341–350 of 365 posts
JSWT... again the most formidable piece of equipment ever shot into outer space. That think is going to shake our understanding of the Universe to its foundations a couple times around
I think you mean JWST, not to be confused with JSON Web Tokens :)
How far off are we from being able to image an exoplanet?
My math is below.
Note: I'm not an astronomer.
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The angular resolution limit for a telescope is roughly the wavelength of the light it's sensitive to over the diameter.
If we want to sense things 10m across, with light at the shorter end of the visible spectrum (400 nm), we'd need a telescope with a diameter of about 1/4th of an AU (i.e. the distance from the earth to the sun), around 40 million kilometers.
More practically we could use a telescope array with this diameter, which could conveniently be in lot of orbits about 1 AU out. But the area is still a problem: assuming this 100m^2 object is as bright as it would be on earth under midday sun, it's going to be reflecting around 100 kw of energy. One of these photons has an energy of around 3 eV, so we're getting 2e23 of them a second. Unfortunately these spread out over a sphere with a surface area of 1e31 km^2 by the time they reach earth, meaning we see one every second if we have a telescope array with an area of 50 million square km.
Ok, so let's go kind of sci-fi and say we can build a 30 km diameter space telescope. It would be impressive (and unprecedented) but since it's floating in space and could be made of thin material you might be able to imagine it with today's technology and a lot of coordination. That gets us around 1000 square km! Now we just do it 50,000 more times.
Great, now we have 1 Hz of photons coming from each 100 m^2 patch of Alien Manhattan! I'm sure in the process of building 50k mega-projects we'll figure out a way to filter out the noise, and with a few years of integration we'll have a nice snapshot!
Earlier quoted context omitted.
Cooperation depends on you and your potential allies surviving long enough to be able to contact each other, and being strong enough to counter the threat. We don't know whether we will develop capabilities fast enough to counter an enemy that e.g. at the first sign of radio started accelerating a bunch of super-dense (hence small, hard to detect and stop) kinetic kill devices our way. MAD is utter bunk. It depends o…
Cooperation only depends on anyone , in the history of ever, having at any point survived long enough to contact each other and form an alliance. Once a critical mass of parties that prefer cooperation has been reached, all future cooperative parties are at an automatic advantage over aggressive parties. You can see shades this of this, e.g., in the difference between single-round versus iterated Prisoner's Dilemmas.…
No, that does not follow, because it assumes any cooperation gives sufficient leverage to be able to resist. But an enemy lobbing kinetic kill devices at high speed from locations that does not give them away would require far more advanced tech to stop.
> What do you think the long-term prospects are of a species that goes around flinging RKVs at people? No more North America and no more Eurasia, if that happened. Maybe South America and Africa can pick up the pieces. Just because irrational hyperaggressive actors can briefly exist doesn't mean you're likely to encounter them. They won't survive for long.
On Earth. In space, throwing kinetic kill devices at people won't affect your own territory, and can at least in theory be done without any possibility of tracing it back to you - you "just" need to accelerate a bunch of them outward to starting positions far from your home system. Any civilization smart enough to be able to build devices like that would be smart enough to build autonomous ones that would become operatonal first when in a position that wouldn't give them away.
> MAD exists whether or not any particular participant believes in it, because it's just the cause and effect of competing powers each with their own agency. Or else we wouldn't be here. Even the Soviets knew that a possible US first strike was better than a guaranteed US retaliatory strike, which would happen if they struck first.
The point of the lessons Able Archer is that there were strong indications the Soviets thought there was a line at which point a first strike to preempt a US first strike would be preferable, and that they thought they were getting close to that line.
> The whole "Fermi Paradox" arguments are based on an extreme form of "eventually, we should expect to see aliens, so why haven't we already?" This doesn't mean aggressive civilizations don't exist, but the reasons to think they're prevalent are overblown.
I've seen nobody suggest we have strong reasons to think they are prevalent. That is missing the point. It's one of many possibilities, but one where the temporary existence of even one in any given "neighbourhood" close enough to strike before we've gotten advanced enough to defend against compact kinetic kill devices hammering us at a decent percentage of c (or worse options we don't know about) would mean we'd already be doomed without knowing about it.
It doesn't even need to be a long-lived one. There just need to have been one alive when our first radio signals hit them.
It doesn't even need to successfully kill most civilization. For it to resolve the Fermi Paradox, attacks just need to happen often enough that those who survive quickly decides hiding is the best option just in case.
Earlier quoted context omitted.
I think by the time we get to modern humans it would only be a matter of time for technology to develop to something like the current stage. The main evidence I can think of is the independent development of agriculture in about 4-5 regions, and the independent development of large complex civilizations in the Americas and Eurasia. Humans are cultural learners, so this allowed cumulative cultural evolution from at le…
Humans only started planting grain about 12k years ago. Anatomically modern humans were gathering wild grain, but not planting grain, for about 100k years. Given this very long period of stagnation, I don't think humanities ascension was an inevitability.
In any case, the seeming stagnation is part of what I meant by the early part of an exponential curve looking flat: broadly it might look like not much is happening, but there are small changes all the time.
Lack of evidence is also a problem when looking that far back: we have little concrete evidence of what these people were doing with wood, fibres, and other perishable materials.
Having said that, archaeologists used to talk about a "cultural revolution" that happened 20-30k years ago. (Maybe they still talk about it, I just haven't looked at the research recently). This was the period of the famous Lascaux cave paintings and what looks like an explosion of greater complexity in tool assemblages. So it's possible there was some rare cognitive leap at that time, or again it could be that we lack the evidence that would show the more gradual progression.
Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me. Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life d…
If life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Suggesting that our demise t…
We have some ideas for crossing huge distances, but none of them are really practical. There are ideas for accelerating tiny probes with light sails, but when we manage to send them somewhere with 90% of the speed of light, we have no way to decelerate them again in a controlled fashion.
What I want to say is: there's good reason to think that doing anything over 200 light years or so is just infeasible.
If that time is a few hundred years, then very few happen to be functioning _now_ (in relativistic meaning) and very far away to have meaningful contact.
How far off are we from being able to image an exoplanet?
Directly imaging an exoplanet has been done about 20 times (maybe more, by now). If you're asking how far are we from resolving an exoplanet to more than a single point of light, the answer is we will never be able to do that from this distance.
Failing that, you’d need thousands of optical interferometers larger than the Hubble spread across a distance wider than the Earth.
Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me. Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life d…
If life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Suggesting that our demise t…
Earlier quoted context omitted.
I highly doubt much of the bacteria would care. The amoeba probably wouldn’t either. Also, rodents have already survived such impacts. All mammals alive today are alive because our ancestors didn’t die with dinosaurs.
Suppose the asteroid is much bigger than the one that ended the dinosaurs.
Earlier quoted context omitted.
I think it's a natural product of curiosity. And I think that intelligent life would only be so because of curiosity. You want to figure things out or you're interested in seeing what happens when you fuck around with things. So I think a technological progression is a natural progression for intelligent life. Does that make sense? I feel like I'm not explaining myself well.
Lots of animals have been curious for hundreds of millions of years, but technology more advanced than breaking bits off rocks and sticks has only been around a couple thousand years. If you say it's a "natural progression", you also have to say there are serious barriers that most species will never pass.