Space-time waves can give clues to the missing elements of the universe

Is a little far from the principle of our universe. Almost everything fits, but the cosmic ointment has a fly, the infinite sandwich has a grain of sand. Some scientists believe that the culprit may be gravity – and that it may help us to find the missing part from the microscopic ripples in the space-time fabric.

A new paper co-authored by a University of Chicago scientist demonstrates how this works. Published December 21 Physical Review d, The method is based on finding such ripples that are orbited by traveling through supermassive black holes or large galaxies on Earth’s path.

The problem is that something is expanding the universe, but expanding faster and faster over time – and no one knows what it is. (The discovery of a fixed rate is an ongoing discussion in cosmology).

Scientists have proposed all sorts of theories as to what the missing part might be. “A lot of this depends largely on changing the way gravity,” said Jose Maria Izquaga, author of a paper from NASA’s Einstein Postcontroller at the Cowley Institute for Cosmological Physics in USCA. “So gravitational waves are the perfect messenger to see if these potential changes in gravity exist.”

Gravitational waves are the ripples of space-time itself; Since 2015, humanity has been able to select these ripples using LIGO Observatories. Whenever two massive objects collide somewhere else in the universe, they form a ripple that travels through space, with the signature that it creates – perhaps two black holes or two neutron stars colliding.

In the paper, Izquiaga and co-author Miguel Zumalikaregui have argued that if such waves hit a supermassive black hole or cluster of galaxies on their way to Earth, the signature of the wave would change. If there was a difference in gravity compared to Einstein’s theory, the evidence would be embedded in that signature.

For example, one theory for the missing part of the universe is the existence of an extra particle. Such particles will, among other effects, produce a kind of background or “medium” around large objects. If a traveling gravitational wave hits a supermassive black hole, it produces waves that merge with the gravitational wave. Depending on what is encountered, the signature of the gravitational wave can carry an “echo” or show a scramble.

“This is a new way of testing scenarios that can’t be tested before,” Izquaga said.

Their paper outlines the terms of how such effects can be detected in future data. The next LIGO run is set to begin in 2022, with an upgrade to make detectors already more sensitive.

“During our last observation with LIGOs, we saw new gravitational waves reading every six days, which is amazing. But across the universe, we think they actually happen once every five minutes,” Izquiga said. “In the next upgrade, we could see as many as hundreds of events each year.”

He said the increased number would make it more likely that one or more waves would have passed through a larger object, and that scientists would be able to analyze it for signs of missing components.

Zumalkareregui, another author on the paper, is a scientist at the Max Planck Institute for Gravitational Physics in Germany as well as the Berkeley Center for Cosmological Physics at the Lawrence Berkeley National Laboratory and the University of California, Berkeley.