Are we alone?

[xelasnave]

Probably no one has ever thought about this question so I ask it now.
Are we alone in the Universe?
I suppose we need to define the Universe before we address the question so I ask is the Universe finite or infinite?
Is there life on other planets or moons out there someplace.
Could that life be inteligent perhaps more inteligent than us.
Of course if you have had personal contact with someone from another galaxy please let us have the details or if indeed you come from another galaxy please use this thread to introduce yourself and share with us your views on Earths inhabitants.
So are we alone or not?
Alex

[bojan]

Considering the size of the Univetse, the number of stars and number of planets... IMO it is very, very, very unlikely we are alone.

But, because I am not alien (I am just another specimenn of Homo Sapiens, born here on Earth), I don't know for sure.

[SamD (Sam)]

Just watched a good BBC4 documentary - "Aliens: The Big Think", with Martin Rees, which gives a pretty good summary of where current thinking is.

[el_draco (Rom)]

Considering the size of the universe, the uniform composition in terms of elements, the principles of physics, chemistry and biology as we understand them, what we know of star/planet formation, the returns from Kepler, what we are discovering in our own solar system about habitable possibilities and the extent to which life will fight to survive here on earth, I'd rate the chances of our planet being the only habitable place in the universe as zero.

I bet Mars and Europa at least will turn up trumps on some scale and that will just make life elsewhere a dead certainty.

[glend (Glen)]

If you accept the Multiverse theory then it is probably impossible the similiar life forms do not exist somewhere, sometime. The problems for humans on earth right now pondering this question is our insignificant time horizon. Even just looking at the probability of life in our single universe, or galaxy, begs the question: At what time? Life may well have existed millions of years before humans on other worlds and faded away again. I agree the probability is high that it has, or will, exist but synchronising with our ability to find them in our brief timespan may mean we never find them. The earth only has so much time to support life, and some might argue intelligent life on earth is already in decline. Getting humans off this world, and out of this solar system is probably the only way to extend the human timespan long enough to increase our liklihood of encountering others. Personally i am extremely pessimistic that humans will survive long enough to reach the technical ability to migrate off world in numbers high enough to grow again on a new world.
This of course was the subject of the recent movie 'Interstellar', which despite the hollywood treatment does tackle some important questions, and touches on 'time paradox'. As we know from human history, there is some luck involved in our species survival and dominance; we cannot always count on that luck in any new world situation.
In our time horizon all we can really do is send out probes and work for a technology breakthough.

[Atmos (Colin)]

I don't believe that there is anything else out there, below is a link to a reason why

https://www.dropbox.com/s/klsv8urzqp...Fermi.pdf?dl=0

[bojan]

Originally Posted by Atmos

I don't believe that there is anything else out there, below is a link to a reason why

https://www.dropbox.com/s/klsv8urzqp...Fermi.pdf?dl=0

Colin, believing is one thing, knowledge is another (as I know you are perferctly aware of this fact).

I always found fascinating the analisys of Fermi paradox based on economical factors.. but this may well be most important factor there is.
Look at ourselves.. we (humans.. at least most of us in the richest countries on Earth) cant even take care of our own future generations (education, health..) because it is too expensive and doesn't bring immediate profit for investors..

[Stonius (Markus)]

As time goes on with increasing evidence of extra-solar planets, yet no evidence of Extra Terrestrial Intelligence (ETI's), it pushes us towards one of four possibilities

• They don't want to be found. Make of that what you will.
• We're looking for the wrong kinds of telltale signs, or in the wrong places. Perhaps their technology has advanced such that it no longer resembles our own.
• The factors that lead to technological advancement usually also lead to it's own destruction.
• There *are aliens and they're already here. I mean have you *seen Donald Trump? The guy is orange!

Hopefully it's the second one.

[Stonius (Markus)]

Of course, a true Nihilist would say 'We are all alone'.

[FlashDrive (Poppy)]

Originally Posted by Stonius

• There *are aliens and they're already here. I mean have you *seen Donald Trump? The guy is orange!

ha ha yeah he does doesn't he ...!!

[gregbradley]

It would seem the funny idea is that we are alone. The only "proof" of that idea is the fact we don't have aliens dropping by trying to sell their products like some overseas country or trying to take over our society.

Perhaps that's just because we are a long way out.

How many have been to the red centre lately?? Not many people there either!

