Do you have adblock enabled?
If you can read this, either the style sheet didn't load or you have an older browser that doesn't support style sheets. Try clearing your browser cache and refreshing the page.

(PhysOrg.com)   Scientists create light in a vacuum. That sucks, but in a good way   (physorg.com) divider line 47
    More: Cool, virtual particles, scientists create, speed of light, Nobel Prize in Physics, short circuit, old quantum theory, vacuum, kinetic energy  
•       •       •

4274 clicks; posted to Geek » on 17 Nov 2011 at 9:40 AM (3 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



47 Comments   (+0 »)
   

Archived thread
 
2011-11-17 09:04:48 AM  
It's like a rainbow in the dark!
 
2011-11-17 09:19:08 AM  

Jake Havechek: It's like a rainbow in the dark!


Damn,that would have made a much better headline
 
2011-11-17 09:52:06 AM  
I c what you did there
 
2011-11-17 10:02:02 AM  
Meh, I did this 2 years ago with my Dyson.
 
2011-11-17 10:04:12 AM  
img534.imageshack.us
You mean this SQUID device?

/hot like a 16-year-old girl taking a shower
 
2011-11-17 10:06:48 AM  
Pimp my dyson.
 
2011-11-17 10:31:05 AM  
FTA: "Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy."

I can't be the only one who read this and thought, "Holy crap, the ancestor to the food replicator!"
 
2011-11-17 10:37:26 AM  
Isn't this old news? I thought they had observed something similar with x-rays in a vacuum?
 
2011-11-17 10:46:50 AM  
I thought scientists didn't believe in creation.
 
2011-11-17 10:50:13 AM  

meat0918: Isn't this old news? I thought they had observed something similar with x-rays in a vacuum?


This is very different from that. In an x-ray tube, the high energy photon is released when a charged metallic ion travels from one end of the tube to the other and slams into another metal. What these scientists have done is shown that you can detect photons that don't come from any interacting matter.
 
2011-11-17 11:03:09 AM  

Peki: FTA: "Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy."

I can't be the only one who read this and thought, "Holy crap, the ancestor to the food replicator!"


Yep, yep that was my first thought as well.

"Tea, Earl Grey, Hot."
 
2011-11-17 11:18:58 AM  
How much vacuum are we talking about here? Isn't the space between atoms full of vacuum, too? Does this blip/blip kind of stuff that always happening happen more in an extremely vacuousness environment? Is this dark matter? I need to get a good book about this. Any suggestions?
 
2011-11-17 11:22:40 AM  

Fizpez: Peki: FTA: "Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy."

I can't be the only one who read this and thought, "Holy crap, the ancestor to the food replicator!"

Yep, yep that was my first thought as well.

"Tea, Earl Grey, Hot."


nerd voice

Actually replicator technology is based on the transporter. Patterns are stored in the computers memory and reassembled using stored matter in the ships systems. It is theoretically possible to do the same thing with people but a living being is so complex that the federation does not have the memory to do so. It is theoretically possible for the federation to build a space station sized replicator that will be able to scan an entire ship and crew and create a clone of it.

/nerd voice
 
2011-11-17 11:27:19 AM  

Fizpez: Peki: FTA: "Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy."

I can't be the only one who read this and thought, "Holy crap, the ancestor to the food replicator!"

Yep, yep that was my first thought as well.

"Tea, Earl Grey, Hot."


It shouldn't have been your first thought, because replicators don't make particles out of thin air, they rearrange already existing atoms from waste materials like a near perfect recycling system.

It's closer to the ZPMs from Stargate which create usable power from the zero point energy in a vacuum.
 
2011-11-17 11:33:15 AM  
We can figure out stuff like this, but crumpled up paper is still our best invention for wiping our asses.

Ugh.
 
2011-11-17 11:34:41 AM  

LrdPhoenix: Fizpez: Peki: FTA: "Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy."

I can't be the only one who read this and thought, "Holy crap, the ancestor to the food replicator!"

Yep, yep that was my first thought as well.

"Tea, Earl Grey, Hot."

