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Between the Idea and the Reality between the Motion and the Act falls the Shadow T.S. Eliot

Hyperdrive Propulsion could be tested at the Large Hadron Collidep


Thursday, October 08, 2009

The principle behind a novel form of spacecraft propulsion could be tested at the world’s most powerful particle accelerator.

In 1924, the influential German mathematician David Hilbert published a paper called “The Foundations of Physics,” in which he outlined an extraordinary side effect of Einstein’s theory of relativity.

Hilbert was studying the interaction between a relativistic particle moving toward or away from a stationary mass. His conclusion was that if the relativistic particle had a velocity greater than about half the speed of light, a stationary mass should repel it. At least, that’s how it would appear to a distant inertial observer.

That’s an interesting result, and one that has been more or less forgotten, says Franklin Felber, an independent physicist based in the United States. (Hilbert’s paper was written in German.)

Felber has turned this idea on its head, predicting that a relativistic particle should also repel a stationary mass. He says that this effect could be exploited to propel an initially stationary mass to a good fraction of the speed of light.

The basis for Felber’s “hypervelocity propulsion” drive is that the repulsive effect allows a relativistic particle to deliver a specific impulse that is greater than its specific momentum, thereby achieving speeds greater than the driving particle’s speed. He says this is analogous to the elastic collision of a heavy mass with a much lighter, stationary mass, from which the lighter mass rebounds with about twice the speed of the heavy mass.

What’s more, Felber predicts that this speed can be achieved without generating the severe stresses that could damage a space vehicle or its occupants. That’s because the spacecraft follows a geodetic trajectory, in which the only stresses arise from tidal forces (although it’s not clear why those forces wouldn’t be substantial).

That’s a neat idea, but little better than science fiction, were it not for one further corollary: Felber is proposing an experiment that could prove his ideas or damn them.

It turns out that when it is up and running, the Large Hadron Collider (LHC) will accelerate particles to the kind of energies that generate this repulsive force. Felber’s idea is to set up a test mass next to the beam line and measure the forces on it as the particles whiz past.

The repulsive force that Felber predicts will be tiny, but it could be detected using resonant test mass. And since the experiment wouldn’t interfere with the LHC’s main business of colliding particles, it could be run in conjunction with it.

While the huge energy of the LHC makes it first choice for such an experiment, Felber says the effect could also be seen at Fermilab’s Tevatron, albeit with a signal strength that would be three orders of magnitude smaller.

Perhaps that’s something to consider as a last hurrah for the old Tevatron, before they begin mothballing it sometime next year.

Ref: arxiv.org/abs/0910.1084: Test of Relativistic Gravity for Propulsion at the Large Hadron Collider


[no subject]

A colleague of mine asked if I thought this was possible or hokum. The authors own “paper” (unpublished preprint, linked above) contains a rather lot of self-references to other unpublished preprints, usually a sign of some level of crack-pottedness. Also, his own numbers in the abstract for this idea (an acceleration of 3 nm/s^2 for 2 ns) make this completely unworkable. That corresponds to a displacement of a test mass of 1.5 x 10^-35 m. The most sensitive displacement detectors are the laser gravitational wave observatories, each of which are a pair of perpendicular 10km Fabry-Perot cavities. These detectors have a sensitivity of about 10^-18 m. That’s seventeen orders of magnitude difference. On an amusing note, that displacement is actually the same order of magnitude as the “Planck length”. I can’t help but wonder whether the author engaged in some silly numerology in order to get it to work out that way.

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  • Re:

    could not mail the author- –
    but if the influence of a passing proton beam would be measurable than i beleive the trajectory of the beam would be changed also this way perhaps more than allowed for the on going experiments

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The “repulsive force” he attributes to Hilbert is simply a coordinate artifact of the Schwarzschild metric, related to the gravitation redshift as you approach a gravitating body.  There is a good reason Hilbert’s paper was forgotten, and that this guy’s papers haven’t been published.

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12/10/2009 - Posted by | science

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