Pinball1970
Valued Senior Member
You said,None of that is a requirement for life or 'civilization'. One could as easily argue that life managed to evolve despite these instabilities, and it is stability after all that tends to favor life, especially advanced life. We barely made it here on Earth, evolving civilization only near the end of our window. Took 5 billion years to get here from the earliest life, and yet in another billion it seems conditions here will not support multicellular life at all. That's cutting things pretty close.
Size matters little if at all. Water (and carbon) is wonderful for our kind of life, hence the need for a 'habitable zone', but that seems common enough that there is at least one other planet with liquid water on it just in our solar system. Avoiding asteroids is part of the stability thing.
Here I have my doubts, since the center of a galaxy, especially early on, tends towards very unstable conditions. Sure, life might take hold on some planet in a habitable zone, but with so many rocks to wipe things out, and so many large objects (passing stars and such) to disrupt stable orbits, planets simply are not likely to stay habitable for any length of time. It's way out here in the boondocks that stability is to be found, and more likely with a smaller star with a far longer lifetime than that of our sun.
Let's suppose that we would notice, that we could detect a civilization by looking for radiation that would not otherwise be emitted, so we could say see them even in Andromeda if they were there. What are the odds that a civilization would be thus detected?
Nobody has mentioned the 'great filter', which is a frequent solution to the Fermi paradox. It says that a civilization like ours is fleeting, and pretty much ends when the non-renewable resources run out, or until we wipe each other out. Either way it happens in an amazingly short time, so not only do we have to look in the right direction to see them, but we have to look at exactly the right time, and the odds of doing that are pretty much nil.
Here's a picture of the universe:
We are at the 'here and now' point. Put this picture (a nice poster size one) on a wall. Throw a dart at it. That's the alien civilization. If the dart doesn't land exactly on the red line, we cannot see it. Only an enduring civilization would have a significantly extended worldline long enough to possibly cross the red line, and it appears that such enduring civilizations (certainly not our own) are exceedingly improbable. That's a good reason we don't see them. The dart throws are simply not on that red line, and we only see stuff that is.
"None of that is a requirement for life or 'civilization'. One could as easily argue that life managed to evolve despite these instabilities, and it is stability after all that tends to favor life, especially advanced life."
This is speculation, take away the moon, it's gravitational effects, tides and tilt and we could have had a very different planet not necessarily favouring our evolution.
"We barely made it here on Earth"
No Idea what you mean by this or "we."
Homo sapiens? Seven billion individuals is hardly "barely making it."
" evolving civilization only near the end of our window. "
What window? We have been around for about 100,000 years or so that is no time at all geologically speaking.
"Took 5 billion years to get here from the earliest life, and yet in another billion it seems conditions here will not support multicellular life at all. That's cutting things pretty close."
Yes and no. Life evolved on earth after about a billion years, after the formation of the earth at least once, a few billion years of single cells then multicellular about 400 million years ago.
The timing from there to vertebrates, mammals to primates and us seems long winded. Perhaps we would not be here at if it was not for the KT?
"We are at the 'here and now' point. Put this picture (a nice poster size one) on a wall. Throw a dart at it. That's the alien civilization. If the dart doesn't land exactly on the red line, we cannot see it. Only an enduring civilization would have a significantly extended worldline long enough to possibly cross the red line, and it appears that such enduring civilizations (certainly not our own) are exceedingly improbable. That's a good reason we don't see them. The dart throws are simply not on that red line, and we only see stuff that is."
Another illustration is the spherical area covered by our current (and past) technology in terms of EM waves transmitted. A tiny area of our own galaxy which itself is 100,000 light years across.
Our EM waves have reached 100 light years out?
We can "see" distant stars and galaxies of course but only as they were in the past.
That was the point of my UAP posts, what are the chances both civilizations evolve, survive together and are close enough.
Last edited by a moderator: