It's a common view that extraterrestrial life is probably pretty common... but higher life forms, including intelligent life forms are probably pretty rare.
Life has existed on earth for about 3.8 billion years. Intelligent life -- assuming that we are the most intelligent species on this planet -- has only been around for a few hundred thousand years. And we're likely going to be extinct within a few centuries, probably at our own hand. Even if we survive longer, a natural disaster is likely to finish us if we don't get off this planet. As percentage of total time in the history of this world, that's just 0.002 %.
There may be millions and millions of worlds with intelligent life, but they flicker into existence and die out before a new one comes along in that part of the universe. The vast timescales and distances mean that these civilizations will never encounter each other.
Then you get into the whole question of: What is intelligence? We tend to define it in terms of our own psychology, but now we're coming to realize that intelligence can be defined in many ways. Corvids, primates, octopii, marine mammals... we've come to define all of them as intelligent in some ways. But how many of them have an understanding of the broader physical universe?
Similarly, on some alien world, the intelligent lifeform may be some sort of moss growing on rocks, some sort of fish swimming in a chemical ocean, the lighter-than-air jellyfish gas bags floating along in the atmosphere... They may have no concept of space, or even care about it, if they do. We could literally land on the planet and walk among them and not recognize them for what they are.
So, I think we'll find primitive life within our very own solar system, but I doubt we'll ever encounter the aliens of science fiction and The X-Files.
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Sandman3 (1453)
6 years ago
WOW. What a great thread and intelligent answers. Don't see that to often on message boards.
That being said in our lifetimes I highly doubt we will find anything. And as someone said I don't think the human race will survive long enough to find anything.
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[deleted]
6 years ago
It's humbling... even a little depressing... to dwell on the question. For example, we've only developed the means to broadcast our presence in the last century. The sphere of our expanding signals has only passed about 512 stars in total... compared to 200 BILLION in just our galaxy. That doesn't even register as a percentage it's so small.
Subtract the stars that for various reasons wouldn't be home to compatible planets, and it would be incredible indeed if any other civilizations existed out there and detected us. After a few centuries, our signals would be dispersed among 260000 stars... still only a FRACTION OF A PERCENT of all the stars in our galaxy.
And, what if these signals were passing dozens of planets with civilizations... except that they are living in the equivalent of our Middle Ages? Neither of us would know about the other, and we could be gone by the time they become mature enough to announce their own presence to the cosmos.
Or go the reverse route... a civilization that is so far beyond ours in its knowledge and technology that they can't even be bothered trying to communicate with us. They are trying to find other ancient civilizations like their own with signals that are passing over us/through us/around us, and we are completely oblivious to them.
I think the coolest/scariest/most awe-inspiring thing that could happen to mankind is to land on Mars... and discover one single ancient alien artifact. No explanation, no plaque, no 2001-style beacon... just a simple artifact that tells us that someone sometime in the past paid us a visit.
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MIchiganJFrogg (-35)
6 years ago
[deleted]
[deleted]
6 years ago
By primitive life, I'm talking VERY primitive... like virus-level primitive, maybe -- if we're lucky -- single-cell stuff.
Life here on Earth exists within some extreme temperature and environmental variations and there's no reason to expect otherwise elsewhere in our solar system. And, you inadvertently qualified your statement with 'life *as we know it* -- life elsewhere will have evolved in very different chemistries than life here on earth. Indeed, when life first started on earth, it was effectively an alien world with a very different atmosphere and temperatures.
Most exo-biologists are pretty confident we'll find something within our own solar system.
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