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Physicists Create Quantum Link Between Photons That Don't Exist At the Same Time
sciencehabit writes "Physicists have long known that quantum mechanics allows for a subtle connection between quantum particles called entanglement, in which measuring one particle can instantly set the otherwise uncertain condition, or 'state,' of another particle—even if it's light years away. Now, experimenters in Israel have shown that they can entangle two photons that don't even exist at the same time. Anton Zeilinger, a physicist at the University of Vienna, says that the experiment demonstrates just how slippery the concepts of quantum mechanics are. 'It's really neat because it shows more or less that quantum events are outside our everyday notions of space and time.'"
OK, it's official. Science and technology is accelerating so fast that I can no longer keep up.
Happy?
'It's really neat because it shows more or less that quantum events are outside our everyday notions of space and time.'"
No, not really. You're simply see the macro effects of partial photons interacting, and unwilling to give up the idea of the discrete photon.
If all you can see (and measure) is a photons promotion and demotion of electrons, you an only see the fast shift of the big circles jumping around in this picture, not the slower smaller drift that is happening.
http://i.imgur.com/AUXb2N9.gif
Give up your photon model, it's based on a faulty understanding.
The problem with quantum mechanics is that we suck at measurement. This really does put a spanner in the general workings of testing scientific theory.
At some point, science just got too weird. We had this nice model of the universe with atoms, some laws of motion and thermodynamics. The universe was basically a giant billiards match. It made sense. It was easy to explain. Then we get into quantum mechanics and everything is crap shoot. Multiple universes. Particles that behave differently when being observed. Spooky action at a distance.
Let's all pretend the last 80+ years of science didn't happen and we live under Newton's ideas of how everything behaved. Who's in?
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
If it is actually possible to utilize the entanglement there are a number of commercial possibilities as well as governmental. Communication that is hard to spy on, faster communication across the globe, instant communication with remote operated vehicles on other planets.
But we don't know until we have freed Schrödingers Cat - or has it actually teleported itself to another plane of existence?
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
Hey guys, Einstein just called me using GravePhone(tm) and he had the following to say:
"Okay, maybe God does play dice, but I still stand by the law of conservation. God doesn't just make shit up. Now if you'll excuse me, Aristotle wants some one on one on the basketball court."
#fuckbeta #iamslashdot #dicemustdie
Let me guess, tl;dr?
This is probably a measurement error that the media will make sure to overhype again. I wonder how many paradoxes you can create if it were true. Cats can prey on the grandparents of the scientists of the future before the scientists are conceived. Yet these scientists may have the control over the cat's life/death before the cat has the chance to kill anyone.
The same forces that are moving the sun through space are also acting on the earth itself. So, no.
File under 'M' for 'Manic ranting'
Can we use this trick to create closed time loops?
B sends message to A using ordinary speed-of-light (or even speed-of-sound) communications.
A sends the message back in time to B, via entangled photons, since B can measure his photon before A's photon ever existed.
Plot twist: B never told A that the original message came from the entangled photon experiment, and A never told B that his message came from B.
How is mesagge fromed?
It looks like quantum teleportation meets delayed choice.
Credo sim. - I think I am.
Possibly using excessively hostile phrasing, but this poster is right-- I'd say the chances of the results not being reproducible are high.
Special Relativity makes quite clear that if two particles are spacelike separated when measured, that the concept of "instantaneous" is devoid of meaning.
If you have this kind of distance than you will have just one special reference frame where this is true, and infinite more where the events are arbitrarily separated in time. This is already at the core of the EPR paradox.
I.e. that you can have entanglement across time follows trivially from SR and the EPR paradox.
It's just astounding how many times the very same insight can get repackaged and sold as new.
Timeline really iiiis real!
Ooooh, So much ooohs.
Somehow, suddenly I want to play Monkey Island again.
`echo $[0x853204FA81]|tr 0-9 ionbsdeaml`@gmail.com
If I had a machine, and it could only see the large circles, then all I would see is the large circles.
If I then made a model of how the large circles appear and disappear, that model would be correct, it would fit the data, it would show the probability of the circles appearing as they jump around. Those circles will jump, they'll go backwards in time, they'll do kinds of weird things.
So my equations all work, and my model of jumping circles works, ergo my model is correct?
Except it isn't, its a function of the limitations of the machine used to observe the underlying effect.
"then the Rayleigh-Jeans formula is completely correct. Never mind that it predicts that all blackbodies should be emitting radiation with infinite power"
So how fast is light really traveling in this crazy new world?
We already knew that.