It shouldn't have been your first thought, because replicators don't make particles out of thin air, they rearrange already existing atoms from waste materials like a near perfect recycling system.

It's closer to the ZPMs from Stargate which create usable power from the zero point energy in a vacuum.


Whenever they said Zed PM, it always reminded me of this guy

images.wikia.com
 
2011-11-17 11:49:25 AM  

sxacho: How much vacuum are we talking about here? Isn't the space between atoms full of vacuum, too? Does this blip/blip kind of stuff that always happening happen more in an extremely vacuousness environment? Is this dark matter? I need to get a good book about this. Any suggestions?


It happens everywhere, all the time. It's happening in your colon right now. Vacuum energy/zero point energy is the ground state of the universe, the lowest energy possible at any point at any time, which is non zero. These virtual particles pop into existence spontaneously in pairs, such as an electron and positron, and then collide annihilating each other. Well, it's more like the possibility of a pair of new particles being in this space comes into existence and then ceases to be, but they can become real particles if you can keep them separate from each other. That's how that whole Hawking radiation thing works, a pair of virtual particles come into being near the edge of a black hole, one falls in and the other flies off as a real particle. It's always in pairs, you can create a particle (and thus matter and energy) from nothing so long as you also create an equal antiparticle which keeps the balance.

However, if you want to actually detect it happening, then you have to remove all the external energy and particles flying around, which requires a good vacuum.

Or something like that.
 
2011-11-17 11:51:19 AM  
So...could this be the first step on the road to the fabled infinite energy of zero-point energy?

("Zero-point" energy of course not being entirely accurate, since it simply describes the ground state of a thermodynamic system. You know what I mean.)
 
2011-11-17 11:52:10 AM  

tgregory: We can figure out stuff like this, but crumpled up paper is still our best invention for wiping our asses.

Ugh.


Bidets & cotonelle

//what 3rd world country do you live in? I'm surprised you have the internets

///I feel sorry for your ass
////hole
 
2011-11-17 11:55:16 AM  

sxacho: How much vacuum are we talking about here? Isn't the space between atoms full of vacuum, too? Does this blip/blip kind of stuff that always happening happen more in an extremely vacuousness environment? Is this dark matter? I need to get a good book about this. Any suggestions?

Fabric of the Cosmos

by Brian Greene
 
2011-11-17 11:57:50 AM  

LrdPhoenix: It happens everywhere, all the time. It's happening in your colon right now. These virtual particles... collide annihilating each other


And that energy release is why you fart.
 
2011-11-17 12:05:46 PM  

LrdPhoenix: sxacho: How much vacuum are we talking about here? Isn't the space between atoms full of vacuum, too? Does this blip/blip kind of stuff that always happening happen more in an extremely vacuousness environment? Is this dark matter? I need to get a good book about this. Any suggestions?

It happens everywhere, all the time. It's happening in your colon right now. Vacuum energy/zero point energy is the ground state of the universe, the lowest energy possible at any point at any time, which is non zero. These virtual particles pop into existence spontaneously in pairs, such as an electron and positron, and then collide annihilating each other. Well, it's more like the possibility of a pair of new particles being in this space comes into existence and then ceases to be, but they can become real particles if you can keep them separate from each other. That's how that whole Hawking radiation thing works, a pair of virtual particles come into being near the edge of a black hole, one falls in and the other flies off as a real particle. It's always in pairs, you can create a particle (and thus matter and energy) from nothing so long as you also create an equal antiparticle which keeps the balance.

However, if you want to actually detect it happening, then you have to remove all the external energy and particles flying around, which requires a good vacuum.

Or something like that.


Oh, also, since they created photons, there are no real antiphotons, so they would have created two photons with equal energy and opposite waveforms. So if the waveform of the first photon could be modeled by sin(x), then the waveform of the second photon would be sin(-x), which would cancel each other out on collision.
 
2011-11-17 12:07:22 PM  
Skinner!!
 
2011-11-17 12:08:27 PM  
Time in a bottle still elusive.
 
2011-11-17 12:24:34 PM  

carrion_luggage: Time in a bottle still elusive.


