Deep Time


Reading Neil MacGregor’s A History of the World in 100 objects, on chapter 91 I came across the concept of ‘deep time’. And deeply troubling it must have been in the 1800s; as people began to come to terms with it.

‘Deep time’, I discover, was the dawning recognition that the world was much much older than people had thought – and far less constant. Prior to ‘deep time’ the world was assumed to be capricious (hence gods) but unchanging (hence the need to pacify them).

The geneticist Steve Jones (who I’ve been fortunate to spend some time with) is quoted thus: 

The biggest transformation since the Enlightenment has been a shift in our attitude to time, the feeling time is effectively infinite, both the time that’s gone and the time that’s to come. It’s worth remembering that the summit of Everest, not long ago in the context of deep time, was at the bottom of the ocean; and some of the best fossils of whales are actually found high in the Himalayas. 

Deep time threw everything up in the air – origins, purpose and our place not just in the world; but in those unfathomably vast aeons of time and the unimaginably vast expanse of the universe. We went from the centre of everything to tiny, transient and trivial.

Faced with this reality I’ve often cheered myself up with the thought that bits of me were formed in stars. And I read somewhere once, we all have some molecules in us which were once in Julius Caesar and Napoleon. 

Nice therefore to read an entire feature in the New Scientist today, predicated on exactly this; the calcium atom formed in a star which is now in our bodies, the water in our blood which was once in a dinosaur etc. But the one which sparked my imagination was Stephen Battersby’s story of the iron ion formed in a supernova. 

I pick up the iron nucleus’s journey here, as it is spat out from the periphery of a large black hole: 

By the time our iron nucleus leaves this maelstrom, it has an energy of about 8 joules, millions of times greater than anything Earth’s Large Hadron Collider can provide. Now at about 99.9999999999999999 per cent of the speed of light. It is flung out of its native galaxy into the emptiness of intergalactic space.

As the iron nucleus wanders between galaxies, pulled this way and that by magnetic fields, its view of the universe is a strange one. At this ludicrous speed, the effects of relativity compress faint starlight from all directions into a single point dead ahead. Relativity also does strange things to time. While the nucleus is travelling, the universe around it ages by 200 million years. In another distant galaxy, Earth’s sun completes one lazy orbit of the Milky Way, dinosaurs proliferate, continents split and rejoin. But to the speeding nucleus, the whole trip takes about 10 weeks.

On the last day of its intergalactic holiday, our traveller finally approaches the Milky Way’s messy spiral. It heads towards a type G2 dwarf star, and a planet where the dinosaurs are now long dead. According to onboard time, the iron nucleus passes Pluto just 16 microseconds before it reaches Earth. When it arrives here we call it an ultra-high-energy cosmic ray.

The wispy gases of our upper atmosphere present a barrier far more challenging than anything it has encountered so far. The iron nucleus hits a nucleus of nitrogen, and the extreme energy of the collision not only obliterates both, but creates a blast of pions and muons and other subatomic particles, each with enough energy to do the same again to another nucleus, generating a shower of ionising radiation that cascades down through the atmosphere. 

Some of these particle will hit an airliner, slightly increasing the radiation dose of passengers and crew. Some may help trigger the formation of water droplets in a cloud – perhaps even help spark a lightning bolt. Some will find their way into living cells, and one will tweak an animal’s genes, spurring on the slow march of evolution. But it is very likely that nobody will even notice as the atmosphere scatters the ashes of an exceptional traveller that once flirted with a black hole in the faraway Virgo Cluster.

Remarkable. When I had the chance in 2011 to spend a couple of hours with Sergei Krikalev (at that time the cosmonaut who had spent the most time in space) he told me you typically see eight to ten scintillations in your eyes every minute in orbit – little flashes in your vision – which are the cosmic rays punching through your eyeballs.

But this story of an iron nucleus would surely seem as far fetched to a person in 1815, as the things they believed then may sound to us now. A reminder that deep time for us, is only 200 years old – just a blink (or twinkle) of the eye for a cosmic ray.


20110714-090550.jpgToday I spent an hour, at the unveiling of a statue to Yuri Gagarin, with the man who has spent more time in space than any other – the Cosmonaut Sergei Krikalev.

Poised, distinguished and himself chipped from granite, he is definitely the man you would want in the space capsule with you if something went wrong. He’s ten years older than me and found himself circling the earth when the USSR imploded leaving him temporarily stranded in outer space. Having met him, I expect he took it in his stride.

I talked to him about fitness loss in space, cosmic rays causing flashes in your eyes (a dozen per half hour or thereabouts in his experience) and experiments to test what snails had in common with dinosaurs (inconclusive).

As you might expect, given the things he’s seen, he had some reasonably profound things to say about international collaboration, friendship and what humanity has and can achieve.

My summary of his wise words:

While the ancients thought the world was infinite – and perhaps bourne on the back of elephants – when you see it from orbit you see it is big, but really not that big – and above all you see it is finite.

That the international friendships he has made are his greatest treasure and that international collaboration in science and space has always transcended the politics in his time in space.

Space is unbelievably hostile. And when all that separates you from it is a few millilitres of aluminium – which you could easily puncture with a kitchen knife – you recognise how fragile your existence is.

To say that ‘going into space has been done’ and ‘there’s nothing more to do’, is like saying the Romans built roads so why bother building a train.

Finally – and his eyes lit up on this one – the future is always exciting, we will go further and we will always reach for the stars.

A ramrod straight, decent and good man I concluded, with the quiet bravery of a modern day Achilles.