What is the ekpyrotic Universe theory? Ekpyrotic cosmology is an alternative theory to the standard theory of cosmology, which is known as the Lambda-CDM, or ΛCDM model.
In the ΛCDM model, the remarkable flatness of the Universe requires a period of rapid ‘inflation’, which smooths out the early variations in density and temperature.
Although there is no direct proof of this inflation, or a likely cause, it neatly explains many complicated aspects of the Universe we see today, and is perfectly consistent with current observations.
In ekpyrotic theory, however, there is no beginning of time, and the Big Bang is replaced with a ‘bounce’ between two ‘branes’ – three-dimensional worlds in a five-dimensional space-time.
The structure of the current Universe is determined before this bounce, so the need for inflation is avoided.
The theory also avoids the inconvenient ‘singularity’ built in standard Big Bang cosmology. But the theory isn’t perfect. It seems to generate negative-energy particles, which would destroy the Universe.
There are also other differences in the predictions of ekpyrotic and ΛCDM theories, such as the form of the gravitational wave background (random ripples in space-time potentially caused by the force of the Big Bang), the distribution of galaxies and the existence of so-called ‘ghost particles’.
But, currently, there is no observational evidence to support the ekpyrotic theory over ΛCDM cosmology.
So, while the theory is an intriguing alternative, the standard Big Bang model of cosmology is currently the most accepted theory amongst physicists.
This article is an answer to the question (asked by Luis Doyle, via email) 'What is the ekpyrotic universe theory?'
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