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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Wibbly-wobbly...

Have I told you my favorite joke?

Heisenberg and Schrödinger are out for a drive, and a cop pulls them over.

The cop says to Heisenberg, who was driving, "Hey, buddy, do you know how fast you were going?"

Heisenberg says, "No, but I know exactly where I am."

The cop says, "You were doing 70 miles per hour!"

Heisenberg throws his hands up in annoyance and says, "Great!  Now I'm lost."

The cop scowls and says, "Okay, if you're going to be a wiseguy, I'm gonna search your car."  So he opens the trunk, and there's a dead cat inside.

The cop says, "Did you know there's a dead cat in your trunk?"

Schrödinger says, "Well, there is now."

*brief pause so you can all stop chortling*

The indeterminate nature of reality at the smallest scales always tends to make people shake their head in wonderment at how completely weird the universe is, if they don't simply disbelieve it entirely.  The Uncertainty Principle, peculiar as it sounds, is a fact.  It isn't a limitation of our measurement technique, as if you were trying to find the size of something small and had a poorly-marked ruler, so you could get a more accurate number if you found a better one.  This is something fundamental and built-in about reality.  There are pairs of measurements for which precision is mutually exclusive, such as velocity and position -- the more accurate your information is about one of them, the less you can even theoretically know about the other.

Likewise, the collapse of the wave function, which gave rise to the story of the famous (but ill-fated) cat, is an equally counterintuitive part of how reality is put together.  Outcomes of purely physical questions -- such as where a particular electron is at a given time -- are probabilities, and only become certainties when you measure them.  Again, this isn't a problem with measurement; it's not that the electron really is in a specific location, and you just don't know for sure where until you look.  Before you measure it, the electron's reality is that it's a spread-out field of probabilities.  Something about interacting with it using a measuring device makes that field of probabilities collapse into a specific location -- and no one knows exactly why.

But if you want your mind blown further -- last week in a paper in Physical Review Letters we found out how long it takes.

It turns out the wave function collapse isn't instantaneous.  In "Tracking the Dynamics of an Ideal Quantum Measurement," by a team led by Fabian Pokorny of Stockholm University, the researchers describe a set of experiments involving "nudging" a strontium atom with a laser to induce the electrons to switch orbits (i.e. making them assume a particular energy, which is one of those quantum-indeterminate things like position).  The fidelity of the measurement goes down to the millionths of a second, so the scientists were able to keep track of what happened in fantastically short time intervals.

And the more they homed in on what the electron was doing, the fuzzier things got.  The theory is that as you get down on those scales, time itself becomes blurred -- so the shorter the time interval, the less certain you are about when exactly something happened.

"People assume that time is a strict progression from cause to effect, but actually, from a non-linear non-subjective viewpoint, it's more of a big ball of wibbly-wobbly timey-wimey... stuff." -- The Tenth Doctor, "Blink"

I don't know about you, but I thought I had kinda sorta wrapped my brain around the quantum indeterminacy of position thing, but this just blew my mind all over again.  Even time is fuzzy?  I shouldn't be surprised; for something so damn familiar, time itself is really poorly understood.  With all of the spatial dimensions, you can move any direction you want; why is time one-way?  It's been explained using the Second Law of Thermodynamics, looking at ordered states and disordered states -- the explanation goes something like this:

Start with an ordered state, such as a hundred pennies all heads-up.  Give them a quick shake.  A few will flip, but not many.  Now you might have 83 heads and 17 tails.  There are a great many possible ways you could have 83 heads and 17 tails as long as you don't care which pennies are which.  Another shake, and it might be 74/26, a configuration that there are even more possibilities for.  And so on.  Since at each turn there are a huge number of possible disordered states and a smaller number of ordered ones, each time you perturb the system, you are much more likely to decrease orderliness than to increase it.  You might shake a 50/50 distribution of pennies and end up with all heads -- but it's so fantastically unlikely that the probability might as well be zero.  This push toward disorder gives an arrow to the direction of time.

