So precise that they have almost no effect on the subatomic level, however, gravity keeps planets in orbit and collects beams of millions of stars that astronomers know as galaxies. Although invisible to the human eye, gravity also remains capable of faking light, the fastest-moving physics-controlled factor in existence in our universe.
The most accurate description of gravity remains the one given to us by Einstein in 1915 with his general theory of relativity. For Einstein, gravity is basically just the effect that arises from differences in the distribution of mass throughout the universe, causing space-time to curvature. Think of how a piece of marble, placed at one end of a large rubber slab, can roll toward a place where you place a larger, heavier object that weighs the paper, creating a downward curving curve along its surface. Although gravity is actually the force that moves the marble in this analogy, the broader concept is about how smaller objects in space are attracted to objects of greater mass.
Although Einstein’s understanding of gravity is still the best we currently have, There were challenges sometimes for the theories of the famous physicist. However, according to New studyReviewing Einstein’s theories about the most mysterious force in all of nature is unlikely to help us solve one of the greatest lingering questions about our universe: what is causing it to expand at an ever-accelerating rate?
Scientists have long pondered what could cause our universe to expand the way it does, seemingly avoiding the effect of gravity. The effect can be compared to what would happen if you threw a baseball straight into the air, and instead of rising to a certain height and falling again, it kept going up instead, gaining speed as you moved away from the ground. In other words, the expansion of our universe seems to defy everything we understand about gravity.
Enters dark energyThe hypothetical force that physicists believe is driving this anomalous global expansion. The source of nearly 70% of all energy in our universe today, since the 1990s, dark energy has been the main explanation for what could cause the universe’s expansion rate to continually accelerate.
However, other possibilities exist as well. What if, for example, something was incomplete in our understanding of gravity? Was Einstein wrong?
This was one of the questions on the minds of researchers with the International Dark Energy Survey, which was based on data collected by the Victor M telescope. Cut into the gravity puzzle.
The study addressed the problem by exploring several different possible global models. This included the widely accepted presence of dark energy, as well as sterile neutrinos or nonzero spatial curvature as possible explanations. Ready to potentially alter Einstein’s general theory of relativity, if necessary, the team also examined the possibility that “adjustments to the physics of gravity” would be needed. The team used simulated data combined with blind analyzes of real data to help validate its findings, which aim to determine whether our ideas about dark energy and an expanding universe could arise from a fundamental misunderstanding about the relationship between gravity and the universe.
“This potential misunderstanding may help scientists explain dark energy,” he recently read statement On the Jet Propulsion Laboratory website. Citing NASA scientists among its contributors, the statement added that the study, “one of the most accurate tests to date of Albert Einstein’s theory of gravity at cosmological scales,” found that our accepted understanding of how gravity works remains intact.
Specifically, the Dark Energy Survey team has been looking for evidence that there can be differences in the strength of gravity either across the history of the universe or across great distances in our universe. Such a discovery would be a clear indication that Einstein’s theories were far from complete, and thus would explain the anomalous expansion of the universe.
Based on the results of the team’s analysis, it appears that the observations still largely work in tandem with Einstein’s theory of gravity. However, while the relativistic explanation for gravity is still the best model, this does not bring us any closer to explaining dark energy.
Scientists know that dark energy exists, although we have not yet determined what it is made of, due to the effect of its own gravity on the space around it. While light does not interact with dark energy, it can be distorted by gravity where there are large concentrations of it, causing distortions of light in images collected from distant galaxies – an effect also known as weak gravitational lensing.
After measuring the shape and appearance of more than 100 million galaxies, the Dark Energy Survey team found that all of their observations were supplemented by Einstein’s predictions about gravity.
“The work helps pave the way for two upcoming space telescopes that will probe our understanding of gravity at a higher resolution than the new study,” reads the JPL statement, “and may eventually solve the mystery.”
In the coming years, two new missions – the European Space Agency’s Euclid mission, as well as the launch of NASA’s Roman Nancy Grace space telescope – will aim to further probe the universe for evidence of whether there are cases where the force of gravity appears to differ. Although the latest study by the Dark Energy Survey relied on data released nearly five billion years into the past, Euclid and Nancy Grace Roman will look even further back — up to eight billion and 11 billion years, respectively. .
While the latest study found that Einstein’s theory of gravity was able to meet the challenges of one of its greatest tests to date, that doesn’t mean future discoveries can’t reveal areas where some work still needs to be done.
“There is still room to challenge Einstein’s theory of gravity,” said Agnes Ferti, a postdoctoral researcher at JPL and one of the study’s co-authors. With more accurate measurements being collected in the future, Ferti thinks some aspects of Einstein’s theory may still require a little revision.
“It is therefore imperative that we continue to collaborate with scientists around the world on this problem as we did with the dark energy survey,” Verti adds.
A draft version of the team’s 45-page paper, “Results of the Third Year Dark Energy Survey: Extension Constraints for ΛCDM with Weak Lens and Galactic Clustering,” It can be read online here.