Astronomy / Space The Fermi Paradox — Where Are All The Aliens?

[Talarin]

Radiowaves are basically lightwaves on a wavelength human eyes can't see. They're produced by stars and other sources as well as human activity, but radiotelescopes can see those wavelengths quite easily. If a rocky planet was producing way more radiowaves across the entire radio spectrum than, for example, a nearby star that would be a massive anomaly which would indicate a high probability of technology on that planet.

Sorry, I don't mean to be argumentative - but the inverse square law applies here. Radiotelescopes are able to see emissions on a particular wavelength (provided you're actually looking at that wavelength at that particular time), but the signal strength would be incredibly low at interstellar distances.

We certainly couldn't detect a civilisation broadcasting in a way similar to ourselves at those distances with current technology.

It's far more likely that we'd be able to detect suspected alien civilisations through spectral analysis of a exo-planet's atmosphere, but we can bearly do that for super-massive planets right now - not likely candidates for life based on our expectations.

See this for a relatively recent pop-article on the topic.

 

[Ziljan]

We certainly couldn't detect a civilisation broadcasting in a way similar to ourselves at those distances with current technology.

Actually, we could detect fairly weak isotropic radio signals transmitted from 200,000 LY away with a sufficiently huge telescope array, a narrow enough frequency range, and a long enough integration time to boost the signal to noise ratio. And all of that IF we were pointed at the right star.

More important than the inverse square law, however, is the universal speed limit. To detect signals from intelligent life on earth, an alien would need be within 100 LY of Earth. Thanks to this wonderful game, everyone here is now familiar with how staggeringly small a 200 LY wide bubble really is compared to the vastness of the Milky Way. Even by the year 3301, that bubble of signal will only extend ~1,200 LY beyond the borders of "human space".

That being said, evidence of biological life has been transmitting long enough to reach the furthest places in the galaxy. Even though we don't yet posses the tech to see that far, the rate of progress on our ability to detect non-intelligent is fairly impressive. Likely, any alien civ that has been around that long will have surmounted the technical issues of detecting life from a distance.


To address the OP:

Space is incredibly dangerous. Of all of the dangers to a lasting space faring civilization, the natural hazards of space itself are the most insurmountable. Even if we could send generational ships to colonize the Galaxy, or send robot proxies, the likelihood of their survival or success for each trip is only slightly higher than the odds of life occurring naturally in that target star system. In this game, space is a warm welcoming bathtub. The reality is very much the opposite. The odds are that the ship would start to malfunction long before it reached its target, and everyone on board would die from cancer before they could reproduce. That is all before they encountered the even bigger danger of trying to successfully land on then actually survive long enough to colonize an alien world. Never mind the biological chaos that would ensue from alien microbes meeting for the first time.


just realized my post was #42 in a thread about life, the universe, and everything... Coincidence?

 

[Mephane]

Mu guess is that, at first, AI will be looking at us as Gods. A creator. Then the AI atheists will eventually show up, and that's when we should really think about spreading out to other planets

I would rather expect AI to regard us not as actual gods, more as parents, initially, then rather like we do the other great apes (bonobo etc.), and as it grows ever more intelligent, we will be like ants to them. And it'll probably be the other way round, the AI leaving the confinement of Earth behind, and spreading into space entirely without us; because all our biological disadvantages in zero gravity and vacuum and cold temperatures are basically moot for AI, energy is much easier to collect in space (constant, 100% predictable sunlight), resources are plentiful (asteroids) and there is no interference by those pesky humans who would want you to perform menial tasks all day long.