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Once we can see them, it’s too late

scottaaronson.com

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Re: Once we can see them, it’s too late

#31

Post by piker »

Huh?

> Only when the sphere’s thin outer shell had reached the earth—perhaps carrying radio signals from the extraterrestrials’ early history, before their rapid expansion started. By that point, though, the expanding sphere itself would be nearly upon us!

Wouldn't the problematic portion of the sphere be, by definition, millions of years away from us? Given that radio waves travel at the speed of light, and the alien civilization travels at slightly less than the speed of light, it seems like we should have at least however many million years it took for those aliens to get from producing radio waves to "maxing out" travel.

Re: Once we can see them, it’s too late

#32

Post by btilly »

isoprophlex wrote: post #3

This is the most profound thing I've read in a while. I'm tempted to whip up some numerical simulation to verify this to some extent... > But here’s the interesting part: conditioned on all the steps having succeeded, we should find ourselves near the end of the useful lifetime of our planet’s star—simply because the more time is available on a given planet, the better the odds there. I.e., look around the universe a…

Want something scary?

The form of reasoning used is exactly that in the https://en.wikipedia.org/wiki/Doomsday_argument for why humanity is unlikely to last long, and almost certainly will not have a future where we break out and colonize most of the Solar System, let alone the stars.

If you believe both arguments, the most likely outcome is that there is one more step on the way to Robin's argument. And that outcome is the replacement of biological intelligence with mechanical. So indeed we give rise to an expanding wave of technological civilization. But we are close to peak population and will not ourselves see that civilization.

All hail our future AI overlords!

Re: Once we can see them, it’s too late

#33

Post by ctdonath »

ivalm wrote: post #18

This kind of assumes that a “maxed out” civilization can expand at speed of light, but I don’t think it is given. It may very well be that meaningfully massive transport cannot exceed even a small fraction of c . After all, propulsion has to make energetic sense. 1. There is energy to get to speed 2. Mass of fuel to decelerate (and you have to accelerate that fuel in the beginning!) 3. Highly blue shifted CMB (that a…

3D printing.

Deliver the printer, rest is just information.

Re: Once we can see them, it’s too late

#34

Post by larsiusprime »

jstanley wrote: post #27
larsiusprime wrote: post #5

This seems like a variant of a hypothesis I've heard before: "The universe is old enough, and the rate of expansion of a spacefaring civilization is fast enough (relative to the age of the universe, even at sub-light speeds) that either the aliens should already be here since long ago, or we're the first (or among the first)." ?

What makes you think we'll be among the first? No human being has ever set foot on a different planet. No man-made object has ever reached a star system outside our own, let alone landed on a planet. We may still be quite a long way away from accomplishing those things at scale.

I'm just asking if the article is making a similar argument to the stated hypothesis.

Re: Once we can see them, it’s too late

#35

Post by xvedejas »

ivalm wrote: post #18

This kind of assumes that a “maxed out” civilization can expand at speed of light, but I don’t think it is given. It may very well be that meaningfully massive transport cannot exceed even a small fraction of c . After all, propulsion has to make energetic sense. 1. There is energy to get to speed 2. Mass of fuel to decelerate (and you have to accelerate that fuel in the beginning!) 3. Highly blue shifted CMB (that a…

I understood the "close to the speed of light" really meant something much much smaller than 0.1c, since on cosmological timescales the difference between the first radio signals and domination from an alien civilization could be millions of years, and that'd still be an instant compared to the time before and after the event. So I'm assuming for the fermi paradox to work out here, we'd not need speeds anywhere near 0.1c

Re: Once we can see them, it’s too late

#36

Post by ivalm »

ctdonath wrote: post #33
ivalm wrote: post #18

This kind of assumes that a “maxed out” civilization can expand at speed of light, but I don’t think it is given. It may very well be that meaningfully massive transport cannot exceed even a small fraction of c . After all, propulsion has to make energetic sense. 1. There is energy to get to speed 2. Mass of fuel to decelerate (and you have to accelerate that fuel in the beginning!) 3. Highly blue shifted CMB (that a…

3D printing. Deliver the printer, rest is just information.

Sure, but printers have mass/volume and require energy. I think in all Van Neumann probe scenarios (which this is) the fact that you bring a micro—replicator that makes other micro-replicators is a given.

Re: Once we can see them, it’s too late

#37

Post by ivalm »

xvedejas wrote: post #35
ivalm wrote: post #18

This kind of assumes that a “maxed out” civilization can expand at speed of light, but I don’t think it is given. It may very well be that meaningfully massive transport cannot exceed even a small fraction of c . After all, propulsion has to make energetic sense. 1. There is energy to get to speed 2. Mass of fuel to decelerate (and you have to accelerate that fuel in the beginning!) 3. Highly blue shifted CMB (that a…

I understood the "close to the speed of light" really meant something much much smaller than 0.1c, since on cosmological timescales the difference between the first radio signals and domination from an alien civilization could be millions of years, and that'd still be an instant compared to the time before and after the event. So I'm assuming for the fermi paradox to work out here, we'd not need speeds anywhere near…

If you move slower than 0.1c then you can’t really cross between galaxies (or at least you are limited to very nearby ones). So we only have to worry about grabby aliens in our galaxy AND we can be fairly certain that there are currently none! Since we ourselves are probably only thousands of years from being grabby this implies we don’t have advanced competitors .This is a very different picture from what Hansen discusses.

Re: Once we can see them, it’s too late

#39

Post by bob33212 »

btilly wrote: post #32
isoprophlex wrote: post #3

This is the most profound thing I've read in a while. I'm tempted to whip up some numerical simulation to verify this to some extent... > But here’s the interesting part: conditioned on all the steps having succeeded, we should find ourselves near the end of the useful lifetime of our planet’s star—simply because the more time is available on a given planet, the better the odds there. I.e., look around the universe a…

Want something scary? The form of reasoning used is exactly that in the https://en.wikipedia.org/wiki/Doomsday_argument for why humanity is unlikely to last long, and almost certainly will not have a future where we break out and colonize most of the Solar System, let alone the stars. If you believe both arguments, the most likely outcome is that there is one more step on the way to Robin's argument. And that outcome…

We are within 500 years of creating millions of self sustaining spaceports. We are within 500 years of AGI. We are within 500 years of understanding quantum gravity. We are within 500 years of fixing biological death. The order we get to those and how they interplay and change the world matters so much that it doesn't make sense to worry about making predictions.

Re: Once we can see them, it’s too late

#40

Post by empiricus »

ivalm wrote: post #18

This kind of assumes that a “maxed out” civilization can expand at speed of light, but I don’t think it is given. It may very well be that meaningfully massive transport cannot exceed even a small fraction of c . After all, propulsion has to make energetic sense. 1. There is energy to get to speed 2. Mass of fuel to decelerate (and you have to accelerate that fuel in the beginning!) 3. Highly blue shifted CMB (that a…

If we think about the limits of the physical laws, one possibility is having a civilization that maximizes the available computation, and I suspect that this looks like some kind of black hole expanding with the speed of light.
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