For A Good Time In Cambridge This Evening (Tonight!)

Boston-area jackals:  there’s a cool event going on at MIT tonight.*  Sorry for the short notice, but they didn’t tell me until this a.m.

Anyway: PBS’s NOVA series will be broadcasting a new episode at 9 p.m. tonight.  It’s called “Einstein’s Quantum Riddle” and it will be screened in its entirety (not much pre- in this sneak preview) at MIT beginning at 7, with a discussion to follow.  Details are in the poster below.

The program focuses on an international collaboration to test whether or not quantum entanglement (violations of what is known as Bell’s inequality — an concept that states that quantum mechanics makes predictions that are incompatible with those based on a classical understanding of how events occur.

That understanding, BTW, often called local realism makes two claims: that cause and effect connections cannot occur faster than the speed of light, and that any particle being observed has a real “true” value that exists before any experiment is performed.

It gets significantly more subtle and complicated from there, and well above my pay grade to explain, (though not beyond that of several commenters here).  Most simply: ordinary experience and (more or less) all of physics before 1925 tells us that the world follows what seem like common sense rules:  things can’t happen more quickly than the top speed available to us, and it is possible to make always-consistent objective measurements of what’s going on around us.  Bell’s theorem —  again, this is a cartoon version — says that in quantum mechanics, (a theory that we know works for all kinds of reason, not least the behavior of a lot of the guts of the computer on which I type this), this kind of seemingly obvious experience doesn’t hold true.  Particles can be “entangled”:  connected in a way so that a measurement of one particle in a pair determines what will be observed of the other particle, even if they’re too far apart for one particle to “know” what the other particle has revealed, even if a signal passed between them at the speed of light.

This was exactly what Einstein and two colleagues, Boris Podolsky and Nathan Rosen, had pointed out in a famous paper in 1935, claiming that this clash between the classical view and the quantum one meant that quantum mechanics had to be incomplete, because “no reasonable definition of reality could be expected to permit this.”

Unfortunately for Einstein and his EPR colleagues, reality is under no obligation to be reasonable.

Beginning in the seventies, experiments — actual measurements, first on a table-top scale — showed that the quantum view was correct: entanglement does occur.  It violates the local constraint of the speed of light and the requirement that every chunk of a system must have a consistent pre-existing measurement value independent of the choice of what and when to measure it.

Those early experiments were highly suggestive, but not absolutely conclusive, and so, in 2016, an international team of researchers including, on the MIT side, Alan Guth and David Kaiser, devised a way to test entanglement on a galactic scale, using light from a distant star to set a crucial parameter of the experiment.  Using a signal from a far-away source shrunk one of the key remaining loopholes in Bell’s idea.  Since then the team has used light from increasingly distant objects to perform the same role.  Because distance in space is also distance in time — the hundreds, thousands, millions or billions of years it takes any given photon to travel all that way — these new measurements push any possible violation of quantum mechanics ever closer to the origins of our universe.

Anyway, all this will be described, much more clearly (or at least with visual aids) in the film, and then expanded on by the really sharp panel that will follow.

A personal aside: this is a kind of science I truly love:  it is at once fundamental — an exploration of how reality actually works on a deep level — and, at least mostly, purely beautiful.  Bell’s theorem and quantum entanglement do have practical implications, especially for computing and cryptography.  But to a great extent, this is a case of human ingenuity performing at a very high level, producing knowledge that is an abstract form of the same kind of cultural achievement that endows us with Gothic cathedrals or a telescope in space that can reveal to us stars in the process of being born.

I’ll climb down from the pulpit now.

So, y’all — if you’ve got a couple of hours this evening — there’s a seat in a lecture theater in the heart of MIT’s campus that has your name on it.

As promised, the details…(to find the room, building 6, number 120, look for it on this interactive map):

*I can’t go, alas: a family obligation of long standing intervenes. I’d be there in spirit, except I keep the spirits in a cupboard in the kitchen.

Images:  NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI), Wide View of ‘Mystic Mountain’ (a star forming region within the CarinaNebula) 2010

William Blake, Isaac Newton, 1795.

 

 

50 replies
  1. 1
    oatler. says:

    Blake painting kinda reminds me of an Atomic Rooster album I had.

