New study blows dark energy theory to bits, says universe expansion is lumpy

Dark energy is one of the greatest mysteries of the universe. This mysterious force is thought to be accelerating the expansion of the cosmos. But a new study challenges this long-held belief.

A team of physicists and astronomers at the University of Canterbury in New Zealand have proposed a radical new idea. This model suggests that the universe isn’t expanding uniformly, but rather in a more “lumpy” fashion.

“Our findings show that we do not need dark energy to explain why the Universe appears to expand at an accelerating rate,” said Professor David Wiltshire, the lead author.

“Dark energy is a misidentification of variations in the kinetic energy of expansion, which is not uniform in a Universe as lumpy as the one we actually live in,” Wiltshire added.

Timescape model

The team’s refined analysis of supernovae light curves revealed a lumpy expansion of the universe.

The researchers explored the “timescape model.” This model challenges the standard cosmological model by suggesting an alternative explanation for the universe’s accelerated expansion – one that doesn’t rely on dark energy.

According to the timescape model, gravity slows down time. This means that “clocks” in the vast, empty voids of the universe tick faster than those in dense regions like galaxies.

As a result, these voids experience more time, allowing for more expansion. This can make it appear as though the universe is accelerating its expansion, even without the need for dark energy.

According to the model, the passage of time is significantly slower within the Milky Way, approximately 35 percent slower than in the vast, empty voids of the universe.

Scientists originally concluded the universe’s expansion is accelerating based on supernova observations. However, recent findings challenge this conclusion, indicating that the current expansion rate might not be as rapid as previously thought.

More observations required

Recent observations, such as the Cosmic Microwave Background (CMB) and data from the Dark Energy Spectroscopic Instrument (DESI), challenge the traditional understanding of the universe’s expansion.

These findings highlight discrepancies with the standard cosmological model, particularly the Hubble tension and the behavior of dark energy.

These inconsistencies suggest that the simplified Friedmann equation assumes a uniform expansion.

However, the actual universe is far more complex, with galaxies organized into a cosmic web of filaments and clusters, interspersed with vast empty voids.

“We now have so much data that in the 21st century we can finally answer the question – how and why does a simple average expansion law emerge from complexity?” said Wiltshire.

“A simple expansion law consistent with Einstein’s general relativity does not have to obey Friedmann’s equation,” he added in the press release.

While the timescape model offers a compelling alternative, more research is needed to confirm its validity. The European Space Agency’s Euclid satellite, launched in 2023, will play a crucial role in testing this theory.

The Euclid satellite can potentially distinguish between the traditional Friedmann equation and the timescape model. However, this requires a significant amount of high-quality supernova data, at least 1,000 observations.

Leveraging the extensive Pantheon+ catalog of 1,535 supernovae, the researchers found strong support for the timescape model. This model could potentially resolve the Hubble tension and other cosmic expansion anomalies.

Additional observations from the Euclid and Nancy Grace Roman Space Telescopes are crucial to further solidify the timescape model.

The findings were published in the journal Monthly Notices of the Royal Astronomical Society Letters.