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Dumb physics question: If a dying civilization 99,000 light years away sent its last radio transmission 100,000 years ago, we'd never know it happened, right? M
by kerblang 5y ago
Dumb physics question: If a dying civilization 99,000 light years away sent its last radio transmission 100,000 years ago, we'd never know it happened, right? Maybe I'm missing something with those radio waves bouncing back and forth around us off of various big objects in the milky way.
- api 5y agoYou’re right. If we were not listening right when it passed us we would miss it. Any bouncing around would be so weak it probably could never be detected above background even with absurdly huge antennas.
- spaetzleesser 5y agoCorrect. We would not know.
- beecafe 5y agoGravitational lensing could give us a few more chances if they were in just the right place, but the event would have to be really massive (supernova level) for light echoes from interstellar material
- 7373737373 5y agoInterestingly, an infinite amount of chances, since signals can wrap around a black hole an arbitrary amount of times - they are just incredibly weak and have to be viewed from the right position!
- me_me_me 5y agothere is a distance beyond which radio signal decays into background noise. And even on the edge of it you are talking about enormous receivers to capture those transmissions. When looking into scales of universe its truly staggering how vast distances we are talking about.