Exploring the First Microsecond of the Cosmos

James Maynard
May 28 · 4 min read

The first microsecond of the Cosmos was filled with a weird quark-gluon plasma soup. Turns out, things may have been weirder than that.

Integration of the Inner Tracker inside ALICE at CERN. Image credit: Maximilien Brice/CERN

In the instant after the Big Bang, matter as we know it did not exist — the Cosmos was filled with a soup of subatomic particles. Astronomers and astrophysicists are now able to piece together large pieces of the history of the early Universe. But, significant questions remain concerning the processes by which energy transformed to a weird quark-gluon plasma, eventually forming stars and planets and galaxies.

Researchers from University of Copenhagen set out to better-understand the nature of this quark-gluon plasma (QGP). (Quarks are the constituent pieces of protons and neutrons at the center of atoms, while gluons hold them together.)

“First the plasma that consisted of quarks and gluons was separated by the hot expansion of the universe. Then the pieces of quark reformed into so-called hadrons. A hadron with three quarks makes a proton, which is part of atomic cores. These cores are the building blocks that constitutes earth, ourselves and the universe that surrounds us,” You Zhou, Associate Professor at the Niels Bohr Institute, University of Copenhagen, explains.

“Protomatter — an unstable substance which every ethical scientist in the galaxy has denounced as dangerously unpredictable.” – Saavik, Star Trek III: The Search for Spock

A look at how the Cosmos changed over time since the Big Bang. Note the “quark soup” on the left-hand side. Ideas of this era of the Universe just got a little more soupy. Image credit: NASA/CXC/M. Weiss

The quark/gluon plasma filled the Universe for first microsecond of the Cosmos, following the Big Bang.

As the Universe expanded and cooled, the strange mixture of quarks and gluons quickly transformed into more recognizable (if still structureless) matter.

“One of the fundamental questions in the phenomenology of quantum chromodynamics is what are the properties of matter at extreme densities and temperatures where quarks and gluons are in a state of matter called the quark–gluon plasma (QGP). High-energy heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) at BNL and the Large Hadron Collider (LHC) at CERN create such a state of strongly interacting matter allowing us to study its properties in the laboratory,” researchers explain in an article published in Physics Letters B.

Today, the we never see quarks or gluons outside subatomic particles.

“Each atom contains a nucleus composed of protons and neutrons (except hydrogen, which has no neutrons), surrounded by a cloud of electrons. Protons and neutrons are in turn made of quarks bound together by other particles called gluons. No quark has ever been observed in isolation: the quarks, as well as the gluons, seem to be bound permanently together and confined inside composite particles, such as protons and neutrons,” CERN researchers describe.

Using the Large Hadron Collider at CERN, researchers smashed lead ions together at nearly the speed of light, allowing them to recreate conditions during first microsecond of the Cosmos. These collisions were then analyzed, using a new algorithm to study more particles at once than ever before possible.

ALICE is housed within Point 2 in the LHC tunnel at CERN. Image credit: Mona Schweizer/CERN

“To recreate conditions similar to those of the very early universe, powerful accelerators make head-on collisions between massive ions, such as gold or lead nuclei. In these heavy-ion collisions the hundreds of protons and neutrons in two such nuclei smash into one another at energies of upwards of a few trillion electronvolts each. This forms a miniscule fireball in which everything “melts” into a quark-gluon plasma,” researchers at CERN explain.

Within a small fraction of a second, these quarks and gluons (collectively known as partons) combine into protons, neutrons, and a flurry of more exotic particles. These particles then quickly race apart from each other.

Previously, astrophysicists thought of the QGP as being similar to a gas. But, this new study suggests the QGP was more fluent — having conditions more akin to water. For a brief instant before the QGP cooled into hadrons, atoms, and penguins, a water-like proto-matter may have filled the Cosmos.

This finding could assist physicists to better understand the critical first stage of matter in the ancient Cosmos, as well as our Universe today.

James Maynard is the founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat.

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