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Common sense - the experience gained from your common everyday experience of reality - does not apply in black holes. Common sense would tell you they can't ex

by XorNot 1mo ago

Common sense - the experience gained from your common everyday experience of reality - does not apply in black holes. Common sense would tell you they can't exist at all because you can't compress atoms - you have lived your entire life with atoms being entirely incompressible for the practical purpose of anything you do. Leaning on common sense to discuss fundamental physics has been wrong since round about the start of the practice of physics.

inigyou 1mo ago
Common sense actually says that atoms don't exist and if you squish cheese really hard you just get really hard and slightly smaller cheese, or maybe you invent a new type of dairy product.
- ben_w 1mo ago
  Dunno, the ancient Greeks had roughly this idea (ἄτομον) in their philosophy, so while actual atomic theory is not common sense, merely having atoms is also not-*not* common sense.
eru 1mo ago
Funnily enough, technical speaking atoms are a small minority of ordinary matter, that is already excluding dark matter. That's because a lot of the ordinary mass in the universe is ionised or in other weirder states.
GoblinSlayer 1mo ago
There's indeed a problem with existence of black holes. Why would they exist? They are usually postulated into existence.
- ben_w 1mo ago
  They're an automatic outcome of fairly benign starting conditions in GR: Simply having more than a certain amount of mass within a certain volume. The required density for that stuff goes down as the volume goes up, so a solar-system sized object (~77 AU radius) at mere normal sea-level (Earth) air density (1.2 kg/m^3) would just be one automatically. Given that the maths of GR requires spacetime to not have a singularity*, and yet it predicts a singularity from benign starting conditions, I take this as a sign that GR is not correct. But black holes are nonetheless an outcome, not a presumption. * it's more complicated than that

by XorNot 1mo ago

inigyou 1mo ago

Common sense actually says that atoms don't exist and if you squish cheese really hard you just get really hard and slightly smaller cheese, or maybe you invent a new type of dairy product.

ben_w 1mo ago
Dunno, the ancient Greeks had roughly this idea (ἄτομον) in their philosophy, so while actual atomic theory is not common sense, merely having atoms is also not-*not* common sense.

eru 1mo ago

Funnily enough, technical speaking atoms are a small minority of ordinary matter, that is already excluding dark matter. That's because a lot of the ordinary mass in the universe is ionised or in other weirder states.

GoblinSlayer 1mo ago

There's indeed a problem with existence of black holes. Why would they exist? They are usually postulated into existence.

ben_w 1mo ago
They're an automatic outcome of fairly benign starting conditions in GR: Simply having more than a certain amount of mass within a certain volume. The required density for that stuff goes down as the volume goes up, so a solar-system sized object (~77 AU radius) at mere normal sea-level (Earth) air density (1.2 kg/m^3) would just be one automatically. Given that the maths of GR requires spacetime to not have a singularity*, and yet it predicts a singularity from benign starting conditions, I take this as a sign that GR is not correct. But black holes are nonetheless an outcome, not a presumption. * it's more complicated than that