4 ms·
> Heretofore every observation of perturbances has correctly presaged the presence of a large mass (a planet) that was quickly found, but this time we have look
by yongjik 4y ago
> Heretofore every observation of perturbances has correctly presaged the presence of a large mass (a planet) that was quickly found, but this time we have looked and looked but not found anything. Should we presume that it must be an invisible ball of matter that gravitates but we have no other way of detecting except through the same effect we use to infer its existence, or should we tweak Newton's laws of physics?
Note the leap of faith from "a large planet" to "an invisible ball of matter." As one could imagine, given what we knew in the 19th century, "a small, hard-to-observe planet (or a group of small bodies) orbiting very close to the sun" was a totally reasonable hypothesis. "An invisible ball of matter" wasn't (and still isn't). It was natural that physicists never seriously considered such a possibility.
On the other hand, given what we know now, "a diffuse cloud made of particles that do not interact with light" is a totally reasonable hypothesis. In fact we even know one such "invisible" particle: neutrinos. It's not crazy to assume that there are some other kinds of neutrino-like particles that fit the bill.
- atoav 4y agoI mean a primordial black hole with the size of a tennis ball would have 5 to 15 earth masses. It would not be invisible, but at that size it would be invisible to us even if it was in our solar vicinity. If primordial black holes are things that exist, one could reason that they might be an explaination for masses we cannot see maybe?
- simonh 4y agoIt's an interesting idea. I suspect such a large population of these objects would generate enough x-rays from interactions with dust and gas that we'd be able to detect their presence. We'd also probably see micro-lensing of various observable phenomena if they were that populous. Just guesses though.
- rini17 4y agoAstronomers searched for microlensing events from black holes or similar dark objects, but did not see so many.
- gpderetta 4y agoIndeed black holes and other dark stars are a reasonable option for dark matter [1], but apparently observations do not seem to match this model adequately. [1] they are collectively called MACHOs, as opposed to WIMPs...
- naasking 4y ago> On the other hand, given what we know now, "a diffuse cloud made of particles that do not interact with light" is a totally reasonable hypothesis. Was a reasonable hypothesis. Given the evidence so far, it's now very debatable. Just like another planet was a reasonable initial hypothesis until it wasn't.