Infinity and beyond

Black holes are a source of mystery for Gary Day, who finds that some TV is far from dumbed down

November 12, 2009

The Ricci tensor minus half the metric tensor times the contracted curvature tensor is proportional to the stress energy tensor." Who says TV is dumbing down? This is one of Einstein's equations for general relativity, which explains how gravity works. Professor Michio Kaku scribbled it on a blackboard in a deserted warehouse. He looked diminished in that empty space, a symbol for human insignificance in the face of the cosmos.

Michio, who seems to be everywhere on television at the moment, was demonstrating what happens when Einstein's equations are applied to the physics of a black hole. They break down. No matter how you juggle the terms, the solution is always infinity, an empty warehouse stretching out for ever.

Who's Afraid of a Big Black Hole? (Horizon, BBC Two, Tuesday 3 November, 9pm) was an investigation into one of the most astonishing phenomena in the cosmos. A point infinitely small and infinitely dense that has the power to peel stars and rip up space and time. At the moment, it's impossible to see a black hole. But we did get a close-up of the pupil of Professor Andrew Strominger's eye. It had a certain gravity as well as gravitas. Don't get too close to him; it could be dangerous.

The clever camerawork continued throughout. Each scientist was interviewed half in shadow as if at any moment they were about to be sucked into oblivion, and Professor Lawrence Krauss was split in two as he explained that a particle, in the quantum world, could be in many places at once. That would be a useful trick to learn. Then I could attend meetings and go to the cinema at the same time.

Professor Max Tegmark stood by a waterfall to explain how black holes worked. I caught the occasional word over the thunder of H2O. Boom! "Approach." Crash! "Traffic accident." Roar! "Possible to be alive." "Do you think he'll catch cold standing there?" asked the daughter, who is just beginning to realise that there is a world outside the pages of Heat magazine. "He's absolutely soaked."

That waterfall means I will never know what has always puzzled me about black holes, which is why they emit radiation when not even light is supposed to escape from them. Having dried himself, Max merely restated the problem instead of answering it. "As you approach the centre of a black hole, you reach the inner horizon where everything falling in meets matter being pushed out by the hole's rotation." It sounds like a faulty waste disposal unit.

Professor Ramesh Narayan said that not only is there a massive black hole at the centre of our galaxy but that there are millions of smaller ones dotted throughout the rest of it. He stopped short of saying that one of them was in banking. But he did say that the mass of the black hole is proportional to the mass of the galaxy and that it plays a part in determining its shape, size and evolution.

We are still a long way from understanding the most powerful vacuum cleaner in the Universe. To grasp the physics of a black hole, scientists must integrate the theory of relativity with that of quantum mechanics. That involves much head-scratching, with very little immediate impact on the economy or society. So perhaps they should focus on what people really want, like a self-assembling bow tie or something.

Also doing his best to show that TV need not dumb down was Diarmaid MacCulloch. The first programme of his six-part series A History of Christianity (BBC Four, Thursday 5 November, 9pm) showed just how much knowledge could be packed under one panama hat. I feared the consequences if he removed it. After the sack of Jerusalem in 70AD, Christians had to find a new centre for their faith. Should they go East or West? Diarmaid hit the Eastern trail, the brim of his hat flapping in the breeze.

There he met one Father Fady Abdulahad, who claimed that his church spoke a dialect of Aramaic, the language Jesus used. Eastern Christians, he said, are poets; those in the West are philosophers. But back in the 4th and 5th centuries the Eastern ones showed that they, too, could indulge in a spot of extended reasoning if they had to. Which they did, over the nature of Christ. Was he man and God or was he of one substance with the Father? Quantum mechanics would admit both possibilities.

Eastern Christianity reached as far as China. A man called Martin Palmer, who constantly threatened to upstage Diarmaid, had discovered a site on which a church once stood. But the locals shooed them away. Which, funnily enough, is what their ancestors did to Christians in the 9th century. Although they did it with swords. Can't wait for the second programme.

Gary Day is principal lecturer in English, De Montfort University.

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