When the Big Bang was just a theory

CREATIVE LIGHTS
George Gamow, Fred Hoyle and the Big Bang Debate
By Paul Halpern

The universe is changing. But scientists didn’t realize it a century ago, when astronomers like Edwin Hubble and Henrietta Leavitt discerned that other galaxies existed and that they were moving away from the Milky Way at incredible speeds. This monumental discovery sparked decades of epic debates over the vastness and origins of the universe, and they involved a clash of titans, Russian-American nuclear physicist George Gamow and British astrophysicist Fred Hoyle.

In his new book, “Flashs of Creation,” Paul Halpern chronicles Gamow and Hoyle’s rise to leaders of mostly opposing views on cosmology, as they argued whether it all started with a Big Bang. billions of years ago.

Halpern, himself a physicist at the University of the Sciences in Philadelphia, skillfully sheds light on their fascinating stories, out of the shadow of the overlapping quantum physics debates between Albert Einstein and Niels Bohr, about which Halpern wrote in a previous book. Halpern also asks fundamental questions about how science should be done. When do you decide, for example, to abandon a theory? Ultimately, his book seeks to justify Hoyle, who in his later years did not admit that his idea was lost.

Until the arrival of these two daring theorists, astrophysics was stuck at a dead end. Scientists did not know how to interpret Hubble’s observations, and no one understood how the universe created and constructed chemical elements. “It is clear that the intuitive and intuitive styles shared by Gamow and Hoyle were absolutely necessary in their time,” writes Halpern.

Gamow and Hoyle make for a difficult “joint biography,” Halpern acknowledges, in part because their side histories have so rarely intersected. They had only one important meeting in person, in the summer of 1956 in La Jolla, Calif., Where Gamow had briefly served as a consultant for General Dynamics, the aerospace and defense company. They discussed many ideas in this coastal town, hanging out in Gamow’s white Cadillac, but for the most part their debates took place in the pages of physics journals, newspapers, and magazines, including Scientific American.

They also frequently appeared in early television and radio shows, becoming among the first well-known science communicators, paving the way for Carl Sagan, Neil deGrasse Tyson, Bill Nye, Carolyn Porco, Pamela Gay and others today. . Hoyle wrote the sci-fi novel “The Black Cloud” and the television script “A for Andromeda”, while Gamow produced “One, Two, Three… Infinity” and the Mr. Tompkins series, including character struggles. principal illustrated aspects of modern science.

For years, their dueling theories – a Big Bang origin of matter and energy (defended by Gamow) versus a stationary state universe that created matter and energy by quantum fluctuations (defended by Hoyle) – have remained highly speculative. Initially, the Big Bang theory predicted a universe only a few billion years old, which conflicted with observations of the sun and other stars, known to be much older. Physicists were also divided between the two.

But that changed as more and more evidence emerged and a key finding finally seemed to settle the debate. In 1964, astronomers Arno Penzias and Robert Wilson noticed a constant static radio signal with the Holmdel Horn antenna in New Jersey. After ruling out possible experimental sources of noise (including pigeons and their droppings on the antenna), they deduced that the radio whistle had a cosmic origin. They and their colleagues finally realized that the signal came from relic radiation from the hot fireball of the early universe.

After that, the Big Bang theory quickly became a consensus in the field. While Hoyle’s idea of ​​steady state ultimately failed, he made many other important contributions, particularly involving stellar processes and supernova explosions, which he said could fuse chemical elements into heavier atoms and produce nitrogen, oxygen, carbon and more. In explaining this, and throughout the book, Halpern provides many useful metaphors and analogies. He also reminds readers that Hoyle, Gamow, and their fellow theoretical physicists made these achievements long before the heyday of supercomputers.

Halpern is not afraid of character flaws. In particular, it shows how Hoyle’s later life work sided with physics, including his controversial “panspermia” hypothesis, that organic matter and even life on Earth came from the collision of comets. , and his unsuccessful attempts to revive the steady state theory. But that shouldn’t throw a veil on his legacy.

Hoyle’s investment in theory raises important philosophical and sociological questions about when we should consider a proven idea. It is also the kind of dilemma that creeps into contemporary debates among physicists: about dark matter versus modified theories of gravity; on what dark energy is and how the universe’s “inflation” occurred moments after the Big Bang; and about a persistent gap in the measurements of the rate of expansion of the universe, known as the “Hubble voltage”. Unfortunately, Halpern only briefly mentions these active research areas, which owe a lot to Gamow and Hoyle.

At one point in the book, Halpern recounts a conversation he had with Geoff Burbidge, a colleague of Hoyle who also continued to support a steady-state model. Cosmology needed alternatives, he argued, not lemmings following their leader over a cliff.