Quoted from benheck:

The universe was spinning 8 billion years before our planet even formed. We went from hunter-gatherers to visiting Pluto in just tens of thousands of years. 99% of mankind's technology has been created in just the last few hundred years.
Imagine what a civilization could achieve with even a 100,000 years head start on us. Then consider they could have BILLIONS of years head start.
I think the opinion that no civilization could last that long without destroying themselves is close minded. That's assuming a closed system. Easter Island is a good example of this. So is a planet.
But if we could travel the stars such problems as politics, famine, war would be inconsequential. Also spreading your race across worlds would increase your chance of survival not limit it. Pretty much all our issues stem from resources. Space travel, hell even mining asteroids would solve a lot of that. Imagine claiming not just a continent but entire planets.
Worrying about light speed is also naive. We don't even know how our own universe works. We didn't know how electricity worked 300 years ago. There could be means of travel we can't even conceive of yet. Spooky entanglement is totally a thing. How does it work? Could these underlying substructures to space time be exploited?
To say space travel is limited to what we can achieve with our current combustion based propulsion methods is like Ben Franklin getting zapped by a battery and assuming it could never be harnessed into a super computer.

Quoted from CLEllison:

that is the thing no one can agree upon.

Quoted from robertmee:

If you make the snow globe airtight again, it would extinguish the fire. But we arent an airtight snow globe. Not even close. We have these things called plants that synthesize co2 into oxygen. That's science.

Quoted from robertmee:

Except for the pesky fact that the earth is getting greener
https://www.google.com/amp/s/amp.iflscience.com/environment/despite-decades-deforestation-earth-getting-greener/

Quoted from mof:

I am not an astrophysicist, nor do I play one on TV... Just trying to use my brain a little for fun.
I prefer to start as a non-believer in an idea, and then try and keep an open mind and consider as many angles as possible to consider likelihoods. I have no idea if aliens exist. I think it's likely they are out there somewhere, given how many planets we've found just recently, and how big the universe is (and continues to get measured as much bigger). But I CAN take a few guesses for fun, about whether we would ever likely encounter any aliens.
In order to avoid human species "projection" and in order to take a few guesses towards what a "super advanced" civilization might have for "needs", I will use extrapolation to move far away from our "early-stage, smart-talking-animal" condition -- and move closer to "evolution-infinity", or "god mode" i.e. (in spirit mode without need for physical items/objects) as I consider a few examples.
Assertions:
1. As a civilization's tech approaches infinity (god mode), the need to have to travel and find precious resources goes down (at some point, you can make them yourself, from whatever resources you have, or you simply no longer need them)
2. As a civilization's tech approaches infinity (god mode), the need to travel and explore goes down (once you can leave the body, you don't need physical resources)
So with those two assertions in mind, I'm going to guess that for an alien civilization that reaches us in a ship, (which requires near-light-speed travel, or a refined ability to hibernate) -- they would have to be in a "tiny window of evolution" just a few 1000 years ahead of ours to: 1. accomplish near-light-speed travel or long-term hibernation AND 2. still have a need for physical resources OR 3. have an ethical need to help other civilizations
But the universes show us that the RANGE of AGE and SIZE of all the objects in the universe is SUPER BIG, and thus the range of civilizations might be so as well -- a BIG range. Why do we so quickly consider that aliens would be just a few ticks up the evolutionary scale from us considering the range of possibilities?
For the REST of the aliens in the far out future -- way out there who are 100,000's of years ahead of us, and are nearing an age of "god-mode" -- they won't "need" to reach us. And if they did need to help us out, wouldn't they do it in a more un-detected (without ships) fashion?
So I'm going to go with the "odds" of someone reaching us, AND being hostile are VERY LOW... and I'm gonna go with the odds of them being WAYYY more advanced, AND being detectable AND just curious or helpful, is LOW as well.
Possible? Sure anything's possible... but I'm still skeptical that in our TINY little window of existence here on the possible evolution map over billions of years, we are likely to see OTHER beings come in bodies AND in ships to us (to explore, help out, or take from us)...
I'm also going with SUPER low odds that we'll detect with our 5+ senses physical objects/beings similar to us, AND only slightly more advanced than us, having our corporal needs...
And don't even get me started on the chances of us understanding their form of communication <.00000000001 % -- Sure they may understand us to a degree -- but that's not communication.
All our sci-fi books and movie scripts are relatable "projections" to warn us about ourselves in the future. They are not likely events.
-mof
I'm totally open to new ideas on this tomorrow. Just having fun here... Enjoy the coffee talk.

Quoted from Orko:

I want to see the inter-dimensional elves. Where do I sign up?