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Comment by njtransit | Hacker News Reader

One difference between dark matter and Neptune is that the existence of Neptune is falsifiable. The formulation of dark matter inherently is not. Falsifiable hypotheses is the cornerstone of science.

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Is the existence of a planet so easily falsifiable? It hasn't been so long since the Planet Nine hypothesis started going around, and while we've observationally ruled out a big chunk of the original parameter space, there's still lots of room for a big dark dwarf planet to be floating around out there. It doesn't seem so different from how we've gradually been ruling out the parameter space for dark-matter observations.

Planets that reflect light are easy to detect.

Surely the idea of it being a new kind of matter that interacts gravitationally but not electromagnetically yields some testable result? Does it actually yield nothing testable with today’s experimental methods?

There is a lot of indirect evidence for dark matter. All the direct tests for dark matter particles we have performed have found nothing so far - but since we have no idea what it might be, there's a lot of possibilities to test.

"Evidence" in heavy scare quotes, considering, again, the tautological nature of the claims around the existence of dark matter. "Something must be here that we are missing" is, frankly, a bullshit hypothesis that need not be entertained unless researchers can actually prove there is some worthiness to the claim. Anything stronger than "maybe our theory is wrong" would suffice!

It is tendentious to point out only the difficulties in finding affirmative evidence for dark matter when MOND is doing no better in that regard. If, by that standard, dark matter is bullshit, then, mutatis mutandis, so is every other hypothesis that has been presented so far - but the observations that prompted them in the first place are not going away. It is inconsistent to call just one of them bullshit, and pointless to call them all that.

I'm not sure it's inherently unfalsifiable. There are some specific proposals for dark matter that could be ruled out by experiments, such as right-handed neutrinos: https://en.wikipedia.org/wiki/Sterile_neutrino#Sterile_neutr...

Maybe if you're being very broad in definitions then some class of proposals describable as "dark matter" might be unfalsifiable, but to be taken seriously as a scientific proposal I think it should be specific, concrete, and indeed testable, and there are a few of these within the "dark matter" class.

Again, we're in the perhaps unsatisfying position of having observations which don't cohere with our current theoretical understanding. What's the solution? It's not easy...

Have you ever encountered the phrase "grasping at straws"? The pursuit of explaining dark matter has gone through many waves of "we just need to invent detectors for this particle that has never been observed" and is littered with the wreckage.

Most of the history of physics involves making detectors for things that weren't previously observed... Consider: either most researchers in the field are stupid, for still pursuing an idea which you've apparently ruled out by simple reasoning, or your simple reasoning is fallacious

Almost: most of the history of physics is based on detectors being sensitive to things people didn't even know existed. Fits and starts based on happy accidents. The teleology of scientific progress is a myth. The most famous example is of course the Galilean moons.

Proposing detectors for particles that no one is even sure can exist is like setting up traps for Bigfoot...

I mean, dark matter may be discoverable, we just don't know how if it exists. There was time between the irregularities that were noticed in the orbit and the discovery of a new planet.

By that extremely simplistic logic, so is literally any other theory of gravity. This is not an argument, this is a flailing and empty justification.

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