The Universe 100,000 years after the Big Bang

The furthest look back through time yet – 100 years to 300,000 years after the Big Bang – has provided enticing new clues as to what might have happened.

U.S. researchers have conducted an extensive analysis of the thermal radiation left over from the Big Bang, also known as cosmic microwave background (CMB) radiation.

Their analysis supports the theory that the Big Bang occurred between 13.798 and  0.037 billion years ago, creating our subsequent Universe.

U.S. researchers have conducted an extensive analysis of the thermal radiation left over from the Big Bang, also known as cosmic microwave background (CMB) radiation. The structure of the CMB, the oldest light in the universe, is displayed in the high-latitude regions of the map. The central band is the plane of our Galaxy

‘We found that the standard picture of an early universe, in which radiation domination was followed by matter domination, holds to the level we can test it with the new data,’ said Eric Linder, a theoretical physicist at the Lawrence Berkeley National Laboratory.

But there are hints that radiation didn't give way to matter exactly as expected,’ he added.

‘There appears to be an excess dash of radiation that is not due to CMB photons.’

Currently, our knowledge of the Big Bang and the early formation of the universe stems almost entirely from measurements of the CMB.

These are primordial photons set free when the universe cooled enough for particles of radiation and particles of matter to separate.

The elusive subatomic neutrino tracks showing electrons and muons caught in a nano second. Neutrinos are the second most populous residents of today's universe, after photons

These measurements reveal the CMB's influence on the growth and development of the large-scale structure we see in the universe today.

Using the latest satellite data from the European Space Agency's Planck mission and NASA's Wilkinson Microwave Anisotropy Probe (WMAP), Linder, working with Alireza Hojjati and Johan Samsing, analysed CMB measurements to higher resolution, lower noise, and more sky coverage than ever before.

‘With the Planck and WMAP data we're really pushing back the frontier and looking further back in the history of the universe, to regions of high energy physics we previously could not access,’ said Linder.

‘While our analysis shows the CMB photon relic afterglow of the Big Bang being followed mainly by dark matter as expected, there was also a deviation from the standard that hints at relativistic particles beyond CMB light.’

This map shows the oldest light in our universe, as detected with the greatest precision yet. The ancient light, called the cosmic microwave background, was imprinted on the sky when the universe was 370,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities

Linder suggests the reason behind these relativistic particles are early versions of neutrinos, the phantom-like subatomic particles that are the second most populous residents of today's universe.

Another theory is dark energy, the anti-gravitational force that accelerates our universe's expansion.

‘Early dark energy is a class of explanations for the origin of cosmic acceleration that arises in some high energy physics models,’ said Linder.

‘While conventional dark energy, such as the cosmological constant, are diluted to one part in a billion of total energy density around the time of the CMB's last scattering, early dark energy theories can have 1-to-10 million times more energy density.’

Linder believes early dark energy could have been the driver that seven billion years later caused the present cosmic acceleration.

Its actual discovery would not only provide new insight into the origin of cosmic acceleration, but perhaps also provide new evidence for string theory and other concepts in high energy physics.

‘New experiments for measuring CMB polarisation that are already underway, such as the POLARBEAR and SPTpol telescopes, will enable us to further explore primeval physics,’ Linder said.