Formulas are usually developed using
theory and then tested using experiments
- but for high-energy particle collisions, it
was more practical to work the other way.
Image: iStockphoto

For more than eighty years, scientists have tried to uncover the mathematical laws governing the behaviour of colliding particles.

Particle accelerators like the Large Hadron Collider (LHC) were created to investigate collisions at massively high energy levels, but they do not reflect the everyday atomic collisions going on all around us. 

These collisions are what make lasers and fluorescent lights work, cause the ozone layer to exist and will be vital to fusion power.

Doctor Alisher Kadyrov, Professor Igor Bray and Professor Andris Stelbovics from Curtin University’s newly-established Institute for Theoretical Physics and their fellow researchers have, following ten years of investigation, found the most general formulae that govern these collisions.

With a proper understanding of the underlying mathematical rules, scientists can make accurate models of systems that would be impossible to physically build.

“Our goal as theorists is to be able to describe the experiment. Then, when our theory is accurate, we can apply it to cases where the experiment is just too expensive,” says Prof Bray, director of the Institute.

“For example, we might work with the Atomic Energy Agency who want a model of electron interactions with a bunch of atoms in a fusion reactor, which no experiment can do.”

In quantum mechanics it is impossible to predict exactly the outcome of any single collision; at this level, probability rules.

“You can never predict the outcome of any individual event, but if you have that event thousands of times, you can predict the probabilities of every outcome exactly. It’s totally counter-intuitive to everyday life,” says Prof Bray.

“There’s an important class of collisions that involve atomic breakup, and until now we haven’t had a formula for them.”

Using supercomputing facilities at iVEC and the ANU, Prof Bray and his partners ran repeated simulations of these collisions and worked out how to computationally model these collisions.

They have spent the ten years since working backwards to find the underlying formulae.

This is very unusual; ordinarily, scientists come up with an equation, plug in their figures and see if the results match the experiments.

The results of their breakthrough study have been published in Annals of Physics, and they now wait for physicists around the world to scrutinise their work.

The creation of a formal mathematical treatment of quantum mechanical collisions was a lifelong ambition for some physicists.

“Our advantage over those people has been that we’ve had access to supercomputers that have allowed us to find a solution computationally,” says Prof Bray.

“Then we could go back and say ‘why does it work’, and it’s a lot easier to solve a problem when you know you’ve already used a computer to get the right answer.”