That's the first thing that I'd like to do.
 
2011-11-17 12:54:33 PM  
Zero Point Energy generator, here we come.
 
2011-11-17 01:00:51 PM  

Wenchmaster: sxacho: How much vacuum are we talking about here? Isn't the space between atoms full of vacuum, too? Does this blip/blip kind of stuff that always happening happen more in an extremely vacuousness environment? Is this dark matter? I need to get a good book about this. Any suggestions?

Fabric of the Cosmos by Brian Greene


Is that the twerpy guy on that Nova show? They should have really gotten a better host. But thanks.
 
2011-11-17 01:16:38 PM  

LrdPhoenix: So if the waveform of the first photon could be modeled by sin(x), then the waveform of the second photon would be sin(-x), which would cancel each other out on collision.


Wouldn't it be csc(x)? sin(-x) = -sin(x), right?

It's been like... a farking decade... so I could very well be wrong as all hell.

/I'm almost definitely wrong as all hell.
 
2011-11-17 01:53:53 PM  

BeesNuts: LrdPhoenix: So if the waveform of the first photon could be modeled by sin(x), then the waveform of the second photon would be sin(-x), which would cancel each other out on collision.

Wouldn't it be csc(x)? sin(-x) = -sin(x), right?

It's been like... a farking decade... so I could very well be wrong as all hell.

/I'm almost definitely wrong as all hell.


sin(-x) is equal to -sin(x). Not even sure you can have a cosecant energy waveform. All I know is that sin(x) and sin(-x) (or -sin(x)) are inverses, when y = 1 on one, then y = -1 on the other. If you add up all the y values for both they equal 0.
 
2011-11-17 02:59:29 PM  
Why the fark do people think stuff like this can create free energy? I just don't get how "We put energy into the system and got photons out" turns into "OMG conservation of energy is wrong!"

Quantum mechanics does not make crappy sci-fi true, and experiments that validate quantum mechanics do not mean you'll be flying across galaxies and farking green alien chicks. Dumbasses.
 
2011-11-17 03:34:39 PM  

Professor Science: Why the fark do people think stuff like this can create free energy? I just don't get how "We put energy into the system and got photons out" turns into "OMG conservation of energy is wrong!"

Quantum mechanics does not make crappy sci-fi true, and experiments that validate quantum mechanics do not mean you'll be flying across galaxies and farking green alien chicks. Dumbasses.


Well shiat if you can think of a better way to fark green alien chicks I'm all ears.
 
2011-11-17 03:41:08 PM  

LrdPhoenix: BeesNuts: LrdPhoenix: So if the waveform of the first photon could be modeled by sin(x), then the waveform of the second photon would be sin(-x), which would cancel each other out on collision.

Wouldn't it be csc(x)? sin(-x) = -sin(x), right?

It's been like... a farking decade... so I could very well be wrong as all hell.

/I'm almost definitely wrong as all hell.

sin(-x) is equal to -sin(x). Not even sure you can have a cosecant energy waveform. All I know is that sin(x) and sin(-x) (or -sin(x)) are inverses, when y = 1 on one, then y = -1 on the other. If you add up all the y values for both they equal 0.


I just drew it out and I'm an idiot. Sin(pi) = 1, Sin(-pi) = -1... Herpadurr.

For some reason I was hung up on the whole definitions thing.
Sin(x) = 1/Csc(x)
.`.
i42.tinypic.com

Reciprocal != Inverse. I need to go back to high school or something.
 
2011-11-17 03:41:11 PM  

sxacho: Is that the twerpy guy on that Nova show? They should have really gotten a better host. But thanks.


Yeah, that's him. Part of why he seems twerpy is because he's trying desperately to dumb down fairly complex ideas for a TV audience. The other part of why he seems twerpy is because he's not a particularly good speaker (IMO). I've found the science is usually better presented in his writing.

Alternately, you could email Bad Astronomer and ask him for some other reading on the subject.
 
