ThE hIddEN REALITY <strong>Columbia</strong> CollEgE Today to absolute zero, placing their frequencies in the microwave part of the spectrum. For this reason, they are called the cosmic microwave background radiation. i recently reread the papers of Gamow, Alpher, and Herman that in the late 1940s announced and explained these conclusions. They are marvels of theoretical physics. The technical analyses involved require hardly more than a grounding in undergraduate physics, and yet the results are profound. The authors concluded that we are all immersed in a bath of photons, a cosmic heirloom bequeathed to us by the universe’s fiery birth. With that buildup, you may find it surprising that the papers were ignored. This was mostly because they were written during an era dominated by quantum and nuclear physics. Cosmology had yet to make its mark as a quantitative science, so the physics culture was less receptive to what seemed like fringe theoretical studies. To some degree, the papers also languished because of Gamow’s unusually playful style (he once modified the authorship of a paper he was writing with Alpher to include his friend the future Nobel laureate Hans Bethe, just to make the paper’s byline — Alpher, Bethe, Gamow — sound like the first three letters of the Greek alphabet), which resulted in some physicists taking him less seriously than he deserved. Try as they might, Gamow, Alpher, and Herman could not interest anyone in their results, let alone persuade astronomers to devote the significant ef<strong>for</strong>t required to attempt to detect the relic radiation they predicted. The papers were quickly <strong>for</strong>gotten. In the early 1960s, unaware of the earlier work, the Princeton physicists Robert Dicke and Jim Peebles went down a similar path and also realized that the big bang’s legacy should be the presence of a ubiquitous background radiation filling space. Unlike the members of Gamow’s team, however, Dicke was a renowned experimentalist and so didn’t need to persuade anyone to seek the radiation observationally. He could do it himself. Together with his students David Wilkinson and Peter Roll, Dicke devised an experimental scheme to capture some of the big bang’s vestigial photons. But be<strong>for</strong>e the Princeton researchers could put their plan to the test, they received one of the most famous telephone calls in the history of science. While Dicke and Peebles had been calculating, the physicists Arno Penzias and Robert Wilson at Bell Labs, less than thirty miles from Princeton, had been struggling with a radio communications antenna (coincidentally, it was based on a design Dicke had come up with in the 1940s). No matter what adjustments they made, the antenna hissed with a steady, unavoidable background noise. Penzias and Wilson were convinced that something was wrong with their equipment. But then came a serendipitous chain of conversations. It began with a talk Peebles gave in February 1965 at Johns Hopkins <strong>University</strong>, which was attended by the Carnegie Institution radio astronomer Kenneth Turner, who mentioned the results he heard Peebles present to his MIT colleague Bernard Burke, who happened to be in touch with Penzias at Bell Labs. Hearing of the Princeton research, the Bell Labs team realized that their antenna was hissing <strong>for</strong> good reason: it was picking up the cosmic microwave background radiation. Penzias and Wilson called Dicke, who quickly confirmed that they had unintentionally tapped into the reverberation of the big bang. The two groups agreed to publish their papers simultaneously in the prestigious Astrophysical Journal. The Princeton group discussed their theory of the background radiation’s cosmological origin, while the Bell Labs team reported, in the most conservative of language and with no mention of cosmology, the detection of uni<strong>for</strong>m microwave radiation permeating space. Neither paper mentioned the earlier work of Gamow, Alpher, and Herman. For their discovery, Penzias and Wilson were awarded the 1978 Nobel Prize in physics. Gamow, Alpher, and Herman were deeply dismayed, and in the years that followed struggled mightily to have their work recognized. Only gradually and belatedly has the physics community saluted their primary role in this monumental discovery. ThE unCanny uni<strong>for</strong>miTy of anCiEnT PhoTons during the decades since it was first observed, the cosmic microwave background radiation has become a crucial tool in cosmo- logical investigations. The reason is clear. In a great many fields, researchers would give their eyeteeth to have an unfettered, direct glimpse of the past. Instead, they generally have to piece together a view of remote conditions on the basis of evidence from remnants — weathered fossils, decaying parchments, or mummified remains. Cosmology is the one field in which we can actually witness history. The pinpoints of starlight we can see with the naked eye are streams of photons that have been traveling toward us <strong>for</strong> a few years or a few thousand. The light from more distant objects, captured by powerful telescopes, has been traveling toward us far longer, sometimes <strong>for</strong> billions of years. When you look at such ancient light, you are seeing — literally — ancient times. Those primeval comings and goings transpired far away, but the apparent large-scale uni<strong>for</strong>mity of the universe argues strongly that what was happening there was also, on average, happening here. the pinpoints of starlight we can see with the naked eye are streams of photons that have been traveling toward us <strong>for</strong> a few years or a few thousand. MAY/JUNE 2011 36 In looking up, we are looking back. The cosmic microwave photons allow us to make the most of this opportunity. No matter how technology may improve, the microwave photons are the oldest we can hope to see, because their elder brethren were trapped by the foggy conditions that prevailed during earlier epochs. When we examine the cosmic microwave background photons, we are glimpsing how things were nearly 14 billion years ago. Calculations show that today there are about 400 million of these cosmic microwave photons racing through every cubic meter of space. Although our eyes can’t see them, an old-fashioned television set can. About 1 percent of the snow on a television that’s been disconnected from the cable signal and tuned to a station that’s ceased broadcasting is due to reception of the big bang’s photons. It’s a curious thought. The very same airwaves that carry reruns of All in the Family and The Honeymooners are infused with some of the universe’s oldest fossils, photons communicating a drama that played out when the cosmos was but a few hundred thousand years old. To watch Brian Greene talk about his work, go to college.columbia.edu/cct. Excerpted from The Hidden Reality by Brian Greene. Copyright © 2011 by Brian Greene. Reprinted with permission by Alfred A. Knopf, a division of Random House, Inc. All rights reserved.
<strong>Columbia</strong> CollEgE Today ThE hIddEN REALITY alumni news MAY/JUNE 2011 37 38 Bookshelf 40 obituaries 43 Class notes 80 alumni Corner PhOTO: EILEEN BARROSO
Change language