plank constant divided by 2 PI, c is the speed of light, and G is the gravitational constant.

According to Heisenberg it's possible to get something for nothing, even in a vacuum you can borrow energy, but the more you borrow the shorter you can keep it. The amount of energy and the length of time you can detect its existence is related in the same way as velocity and position, the more you have of one the less you have of the other. In this way a vacuum is full of virtual particles, but the Plank Energy is a LOT of energy so you can't keep it for long.

The Plank Time is t = [Gh/c^5]^1/2 = 5.38 * 10^-44 second, after this the mini Black hole evaporates by Hawking radiation. The Plank Length is 10^-33 cm, the distance light can travel in the plank time.

This is a short distance, very short. If the universe was a thousand times as large as what we now observe it, then this super universe would be to a proton as a proton is to the Plank Length.

Now that's small, but what if we wanted to go even smaller? The singularity in the center of the mini black hole is a place of infinite spacetime curvature, its a true mathematical singularity, so that means our current laws of physics can't tell us what's going on when things get that little, to do that we need a theory of quantum gravity and we don't have that yet.

John K Clark

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