Catch up on stories from the past week (and beyond) at the Slashdot story archive

 



Forgot your password?
typodupeerror
Compare cell phone plans using Wirefly's innovative plan comparison tool ×
Australia Science

The Quantum Experiment That Simulates a Time Machine 139

KentuckyFC writes One of the extraordinary features of quantum mechanics is that one quantum system can simulate the behaviour of another that might otherwise be difficult to create. That's exactly what a group of physicists in Australia have done in creating a quantum system that simulates a quantum time machine. Back in the early 90s, physicists showed that a quantum particle could enter a region of spacetime that loops back on itself, known as a closed timelike curve, without creating grandfather-type paradoxes in which time travellers kill their grandfathers thereby ensuring they could never have existed to travel back in time in the first place. Nobody has ever built a quantum closed time-like curve but now they don't have to. The Australian team have simulated its behaviour by allowing two entangled photons to interfere with each other in a way that recreates the behaviour of a single photon interacting with an older version of itself. The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes. Interestingly, the results are entirely compatible with relativity, suggesting that this type of experiment might be an interesting way of reconciling it with quantum mechanics.
This discussion has been archived. No new comments can be posted.

The Quantum Experiment That Simulates a Time Machine

Comments Filter:
  • No Steins;Gate [wikipedia.org] green bananas for me! Tuturu!
    • by Anonymous Coward

      Oh c'mon! You can still make good gel'nanas.

      Besides, this is probably what SERN wants us to believe.

    • by Anonymous Coward

      Tuturu!

  • by the_skywise ( 189793 ) on Thursday January 29, 2015 @10:54AM (#48931365)

    > The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes.

    There is no time travel citizen! Go on about your lives.

    Meanwhile the military starts researching chrono-troops. Because, you know, Australia has always controlled the world with its benevolent Empire...

    • Or if you do go back in time, your grandfather will kill you first, so he can tell those tales at nauseum on how he fought off a mad man at nauseum, which enrages you so much that you just want to go back in time and kill him.
         

      • by psmears ( 629712 )

        at nauseum

        I think you possibly mean ad nauseam [cambridge.org]?

        • Are you implying that my Open Source Grammar and Spell checker is faulty?

          • Meh, just go back in time and get Cambridge to accept "at nauseum" as the approved version.

            That's how nerds will win the internet in the future. :)

            • by grcumb ( 781340 )

              Meh, just go back in time and get Cambridge to accept "at nauseum" as the approved version.

              That's how nerds will win the internet in the future. :)

              What makes you think we haven't already done that with ad neaseam?

              Sincerely,
              Bruce Hecklesby
              Chairman,
              International Time Travelers for Proper Latin Spelling

              • by grcumb ( 781340 )

                What makes you think we haven't already done that with ad neaseam ?

                Wait - I'm confused. Have we renamed it ad neaseam yet? Or is it still nauseam?

                Bruce

        • at nauseum

          I think you possibly mean ad nauseam [cambridge.org]?

          It was at the Battle of Nauseum, in Sicily. The Jerries had the drop on us, but old Birdy took up the Enfield and went over the top for God and Country, and don't you know the regiment followed the bloody old blighter... and blah blah blah blah blah blah blah blah blah

    • I, for one, do NOT welcome my "shrimp on the barbie" eating, "G'day mate" saying, Australian overlords!
  • by rossdee ( 243626 ) on Thursday January 29, 2015 @10:56AM (#48931375)

    You don't need grandfathers to have paradoxes

  • by Thanshin ( 1188877 ) on Thursday January 29, 2015 @10:58AM (#48931385)

    This isn't news. They already did the same experiment in January 2015.

  • by Anonymous Coward on Thursday January 29, 2015 @11:13AM (#48931471)

    Time travel is possible but not in the way you think about it. It exists going backwards but is tied to alternate realities, or tied to multiple universes. When the quantum particle loops back on itself, it's going back to an alternate universe which is similar but slightly different. The farther it loops back on itself the closer the alternate universe is similar to ours. This is because of the Big Bang, and we all originated from the same point in space. if you keep going farther back eventually all universes converge. On the flip side, the farther ahead in time one travels, the more random a universe. The present time is the only constant

    If the particle were to kill itself, it would only kill the version in the new universe it is in, not the original from which it originated. One can never travel back in time in their own universe, and if they travel forward, it will never be their original universe but a similar one, and the farther in time they go forward, the more different the universe would be from their original one.

    The universe and everything we know follow a set of laws, and it was designed in a way that we could not alter our own universe. At least past universe. However, you could change your original future universe by gathering knowledge from other universes and returning at the exact moment in time you left if you could find the correct signature of your own original universe before you traveled in time. So Leave original universe, gather info, return to exact universe using a signature you already know about gathered at the exact moment you left. If you return a few seconds later, your signature would be off as things could have happened different in those few seconds somewhere in your universe, and would not be your true original universe.

    Obviously we have a long way to go to be able to accomplish such tasks, but that's the general theory, and with this article this is the beginning steps of time travel.