Whatever "we" you mean count me out.
According to GR gravity is facilitated via a retarded potential, and of course GR survived so far every conceivable test and has been shown to make correct predictions were Newtonian gravity failed.
So no, gravity does not operate faster than light.
Rubbish. Gravity is not FTL, and your argument is BS.
Some time ago I gave some thought to the apparent anomalies and strangeness of the quantum world.
Here's what I came up with as a theory It's all about time
Comments would be welcomed from all the (real and wannabe) quantum physicists out there.
I doubt this is BS, sounds authentic to me. Quantum mechanics is weird. As for the "outside ... space and time", note that the missing words from TFA are "outside everyday notions of space and time". In other words, outside our common sense.
When you read the article, this isn't actually too controversial. All that's being done is changing the timing of of when the measurements are taken and when the intermediate photons become entangled. It's really just using the entanglement process to spread out the time over which the quantum state data is transmitted. You basically have a quantum data historical record.
I can certainly see this opening up useful new capabilities in quantum computing and measurement of quantum phenomena, but it doesn't change our understanding of quantum events and how they interact with our "everyday notions of space and time.".
Superposition, wave function collapse and other quantum effects are supposed to govern everything. But I don't seem to recall any such weird experiments that do not involve any particle traveling slower than the speed of light.
Are there any such demonstrations that involve only interactions between particles having nonzero rest mass?
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
Without quantum physics the cameras, fast CPU, GPUs and high speed communications that help me cope with my solitude at night wouldn't exist. Count me out brah.
Yeah, this. What the AC may be confused about is that faster than light travel is (as far as we know) not possible in space, but the distance between two points can increase faster than light could travel because there's nothing stopping space itself from expanding that fast.
sub f{($f)=@_;print"$f(q{$f});";}f(q{sub f{($f)=@_;print"$f(q{$f});";}f});
I'm pretty sure we already know the answer. The cat is dead. Curiosity killed it.
Check out my sci-fi/humor trilogy at PatriotsBooks.
The distance between two objects does not increase faster than light relative to each other. You need to study the Lorenz transformation equations.
https://en.wikipedia.org/wiki/Lorentz_transformation
If one object far away is moving .9 times the speed of light away from you and another object, in the opposite direction, is moving .9 times the speed of light away from you then those two objects, relative to each other, are not moving faster than the speed of light away from each other. They are moving like .99 (or whatever, you have to do the calculations) times the speed of light relative to each other.
Lorentz transformations only cover special relativity. In general relativity, you can indeed have the distance between two points grow faster than light. Of course not if the points are at the same place.
The Tao of math: The numbers you can count are not the real numbers.
Except that the Earth's motion relative to the galactic core already roughly matches that of the Sun (relative to the galactic core).
Lern2frameofreference.
Precisely.
OK, not precisely. Two points at the same place at the same time is one point, not two points. But I knew what you meant.
sub f{($f)=@_;print"$f(q{$f});";}f(q{sub f{($f)=@_;print"$f(q{$f});";}f});
????
by TheSpoom (715771) Uncaring Linux user here. I have nothing to add to this but please continue. *munches popcorn*
s/much/many/g
Just waking up and writing in non-native language requires coffee.
`echo $[0x853204FA81]|tr 0-9 ionbsdeaml`@gmail.com
Yes! Subspace communications!
Question: Within the context of quantum mechanic, what is the behavior of TIME ?
What I read from TFA is that they observe a certain particle at the before time frame, and then compare it with another particle at the after time frame, and found some "entanglement"
What if the experiment is carried out on the reverse --- someone checking out a particle at the after time frame and then, some others compare it with another particle at the before time frame and see if they entangle or not
I do understand that experiment that I have just described can't not happen with the limited technology that we have, for the after can not happen _before_ the before
That's why I am falling back to my original question --- what is the behavior of TIME within the context of quantum mechanic ?
Can an "after" happen _before_ a "before" ?
Muchas Gracias, Señor Edward Snowden !
According to the article, particles 1 and 4 do not coexist. Therefore, one must be destroyed before the other is created.
But if 1 is destroyed before 4 is created, then the entanglement of 1 and 2 is broken before 3 and 4 are created (because 3 and 4 are created together, and then 2 and 3 are entangled).
So, by the time 2 and 3 are entangled, 1 does not exist, because 3 already exists and is entangled with 4.
The question that arises is then how do they know that 1 and 4 are entangled?
It could simply be that 1 and 4 show the same state when measured, because 1 and 2 were entangled, then 3 and 4, then 2 and 3. Which means that whatever entanglement existed between 1 and 2 will exist between 1 and 3 and 1 and 4, even if 1 does not exist.
