“Will we ever make contact with aliens ? Since the advent of broadcast radio, radio signals leaving Earth have traveled about 50 light-years, or 3 trillion miles. But our Milky Way galaxy alone is 6,0 trillion miles across. So those radio signals would have to go for centuries more before they even got a small fraction of the way across our galaxy. So a civilization somewhere else in our galaxy would have almost no chance of picking up our signals unless they were really nearby.
But don’t some radio waves get in black holes, do they keep going forever? I know they are photons
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Radio waves leave Earth in all directions. Some undoubtedly would be captured by black holes. If aliens had powerful enough detection devices, when the radio waves reached them, be a a hundred year from now or 10,0 years, they would obviously recognize then as originating from an intelligent species.
You have to think in geological time frames when it comes to this topic. Our own search for signal has only been going on for a few decade, but even so we have searched out to about 5 light years.
Just wait a few thousand years and have another listen, something just may be calling.
The big question is, “Should we answer?”
Light, including radio, will go forever unless absorbed or blocked. Black holes aren’t much of an issue. There are substances which can absorb radio and other frequencies of light. But the main thing is the inverse square law. At a distance of twice as far, the signal is a quarter as strong. At a distance of three times as far, the signal is a ninth as strong. Our largest single dish radio telescope is probably good for signals about 50 light years out, if a signal was produced there that was as powerful as RADAR from this dish. If the aliens had a dish the same size, and beamed our way while we were listening… Ignoring volume, this is about 1/1,0,0 of the area of our Galaxy. Then there’s also what frequency is best to listen to. We’re not really looking at much of the search space.
One interesting idea is to look for signals in the general direction of interesting astronomical phenomenon – such as nova or supernova events. Also, we’d broadcast in the opposite direction of these events. That way, alien astronomers would be more likely to pick up our signals.
If the outer space had only vaccum then radio waves would travel forever.
But the outer space is full of dust particles, smaller bodies, large bodies with huge gravitational pull, many other sources of huge amount of energy and the black holes.Therefore the radio waves cannot go forever. They lose energy when they strike with objects. The huge gravitational pull of some bodies pulls the waves too. Black holes pull the light waves too. Then there is interference caused by other sources of energy which either corrupts the signal or destroys it.
Black holes are smaller and have less pull than our own sun. They are very dense, which is why if you are right next to a black hole- ie, a few thousand miles- you will be stuck. But black holes are not magic vacuum cleaners that suck up everything. Space is big, and black holes are tiny.