Every cosmologist and astronomer agrees: our Universe is 13.7 billion years old. Using cutting-edge technology, scientists are now able to take a snapshot of the Universe a mere heartbeat after its birth.
Armed with hypersensitive satellites, astronomers look back in time to the very moment of creation, when all the matter in the Universe exploded into existence. It is here that we uncover an unsolved mystery as old as time itself - if the Universe was born, where did it come from? Meet the leading scientists who have now discovered what they believe to be the origin of our Universe, and a window into the time before time.
The big bang theory holds that the entire universe was once packed tightly into an unimaginably dense and tiny space, known as a "singularity." That is, until roughly 13.7 billion years ago, when a colossal burst of energy and pressure started to give rise to entire worlds, galaxies and interstellar particles, forming the universe as we know it today.
But what brought about that big bang? Physicists are left scratching their heads at that question. Since the universe began on such a tiny level, the laws of relativity don't fully apply. Instead, quantum theory, which deals with the lawless and bizarre world of the very small, must also be summoned.
Successfully answering the question of what existed before the big bang would require bridging the gap between the so-far mutually incompatible worlds of relativism and quantum mechanics. But even though that bridge has yet to be constructed, theories abound.
"Our universe could have either popped into existence or collided with another universe," theoretical physicist Michio Kaku told scienceline.org. "Big Bangs happen all the time."