Scientific Serendipity

Serendipity means you're looking for one thing, but find something else. Throughout the history of science there are numerous examples of just such fortuitous occurrences. One of the best illustrations of how scientific serendipity can change the world occurred back in 1964, when the first cries of our baby Universe were luckily heard--by chance! It was in that year that Dr. Arno Penzias and Dr. Robert W. Wilson at the Murray Hill facility of Bell Telephone Laboratories in New Jersey noticed a mysterious and inexplicable "noise" coming from their new radio antenna. They later found that what they were, in fact, picking up with their radio dish was the first solid proof that the Universe was born in the Big Bang. Penzias and Wilson were noticing the first whispers of the Cosmic Microwave Background (CMB) radiation, stretched out to exceedingly long electromagnetic wavelengths due to the expansion of the Universe. As it turns out, anyone can bear witness to the relics of our Universe's birth. If you tune your television set between channels, some of the "snow" that appears on your screen is actually "noise" caused by the CMB radiation.

The CMB radiation is a faint glowing light that fills the entire Cosmos, falling on our little blue planet from all directions with almost unvarying intensity. It is the heat left over from the beginning of our Universe almost 14 billion years ago; the afterglow of the Big Bang. This ancient light whispers to us some very wonderful secrets about an extremely remote epoch that existed long before there were any observers around to witness it first-hand. The CMB is the most ancient light that we can see--it has been traveling to us from the greatest distance that we can observe in Space and Time. This light began its long journey almost 14 billion years ago, and this was billions of years before our planet, our Solar System, or even our ancient Galaxy, the Milky Way, existed. It tells of a vanished, extremely remote time when all that existed was a writhing storm of fire-bedazzling radiation and a raging sea of elementary particles--hardly the relatively quiet and frigid dark place that we know now. The familiar objects that we observe in our Universe at present--the glittering incandescent stars, enchanting planets and moons, and even the majestic galaxies --eventually congealed from these newborn particles, and the Universe expanded and dramatically cooled off.

This precious, glowing relic of our Universe's infancy is a little gift, of sorts, to observers on Earth today. This is because it carries the fossil imprint of those ancient particles--a pattern of exquisitely tiny intensity variations from which scientists can figure out the attributes of the Cosmos.

When the CMB began its long journey billions of years ago, it shone as brightly as the surface of a star, and it was just as hot. However, the expansion of the Universe stretched Space a thousand-fold since then, causing the wavelength of that ancient light to be stretched, as well--to the microwave portion of the electromagnetic spectrum. The temperature today of that once searing-hot light is a truly frigid 2.73 degrees above absolute zero!

The late Dr. Carl Sagan of Cornell University wrote in his book Cosmos (1993): "As space stretched, the matter and energy in the universe expanded with it, and rapidly cooled. The radiation of the cosmic fireball, which... filled the universe, moved through the spectrum--from gamma-rays to X-rays to ultraviolet light; through the rainbow colors of the visible spectrum; into the infrared and radio regions. The remnants of the fireball, the cosmic background radiation, emanating from all parts of the sky can be detected by radio telescopes today. In the early universe, space was brilliantly illuminated. As time passed, the fabric of space continued to expand, the radiation cooled and, in ordinary visible light, for the first time space became dark, as it is today."

George Gamow, Ralph Alpher, and Robert Herman were the first cosmologists to predict the existence of the CMB in 1948. Alpher and Herman estimated that the temperature of the CMB would be approximately what we now know it to be.

