grindy

I hope you're joking.

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A smell of petroleum prevails throughout.

William_the_Bloody

Is there life on Mars? There is now....well potentially

Mars Curiosity rover may have transported Earth bacteria to Mars

Trollheart

Why?

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Trollheart: Signature-free since April 2018

The Batlord

You believe in alien abductions?

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John Wilkes Booth

because they can all be wrong.

Guybrush

I believe there's lots of life out there and a very rare bit of it will be what we roughly think of as intelligent.

Similar conditions and processes that gave rise to life on earth could happen elsewhere on a multitude of worlds - and likely have. Even extra terrestrial life elsewhere in our own solar system seems like a reasonable possibility to me, for example on Europa. We have vent ecosystems on planet earth that get their energy from heat and chemicals vented from our planet rather than the sun. Similar ecosystems could exist under the surface of otherwise inhospitable worlds.

We haven't seen a lot of planets. We've detected a lot of planets. Generally, they are detected by watching stars. When a planet passes between our telescope and the star we are looking at, there is a change in the luminosity of that star. The bigger the planet, the bigger the change. Hence, this method is best for finding really big planets and not small, rocky, earth-like ones. And when a planet is detected this way, it doesn't mean we've gotten a look at it and could possibly see if it contains trees or cities.

Winning the lottery is an improbable event, but there are still plenty of lottery winners. Even if the lottery was a million times harder to win, there would still be winners - even if they'd be a few years apart.

Life elsewhere in the universe has a lot of chances.

Imagine that we are the product of one lineage of life that stretches back all the way to some origin of life (if hard to pinpoint). If that origin hadn't happened or life had completely died out some millions of years later, we wouldn't have been here. But maybe life would have redeveloped in a new lineage or maybe the 30th attempt would have been the successful one. This planet could have animals on it or be inhabited only by unicellular organisms or whatever. It might not be humans, but it would likely be something.

I think a likely problem with intelligent life is that it probably tends to eradicate itself by using up and destroying resources and then crashing. Maybe intelligent civilizations only tend to last a short while.

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Trollheart

If you believe in the possibility of extraterrestrial life, then why could they not have visited this planet? I'm not a UFO nut, I don't necessarily believe abductions happen, but I'm not arrogant enough to state they categorically did not. They could have, is what I'm saying. And a lot of the stories abductees tell are remarkably similar. Didn't any of you watch The X-Files?

Is it more stupid to believe in the possibility of life on other worlds (which then allows they may have visited ours) than to put your faith in a concept with no empirical evidence to back it up at all, to believe in a god? I'm not saying there's anything wrong with believing in God or a god, but it's just as much a leap of faith as allowing the chance that some --- probably not all, or even that many, but some --- of these abductees may in fact be recalling actual experiences. I don't know for sure they did, but by the same token you don't know for sure that they didn't, so you have to be open to the possibility.

"You know what, Vort The Invincible? Sometimes I look up at the sky and I wonder ... could there be other intelligent life out there?"

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Trollheart: Signature-free since April 2018

Guybrush

I believe in life on other planets, but I don't think we've been visited by representatives of other intelligent civilizations. The greatest barriers are space and time and these barriers are generally enormous. Aliens would probably have to cross oceans of time and space to travel from their planet of origin to ours and I just generally believe that it's too big an obstacle. Even if it's not impossible, it is likely to be impractical and so if there are civilizations that colonize space, it doesn't necessarily mean they would travel very far in cosmological terms. If it takes you 50 000 years to get to one planet and 500 years to get to another, the choice seems simple. Still, colonizing space would make a civilization more resistant to dying out and they could radiate out over time, but still ..

There's also a lack of evidence that we've ever been visited. I imagine the only real point of visiting our planet would be because it holds some resource they could use, even if it was just something simple like decent gravity, water and a good temperature. When we look to other planets, we think of whether it's a place we could colonize or perhaps harvest something from .. I assume intelligent aliens would have the same practical sensibilities.

If intelligent aliens had visited earth in the past, for example when the dinosaurs were around, I would think they'd build a colony - perhaps bring some alien organisms for agriculture or whatever. There'd be some indication they were here, like a very different lineage of organisms that suddenly seemed to appear in evolutionary history or perhaps even ruins of an ancient civilization.

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Xurtio

Since the 1980's, the way planets are detected is through doppler spectroscopy. High-dispersion spectroscopy is what they are starting to use to detect whether planets have a chemical composition complex enough to support life or not.

Either way, I won't get my hopes up until there's solid evidence.

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H̓̇̅̉yͤ͏mͬ͂ͧn͑̽̽̌ͪ̑͐͟o̴͊̈́͑̇m͛͌̓ͦ̑aͫ̽ͤ̇n̅̎͐̒ͫ͐c̆ͯͫ̋ ̔̃́eͯ͒rͬͬ̄҉

Guybrush

This is basically what I mentioned, but knowing a planet's chemical composition generally does not tell us if there's life on it. And also as I mentioned, the greater the mass of a planet, the easier it is to detect this way and so as a method, it favours detection of big planets which tend to be inhospitable gas giants.

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