A Tribute To Freeman Dyson On His 90th Birthday
Freeman Dyson, one of the world’s most eminent theoretical physicists, recently celebrated his 90th birthday. Born in England on 15 December 1923, Freeman Dyson graduated from Cambridge University in 1945 with a BA in mathematics. In 1947, he moved to the USA where he went to work at Cornell University and, later, at the Institute for Advanced Study in Princeton. Professor Dyson is a member of the GWPF’s Academic Advisory Council. On the occasion of his 90th birthday, we republish an CCNet-interview he gave Benny Peiser in March 2007.
Benny Peiser: Let me start with your essay, “Sir Phillip Robert’s Erolunar Collision,” that you wrote in 1933, aged 9. Your first ever piece of science fiction, a story about asteroid Eros, is very charming from a historical perspective. Eros plays a significant role in the history of modern astronomy. It was the first discovered near Earth asteroid and, with a size of circa 13 x 13 x 30 km, is the second largest known NEO. Evidently, your narrative about the asteroid’s close approach was written in the aftermath of the Eros fly by in 1930/31.
What I find intriguing in your account is the conspicuous cheerfulness of the astronomers. When the fictitious president of the astronomical society, Sir Phillip Roberts, announced that Eros may one day collide with the Earth, the reaction of his fellow astronomers is enthusiastic: “Three cheers for Eros!” and “Hip, Hip! Hurrah! They all shouted.” After more calculations revealed that Eros would collide with the Moon in as little as 11 years, the astronomical society decided to organise an expedition to the Moon so that they would witness the collision in situ, “instead of through a telescope.”
It would appear that the perception of a collision by a large asteroid with the Earth was still regarded as something of a challenge rather than a global catastrophe. Today, we know that the impact of an asteroid the size of Eros would wipe out more than 90{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} of all terrestrial forms of life. This, then, raises the following questions: Why was the potentially existential threat at the time of your writing greatly underestimated? Looking back at your own intellectual development, when did you yourself begin to realise the severity of the threat posed by asteroids and comets?
Freeman Dyson: Certainly as a nine-year-old I considered the Erolunar collision as a great lark and did not worry about the dangers. That is the normal reaction of nine-year-olds to adventures of all kinds. I remember an excellent film called Hope and Glory‘ portraying World War Two as seen through the eyes of a nine-year-old kid in England. For the kid, the war was a great lark. That was true. That film gave the most accurate picture of the war that I have seen.
To me it came as a complete and wonderful surprise when Luis Alvarez discovered the iridium layer that showed a connection between the dinosaur extinction and an extraterrestrial impact. There was no doubt that the two events occurred at the same time, and that many species of plankton in the ocean became extinct at the same time too. And still, I was always skeptical of Alvarez’s theory explaining how the impact caused the extinctions. And I am still skeptical. We now know that the other major extinctions do not have iridium layers associated with them, and we know that the dinosaur extinction has a major volcanic eruption (Deccan Traps) associated with it. So it is plausible that volcanic eruptions are the main cause of extinctions, with extraterrestrial impacts giving an additional push if they happen to occur at the same time.
After looking at the evidence, I do not agree with your statement, “we know that an impact of an asteroid the size of Eros would wipe out more than 90{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} of all terrestrial forms of life”. I would say that this statement is an exaggeration, similar to statements of the same kind that are made about global warming. Certainly the danger from asteroid impacts is real, and certainly it makes sense to study ways of deflecting asteroids when the opportunity arises. But I find much of the rhetoric about asteroid impacts to be exaggerated. It seems likely that the real dangers to the survival of the biosphere come more from inside the earth than from outside.