Nobel Prizes Go to Caltech Chemist, Dutch Physicists
Caltech chemist Ahmed H. Zewail won the Nobel Prize for chemistry Tuesday for finding a way to freeze-frame the private matings of molecules using ultra-fast laser probes, a technique with the potential to revolutionize everything from dentistry to microelectronics.
Billions of times more fleeting than the blink of an eye, Zewail’s “femtosecond” flash camera captures real-time movies of molecules as they meet, mate and “divorce,” in Zewail’s terms--bringing into focus events that previously zoomed by in an unfocused blur.
“It’s opened up a world of chemistry in motion,” said Cornell University Nobel laureate Roald Hoffmann.
The physics prize was awarded to Gerardus ‘t Hooft and Martinus J.G. Veltman of the Netherlands for the invention of precision mathematical tools that make it possible to calculate the properties of fundamental particles.
“All calculations having to do with modern particle theory rest on their work as the rock bottom foundation,” said mathematician and physicist Brian Greene of Columbia University.
Among other things, the new math tools led indirectly to the prediction--accurately confirmed about five years ago at the Fermi National Accelerator Laboratory--of the mass of a fundamental particle called the top quark.
In keeping with his work, Zewail said he was “frozen in time” when he heard the news. Caltech President David Baltimore--himself a laureate in biology--praised Zewail’s work at a morning news conference as “monumental. He’s the first person to look at the making and breaking of chemical bonds.”
Then Baltimore gave Zewail exactly “one minute and a half” to describe his work. Zewail didn’t blink. “In femtoseconds, it’s [a lot],” he said. At a mere one-millionth of one-billionth of a second, a femtosecond is to a second what a second is to 32 million years.
In essence, Zewail uses elaborate nets of multicolored lasers to snare molecules in the act of moving together, bonding and breaking apart. All life--in fact all matter more complicated than atoms--is based on such interactions. And before Zewail perfected his technique, it all happened invisibly.
“Ahmed’s experiments allow us to see these processes directly,” said Caltech chemist Jacqueline Barton, who is using Zewail’s technique to track the motion of electrons as they travel through DNA. “He’s done outstanding science,” she said. “[His contribution] is huge.”
Already, Zewail has stumbled upon surprises in this molecular underworld. For example, the twisting of a protein in the eye in response to light that makes vision possible happens much faster than anyone had thought. It takes just 200 femtoseconds for the protein to complete its reaction and send the signal on to the brain.
“Nature did not want to take the energy from the sun and waste it,” Zewail said, “so the time scale is very short.”
Even the simple reaction between sodium and chlorine that forms ordinary table salt turned out to be unexpectedly rich, he said.
“They love and hate each other about 10 times before they break the bonds and divorce,” he said.
Said by some to be the Sigmund Freud of chemistry, Zewail frequently refers to molecules in such anthropomorphic terms. “Why not?” he asked. “Love and hate. We find this in molecules too.”
Caltech was ready for the honor: It has been expecting Zewail to win the prize for several years. “It’s a great relief,” said Baltimore.
Zewail didn’t rest well Monday night. “I didn’t want to put myself up for disappointment,” he said. “You can never be sure with a Nobel Prize.”
In the near future, Zewail plans to return to his native Egypt--which has already issued a stamp in his honor--to celebrate further. He intends to devote some of the $960,000 in prize money to the high school he attended in Alexandria, which also carries his name.
Although, as a young researcher, he never expected such a call from Stockholm, Zewail said, he always had a passion for science. As a child, he set fires under test tubes to turn various solids into gas.
“My mother said I was going to burn down the house,” he said.
His passion is still to understand fundamental processes. “I love molecules,” he said. “I want to understand why do they do what they do.”
Yet his work has enormous practical potential in virtually every corner of chemistry. For example, femtosecond lasers now being introduced into dentistry can drill a hole so fast that the heat doesn’t have time to dissipate into the patient and cause pain. Eventually, the technique could illuminate understanding of how drugs work and aid in designing medicines. “We have dreams . . . ,” Zewail said wistfully.
Femtochemistry made visible the many intermediate steps that take place during a chemical reaction--way stations that make the reaction possible. Fathoming these links in the chain enables chemists to both understand and perhaps control reactions with much greater precision than previously possible.
“If you can understand the landscape of chemical change, then you can change that landscape,” Zewail said. “We are entering new fields which we never dreamed of.”
His work, said the Nobel citation from the Swedish Royal Academy, “brought out a revolution in chemistry and adjacent sciences.”
The physics prize once again underscored the critical role of mathematical tools in discoveries about the physical world.
“The arsenal of the theoretical physicist consists of mathematical tools for describing nature,” said Columbia’s Greene. “[‘T Hooft and Veltman] supplied us with a wonderful set of sharp tools.”
Specifically, the men were able to tame certain out-of-control aspects of an otherwise promising theory of fundamental particles and forces. The theories described the nature of the connection between electromagnetism and the so-called “weak” force involved in nuclear burning and radioactivity.
Although the theory had been “written down, it didn’t make sense,” said physicist Edward Witten of the Institute for Advanced Studies at Princeton, who is visiting Caltech this year and joined Zewail’s celebration. “People didn’t know whether to take it seriously.”
Like other theories of subatomic particles, the electro-weak theory was riddled with what UCLA physicist Roberto Peccei called “diseases” that made it useless. Calculations using the theory produced infinite answers. Infinite answers, in physics, are nonsense.
The mathematical tools developed by the two laureates made it possible to eliminate the infinities in certain circumstances.
“Before their work, there were certain things we didn’t think we could calculate,” Peccei said. The two Dutch scientists “showed you could. And [the theory] gave you the right answers.”
Even more important, Peccei explained, the refined calculations made possible with the new tools revealed subtle aspects of particle interactions not previously evident. An understanding of these interactions led to the accurate prediction of the mass of the newly discovered top quark--the last member of the family of elementary particles to be discovered.
These tools are also helping physicists refine their search for the most wanted particle in physics today, the so-called Higgs boson, thought to endow particles with mass.
For this reason, said Peccei, the finding was “extraordinarily important. [This Nobel is] about as well-deserved as an award can be.”
Praising ‘T Hooft, he added: “There are two kinds of geniuses: ordinary geniuses and magicians. ‘T Hooft is the second kind. He is one of the deepest people in the world.”
* CALTECH MENTOR HAILED
Caltech faculty and students hailed recognition for Ahmed Zewail, saying it’s overdue. B1
