Quote:
Originally Posted by spiderbaby
Our solar system is around 5 billion years old. The universe could be as much as 20 billion. Intelligent life, us, has existed on this planet for an upper window of around 100,000 years. If intelligent life is common in the universe it should have popped by to say hello by now. This leaves us with only a few alternatives.
1) Life is not common.
2) Intelligent life is not common.
3) Travel between solar systems is effectively impossible in any humanly achievable time scale.
So I voted for life is rare because it seems like the lesser evil.
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Hi Spiderbaby and welcome to Cr!! Always nice to have another ...erm...mammal on board
Analysis using spectrography shows us that the universe is abundant in both water and the basic building blocks of carbon based life. Looking at life on Earth we see how tenacious it is, life exists from high in the atmosphere to deep within the continental crust. I think it common everywhere. But to have the stability to create the right conditions for evolution to proceed long enough for a space faring civilisation to emerge is another matter. On Earth for example we not only enjoy being in the goldilocks zone around the sun where water can exist as a liquid. We have a moon of just the right size and distance to drive plate tectonics/volcanism that sustain the availability of the essential minerals over time. Without this alone life on Earth may still exist but it would be sparse indeed compared to what we see. Additionally our solar system is sufficiently uncluttered by debris left over from its creation that we are not continually facing meteorite impacts that knock evolution to the floor every few 1000 years.
A planet much bigger than ours would present huge problems in achieving the velocity required to escape its gravity. One much smaller than ours could not support the kind of rain bearing clouds we are absolutely dependent on. The balance required for all the conditions we find here must be pretty rare but not impossibly rare. And of course it would be naive to assume all intelligent life is anything remotely like us.
We have been sending a beacon of our existence for a very short time. And in truth even our most powerful radio signals once they leave the solar system and hit the interstellar radiation become just noise. If nothing has been to visit it is no surprise. The universe is pretty big after all.
As you pertinently mention interstellar travel presents huge technological problems. We have difficulty providing effective shielding for our current toe dip into the vast ocean of space. Aside from the constraints of relativity the hostility of interstellar space presents us with problems we do not yet have the ability to meet. Leaving our atmosphere for orbit is small change compared to leaving the balmy comfort of the Heliosphere protecting us from radiation found in the interstellar void. Thank god we have star trek!!
Tao