I was recently in danger of my life (really). Out of nowhere last fall I found myself thrust into a serious medical situation requiring immediate surgery, followed by an arduous period of recovery. My chances were good, but by no means certain.

Now I’m fine. In that disorienting manner of 21st century life, a disaster that would have quickly snuffed any of my progenitors over the past 200,000 years was corrected by modern medical intervention, and – albeit with no small effort – I found myself plunked back into my previous existence, once again fit and healthy. Things broke for me in just the right way. The required technology was available; I was in the right place geographically, and financially, to take advantage of it; I had been exercising and eating well for many years, allowing my body to handle the stress; nothing untoward took place.

And yet any number of slips could so easily have spelled my end. People don’t come back from anesthesia. They develop clots that shoot into their brains. They don’t get to emergency rooms in time and bleed out on the gurney; and so on, and on. It seems a little odd—can one experience survivor guilt regarding oneself?—that everything went so smoothly.

But then, I realized, of course it did; Hugh Everett already figured that out.



How? By postulating the existence of multiple parallel universes, each taking off in a new direction every time a wavefunction is collapsed. This is the (in)famous Many-Worlds Interpretation of QM, in which an incredibly huge number of realities contains an equally huge number of Me’s, each of which is experiencing a slight variation on my story. Thus I will necessarily live an astonishingly long life; in fact, one of record-breaking length; indeed, I am going to live as long as it is physically possible for me to live (this may mean centuries). And so will you.

But surely people perish! the voices cry -- every day, by all the terrible ways of which we know. That is unquestionably so. But the point is, none of those people are you . . . and they can’t be.

To see how we get there, consider for a moment the admittedly metaphysical suggestion that at each turn, every possibility allowed by physics is realized in some kind of higher space, making “Me” a more spread-out concept than we generally think it to be. From your perspective I may be run over by a cab tomorrow and cease to exist; very good. From my perspective lightning might blast you to cinders in the next thunderstorm. But from your perspective, *you* cannot be killed that easily, because in a Many-Worlds universe there is another you who stepped back just in time. And that you is still you; except that when *this* you died, *that* you survived. It turns out you didn’t disappear when the lightning flashed; not in the larger sense of You. (Notice that had you both survived but in different ways, that person would no longer be You, but an alternate version whose world-line diverged from yours at that point.)



Now, that surviving You may immediately fall on a pair of scissors cutting out Valentines. But somewhere in the Many Worlds they were those child-safe scissors with the rounded ends.

*That* surviving you gets drunk and stumbles into the path of a wrecking ball; but another You, round scissors still safely in pocket, sneezes at just the right moment to duck.

A trillion trillion deaths may come to different version of you – indeed, they all *do* – and yet none of them stops You, because some version necessarily escapes them all. Whichever becomes the most absurdly lucky, getting every break, making it to a record-setting old age, is the final You. Identical to the others except in its bizarre tendency to avoid mortal shock, that You will live as long as it is physically possible to do so. And that’s the You who is reading this blog post right now.

Having stumbled myself across this happy (?) observation, I was crestfallen to discover that it is already well-known: this is the notion of “Quantum Immortality.” Pity – although I suppose in some branch of the multiverse I got there first.

There’s a caveat to all this speculation, of course. This scenario says nothing at all about *happy* life, except insofar as happiness increases one’s tendency to survive. The severed woman’s head in The Brain That Wouldn’t Die was still alive, so if it’s possible that that kind of technology could intersect with you at any point, and if that you outlives all the others, then that’s what You’ll do. The physicist who attempts the Quantum Suicide Experiment, by the way, should remember that many versions of him will only be maimed by the gunshot, and live long lives of bitter regret, wishing they had gone into a less speculative field.

And then, isolated as we are by our own perspectives, our loved ones will still perish around us at the usual heartbreaking rate (forgive me; even brief time in a hospital bed sends one toward morose meditation). But we all have the cold comfort of knowing that tragically shortened lives come only to others.

