@David1955 the natural order of things is that nature will expectorate any species that does not adapt. That is the basis of evolution. It does not happen overnight. But it will happen.

@David1955
Don't forget that no species exists in a vacuum. Extinction of one ir a few keystone species may lead to ecological collapse and mass extinction. And species like ours, at or near the top if the food web, are in the most precarious position of all. Knock out enough species below us, and we go too. Some species may survive, but they are likely to be ones that have far simpler needs.

@David1955
I was talking about only one planet (ours). But what happens here can happen elsewhere. Isn't that a useful assumption when working out potential solutions to the Drake equation? And what we see here (admitting that the end of the story is not yet written) is that people do not en masse abandon religion, do not
embrace science and reason, and do not
pursue social and economic justice. So it may not be unreasonable to think that the universe is full if dead civilizations. This one is only a few hundred years old and appears headed for a cliff. But who knows? Maybe those others were/are populated by beings that were/are better than us.

@David1955
Yes it us an interesting idea.

"It is ridiculous to assume we are it. That would be an unimaginable waste of space."

The universe doesn't care about wasted space ... it actually seems to embrace it, if you look closely enough.

@Sticks48 Silly and arrogant are human constructs. The universe cares not one whit about arrogant or silly.

Show me another life form not from earth, then I'll believe we are not alone.

My hypothesis that we are the only life in this galaxy will still be correct for many hundreds, if not thousands of years from now. Yours? Unproven for just as long.

And before you spout "lack of evidence is not evidence of lack", a hypothesis with no proof is just one of many different ideas which may or not be true. I can point to hundreds of planets we have discovered that can't harbor life as my proof that we are alone here. Earth is an anomaly; and we are going to kill it.

I agree that the probability of ours being the only planet with life on it is vanishingly small. But until we have proof, we simply cannot say for sure one way or the other. However, I think it is reasonable to operate under the assumption that there is extraterrestrial life. We just need to remember that this is only a working assumption. Thus we protect and maintain our only reliable pathway to enlightenment: the scientific method.

I was listening to a talk by Krauss and Dawkins and they said that there is probably life on Enceladus. Apparently, they have determined that the outer ring of Saturn is made of ice from this world and there is organic matter there. So this world has an ocean that has organic matter within it. They will have to go there to check for sure but there is a good chance of this.

@dalefvictor I have read this to.

maybe some of them go directly to photosynthesis for an energy production, eschewing fossil fuels and nuclear?

If you follow the link in the article to the actual study you'll find a pdf download of the source paper. An abundance of details, formulae, conclusions etc. More than this particular TI is able to fully comprehend

@Salo Thank you, will do.

@David1955 I love your last sentence! Please forgive me if I steal it on occasion