The James Webb Telescope Confirms Humans’ Misunderstanding of the Universe

Astronomers have used the James Webb and Hubble Space Telescopes to confirm one of the most troubling puzzles in all of physics—that the universe appears to be expanding at startlingly different rates depending on where scientists look.

The problem, known as the Hubble tension, has the potential to change or even completely upend cosmology. In 2019, measurements from the Hubble Space Telescope confirmed that the mystery was real, and in 2023, even more precise measurements from the James Webb Space Telescope (JWST) confirmed the discrepancy.

The checks carried out by both telescopes forever eliminated the possibility of any measurement error. The study, published in Astrophysical Journal Letters, suggests there may be something seriously wrong with human understanding of the universe.

“Now that measurement errors have been eliminated, there remains a real and exciting possibility that we have misunderstood the universe,” said study lead author Adam Riess.

Recall that Adam Riess, Saul Perlmutter and Brian P. Schmidt received the 2011 Nobel Prize in Physics for their 1998 discovery of dark energy, the mysterious force behind the accelerating expansion of the Universe.

Currently, there are two “gold standard” methods for determining the Hubble constant, a value that describes the rate of expansion of the Universe. The first involves studying tiny fluctuations in the cosmic microwave background (CMB), an ancient relic of the universe’s first radiation, created just 380,000 years after the Big Bang.

Between 2009 and 2013, astronomers mapped this microwave haze using the European Space Agency’s Planck satellite to determine the Hubble constant to be approximately 46,200 miles per hour per million light years, or approximately 67 kilometers per second per megaparsec (km/ s/PDK).

The second method uses pulsating stars called Cepheid variables. Cepheid stars die, and their outer layers of helium gas grow and contract as the star’s radiation is absorbed and released, causing them to periodically flicker like pilot lights in the distance. As Cepheids become brighter, they pulsate more slowly, giving astronomers a way to measure their absolute brightness. By comparing this brightness with their observed brightness, astronomers can arrange Cepheids into a “cosmic distance ladder” to peer even deeper into the universe’s past. Using this ladder, astronomers can determine the exact number for its expansion based on how much the Cepheid light is stretched or redshifted.

But this is where the mystery begins. According to measurements of the Cepheid variable by Riess and his colleagues, the expansion rate of the Universe is about 74 km/s/Pac: an incredibly high value compared to Planck’s measurements. Cosmology was thrown into uncharted territory.

“We wouldn’t call this a tension or a problem, but rather a crisis,” said Nobel Prize-winning astronomer David Gross.

Initially, some scientists believed that this discrepancy may be the result of a measurement error caused by Cepheids mixing with other stars in the Hubble aperture. But in 2023, researchers used the more precise JWST telescope to confirm that for the first few “rungs” of the cosmic ladder, their Hubble measurements were correct. However, the possibility of further travel into the past of the Universe remains.

To solve this problem, Riess and his colleagues built on their previous measurements by observing another 1,000 Cepheid stars in five host galaxies up to 130 million light-years from Earth. By comparing their data with Hubble’s, the astronomers confirmed their past measurements of the Hubble constant.

“We have now covered the full range of Hubble observations and can rule out measurement error as the cause of the Hubble intensity with a very high degree of confidence,” Riess said. “The combination of Webb and Hubble gives us the best of both worlds. We find that Hubble’s measurements remain reliable as we move further up the cosmic distance ladder.”