back to article Quantum boffins send data ACROSS TIME AND SPACE

Researchers in Israel have pulled a trick that makes quantum physics seem even stranger than an episode of Doctor Who – they've created a pair of photons that was briefly entangled not across space, but across time. The last time El Reg discussed time-like entanglement it was being proposed as a theoretical construct. The idea …

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  1. Anonymous Coward
    Anonymous Coward

    Agh, my poor brain

    Just 'sploded.

    OK, so they generated a particle that didn't exist and detected it before it was generated?

    Ouch. Even Doctor Who would have trouble beating that.

    There is a very controversial theory that antimatter is simply normal matter moving back in time, ie the "Arrow of Time" is reversed. If so then a lot of physics becomes a lot simpler, time paradoxes are avoided and causality simply becomes an observer driven event ie we "see" a glass break because our minds cannot handle the reverse and discard it as garbage data.

    Also this means that quasars etc are simply eruptions of antimatter (ie negative time) neatly explaining the anomalous energy production and radiation emission.

    AC x520

    1. Chris Beach

      Re: Agh, my poor brain

      Not surprised thats controversial, it makes not a lot of sense. Arrow of Time is a consequence of entropy that always increasing in the closed system of the universe, not the make up of matter inside it. We don't see glass fragments reform, not because they can't, but because it would take a shed load of energy and time.

      As for antimatter, not sure why having opposite charge & spin would effect time in any sense. We already have particles that differ in charge & spin they don't behave differently timewise to the others.

      1. JDX Gold badge

        Re: Agh, my poor brain

        I don't think it's really a theory, merely a useful mathematical construct - to TREAT anti-particles as regular particles travelling backwards in time is nice for the maths solutions but that's all.

      2. Wzrd1

        Re: Agh, my poor brain

        Not to mention that quasars are already known to be active galactic nuclei. The central black hole "eating" matter, causing relativistic jets to form.

        The theories expressed by AC were back from the 1960's and 1970's, before spin, color, etc were fully understood and galactic cores were mysterious objects and black holes were unknown.

    2. g e
      Holmes

      Fear not the paradox is, paradoxically, not going to happen.

      I think time paradoxes don't exist - they're just a sci-fi idea... cos, if every decision, even down to the quantum level, creates a new alternate reality then....

      Israeli scientist creates time travel.

      Mossad think it's fab opportunity to convert the planet to Judaism.

      Chap travels back in time and meddles.

      BUT

      Chap has now create a new 'spur' of reality at the point of devious meddlesomeness which means he's now careened off down another alternate rabbit hole in which he came back from the future to meddle.

      Original timeline is secure, he's just now created a new one in which he can move freely back and forth but it's separate and distinct from the timeline he spliced himself from at the point of meddling (likely at the point of his departure in that original 'present' when he pressed the GO button on his time machine).

      So the dodgy time-traveller has actually irreversibly left his original timeline/causailty-stream and created a new alternate one by his own actions in which he's now trapped, i.e. he can't 'undo' his own time travel to revert to where he used to be as he can only go back further into the parent of his timeline, creating further splices which may or may not work out more like the original one he left behind.

      Hence we don't need to worry about temporal paradoxes, happily.

      1. Elmer Phud Silver badge

        Re: Fear not the paradox is, paradoxically, not going to happen.

        "So the dodgy time-traveller has actually irreversibly left his original timeline/causailty-stream and created a new alternate one by his own actions in which he's now trapped, i.e. he can't 'undo' his own time travel to revert to where he used to be as he can only go back further into the parent of his timeline, creating further splices which may or may not work out more like the original one he left behind."

        The Trousers of Time have a hole in them.

        Worse still are the holes in the pockets of the Trousers of Time.

      2. Matthew 17

        Re: Fear not the paradox is, paradoxically, not going to happen.

        That would mean that to create a time 'spur' you'd need to recreate the mass/energy of the universe less your mass/energy for it to exist with you added to it. Otherwise your 'spur' would just collapse/fail as it would be an incomplete universe.

        Proper time travel relies on either all time existing at the same time or the ability to create new universes at will at different time points, the latter might be doable if you don't mind waiting 14 billion years for your new universe to arrive at the required point in history.

