Life in the Universe?

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Richard
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Life in the Universe?

Postby Richard » Thu Nov 23, 2017 10:38 pm

It is generally understood that life-forms only arise and develop when certain favourable conditions are present on a 'goldilocks' planet, near enough to receive just the right amount of energy from a nearby 'sun', a star by any other name.
Something like an iron-core is needed in order to deflect the life-damaging radiation which stars naturally emit and additionally would otherwise prevent a life-sustaining atmosphere from forming.
Even given such ideal conditions, it is generally understood that life on Earth arose and developed from primitive single-celled organisms to more complex forms, only by evolution and by pure chance.
Mass extinctions (e.g. of the Dinosaurs) as a result of external catastrophe, meteorite(s), altered the course of evolution, such that mammals and man eventually appeared as the dominant life-foms.
Favourable conditions must also hold true for life in the Universe and the same sort of process, of evolution and extinctions, may (or not) have resulted in a life-form with higher intelligence.

It follows that life anywhere else in the Universe would be neither an intelligence in human-like form, nor an intelligent version of the dinosaurs, the typical S.F. reptiles or weird creatures, it's never going to happen!

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seahermit
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Re: Life in the Universe?

Postby seahermit » Fri Nov 24, 2017 2:11 am

This topic is endlessly fascinating. Logic would in theory suggest that, amongst the many planets which must exist in orbit around the countless suns/stars, some atleast must have reached ideal conditions for life to form - or atleast adequate conditions for some sort of life forms. No evidence discovered so far. It's of course more complicated than that, since life forms are now being discovered on earth in very unlikely places - near immensely hot springs at the bottom of deep and lightless oceans etc. So life doesn't actually need ideal conditions of light, air and all the rest!

One assumption often made is that alien life will be intelligent - they may well be thick as two planks and unable to communicate even with each other! And rather than having any chance of appearing on Page 3, they may look more like the main character in "The Blob" ...

By the way, I think it was a meteor which is thought to have exploded above the earth's surface (didn't actually hit it) and put paid to the dinosaurs. Meteorites are the small fragments which get through and can sometimes be found littering the landscape.

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Richard
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Re: Life in the Universe?

Postby Richard » Fri Nov 24, 2017 1:33 pm

It's true, primitive life forms have been found around 'geothermal vents, at the bottom of the deepest ocean trenches, where hot lava spews up along the cracks in the crust, surviving in conditions of immense pressure and incredibly high temperatures.
Also at extremely low temperatures, in and under the massive ice sheets but I don't think anything resembling life has been found if water is not present and that seems likely to hold true for any other planet. Assuming life out there would be recognisable as such and of course 'Star Trek' has played with countless scenarios enough to boggle the mind and stretch credulity.

Very primitive life is unlikely to have any of what we recognise as 'intelligence', it took billions of years for highly developed multi-celled organisms to arise and almost anything could alter the course of its evolution along the uncertain path or even wipe it out (in the case of the dinosaurs and the meteor-burst cutting out the sunlight to larger forms of plant life).
It looks like primitive life can only live where there is some form of water and more advanced forms would require the 'goldilocks' conditions of water, air, temperature, i.e. an atmosphere to be present before they could reach even better pastures on the earths surface.
And of course the development of an atmosphere required plants to produce oxygen, in preparation for life to emerge on land and only on a planet that could hold onto its oxygen via an atmosphere and by virtue of it's dense core that deflected deadly solar radiation.

There have been many branches along the tree of mammalian life and even the primates are not that intelligent, exactly how humans arose is uncertain but it strikes me that some are not all so clever and many will resort to aggressive, base animal instinct (originally necessary for survival) and fight over territory and rivals just the same.
If we were created by God, as a special 'being' apart from animals, why would he have given us the same insticts?
We are also vulnerable to war and disease and now our numbers are too large, a virus may easily evolve to kill a good percentage of the world population but that may be no bad thing, cruel as it sounds.

Viruses are alien-life forms to my mind, living in a twilight world, in fact they are not even 'alive', they lack essential systems necessary for metabolic functions, the biochemical activity of life.
So, what exactly defines life, just the posession of genetic material and an ability to replicate?
Viruses have their own, ancient evolutionary history, dating to the very origin of cellular life, they are sometimes defined as parasites on life, and have developed many clever ways to avoid detection by the host immune system — essentially every step in the immune process can be altered or controlled by various genes found in one virus or another.
More astonoshing, there are vast numbers of completely 'harmless' viruses that live inside organisms (from bacteria to plants to animals) and can alter and control gene function and may have changed evolution much more quickly than external forces alone could muster.
Some scientists believe the nucleus of our cells was adapted from a resident virus!

I suppose the real reason now for believing in and finding 'safe' primitive life forms on other worlds is that one day such places may be needed for our survival, as we reproduce without end.
Planets without higher intelligence to compete with would be absolutely perfect candidates for human expansion - not sure about the 'foreign' viruses...!

