Reminder: Hangout at 7pm Central tonight

I mentioned this the other day — I’ll be addressing some of your comments on my alienophagy video, and bringing up a few things I wanted to add. Also, of course, if any of you have other questions on just about anything, feel free to fire a few salvos at me.


  1. larpar says

    Since you’re talking about alien life, I have a question about panspermia and Mars. A lot of people think that if we find life on Mars it would help the notion that life was transferred from there to here. But how about the opposite? I think reverse panspermia is just as possible. How could you tell which planet life started on? I don’t know that either scenario happened, but I never hear anyone talk about the reverse.

  2. says

    Mars is smaller and cooled quicker, so probably had conditions favourable for life before Earth did. In addition, it’s a lot easier for rocks to get from Mars to Earth than from Earth to Mars because of Earth’s much greater mass.

    So if life did start in the Solar System in one place and then got transferred to another, it’s far more likely to have started on Mars and got transferred to Earth than the other way around.

    Of course, until we actually find life outside the Earth, this is all wild speculation.

  3. Rob Grigjanis says

    Paul Durrant @2:

    it’s a lot easier for rocks to get from Mars to Earth than from Earth to Mars because of Earth’s much greater mass.

    It’s a lot easier because Earth is closer to the sun than Mars. A lower energy orbit.

  4. jack16 says

    P Z
    Your point about the difficulty of biological contact is on the mark! I’d suggest communication by electronic imagery.

    The only reasonable communication with aliens will be robotic. Concern about motivation is, I think, silly. What could we do? Economically we have nothing that interstellar travelers can’t obtain more easily elsewhere, with one exception. We all desire knowledge! The alien would want to know how we came to exist. As do we in our explorations.

    Consider an alien expedition to our galaxy. (I assume Einstein’s restrictions hold.) The first step. Map the galaxy! Their telescopes could be vast and numerous, constructed by robots using galactic substance.
    Within centuries all life-bearing planets would be located with spectroscopy.