Dark Energy Is Dynamic, Researchers Find; Could Disprove Einstein’s Cosmological Constant

A team of scientists has found that the nature of dark energy may not follow the cosmological constant set by Albert Einstein 100 years ago.

The findings published in the Cornell University Library found that previous predictions about the nature of dark energy where it had no dynamic features could be wrong. According to the study, the team from the University of Portsmouth and the National Astronomical Observatories of China (NAOC), dark energy was found to be a dynamic field instead of the previously assumed vacuum energy which had no dynamic properties.

Professor Gong-Bo Zhao, lead author of the study from the Institute of Cosmology and Gravitation (ICG) at the University of Portsmouth and the NAOC, said in a Science Daily report that "We are excited to see that current observations are able to probe the dynamics of dark energy at this level, and we hope that future observations will confirm what we see today."

The discovery of the presence of dark matter by Einstein introduced it to the world and our information about dark matter hasn’t improved much since, co-author professor Bob Nichol, director of the ICG said. The new study helps shed light on the century-long dark energy mystery.

Figuring out the nature of dark energy has been a key goal for modern day scientists. The physical property of dark energy is given by its Equation of State (EoS). It is the ratio of pressure and energy density of dark energy.

The old Lambda-Cold Dark Matter (LCDM) model furthered Einstein's cosmological constant. It was based on the assumption that dark matter was static in nature. This constant is nothing but the energy held by the vacuum of space. The effect vacuum has on other objects with a constant EoS of -1 given by LCDM. The fallacy of this model lies in its assumption that dark energy has no dynamic features according to the new study.

A team led by professor Zhao, in collaboration with the Sloan Digital Sky Survey III (SDSS-III BOSS), which is a survey to measure the spatial distances between luminous galaxies, successfully measured the Baryonic Acoustic Oscillations (BAO) at multiple cosmic epochs with a high precision in 2016. BAO is the periodic fluctuation in the density of Baryonic matter. It is used as a cosmological scale to measure the length of objects in space.

The team used these measurements to prove that dark energy is dynamic. The level of significance was found to be 3.5 sigma. Sigma signifies velocity dispersion in astronomy. A positive reading points to a dynamic moving dark energy, not a static vacuum energy as previously assumed.

A Dark Energy Spectroscopic Instrument (DESI) survey, is looking to begin creation of a 3D cosmic map by 2018. If this project takes off, the team says the future looks good for dark energy research. These large surveys will provide datasets which will give us crucial information about the behavior of dark matter and help us establish with certainty if dark matter is, in fact, dynamic or not.

Professor Nichol added that "This work is the culmination of many years of work in collaboration between scientists in China and the UK. Gong-Bo is one of our brightest stars holding a joint position between NAOC and here at the ICG."