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seahermit
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Re: Life in the Universe?

Postby seahermit » Fri Nov 24, 2017 4:54 pm

This is all fascinating and informative, clearly "your" field. I'm even going to print it out for a friend of mine to read, hope that's ok?! Very nicely and concisely explained.

I am sceptical of humans migrating in large numbers to another planet, think it's a pipe dream. We are running out of time to achieve that. Nature's way amongst living creatures has always been, when over-population is happening, to reduce numbers by aggressive competition for territory and resources, by disease and lack of food. That is exactly what is happening now. There have been countless wars since WW2, many famines, and several potentially devasting viruses and epidemics. It is only a matter of time before a new virus develops faster than medical research can find antidotes, or before population growth seriously starts to excede our ability to find additional food supplies.

It would be very difficult to restrict/slow population growth across the world in any way which was meaningful (or acceptable to people's natural instincts). And to enable humans to escape to other planets in large numbers, there would have to be a very disciplined, focussed harnessing of all industrial, technological and financial resources. Maybe possible in some kind of totalitarian state, but currently our modern societies are too fragmented, internally unstable and constantly at war with each other to be able to rely upon that kind of solution.to our problems. Even if nations could settle their petty differences and combine their skills and resources, we are very far from the level of technology required to seriously colonise space and time is running out - we are living in a dangerous, unstable period of history and we haven't learned lessons from rhe past. Still fighting over religion, political ideologies and territory.

Pessimistic but then one has to be aware of the real threats. Life has always been precarious and unpredictable. Ancient Greek city states, despite their wonderful flowering of art, civilisation and democratic ideals, lived under the constant threat that political forces beyond their control could at any time completely destroy their culture and existence. As indeed happened to almost every one of them.

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Richard
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Re: Life in the Universe?

Postby Richard » Fri Nov 24, 2017 6:59 pm

MJ, I am surely flattered if you want to print out my blurb.

Regarding space colonisation:
At the start of 2016, Prof., Stephen Hawking warned about the dangers from nuclear war, global warming, asteroids, genetically-engineered viruses, population growth and artificial intelligence.
Stating that humans must colonize another planet within 100 years or face extinction.
Is it better that he sticks to talking about black holes and quantum mechanics? Not that I understand much of that.
I think we are probably much better off on our fragile planet Earth than trying to set up home on another planet and the only ones near enough are in our own solar system anyway and are pretty miserable, too cold with different gravities from what we are used to and certainly no air with oxygen to breathe, we would have to live in artificial life-support structures.
However, there have been a few space stations set up aimed toward wider space exploration.
The NASA 'Skylab' project, followed by the USSR/Russian 'MIR' and finally the International Space Station in 2010.
Skylab suffered orbital decay in 1979 and so did MIR in 2001 (built on the Salyut model) and are both finished but the ISS, represents a joint international programme intended to act as a staging base for possible future missions to the Moon, Mars and asteroids.
I don't think in any way that there is any chance of getting to the nearest potentially inhabitable planet outside the solar system in 100 years time, so the future for escaping Earth looks pretty thin.
I think 'terraforming' suitable planets outside the solar system looks like pure Science Fiction.
It would take too long to get there, let alone find one(s) that were remotely suitable.
As for 'Time-Travel', beloved of S.F. fans, this is only ever possible going forward into the future and only likely in the sense that as you travel faster and faster towards the speed of light you age more quickly, compared to people you had left behind on Earth and so that is probably a non-starter too.

If the Universe is infinite there must be other life-forms out there but we will never know.
That doesn't bother me a great deal but the idea of infinity is rather curious, it's a concept and much like the biggest number, which is theoretical and can never be reached, it too should have a starting point and bounds which are, however, always increasing, or always possible to grow since the Universe is expanding under its own power and, unlike numbers it occupies actual space.
The question in my mind is what exists beyond the Universe if it is currently finite and limited, but still expanding, i.e what it is expanding into if it is just potentially infinite?
Again, the mind boggles...

Dark matter and Dark energy can wait for now.

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seahermit
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Re: Life in the Universe?

Postby seahermit » Fri Nov 24, 2017 9:45 pm

Yes, I agree about all that. The difficulties of even getting to another planet suitable for colonising, then importing all the equipment needed to carry out mining and engineering works to enable human beings to exploit the natural resources and create a habitable infrastructure, would involve such massive technical challenges and financial outlay that we do not have that capability within the foreseeable future. Apart from the fact that we haven’t yet discovered anywhere viable to colonise!

I suppose that in theory it is possible for a few humans (select ones/wealthy/scientific nerds?!) to one day manage an escape to some other planet, but it is unlikely that those few humans would themselves have enough resources to meet the massive challenges of trying to build up a long-term or permanent settlement. It would surely only be practicable on a large scale. As for the rest of us plebs, don’t imagine for a moment that seats will be made available for us on the bus!

