In addition to the nice biography about a superb scientist, I also found this interesting:
> Wu might have been hesitant to discuss evidence of entanglement because throughout the 1950s and 1960s, such quantum-foundations work was stigmatized as junk science. Back then, explains David Kaiser, a professor of physics and history of science at the Massachusetts Institute of Technology, the idea of using an experiment to prove or disprove theories about quantum physics or to test for local hidden variables was “not even an inkling” for most physicists. Researchers who explored questions about entanglement often disguised their research because backlash could stymie a promising career.
I suspect their are similar things going on today, like astronomers who want to look for signs of intelligent life but packaging it as something more mundane
The ideas of lines of research being suppressed is a rich topic in science fiction novels. Usually hidden aliens or secret factions on Earth actively steer scientists away from certain topics, usually that will lead to break throughs in star drives or weapon-of-mass-destruction designs.
> Usually hidden aliens or secret factions on Earth actively steer scientists away from certain topics, usually that will lead to break throughs in star drives or weapon-of-mass-destruction designs.
What about if SETI@home had been programmed by aliens, so we all thought we were looking for them, but the code would never find them? :)
Ther eality of research suppression is much more mundane, and illustrated well in "The Trouble with Physics" by Smolin. Basically with the way the tenure and granting systems work the only way to get a degree and a job is to work on whatever the leading scientists decide is correct, which is most often their own ideas. At that point anyone who wants to try another approach will be unable to get funding, because all the "leading" scientists don't think it is worth pursuing, and you won't be able to get letters of recommendation and endorsement as a Post-Doc because you aren't doing things that make your tenured boss look good.
I actively reject conspiracy theories on the premise that they’re conspiracy theories. However, I can’t deny that this one is interesting. What if this is actually happening?
Obviously the easiest way to provoke thought within the skeptic is to ask, “If it is within the realm of possibilities for the human race to invent a driver allowing interstellar travel, why shouldn’t an extraterrestrial race also be capable of it?”
I would assume someone would counter with the fact that extraterrestrial life hasn’t been discovered. A question to often revisited. For all we know extraterrestrial life surrounds their inhabited planets with strict ingress and egress policies.
I don't think what the OP is suggesting is necessarily a conspiracy. Institutions are wary of people who risk their credibility with claims that catch a lot of attention but may prove to be false. There's some incentive to make claims that capture a lot of attention and the field doesn't want to lose credibility.
If you think about how some scientists responded to speculation about Oumuamua you can see how they were nervous about speculation that could be sensationalized.
Similar things are for sure still going on. Sean Carroll regularly laments the fact that research of the foundation of quantum mechanics is often actively discouraged.
Yes, i stumbled upon a reddit thread recently where the conversation devolved into actual hate for people who were curious about studying the "why's" of quantum. The most liked comment and prevailing attitude was, "it doesn't affect my research, so i don't care", which makes sense but those same people were getting upset that _anyone_ might want to make it _their_ research.
I'd heard of the hate before but it was so baffling to witness. I left a comment asking for explanations to my above observation and received no replies. As someone who's personally very interested in this type of research, it kinda terrifies me.
You shouldn't pay too much attention to the hate, what you find interesting is intensely personal and few others will ever understand. Foundations is in a much better spot than it was 50 years ago, and you can definitely succeed in it.
Having said that, as someone outside the field who peeks in every once and a while, it does seem like a lot of foundations research (that gets noticed at least) is about constructing flashy abstracts out of simple linear algebra. The interesting stuff always seems to belong to another field, like computation, error correction, encryption, etc. Combine this with many physicists' distaste for philosophy, and you'll get the current attitude towards foundations.
Weird, it seems like that's one of the most popular discussions in pop-sci. The real question is more philosophical... does Many Worlds even mean anything scientific (eg is it testable or a usefully simple model). Certainly, it's entertaining.
He published a paper with some colleagues on a way to disprove Everettian Mechanics. It falls into the difficult but not impossible category. It involves looking for minuscule energy spikes that would be evidence of some kind of "collapse of the wave function" that would rule out Many Worlds.
The Copenhagen Interpretation isn't a theory, it it is an attitude.
The answer to both is "no." It is really obvious that the answer is no, because they lead to the same predictions. There is real work being done in quantum foundations (which is not the same thing as fundamental physics), but it doesn't involve arguing about MWI and Copenhagen. :-)
I’m not sure about what precisely you’re referring to. There is an entire school of mathematics that dismisses the law of excluded of middle and I’m not sure why that would not be “real work”.
Didn't you say you can't tell whether randomness is true or due to incomplete interpretation? If Copenhagen is incomplete, then it doesn't work, only its one part works - the Schrodinger equation.
It doesn't predict collapse if that's what you mean, because collapse doesn't happen, but it predicts that the result of observation is eigenvalue, and the prediction is consistent and matches observation.
MWI is confirmed in a sense that it exactly matches the Schrodinger equation and doesn't add anything contradictory or ad hoc hypotheses, and is compatible with the rest of science. And the Schrodinger equation is verified quantitatively. This is as far as verification goes.
Aside: both Kaiser and Carroll are above-average speakers and worth your time to see if you have the opportunity. They are professionals giving professional-physicist talks, though.
It is worth pointing out that zero actual information is transferred, it's just an inexact analogy to describe a problem space which lacks terms in plain English to describe it. It's not possible to communicate faster than light with this mechanism. What can be done is to generate same random numbers in two and only two distant places at the same time. That has great application in secure communications because it bypasses the entire need for potentially insecure key exchange mechanisms, but because the numbers generated are truly random they contain no information and this mechanism cannot be used to cause an effect faster than light, it does not violate relativity in any way.
