Thursday, July 2, 2009

Or maybe we just suck

I recently read Michio Kaku's "Physics of the Impossible" - quite a good book, I highly recommend it. One of the sections was on time travel, and he repeated Stephen Hawking's observation that if time travel were ever to be possible, then why aren't we awash in time-traveling tourists now?

This is sort of taken for granted in this book, as elsewhere. And yet I cannot help but think that there are some assumptions there that ought not go unchallenged. It seems to me that there's a limitation on how long anything in the present day is going to be interesting to people in the future. There's really very little going on - it all seems important to us now, but in fifty years people will probably be mostly interested in a relative handful of things. In a hundred years, it seems to me that maybe only a few dedicated historians would come here, maybe to watch Obama's inauguration in person.

But it seems more likely to me that it'll take several hundred years, or thousands of years, to develop a working time machine. Who knows how long it would take to make the technology available to more than a lucky few. It took fifty years for low-orbital space travel to become available to a half dozen wealthy tourists, who had to train hard on the ground, then keep out of the way during a short mission. Who are their equivalents, I wonder, who are also more keenly interested in events of 1000 years ago than 2000 years ago, or 500? Why come back to the early 21st Century when there were such interesting things happening in Rennaisance Italy or in Roman-occupied Judea? (After all, a time machine, a camcorder, and an Aramaic-to-Chinese dictionary could clear up more than a few obnoxious arguments)

Let's face it, we're boring, and that's a strike against us. Speaking from a tourism point of view, we're the temporal equivalent of Ohio. Sure, we've got Obama's inauguration and the Iranian election, but in the thousand-year view of things they don't even amount to that huge ball of yarn.

On top of that, we're watching for time travelers. Or at least, we've managed to build ourselves a neat little surveillance society with lots of cell phone cameras, the concept of time traveling tourists, and "healthy" doses of novelty-seeking and paranoia.

Finally, it takes a special kind of mind to see today's successful experiments with visible-light invisibility and other negative-optics shenanigans, hypothesize a future civilization capable of time travel as a leisure activity... and still think that we'd actually be able to tell when the handful of bored tourists actually does show up.


  1. Testing comments (others have had trouble with this)

  2. Ok, trying to repost this comment from a different browser... let's see if I can reconstruct it.

    Halfway through, I was thinking "but there's not much evidence of time travelers at momentous periods in history either", but then I independently came to the same thought you did, that time travelers hiding themselves probably wouldn't be difficult. Still, even if the stealth technology is easy, never having seen them also implies the existence of a sort of temporal Prime Directive, with near-perfect enforcement. It's the enforcement (across all time-travelers from all time with destinations prior to the present day) that seems tricky, unless we've also evolved into a uniform hive-mind by that point.

    On the other hand, it's also possible that time traveling simply splits the timeline. In fact, if you subscribe to the version of the many-worlds hypothesis that calls for a new universe with each quantum decision, it seems likely that the chances of ending up in a universe split off by a time machine are infinitesimally small. Of course, such a scheme could also make it problematic/impossible to return to one's "home" timeline, which could have a distinct disincentive effect on attempting such things as well.

  3. Sure, there are lots of other possibilities, including splitting the timeline.

    But the way I see it, there are a couple variables at play here at any given place and time.
    First: interestingness to potential time travelers from whenever time travel becomes possible.
    Second: ability of time travelers to make themselves inconspicuous
    Third: ability of temporal locals to recognize time travelers even if they are perfectly visible. Even if not invisible, if you're somewhere where such interesting things are happening that time travelers might show up, are you going to notice them?
    Fourth: likelihood of the wider world finding out about (and believing) a successful ID. (For example, if you were absolutely convinced that you just met a time traveler, how much success would you have in making that known?)

    In other words, what are the chances that they:
    * Show up in the first place
    * Are seen
    * Are recognized
    * Are exposed (and believed)
    And it seems to me that the probabilities here are rather astonishingly low. And if there are relatively few time travelers in the first place, then it seems to me they stand a very good chance of never being exposed as such.

    I don't think you need any kind of Prime Directive to manage this sort of thing, either. As long as it's relatively difficult/expensive to travel back in time, then simple screening ought to suffice: don't send anyone back who's planning to (or likely to) out themselves as time travelers. Or, send a chaperone or two. Or do like we're doing now with space travel: send highly-trained professionals with video cameras.

  4. Of course time travel is possible. What do you think caused the Roswell crash?

  5. Katyrnyn: cell phones while flying

  6. [Hmm, that posted with my user name instead of my display name. Curious.]

    Cell phones while flying: That's why the aliens bumped into all the flying time machines!

    To approach this from a more serious mindset: Our government(s) did a splendid job of destroying (any) evidence by their research and cover-ups of the (alleged) Roswell Incident. Should a future entity decide to research (what might be) the first recorded modern "contact" between earthlings and beings from another world, they would need to witness and record the event instead of relying upon contaminated evidence. [Perhaps they need to prove in an interstellar court of law that one species or another violated contact restrictions?] It would stand to reason that more than one party might be interested in becoming witnesses to said (possible) event, all using "cloaked" time machines. And it is not entirely inconceivable that (minus any advanced traffic control systems) one of the observers might have collided with another object. It is also not inconceivable that the remains (possibly) recovered by our government(s) were of the future observers, and not of some other interstellar species. [Thereby absolving the Antarans. Unless, of course, said species was the one that collided with the "witnesses."] That might also explain the ferocity of the (alleged) cover-up.

    But of course we can't prove that time-travel does or does not exist, otherwise Issac Newton would have beaten us to it and this discussion would be moot. Unless he was the traveler, deciding to help humanity while escaping a future persecution by living in the past. And perhaps Einstein; his name is obviously fabricated. And Einstein's move would fit well with the Universe's sense of irony.

  7. Nah, the Roswell incident was a hoax, intended to draw attention away from the Osage incident.