Theoretical Physics [OT thread]

[Derek]

Negative mass.

Or imaginary mass.

It depends on how you look at the equations.

By the way, by imaginary, I mean i, as it sqaure root of negative one style imaginary.


Derek

Physics is fun!

[apache]

"Kimball: I love it when engineers talk physics. It adds humor to my day..."

Hmm, us engineers love it when scientists try to talk about theoretical impossibilities. Nothing has yet proven to be impossible. Flying? Nope, done that. Speed of sound? Nope, done that too. Flat Earth? Heh, yeah right. The moon? Yep, been there. Weightless environments near the surface of the Earth? Thats old news. Some day we will be saying the same thing about going faster than c.
Some things I would never hope for, though, are time travel (throws all conservation laws out the window, while creating fantastic paradoxes), getting 'out' of a black hole (you have a spec of dust that was your space ship, try getting that out of infinite gravitational force), and creating matter/energy (how do you create something from absolute nothing?).

[Suicide Junkie]

Hate to tell you, but black holes do emit stuff and lose mass.

Hawking Radiation, where the black hole tends to absorb negative energy (and hence mass) from just outside the event horizon, and release positive energy(mass) to the environment.

Just one more thing to include in the list of not-impossible things.

[Derek]

Besides, a black hole is not an area of infinite gravity. It is an area where, after you go through the so-called 'event horizon', the escape velocity is greater than c, the speed of light.

Thats all.

Derek

[Suicide Junkie]

It may have infinite density at the centre, but it only has finite mass.

If it had infinite mass, the entire universe would be inside the event horizon. (as soon as the gravity's effect spread out)


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PS. as for the 'weightless environments near earth' Might you be referring to the Vomit Comet, or something more dramatic that I can't remember?

[This message has been edited by suicide_junkie (edited 01 March 2001).]

[dmm]

quote:

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Originally posted by suicide_junkie:
as for the 'weightless environments near earth' Might you be referring to the Vomit Comet, or something more dramatic that I can't remember?

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He might be referring to the demos where they used REALLY strong magnets to levitate little frogs. The upward force was due to the magnetic field causing the spins of all the froggie's atoms to line up, and they could tune it to exactly counteract the downward force from gravity. So, from the frog's point of view, it was weightless. They won't be using it to train astronauts anytime soon, though, because the region of uniform field is small compared to the size of the magnets.

[Suicide Junkie]

Hey, thats a ready-made artificial gravity for spaceships!

Just scale it up ten times, and you've got a Grav-bed you can set to 1g for when you sleep in orbit. Build it with a superconductor, and it won't use up any electricity once its running, either.

You could also use it for when you're boosting to orbit, to cancel the 14g peak acceleration.

With a nuclear/antimatter fuelled engine, you could run continuously at high g's without crushing your crew.

Heck, maybe thats what SE4 races use when they go from a tiny moon, to a huge Rock world.