Black Hole Formation Sequence: Time in the Equations?

[Funestis]

Hello all,

To my knowledge, there are still a lot of questions regarding the specifics of black hole formation. My question is in regards to formation time. I've read that the actual formation takes "less than a second" according to the equations. Does anyone know where time shows up in the black hole formation equations or where this statement derives from? I'm not familiar with the specifics of the black hole formation sequence but if anyone has any resources I'd be grateful for them.

Many thanks!

 

[PeterDonis]

I've read

Where? Please give a specific reference.

 

[Funestis]

Neglecting the less than reputable sources (like Yahoo answers), here:

http://chandra.harvard.edu/resources/faq/black_hole/bhole-33.html

Here:

https://www.universetoday.com/116465/how-quickly-do-black-holes-form/

 

[Nugatory]

Try googling for "Oppenheimer Snyder Solution"; this is the solution of the equations of general relativity for an idealized gravitational collapse.

 

[PeterDonis]

Neglecting the less than reputable sources (like Yahoo answers), here

These are still not textbooks or peer-reviewed papers, which are the sources you need to look at if you want to understand the actual physics involved. The short answer is that the times quoted in those articles are how long the collapse would take according to a clock carried by an observer riding on the surface of the collapsing matter. But to see how that works out in the math, you need to look at the Oppenheimer-Snyder solution, as Nugatory suggested. This solution is discussed in MTW; I don't know if other GR textbooks go into detail about it.

 

[Funestis]

That's exactly what I was looking for, thank you guys!