The Last of the Universe’s Ordinary Matter Has Been Found
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The Last of the Universe’s Ordinary Matter Has Been Found
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Re: The Last of the Universe’s Ordinary Matter Has Been Found
#2There must be regions of the universe where this "not very dense" gas is dense enough to use a ramscoop
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#3There must be regions of the universe where this "not very dense" gas is dense enough to use a ramscoop
Probably more in high-gravity locations, such as planets and stars. Thinking about the Juno satellite orbit, would it be better/easier/cheaper to hang a mining station in orbit around Jupiter, or have a satellite/ship dip into Jupiter's atmosphere every orbit?
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#4There must be regions of the universe where this "not very dense" gas is dense enough to use a ramscoop
Likely only around jupiter-like planets, if any large region of gas was that dense it would quickly collapse into either a gas giant or star or even multiple stars.
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#5There must be regions of the universe where this "not very dense" gas is dense enough to use a ramscoop
Probably more in high-gravity locations, such as planets and stars. Thinking about the Juno satellite orbit, would it be better/easier/cheaper to hang a mining station in orbit around Jupiter, or have a satellite/ship dip into Jupiter's atmosphere every orbit?
Counterintuitively, the energy costs are basically the same. Whether you dive in to pick it up, or run into it out in space, you will still have to accelerate the gas to orbital velocities before you can cram it into a tank. Some of the gas in space may already be moving very fast, may even be in an orbit, but it is probably not aligned with the orbit of your tank.
Either way, the energy required to maintain operations anywhere near Jupiter means you probably want to find your hydrogen somewhere else.
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#6The hypothesis is they should see CMB distortion between galaxies, which is hidden by the distortion caused by the galaxies themselves. The solution was to assume they were removing the distortion caused by the galaxy halo, and what was left was the original distortion they were looking for.
sounds like the work to rule out false-positives would be huge. This is putting a lot of weight on a technique that is not fully described in the paper (i might have missed, just glanced at them for now, and i am an amateur that just like to fiddle with similar data).
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#7The hypothesis is they should see CMB distortion between galaxies, which is hidden by the distortion caused by the galaxies themselves. The solution was to assume they were removing the distortion caused by the galaxy halo, and what was left was the original distortion they were looking for. sounds like the work to rule out false-positives would be huge. This is putting a lot of weight on a technique that is not full…
There's more confidence in the result because two teams using very different methods have arrived at the same conclusion.
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#8Slightly related, I wonder if anyone has figured out the density of interstellar comet or asteroid like objects.
I notice that Oumuamua happened to pass within some 20 million km of earth within a decade or so of having systems in place to spot it. Wouldn't this imply there are an awful lot of them?
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#9The hypothesis is they should see CMB distortion between galaxies, which is hidden by the distortion caused by the galaxies themselves. The solution was to assume they were removing the distortion caused by the galaxy halo, and what was left was the original distortion they were looking for. sounds like the work to rule out false-positives would be huge. This is putting a lot of weight on a technique that is not full…
I'm not really sure of what you mean by false positives.
After my understanding of the stacking technique as used in other contexts in astrophysics and without going into too much details :
The problem they were facing is that the signal to noise of the images of the filaments was too low to say that they had detected anything in any individual images. However by stacking (adding) images they were able to detect it because the signal grows roughly with N (N being the number of images) and the noise grows with sqrt(N). So by stacking enough images you'll get the signal to noise necessary to say you've detected sth.
Re: The Last of the Universe’s Ordinary Matter Has Been Found
#10The hypothesis is they should see CMB distortion between galaxies, which is hidden by the distortion caused by the galaxies themselves. The solution was to assume they were removing the distortion caused by the galaxy halo, and what was left was the original distortion they were looking for. sounds like the work to rule out false-positives would be huge. This is putting a lot of weight on a technique that is not full…
I'm not really sure of what you mean by false positives. After my understanding of the stacking technique as used in other contexts in astrophysics and without going into too much details : The problem they were facing is that the signal to noise of the images of the filaments was too low to say that they had detected anything in any individual images. However by stacking (adding) images they were able to detect it b…
Think like that: there are two bright lights in front of you. There will always be a halo between those two bright lights.
Now, my hypothesis is that "between all two bright lights, there is third, dimmer one, hidding". And then i prove it by filtering X from the two bright light halo, and prove that Y is left proving that the third light is there.
Now, how can i be sure Y is really a third dimmer light? and not just noise on the function i used to try to clean up the halo of the two bright light?