Submitted via IRC for SoyCow1984
Physicists reverse time using quantum computer
Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past. They also calculated the probability that an electron in empty interstellar space will spontaneously travel back into its recent past. The study is published in Scientific Reports.
"This is one in a series of papers on the possibility of violating the second law of thermodynamics. That law is closely related to the notion of the arrow of time that posits the one-way direction of time from the past to the future," said the study's lead author Gordey Lesovik, who heads the Laboratory of the Physics of Quantum Information Technology at MIPT.
"We began by describing a so-called local perpetual motion machine of the second kind. Then, in December, we published a paper that discusses the violation of the second law via a device called a Maxwell's demon," Lesovik said. "The most recent paper approaches the same problem from a third angle: We have artificially created a state that evolves in a direction opposite to that of the thermodynamic arrow of time."
(Score: 1, Informative) by Anonymous Coward on Monday March 18 2019, @08:51AM (3 children)
if I run a movie backwards, I do not claim to have reversed time. maybe that's why I don't have a tenured position yet.
(Score: 5, Informative) by davidjohnpaul on Monday March 18 2019, @08:56AM
https://www.technologyreview.com/s/613123/no-ibm-didnt-just-reverse-time-with-a-quantum-computer/ [technologyreview.com]
(Score: 0) by Anonymous Coward on Monday March 18 2019, @09:16AM (1 child)
If you claimed that it could, and therefore could result in <insert boogie man or catastrophe of your choice>, you could become a politician.
(Score: 0) by Anonymous Coward on Monday March 18 2019, @11:12AM
Of course everyone knows that going back in time may cause causality paradoxes which destroy the universe. Or at least the Earth.
(Score: 2) by Thexalon on Monday March 18 2019, @12:37PM (10 children)
If it had been possible:
1. Hitler would have been assassinated when he was a complete nobody.
2. Somebody would have gotten very rich from correctly predicting lotto numbers and sports results.
3. John Titor might have gotten something right.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 0) by Anonymous Coward on Monday March 18 2019, @12:55PM (1 child)
4. There would be numerous stories of encounters with secretive advanced civilizations who want to investigate the human body, that are (for some reason) always lacking in physical proof, since the time-traveling future humans can travel through time and get their stuff back.
(Score: 0) by Anonymous Coward on Monday March 18 2019, @05:06PM
5) I would have gotten first post.
(Score: 4, Touché) by takyon on Monday March 18 2019, @01:04PM (3 children)
Not if time traveling makes you exit your current universe and pop into existence in another one, leaving the original universe unaffected except for your sudden absence.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by acid andy on Monday March 18 2019, @05:03PM (2 children)
I've always liked this idea because it seems to avoid paradoxes. If time travel becomes possible though, I imagine lots of people will do it lots of times which would create lots of universes with time travelers in compared to just our current one that hasn't got any. If it reaches the order of thousands more with time travelers then it becomes unlikely that we were lucky (unlucky?) enough to wake up in the universe without any time travelers--unless in the universe the time traveler arrives in, none of the other beings are conscious.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by arslan on Monday March 18 2019, @11:01PM
How do we know our current does have any? Maybe we do. Also, there's no guarantee that those said time travellers know they are time travellers. A side effect of the time shift could be that it mucks with their consciousness in a way we don't even know.
Maybe Buddha and Jesus are time travellers, but the said process have stripped them of most of their futuristic advantages and only left them with some innate conscious edge that projects a perception of slightly superiority - and the experience left them with no recollection that they're from the future. It could be that time travel only works to project one's consciously into another host in the past and not their physical bodies.
There's so much we don't know, just possibilities from our pop-culture which may be void of bunch of limitations/restrictions to serve a fictional plot.
(Score: 0) by Anonymous Coward on Tuesday March 19 2019, @11:26PM
the paradox of killing own grandpa can be solved without multiverse assuming failure. It's like observing a vase, unbroken at t=0s and at t=8s and postulating that it 'will' be unbroken at t=3s.
(Score: 0) by Anonymous Coward on Monday March 18 2019, @04:03PM (1 child)
Not possible because it would cause a paradox: If you managed to kill Hitler when he was a complete nobody, then there would not be a future incentive to kill Hitler (you'd not even know about his existence!), therefore you would not go back to kill Hitler in the first place.
