Djinn and paradox

In the very peculiar Doctor Who episode "Joy to the World," the character of Joy Almondo is being controlled by a device inside a briefcase that -- if activated -- will release as much energy as a supernova, destroying the Earth (and the rest of the Solar System).  But just at the nick of time, a future version of the Doctor (from exactly one year later) arrives and gives the current Doctor the override code, saving the day.

The question comes up, though, of how the future Doctor knew what the code was.  The current Doctor, after all, hadn't known it until he was told.  He reasons that during that year, he must have learned the code from somewhere or someone -- but the year passes without anyone contacting him about the briefcase and its contents.  Right before the year ends (at which point he has to jump back to complete the loop) he realizes that his surmise wasn't true.  Because, of course, he already knew the code.  He'd learned it from his other self.  So armed with that knowledge, he jumps back and saves the day.

Well, he saves the moment, at least.  As it turns out, their troubles are just beginning, but that's a discussion for another time.

A similar trope occurred in the 1980 movie Somewhere in Time, but with an actual physical object rather than just a piece of information.  Playwright Richard Collier (played by Christopher Reeve) is at a party celebrating the debut of his most recent play, and is approached by an elderly woman who hands him an ornate pocket watch and says, in a desperate voice, "Come back to me."  Collier soon goes back in time by six decades, finds her as a young woman, and they fall desperately in love -- and he gives her the pocket watch.  Ultimately, he's pulled back into the present, and his girlfriend grows old without him, but right before she dies she finds him and gives him back the watch, closing the loop.

All of this makes for a fun twist; such temporal paradoxes are common fare in fiction, after all.  And the whole thing seems to make sense until you ask the question of, respectively (1) where did the override code originally come from? and (2) who made the pocket watch?

Because when you think about it -- and don't think too hard, because these kinds of things are a little boggling -- neither one has any origin.  They're self-creating and self-destroying, looped like the famous Ouroboros of ancient myth, the snake swallowing its own tail. 

[Image is in the Public Domain]

The pocket watch is especially mystifying, because after all, it's an actual object.  If Collier brought it back with him into the past, then it didn't exist prior to the moment he arrived in 1920, nor after the moment he left in 1980 -- which seems to violate the Law of Conservation of Matter and Energy.

Physicists Andrei Lossev and Igor Novikov called such originless entities "djinn particles," because (like the djinn, or "genies," of Arabian mythology) they seem to appear out of nowhere.  Lossev and Novikov realized that although "closed timelike curves" are, theoretically at least, allowed by the Theory of General Relativity, they all too easily engender paradoxes.  So they proposed something they call the self-consistency principle -- that time travel into the past is possible if and only if it does not generate a paradox.

So let's say you wanted to do something to change history.  Say, for example, that you wanted to go back in time and give Arthur Tudor, Prince of Wales some medication to save his life from the fever that otherwise killed him at age fifteen.  This would have made him king of England seven years later instead of his younger brother, who would have become the infamous King Henry VIII, thus dramatically changing the course of history.  In the process, of course, it also generates a paradox; because if Henry VIII never became king, you would have no motivation to go back into the past and prevent him from becoming king, right?  Your own memories would be consistent with the timeline of history that led to your present moment.  Thus, you wouldn't go back in time and save Arthur's life.  But this would mean Arthur would die at fifteen, Henry VIII becomes king instead, and... well, you see the difficulty.

Lossev and Novikov's self-consistency principle fixes this problem.  It tells us that your attempt to save Prince Arthur must have failed -- because we know that didn't happen.  If you did go back in time, you were simply incorporated into whatever actually did happen.

Timeline of history saved.  Nothing changed.  Ergo, no paradox.

You'd think that physicists would kind of go "whew, dodged that bullet," but interestingly, most of them look at the self-consistency principle as a bandaid, an unwarranted and artificial constraint that doesn't arise from the models themselves.  Joseph Polchinski came up with another paradoxical situation -- a billiard ball fired into a wormhole at exactly the right angle that when it comes out of the other end, it runs into (and deflects) itself, preventing it from entering the wormhole in the first place -- and analysis by Nobel Prize-winning physicist Kip Thorne found there's nothing inherent in the models that prevents this sort of thing.

Some have argued that the ease with which time travel into the past engenders paradox is an indication that it's simply an impossibility; eventually, they say, we'll find that there's something in the models that rules out reversing the clock entirely.  In fact, in 2009, Stephen Hawking famously hosted a time-travelers' party at Cambridge University, complete with fancy food, champagne, and balloons -- but only sent out invitations the following day.  He waited several hours, and no one showed up.

That, he said, was that.  Because what time traveler could resist a party?

But there's still a lingering issue, because it seems like if it really is impossible, there should be some way to prove it rigorously, and thus far, that hasn't happened.  Last week we looked at the recent paper by Gavassino et al. that implied a partial loophole from the Second Law of Thermodynamics -- if you could travel into the past, entropy would run backwards during part of the loop and erase your memory of what had happened -- but it still leaves the question of djinn particles and self-deflecting billiard balls unsolved.