Well, that's all well and good, but there's also the problem I wrote about last week, about physical processes being symmetrical -- there are a great many of them that are completely time-reversible.  Consider, for example, watching a ten-second clip of a single billiard ball bouncing off the side of a pool table.  Could you tell if you were watching the clip backward or forwards?  It's unlikely.  Such interactions look as sensible physically in real time or time-reversed.

So what time actually is, and why there's an arrow of time, is still a mystery.  Because we certainly feel the passage of time, don't we?  And not from any probabilistic perception of "well, I guess it's more likely time's flowing this way today because things have gotten more disorderly."  It feels completely real -- and completely fixed and invariable.

As Einstein put it, "The distinction between past, present, and future is an illusion, but it is a stubbornly persistent one."

Anyhow, that's our bizarre scientific discovery of the day.  But I better get this post finished up.  Time's a wasting.

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This week's Skeptophilia book recommendation of the week is a classic -- Martin Gardner's wonderful Did Adam and Eve Have Navels?

Gardner was a polymath of stupendous proportions, a mathematician, skeptic, and long-time writer of Scientific American's monthly feature "Mathematical Games."  He gained a wonderful reputation not only as a puzzle-maker but as a debunker of pseudoscience, and in this week's book he takes on some deserving targets -- numerology, UFOs, "alternative medicine," reflexology, and a host of others.

Gardner's prose is light, lucid, and often funny, but he skewers charlatans with the sharpness of a rapier.  His book is a must-read for anyone who wants to work toward a cure for gullibility -- a cure that is desperately needed these days.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The collapse of reality

I can say with some level of confidence that I'm nowhere near smart enough to be a philosopher.  Or, honestly, even to read most philosophical treatises with understanding.

An acquaintance of mine is a Ph.D. in philosophy, and she showed me a bit of her dissertation.  It was a kind gesture, but I read the piece of it she sent me with the same expression my dog gets when I try to explain something to him that's completely beyond his grasp, like why I don't want to play ball when we're in the middle of an ice storm.  You can tell he really wants to understand, that he would if he could, and that he feels bad that it makes no sense to him, but the whole thing only registers enough to trigger the Canine Head-Tilt of Puzzlement.

So with that disclaimer out of the way, I'm going to leap into deep waters surrounding an experiment that was the subject of a paper in arXiv last month that -- according to an article in MIT Technology Review -- shows that there's no such thing as objective reality.

The paper, entitled, "Experimental Rejection of Observer-Independence in the Quantum World," by Massimiliano Proietti, Alexander Pickston, Francesco Graffitti, Peter Barrow, Dmytro Kundys, Cyril Branciard, Martin Ringbauer, and Alessandro Fedrizzi, working at Heriot-Watt University (Edinburgh, Scotland), investigates a little-known conundrum of quantum mechanics called the Wigner's Friend Paradox.  This one adds a new layer onto the famous Schrödinger's Cat Paradox, which seems to imply that something can be in two opposing states at once until someone observes it and "collapses the wave function."

Here's the idea of Wigner's Friend (named after Nobel Prize-winning physicist Eugene Wigner).

Let's say there's a single photon being studied in a laboratory by a colleague of Wigner.  The friend observes the photon, which can be polarized either horizontally or vertically -- Wigner doesn't know which.  The friend does a measurement to find out the direction of polarization of the photon, collapsing its wave function and forcing it into one or the other, and then writes down the results -- but doesn't tell Wigner.

Then Wigner studies the same photon.  What he'll find, goes the theory, is that to Wigner, the photon is still in two superposed states at the same time.  Ergo, Wigner and his friend observe the same real phenomenon, and they come up with different answers about it.

And they're both right.

This seems like some kind of trickery, but it's not.  Reality for Wigner and his friend are demonstrably different.  This opens up a particularly snarly (and bizarre) problem called the "consciousness causes collapse" interpretation of quantum mechanics, and that's where the waters get even deeper.

