The GZK Test of Whether We Are In a Simulation

The world of Digital Physics is generally immune from appearing in mainstream media. But some nights ago, during an insomnia induced late night TV viewing, on a mainstream news source (either BBC or Al Jazeera English, can’t remember which) I saw a piece on Are We In a Computer Simulation? And the term Digital Physics was bandied about.

A google search showed activity in various mainstream news websites that appeared to feed off an article at the MIT Technology Review website that you can find here, which talks about an arXiv technical article that you can find here.

Interlaced tracks at Amsterdam Centraal

Interlaced tracks at Amsterdam Centraal (Photo credit: Daniel Sparing)

It talks about the universe being a regular cubic lattice of points, with an observable effect occurring when light travels parallel to the lines of the lattice, sort of like getting your car tyres stuck in tram tracks.

So what can we make of this?

Well, the first thing that jumps out at me is the confounding of two separate ideas:

1. That the universe is a digital array of points

2. That this array is simulated on a computer … that somebody created!!!!

I thought maybe that it was only the more mainstream sources talking up the latter idea, but within the arXiv article the authors (Silas R. Beane, Zohreh Davoudi, Martin J. Savage) say

Extrapolations to the distant futurity of trends in the growth of high-performance computing (HPC) have led philosophers to question – in a logical compelling way – whether the universe we currently inhabit is a numerical simulation performed by our distant descendants [1].

with the footnote to [1] linking to an article by Nick Bostrom, a well-known philosopher with an interest in the are-we-computer-simulations idea. He believes that at least one of the following are true (I’ve simplified them and hopefully not changed their intent):

* No civilization can simulate to the complexity of our universe

* No civilization will choose to simulate to the complexity of our universe very often

* We are almost certainly computer simulations

I’ve already stated my position on this: all of the above can be false because we can be a mathematical construct that exists because mathematics exists in its own right, and I don’t believe there’s any reason to suppose we’re in a constructed simulation. There seems to be this strange presumption that a digital universe must be a created simulation while a continuous universe does not. I’ve never really understood this logic.

So we see that the Beane et al paper was originally motivated by the idea of an intelligently designed simulation. Oops, did I say that? Anyway, the motivation, to me, is unimportant if the result is real science, which this paper clearly is.

The second thing I’d comment on is that the digital model being tested is a uniform cubic lattice. In Beane et al they talk of the a very fine level lattice down to several fermis (10^-15 metres). I view these digital models as being approximations to continuous models, where the continuous models are approximations to the actual digital structure of our universe. In this way they’ve come full circle back to a digital model of a digital structure. But it’s not necessarily the same digital model. In fact I think it’s highly unlikely that the universe is a uniform grid, for various reasons I think it’s far more likely that it’s a locally irregular grid (although I don’t entirely rule out a uniform grid). Alex Lamb also likes the irregular grid approach. coincidentally wrote a similar piece to this post on the same day here. An irregular grid should still yield observable effects: instead of getting caught in tram tracks, light would get knocked about like riding over cobblestones.

So, personally I’d be gobsmacked if their test uncovers anything, but it’d be great if it did. I hope they continue with it and I hope they succeed.

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