Quantum wave functions represent a probability distribution for the characteristics of an object in quantum mechanics, such as a particle or photon. When you measure it, that probability distribution resolves to a discrete value. So basically when you measure the spin of a particle, god rolls some dice to determine what it is. That’s one interpretation anyway.
So couldn’t you send a bunch of entangled particles somewhere and collapse the wave function on them in sequence in some way as to communicate faster than the speed of light?
All you can do with your half of the pair is observe its state after the wave function collapsed. Whether it collapsed because you just poked it or because the other half of the pair was poked first can't be known without comparing notes afterward using classical means.
An interferometer can differentiate that. If a photon is in superposition, it exits interferometer on a certain path, if it's collapsed, it exits on a random path. If you send 100 such photons, you can send 1 bit this way with good precision.
Although not informed enough to comment on this, I do know that if it was true, it would break relativity and that would have come across my feed at some point.
I made it up. Any nonlocality breaks relativity, this doesn't break it further. You can still say the same thing - it's okay because why not. Or you mean it will be a paradox if they receive a message in the past? I guess it can be prevented if the entangled photon doesn't interfere with itself.
Information cannot move faster than the speed of light. If the non-locality has a random output, then it doesn't violate relativity because random noise cannot carry information (by definition it's no longer random if it does).
That's the trick - to replace random process with deterministic process which is still sensitive to collapse. Or rather make collapse switch from deterministic to random process.
Whether or not the photon is collapsed isn't the process that makes entangled particles "spooky" though. (Sorry I should have originally stated this)
Its that they have opposite states when you collapse them. So collapsing one doesn't collapse the other. Its just that when you collapse one (by measuring it) you can know the state of the other (even if it's on the other side of the universe).
The real "spookiness" is that the particles don't have a predetermined state "underneath" their superposition. When you collapse one its odds of being heads or tails are 50/50 up to the moment you collapse it. And when you collapse it you know what reading you will get when you collapse the other one.
Did you try to describe Everett's interpretation? There observation of one particle doesn't change the state of the other indeed. If everything is local, then no FTL is ever implied. In copenhagen collapse is nonlocal and happens instantaneously across the universe, so FTL actually happens.
>In copenhagen collapse is nonlocal and happens instantaneously across the universe, so FTL actually happens.
I don't know if this is a mathematical deduction or something empirically verified. Technically when you measure one particle the wave function of both collapses, because now you know what the properties of the other particle are.
But it could be like a pair of dice that always land on opposite faces. When the first die lands, the fate of the second die is sealed and it's no longer in a "superpostion" despite the second die still tumbling around in the air. I strongly suspect this is the case, because otherwise, like you said, you could transmit information faster than light, breaking relativity.
That's more or less right, as far as I know. Manually turning one of the dice doesn't manipulate the other one, and tossing your die only tells you what the other die did or will come up if it's ever thrown. It doesn't tell you if it was thrown.
Any superluminal signalling method proposed using entanglement has to explain which assumption of the no-communication theorem it's negating, otherwise it's breaking the known laws of quantum physics. Also, explain why nobody's noticed this effect in the lab before and sold it to high frequency traders and then won the Nobel prize.
wikipedia says: there can be also cases where is still possible to communicate through the quantum channel encoding more than the classical information
What I propose is to switch between deterministic and indeterministic process, the former encoding 0, the latter encoding 1. Maybe indeterministic process counts as more than the classical information. Also since it's indeterministic, it has a small chance of miscommunication. Since communication isn't precisely certain, maybe the theorem treats it as failure.
Wikipedia is referring to superdense coding, which is not superluminal and still needs you to physically send a particle from place to place to transfer the information.
"an entangled state (e.g. a Bell state) is prepared using a Bell circuit or gate by Charlie, a third person. Charlie then sends one of these qubits (in the Bell state) to Alice and the other to Bob. Once Alice obtains her qubit in the entangled state, she applies a certain quantum gate to her qubit depending on which two-bit message (00, 01, 10 or 11) she wants to send to Bob. Her entangled qubit is then sent to Bob who, after applying the appropriate quantum gate and making a measurement, can retrieve the classical two-bit message." (emphasis mine)
Alice physically transmits her qubit to Bob, so it's not superluminal and doesn't break the no-communication theorem.
Okay, I found my error: deterministic measurement I proposed is impossible, it works only for factorized state, but entangled state produces second spooky result with uniform distribution, so collapsed photon is indistinguishable from noncollapsed.
Mathematically speaking entanglement is local: in entangled state |11>|22>+|12>|21> the state |11> coexists with |22> and not with |21>, so when the particles fly away and meet again, |11> still meets with |22>, it's sealed at the time of creation of the state.
Think of the two entangled particles as telegraph operators that can communicate with each other infinitely fast -- the speed of light is no obstacle for them. But you cannot hand one of them a message to be transmitted because they simply ignore you.* You can ask either of them if they recently sent or received a message from the other, and what that message was, and they will tell you the truth. But they will only tell you this over subluminal channels, and they will not accept a message to be transmitted superluminally. We can prove they are communicating superluminally because of the Bell inequality, but we cannot control what they are communicating.
*More precisely, the act of handing one of them a message causes that one to communicate some random message to the other.
> Wu might have been hesitant to discuss evidence of entanglement because throughout the 1950s and 1960s, such quantum-foundations work was stigmatized as junk science. Back then, explains David Kaiser, a professor of physics and history of science at the Massachusetts Institute of Technology, the idea of using an experiment to prove or disprove theories about quantum physics or to test for local hidden variables was “not even an inkling” for most physicists. Researchers who explored questions about entanglement often disguised their research because backlash could stymie a promising career.
I suspect their are similar things going on today, like astronomers who want to look for signs of intelligent life but packaging it as something more mundane