That does not mean particles are entangled across time. It may mean that entaglement is simply peristent and transmiitable.
Most probably there is a misunderstanding somewhere between the announcement and the article, so please anyone that knows more, elaborate.
Entanglement exists outside of reference frames. So, it exists across time.
This means that there is a super reference frame which includes all possible frames and allows for things to persist (and perhaps move) across time.
Lorentz transformation and Einstein's theories govern motion in space. Space itself can expand at much greater velocities than c. The Observable Universe is something like ~80 billion LY across (today), but the objects furthest from us are ~14 billion LY away (when they emitted the light). If space could not expand faster than c, it would only be ~14 billion LY across today. Look up inflation if you're genuinely interested.
... whatever
Everything is theoretically impossible, until it is done.
Robert A. Heinlein
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
Now I understand Einstein's wild hairdo....
I think the rabbit hole may be a wormhole without the other end!
*head asplodes!*
Down With Slashdot BETA!!! I've been around the corner and seen the oliphant; you can only abuse me from your perspecti
So what's stopping space itself from contracting that fast, ie reducing the distance between two points?
"Nine times out of ten, starting a fire is not the best way to solve the problem." - my wife
Rubbish. Gravity is not FTL, and your argument is BS.
I suspect a whoosh might be in order here... "The Sun is of course moving" should have been a dead giveaway.
They could only be connected to other particles that existed in their lifetime and then they would have to perform a good deed before being able to connect to a different particle. Oh boy
Number stations and one time pads already fill the need for "spy proof" communication.
Tomorrow is another day...
Dark energy - a term coined to hide the fact that "we don't know". Dark energy seems to be accelerating the expansion after a period of deceleration, this is baffling but fits observational results. The theory is that gravity used to slow the expansion down, but apparently we passed a cut-off point where space has become stretched enough so that gravity is too weak - another force is taking over and stretching space again. A force with no obvious cause, not to us at least.
... whatever
Entanglement can be used to exchange keys for secret communication. It allows two parties to create a shared key without anyone being able to intercept it. In principle, this key can be as long as the message itself and perfectly random, so a simple 'xor' operation is all it takes to make the message completely undecryptable. In more detail:
Alice wants to send a secret message to Bob.
They (or anybody else, really) create a bunch of entangled photons, half going to Alice and the entangled counterparts going to Bob. This all happens at normal speeds (not faster than light), but can be prepared in advance.
If anyone tries to eavesdrop during transmission of the entangled photons, Alice and Bob are able to detect the fact that the photons are no longer in a superimposed state and start over with a new bunch.
Now Alice and Bob measure the photons. They have no control over the outcome of the measurements, which will be completely random, but they do know that they will both get the same result (or rather, exactly the opposite result). This becomes their cryptographic key.
Now Alice encrypts her message with this key and sends it to Bob using traditional communication channels, for example a carrier pidgeon.
Bob uses his identical key to decrypt the message.
The only faster-than-light part of the story is that the entangled photons "chose" their state at the time of the measurement. Before the measurement, they were in a superimposed state. This means the information for the key didn't even exist yet in any way and can therefore never be intercepted by anyone. It only came into existence at the time the photons were measured, simultaneously for Alice and Bob. (Take the word "simultaneously" with a grain of salt, because as the article shows, they can even be separated in time). And the encrypted message without the key is just a series of random bits.
Since this article will (hopefully) attrackt people who are into QM, let me ask 2 questions that I'm struggling with for a long time (and thank you in advance for bothering to answer):
1) What is a "measurement"? How big should an object be to actually "collapse" the wave function?
2) The FTL (well, actually instant) "spooky action in the distance". If particles really can interact like that, how come we can't use it to transmit information? And if we can't, why "hidden variables" assumption that particles had certain values upfront is disregarded?
Because the information needed to test the entanglement requires conventional transmission. There is no way to prove the postulated quantum teleportation of the information. Or both particles need to be created under lab like perfect conditions and moved apart. Which won't happen faster then relativistic speeds. Therefore we observe no breaking of causality.
I think a few people have claimed causality breaking on occasion but the general scientific consensus is that isn't what is happening. There was a much more interesting experiment out of Los Alamos which I do not remember where they tested causality in time in a fairly robust way that leads me to believe it may be possible. But I cannot remember and cite it =/. It was also backed by the Chinese in a later experiment. But they have been getting a lot of raft for bad science and research lately.
