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Are we in the middle of the universe?
Around 1927 Edwin Hubble discovered something incredible. Galaxies hundreds and thousands of light-years away were slightly redder than expected. This might seem unremarkable but light arriving from those distant galaxies should have been a very particular colour. The fact they looked redder than this implied something was happening to the light as it reached the Earth.
Over the vast expanse of space, between the atoms of Hydrogen and the atoms at the back of the astronomer’s eyes, the light had been shifted to a longer wavelength, being pushed further from the violet and closer to the red end of the rainbow. This is redshift.
For this to occur, the galaxies must have been moving away from us, causing the light to shift to a longer wavelength. Galaxies were moving away from the Earth, in all directions. In fact, as you looked further from the Earth, they were moving away proportionately faster. This phenomenon came to be known as Hubble’s law.
There are two profound conclusions from the observation of the recession of galaxies around the Earth. The first is that, if all of them are moving away from us, they were once much closer together. So close together, in fact, that they once formed a single point — a singularity — from which everything appeared. This point must have undergone a huge expansion, causing all the stuff within…