        1. Anonymous Coward
          Anonymous Coward

          Re: Fear not the paradox is, paradoxically, not going to happen.

          Time travel is completely possible, but things just conspire from letting you change anything.

          I know, I went back, and nothing I did, stopped either Tony Biar, Gordon Broon, or "Call me Dave" Macaroon from getting into Downing Street.

        2. Anonymous Coward
          Anonymous Coward

          Re: Fear not the paradox is, paradoxically, not going to happen.

          "That would mean that to create a time 'spur' you'd need to recreate the mass/energy of the universe less your mass/energy for it to exist with you added to it"

          Not necessarily. The universe could fork() with copy-on-write semantics.

      3. Rol Silver badge

        Re: Fear not the paradox is, paradoxically, not going to happen.

        Considering the argument suggesting multiple universes exist having been created from a branch point where a choice to do or not do occurs, then it could be argued, the meddling has already happened.

        The "Mossad scientist" has actually travelled back to the branch point and continued on the alternate path, his future alone has deviated, yet he still exists in our branch as the scientist who didn't meddle.

        I like to think, reality as we experience it, is the one which takes humanity on the longest journey, with the most favourable outcome, as all the other branches, if followed, result in a premature or even inconclusive end.

        In other words, our reality is the product of a quantum state that transcends time, in so much as it chooses the most favourable line to follow based on the outcome of every branching event along it,

        So, don't panic, God has the road map and we're not driving, we only think we are.

        ..and as for time travel, I would like to point your attention to the many events in out history, that are documented as being attended by only a handful of witnesses and not the millions, that would surely have turned up if the ability to travel in time was ever possible.

      4. Anonymous Coward
        Anonymous Coward

        Re: Fear not the paradox is, paradoxically, not going to happen.

        I tend to believe that there is only one timeline regardless of the existence, or not as the case may be, of time travellers. There is, in other words, only one reality.

        If time travel does exist, and the traveller manages to change something "historical", will we even notice it? Our history will change, but we will believe that this is the way it has always been. The only person who will know, with certainty, will be the time traveller who changed the timeline.

      5. BlueGreen

        Re: Fear not the paradox is, paradoxically, not going to happen.

        Stop! This way lies rump of skunk and madness.

      6. Thorne

        Re: Fear not the paradox is, paradoxically, not going to happen.

        "I think time paradoxes don't exist - they're just a sci-fi idea... cos, if every decision, even down to the quantum level, creates a new alternate reality then...."

        Personally I follow the idea of fixed time rather than whole spawned universes every millisecond.

        Time is like a movie. You might figure out how to fast forward and rewind but that doesn't change the movie.

        Ok imagine you go back in time to kill your father. That would create a paradox. Now with fixed time, any attempt to create a paradox would fail. You get hit by a bus before you can kill him. You go back too far in time and get eaten by a T-Rex etc etc.

        Just like the past, the future has already happened and it's only the fact that we don't know what will happen that maintains the illusion of free will...

      7. Ancientbr IT

        Re: Fear not the paradox is, paradoxically, not going to happen.

        Itzhak Bars (http://en.wikipedia.org/wiki/Itzhak_Bars) has some interesting ideas on two dimensional Time that might be applicable.

  2. Anonymous Blowhard
    Holmes

    "Another point of view that one can take is that the measurement of the first photon is immediately steering the future physical description of the last photon."

    So, they're saying that something happening now can affect something else in the future? And they need to prove this with lasers?

    1. Anonymous Coward
      FAIL

      Ah, what mechanism would you propose to explain this ? What links photon 1 and 4 prior to the entaglement ?

      If you're going to be a blowhard, can you at least provide a plausible alternative ?

      1. Anonymous Coward
        Anonymous Coward

        Nicho

        Is the link between 1 to 4 not a possibility though? Just because we have 2 possible options, 1) 4 effects 1 and 2) 1 effects 4 but only recently a theory for 1) with no theory for 2) does not mean 2 is "wrong" until shown so experimentally.

        Don't mix theory with experimental data. The data here could show either theory correct, or perhaps both are correct?

