In the beginning was the Bang? Universe may not have an end, but it definitely had a beginning, claim physicists
The Big Bang theory was coined in the 40s – but physicists still puzzle over whether it even happened.
Frederick Hoyle, the astronomer and physicist who coined the term, ‘Big Bang,’ much preferred the idea that the universe might have existed forever.
Now two mathematicians claim to have ‘proved’ that it didn’t – it might not have an end, but the universe definitely had a beginning.
Big Bang? Two mathematicians argue that although the universe may NOT have an end, it definitely did have a beginning – and they have the maths to prove it
The universe IS expanding – so it can’t simply have ‘sat still’ forever. But some mathematicians thought it perhaps worked on a ‘cycle’
The future might be eternal, but the past is not, claim the mathematicians from Tufts University.
‘One of the most basic questions in cosmology is whether the universe had a beginning or has simply existed forever,’ say mathematicians Audrey Mithani, Alexander Vilenkin. ‘It was addressed in the singularity theorems of Penrose and Hawking, with the conclusion that the initial singularity is not avoidable.’
The universe IS expanding, which fits with the theory of an ‘initial singularity’ – an infinitely dense object that exploded into the Big Bang.
This is measurable from Earth – and so the universe can’t simply have ‘sat still’ since the beginning of time.
However, three theories allow the universe to expand without requiring a ‘beginning’.
‘There are, however, three popular scenarios which circumvent these theorems: eternal inflation, a cyclic universe, and an ‘emergent’ universe which exists for eternity as a static seed before expanding,’ say Mithani and Vilenkin.
The pair mathemtacially analysed the three scenarios and found that eternity cannot exist in our expanding universe. There WAS a beginning, whether or not it was the Big Bang.
‘We have addressed three scenarios which seemed to o er a way to avoid a beginning,and have found that none of them can actually be eternal in the past,’ say Mithani and Vilenkin.
Put simply, the future could be eternal, but the past cannot.
Albert Einstein: He was right about the expansion of the universe
Of the three ‘theories’ of an eternal universe, the mathematicians say, ‘Two of these scenarios are geodesically incomplete to the past, and thus cannot describe a universe without a beginning. The third, although it is stable with respect to classical perturbations, can collapse quantum mechanically, and therefore cannot have an eternal past.’
‘Mithani and Vilenkin point to a proof dating from 2003 that these kind of past trajectories cannot be infinite if they are part of a universe that expands in a specific way. They go on to show that cyclical universes and universes of eternal inflation both expand in this way. So they cannot be eternal in the past and must therefore have had a beginning,’ says MIT’s Technological Review, which reported the research.
The expansion of our universe seems to bear the signs of a Big Bang-type event, in the form of ‘waves’ seen in galaxies.
Galaxies and clusters of galaxies are clumped together into walls and filaments, with giant voids between. These structures grew out of subtle variations in density in the early universe, which bore the imprint of “baryon acoustic oscillations” — pressure-driven acoustic (sound) waves that passed through the early universe.
Billions of years later, the record of these sound waves can still be read in our universe.
‘Because of the regularity of the ancient sound waves, there’s a slightly increased probability that any two galaxies today will be separated by about 500 million light-years, rather than 400 million or 600 million,’ said Eisenstein.
In a graph of the number of galaxy pairs by separation distance, that magic number of 500 million light-years shows up as a peak, so astronomers often speak of the ‘peak separation’. The position of this peak depends on the amount of dark energy in the universe. But measuring the distance between galaxies depends critically on having the right distances to the galaxies in the first place.