Cosmic Clocks Diverge: A New Mystery of the Universe's Expansion ⚡ экспресс
The Hubble constant (the expansion rate of the Universe) remains a subject of debate: different methods yield incompatible values. The study re-analyzes the "distance ladder" based solely on Cepheids and their brightness, with improved accounting for data selection and galaxy motions. It obtains an estimate of H0 = 71.1 ± 1.4 km/s/Mpc, which is lower than the recent SH0ES value and deepens the discrepancy with the cosmic microwave background. This shows that even part of the ladder data can challenge the standard cosmological model, if "cosmic currents" are properly accounted for.
Measuring the expansion of the Universe is like checking the time on two perfect clocks: one set by the ancient light of the cosmic microwave background, the other by stars and supernovae. And the more precisely we compare them, the more their readings diverge. Now, a new 'clock' using only pulsating Cepheid stars has added a third, even more unexpected result.
Astronomers carefully accounted for the motion of galaxies relative to each other and obtained a Hubble constant of 71.1 (km/s)/Mpc. This is lower than the previous standard (73.2 from Adam Riess), but the discrepancy with the 'relic radiation' clock has grown to a level where chance is almost ruled out (less than 0.5%). Contrary to hopes, cleaning up the mechanism did not synchronize the clocks but only highlighted the fault.
In 1929, Edwin Hubble using the same Cepheids calculated 500 (km/s)/Mpc — it turned out he confused two types of these stars. We no longer confuse them, but the divergence hints that in the very mechanism of the cosmic clocks — the standard model — there may be some missing gears.
🎯 Edwin Hubble's first measurement in 1929 gave about 500 km/s per megaparsec — seven times larger than today's, because he didn't know about the two types of Cepheids.