Far distant lands
April 22, 2007 12:46 PM   Subscribe

The first was found just fifteen years ago, after centuries of speculation. As of today, we're up to 227 and counting. Most are just wobbles in data, but we have pictures and exotica too. And we are looking for more (although some think we shouldn't look very hard and others are drawing some surprising conclusions). The science and technology of finding the most fascinating and elusive types demands some of the cleverest engineering, yet you can even have a go for yourself. Previously on Metafilter
posted by Devonian (23 comments total) 1 user marked this as a favorite


posted by Rhomboid at 1:20 PM on April 22, 2007 [2 favorites]

I do love astronomy, but I would ask that you clearly state somewhere what you are talkng about as we're not all as up on extrsolar planets as ya.
posted by JohannStrauss at 1:29 PM on April 22, 2007

The Thing? What is it?

Or, what JohannStrauss said
posted by gottabefunky at 1:40 PM on April 22, 2007

Whatever It is, it doesn't like offsite links.
posted by nebulawindphone at 1:44 PM on April 22, 2007

I prefer posts that tell me what they're about.

Interesting stuff, though.
posted by Anything at 1:55 PM on April 22, 2007

A discussion of the potential for extrasolar life-bearing planets would be incomplete without reference to the Drake Equation. Gene Roddenberry utilized it three years after Drake came up with it, to legitimize the story potential of his TV series idea. Desilu productions bought his spiel, and Star Trek was born. I am such a geek.

Though the future of Star Trek is now being questioned, Drake proved that the idea of there being life-bearing planets is a mathematical probability. Mathematically they do exist. Isaac Asimov determined mathematically in his work Extraterrestrial Civilizations that it's not a question of yes or no. At the most conservative estimates there's a bare minimum of thirty civilizations out there as advanced or more advanced than ourselves, as you are reading these words.

The question isn't a yes or no question. The question is where. Since this galaxy is so big, you have a better chance finding one needle hidden somewhere in all the haystacks that currently exist on this planet. AND the universe is expanding, so we're moving further and further away from other stars, making it even less plausible we'll ever run into one of those thirty civilizations before either they or we exterminate ourselves. So try finding that needle in one of many haystacks as all those haystacks are driving away from you.

This kinda puts a damper on Roddenberry's vision of such a wealth of neato story ideas. Even with warp drive, you'd be hard pressed to find one populated extrasolar planet per week. You have better odds accidently landing on an uncharted island hidden from the real world by unknown forces and containing a bunch of crazy people who like oatmeal.

...what were we talking about?
posted by ZachsMind at 2:19 PM on April 22, 2007 [1 favorite]

Yeah, neat post, but the guessing game's a bit annoying.
posted by dazed_one at 2:19 PM on April 22, 2007

MeFi - it's about stuff, and things like that.
posted by yohko at 2:31 PM on April 22, 2007

The 'surprising conclusions' link is a hoot!
posted by hexatron at 2:42 PM on April 22, 2007

The surprising conclusions link is surprisingly off base. The mean solar mass of other solar systems is currently meaningless, as we can only detect exoplanets that are comparatively enormous. If there are rocky earthlike planets in those systems along with the massive gas giants, we can't or haven't yet found them.

Which makes you wonder why NASA would cancel a project that could help us locate smaller earthlike planets. Unless they weren't really interested in hard science in the first place. Or had to grovel for public funds and stoop to petty human theatre by sending manned missions around the solar system to bring back a few rocks in order to keep the mindless electorate marginally interested...
posted by T.D. Strange at 2:48 PM on April 22, 2007

Ah, sorry about missing any mention of the actual subject! It's a nasty journalistic trick, which I don't like myself - there was a proper mention in a sentence which got removed during an edit when I noticed (at the last minute) that I'd practically re-written a previous post from 2006. I didn't notice that I'd done that, and I apologise. Lesson one: research the Mefi before starting work, not when you hope to have finished. Lesson two: take a break and re-read the final version before posting, as a reader.