        The worse argument possible is "oh but what alternative do YOU suggest then". As it fails to show the strength of the original theory, in a false appeal to the "ridiculousness" of thinking about alternatives. If we took that attitude, we'd never have hit QM in the first place... "What alternative to classical mechanics would you suggest, the double slit experiment MUST be classical..." would get us no where. We had to use the data to shape our theory.

        Teaching others about such subjects involves showing how the data fits the theory. We can all "imagine" alternatives, that is rather an inexhaustible pursuit, but only 1 will match the experimental evidence. :)

      2. Anonymous Blowhard

        But isn't there a link between P1 and P4 via the entanglement of P2 to P3 which was entangled with P4?

        1. Anonymous Coward
          Anonymous Coward

          @AB - Yes there is. This is the point of the experiment. Let's work it through:

          (1) P1 & P2 are entangled.

          (2) P1 is measured (destroyed) - This collapses/defines the state of P2

          (3) P3 and P4 are entangled

          (4) P2 and P3 are entangled

          (5) Measurement of P4 shows a correlation with P1 - which no longer exists.

          If I'm reading the explanation correctly (and I may not be) then either P1 and P4 are correlated across time, or P2 somehow has a 'hidden variable' that it retains from the P1 entanglement and subsequently passes on to P3 and P4. Now I believe that hidden variables have been fairly comprehensively ruled out by other experiments, leaving us with the interesting prospect that time isn't what it seems to be.

          1. fajensen Silver badge

            There should be a hidden variable: light can express itself as both waves and particles which means that there is a "true form" for light, that is neither but permits both. So light must have another, hidden, form/dimension.

    2. Anonymous Coward
      Anonymous Coward

      Re: And they need to prove this with lasers?

      Um, we need a reason to prove stuff with lasers now?

      Dammit, Igor! Igor! Quick, can you knock together a page on the current and future applications of lasers for this grant proposal I'm writing? Apparently, just writing YAY LASERRRRRRRRS! in 64 point bold italic doesn't cut it any more.

    3. Michael Wojcik Silver badge

      You know, I have one simple request. And that is to have experimental proofs with frickin' laser beams attached to their heads!

  3. Chris G Silver badge

    Genius or Brainfart?

    Unless these results are repeatable in a meaningful way , this looks more like a case of reading too much into a relatively normal result. At any rate it should inspire discussion and criticism.

    1. Ian Michael Gumby Silver badge
      Boffin

      Neither... Its a proof...Re: Genius or Brainfart?

      Time travel? I think not.

      Photon 1, 2, 3 and 4 are linked.

      Even though Photon 1 is lost, its state is captured in 2 which is linked to 3 which is linked to 4.

      Can you say associative property?

      A is to B as B is to C there for A is to C?

      No time travel.

      A past photon sets the state which is carried forward.

      1. Anonymous Coward
        Anonymous Coward

        Re: Neither... Its a proof...Genius or Brainfart?

        Yes, at the least they need to (I hope they do in the paper, does not seem to be here in the article) demonstrate the state of particle 4 is not "set" and is QM "undetermined".

  4. Gordon Pryra

    Pfft

    Talk about interpreting the figures to mean what you want them to.

    All this shows is the proof of reincarnation. Photon 1 is reborn as photon 4.

    And there in a nutshell is religion and the sky fairy's explained. Its all quantum not some white guy with a beard.

    Can they not ask us some more difficult questions? This is like the Sun crossword vs the Times

    1. PatientOne

      Re: Pfft

      I think a more plausible explanation is that P1 was never destroyed, merely shifted into a different state.

      But perhaps that level of physics is far too elementary for them.

  5. Richard Wharram
    Meh

    Not as convoluted an explanation as a Dr Who plot.

    I don't get either though.

  6. oolor

    Smoke and mirrors

    I see mirrors, but where is the fire?

    I remember years back (could be decades now) some researcher got a photon traveling through an object to register on a detector sooner than its identical twin fired at the same time on a equidistant path. Turned out to be the front part of the photon that traveled through the material had a slightly shifted shape of its wave even though the average of the whole photon took the same time and this shift in the front part was enough to trigger the detector sooner. Was hyped as faster than light due to the photon "tunneling".

