Why we probably don’t live in a computer simulation

Over at her blog, BackReAction, physicist Sabine Hossenfelder has written a cogently argued article titled, No, we probably don’t live in a computer simulation (March 15, 2017). I’ll quote the most relevant excerpts:

According to Nick Bostrom of the Future of Humanity Institute, it is likely that we live in a computer simulation

Among physicists, the simulation hypothesis is not popular and that’s for a good reason – we know that it is difficult to find consistent explanations for our observations…

If you try to build the universe from classical bits, you won’t get quantum effects, so forget about this – it doesn’t work. This might be somebody’s universe, maybe, but not ours. You either have to overthrow quantum mechanics (good luck), or you have to use qubits. [Note added for clarity: You might be able to get quantum mechanics from a classical, nonlocal approach, but nobody knows how to get quantum field theory from that.]

Even from qubits, however, nobody’s been able to recover the presently accepted fundamental theories – general relativity and the standard model of particle physics…

Indeed, there are good reasons to believe it’s not possible. The idea that our universe is discretized clashes with observations because it runs into conflict with special relativity. The effects of violating the symmetries of special relativity aren’t necessarily small and have been looked for – and nothing’s been found.

I have in the past criticized the theory of the multiverse on several grounds (see here and here), one of them being that the existence of the multiverse appears to imply the existence of a great multitude of intelligently designed universes, as well as making it overwhelmingly likely that we are living in a “fake universe” or simulation. After reading Dr. Hossenfelder’s article, I feel compelled to withdraw this argument.

Another alleged problem with the multiverse hypothesis is that if we live in a multiverse, then we would expect biological life-forms like ourselves to be vastly outnumbered by “Boltzmann brains.” But this argument presupposes that the evolution of a Boltzmann brain is statistically more likely than that of a carbon-based life-form like ourselves. I now believe this is not the case. The formation of a self-aware brain as a result of a random fluctuation in the entropy of the cosmos is a fantastically unlikely event, akin to Fred Hoyle’s Boeing 747 forming from a tornado in a junkyard. The reason why it is so unlikely is that it has to take place over a very, very short time period, since a brain-in-the-making that formed gradually would be destroyed by the forces of nature long before it became self-aware. A stand-alone, self-aware brain might seem easier to generate than a complex organism possessing a brain, but one has to consider the pathway as well. An evolutionary pathway permits trial-and-error testing and cumulative improvements; a sudden random fluctuation that gives rise to a brain does not.

There are, however, other problems with the multiverse hypothesis as an explanation of fine-tuning: a multiverse capable of generating even one life-supporting universe would still need to be fine-tuned (as Dr. Robin Collins has pointed out); the multiverse hypothesis predicts that a universe containing intelligent life should be much smaller than the one we live in; and the multiverse hypothesis cannot account for the fact that the laws of physics are not only life-permitting, but also mathematically elegant – a fact acknowledged even by physicists with no religious beliefs.

That doesn’t mean there is no multiverse, of course. But what it does mean is that it can’t be invoked to explain away fine-tuning.

What do readers think?

11 thoughts on “Why we probably don’t live in a computer simulation”

  1. Neil Rickert

    That doesn’t mean there is no multiverse, of course. But what it does mean is that it can’t be invoked to explain away fine-tuning.

    Fine tuning is an illusion. So it does not need to be explained away.

    The weak anthropic principle is already a sufficient basis for concluding that fine tuning is an illusion.

  2. GlenDavidson

    What do readers think?

    I think it’s strange that from an article arguing that we’re likely not living in a simulation the discussion moves without reason to being about the multiverse.

    I also think that IDists seem to care a good deal more about the supposed multiverse than almost everyone else does.* It’s possible, presumably, but without evidence I don’t happen to care much either way.

    Glen Davidson

    *Presumably because making up a Cause is sufficient for them.

  3. Robert Byers

    i’m not interested in multi anything but folks saying we live in a computer simulation ish reality is just plain dumb.
    We live in a created thing, by God, and we don’t see/touch the real kingdom. Heaven. Yet we are real enough. We were meant to exist forever in this universe but it failed.
    We will get a new heaven and earth.
    Who pays these people and when are they gonna stop?!

