20 points dverlaeckt80 1 hour ago 12 comments

rustyhancock 1 hour ago | parent

One of the most remarkable aspects of physics is that Newtonian gravity calculations are quite spot on for all the parts of black holes layfolk consider important.

1. Both predict the same critical radius, now called the Schwarzschild radius.

2. Both predict a central singularity with formally infinite density in idealised collapse.

3. Both predict exactly the same finite time to fall into the singularity under equivalent idealised conditions.

4. Both give the same equation for radial free fall, using different definitions of time.

What GR added was meaning to these things (and of course precise calculations outside of very idealised scenarios and symmetric conditions).

ant6n 23 minutes ago | parent

Newtonian gravity gives infinite time to fall into black hole?

I thought you need at least special relativity for time dilution.

JohnKemeny 1 hour ago | parent

Is it just me, or could they have added a, say, picture of a black hole?

bcraven 29 minutes ago | parent

It's the one in your head that you picture, as not many have been taken:

https://www.si.edu/newsdesk/releases/astronomers-reveal-firs...

lifestyleguru 13 minutes ago | parent

I remember times when the best available photo of Pluto looked like this.

GreenLightGo 3 minutes ago | parent

Why does it look like it's moving to me?

ButlerianJihad 27 minutes ago | parent

This is a transcript of a 60-minute podcast. Would you like that TIFF in Zmodem format? Or they could read it out in base64?

myrmidon 46 minutes ago | parent

What I find really interesting is that black holes don't really "require" infinite density; the mass density inside the event horizon never exceeds neutron star levels, and becomes in fact lower the heavier the black hole gets (=> event horizon enclosed volume grows faster than mass).

monster_truck 42 minutes ago | parent

I'd use a camera, personally

jareklupinski 35 minutes ago | parent

make sure you set the exposure to a negative value

b3lvedere 25 minutes ago | parent

f/0 should work ? :)

spottedmarley 27 minutes ago | parent

First you'll need a camera that can detect mathematical equations.