Across cosmic history, powerful forces have acted on matter, reshaping the universe into an increasingly complex web of structures. Now, new research led by Joshua Kim and Mathew Madhavacheril at the University of Pennsylvania and their collaborators at Lawrence Berkeley National Laboratory suggests our universe has become “messier and more complicated” over the roughly 13.8 billion years it’s been around, or rather, the distribution of matter over the years is less “clumpy” than it should be expected.

“Our work cross-correlated two types of datasets from complementary, but very distinct, surveys,” says Madhavacheril, “and what we found was that, for the most part, the story of structure formation is remarkably consistent with the predictions from Einstein’s gravity. We did see a hint for a small discrepancy in the amount of expected clumpiness in recent epochs, around four billion years ago, which could be interesting to pursue.”

The data, which was published in the Journal of Cosmology and Astroparticle Physics and the preprint server arXiv, comes from the Atacama Cosmology Telescope’s (ACT) final data release (DR6) and the Dark Energy Spectroscopic Instrument’s (DESI) Year 1.

High-Speed Cosmic Kick: A New Black Hole Discovery

A newly formed black hole recently received a high-speed “kick,” thanks to gravitational waves, which propelled it at about 5 million kilometers per hour—roughly 200 times the speed of light. This surprising discovery was made through data collected by gravitational wave observatories LIGO and Virgo. These observatories detected spacetime ripples produced by the coalescence of two black holes on January 29, 2020, revealing the large recoil effect.

For the first time, scientists have measured the early universe running in extreme slow motion, showing that time was five times slower just a billion years after the Big Bang. By studying nearly 200 quasars – hyperactive supermassive black holes at the centers of ancient galaxies – researchers have provided new evidence for Einstein’s theory of general relativity regarding an expanding universe.

The Mystery of Early Universe Time Dilation

Einstein’s general theory of relativity predicts that, as the universe expands, distant objects (and therefore the early universe) should appear to experience slower time. However, directly observing this has been challenging due to the vast distances and the faint signals coming from early cosmic phenomena. Previous research had established this dilation back to half the age of the universe using supernovae, but quasars have now pushed this further back to just a tenth of the universe’s age.