Occasional postings will comment on news relating to Einstein’s ideas. This introduction explains my interest.
About Einstein’s Universe
“Let’s make relativity plain,” was my answer when BBC-TV in London and WGBH in Boston asked, in 1978, how we should celebrate the centenary of Albert Einstein’s birth in the following year. Not just Special Relativity, high-speed travel and E=mc2. Those are fairly easy to talk about. General Relativity (GR), Einstein’s theory of gravity, was the challenging task.
What spurred me were memories of struggling as a student with GR, taught at Cambridge as a branch of higher mathematics. Also irritation at being told again and again that GR was beyond the grasp of ordinary mortals, six decades after our Albert dreamed it up. He was an intuitive physicist and not a brilliant mathematician. Those fancy equations were supplied by other people. So what were the pictures in his head?
Months of fun followed, in the course of which Martin Freeth, producer-director for the BBC, borrowed the McDonald Observatory in Texas and brought to it the eminent physicists and astronomers who were to explain Einstein’s ideas to a genuine layman. This was the actor Peter Ustinov, who also spoke Einstein’s own words and twice acted the part of a time traveller. Specially made for the programme and flown out from London was a billiard table configured so that a ball representing a planet could orbit in the warped space around the Sun, or fall into a black hole.
The difficulty about GR was silly. The theory’s beauty is that it saves the Universe from the mayhem that would result if the speed of light in empty space were able to change – for a start, atoms would behave differently. “The velocity of light never varies” became a mantra of the theorists dealing with GR and its inscrutable mathematics, to make clear what was necessary to keep the cosmos safe.
But in the late 1960s radar experiments by Irwin Shapiro of MIT showed that radio pulses going to and from Venus or Mercury were delayed when those planets were passing across the far side of the Sun. The radio waves, an invisible form of light travelling in the near-vacuum of interplanetary space, slowed down as they grazed the Sun and felt its gravity.
For atoms in the Sun’s atmosphere the radio waves still seemed to be travelling at the correct speed. Why? Because time passes more slowly in the Sun’s strong gravity than it does for radar physicists on the less massive Earth. The velocity of light measured locally never changes, but it can certainly appear to do so for a distant onlooker.
Perhaps the most useful thing I ever did as a science writer was to persuade the distinguished Oxford theorist Roger Penrose to own up to all this, on prime-time television. As he said:
Gravity has the apparent effect of reducing the speed of light and slowing down time. So if you imagined the extreme situation of a black hole, then light would be reduced to zero speed, apparently, and time would apparently have been stopped completely at the surface.
Say that, and GR is quite easy to understand without mathematics. And it gives a mechanism for gravity, which Isaac Newton’s less exact theory never did. On the Earth, gravity is slightly weaker for an apple hanging from a tree than for the same apple fallen to the ground. A little nearer to the planet’s centre of mass, time and light both travel a little more slowly, so the fallen apple has less inherent energy. Where did the energy go? It went first into the energy of downward motion, then into a bruising thud.
You can’t mess with time and with the speed of light without deforming space. A mass enlarges distances in its vicinity, as judged by the time taken for light to traverse them, so space becomes baggy and curved. When a planet tries to travel in a straight line across the bag created by Sun’s gravity, the curvature forces it to stay in orbit. As the billiard table illustrated the mechanism, our éminence grise, John Archibald Wheeler from Austin, Texas, put the point succinctly to Peter Ustinov:
Matter tells space how to curve. Space tells matter how to move.
‘Einstein’s Universe’, a 120-minute TV film produced and directed by Martin Freeth for the BBC and WGBH, was presented by Peter Ustinov, and written by Nigel Calder. First broadcast on the centenary of Einstein’s birth, 14 March 1979, it is still shown, although only very occasionally – most recently, if memory serves, in Hungary in 2009.
The book that accompanied the programme has been a bit more durable. Einstein’s Universe by Nigel Calder was published by the BBC in London and Viking in New York on the day of the broadcast. The journal Nature greeted it as “a valuable contribution to the demystification of relativity” and, commenting for lay readers, the Evening Standard said it was “consistently illuminating” and the Irish Times called it “a must”.
Paperback editions and translations followed and the book has remained in print ever since. Penguin Books, which had first published the paperback Einstein’s Universe: The Layman’s Guide in 1982 decided to reissue it as Einstein’s Universe: The Layperson’s Guide in 2005, for the centenary of the 26-year-old Albert’s “miraculous year” of several early discoveries.
After a quarter of a century, did the book need updating? You bet, but not perhaps in the way you might think. Of the 21 chapters, 20 remained unchanged. All that was wrong was the last chapter, entitled Einstein’s Successor. “The time seems ripe,” I wrote in the original, “for another genius to succeed him as he succeeded Newton and Maxwell.” But no, physics at that level has simply stalled for many years. If this reporter goofed, so did an entire generation of bright young theorists.
In the late 1970s, weren’t they crouched on the blocks for their next leap forward? They were going to unify two great theories, by taming GR, General Relativity, to conform with QM, Quantum Mechanics. The way to do it was by no glorious simplification in the Einsteinian manner but by theories of mind-boggling complexity, as “supersymmetry” evolved into “superstrings” in ever-increasing numbers of dimensions of space.
Not for the first time, a scientific consensus has run its sterile course, in my opinion. The theories turn out to be “All hat and no cattle” as they’d say in Marfa, West Texas, whose real-life cowboys joined us for a fireworks party when we filmed “Einstein’s Universe”. Luckily some much better stories were available for Afterword 2005: The Melting Pot, which replaces the outdated Einstein’s Successor in the new edition of the book. They include:
- A verdict against Einstein in his battle with quantum mechanics, when an implication he dismissed as “spooky action at a distance” turned out to be observable experimentally, in 1982.
- Confirmation of the reality of black holes, by the ASCA satellite in 1994.
- A verdict for Einstein in his prediction that atoms could club together at very low temperatures, when the first “Bose-Einstein condensates” were made in 1995.
- The unexpected discovery in 1998 that the expansion of the Universe is accelerating, an option always implicit in Einstein’s cosmological equation of 1917.
- The gradual realization that a far-flung spacecraft, Pioneer 10, tracked from 1972 to 2003, dawdled on its way out of the Solar System, as if held back more strongly than expected by the tug of the Sun. As the only strong observational hint so far that GR may not be perfect, it’s just the kind of discrepancy that our Albert relished.
You can buy Einstein’s Universe: A Layperson’s Guide at:
You can by a DVD of the film at http://www.amazon.com/Einsteins-Universe-Peter-Ustinov/dp/B000PKUU3W
And you can buy Albert Einstein: The Special and the General Theory
– a re-issue by Penguin Classics, also for the Einstein Year 2005, of the maestro’s own early explanation for non-experts, with high-school maths. Nigel Calder wrote an explanatory introduction.