Do you believe in free will? Are people able to decide their own destinies, whether it’s on what continent they’ll live, who or if they’ll marry, or just where they’ll get lunch today? Or are we just the unwitting pawns of some greater cosmic mechanism at work, ticking away the seconds and steering everyone and everything toward an inevitable, predetermined fate?
Philosophical debates aside, MIT researchers are actually looking to move past this age-old argument in their experiments once and for all, using some of the most distant and brilliant objects in the Universe.
Rather than ponder the ancient musings of Plato and Aristotle, researchers at MIT were trying to determine how to get past a more recent conundrum in physics: Bell’s Theorem. Proposed by Irish physicist John Bell in 1964, the principle attempts to come to terms with the behavior of “entangled” quantum particles separated by great distances but somehow affected simultaneously and instantaneously by the measurement of one or the other — previously referred to by Einstein as “spooky action at a distance.”
The problem with such spookiness in the quantum universe is that it seems to violate some very basic tenets of what we know about the macroscopic universe, such as information traveling faster than light. (A big no-no in physics.)
(Note: actual information is not transferred via quantum entanglement, but rather it’s the transfer of state between particles that can occur at thousands of times the speed of light.)
Read more: Spooky Experiment on ISS Could Pioneer New Quantum Communications Network
Then again, testing against Bell’s Theorem has resulted in its own weirdness (even as quantum research goes.) While some of the intrinsic “loopholes” in Bell’s Theorem have been sealed up, one odd suggestion remains on the table: what if a quantum-induced absence of free will (i.e., hidden variables) is conspiring to affect how researchers calibrate their detectors and collect data, somehow steering them toward a conclusion biased against classical physics?
“It sounds creepy, but people realized that’s a logical possibility that hasn’t been closed yet,” said David Kaiser, Germeshausen Professor of the History of Science and senior lecturer in the Department of Physics at MIT in Cambridge, Mass. “Before we make the leap to say the equations of quantum theory tell us the world is inescapably crazy and bizarre, have we closed every conceivable logical loophole, even if they may not seem plausible in the world we know today?”
So in order to clear the air of any possible predestination by entangled interlopers, Kaiser and MIT postdoc Andrew Friedman, along with Jason Gallicchio of the University of Chicago, propose to look into the distant, early Universe for sufficiently unprejudiced parties: ancient quasars that have never, ever been in contact.
According to a news release from MIT:
…an experiment would go something like this: A laboratory setup would consist of a particle generator, such as a radioactive atom that spits out pairs of entangled particles. One detector measures a property of particle A, while another detector does the same for particle B. A split second after the particles are generated, but just before the detectors are set, scientists would use telescopic observations of distant quasars to determine which properties each detector will measure of a respective particle. In other words, quasar A determines the settings to detect particle A, and quasar B sets the detector for particle B.
By using the light from objects that came into existence just shortly after the Big Bang to calibrate their detectors, the team hopes to remove any possibility of entanglement… and determine what’s really in charge of the Universe.
“I think it’s fair to say this is the final frontier, logically speaking, that stands between this enormously impressive accumulated experimental evidence and the interpretation of that evidence saying the world is governed by quantum mechanics,” said Kaiser.
Then again, perhaps that’s exactly what they’re supposed to do…
The paper was published this week in the journal Physical Review Letters.
Source: MIT Media Relations
Want to read more about the admittedly complex subject of entanglement and hidden variables (which may or may not really have anything to do with where you eat lunch?) Click here.
Doesn’t this kind of assume the two quasars (or pre-quasar material or what have you) weren’t in causal contact before inflation?
I would assume yes, but then the state of matter at that point (no pun intended) may have been pre-entanglement. Not sure how that works.
“it violates some very basic tenets of what we know about the macroscopic universe, such as information traveling faster than light. ”
No. No information is transferred during the process. Entanglement cannot be used to transmit a signal instantaneously or faster than light.
True, yes. Thanks. I’ve now cleared that up in the article.
To Manu/ Jason (and any scientists reading this :):
Never fully understood this distinction with quantum entanglement – For example, we are Team A and travelled a light year away and informed Team B that when they see the entangled particle change direction to clockwise this means Zero and anti-clockwise One, then we have potentially established a faster than light communications method, no? (assuming the spin states change instanteously when either Team A or B effect a change)….
I am guessing this FTL comms is not so because of something along the lines of (quoting wikipedia):
”
this behavior gives rise to effects that can appear paradoxical: any measurement of a property of a particle can be seen as acting on that particle (e.g. by collapsing a number of superimposed states); and in the case of entangled particles, such action must be on the entangled system as a whole. It thus appears that one particle of an entangled pair “knows” what measurement has been performed on the other, and with what outcome, even though there is no known means for such information to be communicated between the particles, which at the time of measurement may be separated by arbitrarily large distances.
”
(So I am guessing it has something to do with the measurement/observation itself,ie ‘collapsing the wave’ of probabilities and subsequently having communications of these results conforming to the speed of light?)
I would love any lay-person analogies you or others here could provide to help me understand this ‘spooky action at a distance’ and why it does/could not enable FTL comms..