If Everett – who must have been surprised to find himself live longer than anyone else in history -- was right.

image: ell brown

this post has been edited by the author since its original submission

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Dear William,

It is good that you are still with us; my prayers go out to you and your family.

If you feel up to it, I'd like to use Occam's razor and take a hack at the Many Worlds Interpretation and Quantum Immortality. I will give you a fleeting target to strike at merely by saying that there is only one biological 'you'; the other parts of you will always survive the loss of the biological you.

Can you explain how quantum eigenstates can produce entire universes out of nothingness, yet hide their gravitational effects as they divide into separate universes?

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I have some problems with the quantum suicide (QS) idea (while accepting the MWI).

a) You had surgery, but if QS is true, why did the anesthesia work? The QC logic can just as well be applied to temporary unconsciousness leading to the conclusion that you should not experience losing consciousness.

b) If the answer to a) is that the unconscious state does not count only if it will never become conscious, then that looks to be an ad hoc rule that you cannot formalize in the usual way. Suppose you do a variant of the QS experiment in which you can become unconscious instead of dying, so after the experiment you end up in the state:

1/sqrt(2) [|conscious) + |unconscious)]

Then suppose that |unconsious) will be revived, but only after a billion years. Then whether or not that revival of you a billion years later will really happen is supposed to be relevant for assigning the correct probsbility to

|conscious)? That is hard to believe!

I think it is far more natural to assign a probability of 1/2 to |conscious), irrespectective of how the state |unconscious) will end up evolving. The stste

|unconscious) has an amplitude of 1/sqrt(2) and it keeps on evolving under unitary time evolution which preserves the norm of the state. If you are not revived (or with prbsbility less than 1), then that means that the total probability of being alive at all ofter the QS experiment is less than 1.

c) The QS implicitely assumes that the whole multiverse is evolving in time. That is a rather unnatural idea. How on earth can one define a present moment that should be valid not only for our vast universe (which is already untenable) but also for the whole multiverse? It is far more natural to assume that the whole multiverse is static, i.e. the wavefunction of the unverse stays invariant under time evolution.

Then what we experince to be time evolution is what you get if you apply the time evolution operator to only that particular sector of the multiverse we are in. This leads to the picturew of the branching multiverse, but this is then only a local picture. Globally there is no branching, the whole thing stays exactly the same.

But then the probsbility that you are in some given state is determined by some amplitude extracted from that static eternal wavefunction. That amplitude has to be consistent with unitary mappings. The sector in which you survive the QS experiment has a reduced amplitude. There is no escape possible from that conclusion.

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The Many Worlds Interpretation (MWI) of quantum mechanics is not really a theory in the proper sense. This goes for any interpretation of quantum mechanics, whether Copenhagen, Bohmian “be-able,” and so forth. There is no way one can experimentally test any of these interpretations, and so far attempts to find some testable aspect of them involves an adulteration of quantum theory. MWI is popular these days, or in a sense “hip,” and it does permit one to solve a range of problems involving quantum information, but it is not an effective scientific hypothesis, for there is no way one can probe some subquantal aspect of nature to test these things. Deutsch and others have proposed some scalar field effects and other means by which MWI can be probed, but this in effect changes quantum physics in a way which is not satisfactory.

So while MWI might predict there are a vast number of copies of “me” which exist in the quantum superspace of existence, the idea I will after death hop on another track, say maybe from the first quantum event involving conception (thought of as the instantiation of information in a general wave “collapse”) these idea can’t really be tested. So quantum immortality is a metaphysics, not much more empirically based than other immorality ideas.

Cheers LC

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Logically, say this is the moment called now, in 2010, a moment ago 2010 is gone, there is no evidence that it exists, still exists? Even another universe pathway would have to have a "now" and a "past"...so how does one monouvre onself into a domain that has not a single molecule?..there is no past in any Universe, every Universe that exists or is theorized to exist can only have a "now"?

