this post was submitted on 16 Mar 2025
1 points (100.0% liked)

science

17139 readers
128 users here now

A community to post scientific articles, news, and civil discussion.

rule #1: be kind

<--- rules currently under construction, see current pinned post.

2024-11-11

founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 0 points 2 days ago* (last edited 2 days ago) (8 children)

Steffen Gielen, Lucía Menéndez-Pidal.
Black Hole Singularity Resolution in Unimodular Gravity from Unitarity
Physical Review Letters, 2025; 134 (10)
DOI: 10.1103/PhysRevLett.134.101501

i can't even understand the very beginning of the discussion : why are physicists so obsessed with "information loss" ?

It has long been stated that a quantum theory of black hole dynamics that is required to be unitary must deviate strongly from semiclassical expectations. Usually this is discussed in the context of unitarity of black hole formation and evaporation, leading to the famous issue of information loss.[24]*

[24]* : S. W. Hawking, Breakdown of predictability in gravitational collapse
Phys. Rev. D 14, 2460 (1976).

[–] [email protected] 0 points 2 days ago (7 children)

To oversimplify, "information" is a very specific thing in quantum physics. Classical physics has the rule that energy can change form but cannot either be created or destroyed.

Information works the same way in quantum physics, which makes black holes seem like a problem since their event horizons are inescapable and anything that falls inside is lost.

[–] [email protected] 0 points 2 days ago (1 children)

why's it a problem? why can't information just be lost at a black hole?

[–] [email protected] 0 points 2 days ago (1 children)

The problem is that it'd be like if matter and energy could just disappear. Black holes would be exclusively tiny, as soon as one formed it'd start vanishing anything that crossed it's event horizon rather than growing, so galaxies could never have formed as their cores would just shrink away as soon as they got too dense.

Black holes are regions of space where information density hits the upper limits allowed by physics. Add more information to it, and the event horizon expands proportionally to what was added. With that in hindsight, it seems rather obvious that the boundary of the event horizon could encode the information once thought to be lost to the black hole inside.

[–] [email protected] 0 points 2 days ago (1 children)

It could do that but what's the evidence that it does? Or has someone proved this is already a feature of semi-classical gravity that just wasn't noticed before? Or is it only a feature of a brand new hypothetical theory?

[–] [email protected] 1 points 1 day ago* (last edited 11 hours ago)

How deep do you want to go into this, and what's your level of familiarity with the Holographic Principal and AdS/CFT corrospondance? There's no hard evidence yet but there is a shitton of circumstantial evidence to suggest that this is what happens.

load more comments (5 replies)
load more comments (5 replies)