    ReplyReply
  2. 2
    MattF says:

    Quantum entanglement does not violate causality. Period.

    That said, multi-particle (Alice/Bob) events, in which the states of entangled particles are correlated in a non-classical fashion may occur– but you have to ask who, exactly, is computing the correlation, Alice, Bob… or maybe Zebediah– and if you do that, the paradoxes go away. Quantum mechanical descriptions of states are simply not local, and that’s all there is to it.

    My own opinion is that while the pedagogically common one-particle ‘paradoxes’ of QM are widely known and explained, the non-classical behavior that occurs when you cross the line from one-particle to multi-particle systems is not-at-all well explained.

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  3. 3
    🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷 says:

    Some of the paintings you feature are really weird, Tom.

    this is a kind of science I truly love: it is at once fundamental — an exploration of how reality actually works on a deep level — and, at least mostly, purely beautiful. Bell’s theorem and quantum entanglement do have practical implications, especially for computing and cryptography. But to a great extent, this is a case of human ingenuity performing at a very high level, producing knowledge that is an abstract form of the same kind of cultural achievement that endows us with Gothic cathedrals or a telescope in space that can reveal to us stars in the process of being born.

    I have to agree. Though I don’t always understand the science, I’ve always loved reading about physics, especially the kind you talk about here that deals with the nature of reality. I especially enjoy reading about anything to do with space.

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  4. 4
    Amir Khalid says:

    What are George HW Bush’s initials doing at the bottom of the poster?

    ReplyReply
  5. 5
    MattF says:

    @Amir Khalid: The public television station in Boston is WGBH.

    ReplyReply
  6. 6
    Tom Levenson says:

    @MattF: Agreed. I should have said “classical views of causality” — but you are especially right when you say multi particle systems drive one into the tall grass in a hurry.

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  7. 7
    dmsilev says:

    @Amir Khalid: WGBH is a Boston-area television station, part of the PBS (Public Broadcasting System) network. They’re the folks who produce the Nova series.

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  8. 8
    Fair Economist says:

    Another important aspect of the paradox is that the states are not “hidden” in the particles somehow. In the photon case, for example, there would be no paradox at all if one particle were produced horizontally polarized and the other vertically polarized. But other experiments can show neither particle is either horizontally or vertically polarized until it is measured.

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  9. 9
    Amir Khalid says:

    William Blake was in some ways a deeply weird guy. A normal guy would not have conceived of Isaac Newton as a bodybuilder doing his maths in the nude.

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  10. 10
    Tom Levenson says:

    @Amir Khalid: @dmsilev: @MattF: Yes. WGBH are the call letters for the station. W denotes that the station is east of the Mississippi River (radio and tv stations west of it (I think there may be a couple of exceptions, but I’m not sure) get K for their first letter.

    The rest of the call sign is a reference to the location of the station’s first transmitter, the Great Blue Hill in Milton, just south of Boston. There is a station in-joke ruder expansion of the acronym, but I leave that one as an exercise for the reader. (Not the obvious Brit reference to GBH.)

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  11. 11
    Tom Levenson says:

    @Fair Economist: Exactly — that’s the “realism” half of the local realism claim.

    ReplyReply
  12. 12
    Kdaug says:

    “The universe is not only stranger than we imagine, it is stranger than we can imagine”

    ReplyReply
  13. 13
    Amir Khalid says:

    @MattF:
    @dmsilev:
    I suppose you guys thought I was nonplussed to see those letters.

    ReplyReply
  14. 14
    Kdaug says:

    @Tom Levenson: Yup. K west of the river. Generally four letters, but not always – our local NPR affiliate is KUT

    ReplyReply
  15. 15
    Tom Levenson says:

    @Kdaug: Biker-focused programming, right?

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  16. 16
    Matt McIrvin says:

    This stuff is maddeningly difficult to explain, because it seems from any simple description as if you ought to be able to use it to make a faster-than-light telegraph, but you can’t. (The only information that can get “transmitted” is random bits, and you can only tell it happened by comparing notes conventionally after the fact.)

