1989 Balzan Prize for High Energy Astrophysics
Acceptance Speech – Bern, 17.11.1989
Ladies and Gentlemen:
I should like to express gratitude for the honour done to me by this award; and for the recognition of “high energy astrophysics”, a subject which itself hardly existed before the 1960s.
The last two decades have been a unique period of cosmic discovery. Not only has our own Solar System being explored with spaceprobes, but x-ray, infrared and radio techniques have been deployed to complement what is learnt from optical telescopes. There have been many surprises. The cosmic scene is more violent and complex than most astronomers imagined.
It was my good fortune to start my research career when the results began to come thick and fast, and theorists were being challenged to interpret them.
The observers and experimenters are the real heroes of these endeavours. Theorists like myself have explained rather little, and predicted still less.
We can observe objects so far away that their light has taken billions of years on its journey towards us. But our present map of the cosmos is an incomplete and tentative one. Early cosmographers, when they mapped the Earth, populated the boundaries of the then-known world with mythical beasts. We, likewise, have discerned remote wonders in the heavens, and cannot be sure that our theories are adequate to describe them.
High energy astrophysicists work at the interface between physics and astronomy. Exotic cosmic phenomena — quasars, black holes and the big bang — involve more extreme physics than ordinary stars. Astronomical observations can test or extend the established physical laws, and perhaps discover new ones.
It’s not surprising, in a changing subject with such ambitious scope, that we are still groping for understanding. On the contrary, what’s really astonishing is that any progress is possible. As Einstein said “the most incomprehensible thing about the Universe is that it is comprehensible”. It is remarkable that any of the laws established in the laboratory — laws that our minds are somehow attuned to understand — should govern the atoms in a remote quasar or in the big bang itself.
The Universe has a simpler overall pattern than we have any right to expect; there is a deep interdependence between the micro-world of subnuclear particles and the cosmos as a whole.
The technical advances in our subject are owed to a worldwide scientific community. As individual projects become more challenging, international collaboration has become essential.
A subject so seemingly remote from practical concerns would — to me, at least — be less appealing if interest didn’t percolate beyond the specialists. But the essential issues are accessible, even if the technicalities are not. A broad public participates vicariously in our exploration of the cosmos; the origin and fate of the Universe, and our place in it, fascinate all those of philosophical disposition.
It’s a platitude — but no less true for that — that the first view of the entire Earth from space had a psychological impact on the world’s people, and stimulated concern about its fragile biosphere. High energy astrophysics now teaches us to see the entire cosmos as a unity. The physical laws that govern our everyday world were “imprinted” in the initial instants of the big bang. Each carbon and oxygen atom in our bodies was forged in some ancient star which exploded, somewhere in the Milky Way, before our Solar System formed.
Charles Darwin concluded his “Origin of Species” with these famous words: “Whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most wonderful have been, and are being, evolved”.
Astrophysicists aim to trace things back before Darwin’s “simple beginning” — to set the entire Solar System in an evolutionary context stretching right back to the initial! instants of the amorphous “fireball” with which our entire Universe began. As it expanded and cooled, myriad galaxies condensed — each a swarm of billions of stars. And on a planet around at least one star, creatures evolved able to wonder about it all.
Our emergence has taken several billion years. But the Universe has run less than half its course, and may even have an infinite future ahead of it. So it is presumptious to view humanity as the culmination of evolution. Even if the Earth is now a tiny oasis in an inanimate cosmos, over the vast timespan that lies ahead it could “seed” the spread of life through the entire Galaxy and beyond. To snuff out our biosphere now could be a genuinely “cosmic” disaster in terms of the potentialities it would foreclose.
I’m indebted to many friends whose world-lines have meshed with mine: Dennis Sciama, who kindled my enthusiasm for astrophysics; my scientific collaborators, especially Roger Blandford, Mitchell Begelman, Andrew Fabian and James Pringle; and my colleagues, especially Donald Lynden-Bell, who make Cambridge such a stimulating place to work.
Finally, let me reiterate my sincerest thanks to the Balzan Foundation for recognizing and encouraging our efforts to understand our cosmic environment. This is a collaborative enterprise, an unending quest that has barely begun.