Paging Mr. Cochrane

[Navigator]

Looks like some progress is being made...

http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/08/16/scispeed116.xml

[blacknblue]

"quantum tunneling"

In other words, they "tunnel" through Hilbert space.

In Star Trek lingo, they drop into subspace.

Warp drive is here.

[Rigil Kent]

Whoa. Cool.

[Kevin Thomas Riley]

Cool, if it turns out to be correct. But I must ask, does "microwave photons" weigh anything?

[JadziaKathryn]

Wow. That's something, alright. Mind you, it's a long way from being able to jump a few particles to a whole ship, but Rome wasn't built in a day. Or a century.

For instance, an astronaut moving faster than it would theoretically arrive at a destination before leaving.

Does anyone understand that? I sure don't.

[Elessar]

Hilbert space isn't subspace... it's a kind of mathematical space. Lemme go read before I say anymore.

[evcake]

This is bizarre - I'm on my break reading this post, and a friend comes up on his break and tries to explain the theory of oscillating universes - or is it dimensions - to me. Bewildered here.

[cherryblossomjen]

I realize this discovery, if it proves true, is still in its baby stages. But still -- it's so cool!

[Elessar]

I can't find some of the details you're referring to... like, the article I see doesn't mention Hilbert spaces? Is there a more complete version somewhere?

This stuff is really cool and NOT understood at all. But it's not completely new either, we were talking about it at Cherry Hill, Y2kelly's hubby and I were familiar with it and explained it to the skeptical group! I think this research has been around, I'm gonna ball-park about 5 years.

Because they didn't mention the previous research, this must be in some way different... I'm gonna go on a hunt for some details...

Oh, I can describe, however, what quantum mechanical tunneling is, for anyone who's curious.

"Tunneling" can be explained very simply by saying that it's the ability of a particle to move THROUGH a "wall", when it shouldn't be able to. (In practical experiments, most commonly an electron is used because this explains many phenomena we see, such as radiation). The fact that tunneling is POSSIBLE is a complex question, that I'll answer after my little analogy.

It's not really a wall, in reality it's a "potential barrier" but the analogy of trying to put your physical hand through a wall is equivalent to trying to put a charged particle like an electron through a "potential barrier" that is "higher" than it is, in energy. Another good classical analogy is of a ball rolling up and down a half pipe, like that skateboarders skate on (like a 'U'-shaped road only longer). If the ball is dropped exactly at the top of the well, it will roll down it, rise up the other side, but it won't fly out because it can only go as high as it was dropped from, that's a little bit of common sense but also a consequence of conservation of energy/momentum. If the ball could tunnel like an electron can, it could jump THROUGH the barrier and come out outside of the half-pipe. That's essentially what a tunneling electron does.

Actually, this fact is part of what lead to the suspicion in the early 20th century that there was some new physics going on in the atom because Baquerel and others were observing radiation in the 1880's and 90's but when the mathematicians got their hands on the data and put it together with the Coloumb laws for electrostatics and basically said "how much radiation SHOULD we see come out of a nucleus?" they observed far MORE radiation coming out than the known laws of physics (at the time) predicted. The explanation for this was quantum mechanical tunneling, because if the particles in the nucleus (which are what become the radiation that we observe and measure the intensity of) have a certain energy and there is a certain energy level barrier keeping them in. So physicists said, "Ok with this much energy, then only ___ many particles will irradiate out of the nucleus and escape the nucleus' electrical potential well" but what they didn't know yet was that the particles inside didn't have to reach that level to be able to escape, they only had to reach "almost" that level, where they were able to possibly tunnel out. So a much higher number of particles escaped than the laws at the time would have predicted.

The question of exactly when and where a particle can do this is really an iconic symbol for the whole "probabilistic" nature of quantum mechanics that made (and still makes) so many people, philsophers AND physicists uncomfortable. It's of course almost universally accepted today (IMO the people who say QM's wrong are crackpots, because it has never failed to agree with experiment, not even on THIS crazy stuff. This crazy stuff violates Relativity, not QM.)

I can't give a complete qualitative explanation for exactly WHY this tunneling takes place. Part of it invokes the Uncertainty Principle because the value of the wave equation (the function defining the particle, which sounds weird) must be non-zero at the boundary, since the boundary is a definitive spatial location and zero is a definitive energy and momentum value. So if the wave function were zero at the boundary, the location and momentum would be simultaneously known, which violates the Uncertainty Principle, or more generally the Bell Inequalities (little discussed fact is that the Uncertainty Principle is just a specific application, a specific instance, of a more general rule, called the Bell Inequality, which holds for any two quantum variables that are not commutative - another long story). This statement "the wave function must be non-zero at the boundary" leads to the possibility that a particle can escape and "tunnel", in short.

