It could hardly be more complicated: tiny particles whir around wildly with extremely high energy, countless interactions occur in the tangled mess of quantum particles, and this results in a state of matter known as "quark-gluon plasma". Immediately after the Big Bang, the entire universe was in this state; today it is produced by high-energy atomic nucleus collisions, for example at CERN.

Such processes can only be studied using high-performance computers and highly complex computer simulations whose results are difficult to evaluate. Therefore, using artificial intelligence or machine learning for this purpose seems like an obvious idea. Ordinary machine-learning algorithms, however, are not suitable for this task. The mathematical properties of particle physics require a very special structure of neural networks. At TU Wien (Vienna), it has now been shown how neural networks can be successfully used for these challenging tasks in particle physics.

Neural networks

"Simulating a quark-gluon plasma as realistically as possible requires an extremely large amount of computing time," says Dr. Andreas Ipp from the Institute for Theoretical Physics at TU Wien. "Even the largest supercomputers in the world are overwhelmed by this." It would therefore be desirable not to calculate every detail precisely, but to recognize and predict certain properties of the plasma with the help of artificial intelligence.

Therefore, neural networks are used, similar to those used for image recognition: Artificial "neurons" are linked together on the computer in a similar way to neurons in the brain—and this creates a network that can recognize, for example, whether or not a cat is visible in a certain picture.

When applying this technique to the quark-gluon plasma, however, there is a serious problem: the quantum fields used to mathematically describe the particles and the forces between them can be represented in various different ways. "This is referred to as gauge symmetries," says Ipp. "The basic principle behind this is something we are familiar with: if I calibrate a measuring device differently, for example if I use the Kelvin scale instead of the Celsius scale for my thermometer, I get completely different numbers, even though I am describing the same physical state. It's similar with quantum theories—except that there the permitted changes are mathematically much more complicated." Mathematical objects that look completely different at first glance may in fact describe the same physical state.

https://phys.org/news/2022-01-big-artificial-intelligence.html