Newton’s 300-year-old law just passed its biggest test yet
Astronomers using the Atacama Cosmology Telescope have conducted a large-scale test of gravity across galaxy clusters. The results confirm that gravity behaves according to the laws established by Newton and Einstein, even at massive cosmic distances.
Why it matters
Confirming these laws at extreme scales helps cosmologists narrow down the mystery of dark matter versus the need for modified gravity theories.
Gravity is best known as the force that pulls objects toward Earth, but its role extends far beyond falling apples. Across the universe, gravity acts as an invisible framework that influences how galaxies, galaxy clusters, and the largest cosmic structures form and evolve.
For decades, however, astronomers have faced observations that do not seem to fit neatly with what can be seen. Some stars and galaxies move much faster than their visible mass appears capable of explaining. That mystery has led cosmologists such as University of Pennsylvania researcher Patricio A. Gallardo to investigate whether the laws of gravity established by Isaac Newton and Albert Einstein remain valid everywhere in the universe.
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