C'mon, you wanna live forever?

This morning I was casting about for topics for Skeptophilia and happened upon one that kind of made my brain explode.  Part of this was I came across it prior to my first cup of coffee, but even now that I'm reasonably well caffeinated it still leaves me in a superposition of "Okay, I get it" and "... wait, what?"

I use the "superposition" metaphor deliberately because this, like yesterday's post about Quantum Weeping Angels, is about the weirdness of quantum physics.  To frame this, let's start with a refresher on two concepts that will be familiar to most of you -- Schrödinger's Cat and the Many-Worlds Interpretation.

Schrödinger's Cat -- a thought experiment dreamed up by the brilliant physicist Erwin Schrödinger -- looked at the bizarre prediction that with a quantum process, the phenomenon exists in the form of a wave function describing the probabilities of various outcomes.  Until observed or measured, the wave function is the reality; it's not that the outcome is already decided, and we simply don't know at the moment which option is true (as in a classical situation like flipping a coin, prior to looking to see whether heads or tails came up).  Here, the physics seemed to indicate that in a quantum process, the outcome exists in a superposition of all possible outcomes, but when it's observed, the wave function collapses into one of them, and the probabilities of the others drop to zero.

Schrödinger thought this couldn't possibly be correct, even though the mathematics was impeccable and agreed with all the experimental data (and, in fact, still stands today).  His thought experiment locked a cat in a box with a flask of poison; the flask could be broken by a remote-controlled hammer triggered by detection of a particle by a Geiger counter (particle decay and radioactivity are inherently quantum probabilistic processes).  So, is the cat dead or alive?  It was ridiculous to think it could be both (until you open the box), but that was the inevitable outcome of the quantum model.

Not only did this seem like a nonsensical prediction, a lot of physicists objected to the role of an observer.  Why should looking at something (or measuring it) affect its physical state?  And besides, what do we mean by observer?  Does it have to be conscious, or is merely interacting enough?  If a photon hits a rock, is the rock somehow "observing" it and altering its quantum mechanical state?

As a way around this, another brilliant physicist, Hugh Everett, turned the whole thing on its head by saying maybe measurement or observation doesn't collapse the wave function, it splits it -- bifurcating the universe into two branches, one in which (for example) the cat dies, and the other in which it survives.  This idea -- which gave rise to hundreds of episodes on Star Trek alone, as well as my own novel Lock & Key -- pleased some people but massively pissed off others, because it results in staggering numbers of alternate universes which then are forever walled off from each other.  The Many-Worlds Interpretation, as it has come to be called, thus appears to be intrinsically unverifiable, and another example of Wolfgang Pauli's acerbic quip, "This isn't even wrong."

Okay, so far that's just background, and probably you already knew most or all of it.  But what the article I came across this morning did was to ask a simple question:

If Many-Worlds is correct, what is it like from the point of view of Schrödinger's Cat?

Or, since people might differ on whether a cat qualifies as an observer, suppose a human is inside the box, and within any given minute, the probability of surviving is exactly one-half.  According to Many-Worlds, at every moment there is a non-zero chance of surviving and a non-zero chance of dying.  What this implies is that in one branch of the universe, you survive every time.

In other words, the Many-Worlds Interpretation seems to guarantee immortality.

Peter Byrne, who wrote a biography of Hugh Everett, danced around the issue.  "It is unlikely, however, that Everett subscribed to this [quantum immortality] view," Byrne wrote, "as the only sure thing it guarantees is that the majority of your copies will die, hardly a rational goal."  Which may well be true, but the goal isn't the issue, is it?  The reality is the issue.  Philosopher David Lewis summed it up in a lecture, in a passage that if it doesn't give you the chills, you're made of sterner stuff than I am:

As all causes of death are ultimately quantum-mechanical in nature, on the Many-Worlds Interpretation, an observer should subjectively expect with certainty to go on forever surviving whatever dangers [he or she] may encounter, as there will always be possibilities of survival, no matter how unlikely; faced with branching events of survival and death, an observer should not equally expect to experience life and death, as there is no such thing as experiencing death, and should thus divide his or her expectations only among branches where they survive.

