The Israeli Scientist Who Taught Stephen Hawking a Thing or Two About Black Holes

Jakob Bekenstein, 1947–2015: The Israel Prize-winning professor did not let his religious faith interfere with his investigations into the secrets of the universe.

Ofer Aderet
Ofer Aderet
Jakob Bekenstein, 2012.
Jakob Bekenstein, 2012.Credit: Emil Salman
Ofer Aderet
Ofer Aderet

His religious faith didn’t stop professor Jacob Bekenstein from the Hebrew University of Jerusalem from investigating the secrets of the universe. “I look at the world as a product of God’s work. He set very specific rules and we get to enjoy the work of scientifically uncovering them – to see how everything integrates together,” said the groundbreaking physicist once.

“Particularly as a kippa-wearer, I’m interested in knowing how nature works. Clearly, things have significance, and I want to understand how to tie things together that seem unrelated. I feel much more comfortable within a world in which I understand why simple things happen. I get a feeling of security, that not everything is random.”

Bekenstein, a recipient of the Israel Prize, the Wolf Prize, the Rothschild Prize and the Einstein Prize, died suddenly of a heart attack this month at age 68. His death came while he was on a lecture tour in Finland. He earned his status as a world renowned physicist by making significant contributions in the fields of astrophysics, cosmology and gravity theory.

Bekenstein was born in 1947 in Mexico City to parents, Yosef and Ester, who had taken refuge there from Poland after World War II. He went to a religious school as a child, but was particularly drawn to subjects like math and chemistry, in order to “know how the world ticks.” He spent his free time experimenting with rockets and was enchanted by the space race that began with the launch of the first satellite in 1957.

Later, he moved to the United States with his parents, and became interested in astronomy. “I spent half the night in dark corners of the neighborhood with a small telescope,” recalled Bekenstein.

From there, the road wasn’t long to studying physics at Brooklyn’s Polytechnic Institute in the mid 1960s. “I learned that if you understand physics, you can understand everyday phenomena. You feel more in control of the world,” he said.

He did his doctoral studies at Princeton University in 1972, writing a thesis that earned him international recognition at age 25. It began with an assignment from his tutor John Wheeler, the man who coined the term “black hole.” “He made me face a contradiction that existed within all perceptions of black holes, and he asked me how to solve the paradox,” Bekenstein recalled.

At the heart of that paradox was a cup of tea. Wheeler wondered what would happen if it was poured into a black hole. According to the second law of thermodynamics, entropy in the universe can never be reduced. At the same time, however, when a black hole swallows something, like a cup of tea, for example, it also swallows that object’s entropy – and the entropy is then supposed to disappear. That would lead to a reduction of entropy in the world, which contradicts scientific principles.

Bekenstein posited that black holes have entropy of their own. “He revolutionized the way we understand the term ‘black hole,’ taking it from esoteric science fiction to objective science,” his son, Dr. Yehonadav Bekenstein, also a physicist, told Haaretz.

His theories, which were against convention, were not accepted straight away. Among his detractors was Stephen Hawking. Just two years later, however, Hawking backed Bekensteins theories and used them as the basis for his own theory, by which black holes supposedly give off radiation.

Motivated by Zionism, Bekenstein moved to Israel in 1974, and began to work at Ben Gurion University. In 1990 he began to work at the Hebrew University in Jerusalem. “I think I’m still doing important things, but it will take more time for the public, and even important scientists, to understand what I did,” said Bekenstein about a decade ago.

In recent years, Bekenstein spent his time trying to alter the theory of relativity in order to make it fit with new astronomic projections. “He developed, along with others, an innovative theory, which doesn’t accept the fact that there is dark matter which we don’t see or can’t measure, which then explains many other things,” said his son.

Bekenstein was aware of the gaps between the importance of his work and the public’s difficulty in understanding it. “It’s a real problem, how to explain what we’re doing in physics to those who need to understand, and the public that pays taxes, basically paying our salaries and the price of our experiments. The problem is that physics is getting farther and farther away from the world that is perceived by eyes and senses, and it’s only going to get worse,” said Bekesintein in an interview with Scientific American Israel.

He explained further: “Our senses are attuned to give us an opportunity to operate with confidence in the everyday world. That doesn’t pertain to the true structure of nature, which is apparently totally different. When physics began to develop, people worked closely to what they saw and felt, and conceptions were very close to what we can understand with our senses. But as we understand more and more, and dig deeper and deeper, we are getting farther away from the world of senses – and it’s going to get worse.”

As an example, he mentioned Newton, whose physics principles were basic in his time. “Balls, moving particles, these things are very close to the senses,” he explained. On the other hand, the situation is totally different today. “Basic principles of physics no longer stem from the senses. They are abstract things, that we don’t think of while examining nature.”

The way to solve this problem, he believed, was to develop the public’s ability to think more abstractly. “It’s not going to work with what goes on in the sink or rolling balls. There won’t be enough there to understand It will be necessary to educate the general public to think more abstractly. There will always be those who can’t do it. But there are some people, including people not within our fields, who can be made to understand,” he said.

Aside from the emphasis he put on abstract thought, Bekenstein believed in using illustrations and demonstrations to explain complex subjects. “They’re always necessary. You must start with something familiar. But it’s a trick. It’s a kind of cheating meant to pull the listener in until they understand the more abstract ideas. Using all kinds of tricks like these is allowed. Good authors do it, too, as do great philosophers. The main issue is that we reach the minimal levels of understanding,” he said.

Bekenstein was aware of the fact that his research was part of a long chain. In 2005, he wrote in Haaretz that “the expression ‘black hole’ sparks the imagination. What’s more interesting than the mystery of something capable of making anything that goes through it, light or matter, disappear? Making it so we cannot peek through? Researching black holes stands at the forefront of science, justifiably, but it also has deep, deep roots.”

He traced these roots to the British scientist John Mitchell in 1783, who believed in the possibility of stars clustered together so tightly that they cannot be seen. Only in the 1970’s did the black hole go from an abstract concept to something observed in nature.

He also had predictions for the future. “In the future, these fascinating ideas will help to solve two significant problems facing humanity,” he wrote. One is the buildup of waste, and the second is the lack of clean, cheap energy sources. “Carefully lowering waste into black holes, with a cable, could power a generator, and generate electricity by turning waste into energy. According to calculations, a ton of waste could provide enough energy for all of humanity for 24 hours. Once enough energy has been created, the waste could then be simply dropped into the black hole.”

Bekenstein is survived by his wife Bilha, his three children, Yehonadav, Uriya and Rivka, and six grandchildren.

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