http://www.physorg.com/news66582110.html
If that animation is accurate, what would happen if ("magically" - maybe using an LCD?) the light pulse was prevented from entering the wire as soon as it was detected leaving it?
[FONT=Arial]
we think that our universe the connexion of space and time( space-time ) derived of possible violation of opperatorPT and does appear two distictis torsions asymmetry that generates the curvatures of space-time " forward in time" and "backward in time".then in these curvatures the past and future alredy exist.
the universe multi dimensional is generated by two torsion disticts,and these deformation generate infinities "two torsion disticts".
we thinh that time also is generated by groups of infinities subtimes connected the subspaces correspondent.
antonio pocobi
we think that our universe the connexion of space and time( space-time ) derived of possible violation of opperatorPT and does appear two distictis torsions asymmetry that generates the curvatures of space-time " forward in time" and "backward in time".then in these curvatures the past and future alredy exist.
the universe multi dimensional is generated by two torsion disticts,and these deformation generate infinities "two torsion disticts".
we thinh that time also is generated by groups of infinities subtimes connected the subspaces correspondent.
antonio pocobi
Turns out that any physical way of cutting off the pulse... like dropping a little gate, turning on a LCD, cutting the cable, etc. has to be so fast to cut off the first pulse that the act of stopping the pulse will make a new pulse of it's own... and that could be the one coming out of the other end of the cable.
What I don't get is: why can't we use this to send info faster than light?
What if I send 2 pulses? If I get 2 detectable, distinguishable pulses instantly out the other side I can send binary.
Yes, the bit rate won't be any faster than I sent them in, but I didn't have to wait for them to come out the other side. I could run a cable from here to Mars and not have to wait on the delay with those two robots...
What I don't get is: why can't we use this to send info faster than light?
What if I send 2 pulses? If I get 2 detectable, distinguishable pulses instantly out the other side I can send binary.
Yes, the bit rate won't be any faster than I sent them in, but I didn't have to wait for them to come out the other side. I could run a cable from here to Mars and not have to wait on the delay with those two robots...
Whenever you see the words "faster than light", you should ask two questions:
Q1: Are they talking about the speed of light in a VACUUM?
A1: No, they're usually talking about the speed of light in some sort of material like glass, which is typically a third slower than light in a vacuum. The speed of light in a vacuum is the real speed limit.
Q2: Are they talking about phase velocity or group velocity? If the article doesn't say, then either the reporter didn't ask the right questions, or the researcher is trying to mislead investors.
Group velocity (q.v.) is the speed of an actual information-pulse, when you factor out reflections and stray ripples.
Phase velocity (q.v.) is an illusory movement of wavelets which SEEM to move faster than light, but actually don't. You can see an example of this at the front of a moving row-boat traveling faster than its own wake. The wake falls behind the boat on either side -- that's the group velocity. If you 'send a signal' by throwing a pebble in the water, the ripples fall behind the boat -- again, group velocity -- the speed of an information-carrying wave in water.
But if you look at the bow wave, you see wavelets that SEEM to be traveling faster than the larger wave they're part of. They appear at the back of the bow wave, move quickly to the front, and disappear. These are phase-velocity waves, and their high velocity is illusory. They don't carry information, because they don't appear until an information-carrying wave has already moved past, and disappear when they reach the front of the msin wave.
Most materials have a constant index of refraction, which tells you how much light slows down in that medium ( Snell's Law of refraction ). In a 'tricky' medium, the index of refraction can be shifted up or down using laser pulses, or can even be made negative. The catch is that the laser pulse which performs the trick are themselves traveling slower than light in a vacuum, so none of the ripple effects behind them can carry information faster than the causative wave -- what you get is a 'bow wave' with some phase-velocity ripples running around inside it.
There's nothing mystical about light slowing down ( index of refraction suddenly made large or very large with respect to that particular frequency of laser light ).
There's nothing mystical about STOPPING laser light -- which is simply captured by the atoms in a laser rrystal. A laser crystal can emit laser light, and under some circumstances can re-absorb it, transferring the energy of the light to excited electrons in the laser crystal. 'Stopped' light can essentially be stored and re-released.
There's nothing mystical about light traveling backward. A laser device called a "phase conjugating mirror", is described in _Scientific American_, January 1986. The phase conjugating mirror ( PCM ) creates a backward-moving clone of any light passing through it, referred to as "time-reversed light", which retraces the original path of the light.
Such devices are all very useful for optical computers, and that's why they're being funded / researched. Almost none of the researchers are aiming for faster-than-light effects, because laser effects work on well-known ( slower-than-light ) equations.
However there are always a few reporters who like to play with people's heads, by not explaining group velocity vs. phase velocity, and by playing with words so it sounds like somebody is doing FTL research. Again, general relativity only prohibits transfer of information faster than light in a vacuum. Quantum mechanics has a similar principle called the No-Communication Theorem -- which merely says that although quantum-entangled particles can 'agree' at a distance, they can't carry usable information. If you send one entangled particle to Alpha Centauri and measure the other one, the two particles will will 'agree' ( e.g. if one is spin up, then the other is spin-down. But since the measurement at Centauri comes out completely random, you still have to wait 4.2 years to compare results by radio, in order to 'decode' the information.
Every physics student has thought "there's gotta be a way...", and has eventually realized [often by trying it] that the 'usual tricks' don't work.
For better news on slow light experiments, backward light etc. see weekly Physics News Update at Amer. Inst. of Physics http://www.aip.org/physnews/update
Another good source on FTL questions is the the sci.physics FAQ
http://math.ucr.edu/home/baez/physics/
NOTE: When choosing science resources for your child, you might want to steer clear of sites that claim to offer 'science' information but don't actually have experts screening it. Some 'science' sites rely on user ratings to select their material, the problem being that flakes like to read what they hope is true, and many reporters cultivate 'tabloid science' readers.
Chris N writes:
"What I don't get is: why can't we use this to send info faster than light?
"What if I send 2 pulses? If I get 2 detectable, distinguishable pulses instantly out the other side I can send binary."
The catch is that when you chop the wave, the PERTURBATION travels at the slower group velocity, not the faster phase velocity. In practice, you're probably going to chop the wave by using an ultrafast laser pulse to turn a square of material opaque. OK, you've just cut off the forward-moving electromagnetic field passing through that square. Now suppose you have two computer-simulations you can compare, one if you don't chop the wave and one if you do chop it. Compare the simulations in slow motion. The change you introduced ( called a "perturbation" ) propagates slowly forward. It doesb't immediately come out the other side.
