What do you mean by “freaks?” Rare, or impossible according to physics? I think you mean the former, but in a universe with trillaguhbillons of planets, you’re going to find two identical snowflakes.
True, but by the same logic there’s a planet somewhere identical to Earth except for the fact that you’re reading this post in German. For the purposes of this thread though, I thought the question wasn’t “is it theoretically possible,” but rather “is it common enough to bother thinking about.”
Lemur866 is making a very important point. People in this thread seem to think that the big leap is from non-life to life - that the big question is whether or not life of any sort can start anywhere else, and if it can that necessarily leads to ET. But we had simple life forms on this planet for 3.5 billion years before we started seeing multi-cellular creatures. And yet life itself started very soon (almost immediately in cosmic terms) after the Earth became even remotely suitable for it.
That suggests that it’s not the existence of life itself that matters, but possibility of it becoming something that can grow in complexity and evolve. There may be simple life all through the universe. If the Panspermia theory is correct, there could even be living life forms (albeit dormant) existing in the gas and dust clouds of interstellar space. But that may not be the important factor.
If it took us 3.5 billion years to get to starting gate of complex life after simple life already existed, it would seem that either that transition takes a very long time, or perhaps that we got very, very lucky. Think about it - if that 3.5 billion years had been 4 billion years instead, we wouldn’t even have complex animals on earth yet.
The timeline looks like this: Earth forms - almost immediately, simple life appears. And there we sit for 3.5 billion years, and suddenly the Cambrian explosion happens, and within another relative blink of an eye suddenly the earth is teeming with complex life forms, and evolution accelerates by orders of magnitude.
This suggests to me that it took some very rare event or some stroke of incredible luck for that change to occur, or that early evolution is very, very slow until you get to some threshold or life develops some features that allow it to expand in complexity.
In any event, the fact that it took billions of years to go from simple life to complex life, in a universe that’s only 12.7 billion years old, might suggest that while life is common, complex life is not. And don’t forget, life couldn’t have started right after the formation of the universe, because we needed stars to go through their lifecyles and create heavy elements before rocky planets could even form.
The early universe was little more than a bunch of very light elements like hydrogen, helium, and lithium. The heavy elements are formed in the interiors of stars and by supernova explosions. So rocky planets may not even have been able to form for 1-3 billion years after the universe formed, and maybe not in quantity for another few billion years after that. So it’s possible that the Earth is one of the earliest generations of planets that could possibly harbor life. Add in the billions of years it seems to take for complex life to spring up, and then the perhaps fantastically long odds of it developing to the point of sentient intelligence, and that might explain your Fermi paradox.
What you are saying is earth won a ridiculously improbably lotto, and that is more likely than not winning a ridiculously improbable lotto?
Well, you also need to take into account the anthropic principle. If evolving complex life is an improbable lotto, and Earth hadn’t won it, we wouldn’t be here to observe that we’d won it.
Aside from the Anthropic principle above, what I’m saying is that complex life at this point in the universe’s history may be rare, and therefore the odds of other planets having intelligent life forms that have high technology are low enough that it’s easily possible that there aren’t any others close enough to us that we could reasonably have detected them.
I’m cool with that. But, hypothesizing we’re in a particular stage of universal life development really isn’t much different from saying there shouldn’t be billions of civilizations at approximately our technological level, right?
Random assertions like that make debate almost impossible, which may be your intention for all I know. We may as well say that physics is a subset of science, and science is a subset of philosophy; therefore, nothing happens in biology that can’t be explained by philosophy. In the interest of cleaning up the mess your assertion makes, the fact is that both biology and physics are subsets of natural science. There are cross-disciplines within the natural sciences, but you made no assertion about any of those.
How do you know what forms life takes? You only have one statistical sample.
I think we must be misunderstanding each other some how. The laws of physics control our universe. Maybe there are things we haven’t figured out yet - and this thread would be a good example - but surely you don’t expect us to discover something that violates the laws of physics?
