Are we living in a simulation? A flurry of headlines says no: we need no longer worry about our lives being mere software spawned by a highly advanced supercomputer.

These stories stem from a recent Science Advances paper about simulating quantum physics. One science magazine extrapolated from this to suggest that storing information about just a few hundred electrons needs a computer memory made up of more atoms than exist in the universe – thus, simulating the universe is impossible.

But the paper only claims that a specific, limited type of simulation won’t work due to technical and hardware issues. It says that, within our current understanding of physical reality, there are certain quantum problems that cannot be simulated on a classical computer using a specific quantum algorithm, because it would require too much memory. The paper doesn’t even mention electrons.

While pleased at the coverage of their work, authors Zohar Ringel at the Hebrew University of Jerusalem, Israel, and Dmitry Kovrizhin at the University of Oxford told New Scientist they are a bit taken aback at the conclusions the media is drawing. Asking whether we live in a simulation is not even a scientific question, Ringel says.

The simulation hypothesis has been gaining prominence since 2002, when Nick Bostrom, a philosopher also at the University of Oxford, claimed that a computer with the mass of a planet and capable of 1042 calculations per second could simulate the entire mental history of humankind by using less than one-millionth of its processing power for 1 second.

Bostrom’s ideas have prompted technology moguls like Elon Musk to believe that there is only a billion-to-one chance that we actually live in reality. It is far more likely, they say, that we are merely data circling inside someone’s supercomputer. The idea of a simulated reality, of course, brings up questions of free will and whether or not humanity controls its own destiny.

But should we even care about a question that we don’t have enough information to answer? “To me, both the ‘are we living in a simulation’ question and any response to it based on current computer knowledge is silly,” says Marcelo Gleiser at Dartmouth College in Hanover, New Hampshire. “Bostrom’s paper assumes that there is an interest from a hyper-advanced civilisation in simulating the past, that is, retroactively. Usually it’s the other way around – we look forward with computers.” In all likelihood, our post-human descendants wouldn’t care enough to simulate a reality for us anyway.

Gleiser brings up a second, perhaps more salient point: trying to answer these questions based on our current knowledge and machines is risky. Quantum computers – if and when they become truly operational – may be much more versatile than we can imagine at this point. If we were in a simulation, humans would have little idea of what the laws of physics in the outside “real world” were like, whether quantum mechanics ruled, and what kind of computation was possible outside the bounds of our simulation.

“In my opinion the question is much more fiction than science,” Gleiser says. When operating on the fringes of science, Bostrom, Musk and the like can make any argument in support of their views.

Original Source: https://www.newscientist.com/article/2149627-we-cant-ever-know-whether-or-not-our-universe-is-a-simulation/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=physics&campaign_id=RSS%7CNSNS-physics

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