TO COOK up planets, stars and people, the universe had to be preheated.
In the first slivers of a second after the big bang, the universe expanded exponentially in a process called inflation, leaving the cosmos empty and cold. "Inflation is a flash-freezer," says John Giblin of Kenyon College in Gambier, Ohio. A few minutes later, energetic photons were zipping through a dense cauldron of radiation at a searing 1010 kelvin, the first stage in a cascade of events that gave rise to the matter we have today. So where did all the heat come from?
The energy that drove inflation is one option, but it would have been trapped in a field when the process ended. In the 1980s, physicists suggested that this "inflaton field" decayed into radiation, infusing the universe with heat. But models show the process would have been too slow to make all the matter we see.
Another way to get at the trapped energy is to introduce a second field – either a known kind or a theoretical newcomer – that could couple to the inflaton field. The resulting resonance would let energy shake free from the inflaton field and form energetic particles, similar to the way sound waves at a resonant frequency can make glass vibrate until it breaks.
These models, called preheating, were better at releasing radiation, but only got about half of the energy required out of the field.
Giblin and his student J. Tate Deskins have produced the most efficient preheating model yet by finding a way to couple the inflaton to the electromagnetic field. This dumps energy directly into photons.
Their simulations show that the inflaton field could deposit 96 per cent of its energy into photons this way (arxiv.org/abs/1305.7226v1). That is enough to ensure that the early universe is dominated by radiation, as predicted, says Giblin.
Alan Guth of the Massachusetts Institute of Technology says if photons received the inflaton energy, they could have left a pattern in primordial magnetic fields, offering a way to test the model.
This article appeared in print under the headline "To bake matter, first preheat the universe"
- New Scientist
- Not just a website!
- Subscribe to New Scientist and get:
- New Scientist magazine delivered every week
- Unlimited online access to articles from over 500 back issues
- Subscribe Now and Save
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.
Have your say
Only subscribers may leave comments on this article. Please log in.
Only personal subscribers may leave comments on this article
All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.
If you are having a technical problem posting a comment, please contact technical support.