I'm still thoroughly shocked that we've gone from zero to 227 in so short a time. It's a true revolution in our understanding of the cosmos, and to be alive when it's just starting is very heaven.
posted by Devonian at 2:54 PM on April 22, 2007

Drake proved that the idea of there being life-bearing planets is a mathematical probability. Mathematically they do exist.

He did no such thing. To paraphrase Babbage, I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a statement.
posted by Aloysius Bear at 2:57 PM on April 22, 2007

Aloysius Bear: "I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a statement."

Oh puh-puh-puh-puh-puh-puh-puh-puh-pleeeze, Eddie?!
posted by ZachsMind at 3:01 PM on April 22, 2007

Okay I'll try to be more serious here, rather than quote from children's movies.

I ask you please to read Asimov's argument regarding the Drake Equation located in Extraterrestrial Civilizations before you dismiss my determinant. It's very compelling work. He rambles on more than I do, but that's why I love the ripe old bastard.

The odds that there are no other civilizations aside from ourselves is worse than the odds that there are, meaning it's a mathematical probability that they do exist. It's also a mathematical probability that they don't, but the odds that they do exist is less outrageous than the odds that they don't. I don't know the exact numbers cuz as Asimov points out, you have to make conservative estimates to get a general idea. At the most conservative of estimates, it's still more probable that they do exist than they don't.

Simultaneously, it's a mathematical probability that we will never find them and they will never find us. Meaning that stories of flying saucers and little green men flying about Roswell New Mexico back in the 1940s are even more remotely implausible than we thought, but still minutely, finitely probable.

Now if you can bring me a cat, a box, and a radioactive isotope, I'll show you my next trick!
posted by ZachsMind at 3:11 PM on April 22, 2007

Aloysius Bear - thanks, I think I know what I'm going to have engraved on the back of my next iPod.
posted by b1tr0t at 3:13 PM on April 22, 2007

damn, too long
posted by b1tr0t at 3:18 PM on April 22, 2007

The mean solar mass of other solar systems is currently meaningless, as we can only detect exoplanets that are comparatively enormous.

And also, since we've been doing this only a relatively short period of time, planets that have a relatively short orbital period.

The usual way we now detect these extra-solar planets requires gathering data over several orbits of the planet.

So figure it out--how long to we have to monitor a particular star to detect whether or not it has a planet with an orbit similar to, say, Saturn (orbital period about 30 years) or Uranus (orbital period about 84 years)?

Based on the amazing abundance of short-period planets, longer-period planets are probably also very abundant.

Based on the amazing abundance of large planets, there are also probably plenty of smaller planets.

Based on all that, every type of "solar system" that physically can exist, probably does exist in reasonable abundance.

Of course all of that, aside from the 224 planets we have actually detected, is just a guess. But the ideas we have about how stars and solar systems form, plus the fact that there is one particular type of planet we can detect (large with a short-period orbit) and we have found that particular type of planet in really amazing abundance, suggest pretty strongly that the other types of planets and various types of solar systems are all there, waiting to be discovered.
posted by flug at 3:31 PM on April 22, 2007

ZachsMind - I appreciate your enthusiasm. I'd like it if it were true too. And I appreciate your caution regarding distance and finding other civilizations and how unlikley that is. But still I think you put your statements a bit too strongly.

It is not a mathematical probability that other civilizations as advanced as ours exist. I find Drake's equation very stimulating too...but as one astronomer put it:

"Unfortunately, of the seven factors that appear on the right side of the Drake Equation, only one (R*) can be estimated at present with any degree of confidence."

You can't say it's mathematically probable when there is so much disagreement on the range for the other factors. Speculation doesn't make for mathematical probablity.

In time we will probably have a very good estimate for at least the first 3 factors, but the last 4 just aren't likely to ever be answered definitively, at least not in our lifetimes, and probably not in many lifetimes.

Just taking the one factor (Fi - the fraction of planets with life where intelligent life evolves) and you have many orders of magnitude disagreements. From scientists who believe it is close to zero to those who believe it is one or very close to one. If just that one factor is close to zero then it is mathematically improbable that other intelligent civilizations exist in our galaxy.