2011-11-17 03:47:57 PM  

Professor Science: Why the fark do people think stuff like this can create free energy? I just don't get how "We put energy into the system and got photons out" turns into "OMG conservation of energy is wrong!"

Quantum mechanics does not make crappy sci-fi true, and experiments that validate quantum mechanics do not mean you'll be flying across galaxies and farking green alien chicks. Dumbasses.


Interestingly the ability to "create" paired photons DOES make for some cool 'sci-fi' fantasties. If these particles can be entangled and separated, altering the properties of the one will instantaneously alter the properties of the other across any arbitrary distance. We're talking centuries of work towards that specific goal, and several thousand steps between here and there, but quantum mechanics produces some really confusing shiat. I can understand completely that people see something that apparently violates every physical principle they have ever been taught and extrapolate that to the very definitive conservation of mass and energy. It's kind of dumb, but meh. People like to get excited about things they don't entirely understand, myself included. I prefer it over apathy, really.
 
2011-11-17 04:09:43 PM  

tgregory: We can figure out stuff like this, but crumpled up paper is still our best invention for wiping our asses.

Ugh.



He doesn't know how to use the three seashells! Hahahahahah!
 
2011-11-17 04:26:09 PM  

BeesNuts: Professor Science: Why the fark do people think stuff like this can create free energy? I just don't get how "We put energy into the system and got photons out" turns into "OMG conservation of energy is wrong!"

Quantum mechanics does not make crappy sci-fi true, and experiments that validate quantum mechanics do not mean you'll be flying across galaxies and farking green alien chicks. Dumbasses.

Interestingly the ability to "create" paired photons DOES make for some cool 'sci-fi' fantasties. If these particles can be entangled and separated, altering the properties of the one will instantaneously alter the properties of the other across any arbitrary distance. We're talking centuries of work towards that specific goal, and several thousand steps between here and there, but quantum mechanics produces some really confusing shiat. I can understand completely that people see something that apparently violates every physical principle they have ever been taught and extrapolate that to the very definitive conservation of mass and energy. It's kind of dumb, but meh. People like to get excited about things they don't entirely understand, myself included. I prefer it over apathy, really.


Extracting ZP energy may not be a violation of thermodynamics, if you consider that those particles may come from a different universe or dimension.
 
2011-11-17 04:28:03 PM  

Shazam999: BeesNuts: Professor Science: Why the fark do people think stuff like this can create free energy? I just don't get how "We put energy into the system and got photons out" turns into "OMG conservation of energy is wrong!"

Quantum mechanics does not make crappy sci-fi true, and experiments that validate quantum mechanics do not mean you'll be flying across galaxies and farking green alien chicks. Dumbasses.

Interestingly the ability to "create" paired photons DOES make for some cool 'sci-fi' fantasties. If these particles can be entangled and separated, altering the properties of the one will instantaneously alter the properties of the other across any arbitrary distance. We're talking centuries of work towards that specific goal, and several thousand steps between here and there, but quantum mechanics produces some really confusing shiat. I can understand completely that people see something that apparently violates every physical principle they have ever been taught and extrapolate that to the very definitive conservation of mass and energy. It's kind of dumb, but meh. People like to get excited about things they don't entirely understand, myself included. I prefer it over apathy, really.

Extracting ZP energy may not be a violation of thermodynamics, if you consider that those particles may come from a different universe or dimension.


My personal favorite idea is that if we ever harness zero-point energy it will be because we're exploiting a flaw in the simulation. No alternate universes or anything like that, just good old wallhacking.
 
2011-11-17 04:43:36 PM  

Jake Havechek: It's like a rainbow in the dark!


Done in one. Pack it up, we're good here.
 
2011-11-17 04:46:23 PM  

Shazam999: Extracting ZP energy may not be a violation of thermodynamics, if you consider that those particles may come from a different universe or dimension


images3.wikia.nocookie.net
 
2011-11-17 05:07:48 PM  

BeesNuts: Interestingly the ability to "create" paired photons DOES make for some cool 'sci-fi' fantasties. If these particles can be entangled and separated, altering the properties of the one will instantaneously alter the properties of the other across any arbitrary distance. We're talking centuries of work towards that specific goal, and several thousand steps between here and there, but quantum mechanics produces some really confusing shiat.