[Image is in the Public Domain]

In a nutshell, here's the problem.  The collapse of the wave function happens because of interaction with an observer, but what counts as an observer?  Does the observer have to be conscious?  If a photon strikes a rock, with a particular result in terms of interacting with the rock's atoms, is the rock acting an observer?  To physicist Pascual Jordan, this seems to be stretching a point.  "[O]bservations not only disturb what has to be measured, they produce it," Jordan said.  "We compel [a quantum particle] to assume a definite position...  [therefore] we ourselves produce the results of measurements."

Which prompted Einstein himself to respond that the Moon did not cease to exist when we stopped looking at it.

Despite Einstein's scoffing, though, it seems like that's exactly the sort of thing Wigner's Friend suggests.  The Proietti et al. paper is unequivocal that the "observer problem" can't be dismissed by saying that everything, even inanimate matter, could be an observer, because it requires a sentient entity recording the results of the experiment to produce the effect.  The authors write:

The scientific method relies on facts, established through repeated measurements and agreed upon universally, independently of who observed them.  In quantum mechanics, the objectivity of observations is not so clear, most dramatically exposed in Eugene Wigner's eponymous thought experiment where two observers can experience fundamentally different realities.  While observer-independence has long remained inaccessible to empirical investigation, recent no-go-theorems construct an extended Wigner's friend scenario with four entangled observers that allows us to put it to the test.  In a state-of-the-art 6-photon experiment, we here realise this extended Wigner's friend scenario, experimentally violating the associated Bell-type inequality by 5 standard deviations.  This result lends considerable strength to interpretations of quantum theory already set in an observer-dependent framework and demands for revision of those which are not.

The MIT Technology Review article outlines how earthshattering this result is.  The author writes:

[T]here are other assumptions too.  One is that observers have the freedom to make whatever observations they want.  And another is that the choices one observer makes do not influence the choices other observers make—an assumption that physicists call locality. 

If there is an objective reality that everyone can agree on, then these assumptions all hold. 

But Proietti and co.’s result suggests that objective reality does not exist.  In other words, the experiment suggests that one or more of the assumptions—the idea that there is a reality we can agree on, the idea that we have freedom of choice, or the idea of locality—must be wrong.

This is the point where my brain simply rebelled.  I've always considered myself a staunch materialist, although (as I said before) I'm well aware both of the fact that there are philosophical arguments to the contrary and that most of them are way beyond my mind to comprehend.  But I've been able to effectively ignore those arguments because science -- my touchstone for reality -- has always seemed to me to support a materialist view.  This table, this desk, this coffee cup all have a realness independent of me, and they would be there substantially unchanged if I weren't looking, or even if I ceased to exist.

But the truth is, as usual, more complex than that.  The hard-edged materialism I've always found so self-evident might not just be arguable, but simply wrong from a scientific basis.  Perhaps our consciousness creates reality -- a view espoused by mystics, and typically rejected by your stubborn science-types (like myself).

I don't know if I'm quite ready to jump there yet.  As the MIT Technology Review article said, it may be there are loopholes in the Wigner's Friend experiment that haven't been uncovered yet.  But one by one those options are being eliminated, with the result that we materialists might be forced to reconsider, if not completely overturn, our view of the world.

All of which makes me feel like I want to hide under my blanket until it all goes away.  Or maybe just play ball with my dog, ice storm be damned.

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This week's Skeptophilia book recommendation is an entertaining one -- Bad Astronomy by astronomer and blogger Phil Plait.  Covering everything from Moon landing "hoax" claims to astrology, Plait takes a look at how credulity and wishful thinking have given rise to loony ideas about the universe we live in, and how those ideas simply refuse to die.

Along the way, Plait makes sure to teach some good astronomy, explaining why you can't hear sounds in space, why stars twinkle but planets don't, and how we've used indirect evidence to create a persuasive explanation for how the universe began.  His lucid style is both informative and entertaining, and although you'll sometimes laugh at how goofy the human race can be, you'll come away impressed by how much we've figured out.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]