Scientists have created a computer simulation that produces a realistic picture of the evolution of the universe, starting from just after the Big Bang to the present, compressing the 13.7 billion years into just over two minutes.
You can read the paper by the simulation’s authors here. Here’s the abstract.
Previous simulations of the growth of cosmic structures have broadly reproduced the ‘cosmic web’ of galaxies that we see in the Universe, but failed to create a mixed population of elliptical and spiral galaxies, because of numerical inaccuracies and incomplete physical models. Moreover, they were unable to track the small-scale evolution of gas and stars to the present epoch within a representative portion of the Universe. Here we report a simulation that starts 12 million years after the Big Bang, and traces 13 billion years of cosmic evolution with 12 billion resolution elements in a cube of 106.5 megaparsecs a side. It yields a reasonable population of ellipticals and spirals, reproduces the observed distribution of galaxies in clusters and characteristics of hydrogen on large scales, and at the same time matches the ‘metal’ and hydrogen content of galaxies on small scales.
Elizabeth Gibney has more on how it was done. The point is that the simulation is not merely descriptive in that they just created pretty pictures for what we know about the evolution of the universe. What they did was to input the information we have about the universe at just 12 million years of age and see how well its subsequent evolution matches what we observed.
Mark Vogelsberger, a physicist at the Massachusetts Institute of Technology in Cambridge, and his colleagues created a model of the Universe that follows the evolution of both visible and dark matter starting just 12 million years after the Big Bang (see video). While previous models have either been small and detailed or large and coarse, this simulation covers a region of space big enough to be representative of the whole Universe — a cube 106.5 megaparsecs (350 million light years) across — but is detailed enough to resolve small-scale structures, such as individual galaxies. Unlike previous simulations, it produces a mixture of galaxy shapes that fit observations well. Its also accurately recreates the large-scale distribution of galaxy clusters and neutral gas in the Universe, as well as the hydrogen and heavy element content of galaxies.
Only in recent years has it been possible to use this model to simulate galaxies that match a range of observed properties. That Vogelsberger and his colleagues’ model reproduces the variety of galaxy types seen in the real Universe puts the standard model on firmer ground, says Brook. From now on, such simulations will become much more useful for predicting and interpreting observational results, he adds.
Although the model agrees well with observations of the Universe, it does have anomalies. For example, it shows low-mass galaxies building up too early. “The idea now is to try to understand why this is happening and see what we are missing in terms of galaxy formation,” says Vogelsberger.