If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth?
In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some important exceptions. High-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes) could be detected at distances of tens to hundreds of light-years with a setup similar to our best SETI experiments.
Every moment adds to our data of course, but the idea that we're at some sort of tipping point in how we should perceive the odds of extraterrestrial civilization is silly. Some of this feels like sour grapes from aging nerds who come to believe that it won't happen in their lifetimes, so it is obviously never gonna happen.
To be fair, the odds of an intelligent civilization arising at the exact same time as us are rather absurdly remote on astronomical timelines. Aliens should be somewhere between a billion years old to at least a few million, and that is plenty of time to colonize vast reaches of space and build telescope arrays in the scale of small galaxies with only known tech.
I agree though, it is rather silly to think that we’ve passed any point of significance in our search recently.
True, and I suppose that's a certain filter of its own. I suppose the main thing that makes me roll my eyes is that having done SETI by half measures for a handful of decades, the article is asking if it's time to assume that the rather presumptuous (though not absurd) zoo hypothesis is "the answer".
This all is what it is. The results so far imply virtually nothing about anything, except I suppose that there is not a very close civilization intentionally listening for our types of signals and eager to communicate back.
I mean i’d argue that the lack of any big sphere of space which is largely dark, save absolutely glowing in IR, does indicate that there is likely no one millions of years more advanced than us anywhere nearby. A K2 or K3 civilization millions of years more advanced than us should absolutely be visible to even our current telescopes if they were out there, and an absence of any massive otherwise explainable waste heat signatures seems to imply that they arn’t.
That is a result which tells us a lot about the Fermi Paradox, but hardly one that proves one solution over another. Similarly, we’ve recently found habitable zone exoplanets are not rare, but have yet to find any with a strong biosigniture. This does indicate to us that the odds of abiogenesis may actually just be that rare.
Negative results are still results, and indeed contrary to what the article thinks complex life being common around us while still lacking signs of intelligence would seem to be a lot stronger evidence of the Zoological Hypothesis than just a lot of dead rocks.
We’d need a sample size large enough to contain a bunch of positive signs of spacefaring intelligent aliens to ‘solve’ the Fermi Paradox though, so until and unless that comes along it’s all just idle speculation around the fact that we just don’t have the data to know.
Further images reveal how massive galaxies surrounded by dark matter, the invisible substance said to pervade the universe, warp space and magnify more distant galaxies behind them.
So Euclid’s images violate Euclid’s parallel postulate.
This is a great question. It’s like asking when a rock is too small to be a planet. I suspect there were be a definition eventually that mirrors the planetary definition – something like “spherical(ish) and clears its orbit”. The issue is that Mars would lose its two moons under that definition.
So we might end up with something like “moons” vs “natural satellites” and Mars will just have to suck it up.
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