Greg

[AstralTraveller (David)]

Originally Posted by Stonius

As time goes on with increasing evidence of extra-solar planets, yet no evidence of Extra Terrestrial Intelligence (ETI's), it pushes us towards one of four possibilities

• They don't want to be found. Make of that what you will.
• We're looking for the wrong kinds of telltale signs, or in the wrong places. Perhaps their technology has advanced such that it no longer resembles our own.
• The factors that lead to technological advancement usually also lead to it's own destruction.
• There *are aliens and they're already here. I mean have you *seen Donald Trump? The guy is orange!

Hopefully it's the second one.

AFAIK we couldn't even detect oxygen in the atmosphere of an extra-solar planet. It's not so much looking for the wrong telltale sign as not yet being able to detect the most obvious smoking gun. Until we can do that, the best we can say is that they haven't knocked on the door. Of course we haven't knocked on theirs either and we're here (though I'm not all here).

[vlazg (George)]

I think glend has put it succinctly and correctly. I'm sure there has, or will be intelligent life somewhere but the chances of it coinciding with us is very, very small due to the large timescale and the short lifetime of any civilization.
Read Jared Diamond " Collapse "

[strongmanmike (Michael)]

The biggest piece of evidence that there must be life elsewhere in the Universe is the fact that it exists here...if life evolved here on Earth, it is clear there is at least one mechanism for it to happen, so why not elsewhere?

[Max Vondel (Peter)]

Originally Posted by Atmos

I don't believe that there is anything else out there, below is a link to a reason why

https://www.dropbox.com/s/klsv8urzqp...Fermi.pdf?dl=0

I agree Colin....we are alone

But I wanted Star Wars and Star Trek 2b so true!

[Max Vondel (Peter)]

Originally Posted by strongmanmike

The biggest piece of evidence that there must be life elsewhere in the Universe is the fact that it exists here...if life evolved here on Earth, it is clear there is at least one mechanism for it to happen, so why not elsewhere?

Anthropomorphic reasoning doesn't help
Because life is abundant here...doesn't translate to the other places in the universe. Dolphins are intelligent but don't build radio telescopes or space capsules

[Max Vondel (Peter)]

Originally Posted by el_draco

Considering the size of the universe, the uniform composition in terms of elements, the principles of physics, chemistry and biology as we understand them, what we know of star/planet formation, the returns from Kepler, what we are discovering in our own solar system about habitable possibilities and the extent to which life will fight to survive here on earth, I'd rate the chances of our planet being the only habitable place in the universe as zero.

I bet Mars and Europa at least will turn up trumps on some scale and that will just make life elsewhere a dead certainty.

I'm sure microbes are abundant in many parts of the universe
If we find life on neighbouring planets, its only likely to mean transfer of micro organisms from one place to the other via meteorites, collisions etc. In other words, If we find other life in the solar system it will say nothing about life among the stars.

However finding microbes is different to finding a space faring communicating civilisation by many orders of magnitude.

The Nick Bostrom .."Simulation Argument" is much more likely

[deanm (Dean)]

As a molecular geneticist, the fundamental basis of life on earth was the evolution of self-replicating molecules which contain & propagate information.

That's the hard part, but a lot of chemistry can happen over a few billion years.

Once you have self-replicating molecules, the subsequent development of cellular structures, then multicellularity, is pretty straightforward.

So *life* can readily evolve. However, intelligent life is a different proposition.

Dean

Dean

[strongmanmike (Michael)]

Originally Posted by Max Vondel

Anthropomorphic reasoning doesn't help

I didn't say Anthropomorphic, just "life" of some form

Because life is abundant here...doesn't translate to the other places in the universe.

But it is certainly evidence that it can happen...doesn't necessarily need to be "abundant" either

Dolphins are intelligent but don't build radio telescopes or space capsules

true but kind of irrelevant to whether "life" may exist elsewhere..?

[xelasnave]

It is difficult to comprehend just how many galaxies are out there.
Consider my simple conservative approach.
The Hubble Deep Field photos show approx. 2500 galaxies.
The field of view is what a grain of sand covers if held at arms length.
For various reasons we can say wherever you cover the sky with a grain of sand there will be approx 2500 galaxies behind that grain of sand.
Each galaxy say averages a billion stars and arguably more we get to dizzy numbers.
Say each galaxy has a 1 in 1000 chance of life extend it to
1 in 10000000 the odds will remain high.
We do not understand how life "starts" but I will bet it is merely an extension of chemical reactions.
I know how it starts but I won't bore you with the details other then to say