We’re all gonna die!

I’d reconciled myself to the fact that the sun will die in about 5 billion years — time enough to get all the important stuff done, I thought — but now Chris Mims tells me we’ve only got 12 million years. I mean, that’s like going to the doctor, and he says, “Good news, Mr Myers, you’re going to live to be 90” and then he calls you up a little later and says “whoops, little slip up there, you’ve got a month to live.” It’s not good news.

The story is a bit speculative—we’ve long known that there are these very rough periodic extinctions in the fossil record, and now a few wild-eyed theoreticians suggest that it might be correlated with our system’s rotation around the galaxy, and every 60 some million years we swing around to the side that’s getting zapped a little more heavily.

Just to throw a little restraint into the guesswork, though, the mass extinction data shows considerable variability, and also the idea that we’re going to get irradiated is a little excessive. Passage through the rough side of the galaxy would be an event spanning millions of years: the earth was not sterilized in previous events, but if this were the cause, it would mean that there would be a low level increase in radiation over a very long period of time that would have stressed life to varying degrees. We do have 12 million years to manufacture lead-lined umbrellas and try to develop cosmic-ray resistant wheat. I’m just going to have to trust my great600000th-grandchildren to get their act together in time.


  1. #1 Blake Stacey
    July 28, 2007

    Yeah, my first reaction was, “What about that whole Nemesis thing?”

    It doesn’t look like too much has been happening on the Nemesis front, although apparently last year there was some talk that Sedna’s orbit might show the effects of the Nemesean gravitational pull.

  2. #2 Torbjörn Larsson, OM
    July 28, 2007

    Ever since the dynamics of the universe was discovered, people have proposed different extinction scenarios; supernovas (still the most likely, I believe), passing through the galactic plane, passing through spiral spokes, and now passing out of the plane.

    The galactic mergers/replenishment of the spoke dynamics, would surely have been the next big thing, if not our biosphere will probably have been gone by about that time. The next large merger for us will be with Andromeda at about 2 Gyr hence. Fortunately for us the Local Group seems to be late to coalesce to an elliptic galaxy.

    At the same time, we should not complain since Earth happens to inhabit the “sweet spot” that maximizes biosphere lifetime in our solar system.

    [Hear the creationists go “Finetunings! Finetunings! It proves evolution is all wrong, dont’cha know?”]

    Put Earth in the habitable zone of a long-lived red dwarf and the biosphere will have a maximum lifetime of 8.8 Gyr in any case – it would only have given us 2 Gyr more to have a “better” sun. (You would need much larger planets to increase lifetime another 4 Gyr to about 12 Gyr, which seems to be the supremum lifetime in these models.)

    For myself, I wonder what will be up for dinner today. 😛

  3. #3 Torbjörn Larsson, OM
    July 28, 2007

    “8.8 Gyr” “another 4 Gyr”

    Sorry. Make that 9 Gyr and 3 Gyr respectively.

  4. #4 Torbjörn Larsson, OM
    July 28, 2007

    Arnosium Upinarum:

    WHAT “sweet spot”? Our Sun happens to be orbiting

    Obviously the one “that maximizes biosphere lifetime in our solar system”, which should be clear if you read the paper I linked to. Earth happen to lie in the part of our Sun’s habitable zone that maximizes biosphere lifetime, accounting for such effects as thermal balance, internal heat and atmosphere ablation.

    The so-called “Anthropic Principle” (upon which your conclusions are evidently based)

    As I proposed that creationists could latch on to this as a finetuning argument, I was obviously claiming that the result is independent of the papers conclusion.

    Also, it isn’t mine conclusion. You go on in the next comment to attribute the papers result to me or some mysterious “books”, and continue to argue about circumstances which doesn’t affect the referenced model for biosphere lifetimes. (Well, if anything they support them indirectly since the model doesn’t apply to stars with shorter lifetime.)

    In short, you have succeeded in making a long numbers of mistakes in reading and apprehension. I would gladly discuss astronomy or the anthropic principle any day, but circumstances for a rational discussion doesn’t seem to be at hand here.

    Btw, I’m highly amused to be accused of armchair physics by someone who obviously couldn’t care less for given references. You have made my day. 😛

  5. #5 Torbjörn Larsson, OM
    July 28, 2007

    the result is independent of the papers conclusion.

    Oops. Obviously I didn’t mean that – but that the result/the papers conclusion is independent of Earths circumstantial position.

    Note to self – don’t post while juggling three other tasks at the same time.

  6. #6 Torbjörn Larsson, OM
    August 14, 2007

    Sorry for the delay. I wasn’t aware of this reply.

    Arnosium Upinarum:

    I can smell an anthropic argument a mile away

    Obviously not, since I explicitly argued against a common mistake in anthropic arguments. (Creationists use of finetunings.) I often discuss AP, or rather EP, but not here.

    Pick any of them you like.

    I did. You still haven’t seen those references, have you?

    anybody who doesn’t even know how long a red dwarf star lives.

    How anyone can confuse the lifetime of a biosphere with a lifetime of the star beats me, especially since the given references explains this clearly. Is it incompetence in following a simple reference link, incompetence in reading papers or other general incompetence, I wonder?

    Btw, since this thread you had a similar attack arguing against other cosmologies that embeds the concordance cosmology in a larger setting, something you also seems to feel strongly about and make unsupported lashings against. Ironic then that you discuss others need for medication. (But at least you had the sense to cut and run from the following thread.)

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