Black Holes: Observational Evidence Slide 18 of 24

Here we see a picture taken by the Hubble Space telescope a few years ago. It shows a (supposed) black hole at the center of a distant galaxy. This black hole was formed by the gravitational collapse of 500 million stars which all converged at the center of the galaxy. The central disc is 400 light years across. This is a distance equivalent to how far light would travel in 400 years. To get a feeling for how big this is, consider that the speed of light is about one billion kilometers an hour. Now try to imagine how far light would get in one year. The distance across the center of this galaxy is 400 times greater. Although the scale of this galactic black hole is very different from the artist's rendition on the previous slide, the general features are the same: stars seem to be swirling around a very dense black hole at the center of the galaxy before being sucked down the drain. There is in fact strong evidence that huge black holes like this exist at the center of most galaxies, including around own. So black holes appear to exist. Now on to Hawking's attempt at synthesis, and the resulting discord.

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