On “Do-Overs”

I love “do-overs”. Not because I want to change anything in particular about my life, but because they are so rare, and so interesting. On my way to Vancouver on Monday, I got to do one.

We (myself and the other passengers) boarded our flight at Denver. I usually get on the plane early, and so have the change to watch people go through their routines of boarding and all that entails. After that was all, the plane full of passengers waited for the plane to get ready, doors to close, and so forth. It did not happen. After a while, the pilot came on and explained that they were trying to fix the radio, and it would be another half an hour. So we waited. After another long while, the pilot came on and said that they did not expect that the radio would get fixed in a timely manner after all, and so they were going to try something else. We would “de-plane” (a word I hate by the way – what is wrong with the perfectly good word “disembark”?) and all make our way to another gate where eventually another plane would arrive, and we’d take that one. It would be exactly the same type of plane. We would keep our ticket stubs and just re-board an hour and a half later.

I wandered for a bit, found something not too repulsive to nibble on (seems to get harder and harder in some airports), was disappointed by the meagre bookstore once again, and otherwise killed some time. Then the boarding started again. A “do-over”. Everybody would be going back to the same seats, it would be exactly the same people as before. How interesting it will be to see what would be different and what would stay the same!

  • Will people put their baggage in the same place? (I know, it might seem a little odd that I notice where people put their bags, but I seem to – well, some of the nearby stuff).
  • Will they enter in roughly the same order as before?
  • Will that cute family come on in the same order as before? No, the little girl is not giggling and running ahead this time. Her older sister leads the way, and she almost bumps her face into the bag of the tall man who stopped suddenly in front of her. She makes a melodramatic twisted face at this, to herself, and I smile at this. She sees me smile at her personal drama.
  • Will that overly-muscled guy again fail to help that tiny woman heave that huge case up into the overhead bin?
  • Will I smile at that same striking woman this time? Would she look sharply away this time as she did before?
  • Will we take off this time around?
  • Is anyone else thinking about the do-over details, or is it just me?

This time I know in advance that the fascinating, beautiful woman of my dreams won’t be sitting next to me. She never does, of course. (Except that one time). I know this since last time, 90 minutes ago, it was the grey-haired business man. Pleasant enough guy. So I know I won’t be playing that usual guessing game where you look into the faces of the people who come in and see how soon you can determine that they will or won’t be sitting next to you.

All of this leads me to think about parallel universes a bit. Not too much, but a bit. Parallel in the sense of being very similar except for slight details. People like to speculate about them, including asking questions about whether they really exist in some meaningful sense. It’s fun to think about, but I’m pretty sure that at the human scale two such universes would be unlikely to remain similar for very long. I imagine they’d get very different from each other rather rapidly, just like the little girl in the family not coming in first the second time around, the older sister doing so instead and bumping, almost, and so forth. In physics terms, we’d think of parallel universes as similar-but-different in a more fundamental sense. The laws of physics could be similar, but with slight differences brought about by different values of certain fundamental constants perhaps. But there’d not likely be similar copies of you or me walking around, making ever so slightly different choices from the ones we’re making today, indefinitely into the future.

Do parallel universes really have a role in real physics, as opposed to fun movie scenarios or TV shows? I don’t know. Most likely nobody knows right now. Some people are thinking about it. There may be ways in which their existence could be meaningful even without having some means of ever visiting another one and returning to tell the story in some reproducible way. Perhaps there will be properties of our universe – you know, the real measurable one – that somehow rely upon the existence of other universes. Some quantities we cannot explain without an ensemble of other other universes. Right now, that’s all total speculation, but it is interesting to think about.

Hmm…. anyway, this has all reminded me of a beach shoot for a TV show I did some months back that I have not yet told you about. It was all about parallel universes, you see. More on that later. I’m back in Aspen now and back to work and retreat mode.


Bookmark the permalink.