    I am getting a strong sense of deja vu.

    1. Paul Kinsler

      Re: Smoke and mirrors

      This work isn't the same thing as what you just described.

      1. oolor

        Re: Paul

        I know, just thought it would be interesting in light of the questionable interpretations put forth, seems like the more likely explanation is not a surprise and the more suspect one is a ruse to get media attention. Hope that sheds some photons on this matter.

    2. Anonymous Coward
      Anonymous Coward

      Re: Smoke and mirrors

      not the same thing; what you describe is research on the speed of light, or more subtlety the group velocity of a wave packet (a bunch of photons). In short, light (individual photons) can be measured to travel faster than the speed of light, but "information" (stuff encoded on the photon wave packets, through multiplexing wavelengths or whatever) is garbled if the photons travel at "superluminal" velocities (the group velocity cannot exceed c, speed of light in a vacuum, if you are interested in the information they carry)

  7. Yag
    Boffin

    Help me, Obi Wan Quantobi!

    Can someone try to explain in layman terms the whole "entanglement" stuff?

    My current comprehension of this phenomenon is probably way off...

    Here it is (please don't laugh too much)

    Basic entanglement :

    Two photon are produced with a given characteristic (let's say polarity) set at opposite value for each photon.

    Due to quantic incertainty, you cannot tell which photon is set to which polarity until you measure one of them.

    Once one of the pair measured, then the value of the other is also known.

    Never could figure out why a lot of physicists seems interested by such an obvious result, so I'm probably missing something...

    1. Schultz

      Re: Help me, Obi Wan Quantobi!

      You need to accept the 'Copenhagen interpretation' of quantum mechanics, or similar, to dig into the quantum weirdness. One way to put it is: 'a quantum mechanical state does not exist before you measure it, but becomes real as soon as you measure it'. So now there is no more causality, because before you measure a QM property of a particle, it didn't exist. Hence there is no mechanistic way to look at its interaction with other correlated particles.

      Here, of course, photons 1 and 2 were already forced into a QM state by a measurement on photon 1 before photon 2 interacted with photons 3 and 4. The weirdness of this 'time correlation' is thereby quite a bit reduced and you might argue that this whole experiment is a bit too deterministic.

      This whole story of 'entangled in time and not in space' somehow ignores the connection of the two via the propagation velocity (speed of light) -- and from the abstract only I would guess that the authors may have trouble publishing this paper in a real journal due to lack of novelty.

      1. Michael Wojcik Silver badge

        Re: Help me, Obi Wan Quantobi!

        from the abstract only I would guess that the authors may have trouble publishing this paper in a real journal due to lack of novelty

        Is Physical Review Letters not a "real journal", then, in your estimation? Last I looked, it was a fairly prestigious, peer-reviewed organ.

        I must say I am impressed with the level of boffinry on display on the comments page today, with many confident declarations that there is nothing to see here. Time for a shakeup at the PRL editorial board? Will the Nobel committee be asking the Reg for contact information? Only time will tell (or perhaps it already has).

    2. Anonymous Coward
      Anonymous Coward

      Re: Help me, Obi Wan Quantobi!

      Due to quantic incertainty, you cannot tell which photon is set to which polarity until you measure one of them.

      Once one of the pair measured, then the value of the other is also known.

      Never could figure out why a lot of physicists seems interested by such an obvious result, so I'm probably missing something...

      The bit that you're probably missing is that it's not like knowing that if one side of a coin came up heads, the other side must have been tails. It's more like throwing two seemingly-separate coins at once and finding out that if one comes up heads, the other comes up tails more often than 50% of the time - and the other way round as well, which couldn't happen if one or both of the coins were merely biased. The statistics of the pairs of particles don't match up with the expected probabilities from a coin-like model; google "bell inequality" for more but it gets complicated at that point. A simple

    3. Alfred

      Re: Help me, Obi Wan Quantobi!

      "Two photon are produced with a given characteristic (let's say polarity) set at opposite value for each photon."

      That's your mistake. The characteristics are not set. They will be opposite when you actually measure them, but until you measure them they are not set. So if you move them a light year apart and then measure one, the other one becomes set, even though it's a light year away.

