Scientists simulate backward time travel using quantum entanglement
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Re: Scientists simulate backward time travel using quantum entanglement
#2Paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13...
> We construct a metrology experiment in which the metrologist can sometimes amend the input state by simulating a closed timelike curve, a worldline that travels backward in time. The existence of closed timelike curves is hypothetical. Nevertheless, they can be simulated probabilistically by quantum-teleportation circuits. We leverage such simulations to pinpoint a counterintuitive nonclassical advantage achievable with entanglement. Our experiment echoes a common information-processing task: A metrologist must prepare probes to input into an unknown quantum interaction. The goal is to infer as much information per probe as possible. If the input is optimal, the information gained per probe can exceed any value achievable classically. The problem is that, only after the interaction does the metrologist learn which input would have been optimal. The metrologist can attempt to change the input by effectively teleporting the optimal input back in time, via entanglement manipulation. The effective time travel sometimes fails but ensures that, summed over trials, the metrologist’s winnings are positive. Our Gedankenexperiment demonstrates that entanglement can generate operational advantages forbidden in classical chronology-respecting theories.
Re: Scientists simulate backward time travel using quantum entanglement
#3Layperson's read but the paper seems to say "this is weird we were accurate than should be possible" combined with "causal order wouldn't make sense here"
Much less "we found time travel" and more "that was weird maybe it was time travel".
Also note that to my knowledge there is no form of talking about entanglement that involves time before entanglement or any meaningful manipulation of the entangled particle.
Thus even if you could talk backwards in time with entangled particle it is unlikely to make a meaningful difference at distances measured less than how far light travels in that time.
Re: Scientists simulate backward time travel using quantum entanglement
#4I simulate backward time travel all the time
It's called my imagination...
Re: Scientists simulate backward time travel using quantum entanglement
#5I simulate backward time travel all the time It's called my imagination...
Yah but have you set up a set of statically significant entangled bosons in a Hau array and then coupled those to your cerebral cortex to be able to meaningfully act upon the knowledge gained by said imagination?…
Re: Scientists simulate backward time travel using quantum entanglement
#6I simulate backward time travel all the time It's called my imagination...
Yah but have you set up a set of statically significant entangled bosons in a Hau array and then coupled those to your cerebral cortex to be able to meaningfully act upon the knowledge gained by said imagination?…
I mean, not lately
Re: Scientists simulate backward time travel using quantum entanglement
#7Wow these ads are intrusive. I just got done listening to Penrose talking about this. Interesting timing.
Re: Scientists simulate backward time travel using quantum entanglement
#8Paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13... > We construct a metrology experiment in which the metrologist can sometimes amend the input state by simulating a closed timelike curve, a worldline that travels backward in time. The existence of closed timelike curves is hypothetical. Nevertheless, they can be simulated probabilistically by quantum-teleportation circuits. We leverage such simul…
There is a nice explanation at the end of the letter: “While PCTC simulations do not allow you to go back and alter your past, they do allow you to create a better tomorrow by fixing yesterday’s problems today.”
Re: Scientists simulate backward time travel using quantum entanglement
#9I suppose the actual paper is describing retrocausality and not time travel but maybe I'm perceiving that wrong?
Re: Scientists simulate backward time travel using quantum entanglement
#10The letter discusses a theoretical framework to understand certain quantum phenomena, which includes simulating hypothetical constructs known as Closed Timelike Curves (CTCs). CTCs in the realm of general relativity are paths through spacetime that, if they could exist, would allow for time loops and, in that sense, "time travel." However, in this letter, CTCs are not being used to propose actual time travel, but are rather a conceptual tool to explore certain quantum behaviors.
In the scenario outlined in the paper, the authors simulate CTCs using quantum-teleportation circuits to explore how information can be "sent" back in time, effectively. In other words, they explore a situation where information from the future could be used to amend the state of a quantum system in the past to achieve a metrological advantage. They employ quantum entanglement and post-selection to simulate a scenario where a certain state in a quantum metrology experiment can be determined based on future information, which is then effectively sent back to amend the initial state of the system.
The key takeaway is that the authors are not suggesting actual time travel, but are employing the notion of CTCs and quantum simulation to delve into a complex theoretical exploration of quantum metrology. This exploration reveals how entanglement can simulate what would be effects of retrocausality, meaning effects that appear to violate the typical forward flow of cause and effect, to achieve certain advantages in metrology, which is the science of measurement. From GPT In essence, this is a very high-level theoretical discussion that uses the concept of time travel as a tool to explore certain quantum phenomena, rather than a proposal or explanation of practical time travel.