Space-Time is Different for Various Elementary Particles: The State of the Early Universe

Space-time as we know it did not exist before the Big Bang, the origin of the Universe. So how did it form? Creating normal space-time from an earlier state dominated by quantum gravity has been studied for years; now, recent analyses reveal that not all elementary particles may be subject to the same space-time.

After the Big Bang occurred, the Universe was so dense and hot that elementary particles felt the existence of gravity strongly. For decades, physicists around the world have attempted to discover the laws of quantum gravity describing this phase of universe evolution. In this latest study, the researchers proposed their own model of the quantum universe, which possessed different elementary particles that "experienced" the existence of different space-times.

The model itself has an image of reality that's quantum, and so has characteristics extremely different from those of the world we deal with every day. Using the model, the researchers were able to ask a variety of questions concerning the state of particles and space-time.

Answering these questions wasn't easy. They first derived patterns of interaction between quantum gravity effects and matter for the two mathematically simplest cases: for zero rest mass particles and for simple non-zero rest mass particles. In the Standard Model, which in modern physics describes the elementary particles and their interactions, the relevant massless particles would be photons, and scalar non-zero rest mass particles with mass--the famous Higgs boson, responsible for the mass of the other particles.

After deriving the equations representing the behavior of particles in accordance with the quantum gravity model, the researchers checked whether similar equations could be obtained with the use of ordinary space-time with different symmetries.

"According to the simplified model we researched, regardless of whether the photon has great momentum or less, more energy or less, space-time appears to be the same in all directions," said Jerzy Lewandowski, one of the researchers, in a news release.

The same wasn't true for particles with mass, though. The existence of mass imposed specific additional conditions to the theory, which meant that they experienced different space-times than photons.

"Particles with mass not only experience different space-times than photons do, but each sees its own private version of space-time depending on the direction it moves in," said Andrea Dapor, one of the researchers, in a news release. "This finding really took us by surprise."

The findings were funded by grants from the Polish Ministry of Science and Higher Education and the Polish National Science Centre.