Just wanted to take a moment lol..I was going through Google Drive and found some of my old presentations and notes from College... This is an excerpt from my Astrology 101 class presentation notes that had to be turned in after my class presentation on Black Holes. Had to do one of these ever week....Only class I got a B+ in... Can you say he was anal much>? Tonight I will be discussing how black holes were discovered. The first people to have the idea of objects with escape velocities greater than the speed of light, which would be a black hole, were British philosopher John Michell and French Physicist Pierre Laplace in the late 1700’s. This idea was not received well as nobody could really understand it until Einstein published his theory of general relativity in 1915. Now that astronomers had the knowledge to understand four-dimensional space time because of Einstein, a German Physicist named Karl Schwarzschild provided the first exact solution to the Einstein Field Equations of General Relativity in a matter of months after Einstein’s theory of relativity was published. Now the boundary between the inside of a black hole and the universe outside it is called the event horizon. From the outside of a black hole, this event horizon looks like a sphere with a well defined radius that is called the Schwarzschild radius, because Schwarzchild’s solution led to its discovery. More massive black holes have larger schwarzschild radii, as less massive holes have smaller ones, and they retain the gravity associated with that mass. The only way astronomers can detect black holes is by observing their gravities effect on the objects around them, a good example of this would be Cygnus X-1, which is an X-ray Binary system that contains a very luminous star with an estimated mass of 18 solar masses. Based on the doppler shifts of this stars spectral lines, astronomers conclude that this star orbits a compact and unseen object that exceeds the 3 Solar mass Neutron star limit, which means that it Must be a black hole. You can see a figure of this example on page 3.76 figure 13.15.
Posted on: Wed, 28 Aug 2013 20:36:53 +0000
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