Universe’s Expansion Defies Explanation: New Data Shatters Cosmological Models

New research confirms the Universe is expanding faster than theoretical models predict, intensifying the Hubble tension.

Using precise measurements of the Coma cluster, scientists recalibrated the cosmic distance ladder, suggesting flaws in existing cosmological models.

Expanding Universe: A Startling Discovery

The Universe appears to be expanding faster than expected — faster than theoretical models predict and beyond what our current understanding of physics can explain.

New measurements have confirmed earlier, highly debated results showing this unexpected rate of expansion. The gap between these findings and established models is known as the Hubble tension. Now, research published in Astrophysical Journal Letters offers even stronger evidence that the Universe is growing at a faster pace.

“The tension now turns into a crisis,” said Dan Scolnic, who led the research team.

Intensifying Cosmic Dilemma

Since Edwin Hubble’s 1929 discovery that the Universe is expanding, determining the precise rate of this expansion — called the Hubble constant — has been a cornerstone of cosmological research.

Scolnic, an associate professor of Physics at Duke University, explains it as trying to build the Universe’s growth chart: we know what size it had at the Big Bang, but how did it get to the size it is now? In his analogy, the Universe’s baby picture represents the distant Universe, the primordial seeds of galaxies. The Universe’s current headshot represents the local Universe, which contains the Milky Way and its neighbors. The standard model of cosmology is the growth curve connecting the two. The problem is: things don’t connect.This illustration shows the three basic steps astronomers use to calculate how fast the universe expands over time, a value called the Hubble constant. All the steps involve building a strong “cosmic distance ladder,” by starting with measuring accurate distances to nearby galaxies and then moving to galaxies farther and farther away. This “ladder” is a series of measurements of different kinds of astronomical objects with an intrinsic brightness that researchers can use to calculate distances. Credit: NASA, ESA and A. Feild (STScI)

The Broken Model of Cosmology

“This is saying, to some respect, that our model of cosmology might be broken,” said Scolnic.

Measuring the Universe requires a cosmic ladder, which is a succession of methods used to measure the distances to celestial objects, with each method, or “rung,” relying on the previous for calibration.

The ladder used by Scolnic was created by a separate team using data from the Dark Energy Spectroscopic Instrument (DESI), which is observing more than 100,000 galaxies every night from its vantage point at the Kitt Peak National Observatory.

Scolnic recognized that this ladder could be anchored closer to Earth with a more precise distance to the Coma Cluster, one of the galaxy clusters nearest to us.

Precise Measurements Challenge Established Theories

“The DESI collaboration did the really hard part, their ladder was missing the first rung,” said Scolnic. “I knew how to get it, and I knew that that would give us one of the most precise measurements of the Hubble constant we could get, so when their paper came out, I dropped absolutely everything and worked on this non-stop.”

To get a precise distance to the Coma cluster, Scolnic and his collaborators, with funding from the Templeton foundation, used the light curves from 12 Type Ia supernovae within the cluster. Just like candles lighting a dark path, Type Ia supernovae have a predictable luminosity that correlates to their distance, making them reliable objects for distance calculations.

The team arrived at a distance of about 320 million light-years, nearly in the center of the range of distances reported across 40 years of previous studies — a reassuring sign of its accuracy.

“This measurement isn’t biased by how we think the Hubble tension story will end,” said Scolnic. “This cluster is in our backyard, it has been measured long before anyone knew how important it was going to be.”

Using this high-precision measurement as a first rung, the team calibrated the rest of the cosmic distance ladder. They arrived at a value for the Hubble constant of 76.5 kilometers per second per megaparsec, which essentially means that the local Universe is expanding 76.5 kilometers per second faster every 3.26 million light-years.