“You can journey to the ends of the earth in search of success,” 19th-century Baptist preacher Russell Conwell is said to have proclaimed, “but if you’re lucky, you will discover happiness in your own backyard.”
Modern cosmology has stepped far beyond our cosmic backyard. We peer into the light from the earliest moments of the big bang. Our surveys stride across the universe, swallowing millions of galaxies at a time. We have mapped and measured the most subtle accelerations of cosmic expansion.
In April 2024 the Dark Energy Spectroscopic Instrument (DESI) collaboration made headlines with a stunning announcement. Data from the first year of a galaxy survey that captured precise measurements of more than 13 million galaxies revealed slight but significant evidence that dark energy may be weakening with time. That is, the mysterious force or substance that is causing the expansion of the universe to accelerate might be fading away.
This new result adds to the growing list of problems faced by the leading model of cosmology, called LCDM for “lambda cold dark matter,” which hypothesizes that around 95 percent of all the stuff in the cosmos is either dark energy or dark matter. For years cosmologists have struggled with the so-called Hubble tension, a discrepancy between measurements of the present-day expansion rate based on the nearby universe compared with extrapolations taken from the ancient, distant cosmos.
To read more, click here.