Long before Earth formed, the Universe was awash with liquid. In the first second after the Big Bang, a scorching hot sea of light and particles filled the Universe.
This primordial goo was made up of quarks, which are the building blocks of matter, and gluons, massless particles that bind quarks together.
Over the last two decades, scientists have managed to recreate this liquid light – known as quark-gluon plasma – and study its properties.
They’ve discovered that strong interactions between quarks and gluons meant that the plasma would have flowed like water. With low viscosity and almost no resistance to flow, this liquid was unlike any other substance known to science.
As the Universe expanded, the plasma gradually cooled, forming a hot, dense, ionised gas that scattered and trapped light for the next 370,000 years.
