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Hyperdrive Propulsion Could Be Tested At the LHC
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."
I think most/all of us take the term "hyperdrive" to imply FTL speeds.
This technology doesn't claim to achieve that.
It could be tested at the LHC if it ever manages to stay working for more than a month at a time, that is. :(
"calculated that a stationary mass should repel a particle moving towards or away from it at more than half the speed of light"
So, how do I slow down while going half he speed of light?
I see the advent of a new industry: space crash landings
"Our goal each year should be to increase the number of goals we set for ourselves!"
With something so simple as to elastic collision, who would have thunk it?
Theoretically it makes sense, and what's cool about it is that it can be done with today's technology.
Pretty cool.
Next thing you know we'll have Romulans visiting. I'm liking all of this already..
Previewing comments are for sissies!
There's a hyperdriven black hole careering all around Northern Europe? That's a hot mess waiting to happen.
Apart from being a potential nifty space drive, it would also provide a new test of General Relativity. This is far more likely to get it done as a real experiment at the LHC, than a new space drive.
Unless we use a Bussard Ramjet to collect interstellar dust...
It pays to be obvious, especially if you have a reputation for being subtle.
And now they're getting the theory down for building it.
Its only a matter of time (pun intended) till this plays out and turns into the world's first hyperdrive.
While testing this on the ground, just make sure you're not actually moving the Earth...
------ The best brain training is now totally free : )
Where hyperspeed was possible unless there were ships or asteroids nearby. In that case you became "mass locked" So it turns out that more than just a gimmick to skip the boring bits of the game, mass does indeed interfere with fast moving objects.
I'm sure someone posting Anonymously on /. has the courage to stand up to thugs.
Not a typewriter
If you want another "spacecraft carries its fuel" exception, check out magsails.
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.
The ONLY exception to this is the "solar sail" concept, which relies on an external source of propulsion.
I believe the idea here is to have a particle accelerator in orbit that will be fired past the spacecraft it is accelerating, so it is analogous to a laser-pumped solar sail. It's also best to think of this as a potential tool for accelerating really low-mass instrument packages intended to do fly-bys of nearby stars, which could be scientifically useful.
The rest of your post sounds remarkably like statements by people back in the '70's that we'd never be able to image the disk of even nearby stars, much less discover or image planets around them.
It may be that what the author is proposing is impossible. There are a number of things in the paper that look highly sketchy to me, but GR ain't my field. Even so, while this method of acceleration for interstellar exploration may not work, the one method that is certain not to work is never bothering to try.
Blasphemy is a human right. Blasphemophobia kills.
Oh, you beat me to it. I posted nearly the same point, but apparently you were posting at the same time. Your write up is better, anyhow. Great wiki link, thanks.
There's no limit to how much energy you can put into your propellent though. If you had Sufficiently Advanced Technology you could put a huge particle accellerator on your spaceship and send your exhuast out behind you at 99.999999999% the speed of light which, in fact, gives you a KE > 1/2m*V^2 due to relativistic effects. In fact, you could accelerate a million ton spacecraft up to .5 c with half a kilogram of propellent if you could put enough energy into it.
um... no?
kinetic energy doesn't follow that formula at relativistic speeds, which the article is explicitly about.
In fact, you could accelerate a million ton spacecraft up to .5 c with half a kilogram of propellent if you could put enough energy into it.
The question then becomes, how much does that amount of energy weigh?
OK. Me first. Got dibs on Andromeda. Poor chaps what will they do when they discover that we had filed the plans to build a highway through them and taped it to the underside of a sink in an unused bath room in a dark basement guarded by leopards?
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Zephram Cochrane?
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. 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.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
Not to mention that Hilbert was already preoccupied with the sphere packing problem, so at that time he had no spare balls which he could have employed in solving other problems.
Ezekiel 23:20
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 are something else entirely) material (all reflecting surfaces inward) and concentrate energy arbitrarily.
The white side reflects light, the black side absorbs it...
Once you reach the same temperature as your surroundings, you'll radiate as many photons as you absorb on the black side, and not go anywhere. If there's any anisotropy in the surrounding radiation field, you can use that to move around (but that's just called a solar sail for the common dipole case).
The Scientist's name is Felber, therefore the small fraction of light speed drive would likely be known as the Felber Drive.
If that doesn't sound sexy enough for you try the Hilbert-Felber Drive.
If you really want it to be metal, stick an umlaut in there somewhere.
I'm a practical guy. When you reach (I'll be generous) 1% c (3,000 kms-1) with your spaceship, I'll think about revising the laws of Newtonian physics.
s/practical guy/guy that refuses to believe 100 years worth of scientific experiments by people far smarter than anyone here/
Of course, your example just shows you don't know what he's talking about. You build the solar collectors in orbit around Mercury, and then aim the laser at the solar sail in deep space.
Robert Forward even showed how you can use one of them to decelerate when you get where you're going - basically, you release about 3/4 of your lightsail, and focus that section so that the laserlight, reflected off the larger section of lightsail shines on the smaller one, decelerating it relative to your start point.
"I do not agree with what you say, but I will defend to the death your right to say it"
The point of the drive is not that it enables light speed, or that it saves energy, because it doesn't do either.
The point of the drive is that it would accelerate you and you *don't* feel it!
The drive would accelerate you by gravity. Just like the International Space Station astronauts are still falling towards the Earth, but they can't feel it- you can't feel relativistic gravity either.
So you could accelerate at 1000 times the Earth's surface gravity if you wanted, and not even spill your coffee (potentially, if it works, and it should do).
Of course scaling up an effect that is only faintly sensed on an accelerator the size of the LHC is left as an exercise to the reader ;-), but it's fundamental research and you never know where it could lead.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"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.
You believe wrong. If you had read the damn paper, you'd have seen that the idea is that a mass much larger than the spaceship moving at relativistic speed can repel the spaceship, accelerating it to a speed much higher than its own, while the spaceship itself will not feel the acceleration (it will be in free-fall condition), with the exception of tidal forces.
"Politicians and diapers must be changed often, and for the same reason."