Back to the beginning of time
A Kiwi is figuring out what happened after the Big Bang, Paul Gorman reports.
Big Bang researchers at the University of Otago are making breakthroughs with new mathematical models that zoom in on the beginning of time.
Common belief is that the universe began expanding rapidly about 10 to the power of minus 36 seconds (0.00000000000000000000 0000000000000001 seconds) after the Big Bang.
Now, with the aid of maths, Dr Florian Beyer, of the Department of Mathematics and Statistics, and colleague Professor Philippe LeFloch, from the Universite Pierre et Marie Curie in Paris, are delving into even earlier moments in the life of our universe.
Their calculations describe the universe’s dynamics in an interval of time that is infinitesimal – between the start of time at 0 seconds, or as close to that as it is possible to get, and 10 to the power of minus 36 seconds.
‘‘Everything was started here and we would like to understand it,’’ Beyer said.
‘‘I expect to find more things – the sharper our models are and the more we focus in, the more we will see.’’
The Big Bang is believed to have occurred about 13.7 billion years ago, at which time the entire contents of the universe – all of space and time – were contained within an unimaginably dense and hot region. The subsequent extreme explosion and expansion is the commonly accepted explanation of the evolution of the universe.
Confirmation last year of the existence of gravitational waves is a potential game-changer for the two scientists, allowing them to sharpen their models even more and make predictions.
‘‘If in the future we become able to measure experimentally the imprints of the early universe dynamics using the new gravitational wave detectors, we would be closer to an answer to the question of how our universe was created,’’ Beyer said.
Gravitational waves are miniscule distortions of space-time caused by gargantuan cosmic events.
Albert Einstein predicted the waves in 1916, based on his general theory of relativity of the previous year, but doubted they would ever be detectable because they are so small. It wasn’t until September 2015 that researchers were able to prove their existence.
Incredibly sensitive apparatus in the United States detected gravitational waves rippling across the universe from the catastrophic collision over 0.2 seconds of two black holes which actually occurred 1.3 billion years ago but whose signals took that long to reach Earth.
The arrival of the perturbations at the Laser Interferometer Gravitational-Wave Observatory in the US was marked by a change in the length of a four-kilometrelong laser arm by one-thousandth of the width of a proton – which scientists say is equivalent to altering the distance to the closest star beyond the Solar System by a hair’s width.
Beyer is a member of the university’s mathematical and computational gravity group, which has spent several years focusing on Einstein’s theory of gravitation.
‘‘We don’t really know the laws of physics which describe the extreme conditions of the early universe in all detail. Nevertheless, cosmologists have been able to develop models over the last few decades, based on the theory of general relativity. The so-called ‘concordance model’ has proved to be extremely successful.
‘‘Inflation is a period in the history of the universe characterised by extremely rapid expansion, and is one of the cornerstones of the concordance model.’’
Beyer and LeFloch have recently performed model calculations which, for the first time, take a particularly mindboggling effect predicted by Einstein’s equations near the Big Bang into account.
This effect can have ‘‘significant consequences’’ for the matter at the 10 to the power of minus 36 seconds.
‘‘When we imagine we are going backwards in time towards the Big Bang, the matter in our universe is not just simply squashed and squeezed into smaller and smaller regions of space, as assumed in the concordance model for simplicity.
‘‘Instead, according to Einstein’s beautiful but highly complex equations, the trip towards the Big Bang backwards in time turns out to be more like riding an aeroplane undergoing increasingly severe turbulence. Everything inside the aircraft is shaken up, generating more and more chaos while being more and more squashed.
‘‘The imprints of this in the gravitational-wave spectrum could potentially still be observable in the present universe,’’ Beyer said.
‘‘While the simple description of the dynamics at the Big Bang in the concordance model is compatible with the equations of general relativity, the theory suggests that the conditions at the Big Bang must necessarily be extremely fine-tuned in a certain way.
‘‘We don’t know how the universe was created, whether it was a random act or whether it followed some deeper logic which we don’t understand yet. But if it was a random act, it would be extremely unlikely that the early universe dynamics would be described accurately by the concordance model.
‘‘Eventually, the final aim of our work is to understand how the universe was created.’’
To make Einstein’s general theory of relativity equations fit with the concordance model, they had to be simplified.
Unfortunately, that loss of precision was akin to ‘‘looking at the stars through a blurred telescope’’, Beyer said.
‘‘With these gravitational waves, we will be able to see the universe on a much more fine scale, and therefore be able to focus a bit more.
‘‘Gravitational waves are the only conceivable source of information about the Big Bang. Electromagnetic waves, light waves, cannot penetrate the opaque-matter plasma of the early universe. In fact, the universe only became transparent about 300,000 years ago after the Big Bang.
‘‘When we started this project, we didn’t know what to look for. The particular behaviour of the cosmological matter in the early universe was not something that we expected.
‘‘It seems fair to say the cosmos and Einstein’s theory are far too complicated for simple answers.’’ ❚ Paul Gorman is a senior communications adviser at the University of Otago.