But because when I took QM last year it was instructed to me in a mathematically rigorous presentation, the best way I can explain it most confidantly is in math terms, so if anyone wants THAT explanation, it would be this:

"Tunneling occurs because the probability distribution of the particle's wave function must be NONZERO outside of the barrier. Therefore, there exists a finite, non-zero probability that the particle's location can be outside of the barrier, and therefore tunnel. The probability distribution must be NONZERO in this region because there are requirements imposed upon the boundary conditions of any "well-posed" differential equations (such as that which governs the wave function) that are valid for the Hilbert space. These requirements are, among other things, that the wave equation's value at the barrier must equal the wave equation's value outside the barrier. This is also true of the first-order partial derivatives of the two wave functions, on each side of the barrier. The simplest function valid in the Hilbert space which fulfills this requirement is the exponential function (f=e^x), therefore the probability that the particle exists outside the barrier falls off exponentially as the particle's energy level relative to the barrier height goes down. In other words, the particle is more and more likely to tunnel through the barrier as its actual energy value approaches the height of the barrier, but less exponentially less likely as the particle's energy level relative to the barrier height gets lower.

A corollary to this which seals the deal for a non-zero probability distribution is the Uncertainty Principle, which prohibits the functions on each side of the barrier to being equal, but "equal to zero". As explained above, the UP prohibits the position and momentum of this particle from being known exactly, which fundamentally requires that its momentum at the barrier be NONZERO."

As you can see, there is no overarching metaphysical truth to this concept that makes it intuitive and divine. It's just kind of arbitrarily mathematical, for how incredibly profound it is

[Elessar]

By the way, the above doesn't explain why this experiment allows microwaves to go FTL... I haven't figured that out yet, I can't find a longer article.

[rogue]

*snap crack*

Elessar - you just broke my brain.

[justTripn]

True enouph, Y2Kelly's husband and Elessar were talking about this up at the convention (faster than the speed of light travel) in Cherry Hill, and I didn't believe them!

I'm glad to be wrong

[Linda]

Uh, the part about arriving somewhere before you leave the place you were starting from? Non physicist talking here, obviously... Wouldn't that jump to what they were talking about in the VOY series as warp 10? If you arrive before you leave, why bother with warp 1 through 9, where it is taking you at least some time, sequentually, to get from point A (say Earth) to point B (say Vulcan)? Or am I missing the whole point somehow...again.

[JadziaKathryn]

Uh, the part about arriving somewhere before you leave the place you were starting from? Non physicist talking here, obviously... Wouldn't that jump to what they were talking about in the VOY series as warp 10? If you arrive before you leave, why bother with warp 1 through 9, where it is taking you at least some time, sequentually, to get from point A (say Earth) to point B (say Vulcan)? Or am I missing the whole point somehow...again.

Then we can miss the point together, Linda. Theoretical math is complicated enough without addin in time travel. How can you arrive somewhere before you leave? Then you couldn't leave, so you'd never get there.

[Elessar]

Uh, the part about arriving somewhere before you leave the place you were starting from? Non physicist talking here, obviously... Wouldn't that jump to what they were talking about in the VOY series as warp 10? If you arrive before you leave, why bother with warp 1 through 9, where it is taking you at least some time, sequentually, to get from point A (say Earth) to point B (say Vulcan)? Or am I missing the whole point somehow...again.

I don't think you missed the point, you're absolutely right. This IS FTL travel only, it's not FTL travel in the "warp drive" sense because in Star Trek they avoid the relativistic effects of travelling at faster-than-light speeds by inventing the concept of subspace and how they're not really moving FTL in real space. That's the whole thing about how they project a warp field around their ship which pushes them into subspace and then they propel themselves through subspace, without ever really MOVING in real space. That's the theory of actual warp drive anyway, or in the real world as it's called the Alcubierre Drive.

"Arriving before you left" sounds really strange and I think if you used this kind of technology on manned spacetravel to other planets, it would ...I think... allow you travel backwards in time, because if you travelled to Mars at some speed that made you arrive there 1 year before you left, and then used the same speed to come back to Earth, you'd arrive a total of 2 years before you left Earth the first time.

But, the upside to this is that if you configured the speed relative to the distance you are travelling just right, you should be able to arrive at Alpha Centauri (which is 4.2 LY away) just a few days after you left instead of 4.2 years after you left, but you would still technically have gone "back in time", you'd just have gone "back" from 4.2 years in the future, back to some number of days after you left. You'd just NOT go as far as as before you left, you'd just go as far back as right after you left. That make any sense? But this is some method of sending PHOTONS faster than light, not people, so, it's kind of an immaterial discussion anyway. The benefit to sending a signal faster than light is, obviously, you've just invented subspace radio

This kind of stuff is really opening the door to some of the biggest secrets about how time is related to space and the speed of light and why that is, and all that goofy stuff.