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Quantum interpretations are ways we try to make sense out of something which transcends our sensory capacity. Quantum mechanics in many ways is very simple. It is a theory of linear waves, with Hermitian eigenvalues and unitary transformations. In some ways nature could not possibly be simpler. Yet it does not make sense when detected from a classical perspective. We have all these issues of collapse and state reductions which seem to violate quantum theory, as these are not unitary, and we accuse quantum theory for the problem. So we try to patch up quantum “weirdness” with these various interpretations. In some sense this is looking at things upside down. What is strange is the classical world and how it somehow emerges from the quantum substratum of the universe.

Quantum interpretations are not falsifiable, for to test them requires looking by mysterious means behind what we might call the quantum horizon of uncertainty. So far at least we have no understanding of how that is possible. Interpretations might have their utility to some extent. Even Bohm’s approach to QM has great potential as a way of working on quantum chaos problems, even if it is terrible in the relativistic domain where particles are generated at high energy. So these don’t appear falsifiable in any direct way.

Sadly physics has gotten rather skewed down the road of interpretationism. Even in statistical mechanics there are heated arguments over whether the Jaynes approach with Bayesian statistics is or is not preferable to the ensemble approach initiated by Boltzmann which has a frequentist interpretation. This seems to my mind to lead to a sort of sterility to the study of physics.

Cheers LC

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In order to explain electromagnetism, gears and elastic ether were proposed. Special relativity seems to work well without these, replacing them with vector and tensor fields on a geometric spacetime. Relativity seems not to need interpretations (it has good geometrical interpretations though).

I do not advocate that QM does not need interpretation either. But this is not a problem of interpretation, what we need are answers. The problems of measurement, of classical level, of apparent state vector reduction maintaining all conservation laws characteristic to the unitary evolution, all these need genuine answers, and we don't have them in the standard QM.

It is often claimed that quantum mechanics makes perfect sense from mathematical viewpoint, but people need interpretations because they cannot think too abstract. But in fact there is no consistent mathematical solution to these problems of quantum mechanics. Only operational rules of what we get in various conditions. If QM would have a mathematical answer to these problems, no matter how abstract, it would be enough, like it was for the theory of relativity.

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It think its helpful to try to make real world analogies for QM, relativity, etc. It leads us to clues; to good questions that can give fruitful answers. What's wrong with using both hemispheres of our brain to explore physics? What's wrong with using both our creativity as well as our logic?

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ET Phone Home

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William,

Glad you are safe and sound! You're in Boston, right? Indeed, we are spoiled in New England with excellent medical facilities.

Ian

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If there are many parallel universes then, going back some 100 years to the time of Planck and Einstein, (quanta and photons), consider a Universe where Planck's Law (or variation of it) is an exact mathematical identity (a tautology) that describes the interaction of energy. To enter this parallel Universe and the Physics that describes it, click here!

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William,

Glad to find you back on this timeline with us, healthy and happy.

At least one physicist (Hawking?) that I recall, pronounced MWI "trivially true." I think it does come down to statistical interpretation. That is, as Lawrence alludes to, Bayesian analysis gives us the freedom to believe--if we assign value to personal belief, there is always 100% probability that you survived.

The constraints of mechanics are less generous. In a frequentist world--and ours does appear to be such a world--the dice are never at rest until one reads them. So one will never know that one's survival dipped to probability zero.

I know it to be a myth that one never dies in one's dreams, because I have had such an experience. No, I didn't wake up in my bed when I died; I had the distinct experience of fatal injuries, of losing consciousness, of reawakening in a different location, all within the dream. When I did wake into this world, it was with a profound sense of well being.

I agree with you, William. All things considered, survival is 100% probable.

We can never simultaneously read all the faces of all the dice when they are rolling; we do, however, know that they are loaded in our favor until we die. And how could we expect to know what death is, when we haven't even yet figured out what life is?

Tom

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