Rut roh! Dark energy may not exist

A new analysis of existing cosmological data led researchers to hypothesize that because the cosmos is lumpy, not smooth, there is no need to posit the existence of dark energy. Dark energy has been hypothesized to exist to explain an apparent anti-gravity source that is causing the observed rate of expansion of the universe. The logic here is mind-blowingly simple: 

Ouch, I need an aspirin

In places with gravity, such as the space in and near galaxies time runs about 35% slower than in places of empty space with little gravity from nearby matter. The universe has intergalactic voids where time runs faster. Taking that simple understanding and attendant logic into account, existing cosmological data can explain the currently observed rate of expansion of the universe without invoking dark energy. Science Daily:

Now a team of physicists and astronomers at the University of Canterbury in Christchurch, New Zealand are challenging the status quo, using improved analysis of supernovae light curves to show that the Universe is expanding in a more varied, "lumpier" way.

The new evidence supports the "timescape" model of cosmic expansion, which doesn't have a need for dark energy because the differences in stretching light aren't the result of an accelerating Universe but instead a consequence of how we calibrate time and distance.

It takes into account that gravity slows time, so an ideal clock in empty space ticks faster than inside a galaxy.

The model suggests that a clock in the Milky Way would be about 35 per cent slower than the same one at an average position in large cosmic voids, meaning billions more years would have passed in voids. This would in turn allow more expansion of space, making it seem like the expansion is getting faster when such vast empty voids grow to dominate the Universe.

Professor David Wiltshire, who led the study, said: "Our findings show that we do not need dark energy to explain why the Universe appears to expand at an accelerating rate.

"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."  

Dark energy is commonly thought to be a weak anti-gravity force which acts independently of matter and makes up around two thirds of the mass-energy density of the Universe.

The data and analysis this research is based on came from existing cosmological data from 1,535 carefully observed supernovae. It will take several years of careful observations of about 1,000 more supernovae to confirm or refute this new explanation. How likely is this hypothesis going to be confirmed? If Perplexity is a reliable source, this seems to be the real deal and it probably will be confirmed:

In summary, the new research is persuasive in that it offers a coherent alternative to the dark energy paradigm, supported by observational data and addressing long-standing cosmological puzzles. However, its acceptance hinges on future observations and the scientific community's ability to reconcile these findings with existing data. The research represents a significant challenge to the standard model, but its ultimate persuasiveness will depend on the robustness of its predictions and the consistency of future observations with its framework.

Milky Way galaxy (center) near the 

edge of a local void in space

 

Our local void is about 

2 billion light years wide

(aw cute, it's sort of heart-shaped,

from this angle)

By Germaine: A local source of intense heat & funny-smelling gas