Which brings up a rather alarming question: if some version of me survives in at least one branch of the universe, whose consciousness does that "me" represent?  The usual approach is that the "me" in some other branch is unaware of the "me" in this branch, and goes on his merry way making different decisions than I'm making; but how can there be more than just a singular "me"?  If this is true, what does "me" even mean?

And the quantum immortality argument makes this infinitely worse.  Physicist and deep thinker Max Tegmark points out that while the overall probability of your being in the "surviving branch" drops by half every minute -- and therefore, eventually becomes a really small number -- from the point of view of the "you" that has survived every branch thus far, it will still always be fifty-fifty.

Tegmark writes:

Quantum immortality posits that no one ever dies, they only appear to.  Whenever I might die, there will be another universe in which I still live, some quantum event (however remotely unlikely) which saves me from death.  Hence, it is argued, I will never actually experience my own death, but from my own perspective will live forever, even as countless others will witness me die countless times.  Life however will get very lonely, since everyone I know will eventually die (from my perspective), and it will seem I am the only one who is living forever — in fact, everyone else is living forever also, but in different universes from me.

It's not all that I'm all that fond of the idea of kicking the bucket.  I'm like my dad, who was once asked by a family friend what he wanted written on his gravestone, and he deadpanned back, "He's Not Here Yet."

But even so, can we all agree that this is a ghastly thought?

Tegmark agrees, although his objection to it -- based on the either/or nature of the thought experiment, as compared to the gradual process of many deaths -- strikes me as fairly weak.  "The fading of consciousness is a continuous process," he writes.  "Although I cannot experience a world line in which I am altogether absent, I can enter one in which my speed of thought is diminishing, my memories and other faculties fading...  I am confident that even if [a person] cannot die all at once, he can gently fade away."

All righty, but I still want to know why the physics demonstrates that this can't be true.

So that's our unsettling journey through the deep waters of quantum physics for today.  And you thought yesterday's post about "there's no such thing as local realism" was bad.  Me, I think I need to have another cup of coffee and then go play with my puppy.  He never worries about physics and philosophy.  He never worries about much of anything, far as I can tell.

What an enviable quantum state to be in.

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Escaping the bottle

Two years ago, I wrote a post about the work of Nick Bostrom (of Oxford University) and David Kipping (of Columbia University) regarding the unsettling possibility that we -- and by "we," I mean the entire observable universe -- might be a giant computer simulation.

There are a lot of other scientists who take this possibility seriously.  In fact, back in 2016 there was a fascinating panel discussion (well worth watching in its entirety), moderated by astrophysicist Neil deGrasse Tyson, considering the question.  Interestingly, Tyson -- who I consider to be a skeptic's skeptic -- was himself very accepting of the claim, and said at the end that if hard evidence is ever found that we are living in a simulation, he'll "be the only one in the room who's not surprised."

Other participants brought up some mind-boggling points.  The brilliant Swedish-American cosmologist Max Tegmark, of MIT, asked the question of why the fundamental rules of physics are mathematical.  He went on to point out that if you were a character inside a computer game (even a simple one), and you started to analyze the behavior of things in the game from within the game -- i.e., to do science -- you'd see the same thing.  Okay, in our universe the math is more complicated than the rules governing a computer game, but when you get down to the most basic levels, it still is just math.  "Everything is mathematical," he said.  "And if everything is mathematical, then it's programmable."

One of the most interesting approaches came from Zohreh Davoudi, also of MIT.  Davoudi is studying high-energy cosmic rays -- orders of magnitude more energetic than anything we can create in the lab -- as a way of probing the universe for what amount to glitches in the simulation.  It's analogous to the screen-door effect , a well-known phenomenon in visual displays, where (because there isn't sufficient resolution or computing power to give an infinitely smooth picture) if you zoom in too much, images pixellate.  The same thing, Davoudi says, could happen at extremely high energies; since you'd need an infinite amount of information to simulate behavior of particles on those scales, glitchiness in extreme conditions could be a hint we're inside a simulation.  "We're looking for evidence of cutting corners to make the simulation run with less demand on memory," she said.  "It's one way to test the claim empirically."

The reason this comes up is because of a recent paper by Roman Yampolskiy (of the University of Louisville) called, simply, "How to Hack the Simulation?"  Yampolskiy springboards from the arguments of Bostrom, Kipping, and others -- if you accept that it's possible, or even likely, that we're in a simulation, is there a way to hack our way out of it?