    Yes, I have traveled back in time already and am here in an alternate universe. However I cannot return to my original universe as we didn't have the means to capture signatures in my timeline yet when I left. I came here knowing that. No I will not tell you about your future, because your future is not my future, so I don't know it yet.

  • The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes

    Nice first step, but I'll be more impressed when the results are in agreement with predictions from the 1890s

    • The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes

      Nice first step, but I'll be more impressed when the results are in agreement with predictions from the 1890s

      Predictions from the 2090s have completely refuted this time travel nonsense, however.

  • Various physicists (Score:5, Interesting)

    by Darth Snowshoe ( 1434515 ) on Thursday January 29, 2015 @11:34AM (#48931583)

    "Various physicists have discovered solutions to Einstein’s field equations that contain loops that return to the same point in space and time."

    What a lazy bit of reporting! Mr. Kurt Friedrich Gödel first discovered the Einstein's general relativity allowed for closed timelike curves. He presented a paper describing this solution to Einstein as a birthday present, while they were both working at the IAS. It grieves me when Gödel is not given the recognition he is certainly due.

    • by Anonymous Coward

      "Various physicists have discovered solutions to Einstein’s field equations that contain loops that return to the same point in space and time."

      What a lazy bit of reporting! Mr. Kurt Friedrich Gödel first discovered the Einstein's general relativity allowed for closed timelike curves. He presented a paper describing this solution to Einstein as a birthday present, while they were both working at the IAS. It grieves me when Gödel is not given the recognition he is certainly due.

      I read your title and recalled the Douglas Adams line:

      "Many respectable physicists said that they were going to stand for that sort of thing, partly because it was a debasement of science, but mostly because they didn't get invited to those sorts of parties."

      I agree that Godel doesn't get enough credit. I am not sure why he is not taken seriously, because other than the idea of creating a time machine sounding a little crazy to some, the scientist Dr Ronald Mallett has been researching a way to create a mol

    • by Unixnoteunuchs ( 990069 ) on Thursday January 29, 2015 @02:53PM (#48933335)
      Accounts of Dr. Gödel's contributions are often inconsistent or incomplete.
    • by Anonymous Coward

      What a lazy bit of reporting!

      Welcome to /.

  • Speak for yourself.

  • You mean a big ball of wibbly-wobbly... timey-wimey... stuff [imdb.com]? Even the light sci-fi tends to be a couple steps ahead of physics.

  • Let me know when someone builds a Predictor [nature.com].

    • What, you don't have those in the States yet?

      http://www.predictor.eu/ [predictor.eu]

    • You can sort of simulate one. Build a device that flashes a light when you press the button - but slowly increase the delay from 0 to... well, I'm not sure exactly, 0.25s? Something like that.

      Anyway, if you do this right, your brain will "edit out" the delay (something it does all the time to reconcile differences between the senses).

      Then at some point, the device resets the delay to 0. Next time you press the button, your brain will convince you that the light came on before you pressed.

  • by NEDHead ( 1651195 ) on Thursday January 29, 2015 @12:00PM (#48931783)

    but kept up back at the beginning

  • If I go back in time and kill the old version of myself - is that suicide or murder?

  • Well... (Score:2, Interesting)

    by kdub007 ( 3899329 )
    I don't fully understand what they did. But, here's my take. It would seem to me that they may have demonstrated that there is not a single timeline, which kinda goes along with some other assumptions in Quantum mechanics. Relativity assumes that Time is a constant so-to-speak. Quantum Mechanics does not. How this experiment might lead to unifying Relativity with Quantum I don't know, and don't believe, because I think both theories (and they are both THEORIES) are flawed.
  • This immediately made me think, well what if time travel isn't possible, but a simulation of it, of the past, is, using this.

    And of course that immediately made me think of the possible scifi stories that could explore this concept or use this as a literary device.

    And then I realized this has sort of been done already, in the episode of ST:NG, The Inner Light (a personal favorite).

    • Stephen Baxter's (and Arthur C. Clarke, but he barely wrote a word of it) "The Light of Other Days" explores something along those lines. It's a good read.
  • ... go back in time and produce TFA in a smaller font. Seriously, the NSA could probably read that from space.

  • Ah, but this machine only goes forward in time, so you won't be able to change history or do something disgusting like sleep with your own grandmother. -Farnsworth
  • The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes.

    That is the beauty of time travel experiments. You just go back in time and adjust the predictions. Simple, eh?

  • Bah. The BBC has been simulating a time machine for decades.

  • So if you considered both string theory(?) of multiple universes formed from choices (all simultaneous outcomes exist until one choice is made then the rest collapse) and the paradox problem, it seems that a paradox is not actually a problem, as the logical outcome of that choice ( to kill your grandfather) would collapse itself leaving all the other choices/universes.

    So basically, paradoxes cannot exist. what can exist does.

  • There are no paradoxes; somebody invents time travel, and somebody goes back and changes things, and changes ripple forwards, and somebody else (or the same) goes back and changes things, and changes ripple forwards, and so on and so on, until somebody changes things into a future where time travel is never invented, and that is a stable trap, and everything marches forwards from there.

"Well I don't see why I have to make one man miserable when I can make so many men happy." -- Ellyn Mustard, about marriage

Working...