Now zoom the simulation on what's going on. Just beyond the chopping point, un-chopped light is still moving forward, at the speed of light in that medium -- those waves don't know you chopped the waves behind them. Other waves are coming the other way, toward the chopping point. They haven't gotten the message either that anything has changed.
Now zoom in further, to the atomic scale. Again you see the light waves traveling at their normal speed in the medium ( slower than in a vacuum ). More specifically, the light waves are following Maxwell's equations and quantum electrodynamics -- both of which are causing the PERTURBATION to advance slower than light. You notice that different wavelengths are present, because the experimenter has been monkeying with the index of refraction and whatnot. The differing wavelengths move through each other causing a vernier effect, a rapid interference-ripple that seems to move quickly, but isn't carrying the perturbation forward. In fact as your perturbation wave advances slowly forward, you notice that your perturbation has its OWN phase-velocity waves trapped inside, like the bow wave of the boat. Uour perturbation wave is undulating slowly forward ( group velocity ), quivering like jell-o as it goes ( phase velocity ). Such simulations are valid because they track perfectly with the experimental data.
You're correct in a sense that chopping the wave introduces a new wave -- and can be modeled as adding a cancellation wave. The catch is that you're not only creating a different wave -- you're starting a new WAVE PACKET, separate from the old one.
The act of chopping also 'chops off the tail' of each individual photon wave packet that has just passed through the guillotine -- but that merely reshapes the back end of the quantum wave packet(s), not the front end, if you play with a Fourier applet. There was an excellent article in _Scientific American_ several years back, showing how the wave packets look for a tunneling electron, and why you can't just 'clip' the trailing edge of a quantum wave packet to make the average wave packet go faster. No matter how you trim the ttail end, the leading edge of the wavepacket still can't arrive at the destination any faster than light -- and each time you apply a trim, you create a new wavepacket for the portion you sculpted. Your sculpting tool can't catch up with the portion of the wave that's already gone on ahead, because your sculpting tool ( an ultrashort laser pulse ) can only travel at the speed of light in a vacuum.
Tricks with phase velocity are a little like the Cosmic Used Car Lot illusion. The cosmic car lot is square, one light-year across, with a strong of lights running around it. All the lights are wired to your desktop. You can program the lights so that the light seems to race around the big square once per second, far faster than light. The catch is that when you turn on the power, it takes several months for the electricity to travel ( at the speed of light ) to all the lights on the square. So what you see is a 'bow wave' of illumination moving out from your desktop. Within that bow wave are racing waves of light chasing each other, but they don't carry any information for you because they've already been sent and you can no longer recall or change them. That's exactly what happens in a slow light experiment, when the experimenter sends pre-programmed waves on ahead to 'set up' the experiment for the target pulse, to make the target pulse slow down, stop, run backward or whatever.
--
A computer does what you tell it, not what you want.
Quantum mechanics does what it wants, not what you tell it.
Quantum computers will all have labels "Schrodinger's cat inside."
Q1: Are they talking about the speed of light in a VACUUM?
A1: No, they're usually talking about the speed of light in some sort of material like glass, which is typically a third slower than light in a vacuum. The speed of light in a vacuum is the real speed limit.
Q2: Are they talking about phase velocity or group velocity? If the article doesn't say, then either the reporter didn't ask the right questions, or the researcher is trying to mislead investors.
Group velocity (q.v.) is the speed of an actual information-pulse, when you factor out reflections and stray ripples.
Phase velocity (q.v.) is an illusory movement of wavelets which SEEM to move faster than light, but actually don't. You can see an example of this at the front of a moving row-boat traveling faster than its own wake. The wake falls behind the boat on either side -- that's the group velocity. If you 'send a signal' by throwing a pebble in the water, the ripples fall behind the boat -- again, group velocity -- the speed of an information-carrying wave in water.
But if you look at the bow wave, you see wavelets that SEEM to be traveling faster than the larger wave they're part of. They appear at the back of the bow wave, move quickly to the front, and disappear. These are phase-velocity waves, and their high velocity is illusory. They don't carry information, because they don't appear until an information-carrying wave has already moved past, and disappear when they reach the front of the msin wave.
Most materials have a constant index of refraction, which tells you how much light slows down in that medium ( Snell's Law of refraction ). In a 'tricky' medium, the index of refraction can be shifted up or down using laser pulses, or can even be made negative. The catch is that the laser pulse which performs the trick are themselves traveling slower than light in a vacuum, so none of the ripple effects behind them can carry information faster than the causative wave -- what you get is a 'bow wave' with some phase-velocity ripples running around inside it.
There's nothing mystical about light slowing down ( index of refraction suddenly made large or very large with respect to that particular frequency of laser light ).
There's nothing mystical about STOPPING laser light -- which is simply captured by the atoms in a laser rrystal. A laser crystal can emit laser light, and under some circumstances can re-absorb it, transferring the energy of the light to excited electrons in the laser crystal. 'Stopped' light can essentially be stored and re-released.
There's nothing mystical about light traveling backward. A laser device called a "phase conjugating mirror", is described in _Scientific American_, January 1986. The phase conjugating mirror ( PCM ) creates a backward-moving clone of any light passing through it, referred to as "time-reversed light", which retraces the original path of the light.
Such devices are all very useful for optical computers, and that's why they're being funded / researched. Almost none of the researchers are aiming for faster-than-light effects, because laser effects work on well-known ( slower-than-light ) equations.
However there are always a few reporters who like to play with people's heads, by not explaining group velocity vs. phase velocity, and by playing with words so it sounds like somebody is doing FTL research. Again, general relativity only prohibits transfer of information faster than light in a vacuum. Quantum mechanics has a similar principle called the No-Communication Theorem -- which merely says that although quantum-entangled particles can 'agree' at a distance, they can't carry usable information. If you send one entangled particle to Alpha Centauri and measure the other one, the two particles will will 'agree' ( e.g. if one is spin up, then the other is spin-down. But since the measurement at Centauri comes out completely random, you still have to wait 4.2 years to compare results by radio, in order to 'decode' the information.
Every physics student has thought "there's gotta be a way...", and has eventually realized [often by trying it] that the 'usual tricks' don't work.
