Recent observations have revealed flaws in our understanding of the universe, and a new study suggests that may be because the universe is more “sticky” than we assumed.
In a paper published on the arXiv preprint server but not peer-reviewed, Indian Institute of Technology researcher Muhammad Ghulam Khwaja Khan suggests that space may have a property called bulk viscosity.
Viscosity is a measure of how much a fluid resists flowing or changing shape, like the difference between pouring water and pouring honey. In this case, we are talking about the bulk viscosity of the vacuum itself, the ghostly resistance that occurs as space expands.
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constant problem
Traditionally, scientists have used simple models to explain the universe. In this model, known as Lambda CDM, dark energy (the mysterious force responsible for the accelerating expansion of the universe) is a stable, unchanging background known as the cosmological constant.
But data released last year from the Dark Energy Spectroscopy Instrument (DESI) aboard the Mayall Telescope at Kitt Peak National Observatory in Arizona suggested that something may be fundamentally wrong with our understanding of dark energy. New observations show a slight discrepancy between our Standard Model and the speed at which galaxies are actually observed moving away from us.
To explain this contradiction, Kahn proposed a model involving spatial “phonons”. In solid state physics, phonons are essentially collective vibrations of atoms within a crystal. However, Kahn applied this idea to the structure of the universe itself. He suggested that these longitudinal vibrations, acting as sound waves in the vacuum, could be responsible for the viscous effects that slow the expansion of the universe to an extent consistent with what we see in the sky.
This model provides resistance to the expansion of the universe by treating it as a viscous fluid. As space stretches, these spatial phonons move around, creating a pressure that counteracts the outward pressure. In fact, this study shows that this simple database model can fit DESI data very accurately and potentially solve some of the headaches caused by standard cosmological constants.
But we need to act carefully. This is just a guess. Viscous dark energy could lead to fundamental changes in the way we view the vacuum of space, and hard data from DESI is still being analyzed by the scientific community. It remains to be seen whether this viscosity is a fundamental property of nature or just a dull artifact of current measurements.
So where do we go from here? The next decade of data from missions such as the Euclid Space Telescope and continued monitoring by DESI will be the ultimate test. Further observations are needed to find out whether these ghostly vibrations really govern the universe, or if the universe is as smooth as we once believed.
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