Near Light Speed Travel Possible After All?

DrStrabismus writes "PhysOrg has a story about research that may indicate that close to light speed travel is possible. From the article: 'New antigravity solution will enable space travel near speed of light by the end of this century, he predicts. On Tuesday, Feb. 14, noted physicist Dr. Franklin Felber will present his new exact solution of Einstein's 90-year-old gravitational field equation to the Space Technology and Applications International Forum (STAIF) in Albuquerque. The solution is the first that accounts for masses moving near the speed of light.'"

Comments

Re:Make sure you account for everything

[Dogers]

Weapons don't need to stop..

Actual papers...

[QuantumFTL]

For more information, see Dr. Felber's recent works on arXiv.org:

Weak 'Antigravity' Fields in General Relativity
Exact Relativistic 'Antigravity' Propulsion

Personally I'm a bit skeptical about his claims, however energy appears to be conserved. This method uses gravitationally-mediated kinetic energy exchange - this is the same principle that allows gravitational slingshot to work.

Has Slashdot become crackpot central?

[Expert Determination]

The most obvious giveaway is

Felber's research shows that any mass moving faster than 57.7 percent of the speed of light will gravitationally repel other masses lying within a narrow 'antigravity beam' in front of it.

because, of course, no physical phenomenon can operate only for masses travelling above a fixed speed like that because such a phenomenon would violate Lorentz invariance. Therefore he's not actually using Einstein's equations which are fully Lorentz invariant. Note that I'm making weak assumptions here - I'm not even assuming the validity of Einstein's field equations, I'm just saying that this work doesn't follow from the equations he claims it follows from. That means he's made up some new physics, something completely untested, and is therefore a crackpot.

Re:Make sure you account for everything

[Arctic Fox]

I think you need to reevaluate that.

For a traveller on the ship it would only seem like months. For the people left behind it would be years.

Look here. http://members.tripod.com/wmhxbigguy/Theory/time.h tml

Re:Make sure you account for everything

[Plunky]

Surely time dilation effects would significantly lessen the amount of air and food that needs to be carried?

Re:Stopping

[mark_osmd]

You make the assumption that the dust mote would actually stop, only then would the bulk of the KE go into the target space ship. More likely is that since the KE of each atom in the dust mote is so much larger than the atomic bond energy holding the grain together, the dust mote to the spacecraft really behaves like a very densely packed bundle of cosmic rays. If the spacecraft walls don't stop individual particles of that energy (ie like cosmic ray protons) then it won't stop the dust particle. The atoms would go in one side, out the other radiating a small fraction of their relative energy as gamma rays as cherenkov radiation and compton radiation. The dust would go out the other side as a diverging cone shaped spray of plasma.