For better news on slow light experiments, backward light etc. see weekly Physics News Update at Amer. Inst. of Physics http://www.aip.org/physnews/update
Another good source on FTL questions is the the sci.physics FAQ
http://math.ucr.edu/home/baez/physics/
NOTE: When choosing science resources for your child, you might want to steer clear of sites that claim to offer 'science' information but don't actually have experts screening it. Some 'science' sites rely on user ratings to select their material, the problem being that flakes like to read what they hope is true, and many reporters cultivate 'tabloid science' readers.
Chris N writes:
"What I don't get is: why can't we use this to send info faster than light?
"What if I send 2 pulses? If I get 2 detectable, distinguishable pulses instantly out the other side I can send binary."
The catch is that when you chop the wave, the PERTURBATION travels at the slower group velocity, not the faster phase velocity. In practice, you're probably going to chop the wave by using an ultrafast laser pulse to turn a square of material opaque. OK, you've just cut off the forward-moving electromagnetic field passing through that square. Now suppose you have two computer-simulations you can compare, one if you don't chop the wave and one if you do chop it. Compare the simulations in slow motion. The change you introduced ( called a "perturbation" ) propagates slowly forward. It doesb't immediately come out the other side.
Now zoom the simulation on what's going on. Just beyond the chopping point, un-chopped light is still moving forward, at the speed of light in that medium -- those waves don't know you chopped the waves behind them. Other waves are coming the other way, toward the chopping point. They haven't gotten the message either that anything has changed.
Now zoom in further, to the atomic scale. Again you see the light waves traveling at their normal speed in the medium ( slower than in a vacuum ). More specifically, the light waves are following Maxwell's equations and quantum electrodynamics -- both of which are causing the PERTURBATION to advance slower than light. You notice that different wavelengths are present, because the experimenter has been monkeying with the index of refraction and whatnot. The differing wavelengths move through each other causing a vernier effect, a rapid interference-ripple that seems to move quickly, but isn't carrying the perturbation forward. In fact as your perturbation wave advances slowly forward, you notice that your perturbation has its OWN phase-velocity waves trapped inside, like the bow wave of the boat. Uour perturbation wave is undulating slowly forward ( group velocity ), quivering like jell-o as it goes ( phase velocity ). Such simulations are valid because they track perfectly with the experimental data.
You're correct in a sense that chopping the wave introduces a new wave -- and can be modeled as adding a cancellation wave. The catch is that you're not only creating a different wave -- you're starting a new WAVE PACKET, separate from the old one.
The act of chopping also 'chops off the tail' of each individual photon wave packet that has just passed through the guillotine -- but that merely reshapes the back end of the quantum wave packet(s), not the front end, if you play with a Fourier applet. There was an excellent article in _Scientific American_ several years back, showing how the wave packets look for a tunneling electron, and why you can't just 'clip' the trailing edge of a quantum wave packet to make the average wave packet go faster. No matter how you trim the ttail end, the leading edge of the wavepacket still can't arrive at the destination any faster than light -- and each time you apply a trim, you create a new wavepacket for the portion you sculpted. Your sculpting tool can't catch up with the portion of the wave that's already gone on ahead, because your sculpting tool ( an ultrashort laser pulse ) can only travel at the speed of light in a vacuum.
Tricks with phase velocity are a little like the Cosmic Used Car Lot illusion. The cosmic car lot is square, one light-year across, with a strong of lights running around it. All the lights are wired to your desktop. You can program the lights so that the light seems to race around the big square once per second, far faster than light. The catch is that when you turn on the power, it takes several months for the electricity to travel ( at the speed of light ) to all the lights on the square. So what you see is a 'bow wave' of illumination moving out from your desktop. Within that bow wave are racing waves of light chasing each other, but they don't carry any information for you because they've already been sent and you can no longer recall or change them. That's exactly what happens in a slow light experiment, when the experimenter sends pre-programmed waves on ahead to 'set up' the experiment for the target pulse, to make the target pulse slow down, stop, run backward or whatever.
--
A computer does what you tell it, not what you want.
Quantum mechanics does what it wants, not what you tell it.
Quantum computers will all have labels "Schrodinger's cat inside."
we think that the continuum space-time is generated by two torsion distict that do generate particles and particles and both lorentz's transformations.it is the connexion of space-time is given by the connexion space and time through of strong violation of opperator PT=CPT and defined by non linear fields in space-time,generated by 2 -rotation systems in subspace-time of 8-dimension(octonions)complex and 16 dimension real that are projective for minkowkan imaginary in 4-dim. that violate causality due beakdown of pt,and therefore the existence superluminal signals.in that universe go forward in time and backward in time is not concrete,because "past" and "future" already there are into of continuities of space-time.
Antonio carlos motta
mott.phys@bol.com.br
Antonio carlos motta
mott.phys@bol.com.br
we think that the continuum space-time is generated by two torsion distict that do generate particles and particles and both lorentz's transformations.it is the connexion of space-time is given by the connexion space and time through of strong violation of opperator PT=CPT and defined by non linear fields in space-time,generated by 2 -rotation systems in subspace-time of 8-dimension(octonions)complex and 16 dimension real that are projective for minkowkan imaginary in 4-dim. that violate causality due beakdown of pt,and therefore the existence superluminal signals.in that universe go forward in time and backward in time is not concrete,because "past" and "future" already there are into of continuities of space-time.
Antonio carlos motta
mott.phys@bol.com.br
Antonio carlos motta
mott.phys@bol.com.br
QUOTE (Guest_carbonlife+May 12 2006, 07:23 AM)
Again, general relativity only prohibits transfer of information faster than light in a vacuum.
Really? You never know what Divine Albert has discovered. Relativity hypnotists know no limits.
Pentcho Valev
Really? You never know what Divine Albert has discovered. Relativity hypnotists know no limits.
Pentcho Valev
There are things that do in fact travel faster than light. Thr Russian Scientist, Kozyrev, did experimentation with torsion fields that determined their propagation speed to be about a billion times the speetd of light. Also, Tesla was the first American scientist to experiment with Longtidudinal electromagnetic waves that traveled faster than light speed.
