Astrobiology III: Why Earth?

17 CellBioGuy 04 October 2016 09:59PM

After many tribulations, my astrobiology bloggery is back up and running using Wordpress rather than Blogger because Blogger is completely unusable these days.  I've taken the opportunity of the move to make better graphs for my old posts. 

"The Solar System: Why Earth?"

https://thegreatatuin.wordpress.com/2016/10/03/the-solar-system-why-earth/

Here, I try to look at our own solar system and what the presence of only ONE known biosphere, here on Earth, tells us about life and perhaps more importantly what it does not.  In particular, I explore what aspects of Earth make it special and I make the distinction between a big biosphere here on Earth that has utterly rebuilt the geochemistry and a smaller biosphere living off smaller amounts of energy that we probably would never notice elsewhere in our own solar system given the evidence at hand. 

Commentary appreciated.

 

 

Previous works:

Space and Time, Part I

https://thegreatatuin.wordpress.com/2016/09/25/space-and-time-part-i

Space and Time, Part II

https://thegreatatuin.wordpress.com/2016/09/25/space-and-time-part-ii

Astrobiology, Astronomy, and the Fermi Paradox II: Space & Time Revisited

23 CellBioGuy 10 March 2016 05:19AM

After a 6+ month hiatus driven by grad school and personal projects, I am finally able to continue my sequence on astrobiology.  I was flabbergasted by the positive response my last post got, and despite my status as a biologist with a hobby rather than an astronomer I decided to take a more rigorously mathematical approach to figuring out our biosphere's position in space and time rather than talking in generalizations and impressions.

Post is here:  http://thegreatatuin.blogspot.com/2016/03/space-and-time-revisited.html.  Seeing as this post is an elaboration on the last one, I am posting a link rather than reproducing the text.

To summarize, I found some actual rigorous observational fits to the star formation rate in the universe over time and projected them into the future.  These fits show the Sun as forming after 79% of all stars that will ever exist, and that 90% of all stars that will ever exist already exist.  This makes sense in the light of recent work on 'galaxy quenching' - a process by which galaxies more or less completely shut off star formation through a number of processes - indicating that the majority of gas in the universe probably won't form stars if trends that have held for most of the history of the universe continue to hold.  It relies heavily on analysis I began in comments on this site a few months ago.

I then lift two distinct metallicity normalizations from a paper that was making the rounds here a while back ("On The History and Future of Cosmic Planet Formation"), in an attempt to deal with the fact that that is a measurement of STAR formation, not terrestrial-planet-with-a-biosphere formation.  Depending on which metallicity normalization you use (and how willing you are to take a couple naive assumptions I make in order to slot the math that is too complicated for me to comment on on top of my star formation numbers) the Earth shows up as forming after either 72% or 51% of all terrestrial planets.

These numbers are remarkable in how boring they are.  We find ourselves in an utterly typical position in planet-order, even if I am wrong by quite a bit.  We are not early.  Of interest to many here, explanations of the so called Fermi paradox must go elsewhere, into the genesis of intelligent systems being exceedingly rare or the genesis of intelligent systems not implying interstellar spread.

Now that I seem to have a life again, I will be getting back to my original plan next, talking about our own solar system.

Astronomy, Astrobiology, & The Fermi Paradox I: Introductions, and Space & Time

42 CellBioGuy 26 July 2015 07:38AM

This is the first in a series of posts I am putting together on a personal blog I just started two days ago as a collection of my musings on astrobiology ("The Great A'Tuin" - sorry, I couldn't help it), and will be reposting here.  Much has been written here about the Fermi paradox and the 'great filter'.   It seems to me that going back to a somewhat more basic level of astronomy and astrobiology is extremely informative to these questions, and so this is what I will be doing.  The bloggery is intended for a slightly more general audience than this site (hence much of the content of the introduction) but I think it will be of interest.  Many of the points I will be making are ones I have touched on in previous comments here, but hope to explore in more detail.

This post references my first two posts - an introduction, and a discussion of our apparent position in space and time in the universe.  The blog posts may be found at:

http://thegreatatuin.blogspot.com/2015/07/whats-all-this-about.html

http://thegreatatuin.blogspot.com/2015/07/space-and-time.htm

Irrationality Game III

11 CellBioGuy 12 March 2014 01:51PM

The 'Irrationality Game' posts in discussion came before my time here, but I had a very good time reading the bits written in the comments section.  I also had a number of thoughts I would've liked to post and get feedback on, but I knew that being buried in such old threads not much would come of it.  So I asked around and feedback from people has suggested that they would be open to a reboot!

I hereby again quote the original rules:

Please read the post before voting on the comments, as this is a game where voting works differently.

Warning: the comments section of this post will look odd. The most reasonable comments will have lots of negative karma. Do not be alarmed, it's all part of the plan. In order to participate in this game you should disable any viewing threshold for negatively voted comments.

