Sadly, Professor Brian Cox’s TV series, Wonders of the Universe, has now come to an end, but not before our brain cells (or mine, at least!) have been stretched in four dimensions.
In the third episode, ‘Falling‘, Professor Cox describes how scientists have struggled to explain the effects of gravity – which is not, in fact, a physical force. “Gravity,” he tells us, “is the effect that the stars, planets and galaxies have on the very space that surrounds them.”
After Sir Isaac Newton’s initial attempts in the 17th century, Einstein finally got to grips with gravity in 1915. His Theory of General Relativity “explains to this day everything we can see out there in the universe that has anything to do with gravity and… it explains how gravity actually works.
“Space is not just an empty stage – it’s a fabric called space-time. This fabric can be warped, bent and curved by the enormous mass of the stars, planets and galaxies.”
Interesting, I think I’ve got that.
But then comes this fascinating concept: “Everything moves in straight lines over the curved landscape of space-time. So what we see as a planet’s orbit is simply the planet falling into the curved space-time created by the huge mass of a star.”
I love that idea, partly because it makes me dizzy.
Having dropped this delicate bombshell into the small and sparsely populated physics area of my brain, Professor Cox moved on to tackle black holes, “the most extreme examples of warped space-time.” Lurking at the centre of many galaxies, including our own, a black hole curves space-time more than any other object in the universe.
Astonishingly, black holes can be “smaller than an atom or a billion times more massive than our sun.” I can cope with the second idea but not the first. Smaller than an atom? How? I find that worrying, especially because I think there might be one on my desk.
Standing on the very brink of Iguazu Falls, with some mesmerising aerial photography of the river plunging headlong into an apparent void, Professor Cox likens the ever-increasing speed of water flow to the unimaginably powerful pull of a black hole.
At the very centre of a black hole, past the event horizon where even light cannot escape, space and time become infinitely curved and the centre of the hole becomes infinitely dense. Scientists call this a singularity – I like the word, because it also means something remarkable, out of the ordinary. And infinitely curved? That makes me think of the spirals seen in so many examples of prehistoric art, from Newgrange in Ireland to sites across the UK and continental Europe. I think ancient civilisations knew a lot that’s now been forgotten.
Anyway, with the singularity our present understanding of space-time comes to an end. Will we ever know more? Or will we be swallowed by a black hole just as the realisation dawns – and then have to start all over again?
In his fourth and final episode, Professor Cox deals with light, taking digital images of the Andromeda galaxy to illustrate how light can be seen as a messenger from the past, because it takes millions of years to reach our eyes. In fact, the light from some of the most distant galaxies started out on its journey before our solar system was formed. I was aware of this already, but it always boggles my mind.
He concludes with some interesting – some will probably say daring – theories about how our eyes have evolved and why.
Whatever your own opinions about the origins of life, you can’t deny that this series, with its awesome photography and ground-breaking approach, is an inspiration. Personally I’ve found it riveting to watch – a potentially daunting subject presented with clarity and enthusiasm. And I so want to visit some of the locations where it was filmed!