The question of what lies beyond the universe is indeed mind-boggling. If the universe must be expanding into something else, maybe there is something greater than the universe – one school of thought believes that there may be countless other universes .. infinitely!

Apparently, on a bus journey my brother when aged ten asked my mother “Who made God?” There was a very long awkward pause whilst the whole bus waited for her reply …

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Richard
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Re: Life in the Universe?

Postby Richard » Sat Nov 25, 2017 5:36 pm

It remains to be seen whether 'life' is a natural consequence of the big bang and the arrow of time. The arrow of time suggests that entropy moves in one direction only and that this is irreversible, all things being equal. In other words organised matter has a tendency to break down in time and form less organised states (of higher entropy):
An egg or a glass can be smashed by dropping and the reverse will never occur, an omelet will not revert back into its constituent eggs.
We only exist on the face of this reality, a Universe that is, in other words, decaying, not necessarily depressing or dismal, just the way things are and will always be to our reality.
In the Rubyat, the poet Omar Kayyam instinctively summed up this 'march of time' in one direction only, more succinctly:

'The Moving Finger writes; and, having writ,
Moves on: nor all thy Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all thy Tears wash out a Word of it.'

We can't be un-evolved, there is only one direction forward, although many different outcomes are possible and we should be grateful that we are the latest known intelligent life-forms available that are capable of trying to make any sense of the universe.
Life is the only force that is capable of producing consciousness and this alone is a very interesting concept.

My favourite is the Monty Python ditty:

https://www.youtube.com/watch?v=hkkjzmu ... y%20Python

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Richard
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Re: Life in the Universe?

Postby Richard » Mon Nov 27, 2017 9:12 pm

I think perhaps the question is not is there life in the universe? There probably is, but how do we detect it? Bearing in mind that it will be somewhat different to the types of life that have evolved on Earth. It may just be very primitive.

We have sent out messages to various planets in our solar system and beyond into deep space, aimed at distant stars with planets.
In 1962 a radio message in Morse code was transmitted and directed to the planet Venus.
Since then many more messages, some by radio frequency, have been sent to a huge number of possible 'candidate' stars with planets.
Physical messages like that of the Pioneer plaque placed on board the 1972 Pioneer 10 and 1973 Pioneer 11 spacecraft, featured a pictorial message, in case it is intercepted by extraterrestrial life. The plaques show the nude figures of a human male and female along with several symbols that are designed to provide information about the origin of the spacecraft and life on Earth.
In 1974 humanity made its most famous effort to send a signal to the stars. It was a radio transmission sent from the Arecibo observatory.
Being more proactive than just broadcasting our own existence into deep space there are ways in which we can remotely examine nearby planets for signs of life, but unless our space probes can actually arrive safely to carry out this work it looks like a lot more research and development is needed.
Britain's first probe to another planet, the ill-fated'Beagle 2' lost contact on its decent to Mars in 2003 and was never able to operate.
The tiny craft was 'lost' for 12 years until NASA's Mars Reconnaissance Orbiter (MRO) spotted it on the surface of Mars in 2015. 'Beagle 2' had made it safely to the surface but was crippled when it could not link up to Earth owing to a faulty motor and a very rough landing, it had just a single parachute and air-bags to cushion the probe on impact.
Packed full of sensitive apparatus, Beagle 2 was supposed to sample rocks and soil, seeking signs of life by looking for carbon signatures.
Mars is a death-trap for landing. It has a very thin atmosphere and its density changes enormously, so you have to have parachutes and heat shields that are adaptable.

Any aliens looking for us will have to rely on evidence, such as the indication of water in our atmosphere or chlorophyl on Earth’s surface, just as we will strive to detect such things on distant worlds.
It is clear that radio signals can travel faster than any type of probe, however these require enormous amounts power to travel as the energy decreases rapidly with distance.
This gets better if we focus the transmissions exactly on a target planet but also narrows down the chance of hitting on one in a million.
Whatever signals are used that can travel faster and further than probes it is clear that if the nearest intelligent life that might be able to understand or decode them will have become extinct by the time it takes because the distances are millions of light years away and therefore any civilisation reading them or receiving them would probably be extinct by the time they had been received.
Humans are thought to be only 2.5 million years away from the time they began to evolve from Apes and it would take longer than that to the nearest potentially inhabitable planets around distant stars.

Also I think we have to turn the tables, imagine the shock and excitement if signals were detected from deep space that indicated an advanced highly intelligentlife-form.
But the distance would make it a false hope that anything remained (or remaine remotely the same) and especially if it took the same length of time to issue a response.
But if signals had been sent from such a distance they would not likley be repeated unless or until they had received a response (and vice-versa).
Because of the time-lag constraints alone maybe it's never going to happen!
8-)


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