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The hypothesis also makes a huge assumption: that if intelligent civilizations were common, they would be detectable by us. The radio waves emitted by our own c
by profmonocle 6y ago
The hypothesis also makes a huge assumption: that if intelligent civilizations were common, they would be detectable by us. The radio waves emitted by our own civilization don't go that far (compared to the distance between stars) before becoming nearly indistinguishable from background noise.
- rsynnott 6y agoAlso, they’re dying. Earth is probably less noisy now that 50 years ago.
- umanwizard 6y agoWhy is that the case?
- rsynnott 6y agoAs I understand it, the most visible stuff would be TV signal and over the horizon radar. TV signals have gotten less powerful, over the horizon radar is less of a big deal than it used to be. In another 50 years, will terrestrial TV, or any high power terrestrial radio, be a thing at all?
- jodrellblank 6y agoIt’s wasteful to spend the power to broadcast up into the sky when no viewers are up there; more focused directional transmitters, more sensitive receivers which allow lower power signals, more information sent over cable and fibre optic and undersea transmission lines and point-to-point satellite, more microwave and laser links compared to spam-everywhere radio broadcasts.
- garmaine 6y agoOn the other hand, stars are extremely wasteful. A technological civilization will, eventually, encase their sun in an energy extracting Dyson swarm. So why isn't the sky full of dim uniform-distribution infrared blobs?
- JauntTrooper 6y agoWould they still be detectable? Or could they capture enough energy that the stars would be barely noticeable, like trying to find a brown dwarf?
- saberdancer 6y agoI followed Tabby's Star news for a while (star that showed massive dips, speculation was that it is a dyson sphere being built). Most scientists believe that even if the star is encased in Dyson sphere that there would be excess infrared emissions as the sphere would need to vent heat. It would be hotter than surrounding space and thus visible. They are thus trying to detect such stars with higher mass and IR excess than expected, but so far there are not many candidates.
- garmaine 6y agoYou cannot simply absorb all the energy of the star and never emit it. The waste heat has to go somewhere. An efficient Dyson sphere would still emit lower energy infrared radiation in a way that would be detectable from out space-based observatories.
- Filligree 6y agoBecause there's no other intelligent life out there. You know that. But it bears mention, for others following along, that rampant artificial intelligence or similar does not count as a great filter candidate, because it would be just as visible as the life it's replacing. That doesn't leave a lot of fast-acting filters that could still be in our future, to be honest. Nuclear war? Sure, but we've avoided it too long for that to be a good one either.
- cgriswald 6y agoArtificial intelligence would necessarily have different physical needs than biological life. We can expect even our own AI to be a bit alien to our ways of thinking. Alien created AI would be completely alien to us. With different needs and different motivations, what evidence do we even look for, and if it is pervasive, how do we know we aren’t looking right at it?
- laretluval 6y agoSome proportion of civilizations would develop to the point that their signals are detectable to us (this is a parameter in the Drake equation). Since we haven't detected anyone, there must be some problem in reaching that point.
- StanislavPetrov 6y agoUnless: 1) The Drake Equation is wrong and its difficult to detect advanced civilizations. 2) We have detected other civilizations but we haven't recognized their signals properly. 3) We have detected other civilizations and the government is concealing it from us. 4) The UFO footage released recently by the Pentagon is proof of detection.
- nckthrn 6y agoIANAA, but I have always wondered if dark matter / energy is an explanation for 2)
- yreg 6y agoOur planetary system (formed 4.5B years ago) is comparatively late to the game. The waves from older civilizations should have been everywhere by now. If they were expansionist, they should have even collonised the whole Galaxy long ago.