Regarding the strange behavior of light within the fiber optics,IE As an old sailor man I recognize wave form and action, in an ocean wave form there always is a
faster back moving wave under the central wave bulge. due to down pressure since light passes from
particle(photon) to wave and it can at the quanta level communicate at distances and speeds exceeding light this might explain this anti Einstein development.
faster back moving wave under the central wave bulge. due to down pressure since light passes from
particle(photon) to wave and it can at the quanta level communicate at distances and speeds exceeding light this might explain this anti Einstein development.
Trying to take into consideration everything said in the column and in the posts, particularly Carbon_life's info, although I question his name (silcon based lifeform he may be). Could something like this technology be used to amplify LASER emissions. Lets say I've got a 5 kilo watt LASER (traveling north at 50 miles per hour, no no) and I bounce these waves (cause I like waves, I realize we are talking about more than just waves of light) back and forth in this or some similar type of recycling system. Could we hypothetically get amplification through wave harmonics?
One of the largest draw backs to LASER systems right now is power, for example it takes about the same volume as a bus or two worth of chemical energy to power a weapons grade zapper for missle defense. Could this tech be a first step towards finding a means to buff this technology without necessarily creating a new portable power system?
One of the largest draw backs to LASER systems right now is power, for example it takes about the same volume as a bus or two worth of chemical energy to power a weapons grade zapper for missle defense. Could this tech be a first step towards finding a means to buff this technology without necessarily creating a new portable power system?
This all sounds suspiciously like Isaac Asimov's Thiotimoline. (look it up)
[FONT=Arial]
we think that our universe the connexion of space and time( space-time ) derived of possible violation of opperatorPT and does appear two distictis torsions asymmetry that generates the curvatures of space-time " forward in time" and "backward in time".then in these curvatures the past and future alredy exist.
the universe multi dimensional is generated by two torsion disticts,and these deformation generate infinities "two torsion disticts".
we thinh that time also is generated by groups of infinities subtimes connected the subspaces correspondent.
antonio pocobi
we think that our universe the connexion of space and time( space-time ) derived of possible violation of opperatorPT and does appear two distictis torsions asymmetry that generates the curvatures of space-time " forward in time" and "backward in time".then in these curvatures the past and future alredy exist.
the universe multi dimensional is generated by two torsion disticts,and these deformation generate infinities "two torsion disticts".
we thinh that time also is generated by groups of infinities subtimes connected the subspaces correspondent.
antonio pocobi
Hey guest carbonlife, I'd like to talk about one particular ftl result of normal light phase conjugation. Reach me at ozmanusa@netscape.net
for every action there is an equal and oposite reaction. of course light goes backward, to enable pushing it forward. this paper just dramatizes basic knowledge. when you turn a light on in a room, it doesn't burn a whole in the floor, it pushes off it self, in many directions. when its' source is removed,it stops existing. when a star dies, its' light doesn't get sucked back in. it just stops moving forward.no opposite reaction, no more light. the idea that the light of a star takes a long time to travel space is lodgical, the concept that it travels backward as well is neccessary. the idea that if a star dies a million years ago and its' light is just getting here is without merit. light is energy, it needs to go backward to enable it to go forward. light is just energy, it has no life, it can't choose its' direction. it doesn't get a start, and then continue on its' own discretion.
QUOTE (Disconnect+May 11 2006, 08:55 PM)
http://www.physorg.com/news66582110.html
If that animation is accurate, what would happen if ("magically" - maybe using an LCD?) the light pulse was prevented from entering the wire as soon as it was detected leaving it?
an explosion of energy, looking for a receptor
If that animation is accurate, what would happen if ("magically" - maybe using an LCD?) the light pulse was prevented from entering the wire as soon as it was detected leaving it?
an explosion of energy, looking for a receptor
re: carbon life
there is no way to make light go faster, nor slower. light is a measure, like time. light is a real value, real according to man. it has alot of values depending on nessecity. but it a measure not unlike a yard, or foot. meter or metre. the' speed of light' is a measure. of course one could challenge its' path of energy, and make it faster or slower in an interm phase. but it will always seek its' own value. like mathmatical pie. manipulating light for any purpose other than controlling an energy source would assume your belief that light contains a carbon base. or maybe you think a carbon based entity could perform anti matter, become exclusive energy, hitch a ride , and recompose into a similar carbon based entity. an exact match would be meaningless. but the idea of hitching a ride and recomposing in a different place, is imaginitive. let alone meaningless, as it could never be brought back to compare. if you want to jetison your entity, i think it could be done in light. your destination is irreversable. your being is gone. and without returning any confirmation, your gone. but the chance that you thought it all through, knew your destiny, and calculated your means of reconstitution. you would still be dead. odds are nobody will ever come back from another time and say 'life originated from here'. can you live forever-
there is no way to make light go faster, nor slower. light is a measure, like time. light is a real value, real according to man. it has alot of values depending on nessecity. but it a measure not unlike a yard, or foot. meter or metre. the' speed of light' is a measure. of course one could challenge its' path of energy, and make it faster or slower in an interm phase. but it will always seek its' own value. like mathmatical pie. manipulating light for any purpose other than controlling an energy source would assume your belief that light contains a carbon base. or maybe you think a carbon based entity could perform anti matter, become exclusive energy, hitch a ride , and recompose into a similar carbon based entity. an exact match would be meaningless. but the idea of hitching a ride and recomposing in a different place, is imaginitive. let alone meaningless, as it could never be brought back to compare. if you want to jetison your entity, i think it could be done in light. your destination is irreversable. your being is gone. and without returning any confirmation, your gone. but the chance that you thought it all through, knew your destiny, and calculated your means of reconstitution. you would still be dead. odds are nobody will ever come back from another time and say 'life originated from here'. can you live forever-
It was explained by the physcicist that there were the leading edge and the peak of the light pulse in question which clarifies the speculation some seem to be concerned with. I believe variations in the speed actually account for the fact to be stated that the speed can be beaten the accepted speed as the speed for the basis of the equational speculation to transpire.
wjn.
wjn.
It has long been known (Newton knew) that the amount of light reflected off a thick piece of glass is dependant on the thickness .. clearly light entering 'knows' about the distant face of the slab. An optical fibre could be viewed as a thick piece of glass. It seems strange but maybe these people are the first to look at both sides of a thick piece of glass at the same time.
-C2.
-C2.
Uh, isn’t the mere fact that a pulse is detected, information? Maybe it’s just a reflection?