Here's an irrationalist game meant to quickly collect a pool of controversial ideas for people to debate and assess. It kinda relies on people being honest and not being nitpickers, but it might be fun.

Write a comment reply to this post describing a belief you think has a reasonable chance of being true relative to the the beliefs of other Less Wrong folk. Jot down a proposition and a rough probability estimate or qualitative description, like 'fairly confident'.

Example (not my true belief): "The U.S. government was directly responsible for financing the September 11th terrorist attacks. Very confident. (~95%)."

If you post a belief, you have to vote on the beliefs of all other comments. Voting works like this: if you basically agree with the comment, vote the comment down. If you basically disagree with the comment, vote the comment up. What 'basically' means here is intuitive; instead of using a precise mathy scoring system, just make a guess. In my view, if their stated probability is 99.9% and your degree of belief is 90%, that merits an upvote: it's a pretty big difference of opinion. If they're at 99.9% and you're at 99.5%, it could go either way. If you're genuinely unsure whether or not you basically agree with them, you can pass on voting (but try not to). Vote up if you think they are either overconfident or underconfident in their belief: any disagreement is valid disagreement.

That's the spirit of the game, but some more qualifications and rules follow.

If the proposition in a comment isn't incredibly precise, use your best interpretation. If you really have to pick nits for whatever reason, say so in a comment reply.

The more upvotes you get, the more irrational Less Wrong perceives your belief to be. Which means that if you have a large amount of Less Wrong karma and can still get lots of upvotes on your crazy beliefs then you will get lots of smart people to take your weird ideas a little more seriously.

Some poor soul is going to come along and post "I believe in God". Don't pick nits and say "Well in a a Tegmark multiverse there is definitely a universe exactly like ours where some sort of god rules over us..." and downvote it. That's cheating. You better upvote the guy. For just this post, get over your desire to upvote rationality. For this game, we reward perceived irrationality.

Try to be precise in your propositions. Saying "I believe in God. 99% sure." isn't informative because we don't quite know which God you're talking about. A deist god? The Christian God? Jewish?

Y'all know this already, but just a reminder: preferences ain't beliefs. Downvote preferences disguised as beliefs. Beliefs that include the word "should" are are almost always imprecise: avoid them.

That means our local theists are probably gonna get a lot of upvotes. Can you beat them with your confident but perceived-by-LW-as-irrational beliefs? It's a challenge!

Additional rules:

  • Generally, no repeating an altered version of a proposition already in the comments unless it's different in an interesting and important way. Use your judgement.
  • If you have comments about the game, please reply to my comment below about meta discussion, not to the post itself. Only propositions to be judged for the game should be direct comments to this post. 
  • Don't post propositions as comment replies to other comments. That'll make it disorganized.
  • You have to actually think your degree of belief is rational.  You should already have taken the fact that most people would disagree with you into account and updated on that information. That means that  any proposition you make is a proposition that you think you are personally more rational about than the Less Wrong average.  This could be good or bad. Lots of upvotes means lots of people disagree with you. That's generally bad. Lots of downvotes means you're probably right. That's good, but this is a game where perceived irrationality wins you karma. The game is only fun if you're trying to be completely honest in your stated beliefs. Don't post something crazy and expect to get karma. Don't exaggerate your beliefs. Play fair.
  • Debate and discussion is great, but keep it civil.  Linking to the Sequences is barely civil -- summarize arguments from specific LW posts and maybe link, but don't tell someone to go read something. If someone says they believe in God with 100% probability and you don't want to take the time to give a brief but substantive counterargument, don't comment at all. We're inviting people to share beliefs we think are irrational; don't be mean about their responses.
  • No propositions that people are unlikely to have an opinion about, like "Yesterday I wore black socks. ~80%" or "Antipope Christopher would have been a good leader in his latter days had he not been dethroned by Pope Sergius III. ~30%." The goal is to be controversial and interesting.
  • Multiple propositions are fine, so long as they're moderately interesting.
  • You are encouraged to reply to comments with your own probability estimates, but  comment voting works normally for comment replies to other comments.  That is, upvote for good discussion, not agreement or disagreement.
  • In general, just keep within the spirit of the game: we're celebrating LW-contrarian beliefs for a change!

I would suggest placing *related* propositions in the same comment, but wildly different ones might deserve separate comments for keeping threads separate.

Make sure you put "Irrationality Game" as the first two words of a post containing a proposition to be voted upon in the game's format.

Here we go!

EDIT:  It was pointed out in the meta-thread below that this could be done with polls rather than karma so as to discourage playing-to-win and getting around the hiding of downvoted comments.  If anyone resurrects this game in the future, please do so under that system  If you wish to test a poll format in this thread feel free to do so, but continue voting as normal for those that are not in poll format.