FTL Currents May Power Pulsar Beams 236
thomst passes along news out of the recent AAAS meeting of a new explanation for pulsar beams that involves faster-than-light currents. Here are Los Alamos's press release and three related papers on the arXiv. "The new model explains the beam emissions from pulsars as products of superluminal currents within the spinning neutron stars' atmospheres. According to the authors' model, the current generated is, itself, faster than light, although the particles that compose it never individually exceed the universal speed limit, thereby preventing Einsteinian post-mortem rotation. The new model is a general explanation of the phenomenon of pulsar beam emissions that explains emissions at all observed frequencies (and different pulsars emit everything from radio waves to x-rays), which no previous model has done."
Re:FTL information (Score:5, Informative)
Not the big deal people make out of it ... (Score:5, Informative)
[ I'm referring to the concept of seeing something that moves faster than the speed of light, not anything else here, just so it's clear ]
Consider this situation --
You've got a big sphere. Let's say it's 93 million miles in radius (the size of our radius around the sun -- it's a figure we're all familiar with anyways.)
In the middle of this sphere is a man. He has a laser, and he's shining it on the sphere. Since the man is still, the laser is not moving.
But, then the man starts spinning, once per second. The laser takes about 8 minutes to reach the edge of the sphere, but once it does, the dot starts going around the outside of the sphere, once per second. If you do the math, that means the dot is moving 584,000,000 miles per second -- which is about 3100 times the speed of light.
The light from the laser is still going at the speed of light, but the dot appears to be moving at over 3000 times the speed of light. But it's just a location -- the spot that the laser is hitting right now -- it doesn't mean that something tangible is exceeding the speed of light, and therefore Einstein isn't proved wrong by it.
My point is, it doesn't require some really strange neutron star situation to picture a situation where something might appear to be traveling faster than the speed of light.
Re:FTL information (Score:5, Informative)
Sort of.
Try this for an analogy: imagine a circular wall around us located one light-year radius away. Point your laser pointer at the wall, then sweep it so that it points to another spot 1 light year away on the same wall. Do that in 1 second.
1 year later, a dot of light will appear on the wall. The dot will then exceed the speed of light, traveling 1 light-year in 1 second. If that dot also induced an electric charge, it will look like some sort of current pulse just traveled along the wall millions of times the speed of light.
So, you've created a current, faster than the speed of light, that appears to carry information FTL, but not in a meaningful way.
Re:FTL Information? (Score:3, Informative)
Uh... do you have any links to these "cracks in the wall"? Because the first couple pages of search results all just show the standard descriptions about why quantum entanglement isn't FTL communication...
Re:FTL information (Score:3, Informative)
It's light... it's a big wave, with its source at your laser.
The real solution to this "problem" is that you can't transmit information from point A to point B faster than light, despite the fact that the beam can change focus between A and B, faster than light. You can use the triangle inequality to show this.
Re:FTL information (Score:2, Informative)
Reading -- you're doing it wrong.
Point your laser pointer at the wall, then sweep it so that it points to another spot 1 light year away from the first.
1 light year = 1 light year
The angle swept was 1 radian, not Pi radians.
Re:FTL information (Score:5, Informative)
Maths. You are doing them wrong. The point of light will not travel 1 light year in one second. It will travel Pi light years in one second as it traces out a half circle with a radius of one light year. If you meant to indicate the linear difference, that is also wrong, it would have been 2 light years.
Reading: You're doing it wrong.
They did not say he was rotating the light source by pi radians. They said they were rotating the source so that it struck a point 1 light year from the original. The arc-length -- or linear distance, either way -- was in the statement of the problem. If you want to do maths, then you can work your way backwards to the total angular displacement and angular velocity. Your answer will be different depending on whether they meant a circular wall or a flat wall, but either way the statement of 1 year of displacement is not wrong and cannot be wrong.
Re:FTL information (Score:5, Informative)
Oh for heaven's sake, somebody post a car analogy!
