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There is no question more puzzling than this! The vast majority of scientists believe in the Big Bang, or Big Bang, theory – but what came before it? Everything indicates that it is impossible to know for sure!
The Big Bang itself, by the way, is already quite mysterious. According to the theory, about 15 billion years ago, all the matter that makes up the Universe was concentrated in a single point, which exploded, giving rise to everything we know… and even what we still don’t know. This bombastic origin is proven by several scientific observations, but it has some problems. The main one is that, by the laws of physics, the explosion would be subject to small fluctuations that would make the universe irregular – which does not happen in reality. “There are more than 50 theories that try to resolve this issue”, says physicist Augusto Damineli, from the University of São Paulo (USP). The most accepted idea was proposed by the American physicist Alan Guth in 1981: in the first fractions of a second, the explosion would have expanded at a speed much greater than that of light. That would have flattened out the Universe we observe, but covered up everything that happened.
If physicists have difficulty understanding what happened right after the Big Bang, finding out what happened before it is, therefore, a much more arduous task – even more so because it is likely that this phenomenon was not the beginning of everything. “The Universe already existed at the time of the Big Bang”, says physicist Mario Novello, from the Brazilian Center for Physics Research (CBPF), in Rio de Janeiro. Among the dozens of proposed models, it is possible that space and time have existed forever, that the Big Bang is the result of the collapse between different dimensions and that the explosion gave rise not to one, but to several universes.