830K views · May 1, 2021 · 11:50 · 2 HN recommenders · 4 mentions · discussed 2021–2023
Sabine Hossenfelder explains how her opinion on dark matter has shifted, weighing the evidence for and against it and the case for modified gravity. It runs through what dark matter is and why it has not been detected.
Why Hacker News points people here: Recommended as an accessible, curious-undergraduate-level overview of dark matter and its alternatives.
“Here’s Sabine Hossenfelder’s curious-undergraduate-level history of Dark Matter theories”HN comment, 2023
“Sabine is a great science (physics) communicator to the "masses", she recently did an update on dark matter.”
Sabine's recent update on dark matter.
Sabine is a great science (physics) communicator to the "masses", she recently did an update on dark matter. this video
“Here’s Sabine Hossenfelder’s curious-undergraduate-level history of Dark Matter theories”
Accessible history of dark matter theories.
> correct me if I’m wrong … I think you’re oversimplifying, like seeing a forest and overlooking that it’s Prototaxites, not Malus domestica. Here’s Sabine Hossenfelder’s curious-undergraduate-level history of Dark Matter theories: this video Proper nouns include Renzo’s Rule and Baryonic Tully Fisher Relation.
“Also worth pointing out that dark matter is not the only explanation”
I am not an expert. My understanding - (1) The quantity of rocks that would be needed to explain such a gigantic gap in mass is bound to be observed - if they are dark, then at least we should be able to see them when they block light. You have to remember we need dark matter to be around 80% of total mass of the universe. So they either need to be super dense, like tiny black holes [1], or there needs to be so much of it that there is no way we won't see them. (2) Dark matter is too spread out. If they were rocks or any of the known matter types, they should have coalesced on their own. So they have to be such that dark matter doesn't interact with itself. Edit: This is a nice intro: link Edit 2: Also worth pointing out that dark matter is not the only explanation: this video [1] link
They're "actually" what QFT says they are, but the rest isn't wrong either. It's not wrong to say "a house exists" because it's actually a pile of bricks in the shape of a house. Dark matter must be "matter" if it exists, because there's not a category of things that aren't matter. this video