I think in the most simple terms the experiment went like this:
Particle A set was measured having a statistically consistent result, particle set B was not measured.
Particle set A was measured again.
Particle set B was measured for the first time and had a different result then particle set A.
They postulated that performing the measurement #2 is what caused A's measurement to be consistent.
The interesting bit of the experiment was how they were measuring particles. However I can't explain it.
In other words IANAPhysiscist and you should take what I am saying here with a grain of lots of error inducing salt.
it is possible that life is a mixture of quantum state and this dimension. Thus the reason for being able to think and have a feeling of self?
Space itself can expand at much greater velocities than c.
To explain this in a little more depth, what we call "space" is really just tied to an arbitrary choice of space-time coordinates. If we choose a different reference frame, distances and times will be different. Just to give a silly example, if I define a meter to be the width of an atom, or if I define a second to be the time required for the earth to go around the sun a thousand times, I can easily travel faster than c. So how does this apply to cosmology and general relativity?
Depending on the coordinate system you choose, the universe can really look radically different, even to the point of no longer being infinite. I will give two possible views, both equally valid even thought the first may appear strange. (So read the rest as well before labeling it as rubbish).
You can apply a classic "special(ly?) relativistic" coordinate system to the universe, with us at the center. The speed of light is the same everywhere, relative to us, just like Einstein said in the beginning. Things that are far away from us are moving away at high speed (but less than the speed of light) and are therefore aging more slowly. This means that some far away galaxy isn't just younger (defined as the amount of local evolution after the big bang) because we had to wait for its light to get to our telescope, it actually is younger "right now" even if we take the traveling time of light into account. Local clocks are really advancing more slowly. The effect increases with increasing distance, and at a distance of c times the age of the universe, the big bang is happening as we speak. Right now. This also means that the universe is finite (assuming nothing existed before the big bang, which is a big assumption). Not that it matters much, because we could never reach this "edge" anyway. It is retreating at the speed of light.
This model is quite interesting but a bit cumbersome for cosmology, so most people prefer to use the "cosmological model". They simply adjust the coordinates of time and space so that the whole universe is the same age and looks roughly the same everywhere, "right now". See, we just changed the definition of "now" and chose a coherently matching set of space coordinates so everything looks rougly the same size, that's all we did. In General Relativity, we are completely free to do so, you can pick pretty much any coordinate system you like. Things can move from the future into the past and back again as we change our variables, without impacting causality (which is all that matters).
Using the cosmological model, the universe is now truly infinite, the big bang is in the distant past everywhere and all the clocks are running at the same speed (as long as they are stationary relative to "space", i.e. moving away from us at the same speed as the average local galaxy). Now, however, the assumptions of special relativity no longer hold. In particular, the speed of light is no longer the same everywhere. Light speed is still the same everywhere locally, relative to "space" (the speed of the average galaxy in that area), but you have to take the properties of our peculiar coordinate system ("expanding space") into account. If at some distance, "space" and the objects in it are expanding away from us faster than the speed of light, the light from those galaxies will never reach us since it will actually be retreating as if it were running towards us on a conveyor belt moving the other way at a higher speed. The conveyor belt isn't "real", it's just an artifact of our choice of coordinates which does not comply with special relativity.
In the first model, those distant galaxies simply never come into existence since the local "space" is asymptotically stuck at a time shortly after the big bang. Things over there are moving away from us at increasing velocity approaching c, and time (rate of aging of that part of the universe) is grinding to a halt.
But do those places exist or not?
He knows.. which is why he corrected himself...
I was just watching a PBS Nova on quantum stuff and one of the more recent tests involved entangling two quantum photons, sending one of those photons several miles away, then entangling the local-photon with another non-quantum photon, causing the local-photon to take on the opposite state of the known-photon, causing the remote-photon to take on yet that photons opposite state, effectively re-creating the exact state of the known-photon, instantly, but destroying the known state of the local known-photon.
This caused that state of a known photon to be transferred faster than light, but did destroy the known state of the original local known-photon in the process. The Doctor said based on this finding, we can transfer information faster than light, but not without destroying the original.
This experiment has been repeated by the same team several times and seems to be very hard to pull off, but is getting setup to be reproduced by others.
That is unless a leading Doctor in quantum physics on the PBS Nova channel is not a reliable source and assuming it's reproducible by other teams.
Interesting detail: If dark energy really exists and is responsible for making the universe expand, then it would be a kind of "anti-gravity"?
Gravity is less than or equal to light. Earth will continue to orbit where the Sun was for 8 minutes. About the exact same time that the light disappears, we will suddenly start moving in a strait line again.