There are a couple of things wrong with this. First, we can already create entangled photon pairs. The current technology for it is kinda clumsy, but it's already good enough for encrypting bank-to-bank communications in some markets.

Second, entanglement does not work that way! You cannot send information via entangled particles; you can only create the same random information in separate locations. The sci-fi instant communication thing is pure -fi, and that's not a matter of technology -- it's a fundamental limitation of the physics involved. I'm not as upset about that misconception, though, since it's much more subtle than the zero point energy thing. The fact that it would violate causality and allow you to send information back in time should be a pretty big tip-off, but recognizing that requires at least a passing familiarity with relativity.
 
2011-11-17 06:13:40 PM  
"SQUID", you say?

img.photobucket.com
 
2011-11-17 09:02:13 PM  
Lord Dimwit: So...could this be the first step on the road to the fabled infinite energy of zero-point energy?

Bob Forward designed a workable (but inefficient and ridiculously expensive) casimir battery decades ago. It operates entirely on proven principles and extracts the same energy as this experiment. It does not, however, natively produce microwave radiation.


Incidentally. A method like this could; conceivably produce much more energy than it uses. There's no reason this needs to be a violation of thermodynamics -- for instance, there's a good chance that if the particles do not mutually cancel, then the local expansion of space-time is reduced. Very, very slightly. You can think of this as a (hopefully) non-self-supporting 'burning' of space-time potentiality, or the conversion of dark energy to photons.

However, there is absolutely no reason to assume that there's any failure to conserve energy here. Since the dark energy presumed involved can't currently be measured . . . no matter how much EM energy is released, you don't know what the net is. No reason to assume it's something weird.

BUT there's also no reason to believe that thermodynamics applies strictly to the universe as a whole. The notion that the universe is a closed system is a semantic or rhetorical one. Limits on knowledge mean you can never determine if a system is closed if you're inside it. If you're not inside it, and you can determine that it's really closed, that observation would necessarily alter that system, and hence it's not really closed.

The short version: Don't get too wankery about thermodynamics.
 
2011-11-17 11:51:36 PM  

RandomAxe: Bob Forward designed a workable (but inefficient and ridiculously expensive) casimir battery decades ago. It operates entirely on proven principles and extracts the same energy as this experiment.


It's generous (and possibly misleading) to describe that Casimir battery as "extracting" energy, and it's definitely misleading to describe the experiment in TFA as doing so Given all the silliness that floats about this subject matter, one should be careful to mention that the Casimir effect creates a conservative force -- i.e. once the plates in Forward's battery pull themselves together and release energy, you have to put just as much energy back into it to pull them apart again. You can't generate energy with it any more than you can generate energy with a compressed spring. It releases a little bit of energy once, then it's done. If you want to get anything else out, you have to put it in first.

Incidentally. A method like this could; conceivably produce much more energy than it uses. There's no reason this needs to be a violation of thermodynamics -- for instance, there's a good chance that if the particles do not mutually cancel, then the local expansion of space-time is reduced. Very, very slightly. You can think of this as a (hopefully) non-self-supporting 'burning' of space-time potentiality, or the conversion of dark energy to photons.

There's little to no reason to assume that electromagnetic vacuum energy has anything to do with cosmological dark energy. In fact, if you do assume that, you can immediately calculate that the density of dark energy is about 10120 times larger than the observed value, which provides plenty of reason to think that they're quite unrelated.

However, there is absolutely no reason to assume that there's any failure to conserve energy here. Since the dark energy presumed involved can't currently be measured . . . no matter how much EM energy is released, you don't know what the net is. No reason to assume it's something weird.

I'm not sure which "here" you're referring to. In the experiment described by TFA, there's nothing to account for -- they put energy into the system via a microwave-frequency magnetic field applied to the SQUID, and observed lower-frequency microwaves coming out the SQUID-terminated transmission line. No energy was released from anything. The effect is pretty much equivalent to parametric downconversion, but the frequency distribution of output photons apparently can be traced to the effect of vacuum fluctuations. If you take the original inspiration of an oscillating mirror, then the equations predict a drag force on the mirror which removes exactly as much kinetic energy from it as is released in the photons.