Seems like we're stuck with closed timelike curves, paradoxes notwithstanding.

Me, I think my mind is blown sufficiently for one day.  Time to go play with my puppy, who only worries about paradoxes like "when is breakfast?" and the baffling question of why he is not currently getting a belly rub.  All in all, probably a less stressful approach to life.

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Cart both before and after the horse

Let's end the week on a happy, if surreal, note with a new experiment in quantum physics that calls into question the arrow of time.

The "arrow of time" has bedeviled physicists for decades -- why time only flows one direction, while in the three spatial dimensions you can move any way you like (up/down, backwards/forwards, right/left).  But with time, there's only one way.

Forward.

The causality chain -- that events in the past cause the ones in the future -- certainly seems rock-solid.  It's hard to imagine it going the other way, Geordi LaForge's weekly rips in the space/time continuum notwithstanding.  Although I must admit I riffed on the idea myself in my short story "Retrograde," about a woman who perceives time running backwards.  It's going to be in a short story collection I'm releasing next year, but you can read it for free on my fiction blog.

But in real life, we take the arrow of time for granted.  It's why no one was especially surprised when Stephen Hawking threw a champagne party in 2009 for time travelers, but mailed the invitations after the event was over... and no one showed up.

In any case, the arrow of time and causality chains would seem to make it certain that if there are two events, A and B, either A preceded B, A followed B, or they occurred at the same time.  (I'm ignoring the wackiness introduced by relativistic effects; here, we're simplifying matters by saying the observation and both events occurred in the same frame of reference.)

So far, so good, right?  The order of two events is a sure thing.

An experiment performed at the University of Queensland (Australia) has just proven that to be wrong.

In a paper called "Indefinite Causal Order in a Quantum Switch" that appeared last week in Physical Review Letters, by Kaumudbikash Goswami, Christina Giarmatzi, Michael Kewming, Fabio Costa, Cyril Branciard, and Andrew G. White, we find out about research that blows away causality by creating a device where a beam of light undergoes two operations -- but in our choices of A following B or B following A, what actually happens is...

... both.

[Image is in the Public Domain}

The setup is technical and far beyond my powers to explain in a way that would satisfy a physicist, but the bare bones are as follows.

Light has a property called polarization.  In effect, that means it vibrates in a particular plane.  As an analogy, think of someone holding a long spring, with the other end tied to a post.  The person is jiggling it to create a wave in the spring.  Are they waving it up and down?  Side to side?  Diagonally?

That's polarization in a nutshell.

(An interesting side-note: this is why polarized sunglasses work.  Light reflecting off a surface gets polarized in the horizontal direction, so if you have a material that blocks horizontally-polarized light, it significantly reduces glare.)

Anyhow, what Goswami et al. did was to rig up a device wherein a horizontally-polarized photon goes down a path where it experiences A before B, while a vertically-polarized one a path where it experiences B before A.  But here's where it gets loony; because of a phenomenon called quantum superposition, in which a photon can be in effect polarized in both directions at the same time, when you pass it through the device, event A happens before event B, and B happens before A, to the same photon at the same time.

Okay, I know that sounds impossible.  But in the quantum realm, seriously weird stuff happens.  It's counterintuitive -- even the eminent Nobel laureate Niels Bohr said, "[T]hose who are not shocked when they first come across quantum theory cannot possibly have understood it."  Thus we have not only loopy ideas like Schrödinger's Cat, but experimentally-verified claims such as entanglement (what Einstein called "spooky action at a distance"), an electron being in two places at once, and the fuzziness of the Heisenberg Uncertainty Principle (that the more you know about an object's velocity, the less you know about its position -- and vice versa).

Which is a deliberate setup for my favorite joke of all time.  Ready?

Schrödinger and Heisenberg are going down the highway in Schrödinger's car, Heisenberg at the wheel, and a cop pulls them over.

"Buddy," the cop says, "do you know how fast you were going?"

Heisenberg says, "No idea.  But I can tell you exactly where I was."

The cop says, "Okay, if you're gonna be a smartass, I'm gonna search your car."  When the cop opens the trunk, 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."

Ba-dump-bump-kssh.  Ah, nerd humor is a wonderful thing.

But I digress.

As impossible as quantum mechanics sounds, it seems to be true.  John Horgan, in his book The End of Science, writes, "Physicists do not believe quantum mechanics because it explains the world, but because it predicts the outcome of experiments with almost miraculous accuracy.  Theorists kept predicting new particles and other phenomena, and experiments kept bearing out those predictions."

Which is a nicer way of saying that if your common sense rebels when you hear this stuff, sucks to be you.

So as bizarre as it is, we're forced to the conclusion that the universe is a far weirder place than we thought.  Myself, I think it's kind of cool.  Despite my B.S. in physics -- and let me tell you, I was no great shakes as a physics student, and I'm convinced some of my professors passed me just so I wouldn't have to retake their courses -- my mind is overwhelmed with awe every time I read about this stuff.  I wonder, though, if it's even possible for the human mind to truly conceptualize how quantum mechanics works; we are so locked into our ordinary, classical, three-dimensional world, where first you turn the key in the ignition and then your car starts, we're completely at sea even trying to think about the fact that on some level, we can't take any of those things for granted.

