A study of 200,000 galaxies found they had lost half their energy in just 2 billion years.
According to a report by an international team of astronomers, the energy produced in a section of the universe today is only about half what it was two billion years ago. This fading is occurring across all wavelengths from the ultraviolet to the far infrared. The universe is slowly dying, the researchers say.
The team studied more than 200,000 galaxies to measure the energy generated within a large portion of space. The survey data includes measurements of the energy output of each galaxy at 21 wavelengths, from the ultraviolet to the far infrared. This study, part of the Galaxy And Mass Assembly (GAMA) project, the largest multi-wavelength survey ever put together, involved many of the world’s most powerful telescopes and represents the most comprehensive assessment of the energy output of the nearby universe.
All the energy in the universe was created in the Big Bang, with some portion locked up as mass. Stars shine by converting mass into energy, as described by Einstein’s famous equation E=mc2. The GAMA study sets out to map and model all of the energy generated within a large volume of space today and at different times in the past. Simon Driver of the University of Western Australia led the large GAMA team. Driver said:
While most of the energy sloshing around in the universe arose in the aftermath of the Big Bang, additional energy is constantly being generated by stars as they fuse elements like hydrogen and helium together.
This new energy is either absorbed by dust as it travels through the host galaxy, or escapes into intergalactic space and travels until it hits something, such as another star, a planet, or, very occasionally, a telescope mirror.
The concept that the universe is slowly fading has been known since the late 1990s, but this work shows that it is happening across all wavelengths from the ultraviolet to the infrared, representing the most comprehensive assessment of the energy output of the nearby universe. Driver said:
The universe will decline from here on in, sliding gently into old age. The universe has basically sat down on the sofa, pulled up a blanket and is about to nod off for an eternal doze.
The team presented this work at the International Astronomical Union XXIX General Assembly in Honolulu, Hawaii, August 10, 2015.