Okay, here’s a go…
Suppose you have some atomic process that outputs two photons. If that is all it emits then the two photons will have the same polarization so the total electrical states before and after the decay are balanced. But we do not yet know what one of these polarization states is.
The right-hand photon goes through a horizontal polarizer and into a detector. We now know the polarization of this photon because it got through the polarizer, so we can infer the polarization of the other photon.We know if someone else was looking at the left hand-photon then they would detect it with a horizontal polarizer; they would not detect it with a vertical polarizer; and they would have a 50% chance of detecting it with a 45-degree polarizer.
This is how quantum encryption works. You can test one photon, and send off the other to a remote user. If you both agree to measure the photon with horizontal polarizers, or 45-degree polarizers, then you should get a common key you can use to encrypt data. If an evesdropper intercepts the left-hand photon but does not know which way up to have their polarizer, then they get no information. They can’t run the experiment several times because they only had one photon, and they only got one go at it.
So far, so good. You might say that the photons always had a polarization, and you didn’t know what that polarization was, and no spooky action at a distance was needed. The photons have conveyed no information other than their own polarization to two separate sites at the speed of light. This gives two copies of a random key which is handy for quantum encryption, and that’s it.
However, the slightly spooky action at a distance stuff means that the universe at large has to make sure that the experimenters get matching results if their polarizers are aligned. If both the people are a light-second from the source, then the fact that their two detectors are aligned needs to pass across two-light-second’s separation in less time than it takes one of the observers to flip their polarizer. While the actual quantum equations are nice and simple, it leaves a nasty feeling that the universe can only work if you have lots of FTL elves zipping back and fourth, fixing any paradoxes.
I doubt if there are any FTL elves involved, but physicists have to worry about these things, just in case they can design an experiment to catch them at it. The rest of us can trust the quantum maths, which is magnificently successful at predicting what we can measure, and doesn’t model what we can’t.
Can’t really see how this ties in with free will, though…
Thanks for the example and explanation Richard – I sure could have used the help of those Elves when I studied math in school 🙂
To try to put it simply: you can’t “see the entangled particle change direction”, because the entanglement only holds as long as the particles are not observed. Observation of one of them, once, breaks it down forever. Consequently there is no ‘change’ you can effect and transfer, there’s only ‘observation’ (although this may not have exactly the same meaning in the quantum world). The entangled particles in both spacecraft need to be kept hidden at all times until their one and only use.
What is being violated however is the ‘principle of locality’ (see wikipedia).
The point of the article here (and the ‘free will’ debate) is there seem to be far-fetched but annoying ‘loopholes’ in all experiments that have demonstrated entanglement so far, and it’s pretty hard to devise and experiment that would completely exclude them.
See wikipedia pages: Bell test experiments, Quantum teleportation, and also this:
http://backreaction.blogspot.fr/2014/02/a-drop-makes-waves-just-like-quantum.html
Thank you Manu for the concise explanation – it makes sense now – I vaguely remembered about entanglement breaking upon observation.. It all starts to fit now.. I would love to hear more about this experiment and ones like this – I think most people find the inner workings of the universe’s natural laws fascinating and it is refreshing when science brings us non-physicists new understandings..
To answer the first question in the article: Yes, I do.
Is it an estimation, or, is there any scientific research that can support this:
” … but rather it’s the transfer of state between particles that can occur at thousands of times the speed of light….”
There have been many experiments, see these wikipedia pages: Bell test experiments, Quantum teleportation. Also above comments.
Couple of issues with this post. Firstly Aristotle and Plato had very little to say on the notion of free will and how one makes the leap from the closing of (the final) loophole in Bell’s Theorem to establishing whether or not free will exists is pretty much beyond me and seemingly pretty far fetched at best.
Secondly, quantum entanglement doesn’t necessarily imply that there exists action at a distance that violates classical physics premise of the speed of light, i.e. there isn’t necessarily communication going on. It is the aspect of correlation, which MAY imply communication, that lies at the heart of the conflict between classical physics and quantum mechanics. The issue is one of whether or not we can assume that the universe can be accurately represented via a fully local explained (ie the state of any system is governed only by the objects and forces that act on said system), fundamentally realistic (ie things and their properties exists absent of measurement) and fully deterministic model as is assumed in classical physics. This is what is called into question by the EPR Paradox and in turn is further solidified with Bell’s Theorem, which this specific experiment that the article describes is essentially about.
Lastly, my final problem with the article is that although this experiment that is described will rule out the notion that the observer and architect of the experiment is unknowingly effecting the outcome of the experiment, the last supposed theoretical loophole that has not been closed in Bell’s Theorem, it doesn’t theoretically rule out the idea that the state of the universe when these quasars emitted the “stuff” that is used as the basis for the experiment for measuring system A and system B was not fundamentally entangled and therefore at some level predetermined the outcome of the experiment. In other words it just takes the loophole and moves it from the individual who sets up the experiment to the quasars themselves.
Anyway, my $.02. I cover some of this material in my blog (www.snowconenyc.com) which is why I post this for clarification for those who wan’t a better understanding of what’s actually being tested here. There’s a lot of noise and misinformation around this material on the web, and in the media, and its complicated so I can understand why this is the case, which is why I blog and write about it.
cheers
PW