Reminiscent of how humans used to think the earth was a myriad of shapes and sizes before discovering that it was actually a sphere about 12,742 km in diameter, we are now beginning to have revelations about our universe which may give it a distinct shape and size.
The idea that the universe is finite and relatively small, rather than infinitely large, first became popular in 2003, when cosmologists noticed unexpected patterns in the cosmic microwave background (CMB) – the relic radiation left behind by the Big Bang.The CMB is made up of hot and cold spots that represent ripples in the density of the infant Universe, like waves in the sea. An infinite Universe should contain waves of all sizes, but cosmologists were surprised to find that longer wavelengths were missing from measurements of the CMB made by NASA’s Wilkinson Microwave Anisotropy Probe.
One explanation for the missing waves was that the universe is finite. “You can think of the Universe as a musical instrument – it cannot sustain vibrations that have a wavelength that is bigger than the length of the instrument itself,” explains Frank Steiner, a physicist at Ulm University in Germany.