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  17. 17
    🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷 says:

    One of the scariest ideas in physics today is that we’re living in a false vacuum, and that at any moment we could transition into a “true” vacuum, with different laws of physics. This would result in a Vacuum Metastability Event, where this bubble of true vacuum would expand at the speed of light, engulfing everything in its path.

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  18. 18
    WereBear says:

    @Amir Khalid: Which is why I looooove me some Blake!

    ReplyReply
  19. 19
    Kdaug says:

    @Tom Levenson: Shit, I wish. Broadcast out of the University of Texas. Studio is on the campus

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  20. 20
    JPL says:

    OT MIT is having a panel on “First we Marched, Then we Ran” on Saturday. Kevin Abel the “democratic” that ran for Handel’s seat who lost in the runoff against Lucy McBath. I voted for him because of his support for a family from Somalia and his overall views on immigration. I assume being on a panel is a way to stay involved.
    If anyone in the area is going, please ask him about his support of the Problem Solvers Caucus. After Lucy won in November, he had a post about the caucus. His facebook followers (including me) were horrified. He wholeheartedly supported Lucy after his loss in the runoff, and the post came later. He lives across the street from someone I know, and if I see him, I plan on asking him myself. No labels has a big label and it’s called the former republican party.

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  21. 21
    BroD says:

    I plan to attend while simultaneously washing dishes here in Baltimore.

    ReplyReply
  22. 22
    germy says:

    @Amir Khalid:
    “Mock on, Voltaire, mock on!”

    ReplyReply
  23. 23
    germy says:

    Mock on, mock on, Voltaire, Rousseau;
    Mock on, mock on; ’tis all in vain!
    You throw the sand against the wind,
    And the wind blows it back again.
    And every sand becomes a gem
    Reflected in the beams divine;
    Blown back they blind the mocking eye,
    But still in Israel’s paths they shine.

    The Atoms of Democritus
    And Newton’s Particles of Light
    Are sands upon the Red Sea shore,
    Where Israel’s tents do shine so bright.

    ReplyReply
  24. 24
    Kdaug says:

    @🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷: …and so you don’t have to pay off your student loans? I’m not seeing the downside here

    ReplyReply
  25. 25
    SiubhanDuinne says:

    @Tom Levenson:

    There is a station in-joke ruder expansion of the acronym, but I leave that one as an exercise for the reader.

    In Canada, call letters begin with “C.” For many decades, my cousin Dave was announcer/morning host/news director for CFOS, a radio station in the lovely little Ontario town of Owen Sound.

    The repeatable local joke was that the acronym denoted “Can’t Find Owen Sound.” The ruder version was that the letters stood for “Can’t Fuck On Sunday.”

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  26. 26
    catclub says:

    I did not know that a canonical unit of x-radiation is a Crab – for the amount coming from the Crab Nebula.

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  27. 27
    PAM Dirac says:

    @MattF:

    Quantum entanglement does not violate causality. Period

    Right. And you can not send faster than light signals via entanglement (which I guess is another way of saying the same thing). Should be an interesting show. I’m interested to see if they try to make it sound like Einstein predicted these results. The EPR paper did point out that the quantum theory led to what became known as entanglement, but his thought was the result proved that quantum theory had serious problems if it led to what was obviously a ridiculous result.

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  28. 28
    Emma says:

    Mystic Mountain and the Pillars of Creation are often my screen savers, both work and home. The Hubble has gifted us with magnificent views of the Universe.

    ReplyReply
  29. 29
    🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷 says:

    @JPL:
    The Problem Solvers Caucus, aside from sounding lame and stupid, is basically No Labels. According to Wiki, they have
    equal numbers of Dems and Reps in the House and have been trying to start a similar caucus in the Senate.

    According to this WaPo piece, they haven’t accomplished much:

    House Problem Solvers Caucus has solved few problems, bipartisan critics allege

    Democrats in particular say that by supporting the group, members of their own party have given political cover to lawmakers with conservative voting records without forcing those same lawmakers to take concrete action to stall Republican legislation on health care or taxes. The caucus’s Republican members have on average voted in line with the White House’s position 93 percent of the time, according to calculations based on FiveThirtyEight’s vote tracker, with at least nine Republicans in the group doing so more than 95 percent of the time.