  4. waltowalto

    GlenDavidson: I think it’s strange that from an article arguing that we’re likely not living in a simulation the discussion moves without reason to being about the multiverse.

    I also think that IDists seem to care a good deal more about the supposed multiverse than almost everyone else does.*It’s possible, presumably, but without evidence I don’t happen to care much either way.

    Glen Davidson

    *Presumably because making up a Cause is sufficient for them.

    That was my sense of this OP: it basically changes the subject. The piece being discussed was not primarily about the multiverse hypothesis.

  5. vjtorley Post author

    walto and Glen Davidson,

    The unified theme linking the idea that we’re living in a computer simulation to the question of whether the multiverse requires fine-tuning is: Intelligent Design (whether by aliens or a transcendent Deity). Need I say more?

  6. GlenDavidson

    vjtorley:
    walto and Glen Davidson,

    The unified theme linking the idea that we’re living in a computer simulation to the question of whether the multiverse requires fine-tuning is: IntelligentDesign (whether by aliens or a transcendent Deity). Need I say more?

    Oh, so it’s about your unwarranted jump to conclusions.

    That may be, but what’s that to us? You may think “if it’s not explained, then God explains it,” yet that “conclusion” doesn’t follow and it doesn’t make sense. Fine-tuning is an issue, and it would be nice if it were explained, only if it isn’t explained it’s still just a question and not something that points to a God or any such thing.

    Really, is there anything to ID except the fallacy (false dilemma) that, if something isn’t explained, then “God” is the answer? I know that sermons have primed endless numbers of people to believe that, it still is neither valid nor sound.

    Glen Davidson

  7. Kantian NaturalistKantian Naturalist

    Bostrom does not think it’s “likely” that we’re living in a simulation. What he says — clearly — is

    at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation.

    Put otherwise, Bostrom’s point is that one of the following three claims is false:

    1. human beings will never evolve into a post-human civilization;
    2. post-human civilizations will never be interested in constructing simulations of their historical ancestors;
    3. we are not actually living in such a simulation.

    Bostrom then has to introduce quite a few assumptions (which to me look highly questionable) to get all three of these options on the table. But once on the table, he concludes that there’s no way of assigning probabilities to them. Hence the claim that according to Bostrom it’s likely that we’re living in a computer simulation is simply false.

  8. colewd

    vjtorley,

    Indeed, there are good reasons to believe it’s not possible. The idea that our universe is discretized clashes with observations because it runs into conflict with special relativity.

    I don’t understand this argument. If the universe is a simulation a possible scenario it the discrete unit is the atom. As a simulation atoms would be addressable units under central control. Why would special relativity be in conflict?

  9. waltowalto

    vjtorley:
    walto and Glen Davidson,

    The unified theme linking the idea that we’re living in a computer simulation to the question of whether the multiverse requires fine-tuning is: IntelligentDesign (whether by aliens or a transcendent Deity). Need I say more?

    Yes, you’ll need to say more for me to understand that alleged connection.

  10. Neil Rickert

    walto: Yes, you’ll need to say more for me to understand that alleged connection.

    There is no connection between “fine tuning” and the multiverse.

    However, there most certainly is an alleged connection.

    For a long time, the ID proponents have been claiming that multiverse theories are an atheist conspiracy to defeat “fine tuning” arguments, by vastly increasing the probability that apparent fine tuning might randomly pop up somewhere in the multiverse.

  11. waltowalto

    Neil Rickert: There is no connection between “fine tuning” and the multiverse.

    However, there most certainly is an alleged connection.

    For a long time, the ID proponents have been claiming that multiverse theories are an atheist conspiracy to defeat “fine tuning” arguments, by vastly increasing the probability that apparent fine tuning might randomly pop up somewhere in the multiverse.

    Aha–thanks! I get it: with a multiverse, the probability is…..1–God or no God.

    So then what? Are we supposed to count the number of individual universes with and those without and find the ratio of those sums? That’d take awhile, I think–even with a nice notebook and a bunch of pens.

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