Ultra-high-resolution simulations of a tiny slice of the universe – a million times smaller than a proton – have revealed the very first structures that ever existed. And these dense structures are strange.
The first trillionths of a second after Big explosionThe universe was a hot, liquid place, a place heated to a trillion degrees. Although scientists cannot directly observe this moment in time, they can reconstruct it using powerful computer simulations.
New simulations, more detailed than ever before, showed how, in these early cases, gravity caused quantum particles known as inflatons to stick together. The results showed for the first time how these clumps then formed complex and dense structures that weighed from a few grams to 20 kilograms – about heavier than a postage stamp, but lighter than a bulldog – packed in a space smaller than a particle.
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The simulation is the first to show enough detail for scientists to decipher the range of sizes and shapes of these children’s structures. In addition, the results elegantly fit a simple theoretical model that is nearly 40 years old, said study co-author Richard Easter, professor of physics at the University of Auckland.
“We are discovering this incredibly complex phase in a very early universe that is just beginning to be understood correctly.”
The simulation simulated the end time of inflation, a period when the universe was expanding dramatically in size. At that time, the universe contained only energy and inflatons – a type of quantum matter formed from the energy field that filled all space after the Big Bang.
Physicists believe that the inflaton structures seen in simulations arose from fluctuations in this energy field just after the Big Bang. This same field likely created the large-scale galactic structures visible in the universe today, billions of light-years across.
The dense, inflaton-filled structures seen in the simulations probably did not last long, as they probably turned into elementary particles in a fraction of a second. But because of their high density – reaching 100,000 times the density of the surrounding space – their movements and interactions could cause ripples in the fabric of space-time called gravitational waves. The new simulations will help scientists calculate exactly how large these gravitational waves could have been, which will help future experiments look for similar waves in the universe.
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Small lumps could also collapse under their own weight, creating the first black holes in the universe, called primordial black holes. Some scientists believe that such black holes could be a candidate for dark matter – a mysterious substance that no one has seen directly, but which today makes up 85% of the matter in the universe. Physicists have not seen any black holes in their simulations, but they plan to do longer, more detailed simulations in the future that could show such objects.
“Primitive black holes represent an intriguing opportunity at this stage – they can lead to new behavior, but also provide new opportunities for model testing,” Easter wrote in an email to Live Science. Since some primordial black holes must persist in the modern universe, their discovery could help test scientists’ models of these early moments in the infancy of the universe.
Easter and colleagues published a paper describing the simulation on March 22 in Physical Review D.
Originally published Living Science…