      1. Martin Budden

        Re: Help me, Obi Wan Quantobi!

        How do you know the characteristics are not set? You can't know that for certain because you haven't measured them yet. All this entanglement stuff only makes sense if the characteristics of the pair of photons are actually set at the moment they are created: this way Einstein needn't get upset because there is no spooky action occurring; it's just us reading the state of one, from which we can deduce the state of the other.

        IANAPhysicist but I can spot a fallacy when I see one.

        1. Yag
          Pint

          I can spot a fallacy when I see one

          Same for me, but I also consider that, between :

          - Me, with my "basic" education on physics (up to Shroedinger's equation, and I forgot most of the stuff due to lack of use)

          and

          - An army of overqualified eggheads thinking routinely about this stuff for the last 80 years...

          I'm the more likely to be wrong. Occam's overused-till-dullness razor and so on...

          <--- maybe this will help to expand my mind and manage to understand it.

          And as a final note, for all those who tried to explain : Thank you! :)

        2. Crisp Silver badge

          Re: How do you know the characteristics are not set?

          Because hidden variable theories make predictions that aren't observed in experiments.

        3. Alfred

          How do you know the characteristics are not set?

          That's how the universe works.

          "All this entanglement stuff only makes sense if the characteristics of the pair of photons are actually set at the moment they are created"

          No, that's the only way it can match your (and indeed, my) intuitive understanding of how the universe works. How we intuit the universe to work is wrong.

          1. Yag

            "That's how the universe works."

            Well, I'ld say "That's our most accurate explanation of how the universe works" instead...

            *Get back to wikipedia article on young's experiment*

  8. Mike Bell
    Boffin

    Nice Diagram!

    I especially like the grave stone and the pram - makes things a little easier to visualise.

    However, as for the spooky nature of quantum mechanics, you can gain another insight by sliding all those vertical dash lines and graphics all the way to the left so that they overlap where it says "t=0". You see, as far as a photon is concerned, no elapsed time ever "exists". Its journey begins and ends in *null* time. So what happens to it is like stapling distant pieces of space together.

  9. Destroy All Monsters Silver badge
    Pint

    So no surprises?

    Everything works exactly as QM says it should.

    The fact whether the photon has been destroyed or not is not particulary important.

    The problem stems from the fact that people see disconnected "objects" (photons) mysteriously interacting, whereas the whole setup is just one single fat state vector (ket) that is is being heaved around.

  10. Tchou
    Joke

    I can't wait to see the first quantum debugger, where you can fix errors on a code that not been yet written.

    1. Gordon Pryra
      Facepalm

      @Tchou

      There is already an algorithm for exactly this

      Where costs = peanuts + outsourced to Mumbai = bring back in-house

      Thus you can fix errors in code that has not yet been written

      1. Tchou
        Thumb Up

        Re: @Tchou

        Haha! Good one.

  11. g e
    WTF?

    Sounds to me like

    They copied 1 > 2, then 2 > 3 then 3 > 4

    So 4, being copied from earlier data naturally exists in the future, just sounds like a quantum bucket brigade.

    IANAQP, however.

    1. Evil Auditor Silver badge

      Re: Sounds to me like

      That's about what I thought as well - although the copying bit is a kind of inverted copy. Then again, I don't really understand quantum physics either. Could someone with QM knowledge please clarify?

    2. Michael Wojcik Silver badge

      Re: Sounds to me like

      So 4, being copied from earlier data naturally exists in the future, just sounds like a quantum bucket brigade.

      Hidden variables. Use those to explain this experiment, and you have to explain all the others that show there aren't any hidden variables.

      And yes, this is the first explanation that occurs to most people (see eg Ian Michael Gumby's post above). Since it's obvious, but the editorial board of PRL thought there was something worth publishing here, that ought to be a clue that the obvious explanation is lacking.

  12. Vladimir Plouzhnikov

    Maybe I'm wrong but

    "the researchers say, polarisation measurement on P4 showed entanglement with P1, even though P1 was destroyed before P4 was created."