    You should definitely ask him why he supports such a group when you see him.

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  30. 30
    🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷 says:

    @Kdaug:
    Well, the downside is that myself and everyone I care about would be dead. But yeah, I guess I wouldn’t have to worry about my student loan anymore. Small blessings.

    ReplyReply
  31. 31
    JPL says:

    @🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷: I will. If anyone is at MIT this weekend, they need to ask him also. I don’t want him running again and won’t support him if he does.

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  32. 32
    Mathguy says:

    Of course, a couple of the really entertaining things about entanglement are the notions of quantum teleportation (yes, the “Star Trek” sort of teleportation, though only done with photons so far) and 2-for-1 information transfer (encoding two bits of information into one bit, send it and decrypt back into two). Quantum information theory and quantum computing are wonderful subjects.

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  33. 33
    WhatsMyNym says:

    @🇺🇸🌎 Goku (aka Amerikan Baka)  🗳🌷:

    One of the scariest ideas in physics today is that we’re living in a false vacuum, and that at any moment we could transition into a “true” vacuum, with different laws of physics.

    I think one of the scariest realities is that our life spans are so short compared to the timeline of the Universe, the chance of that happening during your life is basically nil.
    No money back guarantees…

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  34. 34

    @PAM Dirac:

    And you can not send faster than light signals via entanglement (which I guess is another way of saying the same thing).

    The key to why people are so bothered by it is it intuitively seems as if you really ought to be able to send information that way. We’re so used to being able to take advantage of weird physics to make useful technology that people assume that if the entangled particles can exchange information instantaneously we ought to be able to take advantage of that to make a FTL data transmission system. When we can’t, they think it’s either an excuse for physicists inability to think of a way of using it or some weird way the universe is conspiring against us. It can’t possibly be that there’s this strange phenomenon that seems like it ought to allow faster than light information exchange but that doesn’t actually work that way. People just don’t want to accept it.

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  35. 35
    West of the Rockies says:

    @MattF:

    Yeah, that’s what I was gonna say…//

    (Show off.)

    ReplyReply
  36. 36
    beef says:

    I’ve never been able to understand why people get so riled up about this stuff. An experimenter arranges the world so that there is a hidden correlation between two things. Then we measure some quantities which reflect these correlations, and presto! There is a correlation between these quantities! Of course, you can’t transfer information faster than light with these correlations. You can only arrange for the recipients of the two things to simultaneously learn some information which has been transmitted to them by whoever set up the experiment.

    But when you put it like this, you can’t make money publishing garbage popular science books.

    If you really want to cook your brain, contemplate the fact that quantum mechanical particles are indistinguishable. They do not have identity. You can say that there is an electron here and an electron there, but you can not say that _this_ electron is here and _that_ one is there.

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  37. 37
    chopper says:

    William Blake, Isaac Newton, 1795.

    damn newton had like zero body fat.

    ReplyReply
  38. 38
    chopper says:

    @dmsilev:

    and if it ever changes format, it’d be a fantastic callsign for a punk rock station.

    ReplyReply
  39. 39
    J R in WV says:

    @Goku:

    I especially enjoy reading about anything to do with space.

    Then you’re really lucky, because we are in space right now, and the physics of space are in your pocket and the palm of your hand!

    We have a bit more gravity than some locations have, and more gas around us than most locations have, otherwise, we are in space, spinning wildly, whirling around another high mass location emitting energy into — space!

    Don’t get dizzy just because you are moving thousands of miles an hour through space!

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  40. 40
    J R in WV says:

    @Kdaug:

    @Tom Levenson: Yup. K west of the river. Generally four letters, but not always – our local NPR affiliate is KUT

    But KDKA is the CBS station in Pittsburgh, PA… so not iron clad, early days were less organized.

    ReplyReply
  41. 41
    Uncle Cosmo says:

    Tom, kindly fix this para so that it makes even a smidgeon of sense:

    The program focuses on an international collaboration to test whether or not quantum entanglement (violations of what is known as Bell’s inequality — an concept that states that quantum mechanics makes predictions that are incompatible with those based on a classical understanding of how events occur.

