Posted by Davin Flateau on 7 Feb 2006 at 5:22 pm.
Filed under General.
This is the first article in a series about black holes, in conjunction with the release of the new Black Holes CyberDome show at Exploration Place on February 17.
The History of Black Holes, Part 1
Every child in school learns about the basics of the scientific method: observation, hypothesis and experiment hopefully leading to some kind of conclusion. The story of black holes is a perfect example of how science can be a remarkably powerful vehicle for taking an interesting notion down the road to a profound discovery and realization. Black holes began as an hypothesis, a bizarre mathematical quirk born in paper and ink that would lead to huge mountain-based and orbiting telescopes searching the depths of the Universe for invisible objects. The conclusion so far? Black holes are not only the strange and elusive objects we originally thought, but are also supermassive anchors of entire galaxies, including our own Milky Way.
Black Holes are all about gravity - it’s their defining quality. Mars may be the Red Planet and stars may shine brilliantly and give off heat, but black holes don’t have any of that going for them. For these enigmas, it’s all about the pull.
Dateline: 1678, England. Isaac Newton described the idea of gravity in 1687, giving us the first mathematical tools to predict how gravity worked. But it took almost 100 years for the first known reference to a “black” object to come forth.
Dateline: 1783, England. English geologist John Michell had an idea that there might be an object that is so massive, that the speed required for anything to leave its surface (often called escape velocity) would be so great so that nothing — not even light travelling at 186,000 miles an hour — could ever escape its surface. Michell called these objects “dark stars” because anyone who would be looking at them would see nothing. A dark void hanging against the blackness of space would truly be invisible. Thirteen years later, the great French mathematician and scientist Pierre LaPlace put forth similar ideas.
Keep in mind that at this point, “dark stars” were all theoretical conjecture. No one had ever seen them through a telescope, nor did they even look for one. Black holes were just ideas set to the music of mathematics; a thought experiment using the cutting-edge thinking of the time.
Dateline: Early 1800s. The idea of black holes fell away in the 1800s. Light was discovered to be a wave of energy, so the previous idea that it was a particle of some mass - and therefore affected by gravity - went out of style (this would later prove to be too simplistic). So the new scientific mental picture of a “dark star” freed the light from its imaginary jail on the surface, and the most massive stars could once again shine on. The “dark star” idea seemed about as physically possible as a flying pig.
Dateline: 1915, Berlin. A young superstar physicist with a neatly trimmed mustache and tightly cropped black hair publishes a series of papers on the nature of space, time and gravity that would revolutionize how we saw the Universe. Albert Einstein’s General Theory of Relativity was the crowning achievement in a 10-year run of papers that changed everything. The General Theory of Relativity told us that the space in the Universe was actually bent by gravity. The theory also goes on to say that light travelling through that space would also follow the same curve, in essence bending the light. If light could be bent by gravity, could it be trapped? Thw answer came within weeks, but from a very unexpected place.
Dateline: 1915, the Russian Front, World War I. A middle-aged man with less hair and a much bushier mustache seizes on Einstien’s work. Accomplished astronomer turned volunteer soldier Karl Schwarzschild writes to Einstein, showing him how to use the recent equations to explain how space warps around a massive object, particularly around a “point mass” or singularity. Schwarzschild has proven that black holes can exist in theory. He dies just months after his letters to Einstein, and is remembered today in part by having a defining characteristic of Black Holes named after him: The Schwarzschild Radius. For black holes, this radius represents the famous “point of no return” from where no light, matter, or information of any kind can emerge. In a coincidence for the ages, Schwarzschild’s name in German translates out to “Black Shield.”
Tomorrow: The plot thickens! The theories get sophisticated, and the search begins!
gerad couts on 3 May 2007 at 9:28 am: 1
HELP ME