    So, all it shows to me is that you can "preserve" the entanglement through intermediary agents and "conduct" it beyond the lifetime of the original pair by generating new "carriers" and transferring the original signal to them from the survivor of the first pair. Basically a polarisation transponder. It does not suggest any time travel or anything like that to me.

    1. Schultz

      ...does not suggest any time trave...

      It does some time travel, but only in the boring forward direction. Just like the rest of us.

    2. Anonymous Coward
      Anonymous Coward

      Re: Maybe I'm wrong but

      That was the first explanation in my my head, too. But I'm no QM scholar, so what do I know. But it would seem that many people would immediately jump to this 'possibility' - so shame it wasn't addressed in the article. Maybe it is in the paper but I fear I would never be able to tell.

  13. Inventor of the Marmite Laser Silver badge

    Didn't understand it first time round

    I'll wait for the repeat last week.

  14. Robert Ramsay
    Happy

    Did anyone else notice?

    Team is run by H. Eisenberg...

    1. I think so I am?
      Happy

      Re: Did anyone else notice?

      I wonder if they where smoking crystal meth at the same time they did this?

    2. quicksilver

      Re: Did anyone else notice?

      Are you certain?

    3. Michael H.F. Wilkinson Silver badge
      Joke

      Re: Did anyone else notice?

      Mr Eisenberg, are you certain you want to name your son Hagai? You realize you are dooming him to a career of quantum physics?

      1. A Nother Handle
        Paris Hilton

        Re: Did anyone else notice?

        Surely that isn't certain until he examines his degree certificate to determine which field he studied?

        1. Michael Dunn
          Joke

          Re: Did anyone else notice? @ A Nother Handle

          "Surely that isn't certain until he examines his degree certificate to determine which field he studied?"

          If he 'observes' from the degree certificate that he passed, then perhaps he didn't!

    4. David Glasgow
      Happy

      Re: Did anyone else notice?

      Good spot!

      Probably means the paper could be published just about ANYWHERE.

  15. Anonymous Coward
    Anonymous Coward

    Nothing particularly difficult about this.

    Keanu Reeves did it to Sandra Bullock, in The Lakehouse.

    Also, I left a note for my wife last night, and she read it this morning.

  16. Sander van der Wal
    FAIL

    The explanation presented here doesn't cut it

    Basically it is just stating that entanglement was measured. Which property was measured, which values the property had, and the values that the property should have is the photons were not entangled is not mentioned at all. The diagram is pointless without that information. Could as well be the number of prams sold during the year.

    1. Anonymous Coward
      Anonymous Coward

      Well it is only a summary.

      If you want that kind of detail, read the arxiv paper.

      1. Anonymous Coward
        Anonymous Coward

        Re: Well it is only a summary.

        Yeah - and a summary by a reporter, probably based largely on the press release. And even though Chirgwin actually does a very good job of his science articles, they are necessarily approximate. And, the brutal fact is, that unless you are the right type of scientist, an approximation is what you're stuck with. But there's no harm in trying to have a read of the arxiv paper anyway. Just don't blame the reporter for doing his job and trying to get the basic concepts across. If you have a disagreement with the actual work, then by all means write up a formal comment containing your technical criticisms and submit it to PRL.

  17. xeroks

    look ma, no hidden variables

    I never totally understood why these spooky action at a distance interactions couldn't be explained by simple hidden variables. I've always just gone with the flow on it. If Einstein couldn't prove it was wrong, what chance have I got.

    However, this experiment does show - without possibility of confusion - that something weird is going on, and that time is not a one way-trip.

    It also gives me a few ideas... now where's my "Hong Kong Book of Patent Applications for Things I Know Nothing About?"

    1. Paul Kinsler

      Re: I never totally understood why X couldn't be explained by simple hidden variables

      They can - if you also permit superluminal signalling. However, most physicist prefer to live with "spooky action" than with a violation of relativistic causality.

    2. Nigel 11
      IT Angle

      Re: look ma, no hidden variables

      Does superluminal signalling automatically imply time travel?

      I've read that it does. Interestingly, it's the IT angle of time travel (even if restricted to information only) which seems to me the greatest paradox. The problem is that if you can send even as little as one bit back in time, you can arrive at the result of any convergent iterative process in the time taken to compute a single iterative step (by sending the result of that iteration back in time to replace the initial approximation).