Space near a blackhole can be distorted in a way that causes the space to move faster than c, keeping light from escaping. This can cause light to move backwards relative to an object. Relative to the space that the photon is in, it is still moving forward at c.
Of course I disregarded gravity in my post. Black holes are a whole different ball game. But there too, you can use different coordinate systems to get different interpretations of the events, always yielding the same tangible results.
For example, you could easily argue that, at this moment, no black holes exist. Just before the black hole really becomes a black hole, local time will have slowed down so dramatically that it never actually becomes a black hole. It's forever stuck at the stage right before becoming a black hole. But change to a different reference system and there you go, they exist after all. Just change your definition of "now". In the second system, light inside the black hole may actually be retreating away from us even though it was aimed in our direction while in the first system, it is simply never emitted. I bet people have come up with reference frames that have time going backward inside black holes too. Or going imaginary (the complex number kind of imaginary). But no matter how you define your seconds and meters, you'll always get the same results if you apply General Relativity.
The Earth is approx. 8 light-minutes from the Sun. The Sun is of course moving. If the Earth revolved around where the Sun was 8 minutes ago, it would long ago have drifted out of the solar system.
Wow, you suck at basic Newtonian relativity. How's that even possible?
Ezekiel 23:20
I doubt this is BS, sounds authentic to me. Quantum mechanics is weird.
Well, after I had read that the double slit experiment works for such large things as buckyballs (C60), I vowed not to let myself get surprised by QM anymore. So far, I haven't faltered. :-)
Ezekiel 23:20
Wish I had some mod points right now - thanks for taking the time to explain this!
It's worth noting here that neither point need actually move (or they could be moving towards each other a significant portion of the speed of light). It's the space in between which is growing longer.
but if you are able to detect if photons are superimposed then you are able to transmit information faster than light violating causality. Or do you mean detecting by trying to communicate with differing keys?
Ah, thanks for this. So, it sounds like it's probably possible to preserve a quantum state over time, which is good for us in the real world where things tend to break and get lost.
This must've been what Scotty did when he put the pattern buffer into its diagnostic cycle. Except, poor Franklin, in the real world things break and get lost.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
We're very good at measurement. Quantum mechanics only says that you can't measure everything exactly at the same time, you have to make lots of measurements and use statistics. Which is what we do anyway.
You can only detect the superimposition given information transmitted in a normal way, so you can never detect it faster than a normal signal takes to travel to you.
That's a pretty silly example, seeing as how it's wrong. If you choose to define a "metre" as the "width of an atom" then you will still not be able to win a race with a beam of light any more than I could run faster than a Ferrari. You might be able to travel more metres per second, but so would the light.
Do you not believe that the Sun is moving?
Multiverses can interact !
Maybe we deserve this world ?
http://gizmodo.com/government-lab-admits-to-using-quantum-internet-for-two-493293340
Is less more more than more less ?
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Sorry, I don't have the time to RTFA, but it seems strange to talk about entangled photons that don't exist at the "same time" when SR say simultaneity is relative. While they might not exist at the same time in one reference frame, you'd think there's bound to be one in which they do.
Happy people make bad consumers.
Edgy... You keep using that word. I dont think it means what you think it means.
Whenever a player quits EVE to go play WoW, the Average IQ of both games increase.
Time is relative too. If you and I are in the same room we appear to be in the same "time" the same way that the Earth appears to be flat, because the difference is too small to notice. But the "time" of you or I or any given particle is as distinct as its space. Of course, the ramifications are not quite that simple (because of time's arrow, etc), but it seems well within accepted theories.
At least, that is my take. I am a physics hobbyist, so it is entirely possible that I have completely misinterpreted the underlying theory. If I did, uh, well, sorry, and best of luck with all that photon stuff!
Dark energy - a term coined to hide the fact that "we don't know".
It's not a term to hide the fact that "we don't know", it's a term to punctuate that "we don't know". If we were really trying to hide stuff, we'd define it as stuff we already know about rather that come up with a new term (like the MOND guys are doing with dark matter).
Yes, have to agree. Couldn't a valid observation of this experiment be that "the entangled property of photon 2 does not change with time"? This would explain things without having to violate "everyday notions of space and time". At least, no more so than usual.
