Nine Lessons and Carols: The Third Lesson: Seeing Dark Matter


“The people that walked in darkness,” goes the third lesson, “have seen a great light.”

And there we have it. Two polar extremes: darkness and light.  An ancient metaphor born of a tiny spinning ball in a  vast universe.

One of the earliest concepts in our school science curriculum here in the UK is night and day, and how the whole globe gyrates in a kinky sun-dance which leaves some places in darkness for six months at a time, and others with white nights and seemingly endless daylight.

It is no wonder that night and dark are such powerful symbols, for there they are at our spiritual fulcrum. Look at Stonehenge, an ancient mechanism for harnessing the solstice sunlight; or the way iron age houses were so often built to allow in the light of the rising sun. Remember Candlemas, and the feast of the blessing of the candles, with the mediaeval beliefs that just the light of a candle could cure the plague.

These days, real darkness is hard to find. There are few places in Britain where you can get a truly black velvet night where stars and planets can be properly viewed. The interference of electric light is relentless.

And, where one can get a switch and flick it to produce instant light, we value it less. It is no longer thought a miraculous healer – though its place as a supplier of Vitamin A is now recognised.  But somehow, we take it for granted. It is commonplace. For now.

But whilst science has laid bare light, it has made dark yet more velvet and mysterious. Scientists are going to extraordinary, flamboyant lengths to create the ultimate darkness.

Around the middle of Italy there is a fabulous range of mountains named in English, Great Stone, and in Italian, Gran Sasso. It was where Mussolini was imprisoned in 1943 before a crack team of Nazi troops set him free, and on its peaks sits a station of the Rome Observatory.

But in its bowels is a place where scientists have sought and created darkness as thick as velvet. Thicker, and more profound. Its highest peak has a tunnel cutting through the mountain, And deep in that tunnel is a thick steel door. 1,400 metres of rock prevent any cosmic  rays reaching through to pierce the dark. In three cavernous halls there, scientists are conducting experiments

They’re looking at dark energy. And dark matter.

We know about roughly 4% of the stuff in the universe, because light bounces off it: so we can perceive it. But of the rest, about 73 per cent is a dark energy which acts to keep the universe in its shape, and stop it contracting in on itself.

And then there’s dark matter. Light doesn’t bounce off it, says Dr Chamkaur Ghag, a particle physicist from University College London, so we don’t perceive it.

There are more things in Heaven and Earth, as someone once said, than are dreamt of in our philosophy. And there are even more things than we dream of under mountains.

So these days the people who walk in a busy, frenetic light can, if they stop and but consider it, see a great and wonderful darkness. Darkness which reminds us that there is still, in this universe of ours, a vast and undiscovered country.


21 thoughts on “Nine Lessons and Carols: The Third Lesson: Seeing Dark Matter

  1. Long ago I remember someone saying “but you can’t see the dark if you switch on the light”. I love the dark – it is one of the joys here on Block Island – we can see the stars. This is a lovely series of posts – thank you

  2. lovely post Kate 😀 I once stayed at a farm bed and breakfast and it was so dark that when I got up at night (there was no moon that night) I was totally disoriented – couldn’t see a thing!

    1. I would love to be in a place that dark. We don’t have many truly dark places here – we have just Exmoor and Northumberland as Dark Sky Reserves, though Scotland has a number of them. I could imagine becoming a dark sky pilgrim. Especially as we are about to buy Felix his first astronomical telescope!

      1. Rural Wales usually has dark skies but over ten years in the Preseli Hills we’ve noticed increased light pollution.

        Still, when warned by local weather news we’ve spotted the ISS, and meteor showers are spectacular under cloudless skies, as is the Milky Way — mind-blowing to think it’s our galaxy viewed sideways on.

  3. Thank you. Thank you. Thank you, Kate. You have provided my #1 entry for my Gratitude List tonight:

    I do NOT live in darkness for 6 months of the year!!! 😎

  4. I think in reading this I am struck by how I take the contrast between light and dark without enough consideration. There is so much to what you’ve shared here, Kate. I really enjoyed reading it. I’m headed off to bed soon, and I will relish the dark.

    1. I hope you had a great night’s sleep in the cradle of the dark, Debra. As you say, there is a great deal to unpack with this contrast man has used in his stories for millennia.

  5. It’s a privilege to live here in Colorado where the mountains provide an escape from light pollution and a view of the spectacular night sky that few in the US enjoy.

    1. I am always amazed when you step into a black forest, how much light there really is. One can usually find one’s way, even at midnight. Course, my problem is that the dog disappears, all except for a triangular light patch on his rear. It needs considerable tracking skills to keep tabs on him in the dark.

  6. That is going to extreme lengths indeed to take a dim view of things!
    I recall that guides to cave systems would swich out all light to let people experience ‘absolute’ darkness. It created serious hysteria in some. Many have never been in ‘total’ darkness (as far as eyesight is concerned, I mean) in their lives. Even when one is blindfolded in a dark room, some light filters through.

      1. Of course, they seldom do it for long enough for the reality to sink in. It normally takes a few minutes for the eyes to adjust to what little light there is, and reveal that a place is not truly dark. When, after long enough, the blackness is still absolute – that is when some freak out,

      2. I think was already freaked out whe the French guide announced we were 2km underground — the lights on the electric train were off just long enough for the pre-phase of hysteria to kick in. The kids said nothing — they were either traumatised or bored.

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