15 Aug '15 22:39>
Famous phrase from Enrico Fermi, if there are aliens, where are they, why haven't we seen any sign of them?
The SETI project seems to me to be doomed to failure but of course a negative result is still useful.
Consider the expanding sphere of human activity in RF, say about 100 years or so of detectable RF from Earth. So that represents a wavefront 100 light years across where the leading edge is now about 100 light years from Earth. If we had radio telescopes on a planet 100 LY from Earth, we could detect our own radio waves.
We see however, the reduced usage of RF for TV and communications. Now cell towers transmit maybe 100 watts aimed to the horizon and so not much of that gets out of the atmosphere so it looks like the next 100 years or so will have less and less RF energy sent into space and say 100 years from now, we all switch to IR instead of RF for everything.
So now we will have a wavefront of about 200 light years in depth from beginning to end. So that wavefront flies through space and maybe reaches the other side of the galaxy in say 30,000 years. So in that time some alien develops radio telescopes but say they are too early by a couple thousand years, so our wavefront goes right by them undetected. Or the other scenario, 50,000 years later, a civilization develops radio telescopes, but now our signal has come and gone thousands of years earlier and in both cases, no detect.
Here on Earth, we would have to be very lucky to come across a detectable RF signal from any civilization in the galaxy because they may have gone through the same technological development that we are undergoing right now, so THEIR signals have come and gone or we are too early by say 10,000 years, both cases, no detect.
So That is my analysis of why we will most likely never detect an RF transmission from aliens in our galaxy or any other galaxy for that matter.
The SETI project seems to me to be doomed to failure but of course a negative result is still useful.
Consider the expanding sphere of human activity in RF, say about 100 years or so of detectable RF from Earth. So that represents a wavefront 100 light years across where the leading edge is now about 100 light years from Earth. If we had radio telescopes on a planet 100 LY from Earth, we could detect our own radio waves.
We see however, the reduced usage of RF for TV and communications. Now cell towers transmit maybe 100 watts aimed to the horizon and so not much of that gets out of the atmosphere so it looks like the next 100 years or so will have less and less RF energy sent into space and say 100 years from now, we all switch to IR instead of RF for everything.
So now we will have a wavefront of about 200 light years in depth from beginning to end. So that wavefront flies through space and maybe reaches the other side of the galaxy in say 30,000 years. So in that time some alien develops radio telescopes but say they are too early by a couple thousand years, so our wavefront goes right by them undetected. Or the other scenario, 50,000 years later, a civilization develops radio telescopes, but now our signal has come and gone thousands of years earlier and in both cases, no detect.
Here on Earth, we would have to be very lucky to come across a detectable RF signal from any civilization in the galaxy because they may have gone through the same technological development that we are undergoing right now, so THEIR signals have come and gone or we are too early by say 10,000 years, both cases, no detect.
So That is my analysis of why we will most likely never detect an RF transmission from aliens in our galaxy or any other galaxy for that matter.