41–48 of 48 posts
We’re pointing the JWT pretty far out, so why wouldn’t we just point a camera at this thing?
JWST has a field of view of 2.2 arcminutes. Same as a 0.6 millimeter pinhole at a distance of 1 meter. It's not a telescope for blind surveying where you don't know where to look (as is the case here)—there's much more suited telescopes for that.
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And then we lose those people completely when the "facts" change. Better not to call them facts in the first place.
The facts don't change. Apples fell to the ground when we thought newtonian gravity was correct, they still fall to the ground now that general relativity is the accepted explanation. Theories are explanations of factual observations. The observation of the phenomenon we're calling dark matter is as factual as apples falling to the ground. The explanation is subject to change as we learn more, but the facts won't.
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The facts don't change. Apples fell to the ground when we thought newtonian gravity was correct, they still fall to the ground now that general relativity is the accepted explanation. Theories are explanations of factual observations. The observation of the phenomenon we're calling dark matter is as factual as apples falling to the ground. The explanation is subject to change as we learn more, but the facts won't.
dotnet00 said we should call dark matter an "absolute fact".
How is this different than when we pretended there was another planet, Vulcan, to reconcile Newtonian physics with the unexplainable phenomenons physicists noticed until others and eventually Einstein came along to prove that the theory was wrong ?
To be fair, this is also more or less how we found Neptune. Boring, simple explanations are often the right ones. Not every horse is secretly a zebra. https://en.wikipedia.org/wiki/Discovery_of_Neptune - "The planet Neptune was mathematically predicted before it was directly observed. With a prediction by Urbain Le Verrier, telescopic observations confirming the existence of a major planet were made on the night of S…
They are only half way there (afaik, but I could have misunderstood their point)
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But the thing is it's only the angular speed of star systems in some galaxies. We have also found galaxies that behave differently, as if they have no dark matter. This is very easily explained with dark matter theory - they actually don't have dark matter. Any theory that modifies gravity needs to explain why we only sometimes modify gravity. Further, while that was the observation dark matter was originally introdu…
Thank you for the explanation. What I don't like about this, is that we take the observations, apply some custom guesses as to why the spacetime is folded differently and... there you go, your formulas now match. It smells too much like the explanation of geocentric system, where they invented that planets also circle around a perceived dot on their trajectory path and that happily coincides with the Earth's rotation…
> I think what we are missing is that these behaviors need to be predictable. We don't know where these anomalies in spacetime curvature will be and why they are there.
But we do! We can see galaxies that have been stripped of their dark matter and we can find nearby the dark matter that was stripped. We can predict, based on our theory of dark matter where these gravitational anomalies will be, then we look there and lo and behold we see them. We aren't applying custom guesses to match our observation, the universe just happens to match exactly what we'd expect it to look like if it contained a bunch of matter that didn't interact with the electromagnetic force.
> I think dark matter is a bad name for the unexplained spacetime curvatures (warpings?, wrinkles?).
Dark matter isn't the space time curves, which aren't particularly special. All massive particles produce such warping, and we just call it gravity. Dark matter is matter (stuff that interacts with gravity) which is dark (does not interact with light). We would expect it, assuming it exists, to produce such warping of spacetime, which again is exactly what we see.
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This, ether, and dark matter. The equations don’t agree with observations so we invent a thing we have not observed to explain it. I wish it would be explained like this in popular science, went to a planetarium and they presented dark matter as absolute fact.
For the average person, dark matter should be presented as absolute fact. It's the leading explanation that best explains most of the associated phenomenon, and the average person has repeatedly shown themselves to be unable to understand what a scientist means when they call something a theory. Emphasizing that we haven't explicitly discovered what dark matter actually consists of inevitably leads to people who don'…
It is like a boy calculating physics homework, only to be 30% off, so he will add some constant to get to result he wants. It sounds ridiculous, does it? Well dark matter/energy is that constant to get result we expect.
We’re pointing the JWT pretty far out, so why wouldn’t we just point a camera at this thing?
Point it where? We don't know exactly where to look, and it might be far out enough to be barely visible. Pointing a telescope at it requires a precise location.
Also it's predicted that a star comes with 1,500 AU of the sun every billion years or so, a star could have thrown things out of whack and left.
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If you step in a pile of dog doo, that's evidence there's a dog. Now just point your camera at it...
Hey, no stupid questions right? But if you suspect it’s a planet, you know it’s in orbit around the sun. Feels like something we can track.
Our planets' orbit do tend to be somehow aligned, so you could make the (possibly wrong) assumption that the 9th planet is also somehow aligned. This might reduce the search space by 50%+.... but even then you'd still be several orders of magnitude off by the precision needed to go looking for it.