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Probing Deeper

In this section we'll bring you in more detail some of the ideas that the Festival is helping to develop on its travels around the communities of the Highlands.

Here is a summary of the talk by Howie Firth on The Physics of the Wood of Hallaig, given at Sabhal Mòr Ostaig in Skye last year. It looks at the great Gaelic poem by Sorley MacLean and follows up the extraordinary image at its heart an image of Time.

‘Tha tìm, am fiadh, an coille Hallaig’

Tha bùird is tàirnean air an uinneig
trom faca mi an Àird an Iar
’s tha mo ghaol aig Allt Hallaig
’na craoibh bheithe, ’s bha i riamh

eadar an t-Inbhir ’s Poll a’ Bhainne,
thall ’s a bhos mu Bhaile Chùirn:
tha i ’na beithe, ’na calltainn,
’na caorann dhìrich sheang ùir.

‘Time, the deer is in the Wood of Hallaig.’

The window is nailed and boarded
Through which I saw the West
And my love is at the Burn of Hallaig
A birch tree, and she has always been

Between Inver and Milk Hollow,
Here and there about Baile-churn:
She is a birch, a hazel,
A straight slended young rowan.

This is a remarkable poem – that goes without saying. But the power of its central image is so deep that it covers territory where we might not expect to find the power of poetry acting so strongly. The image of Time takes us into the territory of physics – and gives us insight into areas on the very frontier.

A great deal in physics stems from our choice of an image of Time. The ancient Greeks had two alternatives. One was as a turning millstone – slowly and inexorably making its round like the starry sphere of the sky. That image turns up in some unusual places, for instance in the story of the king who had a magic mill that could grind out whatever he desired, a mill which ended up at the bottom of the Pentland Firth. It could grind out gold or salt – two substances connected with Time, gold being impervious to Time and salt making everything it touches immune to decay.

That image of time is cyclic and rather rigid, but a freer alternative is of time as a river. Here we have something linear, but also dynamic – and a bit more unpredictable, with the swirl and flux of the flowing water.

Now both these images are rather ‘unalive’. The turning millstone is manmade and predictable, the river natural but still inorganic. Can we get something more alive?

The answer is yes, in various mythologies around the world. We find Time as a reed, in some cultures, and you can see why, with the plant’s linear growth.

And we find Time as a snake in others, and again you can see how, with the snake swallowing its prey which is slowly transformed by the digestive system that it is gradually passed through.

So now let us look in more detail at Sorley MacLean’s poem – and we can see images of Time as something alive – and not only one image, but two. There is the time of the deer flitting through the Wood of Hallaig – and the time of the Wood itself.

We can see the two processes of life, operating in different direction. Vertically there is the slow – ever-so-slow – growth of the trees, the birch and the hazel and the rowan; and the growth of the trees – which are compared to the growth of humans:

tha i ’na beithe, ’na calltainn,
’na caorann dhìrich sheang ùir.

She is a birch, a hazel,
A straight slended young rowan.

And then on a horizontal axis there is a different type of time – the time of the deer, a much faster and more elusive time, slipping past amongst them.

‘Tha tìm, am fiadh, an coille Hallaig’
‘Time, the deer is in the Wood of Hallaig.’

Now physics today has a problem, which increasingly is being recognised as to do with the nature of Time – or the way in which picture Time. The two great pillars of modern physics, quantum theory and relativity, are incompatible when it comes to picturing Time, and for more than eighty years physicists have wrestled unsuccessfully with the problem.

Relativity operates within an existing framework of time. Time and space together form the platform on which matter moves. But quantum theory seems to require time to be somehow more fluid and spontaneous, to emerge along with matter out of the deep. Immense efforts have been made to fit the two theories together, with outcomes that have opened up new vistas – for instance of the first moments of the universe; but the fit is not yet seamless. And it looks as if the fundamental incompatibility may only be completely resolved when we develop a more comprehensive picture of time out of which the time of relativity and the time of quantum theory can each emerge in their own particular situations.

Now one promising theory has been for two-way time – to suggest that at the quantum level there may be two opposing flows of time that interact like two currents of the sea, and where the current meet and the waves break we may find the world of matter surfacing out of the underlying flux.

That’s something that we can speak of in more detail on another occasion. For there is a second picture that is even more appropriate to the two-dimensional image of Hallaig – and that is two-dimensional time.

Sir Arthur Eddington, the man whose observations of the planet Mercury confirmed Einstein’s theory of general relativity, tried out some different mathematical forms of relativity. In one of these he made a modification to the familiar picture of three dimensions of space and one of time, to give instead two space dimensions and two time ones. He said that a world of two-dimensional time would ‘defy imagination’; but he continued to investigate the format, and moved on to a version in which three-dimensional particles could exist in a two-dimensional time.

That was eventually forgotten; but in 2007 Itzhak Bars of the University of Southern California in Los Angeles came up with a situation which two-dimensional time could solve.

He noted that in quantum theory there seems to be a deep link between position and momentum – in fact the two are linked in the uncertainty relationship which tells us that the more precisely we know the one, the less sure we can be about the other.

So he thought that we need a mathematics in which the two are on a completely equal footing. He looked for this, and found that the only way he could get there was to add in two extra dimensions, one of time and one of space. In a six-dimensional universe, with four dimensions of space and two of time, he could get the deep underlying symmetry between position and momentum that he needed.

And strangely enough, this six-dimensional universe with its two dimensions of time was not so much beyond experience as we might have feared. The various rules of symmetry kept it quite close to ‘normal’. The two dimensions of time did not lead to time travel or any bizarre paradoxes.

He did come up with quite a beautiful image of the six-dimensional world and its relation to us. The situation is rather like what happens when we hold our hand up by a lamp and see a two-dimensional shadow on the wall. Bars says that the six-dimensional world is the underlying one, and that it throws up a variety of forms of four-dimensional ‘shadows’ – of which our universe is one.

So here is a strange new world to explore – first of all mathematically, and then by experiment, if suitable predictions can be made that we can try to test. And we have an image from the world of poetry to help us think about the new possibilities – a picture of time in two different dimensions, the time of the Wood of Hallaig and the time of the deer flitting through it.

‘Tha tìm, am fiadh, an coille Hallaig’

‘Time, the deer is in the Wood of Hallaig.’






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