So this is looking like opening up a whole new area of study.  Very exciting stuff.  And it may be naive of me, but I'm still hoping it's going to lead to a time machine.

First thing I'm going to do is crash Stephen Hawking's party, temporal paradox or no.  It may cause the universe to end, but that's a risk I'm willing to take.

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This week's Skeptophilia book recommendation is a classic, and especially for you pet owners: Konrad Lorenz's Man Meets Dog.  In this short book, the famous Austrian behavioral scientist looks at how domestic dogs interact, both with each other and with their human owners.  Some of his conjectures about dog ancestry have been superseded by recent DNA studies, but his behavioral analyses are spot-on -- and will leaving you thinking more than once, "Wow.  I've seen Rex do that, and always wondered why."

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

Echoes of the future

A couple of days ago, a reader of Skeptophilia sent me a link to a website that has a compilation of research purporting to show reverse causality -- that the future can influence the past.  More specifically, it describes experiments using random number generators that are alleged to show statistical deviations from randomness shortly before major world events (such as the 2004 Indonesian tsunami).

The website calls this effect retropsychokinesis -- that somehow, people's reactions in the future are reaching backwards and influencing past events.  The person who sent me the link accompanied it with the questions, "What do you make of this?  Can there be anything to this?"

[image courtesy of the Wikimedia Commons]

So I spent a couple of hours pawing through the links on the website, and my general reaction is: "not much" and "I don't think so."

My first reaction whenever anyone makes a claim like this is to say, "Show me the mechanism."  If you think that our global consciousness (whatever that means) can alter streams of random numbers generated in the past, then explain to me how that could work.  As far as I can see from the website, any explanations are pretty thin, usually falling back on some vague allusions to quantum indeterminacy:

The existence of this effect (if in fact it does exist) raises some very deep questions concerning the nature of time, the relationship between consciousness and objective material reality, the concept of causality, and the concept of randomness.  The much misunderstood "multiple (or parallel) universes" interpretation of quantum mechanical phenomena has been suggested as part of a model which encompasses the RPK phenomenon.  This in itself raises many important questions.  The idea of "will" is certainly related, as this is the best existing description of that which the subject uses in order to exert an influence.

The second thing, however, is to ask why -- if (for example) some kind of Disturbance in the Force prior to the 2004 tsunami altered the ordinary chain of causality -- the best it could do is to disturb some random number generators.  Seems like if there is an effect (or a cause, or whatever you'd call this), there'd be a bigger result.

Such as an awareness that a disaster was about to happen, allowing people to seek higher ground in time.

But the biggest problem is the quality of the evidence.  Dick Bierman, a RPK apologist, has a statistical analysis of the deviations that have been reported, and the results (according to Topher Cooper), are pretty earthshattering.  "The odds of this sum being this large is one chance in 630 thousand million (what us Yanks call 630 billion)," Cooper says.  "I would say that he [Bierman] was not exaggerating when he said that this is pretty strong evidence that 'something' (other than the null hypothesis) 'is going on'."

Cooper only alludes to the problem with all of this near the end of his analysis.  After going through how amazing the evidence all is he adds, with apparent reluctance, "Whether that 'something' is something interesting (e.g., paranormal) depends on an analysis of the tightness of the experimental protocols."

And therein lies the main problem with this.  Most of the experiments cited in the website, and analyzed by Bierman and Cooper, were run by one Helmut Schmidt.  Schmidt spent his entire life trying to establish proof of the paranormal, and extrasensory perception in particular, and his results are generally considered to be flawed.  As James Alcock wrote in The Skeptical Enquirer:

Schmidt’s claim to have put psi on a solid scientific footing garnered considerable attention, and his published research reported very impressive p values.  In my own extensive review of his work, I concluded that Schmidt had indeed accumulated impressive evidence that something other than chance was involved (Alcock 1988).  However, I found serious methodological errors throughout his work that rendered his conclusions untenable, and the “something other than chance” was attributable to methodological flaws.

Blunter still was the assessment by Victor Stenger, professor of physics and astronomy at the University of Hawaii:

Olshansky and Dossey argue that quantum mechanics provides a physical basis for retroactive prayer.  They refer to experiments by Helmut Schmidt in which humans attempt to mentally affect radioactive decays, which are inherently quantum events.  While Schmidt claims positive results, his experiments also lack adequate statistical significance and have not been successfully replicated in the thirty-five years since his first experiments were reported.

So predictably I'm unimpressed.  It's not that reverse causality not an intriguing idea; something like it was the genesis of my novel Lock & Key, not to mention the plots of about a dozen episodes of Star Trek: The Next Generation.

But all of those have in common that they're fiction.  If you're expecting me to buy that such a thing has a basis in reality, I'm going to need a little more than some questionable (and apparently unreplicable) experiments with random number generators.