Posted by Davin Flateau on 10 Feb 2006 at 12:06 pm.
Filed under General, Astronomy.
This is the second 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 2
In the first part of our history of black holes, we covered an amazing 228 years in the development of physics, from Newton’s first mathematical description of gravity in 1687, to Swartzchild’s work in 1915 defining how a black hole would behave in Einstein’s new wonderful world of gravitation, space and light.
The 1920s and 30s were the golden age of physics. Almost every year new discoveries about the atom, radiation and astronomy forced us to rethink the Rules of the Universe as we knew them. And just when we’d finish putting the jigsaw puzzle together, another new discovery would be published, scattering the pieces again into the wind. With each new picture of how the Universe worked, the theories about black holes stayed alive, growing and morphing. It wasn’t long until black holes were the closest thing to “The Twilight Zone” scientists had ever seen on paper. A place where light couldn’t escape? What happens at the center of the black hole, where time and space came to a “point”? Normal physics would cease to exist there. It didn’t make sense to many astronomers, and it sure wasn’t pretty. How could nature, humming with the harmonious warm glow of trillions of suns, produce something so ugly and contradictory as black holes?
But the idea kept popping up. If you have something that goes very fast, like light, could it be trapped by an object with a huge amount of gravity? Schwarzchild’s answer was yes.
Up to this point, and for some time afterwards, the history of black holes was a history of an idea. No one had ever looked for one in the real Universe, nor did many people think they they actually existed. Until about 1930.
Dateline: 1930 The middle of Indian Ocean. Subrahmanyan Chandrasekhar (Chandra), a 19-year old Indian undergraduate student on his way to study in England, decides to pass the time on the ocean voyage thinking about white dwarfs. No, not the bearded gnomes, but the stars. He figured out that there was a limit to how massive white dwarfs can get. White dwarfs are what’s left over when a star collapses - the tiny, compressed burnt out cinder of the star it once was. He found that anything that small could only have a mass of about 1.45 times the mass of our sun. If the remnant was any more massive than that — very weird things would start to happen It would become unstable, and collapse onto itself, resulting in an object that no one could really explain.
Dateline: 1930, England. Enter one of the most visible enemies of the black hole theory: Arthur Eddington. He was an expert in relativity - a leading astrophysicist, and made strong statements against the existence of black holes, especially Chandra’s theories. Unfortunately, he was arguing against someone who would go one to be called the greatest mathematical astrophysicist of all time. The debate between the established giant and the young upstart only served to strengthen the theory that black holes might come about in the real world.
Dateline: 1967, New Jersey. American physics giant John Wheeler invents the term “black hole” to describe what might happen if an object collapsed on itself gravitationally. Wheeler was working on trying to come up with explanations of rapidly rotating pulsars, another fate of a dying star. But in explaining all the possibilities of a star’s funeral, Wheeler had to coin some kind of neat phrase to explain the weird phenomenon of “gravitationally collapsed objects”. The name stuck. Once skeptical of black holes, Wheeler found important definitions of how these objects could really form in nature. Wheeler helped figure out that a star more massive than two of our suns is too large to form a neutron star or a white dwarf when it runs out of fuel. A collapsing star larger than that would keep collapsing, shrinking into a quantum abyss that would give birth to a new black hole.
Dateline: 1973, Oxford, England. At the height of his powers, Steven Hawking is focused into the world of black holes. He wasn’t just concerned about how they were born - he went much farther into their lives. Hawking showed that during the big bang, tiny black holes could litter the Universe. Could they get larger? Yes. Could they break apart? No. Do black holes eventually die? Hawking showed that small black holes formed during the Big Bang can evaporate — slowly leaking energy, and therefore mass — over billions of years — until they explode. With the his famous 1988 book and 1991 film, A Brief History of Time, he made black holes a household name. The strange and bizarre world that the wheelchair-bound Hawking described captured the imagination of popular culture, making him the most famous scientist alive today.
Next Up: Black Hole in a Bird?