The reason we see light both entering and leaving is because of the devices we're using to detect it. At lower levels of observation, in other words, with more advanced technology, we can plainly see that indeed the light particle is moving steadily through from point A to point B; the only reason we can't see that now is because our technology does not allow us to. The speed of light is not a barrier but is instead a tool; one that has been very very effective for the past 100 years, but now it's obvious that we're going to have to find a new "barrier." The particles you view are only in two places at once depending on the technology you use. None of the problems with time actually occur, but only appear to occur to someone using less advanced technology. What is being shown here is a modern magical illusion created by the absence of a gaget that can click like a camera at say the speed of leptons or some other really fast thing...
just thought i'd shine my light on it,
~TJW
FW.IN.USA
just thought i'd shine my light on it,
~TJW
FW.IN.USA
we all know that light has its own proprieties that are correlated to time. the faster we push ourselves to the speed of light, the more the relative time around us will compress compared to us. if we go at the speed of light, time compresses so much that it actually stops. now, if we go faster, wont this make relative time actually go backwards? isnt this something that can be taken from this experiment and article? doesnt it make sense?
Backwards light rocks my socks.
QUOTE (MajinBu+Jun 1 2006, 08:23 PM)
we all know that light has its own proprieties that are correlated to time. the faster we push ourselves to the speed of light, the more the relative time around us will compress compared to us. if we go at the speed of light, time compresses so much that it actually stops. now, if we go faster, wont this make relative time actually go backwards? isnt this something that can be taken from this experiment and article? doesnt it make sense?
I'm not a physicist or even a physics student, just an amateur, but this is what I thought when I first read about this experiment - by breaking Einstein's speed limit on light and sending it backwards, isn't the light wave going backward in time? I seem to recall reading once a long time ago that there were theories that if we could ever figure out how to make something (like that theoretical faster-than-light particle, a tachyon) go faster than light we would in fact be sending it backward in time?
I understand at this point in the research it's not possible to encode information in the backwards light wave and that whether that could ever be possible is at the center of the debate on this board, but if it ever does become possible, through a series of backward-moving light waves or somesuch, then does it open up the possibility that at some point we could send information back in time? Isn't it that possibility that makes this experiment and this line of research so fascinating?
I'm not a physicist or even a physics student, just an amateur, but this is what I thought when I first read about this experiment - by breaking Einstein's speed limit on light and sending it backwards, isn't the light wave going backward in time? I seem to recall reading once a long time ago that there were theories that if we could ever figure out how to make something (like that theoretical faster-than-light particle, a tachyon) go faster than light we would in fact be sending it backward in time?
I understand at this point in the research it's not possible to encode information in the backwards light wave and that whether that could ever be possible is at the center of the debate on this board, but if it ever does become possible, through a series of backward-moving light waves or somesuch, then does it open up the possibility that at some point we could send information back in time? Isn't it that possibility that makes this experiment and this line of research so fascinating?
Shortdood13th asks:
"Could something like this technology be used to amplify LASER emissions. Lets say I've got a 5 kilo watt LASER (traveling north at 50 miles per hour, no no) and I bounce these waves (cause I like waves, I realize we are talking about more than just waves of light) back and forth in this or some similar type of recycling system. Could we hypothetically get amplification through wave harmonics?
"One of the largest draw backs to LASER systems right now is power, for example it takes about the same volume as a bus or two worth of chemical energy to power a weapons grade zapper for missile defense. Could this tech be a first step towards finding a means to buff this technology without necessarily creating a new portable power system?"
It's quite common to pump lasers with harmonics from another laser. That's how green laser pointers work. Harmonic pumping isn't particularly good for power applications, because you generally lose too much power in the conversion.
http://en.wikipedia.org/wiki/Laser_pointer...n_laser_pointer
There's also amplifying fiberoptic. Instead of putting booster relays along the fiberoptic, the fiberoptic glass itself is doped with a material that can lase to boost the signal, when pumped by another frequency injected into the fiberoptic as a power source.
Harmonic wizardry isn't very useful for military lasers, because the frequency of a chemical laser is poorly controlled -- a hydrogen-fluorine laser, for instance, is basically rocket fuel that can lase -- but there's frequency broadening due to the high temperature and collisions between atoms / molecules as they lase. With a high-powered chemical laser, you don't want to do anything to the beam except get it out the business end and on target before it fries the reaction chamber and adaptive optics.
For signaling applications, power isn't usually a problem. What limits your bandwidth is mainly dispersion in air. High-end fiberoptic cable is now transparent enough to wrap it around the planet without needing boosters. Transmission through air is a different story. The refractive index of air varies with frequency. Shaping a data pulse creates a range of frequency components ( sidebands ). These components travel at slightly different speeds in air, eventually degrading the pulse shape.
For long-distance space communications, e.g. from a probe orbiting Neptune, the signal beam suffers no distortion. The laser's power-handling capability is less important to bandwidth than the probe's power-GENERATING capability, which iu generally only a few hundred watts because solar is impractical that far from the Sun. The main bottleneck still isn't power, it's signal-to-noise ratio. The trick to getting over the noise is to transmit in ultra-short, high-powered data bursts which can get over the noise. Ultrashort-pulse lasers can in some cases reach peak power in the hundreds of billions of watts for a few femtoseconds. The catch is that to receive such a signal from a deep space probe, the receiver has to be outside the atmosphere, again because atmosphere degrades ultrashort data bursts.
You don't need to put a laser on rails to upshift laser frequency or power. A laser in motion doesn't generate harmonics -- all you get is a small-fractional doppler shift. You'd need a train traveling at very nearly lightspeed toward the laser, with a reflector on the front. There IS a way to do that, used to convert a regular laser beam into a high-powered X-ray laser pulse. What you do is put a fairly powerful laser pulse on a collision course with a pulsed beam from a charged-particle accelerator. The end-result is called Compton scattering -- some of the laser photons recoil from the charged particles, and get kicked into the X-ray range. The resultant X-ray beam isn't powerful enough to melt nissiles, but it is powerful enough to take holographic pictures of DNA reactions. To resolve features as small as a molecule, you need short-wavelength X-rays.
You might think that if a laser beam bounced off a reflector going the other way at nearly lightspeed, the laser frequency / energy per photon would merely double. Turns out you get a big boost from relativity -- because in the reference frame of a heavier charged particle going the other way at nearly lightspeed, the incoming laser photon is ALREADY compressed to an energetic X-ray ( by Lorentz contraction http://en.wikipedia.org/wiki/Lorentz_Contraction ) and THAT energy doubles when the photon rebounds.