This spooky action at a distance thing is hogwash. All the data points to random persistent polarization. Once a pair of entangled photons are produced they each have a definite polarization that persists over time and space unless you do something to it. That is Newtonian. A body in motion remains in motion until acted upon by an external force. A photon polarized at an orientation remains in that orientation until acted upon by an external force that changes the orientation. Creating a new photon polarized the same as an existing photon is not spooky.Hard to do and maybe very useful but not spooky. The Bell experiment / theory has been badly abused and interpreted in an odd way. Its results show conclusively that once photons are created in an entangled way the polarization of the individual photons remains aligned between those two photons. It proves that the unassigned BS is BS. The polarization is a definite fixed value and stays that way until you do something to the photon to change it. Saying its polarization is all orientations until the wave function collapses is not accurate. One photon has one polarization. We do not know what it is until we measure it. Because we do not know what it is does not mean its polarization is undefined. Undefined Unknown. The population of photons have a random range of polarization. But each entangled pair have a matched polarization.
Actually, they would have to compare some subset of the key over a classical channel, to detect eavesdropping and then use the remainder of the key for the actual secret communication.
Yes, light speed would be orders of magnitude greater than c with those silly definitions. Which is exactly the point: both light speed and the speed of local objects at different places in the universe can be different depending on which reference system you use, and this explains why things can go "faster than light" in some models, and light speed isn't always 'c'.
To make the comparison a bit more accurate: suppose I defined a non-cartesian reference system where the size of a metre depends on the distance to earth. Here on earth, it is the width of an atom but on Mars it's the length of our traditional metre. I can then go "faster" on earth than a ray of light on Mars since the ray on Mars is only doing 300000000 metres per second and I am doing more "metres" per second here. Of course that's still a silly example, but it's quite similar to what's happening in the cosmological model.
A reference frame that obeys special relativity will have the same light speed everywhere, and all objects will travel slower than c, but in the cosmological model light speed will have "the expansion of space" superimposed on it and objects travel away from us at speeds higher than c (but slower than local rays of light in the same direction). It's all just because of the coordinates used. Normally, objects moving away from us at high speed will be contracted in the direction of motion but the cosmological model uses contracted metres that make everything the same size again. And the scale keeps changing as the universe expands, artificially "moving" objects to ever greater distances. And clocks are artificially sped up. All of this throws Special Relativity out the window.
No matter which reference frame you use, you will never be able to outrace a beam of light at the same location as you. But you may be able to go "faster" than a beam of light that is many billions of light years away, since the "faster" just depends on arbitrary measurements without a direct objective relationship. In any case you can't actually physically pass a beam of light in the same direction as you.
"Things are only impossible until they're not." -Captain Jean Luc Picard
No two objects in space move away from each other, relative to each other, faster than C.
Just to make a tiny correction: relative to each other, as measured by one of them. If we measure them, using our reference frame, we will definitely see them moving away from each other at a relative speed of 1.2 c. Each second, the distance between them will have increased by 1.2 light seconds. But if you are on board of one of the objects, you will have a different clock and different distance scales. You will then measure 0.88 c.
Everyone thinks that because one galaxy is moving away from me, relative to me, at .9 C in one direction and another is moving away from me at .9 C in the opposite direction (relative to me) then they are moving away from each other at faster than C. Not relative to each other though.
Well, if they are moving away from us at that speed due to the expansion of the universe, and everybody uses the cosmological model, then even the aliens in one of the galaxies will agree that the other galaxy is moving away from them at 1.8 c. Because that's due to "the expansion of space" (or in other words, the peculiarities of the cosmological model). If everybody uses models based on special relativity, the aliens will only measure the other galaxy at 0.99 c.
You seem to be confusing c, the speed of light in a vacuum, with 3.00 x 10^8, the number describing the speed of light in a vacuum using units defined to particular international standards. The speed of light doesn't change when you measure it in m/s, km/h or ft/day. You can of course define any units you want, with any silly inconsistencies you want, and can make up all kinds of silly results based on those. Real measurements aren't arbitrary, although they can be made to seem so when you choose an inconsistent measurement system. We try not to do that.
The definitions of coordinates used in cosmology are far from arbitrary and have objectivity. There is specific meanings behind what distance and speeds mean, although a lot of that gets dropped from actual papers when summed up in more accessible material.
Well, with "arbitrary" I didn't mean to say there were no good reasons for using the cosmological model, quite the contrary. Obviously it's easier to use a reference frame in which the infinite universe is homogenous and the same age everywhere. I'm just saying that it's one of several possible choices of coordinate systems, and other choices would yield different times, distances and speeds. The whole idea of "space expanding faster than light" is in a way caused entirely by this particular choice of coordinates. The special-relativistic model (which pretty much nobody uses, for good reasons) does obey the speed limit but has the disadvantage of not being homogenous and treating our milky way as a special location at the center of a finite universe (like I described in my earlier, great-grandparent post).
