## Hyperdrive Propulsion Could Be Tested At the LHC 322 322

KentuckyFC writes

*"In 1924, the influential German mathematician David Hilbert calculated that a stationary mass should repel a particle moving towards or away from it at more than half the speed of light (as seen by a distant inertial observer). Now an American physicist has pointed out that the equal and opposite effect should also hold true: that a relativistic particle should repel a stationary mass. This, he says, could form the basis of a 'hypervelocity propulsion drive' for accelerating spacecraft to a good fraction of the speed of light. The idea is that the repulsion allows the relativistic particle to deliver a specific impulse that is greater than its specific momentum, an effect that 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. Unlike other exotic hyperdrive proposals, this one can be tested using the world's largest particle accelerator, the LHC, which will generate beams of particles with the required energy (abstract). Placing a test mass next to the beam line and measuring the forces on it as the particles pass by should confirm the theory — or scupper it entirely."*
## ! hyperdrive (Score:5, Informative)

I think most/all of us take the term "hyperdrive" to imply FTL speeds.

This technology doesn't claim to achieve that.

## Re:Oct 8th, Warp Drive Day. (Score:4, Informative)

Its only a matter of time (pun intended) till this plays out and turns into the world's first hyperdrive.

It's only a matter of time until we're all consumed in a fiery death

## Re:! hyperdrive (Score:2, Informative)

How could parent be redundant? It's 1) stamped two minutes after the article's post time, and 2) currently the only comment based on the common SF use of 'hyperdrive' as a synonym for 'superluminal.'

(Normally I would correct such clueless moderation, but I posted in this thread already.)

## Re:But (Score:2, Informative)

If you want another "spacecraft carries its fuel" exception, check out magsails [wikipedia.org].

Backing up, though, I'll see your KE = 1/2 m v^2, and raise you E = mc^2. Consider that 1 kg matter + 1 kg antimatter yields 1.7975 * 10^17 J of energy. A mere 20 kg of reactants would yield enough energy to accelerate 90 metric tons -- somewhat more massive than the Space Shuttle orbiter -- to 0.01c. 2 metric tons of reactants vs 90 metric tons of total mass gives 0.1c. Chemical propulsion doesn't seem to be a viable mechanism long-term, as you point out, but the energy-vs-mass problem overall isn't as dire as you indicate.

Humanity has been attempting spaceflight for only 50 years now.

Interstellar travel will happen.It almost certainly won't be in our lifetimes, but don't count us out yet.## Re:But (Score:5, Informative)

um... no?

kinetic energy doesn't follow that formula at relativistic speeds, which the article is explicitly about.

## Re:! hyperdrive (Score:3, Informative)

I agree, it should be downgraded to the less impressive and more hierarchically correct megadrive or perhaps superdrive.

What do the Sega Genesis [wikipedia.org] and Apple DVD recorder [wikipedia.org] have to do with relativistic spacecraft engines?

## Re:! hyperdrive (Score:3, Informative)

## Re:But (Score:4, Informative)

That's the classical formula, which is asymptotically accurate at speeds much below the speed of light.

The real formula is messier, as you'll see at the Wikipedia article [wikipedia.org]. There's currently no way around that one, but we might find a more precise formula later.

If the classical formula was completely correct, then the kinetic energy of a particle at lightspeed would be half the relativistic energy of its rest mass, and therefore modern particle accelerators (which can be seen as adding kinetic energy to particles) would achieve speeds far faster than light. This doesn't happen.

There's no inherent limit to the amount of kinetic energy we can put into a particle of any mass. The issue for interstellar travel is getting the energy, not applying it. Energy on that scale has an awful lot of mass.

## Re:Passive propulsion (Score:2, Informative)

A better idea would be a mirror sail that transmits light on one face, and reflects it on the other.

The 2nd law says no. I could make a box out of your one-way mirror (note that real "one-way" mirrors [wikipedia.org] are something else entirely) material (all reflecting surfaces inward) and concentrate energy arbitrarily.

## Re:! hyperdrive (Score:4, Informative)

But I'm already going that fast.

I posted this message 61,282 years ago.

## Re:But (Score:2, Informative)

## Re:! hyperdrive (Score:2, Informative)