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Black hole size could kill general relativity?

Thumbnail for version as of 02:40, 8 September 2006
black hole/Alain r

One can’t get a photo of a black hole but, from Wired:

But thanks to a new telescope, Tim Johannsen, an astrophysicist at the Perimeter Institute and the University of Waterloo in Ontario, Canada, may be able to get a black hole pic after all. A loophole in physics means he might be able to see not the black hole itself, but its shadow. And, no big deal, but that photo just might overturn Albert Einstein’s theory of general relativity.

What’s the loophole?

… when astronomers look at a black hole, what they expect to see is a ring of bright light—the accretion disk—surrounding a circle of nothingness. That circle of nothingness is the shadow. (The black hole itself is just a single point within.)

A model visualization is offered below.

Seen from Earth, the shadow of Sagittarius A*, the supermassive black hole at the center of the Milky Way (also known as Sgr A*, which astrophysicists pronounce “Saj-A-star”) is just 1/35,000,000th the width of the Moon, or 50 microarcseconds wide.

Here’s where that new telescope comes in. Maybe. Johannsen, Broderick, and their colleagues hope the Event Horizon Telescope will be able to resolve Sgr A*’s shadow. The EHT is actually nine telescopes (and counting)…

And Einstein’s general relativity theory?

The problem is, general relativity is really good at describing giant things like stars, but breaks down utterly when it comes to really teeny tiny things like photons and quarks. To talk about those, you need a different theory: quantum mechanics. More.

In short, they seem to be hoping that the actual black hole is so small that general relativity cannot predict its behaviour. Interesting approach. Lots of people have tried to overturn Einstein’s theories, of course.

See also: General Relativity still beautiful, ahead of its time?


PBS asks, Must we rewrite general relativity?

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We don't need black holes to kill GR. GR is dead because it is based on the following assumptions: 1. The universe is deterministic. Wrong. 2. The universe is continuous. Wronger. 3. There is a time dimension. Not even wrong. 4. There is a space out there. Stupid is as stupid does. 5. The universe is local. Fail. 6. Gravity travels at the speed of light. Major fail. There is more but these will do. GR is just modern Ptolemaic epicycles. Mapou

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