Is the solar system special?

[Venusian Broon]

Whoa, that would represent some serious levels of sensitivity!

Well, one is full of hope for such a telescope, it has loads of lnteresting targets other than planets, saggitarius A*, the first stars etc....but no doubt as soon as it goes up, they will find something wrong with it that hinders it a 'la Hubble

 

[Vertigo]

Well, one is full of hope for such a telescope, it has loads of lnteresting targets other than planets, saggitarius A*, the first stars etc....but no doubt as soon as it goes up, they will find something wrong with it that hinders it a 'la Hubble

I thought you were the optimist a few posts back!

 

[Venusian Broon]

I thought you were the optimist a few posts back!

About the cosmos, humans are naturally error prone.

 

[RJM Corbet]

@Venusian Broon
Thanks for the video

I think life is far more subtle than the carbon or silicon based, liquid water dependent life forms that we as humans are looking for. I think perhaps life exists pretty much everywhere in the universe, including our solar system, but we don't even know what to start to look for. I mean, we couldn't recognize it as living by the terms we understand?

Our truly brilliant science is still just always an ingenious way of extending the perception of our natural senses of sight, hearing and so in, to an jncredible degree. Watching that Mars lander sequence was to be blown away by the imagination and capablity of these scientific people to calculate and design and engineer to the Nth degree. Wonderful.

But IMO there may be senses and dimensions beyond our ability even to conceive.

Perhaps our stunning 21st century technology is indeed starting to demonstrate just how scarce may be the fine-tuning parameters for life as we know it to originate, at least within any range of ourselves that we can ever hope to test.

Holding breath for the James Webb, finally set to go after all the years. More nail biting stuff ...

 

[RJM Corbet]

Repeat posting. Mods please delete

 

[paranoid marvin]

@Venusian Broon
Thanks for the video

I think life is far more subtle than the carbon or silicon based, liquid water dependent life forms that we as humans are looking for. I think perhaps life exists pretty much everywhere in the universe, including our solar system, but we don't even know what to start to look for. I mean, we couldn't recognize it as living by the terms we understand?

Our truly brilliant science is still just always an ingenious way of extending the perception of our natural senses of sight, hearing and so in, to an jncredible degree. Watching that Mars lander sequence was to be blown away by the imagination and capablity of these scientific people to calculate and design and engineer to the Nth degree. Wonderful.

But IMO there may be senses and dimensions beyond our ability even to conceive.

Perhaps our stunning 21st century technology is indeed starting to demonstrate just how scarce may be the fine-tuning parameters for life as we know it to originate, at least within any range of ourselves that we can ever hope to test.

Holding breath for the James Webb, finally set to go after all the years. More nail biting stuff ...

I agree. Our criteria for what we deem as 'life' and what conditions are possible for life to exist in are far from definitive. I think not long ago creatures found living at the bottom of the ocean existed in conditions which thought impossible for life; and that is on our own planet!

In terms of exploring the galaxy (never mind the universe) we are still at the stage of sticking a sand into the desert and hoping to discover buried treasure. Though I suspect that the human race, in the brief moment of time allotted to us, will never expand beyond our home here on Earth, and many of the mysteries of the Universe will never be revealed to us. Which is a shame.

 

[RJM Corbet]

I agree. Our criteria for what we deem as 'life' and what conditions are possible for life to exist in are far from definitive. I think not long ago creatures found living at the bottom of the ocean existed in conditions which thought impossible for life; and that is on our own planet!

In terms of exploring the galaxy (never mind the universe) we are still at the stage of sticking a sand into the desert and hoping to discover buried treasure. Though I suspect that the human race, in the brief moment of time allotted to us, will never expand beyond our home here on Earth, and many of the mysteries of the Universe will never be revealed to us. Which is a shame.

And possibly other life-forms would look right past us, as we would them, unable to recognise one another as living entities?

Why should man be unable to regard or recognise the Earth and other planets as living entities? Do fleas recognise the dog they're on, lol?

 

[Justin Swanton]

Another way of looking at the solar system is to see it as it is rather than as we hope it will be. What it is, is a dramatic contrast between Earth and everything else. On Earth life can exist from about 2km underground to about 6km above the surface. That's a sliver 8km thick. Everything outside of that sliver is intensely hostile to life. In space a human can hope to survive, unprotected, for about 90 seconds. The most resilient organism, the tardigrad, might last a week. No planet lengthens that survival time and most shorten it. The delicate and fantastically complex structure of carbon-base life forms requires some very specific conditions to exist and only the surface of the Earth supplies those conditions. The universe as a near-total whole is not for us. But it is very beautiful.

 

[M. Robert Gibson]

Obligatory Douglas Adams quote

“It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any people you may meet from time to time are merely the products of a deranged imagination.”

 

[paranoid marvin]

I also like his other quote

'Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.'

I miss Douglas Adams.

 

[Extollager]

What will be the social consequences if civilization persists on this planet, even space exploration continues, but in 50 years there is still zero evidence for life anywhere else?

 

[Justin Swanton]

What will be the social consequences if civilization persists on this planet, even space exploration continues, but in 50 years there is still zero evidence for life anywhere else?

Nothing will change. We'll still be convinced there's life out there somewhere. Personally I'm not convinced, but it's easy to argue that humanity could continue another million years on Earth and never become aware of life on other planets since the distances are just too great, even for signals.

 

[Elckerlyc]

Hardly any, I would think. A lot less anyway than would be the case if evidence for alien life were actually found. "Be patient," they'll say, "Give it another 50 years, when we are able to leave our own solar system." The universe is too unimaginable vast to allow anyone to say at any one point, "We searched everywhere, without result. Now we're certain we're alone."

