Life on other planets

Isnt a lot of science based primerily on theory?

In fact all of science is based on theory, or hypothesis. These theories are successful if they accurately describe some phenomena. The acid test however is their ability to predict future unmeasured phenomena.

Einsteins theory of relativity predicted the positions of the planets more accurately than Newtons and so superseded it. It also predicted that large massive objects would bend light. This was demonstrated during a solar eclipse where the position of stars was altered by the amount the theory predicted by the gravitational influence of the sun.

For all that, no physicist would ever say that Einstein was the final word. They would only say he has the best solution so far.

In the case of species not requiring water, there is no evidence that they exist and, as far as I know, no one has proposed a model where life could exist in such conditions. So while not ruling it out, it's not very likely.

Possible, but if life is to be anything remotely like we see on Earth the elements used will need to be able to form into large chains - an equivalent to hydrocarbons in Earth life. The best hope for this is Silicon, its in the same group in the periodic table and can form long chains.

I know but thats my point exactly.....................

WHY should life on any other planet even remotely resemble life on earth. Chances are if it exists it would be so different that we may not even recognize it AS life.

So i guess we DO need a few pointers on what to look out for really.

Paul, maybe when we've looked in all the hen houses then we can look elsewhere. But until then why go searching places where life is less likely. Up to know we haven't even gotten close to looking in all the hen houses.

Look where the water is, if you don't find any there then examine other possibilities

True enough i guess.

Chances are if it exists it would be so different that we may not even recognize it AS life.

I don't want to put too fine a point on it, but why do you say that? The evidence strongly suggests that life forms in a certain way. Earth is nothing special just another ordinary corner of the universe. WHy should life elsewhere be vastly different?

You can speculate all you like about different types of life etc, but until we know better, water is the best there is.

You are also forgetting one other VERY strong possibility. Maybe there is no life anywhere else in the universe?. You may have your views on this but based on current evidence this is a far more likely outcome than speculative silicone life forms etc.

One line you read a lot on astronomy bulletin boards is 'There must be life elsewhere in the universe'. A kind of absolutest statement. But you can't make absolutest statements without evidence to back it up. That is the scientific way. Maybe there is life, maybe not, but until we have some evidence one way or the other then the best we can say is there might be life elsewhere. I'm trying to tie that back to your statement quoted above.
At the moment the chances are that life needs water. That's based on the evidential probability of 100% of the life we have seen so far being water based.

I'm really not trying to knock your ideas Paul, on the contrary maybe one day we will find some wierd type of life. What I'm really getting at is you need to think scientifically otherwise you will always 'just be wondering' and never really getting to the heart of the matter.

WHy should life elsewhere be vastly different?


Why shouldnt it be?

WHy should life elsewhere be vastly different?


Why shouldnt it be?

Because the best available evidence says so!

Possible, but if life is to be anything remotely like we see on Earth the elements used will need to be able to form into large chains - an equivalent to hydrocarbons in Earth life. The best hope for this is Silicon, its in the same group in the periodic table and can form long chains.

I know but thats my point exactly.....................

WHY should life on any other planet even remotely resemble life on earth. Chances are if it exists it would be so different that we may not even recognize it AS life.

So i guess we DO need a few pointers on what to look out for really.

We'll recognise it as life if its there. Does it reproduce somehow? Does it react to a stimuli? Does it adapt to a change in its environment? Does it produce energy from its environment? Those answers are basically what distinguishes life from chemistry. When we look for life we are looking for basic characteristics not chemistry.

Looking around the galaxy though carbon and water rules. We find water and amino acids in nebulae for example. Given that that sort of material is 'lying around' and given that its critical for life here, I'd put money on any life we find being carbon & water based. We cant come up with a way to make silicon based amino acids theoretically (afaik) yet nature manages to mass produce it where stars are forming!

~Albert