Sorry, I have some sort of inherent aversion to what a good friend of mine calls "soft thinking". And this topic always seems to be a source of it from otherwise very intelligent folks. "But there's soooo many stars and planets out there - there HAS to be other intelligent life!" No, no there does not have to be.

If there are X stars and life as we know it is as rare as .1X then odds are we're alone here. You can buy 100,000 lottery tickets (which is ALOT of tickets) and you're still unlikely to win.

The challenge with Drake's equation is to recognize that we really don't know what X and .1X are - we probably will get X down to a good tight range. But the way Drake phrased the other 4 factors and the incredibly small sample size we are dealing with (only 1 example of "intelligent life") mean that we're not likely to ever know what the rarity of life like us is.
posted by django_z at 4:49 PM on April 22, 2007

I agree with django_z. Inasmuch as it fosters lazy thinking, Drake's equation should probably be retired and forgotten, just like Moore's law and other qualitative and inexact things which are inaproppriately using the precise language of mathematics.

As has been said many, many times in these threads, the fact that we have one and only one example of a planet with Life on it makes any statements about extra-terrestrial life pure speculation.
posted by vacapinta at 5:24 PM on April 22, 2007

Not _pure_ speculation, otherwise we couldn't even start to design experiments to detect extra-terrestrial life. It seems to me to be reasonable to say that there may be further information in spectrographic analysis of the atmospheres of Earth-like extrasolar planets, and that we have a good chance of doing that experiment.

Drake's Equation is a thought experiment. As such, it's been very useful in helping people think about the issues and fosters a common language for the debate. As mathematics, no, it's not a 'real' equation that produces a 'real' answer, and there is always a danger - as with any metaphor - that people will focus on the details of the example to the detriment of that which it illustrates.

(Moore's Law is a different kettle of squid. First, it really does seem to match the figures -- if anything, these days, it's too conservative -- and it also provides a constant goal for those working in the field. Granted, it's not a law, it's an observation, but it has defined an industry's own sense of what it should do.)
posted by Devonian at 6:21 AM on April 23, 2007

Related to the Drake's equation business is the Fermi Paradox, which is that, assuming a high likely hood of extraterrestrial life, why haven't we found any yet?

It only takes one species going a little bit further than where we are now, at any point in our galaxy's history to produce megascale engineering which we would be able to detect today, even if that species had since died out. If just one civilization anywhere near us had ever sustained a two or higher on theKardashev scale, we should be able to find the remnants.

I'm an optimist, but it's definietly a problem.
posted by Arturus at 8:52 AM on April 23, 2007

Zach: I wouldn't say the Drake Equation "proves" anything. It's a philosophical construct, not a mathematical one.
posted by absalom at 1:52 PM on April 23, 2007

On Preview: What other people said.

Oh, and speaking of philosophical and not scientific: the Kardashev scale. Interesting conceptually and for David Brin novels, but meaningless in any sort of truly predictive discussion.

As to the Fermi Paradox, I think it brings with it too many assumptions. The universe is *old* and we are not. Why should tons and tons of civilizations come and gone in the past that we'd never know about. I mean, it seems to me that Fermi is nakedly progressivieist here in assuming that once you hit intelligence, it's a linear upward progression. Who says these races didn't all extinguish themselves. I mean, I don't like *our* chances. Why should other evolved races not also face the same impediments to space travel and exploration that we do?

And, for that matter, space is *big*. This progressivist attitude also seems to assume that, given enough time, the impossible enormity of the cosmos is just a speed bump, although I think there is absolutely nothing in current physics canon to justify that assumption. It seems to me that there are *plenty* of answers to the so-called "paradox."

I mean, come on, at some point over the last 3.5 billion years, this planet has been livable (as we define it.) Of the past 30,000-2.5 million years, depending on how you reckon it, there has been "intelligent" life here. The past 100 of those years might somehow be detected by some other civilization.... eventually. If we go another 200 years as a civilization, I'll be surprised, but let's even say 1000, that gives us a window of something like .0000000314 percent.

Anyway, in short (too late), why should the problems that keep us silent conspire to do the same for them? You know, plus what everyone else said. Soft thinking, indeed.
posted by absalom at 2:12 PM on April 23, 2007

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