B Can Curving a Space-Cone Create a Black Hole?

  • B
  • Thread starter Thread starter swampwiz
  • Start date Start date
swampwiz
Messages
567
Reaction score
83
require so much energy that the density of the energy - i.e., its mass equivalent - must always create a black hole? I was watching a video by Sean Carroll describe how this is *theoretically* possible, but obviously catastrophic.
 
Physics news on Phys.org
Please provide a link to the video and a timestamp for where Carroll talks about this. Better yet, a paper or textbook reference. Without a reference it's difficult to tell if you are describing something I understand but using unusual terminology, or describing something I can't help with.
 
  • Like
Likes Dale
Here is where he discusses it:

 
That's an hour long video. If you meant it to start somewhere in the middle, it didn't work. Can you give me a time stamp?
 
Try 38:05.
 
Carroll seems to be talking about spacetimes containing closed timelike curves. I don't think we know a way to create them, even in principle. They are pre-existing features of some spacetimes.

As far as I'm aware, it's a case of "can't get there from here". We can describe spacetimes containing CTCs. We can describe our spacetime. We don't know a way to describe something that starts looking like our universe but later on has a CTC in it. It may well be impossible to do so.
 

Thread 'A sufficient condition for integrability of equation ##\nabla g=0##'

In Philippe G. Ciarlet's book 'An introduction to differential geometry', He gives the integrability conditions of the differential equations like this: $$ \partial_{i} F_{lj}=L^p_{ij} F_{lp},\,\,\,F_{ij}(x_0)=F^0_{ij}. $$ The integrability conditions for the existence of a global solution ##F_{lj}## is: $$ R^i_{jkl}\equiv\partial_k L^i_{jl}-\partial_l L^i_{jk}+L^h_{jl} L^i_{hk}-L^h_{jk} L^i_{hl}=0 $$ Then from the equation: $$\nabla_b e_a= \Gamma^c_{ab} e_c$$ Using cartesian basis ## e_I...
View full post »
Thread 'Dirac's integral for the energy-momentum of the gravitational field'

Thread 'Dirac's integral for the energy-momentum of the gravitational field'

See Dirac's brief treatment of the energy-momentum pseudo-tensor in the attached picture. Dirac is presumably integrating eq. (31.2) over the 4D "hypercylinder" defined by ##T_1 \le x^0 \le T_2## and ##\mathbf{|x|} \le R##, where ##R## is sufficiently large to include all the matter-energy fields in the system. Then \begin{align} 0 &= \int_V \left[ ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g}\, \right]_{,\nu} d^4 x = \int_{\partial V} ({t_\mu}^\nu + T_\mu^\nu)\sqrt{-g} \, dS_\nu \nonumber\\ &= \left(...
View full post »

Thread 'Hawking After 54 Years Confirmed: BH surfaces don't shrink'

Abstract The gravitational-wave signal GW250114 was observed by the two LIGO detectors with a network matched-filter signal-to-noise ratio of 80. The signal was emitted by the coalescence of two black holes with near-equal masses ## m_1=33.6_{-0.8}^{+1.2} M_{⊙} ## and ## m_2=32.2_{-1. 3}^{+0.8} M_{⊙}##, and small spins ##\chi_{1,2}\leq 0.26 ## (90% credibility) and negligible eccentricity ##e⁢\leq 0.03.## Postmerger data excluding the peak region are consistent with the dominant quadrupolar...
View full post »

Similar threads

B Formation of a black hole using acceleration
Replies
14
Views
2K
B Can Relativistic Mass Create a Black Hole?
Replies
4
Views
2K
B A question about quarks and black holes
Replies
12
Views
2K
B Hawking Radiation and Shrinking Black Holes
Replies
12
Views
4K
B Creating Artificial Black Hole: Force Requirements
Replies
11
Views
1K
B How do Black Holes Grow? A Far-Away Observer's Perspective
2
Replies
67
Views
5K
B Question about the Entropy of a Black Hole Singularity
Replies
17
Views
3K
B Theories about light and time near a black hole
Replies
20
Views
2K
I Can We Confine Energy to Create Microscopic Black Holes?
Replies
2
Views
1K
B Gravitons: Relationship to Space-Time & Black Holes
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top