My Actual Homepage - Go here for more info.


I plan to put a graphical banner here eventually...

Amazon Contextual Product Ads

06 March 2011

Fermi's Paradox and (somewhat) Recent Kepler Results

Back at the start of February, Kepler released 1200 candidates for planets around other stars.  This is a fantastic bit of data, and I am looking forward to getting more concrete results from this.  Of course, with the generally scientifically illiterate public, this undoubtedly has caused a lot of confusion amongst the masses.  While discussing this with some folks at work, someone brought up the Fermi's Paradox canard.  While this may seem to make sense at a visceral level, it's pure bunk.  There are just so many reasons as to why we haven't been able to look a lot of places, or why anyone else hasn't checked us out yet.

Let me try to list a few of them here for your benefit:
  • Space is frikkin huge!!!!!!!!!!!!!!! 
    "Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space," - The Hitchhiker's Guide to the Galaxy
    Any scale you can think of is dwarfed by the distances involved.  This should be the first and only step required to dismiss the Fermi's Paradox canard.  Yet, for some reason, people refuse to understand just how amazingly big the universe is, so they discount this.  So maybe I need to talk about some additional reasons why it's a canard.
  • The inverse square law!  One of the problems with omni-directional signals is that they decrease with the inverse square law (well, all signals do, but a focused beam has much more "oomph" to start with, so it will be detectable further).  This web page describes it best I think: http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html  There is a table about two thirds down the page that captures this:

    -------------+--------------+-----------+--------+--------+-----------+
    Source       | Frequency    | Bandwidth | Tsys   | EIRP   | Detection |
                 | Range        |    (Br)   |(Kelvin)|        | Range (R) |
    -------------+--------------+-----------+--------+--------+-----------+
    AM Radio     | 530-1605 kHz |  10   kHz | 68E6   | 100 KW |  0.007 AU |
    -------------+--------------+-----------+--------+--------+-----------+
    FM Radio     |  88-108  MHz | 150   kHz |  430   |   5 MW |    5.4 AU |
    -------------+--------------+-----------+--------+--------+-----------+
    UHF TV       | 470-806  MHz |   6   MHz |  50  ? |   5 MW |    2.5 AU |
    Picture      |              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    UHF TV       | 470-806  MHz |   0.1  Hz |  50  ? |   5 MW |    0.3 LY |
    Carrier      |              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    WSR-88D      |   2.8    GHz |  0.63 MHz |  40    |  32 GW |   0.01 LY |
    Weather Radar|              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    Arecibo      |   2.380  GHz |  0.1   Hz |  40    |  22 TW |    720 LY |
    S-Band (CW)  |              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    Arecibo      |   2.380  GHz |  0.1   Hz |  40    |   1 TW |    150 LY |
    S-Band (CW)  |              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    Arecibo      |   2.380  GHz |  0.1   Hz |  40    |   1 GW |      5 LY |
    S-Band (CW)  |              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    Pioneer 10   |   2.295  GHz |  1.0   Hz |  40    | 1.6 kW |    120 AU |
    Carrier      |              |           |        |        |           |
    -------------+--------------+-----------+--------+--------+-----------+
    The main thing to take away from this table is that our own civilization is barely detectable outside the orbit of Neptune!  That said, I still run SETI@Home on the off chance that we find something.  I am ever the optimist.
  • Why do people always assume that a totally alien species will be motivated by the same things we would be?  Even if they are intelligent,who is to say that we would even recognize it.  Heck, we aren't so sure about intelligence of other species on this planet.
  • We have hardly looked anywhere.  Generally, we have only looked seriously for anything in a 300 light year bubble around our planet.  See point 1, space is huge.  Our galaxy is 100,000 light years across, and just looking in a tiny section one would expect some results?
  • Our technology is primitive!  Yeah, we may be the most technically advanced species on the planet, but we have barely left low earth orbit.  Sure, we've sent some probes around, but as a species, we've not ventured very far at all.
  • A lot of people get all on about the "rare earth" hypothesis.  First of all, this is total bunk.  The only reason we needed all the conditions for this earth to evolve here is because we evolved here, and not elsewhere.  It's like saying that a puddle is made for the hole in which it sits...
  • Confirmation bias:  The majority of planets (not withstanding the tentative Kepler results) we have found are gas giants that orbit close to their stars.  This may have more to do with the fact that those were the only ones we were CAPABLE of finding...  That point is all too often lost on people.
  • Exactly how many detectable signals have WE sent out?  As I mentioned before, a lot of people think that aliens will have the same motivations and way of doing things that we do, yet they don't understand why we haven't received any radio signals of note.  Well, if they send out signals like we do, then that's going to be a low probability find!  As a species that has had radio technology for several decades, we have only sent out 19 messages.  That's hardly anything! 
  • Basic Physics:  Did I mention that space is huge?  To travel, send signals, or even probes over those immense distances requires much better than what we are doing or realistically can do right now.
So, if someone asks, "Where are they?" tell them that they are probably stuck on their planet, just like we are.  We have only scooped one cup of water out of the pacific without finding any fish, so it is much too early to declare that the entire ocean is devoid of all fish.

    1 comment:

    Anonymous said...

    One of the most brilliant discussions I have read recently on the subject. Not that Drakes Equation is particularly useful, but if we stick with using it, the number of inhabitable worlds appears to soon increase magnificently.