For most of human history the notion of alien life was totally... alien. Until about 100 years ago. Since then the awareness of the possibility has slowly grown more common, but hardly generally accepted. Is all highly hypothetical and will remain just that as along as evidence is lacking.

 

[Extollager]

I do wonder about how the stubborn non-appearance of evidence for extraterrestrial life might affect large numbers of people, most of whom will not have a firm grasp of the vast distances, etc. The fact is that popular entertainments and so on endlessly reiterate the idea that the discovery of an advanced civilization is only a matter of time.

For example, a poll from four years ago:

Poll Shows What Americans Think About Life On Other Planets

Poll Shows What Americans Think About Life On Other Planets

www.huffpost.com

That's a lot of people who believe that there is some sort of scientific evidence for extraterrestrial life. So it's a part of popular consciousness.

Thus I do wonder what might be the situation in 50 years if there's no more real evidence then than there is now for "life." Will people have been prepared to accept this by, say, their high school teachers, to counterbalance the common notion?

It would seem that popular entertainment would stick with the theme as long as it sells movies, games, TV shows, and so on. On the other hand, wouldn't it seem strange to us if, in 10 or 20 years, nobody was producing such material? If all of the familiar productions about extraterrestrial life were as dated as, say, Western movies seem to be today?

When the Western was king, sf was really pretty marginal.

 

[paranoid marvin]

There will always be speculation of the 'what if' of extraterrestrial life. The world of sci-fi fiction is safe; look at War of the Worlds - over 100 years old, and long since disproven that life exists on that remote, forbidding planet. Yet the story is still going strong with tv series and movies.

But as has been said, the universe is too vast and our methods of determining life too inadequate to determine the possibility of life - or not - on worlds thousands of light years away.

 

[paranoid marvin]

Nothing will change. We'll still be convinced there's life out there somewhere. Personally I'm not convinced, but it's easy to argue that humanity could continue another million years on Earth and never become aware of life on other planets since the distances are just too great, even for signals.

Distance is a definite factor, but perhaps moreso is time. Due to the age of the universe, galaxy, planets and stars I'm not sure how many signs of life could be easily traced several billion years after it lived, thrived and then died out. Perhaps up close, but certainly not from telescopes or satellites light years away.

I agree though, that even if we exist for another million years, meaningful contact with an alien species is a remote possibility. I still do think though that we will (eventually) find basic forms of life on one of the water-based moons of our solar system, and even the fossilised remains of life beneath the surface of Mars. Although I don't think we'll find evidence on Mars unless/until we send a manned mission there.

 

[Justin Swanton]

I still do think though that we will (eventually) find basic forms of life on one of the water-based moons of our solar system, and even the fossilised remains of life beneath the surface of Mars. Although I don't think we'll find evidence on Mars unless/until we send a manned mission there.

I know, we're all hoping for something from Europa. But the idea that the moon has a subsurface ocean of water is speculation and not proved. Besides water, life would need a source of energy and there is nothing on Europa that would demonstrably fit the bill. The temperature on the surface varies between -160 degrees and -220 degrees C, so life could not get anything from there. The only chance is subsurface volcanic activity and we still need evidence that Europa has a sufficiently hot core. Given that the surface ice may be 10-30km deep (presuming there is water below it) we may never be able to determine if there is life underneath.

For Mars we don't have any proof that surface conditions could ever accommodate life. There is evidence water flowed on the surface some time in the past but under what conditions (a cataclysmic upheaval that melted subsurface ice and drove it to the surface?) and for how long is unknown. I prefer Occam's Razor: Mars doesn't have a magnetic field hence gamma rays and solar flares would be a huge problem for anything on the surface. Its lighter gravity combined with solar wind was enough to strip most of its atmosphere a long time ago. I see no reason to suppose it ever supported life.

 

[Vertigo]

since the distances are just too great, even for signals.

I can never understand why so many people ignore this fact. Everyone seems to think that after we started broadcasting radio and tv it was only a matter of time before the signals get picked up by alien civilisations. however these signals were/are not focused they are omnidirectional broadcasts and not particularly strong ones at that. This means that they are subject to the inverse square law and so their strength diminishes incredibly quickly. I looked into this a few years ago and found multiple sources showing that, beyond something like a light day or two (never mind light years), our signals were tiny compared to the background radiation and were already pretty much undetectable. Note this is in complete contrast to our ability to receive signals from, say, Voyager; although its transmission is incredibly low power it is focused and directed back to Earth using parabolic dishes. So the only way our signals would stand any chance of being detected over interstellar distances is for them to be focused and directed at exactly the right stellar system at exactly the right time for Mr Alien to be pointing their incredibly sensitive receiver directly at our solar system also at exactly the right time. The chances of that happening make winning the lottery look like a certainty.

Of course exactly the same principle applies to us detecting any alien broadcasts.

Then of course there's the other possibility that any aliens out there are sensible enough to keep their heads down anyway and not go announcing their presence to the rest of the galaxy!

 

[Extollager]

Vertigo, that long paragraph is one of the most instructive things I've ever read on this topic -- thanks.

 

[Vertigo]

Let's hope my facts are right. I seem to recall when I was investigating it that about the only thing we have that would realistically communicate across interstellar space is high power radar - but again this is highly directional.

A quick bit of googling seems a little more optimistic than me with 4-5 light years before it is undetectable ie. the signal is less than 1db above background noise.

I just removed one bit that I think was a mistake where I stated that a signal focused by a parabolic dish is not subject to the inverse square law. I think this is incorrect; it's just that such a signal has all it's available power directed in one vector rather than being spread all around in every direction making it relatively more powerful.

Incidentally the Three Body Problem gets around this issue by effectively modulating the sun's output. Now that's one seriously powerful radio transmitter!