11 Responses to On “Do-Overs”

  1. Jude says:

    A Twilight Zone episode would have you disembarking from plane after plane, with subtle differences in the boarding order, and none of the planes ever managing to take off.

  2. Clifford says:

    Yes, good ‘ol Twilight Zone. Pity there’s nothing quite like that being made any more (as far as I know). Maybe we’re all to sophisticated now. Some of them were so simple, but clever… no super effects, a bit clunky, but so effective.



  3. Plato says:

    I was thinking more of the time travel scenarios.

    Kurt Godel

    In the late 1940s, Gödel demonstrated the existence of paradoxical solutions to Albert Einstein’s field equations in general relativity. These “rotating universes” would allow time travel and caused Einstein to have doubts about his own theory. His solutions are known as the Gödel metric.

    But as to the “extra journey” through the airport, that book store is not as exceptional as you say.

    Did you get a chance to visit with Moshe?

  4. Clifford says:

    Huh? I did not say it was exceptional, but exactly the opposite. A single tiny bookstore for an entire huge terminal, with a poor selection of books.

    The Godel metric is cute, but nobody knows if it has anything to do with physics.



  5. linda says:

    hi, nice post
    just wondering,
    could you give an example of a physical quantity which would be explainable only if one assume the existance of ensembles?!

  6. Clifford says:


    Thanks. Well, if I had a really good idea I’d have written it up by now, but all I’m saying (and this is an idea that’s been around in one shape or form for a long time now) is that there are possibly quantities that cannot be intrinsically computed from first principles using only theories that refer to one universe. The cosmological constant is one example of a parameter of the universe we have no clue as to why its value is one number or another. All we can do is measure it and use it as input into our theories. There’s actually nothing wrong with that…. we’ve been doing that process in science for many centuries and probably always will. On the other hand, maybe one day we’ll figure out a smart theory that can do it, or maybe it cannot be computed without a theory that takes into account other universes. There may be other such numbers/parameters. Maybe the coincidence problem will be cast into such a framework one day.


  7. linda says:

    i see
    i think condensed matter theorists work with ensembles more often than anybody else, and since they are closer to string theorists than particle phenomenologists techniques-wise, collaborations between string and condensed matter theorists will be fruitful, may be that is what we need for another revolution

  8. Mister Pompous Language Pedant says: You can’t disembark from a plane because it’s not a bark. He continues in the same vein, saying that the words should be emplane and disemplane, however.

  9. Supernova says:

    The Denver airport is not bad as airports go, though I agree with you that the bookstores could be vastly improved. Best food I’ve found is at Chef Jimmy’s in Concourse A — they make a very good chicken salad/noodle bowls with lots of fresh greens and red peppers. Perfect for long flights when you know you’re not going to meet another vegetable for hours.

  10. stevem says:

    I hear airlines are doing all they can to strip weight of their planes to combat rising fuel costs which are hurting them badly. Airport book stores=cheap or trashy paperbacks usually. I think if you were in an ep of Twilight Zone you would see a creature sitting on the wing of the plane and no-one else would;)

    The Godel solution is globaly non-hyperbolic so has closed timelike curves and is probably physically unrealistic. Godel was featured at length in a recent bbc quality documentary called “Dangerous Knowledge” about the life and work of some mathematicians who went insane or committed suicide (Cantor, Godel, Boltzmann and Turing).


    And yes, I do spend too much time on youtube;)

  11. Plato says:

    I said,”But as to the “extra journey” through the airport, that book store is not as exceptional as you say. Must be my writing.

    Thanks Stevem for further elaborating.

    Clifford:There may be ways in which their existence could be meaningful even without having some means of ever visiting another one and returning to tell the story in some reproducible way.

    I think there is Clifford, “as of natural consequence” we do relive the events we create, and we do assess what we have done. Now of course, as to the physics?

    quadrupole pattern of statistical anisotropy

    If we are to see such patterns that establish themselves in this pictorial sense above, what would have been it’s motivation? Does this give us a geometry and inclination to the physics, as this universe is expressed?