If a new theory turns out to be true, the universe may not have started with a bang.

In the new formulation, the universe was never a singularity, or an infinitely small and infinitely dense point of matter. In fact, the universe may have no beginning at all.

"Our theory suggests that the age of the universe could be infinite," said study co-author Saurya Das, a theoretical physicist at the University of Lethbridge in Alberta, Canada.

The new concept could also explain what dark matter — the mysterious, invisible substance that makes up most of the matter in the universe — is actually made of, Das added. 

Big Bang under fire

According to the Big Bang theory, the universe was born about 13.8 billion years ago. All the matter that exists today was once squished into an infinitely dense, infinitely tiny, ultra-hot point called a singularity. This tiny fireball then exploded and gave rise to the early universe.

The singularity comes out of the math of Einstein's theory of general relativity, which describes how mass warps space-time, and another equation (called Raychaudhuri's equation) that predicts whether the trajectory of something will converge or diverge over time. Going backward in time, according to these equations, all matter in the universe was once in a single point — the Big Bang singularity.

But that's not quite true. In Einstein's formulation, the laws of physics actually break before the singularity is reached. But scientists extrapolate backward as if the physics equations still hold, said Robert Brandenberger, a theoretical cosmologist at McGill University in Montreal, who was not involved in the study.

"So when we say that the universe begins with a big bang, we really have no right to say that," Brandenberger told Live Science.