Also, why do you claim the "dark energy" can't be measured? We've measured the cosmological dark energy (which is irrelevant to the experiment), and we've measured (at least the long-wavelength parts of) the electromagnetic vacuum energy. What's more, we can calculate that EM vacuum energy based on the boundary conditions of the region of vacuum we're interested in, and show that it never gives up energy that you don't have to pay back. There's no need to invoke thermodynamics at all; conservation of energy is right there in the quantum field theory.
 
2011-11-18 01:55:51 AM  

Professor Science: RandomAxe: Bob Forward designed a workable (but inefficient and ridiculously expensive) casimir battery decades ago. It operates entirely on proven principles and extracts the same energy as this experiment.

It's generous (and possibly misleading) to describe that Casimir battery as "extracting" energy, and it's definitely misleading to describe the experiment in TFA as doing so Given all the silliness that floats about this subject matter, one should be careful to mention that the Casimir effect creates a conservative force -- i.e. once the plates in Forward's battery pull themselves together and release energy, you have to put just as much energy back into it to pull them apart again. You can't generate energy with it any more than you can generate energy with a compressed spring. It releases a little bit of energy once, then it's done. If you want to get anything else out, you have to put it in first.

Incidentally. A method like this could; conceivably produce much more energy than it uses. There's no reason this needs to be a violation of thermodynamics -- for instance, there's a good chance that if the particles do not mutually cancel, then the local expansion of space-time is reduced. Very, very slightly. You can think of this as a (hopefully) non-self-supporting 'burning' of space-time potentiality, or the conversion of dark energy to photons.

There's little to no reason to assume that electromagnetic vacuum energy has anything to do with cosmological dark energy. In fact, if you do assume that, you can immediately calculate that the density of dark energy is about 10120 times larger than the observed value, which provides plenty of reason to think that they're quite unrelated.

However, there is absolutely no reason to assume that there's any failure to conserve energy here. Since the dark energy presumed involved can't currently be measured . . . no matter how much EM energy is released, you don't know what the net is. No reason to assume it's something weird.

I'm not sure which "here" you're referring to. In the experiment described by TFA, there's nothing to account for -- they put energy into the system via a microwave-frequency magnetic field applied to the SQUID, and observed lower-frequency microwaves coming out the SQUID-terminated transmission line. No energy was released from anything. The effect is pretty much equivalent to parametric downconversion, but the frequency distribution of output photons apparently can be traced to the effect of vacuum fluctuations. If you take the original inspiration of an oscillating mirror, then the equations predict a drag force on the mirror which removes exactly as much kinetic energy from it as is released in the photons.

Also, why do you claim the "dark energy" can't be measured? We've measured the cosmological dark energy (which is irrelevant to the experiment), and we've measured (at least the long-wavelength parts of) the electromagnetic vacuum energy. What's more, we can calculate that EM vacuum energy based on the boundary conditions of the region of vacuum we're interested in, and show that it never gives up energy that you don't have to pay back. There's no need to invoke thermodynamics at all; conservation of energy is right there in the quantum field theory.


Yeah, well, that's just , like, your opinion, man.
 
2011-11-18 02:06:23 AM  

Lord Dimwit: Yeah, well, that's just , like, your opinion, man.


Lemme tell you somethin', pendejo!
 
2011-11-18 09:34:27 AM  

Professor Science: BeesNuts: Interestingly the ability to "create" paired photons DOES make for some cool 'sci-fi' fantasties. If these particles can be entangled and separated, altering the properties of the one will instantaneously alter the properties of the other across any arbitrary distance. We're talking centuries of work towards that specific goal, and several thousand steps between here and there, but quantum mechanics produces some really confusing shiat.

There are a couple of things wrong with this. First, we can already create entangled photon pairs. The current technology for it is kinda clumsy, but it's already good enough for encrypting bank-to-bank communications in some markets.

