What do we do if SETI is successful?

I cannot imagine any scenario where we're just 100-200 years away from "no more tech" that isn't purely total nuclear destruction. Even then, we'd probably be so close to getting back to a technological civilization that it'd be a blip in the radar at best if we're talking about a society that far away.

We lost 150 years of progress? That's okay, we had 800 more years to advance before the aliens showed up or whatever.

It's such a weird thing I see so many people assuming. We were down to like 16,000 humans on Earth at one point, and that was before we'd developed things that you could theoretically scavenge and jumpstart your tech.

People need to stop doomscrolling; I'm certain this is depression projected.

It was also before we'd burned all the easily accessible fossil fuels.

We mined all of the easily accessible drywall gypsum too, I guess we wouldn't be able to have houses either and would have to live outside in the cold and rain!

Thankfully, unless somehow everything manmade disappears, we'll have scraps of windmills, solar panels, and hydro electric generators - with that laying around, it's easy to eventually figure out the underlying concepts and rebuild them.

With all due respect, I don't think you understand what the "worst case" scenario looks like for global warming, and how close we are to that scenario. For reference, check out figure 1 in this nature article [1].

That has warming by 2300 as 8C in an "emissions continue current trends" path.

Here's chatgpt giving a picture of what 8C warming looks like. Speculative, hallucinations, caveat emptor, etc...but to give a sense of proportion this, last time the earth was 8C *cooler* than now, ice covered 25% of the planet:

> At +8°C, Earth is fundamentally transformed. Large parts of today’s populated zones—South Asia, the Middle East, Africa, southern Europe, the southern U.S.—are functionally uninhabitable for humans outdoors. Wet-bulb temperatures regularly exceed survivable limits. Agriculture collapses across the subtropics; even mechanized, climate-controlled farming is marginal. Most of the world’s food comes from high-latitude regions: a narrow band across northern Canada, Scandinavia, and Siberia. Sea levels are dozens of meters higher, drowning coastal megacities; Miami, New York, Shanghai, and London are gone. Phoenix is lifeless desert. Seattle is coastal tundra, wetter but still survivable.

> Civilization persists only in fragments. Mass migration and resource wars have rewritten borders. Population is a fraction of 21st-century levels. Global trade, universities, and modern governance are mostly memories. Local, self-sufficient polities dominate. The United States as an institution likely dissolves or transforms beyond recognition—2 out of 10 chance of recognizable survival. Harvard or MIT survive, if at all, as digital archives or autonomous AI-driven knowledge systems—3 out of 10. The world would still have people and culture, but not civilization as we know it.

Edit: I would appreciate knowing why I'm getting downvoted when I added citations for *possible* warming paths (from nature!). Yes, the chatgpt explanation is speculative but I mean, look at the thread we're discussing.

[1]: https://www.nature.com/articles/s41612-020-0121-5

In Carl Sagan's Cosmos, he talks about how many advanced civilizations could be out there capable of radio astronomy, and how as in our own experience, we have the capability to wipe out own civilization, so that would also be a factor in other advanced civilizations and could act as a limiting factor. There are many such factors other than nuclear destruction that could impact all functioning of an advanced society, rendering it nonviable.

The idea has nothing to do with "doom scrolling". Go watch some Cosmos...

https://www.youtube.com/watch?v=qsl9f83P0Ys

Electrification of transportation is already well underway. Obviously ships and planes will lag behind, and may even be forced to use biofuels if we run out of fossil fuels, but the idea that the world will stop when we run out is outdated.

Green power generation is also making huge strides forward, and battery technology is improving enough to make fully green grids a reality. We already see articles about how some countries are managing to go entire days without burning any fossil fuels for power generation. This will increase over time despite what the doomsayers predict. We aren't there yet, but the progress is almost inevitable.

The bigger problem is that we've already burned so much fossil fuel that we are noticeably altering the climate. This is going to cause a lot of stresses in the future, especially in a post-collapse scenario.

Perhaps the aliens will share advanced technology with us such as how to build a tent.

When we have a nuclear destruction, and some of us survive, then we will have a problem which we cannot solve easily even today: absolute annihilation of the ozone layer. It won’t be a soft reset at all. If the ozone layer disappeared right now, its consequences would be absolutely catastrophic even with the current civilization completely intact.

I can't wait until everyone realizes how easy it is to rebuild Göbekli Tepe with hand tools.

They’re going days without burning fossil fuels by using high tech solar panels and windmills and such. What happens when they stop being made and they eventually break down? You’ll have to bootstrap tech again but without low-tech sources of concentrated energy. Electrified transport is great today, useless two hundred years ago.

There are lots of other building materials available. What other sources of energy are there which are suitable for driving a new industrial revolution if you’re starting over? Wind and solar aren’t worth too much without high tech to enable them. Biomass is insufficient. Nuclear needs high tech. Hydro could do, but it’s pretty limiting.

I appreciated your comment. I’ll also note that the path to that future will not be fun - you/chatgpt describe a kind of end state 275 years away, but things will evolve to that state over time. I suspect the downvotes may reflect people’s desire not to face the likely reality.

It'll recover even after a nuclear war, but it'll take time. But the impact on Earth in terms of resources will also be significantly lower during those 200-300 years it takes to rebuild.

The population will be very small, but being very focused and hopefully able to jump start civilization again based on all the materials and knowledge still available.

Part of the problem of getting +/- 8C of different global temperature is the speed of it. https://xkcd.com/1732/ shows a timeline that goes back to 20000 AC, where global average temperature was like 5ºC less. There has been changes, but also adaptation. Now in less than 200 years we increased 2ºC, and the speed of change has increased, it was around 10 years ago when we reached 1ºC over preindustrial times, and now we are at 1.5ºC.

And without adaptation you get mass extinction. And the human system may be pretty fragile against the disappearance or deep change of key components of the global system.

Of course it's related to your doom scrolling-provided depression. You think every single civilization is going to wipe itself out? You think most will? You think half will? Why, because humans are mean?

I've seen Cosmos. It's not a counter to this argument in any way.

Solar panels are somewhat high tech, but wind turbines are 17th century technology. The electric motor you need to attach to turn it into a generator is also pretty low tech. You can even use lead acid batteries to even out the power delivery, and those can be incredibly low tech and also highly recyclable.

Obviously you're not going to get to 100% in a week if you're rebuilding civilization from the ground up, but if you can retain some of the knowledge you can get a big step up and hopefully avoid some of the pitfalls that caused the downfall of society in the first place.

Insufficient for a hydrocarbon sugar high, but hardly insufficient for bootstrapping a civilization. Yeah, bio and hydro are limiting. So we would deal with the limits for longer until we worked our way past them. It's wildly condescending to imagine that this would be a show-stopper, doubly so when you review the history of all the things that were historically not stopped by the lack of fossil fuels.