Maybe by the time when time machines are invented, any riches you could earn in our day by playing the lottery or betting on sports would have been rendered worthless.
Time travel being possible doesn't imply that John Titor was a time traveller. After all, medicine is real, yet not everyone who claims to be able to heal you actually is able to.
And of course there is the possibility that time travel is possible, but not arbitrary time travel. That is, time travellers of the future might not be able to go back into our time due to limitations of the time travel mechanism.
(Score: 2) by acid andy on Monday March 18 2019, @05:16PM
You would if your future time-traveling self was a blabbermouth that publicized evidence about who he would become. Anyway, from the perspective of you as the time-traveler, the events that motivated your trip through time have already happened in your own past. From your perspective, the new future you that doesn't know of the war is a distinct individual. Maybe!
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 1) by khallow on Monday March 18 2019, @06:07PM (1 child)
Maybe he's been assassinated numerous times and you just heard about the one they decided to leave because it was better than the alternatives?
Much more likely for us to see. And well, we do see something [milwaukeeindependent.com]. Of course, it's far more likely to be exploitation of shoddy lottery design, but time travelers would know how to do that too in order to blend in.
(Score: 2) by GreatAuntAnesthesia on Tuesday March 19 2019, @10:38PM
Maybe he's been assassinated numerous times and you just heard about the one they decided to leave because it was better than the alternatives?
Indeed: https://www.tor.com/2011/08/31/wikihistory/ [tor.com]
(Score: 2) by acid andy on Monday March 18 2019, @12:54PM (2 children)
Time could be running backwards right now but we wouldn't be able to tell because our memories would still only be of past events.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 2) by c0lo on Monday March 18 2019, @01:34PM (1 child)
FTFY
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by acid andy on Monday March 18 2019, @04:22PM
If you mean future events in the sense of their actually happening after past events then I'd agree with you. If you mean future events in the sense of the higher entropy events that take place in what we currently call the future with time running forwards, then I disagree. I'm imagining time running backwards in this universe being like playing a movie in reverse--all the events and characters thoughts and decisions are the same but they just play out in reverse order.
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 1) by Rupert Pupnick on Monday March 18 2019, @09:26PM
This is a real credibility boost to the field of quantum computing ! Look at all that math! I mean, sure, it’s a bit light on details surrounding the experimental result, but who knows! Could be the biggest thing since cold fusion!
(Score: 2) by hendrikboom on Tuesday March 19 2019, @01:17AM (3 children)
The direction of time is an emergent statistical phenomenon.
Feynman diagrams are time-invariant. You can run them forwards, backwards, left-to-right, down-to-up, and they are all just as valid.
It's no surprise that a quantum event in a quantum computer doesn't care about the direction of time.
But there's not enough statistical behaviour to trigger entropy as a direction in time.
Rivelli's book on quantum gravity says, if you fine there's a direction in space-time where entropy increases, you can choose to call it time. But you need enough effective randomness for entropy to be meaningful.
(Score: 2) by acid andy on Tuesday March 19 2019, @02:46AM
Is this anything more than a linguistic issue though? In the sense that it just doesn't deserve to be called time because that word ceases to be a useful label due to it lacking the properties we normally ascribe to time? If so that doesn't necessarily mean it really ceases to be time in a physical sense. It strikes me as sounding a bit like the question as to whether a tree falls in a forest if no-one is there to hear it. I don't know.
DISCLAIMER: I am AINQP and AINQP Is No Quantum Physicist!
If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
(Score: 0) by Anonymous Coward on Tuesday March 19 2019, @06:33AM (1 child)
what do you find so confusing about this?
time has a given direction. for some reason in most basic phenomena the equations are invariant to time reversals.
but the universe is not a basic phenomenon. the moment you introduce complexity, you lose statistical time invariance.
the probability of observing a closed system with decreasing entropy is practically zero for macroscopic systems.
but Poincare's theorem says this will happen, and it has been observed for small enough systems.
time does not emerge from complexity, it's direction is just made evident by our imperfect measurements. and once you introduce quantum effects, there are inherent stochastic effects that serve to spread out probability distributions, again making time's direction evident.
(Score: 0) by Anonymous Coward on Tuesday March 19 2019, @10:46PM
Yeah man, what's so difficult about that? Geez!