Hawking’s final theory of the Big Bang provides a bold and surprising answer. It envisages the Universe as a holographic projection.
Stephen liked to visualise this idea in a disk-like image of the kind shown above. The outer circle depicts a timeless hologram consisting of countless entangled qubits.
The disk shows the evolution of an expanding Universe that projects down from this. The origin of the Universe lies at the centre of the disk and it expands outward in the radial direction.
It is as if there is a code operating on the entangled qubits that brings about the Universe and this is what we perceive as the flow of time.
Crucially, by taking a fuzzier view of the hologram, one ventures farther back in time, toward the interior of the disk. It is like zooming out. Eventually, however, one runs out of bits. This is the origin of time, according to our theory.
There can be nothing before the Big Bang, because the past that holographically emerges doesn’t extend further back.link