Cosmic Ruler: Inflection Point Instead of Peak express
There's no tool to measure distances to faraway galaxies, but nature left a clue: after the Big Bang, sound waves created rhythmic clumps of matter. Today, this is noticeable as a slight preference for galaxies to be at a certain distance from each other — a built-in ruler. Over cosmic time, the pattern blurs, like a sand dune in the wind: the sharp peak on the distance graph becomes a gentle slope, but its steepest part barely moves. This inflection point — the linear point — more reliably preserves the imprint of the early universe.
Data from the DESI project, mapping millions of galaxies, confirmed its advantages. After reconstruction, which partially cleans the signal from late-time distortions, measurement precision improved by 15–60%. A small correction for the galaxy sample composition, accounting for dark matter and gravity, yielded perfect agreement with traditional measurements. Thus, the linear point becomes a new tool for hunting dark energy and understanding the future of the universe's expansion.
The theoretical idea has been around since the 2010s, but only DESI's unprecedented maps allowed it to be used with sub-percent precision — and it turned out that the inflection point is more informative than the blurred peak.