Arno Penzias, the physicist who detected the echo of the Big Bang, dies

Arno Penzias, the discoverer of the Big Bang echo along with Robert Wilson, died yesterday at the age of 90, in San Francisco, after several years suffering from Alzheimer's.

The physicist, born in Nazi Germany in 1933, ended up in the United States after being evacuated from Europe, like many other Jewish children, in the months before the outbreak of World War II.

His discovery, as sometimes happens in science, came when he and his partner Wilson were looking for something else.

In 1964, they used a sensitive antenna to detect the hydrogen line, a signal with which to understand the structure of the Milky Way.

To capture that weak signal, they had to rule out all types of interference, from poorly insulated cables to pigeon droppings that produced noise in their gigantic antenna.

The strangest of all these interferences was a microwave radio signal that seemed to come from all over the sky, no matter where the antenna was pointed, and which was low in energy.

Arno Penzias (left) and Robert Wilson, in 1993, in front of the Bell Laboratories antenna with which they discovered, in 1964, cosmic background radiation. roger ressmeyer (corbis)

When they were convinced that the signal was real, they discussed their findings with other cosmologists who could make sense of it.

It was Robert Dicke, from Princeton University, who had been trying to capture that signal for some time, who proposed that it was microwave background radiation: a radioactive echo of the big explosion with which it all began.

That observation meant that the idea of ​​the Big Bang, until then a more philosophical than real issue, had experimental verification and prevailed over the idea, very widespread even then, that the cosmos was something stable, that it had always been and always would be.

For that discovery that changed our way of understanding the universe, Penzias and Wilson received the Nobel Prize in Physics in 1978.

“The universe emerges from nothing in an instant and, as an astronomer, I observe that it will continue to expand forever, with a little more matter than antimatter... For reasons we do not understand.

For me the existence of dark matter is not necessary;

“I leave cosmic inflation and things like that to theoretical physicists,” he said in an interview with EL PAÍS 30 years ago, in 1994, three decades after his discovery.

Penzias's discovery is one of the most important in the history of cosmology and one that has most permeated popular culture.

That big bang, which happened almost 14 billion years ago, is a way of explaining the origin of the universe that is attractive to millions of people and has scientific evidence.

What that telescope in New Jersey collected were the radioactive remains of that primeval inflation, and subsequent observations of that phenomenon have allowed, among other things, to know quite precisely the age of the universe and to propose some ideas about what its fate will be.

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