The Drake Equation again

-
I was walking in to work today and as I did I was listening to a nice podcast on the Drake Equation.  The Drake Equation is an estimate of the number of civilizations in the galaxy based on things like how many planets there are, how many develop life, etc.  I learned a lot in the Podcast but it reminded me of a post I'd been meaning to make about why I think the origin of life probably wasn't the hard part in creating us.  Also, I promise this post on the Drake Equation is more pleasant than the last one.

A graph:

Dates taken from Wikipedia's timeline of life and timeline of the future.

It was just a pretty short amount of time, geologically, from when the Earth cooled down enough for oceans to start forming until we have proof of the first life - just 120 million years.  And that's probably a conservative estimate.  But from there it took three quarters of a billion years for photosynthesis to arise.  Then one and a half billion until one bacteria swallowed another in such a way as to turn it into a mitochondria and then become a big complex eukaryotic cell.  Then another billion before we had real multicellular life. 

So just looking at the timelines involved it seems like the origin of life wasn't the hard part.  If you're interested Nick Lane has some excellent books about the biochemical difficulties of these steps and why life might have been the easy part but for the Drake Equation the important part is that becoming complex took a long time.

And it's also important that life only had so much time to become complex because in just another billion years the brightening Sun will heat up our planet enough to evaporate the oceans and then there's not much chance of intelligent life evolving.  And it's very lucky that photosynthesis showed up so early.  If the Earth's carbon dioxide atmosphere hadn't been broken down into oxygen then Earth might have had a runaway greenhouse effect by now.  And without oxygen in the atmosphere to form ozone we might have lost the hydrogen atoms we need for water to the Sun's solar wind.

Looking at that timeline makes me feel optimistic that the reason there don't seem to be any aliens in the galaxy is that evolving intelligent life is hard, rather than that intelligent life tends to meet a grisly end.

Comments

  1. LiaMarch 7, 2018 at 8:12 PM

    Nice article! What do you think about Bill Gates, Elon Musk, and some other people's concern about how dangerous AI could be to humanity?

    ReplyDelete
  2. Andrew CloughMarch 7, 2018 at 8:15 PM

    I take them seriously but not quite enough so to be donating to MIRI or other organizations looking at the problem as opposed to Malaria eradication.

    ReplyDelete
  3. LiaMarch 7, 2018 at 10:23 PM

    I did not know about this institute. Very interesting. Thanks for sharing!

    ReplyDelete
  4. Richard NgoJune 1, 2018 at 4:29 PM

    Great post, and I'm a fan of the rest of the blog as well. One suggestion - I'd have had a much easier time navigating through it if you'd had either a "best of" list, or else a better-formatted way to scroll through the entire archive.

    ReplyDelete
  5. jqbJune 5, 2018 at 12:30 AM

    False dichotomy. Evolving life is hard, and grisly ends are likely.

    ReplyDelete

Post a Comment

Popular posts from this blog

Book Review: Power, Sex, Suicide

-
  Introducing the Mitochondria “The mitochondria is the powerhouse of the cell” - Variously attributed Everybody learns something about Mitochondria in grade school.  That they are an organelle inside your cells.  That they let your body break down sugar and create ATP using oxygen in a way that’s far more efficient than fermentation without oxygen.  That’s clearly an important role, when we’re drowning, say, and can’t get the oxygen needed for aerobic respiration we die.  However, they’re a lot more than that too.  Mitochondria used to have independent bacterial lives charting their own fates.  That their existence came to be so enmeshed with their hosts is arguably the most unlikely but important event in the history of life on Earth and has some implications. Pump and Dump Aerobic Respiration Essentially all life lives by extracting energy from a difference in the concentration of hydrogen across a lipid membrane.  Let’s say you’re a mitoch...
Read more

Sometimes you need a new word

-
Lets say I'm telling a story about some hiker heading up into the mountains.  I mention that when passing under a cliff a pebble came loose and landed on him.  That might sting but it wouldn't occur to you to ask if he died.  Lets say that instead I mention that a boulder had landed on him.  Then you'd expect him to be quite dead. That's the nice thing about these old English words that've been around a while and encode distinctions that make sense in our everyday lives.  The difference between the pebble and the boulder is just a matter of degree but it's one where the quantitative difference is big enough to become qualitative.  If we just had one word whoever I was telling the story to would have to ask questions and because we run into rocks so often I'd know when I'd have to use an adjective. When you're talking about scientific things, though, you don't often have this choice of words.  Energy is energy and you're expected to use a ...
Read more

Seveneves and the Roche limit

-
For an author it's important to get things that the reader might find hard to swallow out there and dealt with as soon as possible.  I didn't really enjoy Neal Stephenson's last book, REAMDE , past the halfway point because too many improbably occurrences had piled up and my suspension of disbelief didn't recover.  By contrast his newest novel, Seveneves , seems to be doing an excellent job of getting the improbable stuff dealt with quickly and I've been enjoying the book without any hangups.  I've only gotten through chapter 7, acknowledged, but I've got a feeling I'll continue to enjoy this one. But of course the second improbable of the two things gives me a chance to talk about some physics I find interesting so I'm going to dissect what I think Stephenson gets wrong.  Not because I think the author is a bad person or wrote a bad book but just because I think the physics is nifty and reading this prompted me to share it. The basic setup of th...
Read more