Second, entanglement does not work that way! You cannot send information via entangled particles; you can only create the same random information in separate locations. The sci-fi instant communication thing is pure -fi, and that's not a matter of technology -- it's a fundamental limitation of the physics involved. I'm not as upset about that misconception, though, since it's much more subtle than the zero point energy thing. The fact that it would violate causality and allow you to send information back in time should be a pretty big tip-off, but recognizing that requires at least a passing familiarity with relativity.


Ok, perhaps instant would be a misnomer. But faster than light? Would that be an unreasonable conclusion? And is the randomness of the information an insurmountable physical obstacle?

Regarding the creation of entangled particles, which I'm only somewhat familiar with, but aware that it's been done:
I was thinking more that since virtual particles are blinking in and out of existence in a vacuum all the time, and since we have just proven that these virtual particles can be brought into observable existence, and since we can entangle them, could we somehow, someday combine these various quantum phenomena and build some sort of information bridge between here and say, Mars? A distance that would take 3-4 hours to traverse at the speed of light. I seem to remember a lot of interest in the potential of artificially entangled particles about 5 years ago, and haven't heard much since.

Heisenberg's a real farker I guess?
 
2011-11-18 12:47:15 PM  
BeesNuts:...Would that be an unreasonable conclusion? And is the randomness of the information an insurmountable physical obstacle?

Yes to the second one, which makes the first one moot for communication purposes. Entangled particles don't really communicate with each other so much as they always tell the same story about their shared history.

Say you have a molecule that decays from an excited state by emitting two photons, and that conservation of angular momentum requires that they both have the same polarization. Nothing about the molecule predetermines which polarization that is, but it has to be the same for both photons. So I know that if I send those photons into instruments that measure polarization, whether instrument A reads out "VERTICAL" or "HORIZONTAL" is going to be random, but instrument B will read out the same as A.

The weird part happens when you look at the quantum mechanical description of those photons, and realize that they don't know which polarization they have until they're observed. Until one of them interacts with something macroscopic, each one is a 50/50 superposition of vertically polarized and horizontally polarized. There's some math and measurement you can do (or rather John Bell and friends can do) to prove that the photons can't make this decision in advance. The spooky thing is that photon A will always make the same decision as photon B, no matter when or where that decision is made, provided you didn't fark around with them in the meantime. This is absolutely necessary for fundamental physics to hold true -- if they could make independent decisions, you'd wind up seeing angular momentum disappear or appear from nowhere.

So if Alice have a steady source of these entangled photon pairs, and she can send one member of each pair down an optical fiber to Bob, they can both generate the same stream of random bits (turn V and H on the instruments into 1 and 0) in two separate places. If you add in a normal, insecure phone line between them, then there are some tricks they can pull to tell whether or not their quantum channel is being eavesdropped upon, but that adds more complexity to the discussion than I want to go into here. This is absolute tits for encryption, and it's already being used in commercial systems. They suffer from limited distance (fiber optics eat photons over a few dozen miles) and low speeds (generating the photon pairs is clumsy, and generating too many at once compromises security), but they do work.

That condition about not farking around with them in the meantime deserves some attention, too. If you go and mess with one of them, like bouncing it off of a surface that scrambles optical polarization, then there's no reason for its polarization to be related to the other one. Doing anything that sets the state of one photon forces it to forget that it used to agree with the other one, so the entanglement is destroyed. And once you make that measurement and the photons make their decisions, the entanglement is destroyed. You get one random-but-correlated coin flip out of each pair, and that's it.

Heisenberg's a real farker I guess?

Now you're getting the hang of it.
 
Displayed 47 of 47 comments



This thread is archived, and closed to new comments.

Continue Farking
Submit a Link »
Advertisement
On Twitter






In Other Media


  1. Links are submitted by members of the Fark community.

  2. When community members submit a link, they also write a custom headline for the story.

  3. Other Farkers comment on the links. This is the number of comments. Click here to read them.

  4. Click here to submit a link.

Report