Extraterrestrial Life in Our Solar System

"The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us." --Calvin and Hobbes

GA Roger

You said it.

You assumed pessimistically only carbon based life. But I would like to add that there is no reason to think that the life can be only carbon based. There is no reason to assume than life needs water and oxygen. There is no reason to assume that ultraviolet kills the life.

We adopted to certain conditions, thus we can not survive beyond these conditions (water, oxygen, absence of UV). But other life may groom on some other conditions. Who knows.

I read Roger's post myself with great interest. I got through one of the bluelined links and part way through the pdf sort of thing.

There have been some discussions concerning possibilities for silicon based life, as opposed to carbon based.

The search for extraterrestrial "life" is to me not that big a deal. I mean even on this planet forms of "life" have been found in the oceans at depths and temperatures that are astounding.

Finding some of that in our own solar system on Mars seems close at hand really.

What we are really looking for is intelligent life, self conscious life, beings somehow recognizable as like us bunch of weirdos.

Roger, good analysis. Can we simplify "The extent of the Universe" by saying that we are coming closer and closer to "seeing" the origin of the "Big Bang" in the Universe, the first stars and the first galaxies, and ergo, there must be at least an equal distance that the Universe expands beyond that point of origin... or is that too simplistic, depending on the geometry of the Universe?

Excellent post, Roger. You may have forgotten one more element in the mix. That is, time. So far, we have existed as a universe cognitive species for only a few thousands of years. It is totally unknown how long a cognitive species survives, on average, before extinction occurs (natural or self induced). The universe is 13 billion years old, more or less, and many civilizations may have come and gone before us. We don't know. Right now we peer into the universe at a tiny, tiny sliver of its lifespan. This adds another dimension (or complication) to the search for extraterrestrial life. Interesting thought, no?

What Roger said is a realistic scenario. Bravo, well said. It does not include opinions or heresy as expressed in the theme statement.

Particularly I object to that statement: "So far, there is no credible evidence of extraterrestrial life."

What about Roswell?

Such statement are equivalent to "Peak oil", "Fossil Fuel" oil originated from Dinosaurs, "CO2 causes Global warming", "war against terror" to add a political statement and many more.

How stupid is the general public supposed to be?

I'm not sure what you mean by "theme statement" but I should indicate that I thought the original blog was well written and pretty much spot on. I just felt it underestimated the numbers.

I meant the original blog when I said 'theme statement'.

Generally I agree with your assessment except for that paragraph starting with the quote that I had paced in italic.

Also, most examples are within our own solar system only. Too narrow in scope I find.

Regards

I wanted to edit and add some but when sending I was out of time.

The original blog looks around our own solar system and is a bit narrow in scope, I find. However, I do not want to be too critical as one has to start looking somewhere.

One planet with Intelligent life in a solar system is likely all one can ask for, and not every solar system can be expected to have a planet with a higher life form.

I forgot what else I had said. The few Minutes given were just too short.

I agree with what you're saying. I think the original post does as well. Ultimately I think we all agree that life and probably intelligent life to a smaller degree is out there and us detecting it is just a matter of time.

Yes, I agree Roger.

I actually think that others have found us already. Making that fact known depends not on them but on our government.

But now I am entering the realm of speculation and better stop talking.

The late Dr. Carl Sagan did the math long ago.

On assumption that the chariates of Gods from extra terrestrials visited earth once long ago, it was clearly concluded that grooming humans is the riskiest deed. It was believed to have sent a universal warning that no one should visit planet earth and engage with humans, just for the reason they are greedy and deadliest. There after no one turned up to planet earth.

Yeah, it could be that, or it could just be that the distances between civilizations are great and the chances of stumbling across one in the vastness of the universe nearly impossible.

Roger Pink,

I would like to make a stir into the discussion now. To me it sounds to have some relevance too. The Bermuda Triangle mysteries had been discussed with a lot of inter connection to extra terrestrial involvement. With the inception of modern technological observation and recording capabilities like NASA and all, there should be some worth data and findings would have developed all these years. Can somebody share their hearing, information and views about?

Perhaps George Bernard Shaw was right when he postulated that earth was actually an interplanetary lunatic asylum?

Nature is so graceful in letting all its resources for consumption of all beings without the slightest resistance. All beings lead a life of present moment. Greediness, possession ,self centered ness and over consumption habits of humans- a strange and rare behaviour totally different from Nature. All human inspiration being inherited from Nature, how these negative values haunt humanity. We are supposed to be a superior and giant visioned species of Nature.

I agree that extraterrestrial life is very likely.

There is a habitable zone around any star: inside too hot outside too cold (for carbon and water based life). Any other forms of life not very likely as Silicon will readily react with water or Oxygen.

There is also a habitable zone inside any Galaxies: the inner region is too often irradiated by massive outbursts of energetic particles and x-rays that will kill any emerging life. This is resulting from Novas, Supernovas, merging Neutron-stars, quakes on Magnetars and likely some more.

