291–300 of 307 posts
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All of this has happened before, and will happen again.
Can you explain that? I wouldn't have expected every possible situation to have occurred given the finite history of the universe. But I really have no idea what I'm talking about, so my request is serious.
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The milky way galaxy is about 200,000 light years in diameter, but only about 200 light years thick. Given this thickness, I imagine you'd need to look beyond the 200-light-year range to notice a significant influence of the plane of the galaxy on the distribution of stars (and planets).
This solar system orbits the galactic center every 250 million years or so; making us a young adult of around 18 Galactic years old, living in a suburb of quite a busy galaxy. Every eighteen year-old suburbanite[1] has already been pretty well socialised by local interactions in the context of a global system of local interactions, performed massively in parallel. [1] metaphors mixed and units of measure utterly mess…
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That's an unfounded presumption. It's like, nobody has considered that advanced life might not even feel a need to live on planets at all. It's expensive to get resources from, and there's a near limitless supply of easy to get smaller debris. Additionally, the difference a 2 billion year head start could make is hard to imagine. One thing that's not hard to imagine is that they don't live in meat bodies for most of…
We have sensitive telescopes. If there was life out there, we would have noticed. You would have astronomy conferences filled with people trying to figure out what all these weird spectra objects are, or trying to decipher all these structured radio observations.
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It's jarring to think that if intelligent life were on Kepler 452-b and observing Earth, we're so far away that they would be seeing our "civilizations" in 615 AD: shrinking global population as the old Roman and Byzantine empires are overrun by barbarian hordes and Arab conquest, with some pockets of human progress in China. They would have no way of knowing that the descendants of those squabbling warlords just coo…
> It's jarring to think that if intelligent life were on Kepler 452-b and observing Earth, we're so far away that they would be seeing our "civilizations" in 615 AD: shrinking global population as the old Roman and Byzantine empires are overrun by barbarian hordes and Arab conquest, with some pockets of human progress in China. Is there something uncivilized about the Arab conquest of Byzantine lands? Had the Kepler…
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by the time our today's signal reaches that planet, we ourselves will already be there to listen to it :)
FTL Travel?
At 2 billion years older than Earth, I can't begin to imagine what kinds of things could possibly be living on this planet. Given, of course, that it's got the right ingredients for life to arise. What if it's suffered huge extinctions recently? What if there's a domineering species out to conquer the planet just like humans? What if there's a society there more sophisticated than us? It's a very exciting discovery.
With a larger planet, they may have been inescapably bound to the surface for their world for millions of years by the tyranny of the rocket equation.
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> The engineer in me says that it's overwhelmingly likely that there's nothing alive there. Our planet has life in all kinds of niches. Why would an Earth-like planet not be overwhelmingly likely to have life on it? (I am an engineer also...)
True but all of our planet has an atmosphere conducive to supporting life. Don't get me wrong, I'm not saying that Earth-like planets generally won't support life. I have no idea how many will. It just seems unlikely that the first one found happens to tick all the relevant boxes. Having said that, the fact that they've found one so quickly, relatively speaking, seems like a good indicator that there are an awful lot…
The composition of Earth's atmosphere was pretty similar to Venus and Mars, before photosynthesis changed it to the current composition.
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Encrypted signals are not blindingly obvious. An encrypted radio transmission will appear as pure random noise and no different from all the rest of the noise that we pick up.
If an astronomer picks up a radio signal it is extremely obvious whether it is an artificial source or not. Natural sources have very inefficient spectra of very specific types. Artificial sources have very clear frequency cutoffs, having come from an antenna. Even frequency-hopping sources may jump around in a way that makes eavesdropping difficult, but if you stick around long enough on a single channel (as radio a…
Just think about it. The signals are going to be so weak by the time the photons get here they will be indistinguishable from the CMB.
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What? No, absolutely no we would not just see them with sensitive telescopes. Perhaps, if you're thinking of some sort of interstellar space travel, maybe we'd see the engines? But no, even that seems unlikely. Any space habitat of any plausible size will be completely undetectable, or at least indistinguishable from a planet. And I would think they'd be much smaller than that. And structured radio? Lots of possible…
I think you are completely misunderstanding the point. He have to vent heat somehow in the most efficient ways of doing so are not natural in their spectra. An encrypted radio transmission is still perfectly detectable -- you may not know what it says but you know that it is there. Artificial signals are blindingly obvious. And this is without getting into Dyson spheres and other efficient but detectable technology.
Yes, of course. And the heat of a star will make that heat completely invisible in comparison.
The "spectra" that heat would be vented at is infrared, which is infrared no matter the source.
Say you had some gargantuan fusion power harnessing space station in deep space. lots of assumptions here about alien cultures, but this is likely the easiest to detect. They will do whatever they do with their energy, and then vent the waste heat. That heat will be infrared. What does a dim infrared source look like (if even visible at all)? It looks like a brown dwarf. But this is assuming a lot. It assumes some alien would even build brown dwarf sized space stations. We don't know if or even why they would do that.
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> We have sensitive telescopes. If there was life out there, we would have noticed. I'm sorry, but that's way off. Our current telescopes can't even see the majority of the exoplanets in our galaxy; we are made aware of their existence by observing the behavior of their host star (wobbling/dimming). Unless something is extremely close, unfathomably enormous, or emitting/reflecting large amounts of electromagnetic rad…
They can see stars. There wouldn't be stars in a type 2 civilization. There would be amorphous blackbody spectra which we do not see.
https://en.wikipedia.org/wiki/Dyson_sphere#Search_for_extra-...