# [ExI] First Picture of a Black Hole!

spike at rainier66.com spike at rainier66.com
Fri Apr 12 14:21:51 UTC 2019

From: extropy-chat <extropy-chat-bounces at lists.extropy.org> On Behalf Of John Clark
Sent: Friday, April 12, 2019 6:21 AM
To: ExI chat list <extropy-chat at lists.extropy.org>
Subject: Re: [ExI] First Picture of a Black Hole!

On Fri, Apr 12, 2019 at 8:54 AM <spike at rainier66.com <mailto:spike at rainier66.com> > wrote:

>  I don’t see why so much of the material is approximately in one plane.

Actually part of what you're seeing is light from the accretion disk from behind the Black Hole that normally you couldn't see but because of the intense gravity bending light around it you can. For example, the hole in the doenut should be 1.5 times the Schwarzwild radius (because there are no stable orbits between 1 and 1.5) but because of the distortion caused by gravity bending light the hole in the doenut looks to us as if it has a radius of 2.6 times the Schwarzwild radius.

John K Clark

Ja I pondered why that image would look like that and came to these conclusions except without the numbers.  The cool thing about this is that it confirms the math: we can calculate the Schwarzschild radius based on the inner radius of the photo-ring, then do it a second way based on red/blue shifts of the nearby orbiting stars, and see that the mass agrees with the calcs.

Through all this, I am astonished at how much mass is in there.  It also makes me understand why the LIGO results keep coming back with two black holes of the same magnitude rather than a smaller black hole with a biggie.  Reason: the really biggies don’t make that kind of signal when they eat a smaller black hole.

Another reminder of a calc I did some time ago: given a big enough black hole, the event horizon doesn’t have that huge gravitational gradient.  From the point of view of the outside world, an object passing into the event horizon of one of these biggies would disappear into a red (well, very red) whoosh, but from the point of view of the object, not much happened.  Yet.

Hmmm, I might need to retract that notion too: the clock of the object slowed down to nothing as it passes into the event horizon.

Black holes are so cool.

spike

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