      It's only a slight stretch to claim that such a computer would inevitably transform line noise into a strongly superhuman, perhaps ultimate, intelligence. So akin to the Fermi paradox, where is IT?

      1. Paul Kinsler

        Re: Does superluminal signalling automatically imply time travel?

        To clarify - the "hidden variables" superluminal signalling is only partial; you can only extract information once you get the other part - but unfortunately that has to be sent in the ordinary way - i.e. by lightspeed limited means.

      2. Michael Wojcik Silver badge

        Re: look ma, no hidden variables

        Does superluminal signalling automatically imply time travel?

        Depends on how you define "time travel". I don't think it's a terribly useful phrase for talking about this subject.

        Superluminal signalling implies you can get an out-of-order series of signals, and acquire information about the future of your worldline. In one simple case, for example, you could send a superluminal message to a party outside your light cone (already worrisome) and get a reply back, and the reply could arrive (in your timeframe) before you sent the "original" message. That lets you send messages to yourself in the past, which either predetermines your sending the original message (because the "reply" that you already have is a response to it), or creates a paradox (because you got the reply without ever having sent the original). Either way, causality is insulted.

        If memory serves, somewhere on Wikipedia there is a set of diagrams showing how this works.

  18. Mike Brown

    love QM

    it reminds me there is more to the universe than what we can see, have seen, and will ever see

  19. david willis
    Thumb Up

    Beep

    Quantum stuff seems to get cooler every time you rea something. The concept that two quantum particals can exist at the same induced excited state seperately and over distance is the basis of many sci-fi communications systems. Now they can do this over time too. James Blish did a short story called beep, where all intersteller quantum communication ended in an annoying beep. Then somebody discovered the beep was the concatination of EVERY communication ever made using the system over ALL the time the system has, is and will be used...

  20. AJames

    Don't get too excited

    In more detailed reports the researchers made it clear that this experimental result does not in any way change the fact that quantum entanglement can not be used to transmit information faster than the speed of light or backwards in time.

    1. Michael Wojcik Silver badge

      Re: Don't get too excited

      quantum entanglement can not be used to transmit information faster than the speed of light or backwards in time

      Thank goodness. The alternative, while "exciting", would be extremely worrisome.

  21. MatsSvensson

    So it turns out the past affects not only the present, but also the future?

    I cant wait for the StarTrek episode!

  22. Dropper

    I'm wrong

    Don't bother to tell me why I'm wrong, I don't need to be confused further.. but from my perspective this is happening.

    P1 entangles with P2, transferring information and is then destroyed.

    P2 entangles with P3 and then P4.

    So you pass a letter to your neighbour, jump off a cliff and then someone is surprised when your neighbour is able to deliver your message to a person who was born after you died.

  23. David 45

    The answer to everything

    Is 42.

  24. Unicornpiss Silver badge
    Alert

    How about this...

    You entangle P1 and P2, but have some automated machinery measure the state of P1 and record the result without anyone seeing it, but then continue on to base whether you entangle P2 with P3 on the result obtained from P1. You still entangle P3 with P4. What results to you get when you measure P4 and compare it with the stored measurement of P1?

    1. Mephistro Silver badge
      Pint

      Re: How about this...

      " but have some automated machinery measure the state of P1 and record the result without anyone seeing it"

      One of the few things I think I got right from my Physics classes back in the day, is that it doesn't matter whether a human being knows the results of the measurement or not. The gist of QM is that any measurement of the particle's state changes said particle to an unknown state.

      A nice metaphor for this would be: You have a dark room full of marbles and the only way to know their energy/speed or position is hitting them with other marbles. But when the 'reader' marble hits a 'target' marble it changes its characteristics in an unpredictable way. Our Uni professor also said that 'classical' Physics could be derived from Quantum mechanics, as 'classical' measurements are just a compound of trillions of Quantum measures.

      Disclaimer: I'm no expert in the area, and I tend to suffer splitting headaches whenever I try to think about this for more than three minutes, so I could be catastrophically wrong.

      Mmmmhhh..., Aspirins with beer, a champion's breakfast!