There are more powerful sources of coherent X-rays, such as the Z Machine at Sandia labs, which discharges a huge bank of capacitors through a cage of thin tungsten wires. As the wires are disintegrating into plasma, they lase furiously in the X-ray band. http://en.wikipedia.org/wiki/Z_Machine
X-ray lasers have been contemplated for destroying missiles, by detonating a small nuclear weapon surrounded by metal tubes aimed at the target. Again, the tubes act as X-ray lasers in the instant they turn to hot plasma. The catch is that the laser has to be in orbit because atmosphere attenuates X-rays -- but if you set off a nuke in high enough orbit to get the drop on a sub-orbital missile, the electromagnetic pulse fries most of the electronics on the continent below http://en.wikipedia.org/wiki/Electromagnetic_pulse
Until recently, producing "bright" coherent X-rays by less extreme methods required at minimum a particle accelerator the size of a football field. However it's now possible to fit a particle accelerator on a tabletop, which shows great promise -- again using tricks of phase velocity. For a long time it was assumed [wrongly] that you could only accelerate charged particles in a high vacuum -- otherwise they'd smack into any atoms or whatever. But it turns out that particle beams can travel table-top distances through a tenuous plasma, losing only a small percentage of particles to collisions. Therein lies the secret to tabletop accelerators -- a rippling plasma can generate very high electric fields traveling at a phase velocity very close to light in a vacuum. Inject a low-energy particle beam at one end, and the particles 'surf' their way to high energy on the rippling plasma -- which oddly enough, helps focus the particle beam. A narrow beam is what you want to Compton-scatter a laser beam.
Your main question seemed to be whether tricks with refractive index can increase laser power. The short answer is, it can and it does. Researchers developing femtosecond lasers (q.v.) routinely use every trick in the book to keep the power high and the pulse short. In order to 'freeze frame' molecules 'in the act' of a chemical reaction, researchers need BOTH an ultra-short pulse, and enough total power to take the picture. Some femtosecond pulses are so powerful that their high electric fields destroy any matter they come in contact with, literally ripping off the electron shells and accelerating them to near lightspeed within under a centimeter of distance. The total energy release is fairly small -- it's the ultra-short pulse duration that concentrates such high electric fields into such a small moment in time. Femtosecond lasers have been used to delicately remove grime from centuries-old paintings, and shave microscopically thin samples of brain tissue.
Pulses of such high intensity were once thought impossible, because they'd ionize any matter they come in contact with INCLUDING THE LASER MEDIUM. The trick is to produce a longer pulse, then 'squeeze' it outside the laser, in a vacuum. Here's how they do it: a very tiny, very low-powered laser produces an ultra-short pulse of moderate field intensity, A set of mirrors and diffraction gratings then separates the pulse into frequency components, which are then reassembled by another grating into a longer pulse train that can be amplified without burning out the amplifying laser. The frequency-spreading process is then reversed, by putting the power pulse through an identical set of mirrors and gratings in reverse order. The power-pulse exits that process into a vacuum, and reassembles itself into an ultra-short power pulse on the way to the target.
The part where researchers have to use every trick in the book is to make the ultra-short pulses in the first place, so they can then be taken apart, amplified, and reassembled. See http://www.aip.org/pnu/ search term
Normally, a pulse laser is set off by a trigger laser pulse, which passes through the laser medium setting off a cascade reaction. That's not fast enough for a femtosecond laser, because it takes too longer than femtoseconds for a trigger pulse to cross the laser. Light travels less than three tenths of a micron per femtosecond. You need to set up the pulse in advance ( "one, two, three, GO" ), so that all the atoms kick in their energy at exactly the right time. In a normal laser, the lasing atoms have plenty of time to get in synch, because the laser pulse builds up in the cavity over thousands or millions of oscillations. In a femtosecond laser, the pulse may be over and gone in as little as one wavelength, and the leading edge of the pulse is so strong it would trigger atoms to lase prematurely. So tricks of phase velocity are used to create the "One, two, three GO" effect", though of course it's more complicated than that. Harmonic effects can be useful in the pumping sequence, but you generally don't want harmonics in the output beam, because the higher the frequency, the greater the energy losses within the laser cavity, which show up as heat that has to be gotten rid of / limiis power.
Tricks with phase velocity and refractive index are just ONE tool of many. For example, the easiest way ( in principle ) to turn electrical power into laser power is to send electrons through periodic structures, so that the electron automatically interacts with periodic fields, and so that the structural automatically selects for a precise wavelength. The structural periodicity required is in the nanometer range, achievable by either nano-fabrication or by some sort of self-organizing system.
Tricks with refractive index and phase velocity get a lot easier if you can 'draw' 3-D interference patterns inside an optronic crystal -- and erase / rewrite then at will. Optically programmable crystals are a challenge in materials science / solid state physics, The behavior of interfering light waves has been thoroughly studied for over a century -- the first really good interferometer able to verify the constancy of the speed of light was built in 1886 for the Michelson-Morley Experiment. The hard part is developing optically programmable materials that do what engineers tell them.
Another promising direction in laser technology is quantum confinement. Light amplification by stimulated emission of radiation is fundamentally a quantum-mechanical process. Buckytubes ( q.v.) are turning out to have remarkable electronic and optical properties, because electrons are constrained to move in essentially oine dimension along the axis of the tube. Quantum dots don't allow an electron to move at all, and have remarkable ability to resonate with light / participate in quantum entanglement. Quantum holes in ultrathin metal sheets can trap and control light to an amazing degree. These small structures act in essence like quantum antenna arrays for light. The quantum physics involved isn't new, but it takes experimental proof-of-concept to direct research funding toward fabrication techniques for such devices. Near-total control of light is the Next Big Thing in computing, because photons light can do what electrons cannot. Light can travel through through a deeply layered chip whild generating almost no heat. Photons of light are inherently cooperative -- they don't repel each other as electrons do. Coherent light can perform complex computations ( Fourier transforms ) while traveling through a vacuum, and so on.
Researchers are even starting to have success with matter lasers -- coherent streams of atoms which can create interference patterns over distances the size of single atoms. In principle, layered geometric patterns could be 'sprayed onto' a chip by matter lasers, creating antenna structures and waveguides covering the entire range from coherent infrared light to coherent X-ray.