Take yer hotrod up to about 25 MPH at night and spin some donuts. From far enough away, the headlights reflecting off the walmart wall will move way faster than 25 MPH, maybe 1000 MPH who knows.
Now does the cop give you a ticket for speeding because your headlight reflections are moving 1000 MPH? No, nothing was speeding. The reflection is just a mathematical construct that means nothing. The cop gives you a ticket for being a dumbass and disturbing the peace, not for speeding.
AAS, not AAAS (Score:2, Informative)
Re:FTL Information? (Score:5, Informative)
> it's kinda amazing in a historical sense that 'normal' people are even aware of physics at that level in even the most vague of ways
Have you spoken to any 'normal' people lately?
Normal people think 'Ghost Hunters' is a documentary.
Normal people believe computers can think, and wouldn't like robots in their town because of the danger of them revolting against humans.
If I ask my parents what Einstein did, they say he invented the atom bomb.
My next door neighbor asked me to not let my kids use computers between 7pm and 8pm because she doesn't want them to be able to watch her in the bath (wtf?).
Don't mistake common knowledge on Slashdot for knowledge that is common.
Re:FTL Information? (Score:5, Informative)
Yeah, it *is* the same stuff as always, it's only the distance that changed. It was theorized that the particles could *not* remain entangled for nearly that distance -- that makes all the difference.
It makes a huge difference as far as practical quantum communication channels -- which are "merely" secure channels where any attempt to eavesdrop on the sub-light information stream can be detected -- but zero difference as far as the theory of whether or not it can be used for FTL info transfer, which still remains a big "no".
The particles, once they reach their destination, will be under constant observation. When I want to send a signal, I make the particles on my end "react" in a pulse-width-modulation fashion, like Morse code. Their corresponding particle pairs on the other end will "untangle" at the same rate, but instantaneously.
The reason this doesn't work is that for the person on the other end to detect that the particle in their possession has become untangled, they have to interact with it which would destroy any entanglement were there to have been any. In other words, there is no way for them to tell the difference between the waveform collapsing because you made it collapse versus them making it collapse by checking to see if you made it collapse.
The only thing they know is that there is a correlation between whatever state they observe in the post-collapse particle and your particle... but they knew about that correlation when you gave them their particle to carry away with them at sub-light speed in the first place. All actual information was carried with the particles themselves at sub-light speeds.
Those links from the google search can provide more explanations, too. Suffice to say that all known methods of using quantum entanglement -- whether for communication, or "teleportation" -- involve things moving at sub-light speeds.
Re:Rigid Carbon Nanotube!!! (Score:3, Informative)
You just proved that there isn't such a thing as a rigid body. There is this upper limit, imposed by relativity.
You can make some calculations, about the electric pulse propagating through the matter at light speed, but they're trivial and boring.
Re:FTL Information? (Score:4, Informative)
Are you kidding? Many people did love and would love the idea of hidden variables! It'd be like telling the children there most certainly are presents in the closet, but presents they can know nothing about and must not peak. The kids would be angling for their first chance to get in there.
Hidden variables would mean a deeper understanding of which we are ignorant - fun stuff to keep chasing down.
No, it's not that Quantum Physicists just don't like Hidden Variables.
It's that a pretty clever chap figured out a way to test whether Quantum Physics involved Hidden Variables (without really needing to know much about them). Once he (and a few others) refined these ideas and actually did some tests, the results were clear. And as our instrumentation gets better over time, similar testing has more and more profoundly demonstrated Quantum Physics simply does not depend on Hidden Variables - it's just that weird.
Look up Bell's Theorem.
Re:FTL information (Score:2, Informative)
Read this: http://www.eskimo.com/~billb/miscon/elect.html [eskimo.com]
and then come back to educate other /.-ers. I'm a civil engineer and even I didn't know some of the stuff in there. Did you know that electrons flow through metal at a few cm/minute? I sure didn't, but after reading this text a lot of other stuff made a lot more sense to me.