Because the 1948 estimates were not widely discussed in scientific circles, they were rediscovered by Dr. Robert Dicke of Princeton University and the renowned Soviet astrophysicist Dr. Yakov Zel'dovich in the early 1960s. The first published study that discussed the CMB radiation as a possibly detectable entity in astrophysics was authored by two Soviet astrophysicists, Dr. A.G. Doroshkevich and Dr. Igor Novikov, in early 1964. Also in that year, Dr. David Todd Wilkinson and Dr. Peter Roll, who were Dicke's colleagues at Princeton University, began assembling a Dicke Radiometer. In fact, it was a Dicke Radiometer that Penzias and Wilson had built, and were attempting to use for radio astronomy studies of our Milky Way Galaxy and satellite communications experiments, before it started to emit that mysterious "noise". Adding to this delightful little comedy, at around the same time, Dicke,Wilkinson, and Dr. P.J.E Peebles, a mere 37 miles away at Princeton, were preparing to search for the CMB in precisely the same region of the electromagnetic spectrum in which the befuddled Penzias and Wilson were picking up that bizarre and mysterious "noise". Penzias and Wilson were unaware of the new work on the CMB, even though much of it was being performed near them at Princeton. There were also a lot of pigeons at Murray Hill--many of them roosting near the new radio dish. At first, Penzias and Wilson believed that the bizarre and pesty "noise" was caused by pigeon droppings. The pigeons were unceremoniously evicted from their radio dish, and their droppings were dutifully wiped away--but the "noise" persisted. It was low and steady--and very persistent. This residual "noise" was 100 times more intense than Penzias and Wilson had expected and was evenly spread across the entire sky, and it was always there--both day and night! It could not be coming from the Earth, the Sun, or even the Milky Way Galaxy. The rest is history.

The instrument at Bell Labs had an excess antenna temperature which Penzias and Wilson could not explain, and that mysterious "noise" was apparently coming from beyond our Galaxy! Their yelps of exasperation, at long last, reached Dicke. After Dicke had received a telephone call from Murray Hill, he made what is now one of the most famous (and funniest) remarks in the history of science. Dicke turned to his colleagues and said: "We've been scooped!" Penzias and Wilson did not find what they were looking for--they found something else. They found the Cosmic Microwave Background radiation, the first strong piece of observational evidence that our Universe had a definite beginning, billions and billions of years ago, in the Big Bang. Peebles had just written a paper discussing the possibility of finding the CMB, and when Penzias and Wilson became aware of this, they finally began to realize the great significance of their serendipitous discovery. The characteristics of the "noise" that Penzias and Wilson had picked up with their radio antenna fit exactly the radiation predicted by Dicke and his colleagues at Princeton. A subsequent meeting between the Murray Hill and Princeton teams reached the historic conclusion that the mysterious antenna temperature was indeed being caused by the long-sought and elusive light dancing to Earth since the beginning of Time--the CMB radiation. Penzias and Wilson received the 1978 Nobel Prize in Physics for their serendipitous discovery.

As Dr. John C. Mather and Dr. John Boslough wrote in their book The Very First Light (1996): "Had Arno Penzias and Robert Wilson known in 1964 of the prediction of Alpher and Herman sixteen years earlier, the two Bell scientists would have been spared a year's work trying to uncover the source of the noise in their horn antenna. Had [Robert] Dicke been aware of the prediction, he could have begun work on his own antenna years earlier without having to wait."

Almost 14 billion years ago, something mysterious and wonderful occurred--the Big Bang birth of our Universe, accompanied by a very brief episode of exponential expansion termed inflation. Why our Universe came into being in that magnificent event is the greatest mystery of all; the greatest mystery that we can ever know. All of the energy and matter that now exist in the Universe was at that first instant concentrated at extraordinarily high density--perhaps into a mathematical point that had no dimensions whatsoever. It is incorrect to imagine that all of the energy and matter in existence was then crumbled and squeezed tightly into a infinitesimal ball, sequestered in a tiny corner of the Universe that we now know. Imagine, instead, the entire Universe, energy and matter, as well as the space they fill, occupying an unimaginably minute volume.

In that great initial explosion, the Universe commenced an expansion that has never ended--and may never end. The CMB is now very cold, shining primarily in the microwave portion of the electromagnetic spectrum. As such, it is invisible to our human eyes. If we could see microwaves, the entire sky would glow with a haunting and lovely brightness, amazingly uniform in all directions. By studying this ancient light, emitted long before there were stars or galaxies, astronomers can begin to understand the conditions in the Universe on very large scales at very ancient times.