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Firing lasers into a box made of gold – the race to turn light particles into matter

This could prove a neater way to investigate the fundamental building blocks of nature than examining the debris created by high-energy particle collisions.

Dynamite with a laser beam: artist Yvette Mattern's Global Rainbow in Whitley Bay, 2012. Photo: Getty
Dynamite with a laser beam: artist Yvette Mattern's Global Rainbow in Whitley Bay, 2012. Photo: Getty

By the time you read this, someone might already have done it. The publication of a report in May marked the beginning of the race to turn light into matter. Once the race is won, we could enter a new era in particle physics experiments but the real prize is far more valuable. This is about understanding the roots of our existence.

The idea of creating particles from light was dreamed up in 1934. The basic procedure is to smash together two photons, which are bundles of light energy. Calculations showed that, if done correctly, two particles of matter would magically appear in place of the light. The procedure invokes Albert Einstein’s equation E=mc2. The same equation lies behind the release of energy from nuclear fission. Not only do we now have atomic bombs but, it turns out, we also have the technology to take things in the opposite direction.

A team of physicists from Imperial College London has worked out the details. To collide photons to make matter, first fire a laser into an empty box made of gold. This creates a sea of photons with enormous amounts of energy. At the same time, accelerate a beam of electrons to nearly the speed of light using another high-power laser. Slam those electrons into a slab of gold and they will release a stream of photons to collide with the sea of photons in the gold box. The result will be the creation of electrons – one of the building blocks of matter – and positrons, the electron’s antimatter particle.

Now that it’s clear how to do it, there is little stopping scientists from performing this astonishing trick tomorrow. There are many facilities around the world that could string the various necessary technologies together.

What’s more, ramp up the energies of the lasers and it should eventually be possible to create bigger, heavier particles out of light. This could prove a neater way to investigate the fundamental building blocks of nature than examining the debris created by high-energy particle collisions in machines such as Cern’s Large Hadron Collider. Yet the big spin-off of such feats is in firing the imagination. This is science for the soul.

What this branch of physics teaches us is that our everyday intuition is not to be trusted. That matter and energy are two forms of the same stuff is entirely counter-intuitive. We have long given intellectual assent to the idea but it is so far removed from our day-to-day experience of the world that it may always seem implausible.

This interplay of light and matter is the rock on which the modern world is built. The silicon microchips in your smartphone and your laptop – maybe even your toaster – rely on the fluidity of matter. The microscopic electrical switches they contain work only because electrons are both matter and energy, flowing from one existence to the other as circumstances dictate.

Equally, we are solidly matter in our experience, yet we now know that we are made of stuff that can, in the right circumstances, be transformed into flashes of energy. That energy could, given sufficiently advanced technology, be turned back into us.

In some ways, it is a lesson about our impermanence but it is also a glimpse of our extraordinary gifts. We are matter that began its existence 14 billion years ago as a flash of primordial light. And now, that matter has learned the first step in repeating the process of its creation. For all the conflicts, disasters and alarming election results that human beings generate, we should still be proud of our species.