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posted by martyb on Thursday July 30 2020, @07:42AM   Printer-friendly
from the ♫-we're-going-back-in-time-♫ dept.

Simulating quantum 'time travel' disproves butterfly effect in quantum realm:

Using a quantum computer to simulate time travel, researchers have demonstrated that, in the quantum realm, there is no "butterfly effect." In the research, information—qubits, or quantum bits—'time travel' into the simulated past. One of them is then strongly damaged, like stepping on a butterfly, metaphorically speaking. Surprisingly, when all qubits return to the 'present,' they appear largely unaltered, as if reality is self-healing.

[...] In the team's experiment, Alice, a favorite stand-in agent used for quantum thought experiments, prepares one of her qubits in the present time and runs it backwards through the quantum computer. In the deep past, an intruder—Bob, another favorite stand-in—meaures[sic] Alice's qubit. This action disturbs the qubit and destroys all its quantum correlations with the rest of the world. Next, the system is run forward to the present time.

According to Ray Bradbury, Bob's small damage to the state and all those correlations in the past should be quickly magnified during the complex forward-in-time evolution. Hence, Alice should be unable to recover her information at the end.

But that's not what happened. Yan and Sinitsyn found that most of the presently local information was hidden in the deep past in the form of essentially quantum correlations that could not be damaged by minor tampering. They showed that the information returns to Alice's qubit without much damage despite Bob's interference. Counterintuitively, for deeper travels to the past and for bigger "worlds," Alice's final information returns to her even less damaged.

"We found that the notion of chaos in classical physics and in quantum mechanics must be understood differently," Sinitsyn said.

The more damage you do in the past, the less the present is affected?


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  • (Score: 0) by Anonymous Coward on Friday July 31 2020, @07:02AM (1 child)

    by Anonymous Coward on Friday July 31 2020, @07:02AM (#1029171)

    It's an idiomatic phrase. The individual words in the phrase don't matter, just the use of the phrase as a whole, and "begs the question" to mean "raises the question" is far more common to the point where people bringing up the issue of something assuming the conclusion is true will just outright say the words "assumes the conclusion".
    In fact, the fucking name in that latter sense is still idiomatic, because it's a terrible, terrible translation of the Latin phrase (which was also altered a bit from the Greek it derived from).

  • (Score: 2) by aristarchus on Friday July 31 2020, @10:16AM

    by aristarchus (2645) on Friday July 31 2020, @10:16AM (#1029185) Journal

    You are begging the question. Or looking for a beating. It is a technical usage, and the common usage is based on an illiterate similarity. The Greek is nothing like the Latin, it is τὸ ἐξ ἀρχῆς. So your entire objection is something of a damp squid. It is rough to be stupid and wrong like this, but at least it is better than being stupid and right, because it gives you plausible deniability.