Christian Long

Andrea Ghez: The Hunt for a Supermassive Black Hole

In TED Talks on April 26, 2010 at 4:15 pm

Reflection by BENEDIKT K.

Original TED page w/ speaker bio, links, comments, etc:

Andrea Ghez: The Hunt for a Supermassive Black Hole

Black holes are some of the most curious and most fascinating objects in existence.

One of humanities oldest dreams was to fly like a bird, and once this had been accomplished to find what is outside of the air that we breathe. So the notion of an object that no bird, no human, not even light can escape comes with interesting implications. But black holes are, as Mrs. Ghez explains, not necessarily extremely massive objects.

The mathematically simplest black hole is that with infinitely small mass. This is due to the phnomenon we call gravity, in praticular the existence of something called the schwarzschild radius. The schwarzschild radius is, simply put, the blackness that you see when you look at the accretion disk of a black hole. It is the only visual you have of the black hole itself. t is, however, also the radius in which the mass of the black hole will collapse to a singularity, an entity with a mass that is confirmed to a volume of zero. this is what causes the hole to be black, as any light that enters this sphere cannot escape anymore and is eventually sucked into the middle. Interestingly, the schwarzschild radius increases in a fashion directly proportional to the mass of the object. What this means is that the black hole needn’t be significantly dense, as the volume of a sphere increases in relation to the cube of the radius, while density is inversely proportional to the first power of the volume, causing some supermassive black holes to be about as dense as the air around us.

But since this schwarzschild radius permits no light out of its system, we cannot observe a black hole directly. However, also due to the schwarzschild radius, all we need to know is the mass of an object to find whether it is a black hole. By now, through the calculation of stars and other massive objects close to the center of the universe, where a supermassive black hole is assumed to reside, astronomers have found that a mass of 4 million suns must be confined to an area of about our solar system. While this is still slightly, in relative terms, above the schwarzschild radius of such a mass, it is close enough as that no other possibility we know of could provide an answer for this phenomenon, letting us assume that there is in fact a supermassive black hole in the center of the galaxy.

Interestingly however, most assumptions made by scientists about what this black hole should produce, in terms of effects, are constantly being disproven by actual data. The creation of larger telescopes for higher detail, and development of more methods to decrease the effect of the earths atmosphere on the astronomical data may be able to provide better methods of observation, and as the technology industry flourishes, it may be quite soon that this black hole is completely confirmed, and that others are found.


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