Try out the possibility of models of gravity differently general relativity possibly closer to home than we think. A team of researchers has suggested that we might be able to use seismic movements in the Earth itself to test for altered gravity.
We don’t understand 95 percent of the content of the universe. The unknowns collectively known as the dark sector encompass both Dark matter And dark energy.
Dark matter appears to be the dominant form of matter in the universe, with each galaxy containing up to 80 percent of this invisible form of matter. Meanwhile, dark energy is an energy source that permeates all spacetime and is responsible for the accelerated expansion of the cosmos.
But saying that dark matter and dark energy are physical entities rests on the assumption that our understanding of gravity is correct. Currently, our best understanding of gravity comes from Einstein general theory of relativity. This theory tells us that gravity is the manifestation of the curvature and curvature of spacetime itself.
But we know that general relativity is incomplete. We know it’s collapsing in the centers black holes and at the beginning of the universe. So we know we don’t have the whole history of gravity on our hands yet.
Motivated by this, many people over the decades have proposed theories of modified gravity, which are a number of extensions and refinements of Einstein’s original model.
However, all of these extensions are preceded by a number of difficult hurdles. We have tested general relativity in many contexts and on many scales, so it is difficult to construct a theory that differs significantly enough from simple general relativity to possibly explain away dark matter and dark energy, and yet still satisfies all known observational limitations .
The more ways we can devise to study modified gravity, the better. And that’s how a team of researchers found that we don’t have to look at the stars to test different modified theories of gravity. We can look down at the earth instead. They discovered that under modified gravity, seismic waves travel through the earth at different speeds and in different ways.
Because we know so many of the Earth’s properties so well, such as its mass and moment of inertia, we can reverse that knowledge to use seismic data to constrain modified theories of gravity.
So far, the data do not indicate a need to deviate from Einstein’s original work. But the more tools we develop and the more opportunities we can seek, the better.
This article was originally published by universe today. read this original article.
