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MIPT just reversed time... for a certain definition of time


DAL59

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  On 3/14/2019 at 4:26 AM, DAL59 said:

Scientists were able to revert an electron to a lower entropy quantum state that it was in .1 nanoseconds ago.

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Only the state, not time. Time symmetry is known to be broken (at least on it's own).

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Article (open access):

https://www.nature.com/articles/s41598-019-40765-6

A little over my head :-) It may be that "time reversal" is just a misunderstanding or media exaggeration, derived from the title, as this seems to be just an algorithmic simulation ? Waiting for the cracks to show up ...

Edited by Green Baron
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I'm not suggesting that their research is wrong - I have zero competence on the subject, hasn't followed the subject for the last 3 years, and has practically forgot the majority of 'modern' physics; though if you come ask me something about statics analysis, I'll give you some answer - but the way how they're testing this "reversals" seems to suggest more on a "reset of a computer state" - which if you've seen classical, non-quantum computers, you know it's fully possible - rather than reversing the arrow of time; and if anything I'm sure that this discovery is much more of a benefit on quantum computing than on going back through time.

On the subject of "is it possible to reverse time", the answer seems... no, as that'd involve things that looks different when you do it. Entropy isn't the only ones, however...

Paper on the breaking of time symmetry, on itself https://arxiv.org/pdf/1410.1742.pdf

But again, I'll stress that I'm just an incompetent fool on the internet, in the subject of quantum physics.

Edited by YNM
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This is a reversal of time, in a sense. It's like throwing a vase onto the ground, and then reversing your arm movement, and having the vase put itself back together in your hands. Not really time reversal, but it's actually easier to understand it if you think that time has actually reversed. 

So, the implications of this discovery in the context of reversable computing: Discuss! 

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Apart from the colourful news pages, this guy has drastic words on it:

https://www.technologyreview.com/s/613123/no-ibm-didnt-just-reverse-time-with-a-quantum-computer/

tl,dr

Analogy would be to let a tape rewind (on a quantum scale) while time travels on into the future, or a lens that can be used to focus or disperse light. In both cases it appears to the observer that something went backward in comparison to before, but that was not the case. It was just two versions of a physical process under the watchful eye of thermodynamics.

He concludes citing a colleague: “This is the type of hype that is going to give quantum computing a bad name.”

What now ? I can do a little C/C++ tinkering on a hobby level. I doubt this qualifies me for an own opinion
:cool:

 

Edited by Green Baron
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