JFK-1
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There must be someone around here who has an interest in general science aside from the current virus dilemma so let's try to get a little discussion going. To kick it off I will ask a question I saw recently on another forum. The title of that topic was "We are not alone.... Maybe"
They were contemplating intelligent alien life and whether it's visiting the earth. My own opinion is there may be intelligent alien life with a high likelihood if we consider the universe as a whole. But visiting the earth no chance. I will copy/paste the post I made on the topic.
They were contemplating intelligent alien life and whether it's visiting the earth. My own opinion is there may be intelligent alien life with a high likelihood if we consider the universe as a whole. But visiting the earth no chance. I will copy/paste the post I made on the topic.
When I was growing up there were an estimated 50 billion galaxies. The most recent estimate is two trillion galaxies and since the number has always grown as better telescopes come online I expect it to continue to grow.
The Milky Way, not a large galaxy by any standards, contains between 100 and 400 billion stars. It's difficult to judge the number accurately in part because we're trying to look at it from the inside.
But let's call it the median 200 billion and consider that a galactic average throughout the universe. So now we're looking at 2 trillion times 200 billion stars. And when you consider there are a lot more planets and moons than that the numbers are staggering. Incomprehensible.
It's suspected that life on Earth began relatively soon after the formation period when the planet had settled and cooled off. And in fact it's further suspected that it probably occurred more than once. It's thought that the first instances would have been wiped out during a heavy bombardment period as the solar system planets cleared their orbits of remaining proto-planetary debris.
This involved collisions in which some potential planets would have been destroyed. It's thought just such a collision between the Earth and a Mars sized object created our moon. And it's further thought these collisions are also the reason that while most asteroids and meteorites are rocky some are largely iron based. These much rarer iron based meteorites are the debris of an iron core which formed at the centre of a planet sized object which was then destroyed by a massive collision.
The bombardment/collision period involved some very large objects some of them hundreds of miles in diameter and even moon or planet sized. An impact from an object a few hundred miles in diameter would reset the planet. The entire surface down to a considerable depth would be molten in the aftermath which would effectively sterilise it.
If this suspicion that life began on multiple occasions is correct then since the ingredients of life are everywhere out there we would have to further suspect that it's probably relatively common on a suitable planet within the 'Goldilocks zone' of a suitable star. Not too far away to be frozen not too close to be fried.
My own suspicion is that given the numbers mentioned above it would be astonishing if there were no other life in the Milky Way far less the universe. And i'm talking about life on any scale such as even bacteria. Just has to be out there in my view.
Then there's intelligent life which is a whole other matter. The Earth is estimated to be around 4.5 billion years old and while it's thought life began relatively quickly it took almost all of that time for intelligent life capable of human level technology to appear.
Humans are pretty much brand new on a geological time scale and weren't guaranteed to make it even after the advent of high intelligence.
There's an idea called the Toba catastrophe theory suggesting that a bottleneck of human population occurred around 70,000 years ago proposing that the human population was reduced to perhaps as little as 10,000 individuals. That's verging close to extinction but luckily we made it.
The bottleneck has been linked to the Toba supervolcano in Indonesia which erupted triggering an environmental catastrophe that could have been the end of us.
So with all that in mind my suspicion is that life may be relatively common but high intelligence much rarer. But then again with the staggering numbers involved I don't think for a moment that humans are unique in that respect. Even if it were a billion to one chance we could still be looking at potentially hundreds of intelligent civilisations in the Milky way alone.
But as for the question of alien visitations to the Earth I don't believe for a moment that has ever happened. A further problem with the proposition of intelligent life is that there's every chance intelligent civilisations have come and gone many times in the lifetime of the Milky Way which is estimated to be one of the older galaxies at around 13 billion years.
I feel that the chances of two intelligent cvilisations existing in the Milky Way at the same time and actually finding each other have to be extremely remote. Even if it happened that two such civilisations did occur at the same time and somehow found each other any contact would be infinitely more likely to be by some form of radio communication.
The distances involved make it highly unlikely that any civilisation would waste resources on a journey that could consume the lifetimes of multiple generations. Entire colonies would have to dispatched in enormous ships containing hundreds or even thousands of beings most of whom would never live to see the journeys end.
There are no aliens visiting the Earth and there are unlikely to ever be any. I think it's telling that since the world became smothered in cameras on phones UFO reports have actually declined not increased.
Something like 'miracles' no less. When there was no way to record it miracles were happening all the time. Now that there is a way to record it we have zero evidence of miracles. UFO's and visiting aliens are likely in the same category. Wishful thinking.