The problem is not lack of a 'new physics'. The physics is already on the horizon -- it just needs enough talent and enough enterprise to turn the physics into engineering, and THEN we'll see some _2001_ stuff that'll have people slack-jawed with wonder. Ya just gotta approach it the right way. Einstein's way ( the most successful to date ) was to view nature as a tapestry, and realize that we're only seeing a few threads in the near distance. By following a single thread ( the invariance of the speed of light ), Einstein arrived at some mind-boggling insights -- and because he'd really STUDIED physics, saw that they 'clicked' with other natural phenomena. An amazing thing about nature is how it all fits together -- that's the Big Clue. Seeing how physics fits together is half the fun, but ya gotta look at the tapestry, not just one knot in one thread.
--
"The trick is to find the right angle." -- Pythagoras.
"Could something like this technology be used to amplify LASER emissions. Lets say I've got a 5 kilo watt LASER (traveling north at 50 miles per hour, no no) and I bounce these waves (cause I like waves, I realize we are talking about more than just waves of light) back and forth in this or some similar type of recycling system. Could we hypothetically get amplification through wave harmonics?
"One of the largest draw backs to LASER systems right now is power, for example it takes about the same volume as a bus or two worth of chemical energy to power a weapons grade zapper for missile defense. Could this tech be a first step towards finding a means to buff this technology without necessarily creating a new portable power system?"
It's quite common to pump lasers with harmonics from another laser. That's how green laser pointers work. Harmonic pumping isn't particularly good for power applications, because you generally lose too much power in the conversion.
http://en.wikipedia.org/wiki/Laser_pointer...n_laser_pointer
There's also amplifying fiberoptic. Instead of putting booster relays along the fiberoptic, the fiberoptic glass itself is doped with a material that can lase to boost the signal, when pumped by another frequency injected into the fiberoptic as a power source.
Harmonic wizardry isn't very useful for military lasers, because the frequency of a chemical laser is poorly controlled -- a hydrogen-fluorine laser, for instance, is basically rocket fuel that can lase -- but there's frequency broadening due to the high temperature and collisions between atoms / molecules as they lase. With a high-powered chemical laser, you don't want to do anything to the beam except get it out the business end and on target before it fries the reaction chamber and adaptive optics.
For signaling applications, power isn't usually a problem. What limits your bandwidth is mainly dispersion in air. High-end fiberoptic cable is now transparent enough to wrap it around the planet without needing boosters. Transmission through air is a different story. The refractive index of air varies with frequency. Shaping a data pulse creates a range of frequency components ( sidebands ). These components travel at slightly different speeds in air, eventually degrading the pulse shape.
For long-distance space communications, e.g. from a probe orbiting Neptune, the signal beam suffers no distortion. The laser's power-handling capability is less important to bandwidth than the probe's power-GENERATING capability, which iu generally only a few hundred watts because solar is impractical that far from the Sun. The main bottleneck still isn't power, it's signal-to-noise ratio. The trick to getting over the noise is to transmit in ultra-short, high-powered data bursts which can get over the noise. Ultrashort-pulse lasers can in some cases reach peak power in the hundreds of billions of watts for a few femtoseconds. The catch is that to receive such a signal from a deep space probe, the receiver has to be outside the atmosphere, again because atmosphere degrades ultrashort data bursts.
You don't need to put a laser on rails to upshift laser frequency or power. A laser in motion doesn't generate harmonics -- all you get is a small-fractional doppler shift. You'd need a train traveling at very nearly lightspeed toward the laser, with a reflector on the front. There IS a way to do that, used to convert a regular laser beam into a high-powered X-ray laser pulse. What you do is put a fairly powerful laser pulse on a collision course with a pulsed beam from a charged-particle accelerator. The end-result is called Compton scattering -- some of the laser photons recoil from the charged particles, and get kicked into the X-ray range. The resultant X-ray beam isn't powerful enough to melt nissiles, but it is powerful enough to take holographic pictures of DNA reactions. To resolve features as small as a molecule, you need short-wavelength X-rays.
You might think that if a laser beam bounced off a reflector going the other way at nearly lightspeed, the laser frequency / energy per photon would merely double. Turns out you get a big boost from relativity -- because in the reference frame of a heavier charged particle going the other way at nearly lightspeed, the incoming laser photon is ALREADY compressed to an energetic X-ray ( by Lorentz contraction http://en.wikipedia.org/wiki/Lorentz_Contraction ) and THAT energy doubles when the photon rebounds.
There are more powerful sources of coherent X-rays, such as the Z Machine at Sandia labs, which discharges a huge bank of capacitors through a cage of thin tungsten wires. As the wires are disintegrating into plasma, they lase furiously in the X-ray band. http://en.wikipedia.org/wiki/Z_Machine
X-ray lasers have been contemplated for destroying missiles, by detonating a small nuclear weapon surrounded by metal tubes aimed at the target. Again, the tubes act as X-ray lasers in the instant they turn to hot plasma. The catch is that the laser has to be in orbit because atmosphere attenuates X-rays -- but if you set off a nuke in high enough orbit to get the drop on a sub-orbital missile, the electromagnetic pulse fries most of the electronics on the continent below http://en.wikipedia.org/wiki/Electromagnetic_pulse
Until recently, producing "bright" coherent X-rays by less extreme methods required at minimum a particle accelerator the size of a football field. However it's now possible to fit a particle accelerator on a tabletop, which shows great promise -- again using tricks of phase velocity. For a long time it was assumed [wrongly] that you could only accelerate charged particles in a high vacuum -- otherwise they'd smack into any atoms or whatever. But it turns out that particle beams can travel table-top distances through a tenuous plasma, losing only a small percentage of particles to collisions. Therein lies the secret to tabletop accelerators -- a rippling plasma can generate very high electric fields traveling at a phase velocity very close to light in a vacuum. Inject a low-energy particle beam at one end, and the particles 'surf' their way to high energy on the rippling plasma -- which oddly enough, helps focus the particle beam. A narrow beam is what you want to Compton-scatter a laser beam.
