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View Full Version : Looking for those little green men !



kevin1981
2019-Jan-19, 01:25 PM
Hiya..

I was just wondering, say there is no other life in our galaxy, okay that is fair enough..

But what if there are 3 planets spaced out from each other in the Andromeda galaxy that have intelligent life like us, do we have the sufficient technology to be
able to discover them ?

Spacedude
2019-Jan-19, 03:09 PM
I would say it's highly doubtful. You say "life like us", if you mean just as technically advanced as us then we'd still have to wait at least 2.5 million years for any radio signals to reach us, and I would assume that any signal sent would have to be purposely directed at us just as we had sent a past signal/message from Arecibo back in 1974 towards the globular star cluster M13.

kevin1981
2019-Jan-19, 07:38 PM
Highly doubtful, yeah i expected as much !

I done a rough calculation earlier. Say there are one hundred billion galaxies in the observable part of our universe and on average life springs up once every
ten thousand galaxies then that is still ten million galaxies with life. So life being rather rare could still be quite a big number due to the sheer vastness of it all.

What percentage evolves into a species that can build space shuttles and radio transmitters is anybody's guess. It is basically an unanswerable question i suppose.

Grey
2019-Jan-19, 09:43 PM
In this thread (https://forum.cosmoquest.org/showthread.php?169150-radio-waves-detectable-from-another-galaxy), I mentioned this site (https://stason.org/TULARC/science-engineering/astronomy/100-How-far-away-could-we-detect-radio-transmissions.html). Table 1 says that an Arecibo-size transmitter could be detected by an Arecibo size receiver at about 720 light years. Even if you bumped that up a few notches, getting a signal to Andromeda seems like it would be out of range. And that's with a deliberately sent signal aimed at us. It would be even harder to pick up stray signals. I can't imagine that we could detect an extragalactic civilization unless they were so advanced that they were doing engineering on a galactic scale (for example, herding all of their home galaxy's stars into orbits with some clear geometric pattern).

ronin
2019-Jan-20, 02:07 AM
I have read in several article that with our current technology we would be unable to detect signals with strength comparable to what we ourselves broadcast beyond 10 light years or so. And also consider that out Radio "Fingerprint" is diminishing every year thanks satellite technology. In fact our primary radio signature today is military radar pulses which is very similar to natural radio sources.

kevin1981
2019-Apr-06, 07:54 PM
How about if there was another civilisation with our level of technology on the other side of the Milky Way, would we be able to detect them.. ?

Van Rijn
2019-Apr-06, 09:30 PM
How about if there was another civilisation with our level of technology on the other side of the Milky Way, would we be able to detect them.. ?

Short answer: As we are, no. Though there have been ideas about much larger antenna arrays than Arecibo that could be built with today’s technology, so perhaps if both civilizations built massive antennas, pointed them in the right direction at the right time, it might just be technologically possible, if practically unlikely. It actually would be slightly easier to detect a civilization in one of the nearby satellite galaxies.

kevin1981
2019-Apr-06, 10:27 PM
Thanks.