New findings on dark energy question Einstein's cosmological constant - SFU study

January 05, 2018

An international study co-led by SFU physicist Levon Pogosian has revealed that dark energy, widely thought to be the cosmological constant posited by Albert Einstein, may not be constant after all. Dark energy is the mysterious energy of empty space that makes up 70 per cent of the universe and provides the force that accelerates the expansion of the universe.  Scientists have been trying to understand this mystery since the discovery of cosmic acceleration in 1998.

“Dark energy has no effect on our daily experiences, but it’s extremely powerful when it comes to the entire universe,” says Pogosian. “The fate of space-time depends on how dark energy will evolve. “

In the study, published by Nature Astronomy, Pogosian and researchers from other institutions analyzed several data sets to measure the evolution of dark energy density over the course of cosmic history. Their findings suggest that dark energy density has not stayed constant but instead increased with time.

“The phenomenon of dark energy is intimately tied to a significant gap in our understanding of gravity and its connection to quantum physics. The evidence for dynamical dark energy is still not sufficiently strong to rule out the cosmological constant. But if dark energy happens to evolve as we find, it would imply a correction to Einstein’s theory of general relativity and could help us find the theory of quantum gravity.”

The researchers are hoping their findings will be confirmed by the Dark Energy Spectroscopic Instrument (DESI) survey, which will start taking data from its location at the Kitts Peak Observatory in Tuscon, Arizona in 2018.

Fast Facts:

  • In 1917, Albert Einstein introduced the cosmological constant so that his theory of general relativity could describe a static universe. However, the universe was found to be expanding.
  • In 1998, it was discovered that the universe is not just expanding, but its expansion is accelerating. Dark energy has since remained a mystery to physicists.
Link to study