Life on another planet could certainly be very different from us, but I don’t expect to find anything teleporting or time-traveling or zipping around FTL. Do you?
I don’t even know what you’re talking about, since I haven’t suggested anything remotely like that. Is it possible you’ve confused me with someone else? You seem to be carrying on a number of simultaneous discussions.
Are you kidding? I say biology is controlled by physics, you say that is a “random assertion.”
Please explain.
All he’s saying is that living systems are just incredibly complicated physical systems, and therefore follow the same physical laws as everything else in the Universe. In principle, if you had a powerful enough computer programmed with the physical laws governing the interactions between quarks and leptons, that computer could simulate all of the workings of a cell, or organism, or population of organisms. In practice, of course, organisms are too complicated for that to be practical, so we construct new laws to approximate their behaviour, and we call those laws biology, but it’s still all inherently physics.
It’s random because it had nothing to do with the point I was making. For review, here’s what I said:
But why does that follow? I don’t know how you can avoid an undistributed middle fallacy unless you can show that solar systems like ours will necessarily result in abiogenesis. Maybe the emergence of life had nothing to do with what our planet is like. And maybe the kind of life we know is not at all typical of what life is like elsewhere.
It is okay in physics to state the premise, as Einstein did, that physical laws are everywhere the same. But there is no such law in biology.That isn’t at all a statement about what controls what; it is a statement about the fact that no premise exists in biology that is equivalent to the premise of relativity that physical laws are everywhere the same. Biological laws may NOT be everywhere the same. Conditions necessary for life as we know it on our planet may or may not be the same conditions necessary for life elsewhere. We might not even recognize life elsewhere, as some of the posts on page 1 detail. We might not even have a definition of life that is universally acceptable. See this article, for example: “But what, exactly, is a sign of life? Or more precisely, an unmistakable sign of life? This sounds like a tedious, trivial question, but a quick dip into your high school biology text will show that its not. Defining life in a way thats both complete and exclusive is not only hard, it hasnt been done.” — Seth Shostak, SETI astronomer.
That’s all I’m saying, and has nothing to do with what is a subset of what.
And a cow is a bovine, but so what.
Right. So, in science when someone presents a hypothesis and wants it to be accepted by other scientists what needs to happen? It needs to be testable, reproducible, etc. I guarantee you if someone figures out how to create life in a test tube, they better be able to explain to other scientists how to duplicate the results, and those other scientists better be able to duplicate your results, or something wonky is going on.
Earth is like a test tube, and in a universe with gobblyguhbillons of planets, I fully expect our test to be reproducible, elsewhere. Further, I would assume because we are here, what made us is quite likely the most likely way that things like us get made. Seems like a circular argument, but it’s what we’ve got to work with.
Actually, as I think of it, that’s not applicable either. I don’t think we should call biology a subset of physics just because physical law is often applied thereto anymore than we should call physics a branch of mathematics just because math is often applied thereto. And as I said, there are merged disciplines like biophysics. But not every aspect of biology appeals to physics, like certain taxonomy systems for example (though some do, I know). But in any case, the point he made — however he meant it and whether it holds or not — had nothing to do with the point I made, and thus I called it “random”.
Somehow, I’m not getting through. Nothing you’re saying addresses what I said. What you expect or assume is interesting, but not really important.
Let me try to help by pulling out the root of my post so you can address it directly: “I don’t know how you can avoid an undistributed middle fallacy unless you can show that solar systems like ours will necessarily result in abiogenesis.” That’s the assertion you need to answer.
What you said is,
That’s the point I’m not getting?
I guess I’m going to need you to dumb this down for me, because I’m not getting this disconnect we seem to be experiencing.
What Alpha Centauri scientists consider to be biology would not differ significantly from what we consider biology. The two might be fascinating and strange, but I’m confident they’d break it down to chemistry and molecules and physics, unless you’re proposing they are extra-dimensional magical beings or something.
Oh, okay. and abiogenisis doesn’t rely on physics, whether it’s common or not. I think I’m following you now.