I do prefer the cosmological model, but I think it's useful to point out exactly what it means, and where the contradiction with Special Relativity is coming from. Too many popular publications just say "space itself is expanding faster than light, and that explains it" while "space itself" doesn't really mean anything. They make it seem like space is some kind of expanding aether, which of course it isn't. Stuff in space happens to be flying apart, and we just chose a system of coordinates to make the description of the stuff easier. This happens to have the side-effect of creating the notion of an expanding "space" on top of which c has to be superimposed, but that's just a mathematical artefact caused by the choice of space-time coordinates.
You are right that you won't pass a beam of light in the same direction, because in GR it will always locally look like special relativity. But it is possible to have a beam of light shined directly at you, and have it never be able to reach you in finite time, while at the same time have its distance always increasing from the source.
Exactly, and I gave that example in my earlier great-grandparent post. In the cosmological model, the light from distant galaxies will never reach us because space is expanding too rapidly. In the special-relativistic model, that galaxy will never exist in our reference frame since its ancestral matter is moving away from us at a speed so close to c (and increasing towards it) that the passage of time is asymptotically grinding to a halt. Both views are consistent with the actual fact that we will never see that galaxy.
Well, I'm not going to argue about the exact definition of c, but I certainly meant the fixed mathematical value. The silly example just tried to show how it is possible for things to go faster than c without causing any problems with relativity. If you choose a coordinate system that is not consistent with the definitions used in Special Relativity, then yes, you will find speeds greater than 3 x 10^8 m/s. This can be very useful, as is the case with the cosmological model (which, unlike my silly example, does preserve "local" speed of light but not global speed of light throughout the universe).
My silly example served no purpose other than to make the point that speeds are just something measured in some coordinate system and therefore the choice of coordinates can change the values. The notion of a galaxy moving away from us at some specific speed only has meaning if we also describe the reference system being used.
If we are using the cosmological model, it is perfectly normal for galaxies to be flying away from us at many times c. With a different set of coordinates, obeying the definitions of Special Relativity, we will only find speeds lower than c but the universe will look distorted because of lorentz contraction and time dilation. Which is why pretty much anyone uses the cosmological model and explains the resulting high speeds as "space itself expanding".
Do you not believe that the Sun is moving?
Not relative to the Earth's frame of reference it isn't, which is all that matters for this calculation.
that we can send information back in time, like tomorrow's lottery numbers? The outcome of a race? That we were involved in an accident tommorow, and now we can avoid it? Once that is possible, doesn't life as we know it collapse?
Bugger, I'll come in again...
You're right. The four states of matter should be more correctly called the four familiar states of matter, because everything that you can see in your everyday life is in one of those states.
However, the concept of a "state of matter" doesn't actually exist in nature. They're just words we apply to configurations that matter can find itself in, to help organise our thinking.
sub f{($f)=@_;print"$f(q{$f});";}f(q{sub f{($f)=@_;print"$f(q{$f});";}f});
I think the best description of why is "General relativity - causality - Faster than light information transmition: Pick two". Or, more user friendly, in general relativity, FTL communiation is equivalent to the reversal of causility, with event B affecting event A, even though B takes place after A.
Now, we have pretty good evidence for general relativity, and causality also tends to hold up, so the general assumption is that FTL communication cannot happen.
Yeah, this. What the AC may be confused about is that faster than light travel is (as far as we know) not possible in space, but the distance between two points can increase faster than light could travel because there's nothing stopping space itself from expanding that fast.
That's relativity, but the nice thing about this is that you can't actually observe it happening. If you put two golf balls in a room and then expanded the space between them so that they move a light year apart in a second, you'd never see either golf ball moving faster than the speed of light away from you, whether you are viewing from the perspective of either ball, or an observer in the room. You'd just see them move apart at a speed very close to the speed of light.
Objects further away than the cosmic horizon are in theory moving away from us faster than the speed of light. However, if we look at them all we see is a background of objects close to the horizon that are so red-shifted that they're barely detectable at all moving away at almost the speed of light. We can't see beyond the horizon (hence the name), and we can only see the horizon itself as a wash of particles coming from every direction (otherwise known as the cosmic microwave background).
Since the Earth is moving in Sun's frame of reference, Sun is definitely moving in the Earth's frame of reference.
Sun is not moving in its own frame of reference, but nothing really is (if you forget the moment).
Bingo Dictionary - Pragmatist, n. A myopic idealist.
