141–150 of 353 posts
The first alien we will ever encounter is likely a neural network we built with our hands.
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Then you need to explain how life on Earth started a short period after it cooled down. Yes, it took a long time for complex life forms to emerge but life itself started right off the bat.
"Short period" and "right off the bat" are terms without meaning. What sets the scale of "short"?
In my opinion, the excitement occasioned by the discovery of so many exoplanets has clouded our collective judgement on the Fermi Paradox, leading the overwhelmingly most probable resolution to be underemphasized. Namely: there is no life out there. Not due to baroque mechanisms such as techno-self-destruction but just due to its sheer unlikeliness. As large as the number of stars in the observable universe is (let’s…
For a long time we weren't at all sure whether the expansion of the universe would stop, leading to a "big crunch", or continue forever, slowing down for eternity. Then we found the other option appeared to be supported by observational evidence: the expansion is accelarating. We're in a similar position with finding life elsewhere. The vague error bars in many terms in the Drake (so-called) equation shouldn't be rea…
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We are actually running out of places in our history to fit a great filter. Most of the events in our evolution seem probable, even inevitable. In fact the only place IMO that's really left is the emergence of the first self replicating RNA molecule. But even that seems too probable to be a great filter. And if its not behind us, it has to be in-front of us or we are under a great misapprehension about the nature of…
BS. Filter 1. If we had no large moon, roughly every 30 million years or so our axial tilt would become too extreme for life. We do not have another example of a planet with a moon to rival ours in relative size. Filter 2. Without Jupiter acting as a cosmic vacuum cleaner, we'd predictably be hit by enough asteroids and comets that we'd never have evolved. In thousands of solar systems that we've found, we've found l…
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I would guess advanced civs don't bother with radio and look instead for direct visual and spectrographic evidence. We're very close to being able to look for spectrographic evidence and maybe 50-100 years from building a telescope that uses a planet's gravity well for optical enlargement. Earth already looks quite distinctive spectrographically because of the free oxygen, water, and CO2. In the general case you look…
To me it looks more like a radioactive waste dump than a beacon.
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"Short period" and "right off the bat" are terms without meaning. What sets the scale of "short"?
Easy to look up! By current estimates Earth cooled enough to have liquid water about 4.46B years ago and the first RNA emerged around 4.35B years ago. So it took just over 100 million years for simple forms of life to emerge.
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Or they're not communicating using EM. And maybe they can't get off planet. And maybe the mean distance between pairs of civilizations is so large that interstellar travel is just not practical at all for any of them and us as well.
Yes, these are alternative explanations. The explanation that is surprisingly undermentioned is the one I put forward: there is no life.
I prefer the Dark Forest interpretation of the Fermi Paradox: https://en.wikipedia.org/wiki/Dark_forest_hypothesis
But it's not a paradox at all.
Imagine there's an alien civilization in our galactic neighbor Proxima Centauri. How would we know they are there?
To make it more plausible. Let's say we figure out a way to send a space probe to Proxima Centauri. How do we communicate with that probe? Easy, you say, just like we communicate with the Voyagers: they point a reasonably large parabolic antenna at us, we point a point a much larger one at them, and we chat all day long.
Except that Proxima Centauri is 2000 times farther that Voyager. And signals decrease with the square of the distance. By the time Voyager gets to be 4.25 light years away from Earth, their puny 22W antenna will send us a signal that's 4 million times weaker than what they send us now (when we get less than 200 bits/second).
It's actually worse than that, of course. If Voyager were to send a signal from some arbitrary place 4.25 light years away, we'd get it as something 4 million times weaker. But if that place is in the solar system of Proxima Centauri, it's like us looking straight at the headlights of an incoming car. That very weak signal will need to be extracted from the extraordinarily bright noise coming from the star that's roughly speaking about 1 second of arc away from it.
Now imagine that instead of Voyager, it's just some aliens that are not pointing an antenna straight at us, but just minding their own business. They could be launching rockets, watching satellite TV, waging wars, and from time to time lobbing Himars at each others, and even nukes. How would we know they are there?
And now finally imagine that there are no aliens in the Proxima Centauri system, by the luck of the draw, but there are in 5% of all the star systems in the galaxy. Only the closest ones to us are 40 light years away, instead of 4. That's another reduction in signal by a factor of 100.
The only question is not why we didn't "see" any aliens so far. It's why we wasted so much money on SETI. Was Carl Sagan not able to do the back of the envelope calculation I just did here?