Why do scientists claim the universe is teeming with life but haven’t found a single instance of it?
The odds are life is abundant but the nearest star is 4.5 light years away. A bit far to detect life with our current state of science.
I’m sure some scientists do make this claim. However, do you have any evidence that this is the consensus view amongst astrophysicists and/or exoplanetary researchers? I have my doubts that it is.
Which scientists are claiming this? I’m a biologist, and it’s certainly not the prevailing view. The prevailing view is that we don’t know yet, obviously, because we have almost no data.
And we HAVE found a single instance of it - Earth. That’s just it. It’s only a single instance. Any scientist knows you can’t draw large conclusions from such a small data set.
Most scientists don’t claim it as fact. But it’s a strong possibility, simply because the universe is so big and it’s unlikely that something has happened exactly ONCE in this entire universe. Also, in recent years we have discovered hundreds of extrasolar planets, which shows that planets aren’t exactly rare. Just by extrapolation, we know there are billions of planets just in this galaxy.
As for why we haven’t found any non-earth life forms, it’s because we haven’t explored very far at all. Humans have only been to the moon, and no further. We’ve sent a handful of probes to Mars and a couple to Venus, and done remote observations (images and spectroscopic analyses) of other planets and moons in our solar system, but that’s about it. There could be life under the ice of Europa or deep underground on Mars and we wouldn’t necessarily know it. As for extrasolar planets, we can’t even take a picture of even the closest ones, let alone do a spectroscopic analysis to look for signatures of life.
Have you ever heard of the “Drake equation”? It’s a sequence of factors that when combined (i.e. multiplied together) tell you how many alien civilizations in our galaxy with whom we might eventually communicate.
Unfortunately, the value of most of those factors is completely unknown though there’ve been several guesstimates over the years. The BBC has an interesting article on it at Drake equation: How many alien civilizations exist? - BBC Future
The main scientific argument is that there’s really nothing all that special about the chemical composition of Earth or it’s astronomical location. There are countless planets out there that are probably just like Earth.
The main crux of the matter is still: How did life begin? We don’t quite know, but we do know a lot. And we know that the simple chemicals available on any Earth-like planet will probably lead to life over time. PROBABLY.
Once all the steps of abiogenesis have been worked out, there won’t be ANY doubt about how many planets may contain life. In fact, we will probably be able to state with great certainty that any particular planet that we know enough about either has life or doesn’t. (Life as defined by Earth standards)
It is entirely possible of course that life might exist outside of Earth-like conditions, and that only makes it even more likely that the universe is “teeming” with life. (I don’t like the use of that word because the Universe is vastly empty but if you just mean there’s a lot more than just one planet with life on it, then go ahead and use teeming)
It’s a strong possibility that they have found one instance… on a planet around the nearest star, the planet with the big moon…
It’s the second instance that’s lacking.