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  42. 42
    grubert says:

    I’ve thought of quantum entanglement *and* quantum collapse as a kind of “crowd sourcing” of reality. That is, an indeterminate particle state exists in many or all possible realities until interaction with another particle causes the two particles to come to an agreement about what their shared reality is, in the form of quantum states. When huge number of interactions occur, what we consider physical reality is established.

    The “observer” of classical quantum collapse always bothered me. It shouldn’t mean a human being, but that’s what the word implies. Seems to me the observer is the rest of reality, which is itself a consensus of all the particles that have recently interacted.

    curious what Tom or others think of this interpretation.

    ReplyReply
  43. 43
    Dawg day says:

    I’ve seen the painting by Blake before, but many years ago. Does anyone else think it bears a striking resemblance to the design of the “engineers” in the movie “Prometheus”?

    ReplyReply
  44. 44
    Tom Levenson says:

    @Uncle Cosmo: it’s got at least eight full millitads of sense already. A full smidgeon will cost you extra.

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  45. 45
    PAM Dirac says:

    @Roger Moore:

    The key to why people are so bothered by it is it intuitively seems as if you really ought to be able to send information that way.

    When I was in graduate school I signed up to be in a pysch experiment for a bit of extra money. The experiment was to show you a set up and you were supposed to say how the test would turn out. All of the setups were very straightforward examples of Newton’s laws (which hits the ground faster, heavy or light ball, weight being twirled on the end of a string, what happens when you let go of the string, etc. ) You did the test and then saw how it compared to your prediction or what your intuition told you would happen. I saw the results a few years later and even at a “science” school about 60-70% of the predictions were wrong. To this day I translate “intuitive” to “wrong 60-70% of the time”. I also laugh like hell when someone tries to say Newtonian mechanics is intuitive, unlike quantum mechanics.

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  46. 46
    Bjacques says:

    Heh. I’ve got a friend who led a team in Leiden that performed the first successful experiment in quantum communications with a single bit. Cool beans.

    ReplyReply
  47. 47
    The Pale Scot says:

    Entaglement is so cool. Indicates (2 me) that what we perceive is a image/representation shell of an underlying Kernel

    ReplyReply
  48. 48
    Mick mcdick says:

    I struggled to understand Bell’s theorem through popular science explainer articles, and became convinced that either I was stupid or scientists were stupid, because I could not see the problem.
    It turned out that the explainers were just poor writers! I found an article by Professor N. David Mermin of Princeton called “is the moon there when nobody looks?” that made it quite clear why there is a problem in the Matrix. You can find it online. He introduces a little math to the explainer, which other writers seem unwilling to do. Just a grain of easy math, I promise!
    It appears that at the level of quantum, either the rules of math break down or causality deserts the ship. Once I digested Mermin, I was like, “WTF!” Prof Mermin also wrote an excellent book explaining special relativity, and it is also awesome and clear. Can’t recommend Mermin too much, he is the boss.

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  49. 49
    Balconesfault says:

    @J R in WV: And WOAI is just down I35 from the aforementioned KUT in San Antonio.

    ReplyReply
  50. 50
    Arisian says:

    I watched this show on PBS last night, and I was dismayed to hear, in the explanation of quantum computing, that a quantum computer “could solve the traveling salesman problem much faster than classical computers”. Now, that’s a kind of vague claim in English, but there is a general impression among many with just enough knowledge to be dangerous about this area that quantum computers will be able to quickly solve problems that we know to be intractably hard with classical machines (the traveling salesman problem is one example). To date there is no support for this belief, and many if not most experts believe it isn’t likely to be the case. There are a few problems for which we know fast quantum algorithms and don’t know any fast classical algorithms, but none of those is the same type of hard problem as the traveling salesman problem. To me, NOVA’s presentation of this was quite misleading, a non-expert would likely conclude that we are sure that quantum computers will be able to do all sorts of super fast calculations that we just can’t afford to do on classical machines.

    This was followed by the main discussion around Bell’s theorem, and I’m no expert on that. But after what I had just heard, I took everything they said with some grains of salt. I’ve seen this before on NOVA. In areas I actually know something about, they take things that might possibly end up being true and would be really cool if they were, and present them as if they were the current scientific consensus. I wish they would quit doing that.

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