I think you are confused about what dark matter is believed to be.
Dark Matter is believed to be non-baryonic matter. Simple as that. We have direct observations of non-baryonic matter. The largest telescopes in the world are actually designed to detect non-baryonic matter (and they succeed). They have to be buried deep in the earth because it is too easy to get noise from various types of radiation, but this is no problem, because non-baryonic matter doesn’t interact with ordinary matter except in the rarest of situations.
Neutrinos are probably the most well known type of Dark Matter, and those have certainly been directly observed. Scientists are even reasonably certain of the tonnage of neutrinos produced each year by our Sun. There are believed to be other types of Dark Matter, but the nature of the particles make them extremely difficult to study. But not impossible.
The point is that expectations don’t match up with reality, and the only sensible explanation is that the difference is caused by non-baryonic matter (since if it were baryonic, we’d almost certainly be able to see it). You can make predictions about what you should find based this theory, which can then be falsified.
Dark Matter is falsifiable. That’s probably the most important thing to know about it.
I don’t think neutrinos are usually referred to as dark matter. Dark matter is whatever solves the problem of “What the hell is all the rest of this mass we can only detect gravitationally”, and neutrinos don’t solve that problem. And counting neutrinos as dark matter simply because they aren’t baryons seems a bit silly, seeing as electrons aren’t either.
Rather, I should say, dark matter is whatever solves that problem, subject to the constraint of it being a new type of matter operating essentially as usual under ordinary general relativity. Otherwise I guess it would be unfalsifiable. :) The dark matter hypothesis is really just the “Yes, GR really is correct (at large scales)” hypothesis.
Neutrinos are included in the broad consideration of dark matter because they don’t interact electromagnetically. “Baryonic” and “baryon” aren’t quite the same; baryonic matter only needs to be composed mostly of baryons.
The dark matter hypothesis is really just the “Yes, GR really is correct (at large scales)” hypothesis.
Yes. There’s “dark matter” simply defined as matter that doesn’t participate in the electromagnetic interaction, and then there’s the hypothesis that a significant portion of matter in the universe can be classified as such.
Neutrinos are included in the broad consideration of dark matter because they don’t interact electromagnetically. “Baryonic” and “baryon” aren’t quite the same; baryonic matter only needs to be composed mostly of baryons.
Ah, OK. Wasn’t aware of that distinction. I also failed to notice that the important consideration here is interacts electromagnetically vs. doesn’t. Thanks.
Yes, there are a number of hypothetical non-atomic particles that would need to exist as well, since by their very nature neutrinos have almost no mass. These additional particles have not been discovered, and discovering them would be extremely difficult.
I’d agree that it has the potential to be another phlogiston, but you’ve got to at least give the Dark Matter theorists a chance to falsify their theory. If it becomes a situation where new evidence comes out that DM can’t predict, yet is adapted to describe DM, then you know DM is utter poppycock. There are, however, a number of avenues for experimentation, so it’s certainly not the case that you can call Dark Matter a modern-day phlogiston yet.
At the same time, if DM is poppycock, then GR is necessarily very, very broken (we already know it’s broken, just not for big stuff).
I think you are confused about what dark matter is believed to be.
Dark Matter is believed to be non-baryonic matter. Simple as that. We have direct observations of non-baryonic matter. The largest telescopes in the world are actually designed to detect non-baryonic matter (and they succeed). They have to be buried deep in the earth because it is too easy to get noise from various types of radiation, but this is no problem, because non-baryonic matter doesn’t interact with ordinary matter except in the rarest of situations.
Neutrinos are probably the most well known type of Dark Matter, and those have certainly been directly observed. Scientists are even reasonably certain of the tonnage of neutrinos produced each year by our Sun. There are believed to be other types of Dark Matter, but the nature of the particles make them extremely difficult to study. But not impossible.
The point is that expectations don’t match up with reality, and the only sensible explanation is that the difference is caused by non-baryonic matter (since if it were baryonic, we’d almost certainly be able to see it). You can make predictions about what you should find based this theory, which can then be falsified.
Dark Matter is falsifiable. That’s probably the most important thing to know about it.
I don’t think neutrinos are usually referred to as dark matter. Dark matter is whatever solves the problem of “What the hell is all the rest of this mass we can only detect gravitationally”, and neutrinos don’t solve that problem. And counting neutrinos as dark matter simply because they aren’t baryons seems a bit silly, seeing as electrons aren’t either.
Rather, I should say, dark matter is whatever solves that problem, subject to the constraint of it being a new type of matter operating essentially as usual under ordinary general relativity. Otherwise I guess it would be unfalsifiable. :) The dark matter hypothesis is really just the “Yes, GR really is correct (at large scales)” hypothesis.
Neutrinos are included in the broad consideration of dark matter because they don’t interact electromagnetically. “Baryonic” and “baryon” aren’t quite the same; baryonic matter only needs to be composed mostly of baryons.
Yes. There’s “dark matter” simply defined as matter that doesn’t participate in the electromagnetic interaction, and then there’s the hypothesis that a significant portion of matter in the universe can be classified as such.
Ah, OK. Wasn’t aware of that distinction. I also failed to notice that the important consideration here is interacts electromagnetically vs. doesn’t. Thanks.
Yes, there are a number of hypothetical non-atomic particles that would need to exist as well, since by their very nature neutrinos have almost no mass. These additional particles have not been discovered, and discovering them would be extremely difficult.
I’d agree that it has the potential to be another phlogiston, but you’ve got to at least give the Dark Matter theorists a chance to falsify their theory. If it becomes a situation where new evidence comes out that DM can’t predict, yet is adapted to describe DM, then you know DM is utter poppycock. There are, however, a number of avenues for experimentation, so it’s certainly not the case that you can call Dark Matter a modern-day phlogiston yet.
At the same time, if DM is poppycock, then GR is necessarily very, very broken (we already know it’s broken, just not for big stuff).
I should note, I was not claiming it to be unfalsifiable, I was just picking nits (incorrectly). :P