The open question, of course, is whether we should.  As I recall from The Matrix, the world inside the Matrix was a hell of a lot more pleasant than the apocalyptic hellscape outside it.

Be that as it may, Yampolskiy presents a detailed argument about whether it's even possible to hack ourselves out of a simulation (and answers the question "yes").  Not only does he, like Tegmark, use examples from computer games, but also describes an astonishing experiment I'd never heard of where the connectome (map of neural connections in the brain) of a roundworm, Caenorhabditis elegans, was uploaded into a robot body which then was able to navigate its environment exactly as the real, living worm did.  (The more I think about this experiment, the more freaked out I become.  Did the robotic worm know it was in a simulated body?)

Evaluating the strength of Yampolskiy's technical arguments is a bit beyond me, but to me where it becomes really interesting is when he gets into concrete suggestions of how we could get a glimpse of the world outside the simulation.  One method, he says, is get enormous numbers of people to do something identical and (presumably) easy to simulate, and then simultaneously all doing something different.  He writes:

If, say, 100 million of us do nothing (maybe by closing our eyes and meditating and thinking nothing), then the forecasting load-balancing algorithms will pack more and more of us in the same machine.  The next step is, then, for all of us to get very active very quickly (doing something that requires intense processing and I/O) all at the same time.  This has a chance to overload some machines, making them run short of resources, being unable to meet the computation/communication needed for the simulation.  Upon being overloaded, some basic checks will start to be dropped, and the system will be open for exploitation in this period...  The system may not be able to perform all those checks in an overloaded state...  We can... try to break causality.  Maybe by catching a ball before someone throws it to you.  Or we can try to attack this by playing with the timing, trying to make things asynchronous.

Of course, the problem here is that it's damn near impossible to get a hundred people to cooperate and follow directions, much less a hundred million.

Another suggestion is to increase the demand on the system by creating our own simulation -- a possibility Bostrom and Kipping considered, that we could be in a near-infinite nesting of universes within universes.  Yampolskiy says the problem is computing power; even if we're positing a simulator way smarter than we are, there's a limit, and we might be able to exploit that:

The most obvious strategy would be to try to cause the equivalent of a stack overflow—asking for more space in the active memory of a program than is available—by creating an infinitely, or at least excessively, recursive process.  And the way to do that would be to build our own simulated realities, designed so that within those virtual worlds are entities creating their version of a simulated reality, which is in turn doing the same, and so on all the way down the rabbit hole.  If all of this worked, the universe as we know it might crash, revealing itself as a mirage just as we winked out of existence.

In which case the triumph of being right would be cancelled out rather spectacularly by the fact that we'd immediately afterward cease to exist.

The whole question is as fascinating as it is unsettling, and Yampolskiy's analysis is at least is a start (along with more technical approaches like Davoudi's cosmic ray experiments) toward putting this on firmer scientific ground.  Until we can do that, I tend to agree with theoretical physicist James Sylvester Gates, of the University of Maryland, who criticizes the simulator argument as not being science at all.  "The simulator hypothesis is equivalent to God," Gates said.  "At its heart, it is a theological argument -- that there's a programmer who lives outside our universe and is controlling things here from out there.  The fact is, if the simulator's universe is inaccessible to us, it puts the claim outside the realm of science entirely."

So despite Bostrom and Kipping's mathematical argument and Tyson's statement that he won't be surprised to find evidence, I'm still dubious -- not because I don't think it's possible we're in a simulation, but because I don't believe that it's going to turn out to be testable.  I doubt very much that Mario knows he's a two-dimensional image on a computer monitor, for example; even though he actually is, I don't see how he could figure that out from inside the program.  (That particular problem was dealt with in brilliant fashion in the Star Trek: The Next Generation episode "Ship in a Bottle" -- where in the end even the brilliant Professor Moriarty never did figure out that he was still trapped on the Holodeck.)

So those are our unsettling thoughts for the day.  Me, I have to wonder why, if we are in a simulation, the Great Simulators chose to make this place so freakin' weird.  Maybe it's just for the entertainment value.  As Max Tegmark put it, "If you're unsure at the end of the day if you live in a simulation, go out there and live really interesting lives and do unexpected things so the simulators don't get bored and shut you down." 

Which seems like good advice whether we're in a simulation or not.

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