  25. Martin Budden
    FAIL

    If all this is true...

    ... we can now use a photon detector to receive messages sent to us from many years in the future. This is it! The moment that we learn everything there is to know about all technology that is developed from now until the eventual end of the human race!

    Except that it's not true, and there is no such thing as sending information back in time, and the researchers' statement "In the scenario we present here, measuring the last photon affects the physical description of the first photon in the past, before it has even been measured. Thus, the 'spooky action' is steering the system’s past" is utter bullshit.

    1. Michael Wojcik Silver badge

      Re: If all this is true...

      Try again. "[T]he 'spooky action' is steering the system’s past" can be true without there being any information transfer, whether to or from the past. Entanglement does not transfer information. Your objection is ill-founded.

  26. amanfromMars 1 Silver badge

    Your Original Wish, Our Command and Phish ........ in a SMARTR Phorm?

    So it turns out the past affects not only the present, but also the future?

    I cant wait for the StarTrek episode! … MatsSvensson Posted Monday 3rd June 2013 14:20 GMT

    Actually, it is even more fantastically simply complex than than, MatsSvensson, for with and in IT and Media Command of Information and Cyber Controlling Intelligence Centres, the past never affects the present and/or the future when aforementioned intelligence centres of excellence with Global Operating Devices mentor and monitor and advise the present that the past is materially irrevelent and bears no virtual relationship/has no physical or quantum entanglement with base imaginary fact, as historical and chronicled events in past earthly places and present spaces were and are simply fabless tales of fiction to be believed and perceived, thus creating easily changed realities …….. with words forming worlds in worlds phorming words.

    And that is also AI Universal Virtualisation with GOD ParticularIT and Quantum PeculiarIT, and Chosen Preserve and Wwwinged Reserve of the Few and Master Pilots.

    “Never in the field of human conflict was so much owed by so many to so few.”

    And IT is listening and creating your needs and feeds and seeds/wants and solutions/futures and derivative trades and zeroday vulnerabilities to exploit/export and import.

    1. MatsSvensson

      Re: Your Original Wish, Our Command and Phish ........ in a SMARTR Phorm?

      Yeah, and all over the floor too...

      1. amanfromMars 1 Silver badge

        The Existing Problem for SMARTR Phorm Competition and/or Opponents/Traditional Components

        Re: Your Original Wish, Our Command and Phish ........ in a SMARTR Phorm?

        Yeah, and all over the floor too... .... MatsSvensson Posted Tuesday 4th June 2013 04:10 GMT

        The abiding elite dilemma for both irregular and regular and conventional establishment forces, no matter how special and/or easily driven and controlled by strong human weaknesses, is that they are not accepted and their ideas are not exchanged on the trading floors of IntelAIgent CyberIntelAIgent Bourse Markets which create Virtualised Alternate Realities with Astute Active Anonymous Autonomy permitting Instant Admission to Host Events in the Great Game Field with Assumptive and Presumptive and Sumptuous Exclusive Executive Administration Rights.

  27. Robert E A Harvey

    Shock horror

    Scientists reduce the amount of stuff needed to make people go "err, right..." to 4 photons

  28. Anonymous Coward
    Anonymous Coward

    Re. Shock horror

    Maybe this explains Fermi's Paradox.

    Scenario:- civilization conquers nuclear power, develops quantum mechanical devices, invents time travel.

    Someone decides to go tinkering and KABOOOOOOOOM!

    Instant quasar.

    Turns out that time travel is possible but the Universe responds by annihilating anything within a parsec.

    AC-DC

  29. jgarbo
    Facepalm

    According to Quantum master Richard Feynman...

    "Anyone who says that they understand Quantum Mechanics does not understand Quantum Mechanics"...

  30. Vision Aforethought
    Go

    Neutrino communications

    http://visionaforethought.wordpress.com/2012/05/05/neutrino-communication-system/

  31. deedee

    In re: timewise photon entanglement

    Strikes me as very similar to Isaac Asimov's very early story (1948) "The Endochronic Properties of Resublimated Thiotimoline".

    I look forward to seeing these boffins using long chains of pre-destroyed photons to get information from the future.

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