Is there life elsewhere in the universe? 90 second lecture (6/11)

Uploaded by OUlearn on 17.12.2008

Is there life elsewhere in the universe?
Well, astronomers tend to cluster into two groups.
There are the very strong yeses and the very strong noes,
but really, there's not a lot of evidence to go on.
So, you have a number of planets in the universe,
a big number times the probability of forming life,
which is a very small number,
and you don't know either of those numbers terribly well.
So, there's not a lot of evidence to go on.
Meanwhile, there's a lot of discussion as to what life really is.
So, for example, are viruses alive?
That's a difficult question to answer.
But, there's a completely different way of answering this question.
Not only is there no life elsewhere in the universe,
there's no life on earth,
and this is because there is no such thing as life.
There is no magic spark or quintessence,
that separates living things from non-living things -
there is just complex organic chemistry and that's all.
And to me, that's a very appealing simplification.
Now, philosophers have a fallacy called the blue/green argument,
so, you imagine a continuum from blue to green.
It's very hard to put a dividing line and say this side is blue, this is green.
That doesn't mean that blue equals green.
So, the fact that it's hard to define life,
doesn't mean there's no such thing as life.
On the other hand, imagine you're a robot,
you've just landed on planet earth,
and you want to describe what you see around you.
Would you choose to make a distinction
between living and non-living things,
or would you just say that there's a lot of complex organic chemistry here?