Physicists Find No Sign of The Particle That Made The Universe Explode

So what caused it?
LHCb Collaboration, CERN
A recent attempt to find a theoretical particle responsible for the Universe's early rapid expansion has come up empty handed, throwing a question mark over whether it really exists.

While there is still a low chance that the particle could be heavier than expected, or look a little different, physicists are preparing themselves for going back to the drawing board on one of the Universe's biggest mysteries.

Physicists from the Institute of Nuclear Physics at the Polish Academy of Sciences and the University of Zurich hunted for traces of a light form of a particle dubbed the inflaton in data collected during experiments using the Large Hadron Collider at CERN near Geneva in 2011 and 2012.
Much as its name suggests, inflatons are particles that, well, inflate space.

To be more precise, it helps to know why we're looking for them in the first place.
When we look up in the sky and measure the haze of microwave radiation, we find there's a background static that looks eerily the same no matter which way we look.

This background radiation, or cosmic microwave background, is the remnants of light that existed when the Universe was still just a few hundred thousand years old and not yet cool enough for particles to form.

As the Universe expanded, the radiation stretched into microwave lengths, which we can still see.
But given the scale of space, and the fact light from one side of the Universe hasn't yet had had time to make it to the other side, it seems odd that all of the light is spread out in such a similar way.
"When we look into the sky, the deep space fragments visible in one direction may be so distant from those visible in another direction that light has not yet had time to pass between them," researcher Marcin Chrzaszcz from the Polish Academy of Sciences explained.

"So nothing that has happened in one of these areas should affect the other. But wherever we look, the temperature of distant regions of the cosmos is almost identical! How could it have become so uniform?"

In 1981, a physicist by the name of Alan Guth suggested if the Universe grew rapidly for a short amount of time while still young and hot, the background radiation would still reflect that uniformity.
That period of rapid inflation would definitely explain what we see, but such a force requires a field to push, and all fields have particles to carry that information.

Enter the inflaton – a theoretical particle that would have shoved space to a gargantuan size in a fraction of a second before leaving the Universe expand far more gradually under its own cosmological constant.

Much like its famous cousin the Higgs boson, the inflaton (if it exists) would be too fleeting to be directly observable.

In fact, it was suggested at one point that the Higgs particle was in fact the inflaton in disguise.
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