Your main question seemed to be whether tricks with refractive index can increase laser power. The short answer is, it can and it does. Researchers developing femtosecond lasers (q.v.) routinely use every trick in the book to keep the power high and the pulse short. In order to 'freeze frame' molecules 'in the act' of a chemical reaction, researchers need BOTH an ultra-short pulse, and enough total power to take the picture. Some femtosecond pulses are so powerful that their high electric fields destroy any matter they come in contact with, literally ripping off the electron shells and accelerating them to near lightspeed within under a centimeter of distance. The total energy release is fairly small -- it's the ultra-short pulse duration that concentrates such high electric fields into such a small moment in time. Femtosecond lasers have been used to delicately remove grime from centuries-old paintings, and shave microscopically thin samples of brain tissue.
Pulses of such high intensity were once thought impossible, because they'd ionize any matter they come in contact with INCLUDING THE LASER MEDIUM. The trick is to produce a longer pulse, then 'squeeze' it outside the laser, in a vacuum. Here's how they do it: a very tiny, very low-powered laser produces an ultra-short pulse of moderate field intensity, A set of mirrors and diffraction gratings then separates the pulse into frequency components, which are then reassembled by another grating into a longer pulse train that can be amplified without burning out the amplifying laser. The frequency-spreading process is then reversed, by putting the power pulse through an identical set of mirrors and gratings in reverse order. The power-pulse exits that process into a vacuum, and reassembles itself into an ultra-short power pulse on the way to the target.
The part where researchers have to use every trick in the book is to make the ultra-short pulses in the first place, so they can then be taken apart, amplified, and reassembled. See http://www.aip.org/pnu/ search term
Normally, a pulse laser is set off by a trigger laser pulse, which passes through the laser medium setting off a cascade reaction. That's not fast enough for a femtosecond laser, because it takes too longer than femtoseconds for a trigger pulse to cross the laser. Light travels less than three tenths of a micron per femtosecond. You need to set up the pulse in advance ( "one, two, three, GO" ), so that all the atoms kick in their energy at exactly the right time. In a normal laser, the lasing atoms have plenty of time to get in synch, because the laser pulse builds up in the cavity over thousands or millions of oscillations. In a femtosecond laser, the pulse may be over and gone in as little as one wavelength, and the leading edge of the pulse is so strong it would trigger atoms to lase prematurely. So tricks of phase velocity are used to create the "One, two, three GO" effect", though of course it's more complicated than that. Harmonic effects can be useful in the pumping sequence, but you generally don't want harmonics in the output beam, because the higher the frequency, the greater the energy losses within the laser cavity, which show up as heat that has to be gotten rid of / limiis power.
Tricks with phase velocity and refractive index are just ONE tool of many. For example, the easiest way ( in principle ) to turn electrical power into laser power is to send electrons through periodic structures, so that the electron automatically interacts with periodic fields, and so that the structural automatically selects for a precise wavelength. The structural periodicity required is in the nanometer range, achievable by either nano-fabrication or by some sort of self-organizing system.
Tricks with refractive index and phase velocity get a lot easier if you can 'draw' 3-D interference patterns inside an optronic crystal -- and erase / rewrite then at will. Optically programmable crystals are a challenge in materials science / solid state physics, The behavior of interfering light waves has been thoroughly studied for over a century -- the first really good interferometer able to verify the constancy of the speed of light was built in 1886 for the Michelson-Morley Experiment. The hard part is developing optically programmable materials that do what engineers tell them.
Another promising direction in laser technology is quantum confinement. Light amplification by stimulated emission of radiation is fundamentally a quantum-mechanical process. Buckytubes ( q.v.) are turning out to have remarkable electronic and optical properties, because electrons are constrained to move in essentially oine dimension along the axis of the tube. Quantum dots don't allow an electron to move at all, and have remarkable ability to resonate with light / participate in quantum entanglement. Quantum holes in ultrathin metal sheets can trap and control light to an amazing degree. These small structures act in essence like quantum antenna arrays for light. The quantum physics involved isn't new, but it takes experimental proof-of-concept to direct research funding toward fabrication techniques for such devices. Near-total control of light is the Next Big Thing in computing, because photons light can do what electrons cannot. Light can travel through through a deeply layered chip whild generating almost no heat. Photons of light are inherently cooperative -- they don't repel each other as electrons do. Coherent light can perform complex computations ( Fourier transforms ) while traveling through a vacuum, and so on.
Researchers are even starting to have success with matter lasers -- coherent streams of atoms which can create interference patterns over distances the size of single atoms. In principle, layered geometric patterns could be 'sprayed onto' a chip by matter lasers, creating antenna structures and waveguides covering the entire range from coherent infrared light to coherent X-ray.
The problem is not lack of a 'new physics'. The physics is already on the horizon -- it just needs enough talent and enough enterprise to turn the physics into engineering, and THEN we'll see some _2001_ stuff that'll have people slack-jawed with wonder. Ya just gotta approach it the right way. Einstein's way ( the most successful to date ) was to view nature as a tapestry, and realize that we're only seeing a few threads in the near distance. By following a single thread ( the invariance of the speed of light ), Einstein arrived at some mind-boggling insights -- and because he'd really STUDIED physics, saw that they 'clicked' with other natural phenomena. An amazing thing about nature is how it all fits together -- that's the Big Clue. Seeing how physics fits together is half the fun, but ya gotta look at the tapestry, not just one knot in one thread.
--
"The trick is to find the right angle." -- Pythagoras.
Hey Carbon, i really enjoy your explanations, How about centrifugal force. You know like a spin drier. I was thinking in form of entropy. My idea is this that an accelerating spin drier presses the clothes towards its wall because of their need to leave in a (geodesic?) straight line which the wall stops. But what about when the drier has reached a constant revolving speed, what keeps them pressed to the wall? Would it be that the straight line is the most cost effective direction for the clothes? I know it's called inertia, but heck. That doesn't tell me a thing. If it so then there are no specific direction where the clothes wanna go, kind of. except away from that f***ng spin drier of course :)
I mean a black spinning hole or star distorts spacetime right, it drags and twists it around itself, and creates an enormous gravitational force, but a spin drier?
It gives me a head ache..
I mean a black spinning hole or star distorts spacetime right, it drags and twists it around itself, and creates an enormous gravitational force, but a spin drier?
It gives me a head ache..
i have an idea which could make the light double the speed at the point of no view..,the motorway was a great view to a brilliant idea!
why think light is faster goin jst backwards?.., light moves in all directions.
What frequency was needed for the pulse to ride on in order for it to move backward?
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