Is Space Sticky? New Study Challenges Standard Dark Energy Theory

In the standard Lambda-CDM model, dark energy – the mysterious force behind the universe's accelerating expansion – is treated as a constant background. But new data from the Dark Energy Spectroscopic Instrument (DESI) hint at a mismatch with this model: galaxies appear to be receding slightly faster than predicted. A recent preprint suggests that treating space as a viscous ‘sticky fluid' might reconcile the difference. This idea implies the cosmos may be ‘stickier' than thought, with a ghostly viscosity slowing its growth.

Space as a viscous fluid

According to Khan's paper, the vacuum might have a “bulk viscosity”, meaning a subtle drag on cosmic expansion. For example, viscosity is like the difference between pouring water and honey; space would be slightly sticky as it expands. He imagines space as an elastic medium: tiny longitudinal “phonon” vibrations (sound waves in the vacuum) generate this viscosity.

This ghostly resistance would slow expansion, and the model reportedly matches DESI data: the observed cosmic slowdown aligns with these predictions. It may resolve a noted tension: DESI found galaxies receding slightly faster than Lambda-CDM predicts.

Implications and outlook

As Khan's preprint is unreferenced and unpublished, it is advised to be treated with care. Sutter himself advises, “We should approach cautiously—this is only a hypothesis.” This hypothesis, if correct, would be ‘a paradigm shift in our understanding of the nature of the vacuum of space.' Future work by DESI and Euclid telescopes is needed to verify if such ‘spectres' are in fact the correct description of the expansion of our cosmos. For the time being, the ‘Lambda CDM model' is in its usual place.