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Advanced Civilizations Probably Don't Exist In Our Galactic Neighborhood
schwit1 writes: New observations of the best candidate galaxies now suggest that advanced civilizations are very rare or don't exist in the local universe. Researchers looked at several hundred nearby galaxies that emitted a high amount of mid-infrared radiation (abstract), which could possibly be produced as the waste heat from civilizations using energy on galactic scales.
They found: "The presence of radio emission at the levels expected from the correlation, suggests that the mid-IR emission is not heat from alien factories but more likely emission from dust — for example, dust generated and heated by regions of massive star formation. As Professor Garrett explains: 'the original research at Penn State has already told us that such systems are very rare but the new analysis suggests that this is probably an understatement, and that advanced Kardashev Type III civilizations basically don't exist in the local Universe.'"
Obviously, the uncertainty of these results is quite high. Nonetheless, the results indicate that either humanity really is the only intelligent species in this part of the universe, or advanced civilizations are far more efficient in their use of energy than is reasonable to assume.
They found: "The presence of radio emission at the levels expected from the correlation, suggests that the mid-IR emission is not heat from alien factories but more likely emission from dust — for example, dust generated and heated by regions of massive star formation. As Professor Garrett explains: 'the original research at Penn State has already told us that such systems are very rare but the new analysis suggests that this is probably an understatement, and that advanced Kardashev Type III civilizations basically don't exist in the local Universe.'"
Obviously, the uncertainty of these results is quite high. Nonetheless, the results indicate that either humanity really is the only intelligent species in this part of the universe, or advanced civilizations are far more efficient in their use of energy than is reasonable to assume.
Planets are common. Planets within the habitable zone look like they are common. So, is this evidence of the Great Filter - https://en.wikipedia.org/wiki/... ?
There is this huge assumption that alien civilizations will be emitting large amounts of waste heat. What happens if they are just more efficient than us?
Mmmno. The research doesn't indicate anything like that at all. They were looking for civilizations that harness energy and resources at galactic scales, ie. Kardashev III - level civilizations. Mankind haven't even reached Kardashev I yet. The submitter didn't understand what they were reading and jumped to conclusions.
...as of thousands to millions of years ago, anyway? Speed of light, and all.
It is known that there are an infinite number of worlds, simply because there is an infinite amount of space for them to be in. However, not every one of them is inhabited. Therefore, there must be a finite number of inhabited worlds. Any finite number divided by infinity is as near to nothing as makes no odds, so the average population of all the planets in the Universe can be said to be zero. From this it follows that the population of the whole Universe is also zero, and that any people you may meet from time to time are merely the products of a deranged imagination.
I'm no expert, but I remember reading that digital communication is virtually undetectable at galactic distances, because it fades way more quickly and becomes indistinguishable from background noise.
About the heat emissions... dunno what to say. An advanced civilization might be so thinned out, galactic-wise that it would emit an insignificant amount of heat. Or it could be a race which doesn't reproduce easily and lives for a long time, e.g. a couple million sentient beings per planet, who need very little in terms of energy. The possibilities are limitless.
Just wondering... how much heat does mankind generate? Can someone 1000 LY away detect our heat emissions?
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
Perhaps intelligent civilization will originate from Earth and spread across the Universe. Everything has a beginning.
You can't escape waste heat; it's part of entropy. Unless maybe you open a subspace portal or something like that, but obviously our understanding of physics doesn't allow for anything of that sort.
This is the problem with trying to understand hypothetical advanced civilizations; if any really exist, most likely they're figured out things in physics which we still have no clue about. We only started figuring out quantum mechanics about a century ago, and without that we wouldn't have semiconductors, including microchips and LEDs. We've barely even gotten off our own planet.
I'm no expert, but I remember reading that digital communication is virtually undetectable at galactic distances, because it fades way more quickly and becomes indistinguishable from background noise.
Nah, it's worse than that. Spectrum is finite, so the incentive over time is to use interesting encoding techniques to smear the data across the available spectrum. If you don't know the protocols, a given frequency mostly looks like noise in the time domain. And there are similar incentives to fill up the frequency domain. And there's incentive to use lower power, so that more transmitters can share the frequency, so those are all going to merge into a mess, too.
Basically, by design our radio output is tending towards noise which will be impossible to differentiate from a light year away.
It's kinda hard to have evidence of aliens if you never bother to leave your own planet, or send any probes beyond your own star system. Basically, such evidence would require the aliens to travel here to visit us. If there's any aliens out there in nuclear-powered generation ships or whatever, there's no way for us to see them until they're in orbit around our planet.
There's a whole galaxy out there we haven't explored, plus billions more galaxies beyond that. Just because we don't have reliable evidence of aliens visiting us here on Earth (aside from things like Roswell and cattle mutilations and claims of abductions) doesn't mean there aren't any out there anywhere; it's ridiculously arrogant and stupid to even think that. There could be aliens with a civilization similar to ours on one of the planets at our nearest neighbor, Alpha Centauri, and we wouldn't know it because we have no way of seeing them. Maybe they're technologically where we were in 1830 and haven't developed radio yet, or maybe they're 150 years ahead of us and have gone to spread-spectrum communication so their transmissions just look like noise to us and we missed all the detectable stuff.
All this really says is that civilizations emitting IR were not found in Y regions of the galaxy at time X in history.
Since these regions are different 'light years' away in distance, what reaches us is not the current state of what's going on there.
An advanced planet 500 light years from Earth looking today for other advanced race would not find us since 500 years ago we were not creating IR signatures.
Likewise, if we found such a signature, the possibility exists that during the time the IR got here, that civilization ceased to exist.
How do we even know the warm dust isn't the substrate for an advanced civilization?
Don't just stand there, get that other dog!