3 ms·
The simplest explanation is that there is regular matter which we fail to detect. Not weird, given the huge distances involved - there almost assuredly is mass
by Beldin 4y ago
The simplest explanation is that there is regular matter which we fail to detect. Not weird, given the huge distances involved - there almost assuredly is mass that we didn't detect (e.g. planets).
The point where fairy matter comes in, is that we can guess how bad we could be at not detecting matter. Basically, regular matter that we didn't observe can't explain everything - we would've observed it otherwise.
- bmitc 4y ago> The simplest explanation is that there is regular matter which we fail to detect. Not weird, given the huge distances involved - there almost assuredly is mass that we didn't detect (e.g. planets). What is the difference between that and dark matter? > there almost assuredly is mass that we didn't detect (e.g. planets). Don’t planets give off light and thus contribute to the distribution of light observed?
- mr_mitm 4y agoThe GP is talking about MACHOs; MAssive Compact Halo Objects. They used to be a valid DM candidate but have been ruled out 20-30 years ago. Planets don't give off any non-negligible amount of light. However, they do consist of baryons (read: atoms) which would contribute to the baryonic accoustic oscillations in the CMB power spectrum, so that's a good probe to set upper limits on baryonic matter in general. Primordial black holes are a somewhat related candidate; but those are mostly considered ruled out as well. They are not considered baryonic matter.
- throwawaymaths 4y agoSorry, There are currently hard constraints on the lumpiness and size on that matter which basically exclude all reasonable possibilities for "normal matter we fail to detect". It's certainly possible something strange is happening though, or our statistics could be wrong.
- ndsipa_pomu 4y agoThat's not the simplest explanation as our current theories limit the amount of normal matter that can exist and galaxies behave gravitationally as though there must be a lot more than normal matter. Normal matter that is invisible to us is not a viable solution to the evidence. There some discussion of regular (baryonic) matter vs dark matter here: https://www.livescience.com/how-much-dark-matter-universe https://www.livescience.com/how-much-dark-matter-universe