When you look at how thin the oceans are, it’s amazing that we aren’t completely water covered. And if that’s the case, you can easily have tons of life, even advanced life…even intelligent life. But technological life?

That’s not quite true though. You can go anywhere from sub-zero frost to boiling sulphur springs and find life. There is even life kilometres below the earth’s surface.

This is true, but you find less and less as you get away from the “water available in the range of 0 – 40 °C” zones.

Yes, there are bacteria that live in antarctic glaciers, but they have to excrete proteins that melt the ice in which they live (just a tiny bit) so they can absorb nutrients and grow. Yes, there are thermophilic bacteria, but the higher the temperature of the spring, the fewer species you will find.

There is bacteria found living (and mutating) on the external surfaces of our satellites.

Citation needed.

Look at the humble waterbear that can survive all sorts of extremes- although granted needs more temperate environment to thrive and reproduce.

And, more imortantly, to metabolise. They survive extreme conditions (radiation, vacuum, dessication (sp?)) by going dormant. It’s hard enough to identify life from a distance when that life is active, but to detect dormant life from light-years away would be very much more challenging.

It may be that life on our planet prefers the cushy temperate zones- but life that evolved from different chemistries would not have the same requirements.

Absolutely correct, and completely useless. Without knowing something about this other life, how could we ever begin to come up with a way of detecting it from a distance?

That’s not quite true though.

Yes it is. The post you were responding to was describing the whole earth, not just the surface. There is no life in the mantle, no life in the core. Even on the surface there are large swaths of Antartica that are sterile, and regions in the Atacamba desert that are sterile.

You can go anywhere from sub-zero frost to boiling sulphur springs and find life. There is even life kilometres below the earth’s surface.

All these examples still constitute only a thin fracture of the surface crust of the earth. As extreme as they are from our human perspective, even from the perspective of the rest of the earth, they are not extreme at all.

It may be that life on our planet prefers the cushy temperate zones- but life that evolved from different chemistries would not have the same requirements.

But that begs the question, if it really is so easy for life to appear with such different chemistries, as to why life didn’t evolve with these different chemistries here on earth in those zones with those different requirements. Certainly it is not the life-as-we-know-it outcompeting them, since life-as-we-know-it does not and cannot survive in those parts of the earth.

And to reiterate, when you contemplate a voyage into the unknown, it is true that you should always keep an open mind about your destination. However, you must still embark from a familiar port. There is no other way to do it.

“… they won’t speak English as their native language.?

That’s ok. We’ll just give them our Universal Translator.

About the best definition I’ve heard for life is “any pattern of mass/energy that is both self sustaining and self replicating”. That pretty much covers anything from solid state electronics to plasmas.

,,,and these squishy bags of water,,,

Gary 7

==============================

That’s not quite true though. You can go anywhere from sub-zero frost to boiling sulphur springs and find life. There is even life kilometres below the earth’s surface.

There is bacteria found living (and mutating) on the external surfaces of our satellites.

Look at the humble waterbear that can survive all sorts of extremes- although granted needs more temperate environment to thrive and reproduce.

It may be that life on our planet prefers the cushy temperate zones- but life that evolved from different chemistries would not have the same requirements.

How to look for life that is different to ours when we don’t know what it will be? Look for the “un-natural”- look everywhere. Look to see what seems to violate the norms. There is most likely life out there- but it almost certainly doesn’t look like us… and no matter what the sci-fi lovers would like to believe…

… they won’t speak English as their native language.

However, I can’t help but believe we will find that our code- DNA is not the centre of all life. Water may not be a requirement.

If there is life out there we could well turn out to be the exception not the norm as to how life is. There could be lots of life out there, we just don’t know where/how to look for it- because we’re busy trying to find our mirror image.

OK, this is plausible, as far as it goes. What do you suggest we do about it? Stop looking for life that is like Earth life and start thinking about ways to detect life that is inconceivable to us? How should we go about this?

The problem with life that is not as we know it is simply that – we don’t know how to recognise it. We still have trouble coming up with a definition of “life” that actually applies to all the life we do know about here on Earth.

In the meantime, I’m quite happy that folks are seeking out new life elsewhere, on the basis that life out there might share some fundamental parameters with life here.