Erin Hoey. Black holes.

I watched “Andrea Ghez: The Hunt for a Supermassive Black Hole.” She talks about how there are three describable characteristics of a black hole: the mass, the spin, and the charge. But, she only talks about the mass in this TED talk. Black holes are extremely difficult to study because you cannot see them; their gravitational pull is so strong that not even light can escape it. Therefore, black holes are the absence of light. They are truly invisible. Black holes are objects that have a mass of 0. They have no finite size. Yet, they can be “supermassive.” The Schwarzschild radius the size of any object that is so small that gravity takes over and it keeps collapsing in on itself. For example, the Schwarzschild radius of the earth is a sugar cube. If a star bigger than the sun explodes, it creates supernova dust-like remnants that surround a black hole, about three times the mass of the sun. That’s a small black hole on the scale of the universe. Galaxies are composed of stars. The light that makes up the galaxy we see comes from these stars. However, some galaxies emanate an energy that cannot be explained by stars. Some people believe that this light is caused from the energy given off by a black hole pulling so strongly mass into its center. This theory has given rise to the thought that all galaxies have black holes at their centers, but some are smaller than others. In order to see if this is true, we have begun studying the center of our own Milky Way galaxy, because it is the closest galaxy center to our planet. We can seethe center in greater detail than we could other galaxies. If a black hole existed in the center, the stars would orbit around it, just like planets orbit the stars. The bigger the black hole, the faster and tighter the orbit. To see if a black hole really exists in the center, studies need to be made of the radius and speed of the orbits of the stars closest to the center. So, big telescopes need to be used. The biggest telescope on earth is in the Keck Observatory, with a mirror diameter of 10 meters. Since the atmosphere is continuously moving, distorting the telescope pictures, adaptive mirrors must be put in that move and change with the atmosphere in order to get a clearer picture. These adaptive mirrors have improved the pictures by a factor of 20. The star SO-2 is the closet we can see with our telescopes to the center of our galaxy, with an orbit of just 15 years, compared to our sun’s orbit of 200-million years. After watching this star, it is believed that the Schwarzschild radius of our galaxy is the size of our solar system. However, this is just over what our galaxy, a mass 4-billion times that of our sun, would actually be if computed numerically. But, it is the only evidence we have, and from observations of SO-2, it seems to be the only truth we have. Since there is believed to be a supermassive black hole at the center of our galaxy based on these observations, there should be a cluster of old stars near the center, since new stars cannot form in the hostile environment near a black hole. However, at the center of our galaxy, there is a cluster of new stars. How are there new stars at the center of the galaxy near this supermassive black hole? This is a really big mystery, one that Andrea Ghez is still uncovering today.

I watched this TED talk because space is interesting to me. It is so big and there is so much we don’t know about it. Black holes are even more interesting, because they could destroy everything, and are believed to be what will eventually swallow up are entire universe, only to explode in a big bang and create a new one all over again. I was interested to see how they search for black holes, and thought that this talk would teach me more about them.

Ghez studied at the Massachusetts Institute of Technology and received a BS in physics in 1987, and at the California Institute of Technology received her Ph.D. She is now an astronomer and professor at UCLA in the Department of Physics and Astronomy. In 2004, she was elected into the National Academy of Sciences.

Next year, I will be attending Phillips Academy at Andover, a boarding high school in Andover, Massachusetts, for a post-graduate year. It is arguably the best high school in the country. There, I can take astronomy and a variety of physics classes, which is one of my favorite subjects at school. I can take some time to decide what I want to do. Like Ghez, I will probably major in physics, or something science-related. I want to go far with my education so that I can have a variety of jobs available to me once I end school. Right now, space exploration is what is looking very appealing to me, since new technology is being developed every day. Maybe I’ll even be an astronaut.