Short pieces prepared for journals, exhibitions and talks.

Sunday
Apr122015

Brightness

An illustrated talk prepared for the TEDx Marrakesh conference in February 2015.


Hello everyone.  My name is Geraldine Cox. It is a great pleasure to be here. I am an artist working at the Physics department of Imperial College in London, where I have a project called ‘Finding Patterns’. Finding Patterns aims to share some of the beautiful things about Nature that are often hidden from view of everyday life. I use all sorts of ways to express these ideas – paintings, prose, film or even inventing and building new things like a sunshine powered cinema.

Today, inspired by the theme of brightness, I’d like to open our minds to the world of light, share how Nature chooses to be bright and explore what we might learn for life.

 

- 1 -

The world of light is far greater than the eye perceives. Here in this darkened space, you might think it to be relatively empty of light; the contrary is true, the room is full of light.

There is obviously the light of the projector bulb and the muted overhead lights. We can see it scattering from the projector screen, from the dust motes above us and coming off some of the atoms and molecules that make the room in the ‘colour’ hues of the walls and the curtains.

If I turned on a radio, we would hear voices from around the world. Radio waves too are light.  The difference between radio waves and the visible ones you see are the lengths of the waves.  Radio waves can be the size of buildings, from sheds to tower blocks, from a metre to several hundred long whereas visible light is very small, a thousandth of a hairs breadth. Because our eyes do not detect these long wavelengths of radio light we use the electronic circuitry of a radio. Using our imagination for a moment, we can see radio waves zooming across this space in all directions, coming from transmitters across the globe and in space, bringing us news and information. 

In this room, there is also light from the early universe.

Source: Planck, ESA

This light is 14 thousand million years old, and we are all touching it, always, When the Universe was very young, it was much smaller and simpler, a hot dense soup of charged matter and light. Light was scattered ceaselessly by matter, like in a cloud or in the foam at the seas edge. As space expanded and became less dense, a point was reached early on when light was set free to travel.  This light has been travelling ever since and reaches us now as light waves we call microwaves that are typically around 1mm long. This is the oldest and most predominant light in the Universe, making up 95% of all light energy.  You have detected it; it is around ½% of the crackle on your radio.  When we look carefully at this microwave light using special detectors it reveals to us the early structures of the Universe. Those structures were the beginnings of the galaxies we see today.

What other light is in this dim room?

There is the radiated heat of our bodies.  This is another type of light, infra-red light, the waves are around the size of a needlepoint and we sense them on our skin.

 

With different eyes we would have different powers and perspectives as we see the internal structures of things; the friction of a fountain as it falls upon water, and the glow of life.

We can continue travelling along the light spectrum to the visible light we have discussed. Beyond this there are even shorter waves of ultra violet, X and gamma rays, which play  a more minor role in the room as they tend mostly to be produced in our Sun and in space and most are absorbed in various ways before reaching this room.

So we can visualise this dim space to be dancing with light waves: all these waves travelling in all directions and of wildly varying sizes. A piece of light travelling from the lamp over here, vast radio waves washing in from the continents, the ancient glow of the early universe and the radiant heat from our bodies. We are in a room that is quite bright with light though only a miniscule part - the visible light we detect with our eyes is made apparent to us. Brightness takes imagination and creativity to find.

 

- 2 -

It's natural to ask, how is all this light created? Light has its origins in the changing motion of electrically charged matter.  Everything, all atoms, are made up of positive and negative pieces of charged matter. You may have experienced this charge as a child if you ever rubbed a balloon and watched your hair stand on end, or put your tongue across a small battery and felt the tingle. Light is made when charges accelerate. Light and the movement of charge go hand-in-hand: light makes charges move, and moving charges make light.

Much of the colour we see in the world, the hue of our skin, the rosy peel of an apple and the vibrant colours of a painting is made by the motion of electric charge inside atoms and molecules.  

Matisse said ‘a painting must possess a real power to generate light and that he was conscious of expressing himself in light’. He was right, when he chose his gorgeous pigments, he was selecting atoms and molecules that would choose coloured light for him. This process is lovely to think about and can be discovered by entering the atom.  When we enter, we find that we can think of atoms like tiny musical instruments, and that each element has its characteristic notes which we can show as a series of concentric rings.

Here is a hydrogen atom, the simplest most abundant element in the Universe and here are all the notes, shown accurately just as we measure them to be.  Starting with the outer ring, there is this low frequency base note and we go up to the top and have a descant sound. We’ve translated the first 11 notes into sound.

But in reality, the notes are not sound, they are light. So, hydrogen will emit these very particular notes of light, these and only these. 

Remarkably, anytime we look into space and see light with these colour notes we know it is light that has come from hydrogen.

We can explore all atoms and molecules like this and each will have its own particular song.  Here are the notes of oxygen.

With the bass notes going on up into the centre towards the descant frequencies.  And here is its song; the light notes oxygen absorbs and emits are these.

Nature’s musicality is revealed in this picture of the visible light spectrum of the Sun.  The absent notes are the decisive selections made by atoms and molecules on Sunlight’s journey to earth.  Each atom or molecule extracts particular pieces of light corresponding to its song and drinks up the energy.

Back on Earth, The greenness of leaves and stems is owed to chlorophyll molecules choosing red and blue light to power the plant, for the process of photosynthesis, leaving a vivid world of green.  

 

- 3 -

This important selection process where atoms and molecules wholly absorb or brightly release particular light waves or notes is one of resonance. Most waves do nothing to the atom – the length of the wave is too long or too short to be of any interest – but when the wave is exactly right the atom dances excitedly, soaring to an extraordinary peak.

Everyone knows what this is in life: when you see an old friend, read a poem where the form brilliantly echoes the idea or have the perfect day.  We are energised, filled with a great sense of delight, enrichment and wellbeing. We can go through life. Nothing much happens when we are here or here, but when resonance happens, there is this fantastic transfer of energy and things start to dance.  Even small amounts of these well-chosen energies can create magnificent results.

Resonance pops up again and again in Nature and is essential to music where the geometry of the instrument, the size and shape of the pipe, the length of the strings defines the resonant notes. A vivid musical illustration of resonance can be seen by scattering dust over a flat plate and vibrating the plate at different frequencies.  When just the right note is struck, beautiful patterns form.

Photo credit: Stephen Morris

In 1809, Napoleon and his court were fans of these demonstrations and hosted their discoverer, Ernst Chladni, and his sound figures.  Around 100 years later in the early 20th century, with the advent of quantum mechanics, we discovered similar formations in the atom.

Here are a few of the possible formations of a hydrogen atom. The form of the atom depends on which note it plays.  Napoleon could never have imagined that the patterns he found so mesmerising on the dusty plate might also occur at the heart of the atom to colour our world.

Resonance happens when you find the notes that something naturally sings: The exhilarating notes at which energy flows easily in and easily out. Nature cannot resist a resonant note.  These two connected pendulums will talk if they are of the same length and so share the same frequency.  They will not dance like this for any other beat.

Nature’s urge to dance brilliantly to particular beats is a vital element of our world of motion, colour and music and leads me to close by asking, is there something we can learn for living? 

From an artists’ point of view and for all of us who want to communicate, I think this resonant point is the one we seek: the strong connection between the image and idea, the poem and the impulse, the music and the feeling, the dancer and the beat. 

Resonant works are the ones that dance while the others sleep.  

And for all of us in life - we each of us have our own individual set of natural notes. So, I wonder too, if an important aspect of the art of life might be to courageously search for our unique resonances, carefully and imaginatively seeking the things that drive and excite us, so that we in turn are bright.