No ET! Ever?

[Minimalist]

Can you imagine another planet undergoing the EXACT same kind of events that took place on earth down to a T? It's just awfully unlikely even taking into consideration the size of our universe.

Why do other planets have to undergo exactly the same events that took place on earth?  Evolution selects organisms to reproduce better or worse in a given environment.  Different environments will produce different results.  We might not even recognize an intelligent being from another planet.... and they might not recognize us.

[Amarok]

Shakespeare isn't  life and monkeys aren't evolution

[ErGingerbreadMandude]

Can you imagine another planet undergoing the EXACT same kind of events that took place on earth down to a T? It's just awfully unlikely even taking into consideration the size of our universe.

Why do other planets have to undergo exactly the same events that took place on earth?  Evolution selects organisms to reproduce better or worse in a given environment.  Different environments will produce different results.  We might not even recognize an intelligent being from another planet.... and they might not recognize us.

Okay. So that does make sense but why do we not have aliens in the other planets of our very own solar system that are as much or more older than our own little earth? Shouldn't life have developed in those planets in such a manner so as to survive in that particular environmental condition? Food for thought.

[ignoramus]

Extremophiles! This does prove that life can evolve in very tough conditions, but can any extremophiles ever become intelligent under those conditions? Probably not??? Brian Cox was specifically talking about advanced aliens.

[I_am_not_mafia]

Nah I don't think aliens exist. We already have older planets than earth in our very own solar system. These planets already have had huge amounts of different gasses and chemicals and reactions for more years than earth. Yet, we only find life on earth.

Life is supposed to modify itself to survive in a given environment so the argument that the environmental conditions are severe in other planets falls apart, besides, severe environmental conditions relative to what?

What we see today is over 4.5 billion years of some chemical reactions just happening to take place in the right order, in the right place, under the right circumstances. So 4.5 BILLION years of just seemingly random events taking place in just the right way to give us what we see today. Can you imagine another planet undergoing the EXACT same kind of events that took place on earth down to a T? It's just awfully unlikely even taking into consideration the size of our universe.

I mean, if you have an infinite number of monkeys typing on an infinite number of typewriters you'll eventually get a Shakespeare. Maybe the Shakespeare is us?

There are plenty of places in the solar system that life could exist but we haven't yet visited to check.

You can't assume that life will survive in all conditions. It can only modify itself within a certain range given enough time. So there could have been life on Mars which died out.

It also depends upon how you define life. We're defining it by comparing it to one single sample (i.e. what we find on Earth). The single defining characteristic of life is that it has a metabolism, not that it's intelligent or has two arms and legs.

[Amarok]

Why do other planets have to undergo exactly the same events that took place on earth?  Evolution selects organisms to reproduce better or worse in a given environment.  Different environments will produce different results.  We might not even recognize an intelligent being from another planet.... and they might not recognize us.

Okay. So that does make sense but why do we not have aliens in the other planets of our very own solar system that are as much or more older than our own little earth? Shouldn't life have developed in those planets in such a manner so as to survive in that particular environmental condition? Food for thought.

No not really there is no guarantee of life even in conditions that favor it as the near mass extinction of most off the life on earth thought-out time has shown   

and just because we don't find any in our system doesn't mean much the a hand full of planets out of billions

[Thumpalumpacus]

[...] the other planets of our very own solar system that are as much or more older than our own little earth? Shouldn't life have developed in those planets in such a manner so as to survive in that particular environmental condition? Food for thought.

All the planets in our solar system are roughly the same age.

[Cyberman]

The counter-balance to "Dark Forest" is Greg Bear's "Forge of God". Xenophobic killer alien civilizations would pose a threat to all other worlds. They would face retribution from the empowered remnants of displaced species.

From our perspective, how would we tell the difference between xenophobic species bent on wiping us out and pre-emptive retribution for our own xenophobic killer history?

[Minimalist]

Why do other planets have to undergo exactly the same events that took place on earth?  Evolution selects organisms to reproduce better or worse in a given environment.  Different environments will produce different results.  We might not even recognize an intelligent being from another planet.... and they might not recognize us.

Okay. So that does make sense but why do we not have aliens in the other planets of our very own solar system that are as much or more older than our own little earth? Shouldn't life have developed in those planets in such a manner so as to survive in that particular environmental condition? Food for thought.

And which of those have we visited to know?  The process certainly does not work according to any kind of schedule.  We paragons of development as you seem to think of us have only been sending out radio messages for just over 100 years.  Prior to that we were doing nothing to advertise our existence.  What you are insisting upon is another world which has also developed the exact the same kind of technological society which we have now and which is capable of broadcasting and receiving radio/tv waves into space and also which gives enough of a shit to be listening.  You have too many parameters there.

[Anomalocaris]

[...] the other planets of our very own solar system that are as much or more older than our own little earth? Shouldn't life have developed in those planets in such a manner so as to survive in that particular environmental condition? Food for thought.

All the planets in our solar system are roughly the same age.

Not roughly the same age, exactly the same age to within 1-2%.