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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.'"
'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
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
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'
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.
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.
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.".
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});
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.
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.
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.
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
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.
keep sending 0's to the end of time... HA! I have you now moose and squirrel!
Do not look at laser with remaining good eye.
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?
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.
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.
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).