Webb Telescope Confirms: Universe is Expanding

WASHINGTON, Dec 9 (Reuters) - Fresh corroboration of the perplexing observation that the universe is expanding more rapidly than expected has scientists pondering the cause - perhaps some unknown factor involving the mysterious cosmic components dark energy and dark matter.

Two years of data from NASA's James Webb Space Telescope have now validated the Hubble Space Telescope's earlier finding that the rate of the universe's expansion is faster - by about 8% - than would be expected based on what astrophysicists know of the initial conditions in the cosmos and its evolution over billions of years. The discrepancy is called the Hubble Tension.  READ MORE...

Understanding our Universe

A new study amplifies the Hubble tension, a discrepancy in cosmic expansion rate measurements, by providing the most accurate calibration of Cepheid stars for distance measurements. This discrepancy calls into question fundamental concepts in physics and has implications for understanding dark energy, the time-space continuum, and gravity.

When it comes to measuring how fast the Universe is expanding, the result depends on which side of the Universe you start from. An EPFL study has calibrated the best cosmic yardsticks to unprecedented accuracy, shedding new light on the Hubble tension.

The Hubble tension, a discrepancy in the cosmic expansion rate (H0) between early Universe and late Universe measurement methods, has puzzled astrophysicists and cosmologists.

 A study by the Stellar Standard Candles and Distances research group at EPFL’s Institute of Physics has achieved the most accurate calibration of Cepheid stars for distance measurements, amplifying the Hubble tension. The discrepancy calls into question the basic concepts of physics and has implications for the nature of dark energy, the time-space continuum, and gravity.


The Universe is expanding – but how fast exactly? The answer appears to depend on whether you estimate the cosmic expansion rate – referred to as the Hubble’s constant, or H0 – based on the echo of the Big Bang (the cosmic microwave background, or CMB) or you measure H0 directly based on today’s stars and galaxies. This problem, known as the Hubble tension, has puzzled astrophysicists and cosmologists around the world.


A study carried out by the Stellar Standard Candles and Distances research group, lead by Richard Anderson at EPFL’s Institute of Physics, adds a new piece to the puzzle. 

Their research, published today (April 4) in the journal Astronomy & Astrophysics, achieved the most accurate calibration of Cepheid stars – a type of variable star whose luminosity fluctuates over a defined period – for distance measurements to date based on data collected by the European Space Agency’s (ESA’s) Gaia mission. This new calibration further amplifies the Hubble tension.  READ MORE...