I did disregard gravity since the density of the universe is pretty low on a large scale, so maybe there are some corrections to be made to take the (small) curvature of the universe due to gravity into account, but I think most of my explanation is still valid. If you can just imagine a universe without (much) gravity, I don't think there's anything wrong with the models I described. I will just give them again with a bit more detail:
The first reference system I proposed is an extremely simple one (but with complicated consequences) constructed along the lines of special relativity:
1. Pick some "stationary" point in our vicinity as the origin (of course not the earth or the sun, since they are revolving around the center of our galaxy, but some point in our local cluster of galaxies should do fine).
2. Using a set of standard "measuring rods" (just like Einstein used in his popular description of relativity), which are placed stationary to the origin of the reference frame, construct three perpendicular axes to assign space coordinates.
3. Place a clock at the origin which sends out a signal every second. Clocks are also placed at various other places in the universe and synchronised by listening to the origin clock and applying a correction of distance divided by light speed. A clock located one light second away, for example, would add one second to the received time to indicate current time in our reference frame. All these clocks are stationary in our reference frame, they are not moving with the expansion of the universe.
In this reference system, distant galaxies are flying away from us at high speed and are therefore subject to lorentz contraction and time dilation. They will appear shrunk in the direction of motion, and will age more slowly. They are also closer together because the space between them is lorentz-contracted as well. Obviously, an alien civilisation in those galaxies would consider themselves to be the center, and would say we are aging more slowly than them, but that's just the classic twin paradox and no contradiction. We are free to use our own reference system.
Anyway, using this reference frame, objects at large distances are younger because they have been aging more slowly ever since the big bang. At some distance away from us, objects are traveling at speeds close to c and they are so young that the big bang has only just happened for them. A little bit further, at c times the age of the universe, there's a singularity where the big bang is happening now.
Of course I realise that this is a strange way of looking at the universe, but it obeys the principles of special relativity (disregarding gravity) and therefore has the property that nothing exceeds the speed of light relative to the origin.
The cosmological model, which is a lot more practical to use, is constructed in a different way. Clocks at any point in the universe are set so they indicate the amount of time passed since the big bang as experienced by a local observer that is moving with the expansion of the universe, and distances are measured so that local light speed, relative to a local observer moving with the expansion (i.e. relative to "expanding space"), is c. Now the universe is the same age everywhere, looks the same everywhere (no more lorentz contraction from the expansion), but we gave up the property of nothing being able to go faster than light globally. Local light speed is c relative to local observers who are moving away from us, or in other words, relative to "expanding space". But those observers can fly away from us at speeds well in excess of c.
Am I making slightly more sense now?
The word is made of quips and quibbles, cubistic holo-bits and hobbits of brick-a-brac espoused to melanges of malarkey. A fright-night of fundamental foolery gathers in search of data to complete a theory which states that it, the theory itself, does not exist. Therefore there is no theory, which leaves itself unproven thus possible.
These two photons walked into a bar. "We're entangled!" they slurred repeatedly, making the patrons around them more annoyed than shocked. The bartender turned to face them and the bar dissolved into a branching fog of multi-way almost-events because their entanglement could not exist to be observed and a bartender's eyeball is the lighthouse of the soul. Ask anyone.
Time to pull the chain and flush your mind.
<blink>down the rabbit hole</blink>
I'm pretty sure it is. You can verify this for yourself by going outside twice a day. It's particularly evident if one of those times is, for example, around noon and the other is around midnight. You can also verify other types of movement by watching for the maximum height the sun achieves each day, and by checking it's position relative to the background stars.
More seriously, recognizing the Sun's movement relative to... the galaxy presumably, and the factors controlling that movement, is important to debunking the OP. Illustrative of this, someone made a very pretty, but physically inaccurate, rendering of the sun flying through the galaxy with the Earth trailing along behind it and uploaded it to YouTube in support of his "vortex gravity" theory: http://www.slate.com/blogs/bad_astronomy/2013/03/04/vortex_motion_viral_video_showing_sun_s_motion_through_galaxy_is_wrong.html.
The thing about interpretations of quantum mechanics, is in the end, they don't make any predictive difference. They might make things fit together better in your head, or act as a muse when looking at the math, but in some sense they don't change the experiment. It is just a layer of abstraction on top of the math that works.
Thank you for that as I did see it as their interpretation of the experiment giving them the results they were looking for.
While I see the large lines just fine and lots of quantum physics principles I'm unaware of; entanglement being passed on to
another unrelated event seems a retraction is but a verifying experiment away.