Hawking Describes Black Holes

There was plenty of room to stretch out in Sanders Theatre yesterday, as renowned physicist Stephen W. Hawking described the mathematical underpinnings of black holes in his second of three Loeb lectures.

Sanders Theatre was filled to capacity during the first lecture on Monday, and tickets for all three lectures sold out within an hour of when they went on sale at the Harvard Box Office.

Perhaps because of the technical focus of yesterday's lecture, though, a steady trickle of students began heading for the door after Hawking dove into topics like path integrals in 11 dimensions, leaving the theatre only partially full by the end of his speech.

"I was kind of disappointed that so many people got up and walked out," said Anna C. Gay '02. "I think they couldn't understand it."

But Hawking had warned audience members that the technical details of yesterday's lecture--which included a mathematical conjecture that the universe is a four-dimensional surface sandwiched between two five-dimensional regions--might elude them.

"The important thing is that you'll get the flavor of the formula for black hole entropy" rather than understand all the equations, Hawking said.

Hawking's speech concerned the nature of infinitely dense cosmic objects called "singularities," which are found at the center of black holes.

Black holes are formed when massive stars, having exhausted their nuclear fuel, collapse under the weight of their own gravity until they become so dense that nothing that enters their sphere of influence can escape--even light.

Since time stops at the center of a black hole, matter and information that fall into it are gone, forever frozen while the universe continues around the singularity.

"A singularity signals the end of time for the matter contained within it," Hawking said.

It is in these singularities, Hawking continued, that the normally disparate theories governing quantum mechanics and gravity could find common ground. The study of singularities is therefore crucial to any attempt to unify all the forces of nature into one, large "Theory of Everything,"

Unfortunately, this project is complicated by the fact that singularities have not been found outside of black holes, which makes them difficult to study.

" God must have thought that [the existence of naked singularities] would make things too easy for theoretical physicists, so he exercised a form of cosmic censorship," Hawking joked.

However, Hawking said his discovery that black holes radiate heat, and are therefore slowly evaporating, means that they are not completely "black" after all, so their elusive secrets might soon become more accessible.

Students said that some of the theories that Hawking expounded--that the universe was really made up of 10 or 11 tightly wound dimensions, for example--seemed almost inconceivable.

"This is quite a fascinating world that [physicists] have constructed. It boggles the mind," Gay said.

Although she understood few of Hawking's mathematical demonstrations, Avra C. Van der Zee '02, who is also a Crimson editor, said she thought seeing Hawking in person was fulfilling enough.

"What was amazing to me was just watching him talk, realizing that this man has equations in his head right now," she said.