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https://www.livescience.com/63182-quantum-computer-reverse-arrow-time.html
A new technique for quantum computing could bust open our whole model of how time moves in the universe.
A new paper, published July 18 in the journal Physical Review X [ https://journals.aps.org/prx/abstract/10.1103/PhysRevX.8.031013 ], opens the door to the possibility that the arrow pf time is an artifact of classical-style computation — something that's only appeared to us to be the case because of our limited tools.
A team of researchers found that in certain circumstances causal asymmetry disappears inside quantum computers.
In this paper, the researchers looked at physical systems that had a goldilocks' level of disorder and randomness — not too little, and not too much.
They tried to figure out those systems' pasts and futures using theoretical quantum computers (no physical computers involved). Not only did these models of quantum computers use less memory than the classical computer models, she said, they were able to run in either direction through time without using up extra memory. In other words, the quantum models had no causal asymmetry
"While classically, it might be impossible for the process to go in one of the directions [through time]," said Jayne Thompson, of the National University of Singapore, "our results show that 'quantum mechanically,' the process can go in either direction using very little memory."
And if that's true inside a quantum computer, that's true in the universe, she said.
Quantum physics is the study of the strange probabilistic behaviors of very small particles — all the very small particles in the universe. And if quantum physics is true for all the pieces that make up the universe, it's true for the universe itself, even if some of its weirder effects aren't always obvious to us. So if a quantum computer can operate without causal asymmetry, then so can the universe.
Thompson added that the research doesn't prove that there isn't any causal asymmetry anywhere in the universe. She and her colleagues showed there is no asymmetry in a handful of systems. But it's possible, she said, that there are some very bare-bones quantum models where some causal asymmetry emerges.
(Score: 2) by Bot on Wednesday August 08 2018, @12:02PM
> This means activity is EITHER happening faster than the planck time, in which case it's completely non-deterministic in much the same way as a race condition in your own source code might be, or...
> Time is able to be rewritten at some scales.
I maybe misunderstand you, but I think you are making up a meta arrow of time. You are in good company.
The classical model is: the state of the universe, on which the laws of physics work with planck scale resolution, and an arrow of time IN WHICH laws of physics operate.
Quantum scale anomalies in experiments proved this wrong, but people do not really acknowledge time as just another product of the computation. Time is change, is itself a product. The correct model is, whatever is meta defines spacetime according to seemingly consistent rules. If you do without a time in which the universe "is computed", then it is possible for the meta to calculate according to future states, to "rewrite time", to do whatever. Being outside time means BEING UNAFFECTED BY TIME. How is it possible to do that? well we would need to go outside time and see how it's done. But that is as unlikely as your game of conway structures to wake up one day and think the universe as NOT made by a matrix of 1 and 0.
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