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I used to be a big fan of SETI but I've come around to thinking it's probably a complete waste of time. This will probably get dismissed as "optimistic futuris

by cletus 7y ago

I used to be a big fan of SETI but I've come around to thinking it's probably a complete waste of time. This will probably get dismissed as "optimistic futurism" but I find the argument compelling that the future of any civilization is a Dyson Swarm for many reasons such as: - Planets are inefficient uses of mass to create living area. IIRC 1% of the mass of Mercury could make enough living area from habitats to house at least a million times as many people as we have now. - Gravity is a tyrant. Spinning a habitat achieves much the same thing without the negatives (as in the cost of launch). - This is entirely feasible on solar power alone. The importance of this is that practical fusion power is not a prerequisite. - This requires no new science. It's largely an engineering problem (albeit a significant one). I deliberately use the term "Swarm" here not "Sphere", which is true to the original concept. "Sphere" suggests this is a solid shell. That was never the intent. No known or theorized material could support a solid shell around the Sun. If you accept this premise then it's about the most un-subtle thing you could do and should be easily detectable millions of light years away in the IR spectrum. Why? Simple: - Stars generate heat - If the habitats hit by the energy from the star will heat up - In space you can only radiate heat away - If you don't remove that heat you'll ultimately fry - The wavelength from radiating heat is determined by the temperature of that object The standard counter to this is: Q: What if you recycle the heat instead? A: You can improve the efficiency but you can never perfectly consume all that heat. To do so would be to violate thermodynamics. If that's possible, well then all bets are off. A thousand years ago we were stabbing each others with swords. In a thousand years the above scenario is far from overly optimistic (IMHO). So in a cosmic blink of an eye we go from undetectable (from a SETI perspective) to being detectable from tens or hundreds of millions of light years away. So that's why I think SETI is pointless. Some say "you never know what fruit science will bear". While true, taken further this means it doesn't matter what science you invest in so why is SETI special?

mhh__ 7y ago
What do you actually think the IR spectrum would look like given that it would still be very close to a star that could potentially already saturate the measurement?
- cletus 7y ago
  So the telltale sign is a significant IR source with little to no visible light. Assuming the star is sufficiently encompassed by the swarm then it's still outputting energy, the swarm heats up and it needs to radiate that heat away. So a stellar level IR source that isn't visible is pretty weird. And if you wonder if the Swarm uses all the light such that little escapes, that's the whole point. Think of it like a fog. A fog can block light with a sufficiently large number of tiny water droplets but it isn't strictly "solid".
Dominisi 7y ago
What. IR radiation is bound by the same laws as all other forms of radiation, most namely the inverse square law. You would have to be radiating monumental amounts of energy, more than say a red dwarf, to be detectable from "millions of light years" away without fading into the cosmic background as noise. Think about it this way. With the naked eye you can see a bunch of individual distinguishable stars around ~4000 light years away. These stars produce more energy in a second than mankind has ever produced. But our closest neighbor, Proxima Centuari, you can't see with the naked eye. Its a red dwarf. And while it still produces unfathomable amounts of energy AND is the closest star to our own. You can't see it. TLDR: No, a Dyson swarm would not be detectable from "Millions of lightyears away"
- cletus 7y ago
  In what world do you conflate "detectable" with "visible with the naked eye", particularly when talking about IR which isn't in the visible spectrum anyway? What's more, the ratio of visible light to IR would be... highly abnormal. > You would have to be radiating monumental amounts of energy, You mean like the energy output of, you know, a star?
  - Dominisi 7y ago
    > In what world do you conflate "detectable" with "visible with the naked eye" They are literally synonymous and only vary in the instrument we are using to detect it. Your eye versus, say, an antenna. Visible light is also on the electromagnetic spectrum, it also abides by the inverse square law. > What's more, the ratio of visible light to IR would be... highly abnormal. No, it wouldn't. The sun radiates across the entire EM spectrum including IR and Visible light. It would take ~6200 structures that have the same area as the United States including Alaska (3.8 million square miles) to block out 1% of the EM radiation that the sun produces. >You mean like the energy output of, you know, a star? IF a sufficiently advanced civilization could magically conjure up enough materials in the solar system strip mining the solar system AND we had 100% efficiency in collecting then radiating 1% of the energy the sun gives off..... Yeah isn't gonna happen.

by cletus 7y ago

mhh__ 7y ago

What do you actually think the IR spectrum would look like given that it would still be very close to a star that could potentially already saturate the measurement?

cletus 7y ago
So the telltale sign is a significant IR source with little to no visible light. Assuming the star is sufficiently encompassed by the swarm then it's still outputting energy, the swarm heats up and it needs to radiate that heat away. So a stellar level IR source that isn't visible is pretty weird. And if you wonder if the Swarm uses all the light such that little escapes, that's the whole point. Think of it like a fog. A fog can block light with a sufficiently large number of tiny water droplets but it isn't strictly "solid".

Dominisi 7y ago

What. IR radiation is bound by the same laws as all other forms of radiation, most namely the inverse square law. You would have to be radiating monumental amounts of energy, more than say a red dwarf, to be detectable from "millions of light years" away without fading into the cosmic background as noise. Think about it this way. With the naked eye you can see a bunch of individual distinguishable stars around ~4000 light years away. These stars produce more energy in a second than mankind has ever produced. But our closest neighbor, Proxima Centuari, you can't see with the naked eye. Its a red dwarf. And while it still produces unfathomable amounts of energy AND is the closest star to our own. You can't see it. TLDR: No, a Dyson swarm would not be detectable from "Millions of lightyears away"

cletus 7y ago
In what world do you conflate "detectable" with "visible with the naked eye", particularly when talking about IR which isn't in the visible spectrum anyway? What's more, the ratio of visible light to IR would be... highly abnormal. > You would have to be radiating monumental amounts of energy, You mean like the energy output of, you know, a star?
- Dominisi 7y ago
  > In what world do you conflate "detectable" with "visible with the naked eye" They are literally synonymous and only vary in the instrument we are using to detect it. Your eye versus, say, an antenna. Visible light is also on the electromagnetic spectrum, it also abides by the inverse square law. > What's more, the ratio of visible light to IR would be... highly abnormal. No, it wouldn't. The sun radiates across the entire EM spectrum including IR and Visible light. It would take ~6200 structures that have the same area as the United States including Alaska (3.8 million square miles) to block out 1% of the EM radiation that the sun produces. >You mean like the energy output of, you know, a star? IF a sufficiently advanced civilization could magically conjure up enough materials in the solar system strip mining the solar system AND we had 100% efficiency in collecting then radiating 1% of the energy the sun gives off..... Yeah isn't gonna happen.