December 11, 2007

Life Elsewhere...a No-Brainer?


This image might look like a painting or a digital graphic, but it's not...

So... is the existence of life common in the Universe? Can an assertion that life probably does exist elsewhere be construed as a valid scientific theory, or can it be viewed as an assumption only?

The answers seem to be: probably; and such an assertion might be viewed as a valid, but borderline scientific theory- based on probability, which in turn may be based on observational evidence.

Anyone reading this post knows that our Earth is a mere speck in the vastness of the known universe. The Sun is a very average yellow dwarf star. According to the latest estimates, there are between 200 and 400 billion stars in the galaxy we reside in (the exact number will most likely never be known because of the gargantuan amount of gas and dust obscuring our view). How many of these stars have planetary companions? It's safe to say that a large percentage of them do.

How many galaxies are in the known universe? Recent estimates are as high as 500 billion. The Hubble Deep-Sky camera photographed a small area of the sky a few years back- an area 1/150th the apparent size of the moon. 3,000 galaxies were counted in that small area alone!

As far as we know, the universe elsewhere is composed of the same elements that we, our Earth, our sun, and our galaxy are composed of. The physical laws of nature, as we know them, seem to apply everywhere in the observable universe, as far as we have seen.

It happened here... why not elsewhere? It doesn't even have to be carbon-based... but we'll save that for a future post.

And what about the probability that some "supreme being" created the whole universe just for us? One can't help but be purely subjective on this, but I say... ZERO.

Mark T.

8 comments:

MarkT said...

I should mention that the amazing deep-sky photo is courtesy of

http://hubblesite.org/

Michael said...

I have read that there are theories that there are bacteria alive in the clouds of Venus. And I have heard something about bacteria being found on rocks that came from Mars. Do the math. It is more improbable that there is no other life than there is a god.

Michael

MarkT said...

Jupiter's moon Europa,and Saturn's moon Enceladus may give us some clues, eventually. On both worlds, scientists are quite sure about the presence of H2O.

So is life that amazing, or is it a fairly common result of the interlocking of the patterns of nature? One day we will know.

Brock said...

http://xkcd.com/384/
(read the alt-text as well)

Just some nitpicks...

"Can an assertion that life probably does exist elsewhere be construed as a valid scientific theory [?] ... Probably."

-- No, it's a hypothesis. Scientific theories (as contrasted with "popular" theories) require a pretty heavy burden of evidence. We'll know when we have better tools and methods. Right now our tools are very, very crude.

"How many of these stars have planetary companions? It's safe to say that a large percentage of them do."

-- We don't know that yet. It's perfectly valid in science to admit when something is speculative, instead of asserting it as fact. We've only actually found a few dozen extrasolar planets so far, because they're hard to detect.

"And what about the probability that some "supreme being" created the whole universe just for us?"

-- There's a finite probability for a LOT of weird stuff. Though incredibly small, 1 chance in 10^20 is still not zero (though you might safely bet your life against it). I'm not disagreeing with the perspective, just the semantics.

I'm thoroughly excited about future exploration of Europa and Titan, because of the H2O of the former (as you mention) and atmosphere of the latter.

MarkT said...

I appreciate the nitpicks, Brock. Those will help me to get better at this, eventually... semantics can get in the way sometimes, but in instances such as this they are important.

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