The outer boundary is not really sharp: the stars on the outer regions are old stars that are slowly burning (smaller than our sun) so not many Supernovas nearby. To ensure an elemental distribution similar to that we know the interstellar material that was contributing to the formation of our solar system had to go through 2 to 4 Supernovas: only in these the elements above (in the periodic system of elements) Helium are synthesized by Neutron capture.

So it is unlikely that slowly burning old stars have enough heavy elements. And if there are some that have then the resulting life will be very old, much older than ours (by billions of years), so any "civilisation will be likely long extinct at the moment when we are able to observe.

Think about our civilisation, we learned radio-transmission only 100 years ago. Nobody from the years 1910 to 1970 would have been able to listen to our more modern transmissions. So we would not be able to hear what they are talking, we still are not able to think about the emerging possibilities: Tera-hertz transmission, to x-ray modulation may be a big and vast field to investigate, but not to listen if there are signals. Nor we may have the sensitivity nor any ideas what else may be possible.

So the habitable zones will rule out most stars but still very many remain that may have habitable planets: more than 10¹⁰ stars per Galaxy.

The time window is more difficult to resolve: if inside the lifetime of a civilisation there are 100 years that we can hear and understand and this civilisation lasts 1000 years then there may be 10⁹ civilised populations per Galaxy that we can detect in the near future. This is likely an overoptimistic estimate. (Or one star in 1000)

So we may have to search the next 1000 to 10,000 stars to get one hit. But these people will certainly have ultra-sensitive receivers with ultra-low noise, so we won't hear them unless we visit them.

So I don't have any hope that we will have a conclusive information about any alien civilisation within the next 100 years.

If another argument is added: any habitable planet has to have a big moon to stabilise its axis with respect to the plane of circling around the central sun: this will further diminish the number of possible candidates considerably.

And also: any double star or multiple stellar-system is not so likely to give habitable regions around.

Unfortunately! Or fortunately: if they visit us they may treat us as a pest. (Ants, bugs, flees, flies, mosquitoes, wasps, cockroaches and many more are wiped out by "pesticides", think about the possibilities!

RHABE

All your long narration is based on our own experience. I do not agree with it.

What is habitable? Hot and cold you assume are relative to what WE feel.

Oxygen and water is required for life is our opinion. This need not be true.

X rays will kill, is our experience. This need not be true for some other form of life. This other form of life might have emerged as intelligent life.

This is all chauvinism

I object:

this is based on chemistry and speed of reactions being dependent on pressure and temperature.

Other forms of life may be more resistant to x-rays but not very likely as these events may happen once any 1 million years, so no adaption possible or any adaption lost after that time and many generations. If life on earth (on the surface) would have been wiped out any 1 million years there would not be any significant land-life today. And no deep-water tool-using creatures playing with radio-transmission!

Totally other forms of life: very unlikely, no real explanation existing, only scientific fiction.

Not at all Chauvinism, only probability. We know about amino-acids out there, so there is carbon-hydrogen based chemistry, so there will be reactions in warm water.

RHABE

If there is no extra-terrestrial life it would be an enormous waste of space. And nature does not waste anything.

Dragon

Some in this post have raised the issue of inter-stellar travel, which i thought i may add my 2c worth in. We often hear that the distance between potentially life bearing planets is so far that we cannot ever hope to reach there in our, or a crew's lifetime; in this matter i would have to agree.

However it is far more likely that we would be contacted by other intelligent lifeforms, rather than the other way around. Putting time aside, the chance that we will reach a planet with intelligent life is practically nill; however, this is only a restriction of our own anatomy; if we lived for say thousands of years it may be possible for us to reach some of our nearer stars.

Now the chance of knowing which planet to choose for this long journey would be very low, however it is still a chance.

Take into account now, the extensive reaches of our own galaxy. If only a small proportion of planets in our galaxy capable of sustaining life actually have gone looking for other intelligent lifeforms, there is still alot of searching going on.

I believe that due to our lifespans we cannot hope to reach another star capable of supporting life in time to see it. I also believe that if instead of searching for life we make ourselves the search object we will be far more likely to contact these other beings. The question then becomes how do we make ourselves known?

I just came unto this thread, one of the draw backs is one can only see as far as the Light Horizon. The observable universe is only around 13 billion light years away.

p911

Hi,

this horizon includes minimum 10¹¹ galaxies with minimum 10¹¹ stars each.

Very likely some orders of magnitude higher!

So enough playground for evolution to bring up multiple solutions.

RHABE

I do not quite understand the wiki definition but

The age of the Universe is about 13.7 billion years, but due to the expansion of space we are now observing objects that are now considerably farther away than a static 13.7 billion light-years distance. The edge of the observable universe is now located about 46.5 billion light-years awayThe age of the Universe is about 13.7 billion years, but due to the expansion of space we are now observing objects that are now considerably farther away than a static 13.7 billion light-years distance. The edge of the observable universe is now located about 46.5 billion light-years away.

How is 46.5 billion light years away be observable possiible. Is the fabric of space stretched and the light is red shift? Or is wiki not a good source?