Polling astronomers or observing the universe?

[Ann]

Last Thursday I was able, for once, to attend an astronomy meeting hosted by the astronomy club that I'm loosely attached to. (I'm so rarely able to attend their meetings, so I keep forgetting to pay my membership fee.)

Anyway. Our chairman, whose name I will not mention since I'm going to be a bit critical of him, has written a book, and this meeting was primarily about him talking about that book of his. He has written about life in space, and the way I understand it (I haven't bought or read his book) what it all boils down to is an impassioned plea for all of us to believe in life in space.

I should add, too, that our chairman wasn't primarily talking about microbial life on other planets. He showed us several illustrations of vaguely humanoid and obviously intelligent aliens, not as blank-faced as this guy, but you get the idea.

Yes, well, there is no real shortage of such books, I think. Although it could be that our chairman's book is the first ambitious one on the subject in Swedish.

Of course it's fine to write a book where you plead with your readers to believe in life in space. But our chairman is not an astrobiologist and not a real expert on the topic he has written about. On several occasions during his speech to us, he told us that he had been forced to consult very many experts and to learn very many new things about life and astrobiology before he could write his book.

So one reason why I didn't buy his book is that I prefer to get my information from people who are experts in their fields and are very respected by their peers.

Anyway. During the discussion that followed after our chairman's speech, he himself turned to the only active professional astronomer who was present in the auditorium, professor Dainis Dravins, and demanded that Dravins expound on the attitudes of other professional astronomers to the concept of life on other planets. Do other astronomers believe there is life in space? Do they poll one another to find out what most of them believe?

Dainis Dravins answered: Well, no, we don't really poll one another. We are too busy making observations and working out theories and coming up with new ways to search for signs of life in space to have time for polls.

Ann

P.S. And this picture has nothing to do with the content of my post, but I couldn't resist.

[Beyond]

Yes, resistance was futile.

[neufer]

I should add, too, that our chairman wasn't primarily talking about microbial life on other planets. He showed us several illustrations of vaguely humanoid and obviously intelligent aliens, not as blank-faced as this guy, but you get the idea.

Yes, well, there is no real shortage of such books, I think. Although it could be that our chairman's book is the first ambitious one on the subject in Swedish.

Of course it's fine to write a book where you plead with your readers to believe in life in space. But our chairman is not an astrobiologist and not a real expert on the topic he has written about. On several occasions during his speech to us, he told us that he had been forced to consult very many experts and to learn very many new things about life and astrobiology before he could write his book.

So one reason why I didn't buy his book is that I prefer to get my information from people who are experts in their fields and are very respected by their peers.

Which is entirely your option (as is paying your dues and attending his lecture).

"Plead with [his] readers?" "Been forced to consult?" Give me a break

You expound quite a bit here at the Asterisk* about astronomy, Ann, and no one has yet demanded to see your official academic credentials to do so. Do you think that we should? (And if not why not?)

[geckzilla]

Oftentimes people comment over at the Facebook APOD page with things such as, "Who could possibly believe we are alone in the Universe?" My only thoughts on that matter is that there is simply no evidence yet. The possibility of Earth being the sole location of life of any kind remains on the table no matter how you calculate the probability. I do, of course, think it is a pretty low chance but no one, no matter what his credentials are, can say with certainty that life exists anywhere else until there is plenty of evidence to back up such assertions.

[neufer]

Oftentimes people comment over at the Facebook APOD page with things such as, "Who could possibly believe we are alone in the Universe?" My only thoughts on that matter is that there is simply no evidence yet. The possibility of Earth being the sole location of life of any kind remains on the table no matter how you calculate the probability. I do, of course, think it is a pretty low chance but no one, no matter what his credentials are, can say with certainty that life exists anywhere else until there is plenty of evidence to back up such assertions.

Statistics suggest the probability of other life in the Milky Way is extremely high.

Statistics suggest the probability of other intelligent life in the Universe is extremely high.

[Chris Peterson]

Statistics suggest the probability of other life in the Milky Way is extremely high.

Statistics suggest the probability of other intelligent life in the Universe is extremely high.

Weren't you recently railing against statistics?

I'd say that the evidence based on our observations here on Earth, our observations of other stellar systems, and our theories about life suggest a very high probability of life elsewhere in the Universe. It's a lot harder to rationally assess what percentage of that life might be intelligent, however, or even particularly complex.

While I do agree with your statistical assertions, simply because the Universe is so large, the more interesting question comes down to absolute numbers, and we're far from being able to assign values with any confidence.

[neufer]

Statistics suggest the probability of other life in the Milky Way is extremely high.

Statistics suggest the probability of other intelligent life in the Universe is extremely high.

Weren't you recently railing against statistics?

The hallmark of my posts is that they are self referential.
(I thought that was general knowledge.)

I'd say that the evidence based on our observations here on Earth, our observations of other stellar systems, and our theories about life suggest a very high probability of life elsewhere in the Universe. It's a lot harder to rationally assess what percentage of that life might be intelligent, however, or even particularly complex.

While I do agree with your statistical assertions, simply because the Universe is so large, the more interesting question comes down to absolute numbers, and we're far from being able to assign values with any confidence.

Which is why I didn't assign values.

(I'm also pretty sure there is life in Judy's Jelly jar;
the only question is whether or not it is intelligent life.)

[Ann]

neufer wrote:

You expound quite a bit here at the Asterisk* about astronomy, Ann, and no one has yet demanded to see your official academic credentials to do so. Do you think that we should? (And if not why not?)

I haven't written a book.

Ann

[neufer]

neufer wrote:

You expound quite a bit here at the Asterisk* about astronomy, Ann, and no one has yet demanded to see your official academic credentials to do so. Do you think that we should? (And if not why not?)

I haven't written a book.

You've more than written a book.

[rstevenson]

Now there's a thought! Astronomy By Colour, by Ann.

I'd buy it (in eBook format, of course.)

Rob

[Ann]

Click to view full size image

neufer wrote:

Statistics suggest the probability of other life in the Milky Way is extremely high.

Statistics suggest the probability of other intelligent life in the Universe is extremely high.

I can't deny the probability that there might well be intelligent life in one or more of the galaxies seen in this Hubble Deep Field (or in the galaxies that the HDF galaxies have since developed into).

But how do we measure this probability?

Ann

[neufer]

I can't deny the probability that there might well be intelligent life in one or more of the galaxies seen in this Hubble Deep Field (or in the galaxies that the HDF galaxies have since developed into).

But how do we measure this probability?

[b][size=150][color=#0000FF]'Comet' Encke phones home.[/color][/size] Credit: Michael Jaeger[/b]

---

Sagan's number: the number of stars in the observable universe, currently estimated to be 7·10²².

Since we know that at least one star produced an intelligent life-form for at least 13.7 thousand years (of the universe's 13.7 billion years existence) then a reasonably conservative estimate might be:

265,000 intelligent life-form stars
= sqrt(7·10²²) x [13.7 thousand/13.7 billion]

But I suspect it is much higher than that.

[Beyond]

Looks like a little bit of star wars going on in that picture.