Cosmologists are quietly confronting a possibility that would have sounded absurd a generation ago: the standard picture of a smooth, empty vacuum may be wrong unless space itself behaves like a sticky, shape-shifting fluid. The crisis is being driven by increasingly precise measurements of how fast the universe is expanding, which refuse to line up no matter how carefully researchers recheck the data. I see a pattern emerging in that tension, one that points toward a universe whose very fabric resists stretching and flowing in ways our current equations do not capture.
The crisis of a “broken” universe model
For more than two decades, cosmologists have relied on a framework in which ordinary matter, dark matter and dark energy evolve in a smooth, predictable way from the Big Bang to today. That picture is now under strain because independent measurements of the cosmic expansion rate disagree so sharply that lead authors describe the situation as a crisis for the field. One team has argued that our model cannot simultaneously match the early universe and the local one, no matter how they tweak the parameters.
The latest blow came when final observations from the Atacama Cosmology Telescope, or ACT, ruled out roughly 30 different versions of the universe’s evolution that had been considered viable. Those data suggest that space is not as uniform and well behaved as the standard equations assume, and that the expansion history is more complicated than a simple balance between matter and a smooth dark energy field. When I look across these results, the common thread is that the vacuum itself seems to be doing something unexpected, as if the medium of space has hidden properties that only show up at the highest precision.
Hubble tension and the “Laminar Constant”
The most visible symptom of this breakdown is the so‑called Hubble tension, the mismatch between the expansion rate inferred from the early universe and the rate measured from nearby galaxies. Over the past decade, that discrepancy has widened as teams have refined their techniques, turning what was once a mild annoyance into a full‑blown challenge to basic physics. One group studying the expansion rate has been blunt that DESI and related surveys now see the universe expanding too fast for the standard model to explain.
In response, some researchers have tried to codify the observed expansion into new constants that explicitly acknowledge the messy, possibly viscous behavior of space. On December 26, 2025, the Tomilson-Hawkin Foundation, or THF, formally logged the 71.4 km/s/Mpc Attractor as the “Laminar Constant,” a value meant to capture a preferred large‑scale flow pattern in the cosmos. The very choice of the word “laminar,” borrowed from fluid dynamics, hints at a shift in mindset: instead of treating the universe as a static stage, some teams are beginning to describe it as a medium whose internal friction and flow patterns might be just as important as its overall expansion rate.
Dark components and a sticky cosmic budget
Any attempt to fix this broken picture has to grapple with the fact that the vast majority of the universe is already invisible and poorly understood. The prevailing model of cosmology reveals that approximately 95% of the cosmos is made of dark matter and dark energy, entities that have never been detected directly in a laboratory. If those components are not simple, non‑interacting substances but instead form a complex fluid with its own internal stickiness, then the expansion history could easily deviate from the neat curves drawn in textbooks. I find it telling that the biggest anomalies all involve how this dark sector behaves over time, not the familiar atoms that make up stars and planets.
Some theorists have gone further and proposed that dark matter and dark energy are not separate ingredients at all, but different manifestations of a single exotic medium. One line of work suggests that a strange dark fluid could unify these phenomena if it has the right pressure and density properties. In that view, the universe’s missing mass and its runaway expansion are two sides of the same coin, both emerging from the way this fluid resists compression and stretching. A sticky cosmic medium would naturally clump on some scales while flowing freely on others, potentially explaining why galaxies form the way they do even as the large‑scale expansion accelerates.
From oobleck to negative mass: reimagining the vacuum
The idea that space behaves like a fluid is not just a metaphor. A recent study has proposed that the vacuum may be a non‑Newtonian medium, similar to the cornstarch‑and‑water mixture known as oobleck that stiffens when struck and flows when handled gently. In this picture, the vacuum’s response to motion and gravity depends on how it is stirred, which could help resolve a decades‑old mystery involving the trajectories of two NASA probes that did not match simple gravitational predictions. By treating space itself as a non‑Newtonian fluid, the study opens the door to a universe where viscosity and shear are as fundamental as curvature.
Other theorists have explored even stranger territory by imagining a “negative‑mass” dark fluid that continuously pops into existence. One model shows that when more and more negative masses are created, the resulting negative mass fluid does not blow the universe apart but instead settles into a stable configuration that can mimic dark energy. In that scenario, the vacuum is not empty at all, it is a seething medium whose unusual inertia drives cosmic acceleration. I see these proposals as part of a broader trend: rather than adding new particles to patch the data, researchers are rewriting what it means for space to have “nothing” in it.
Cosmological viscosity and the specter of a Big Rip
If space is a fluid, then it can have viscosity, a measure of how much it resists being deformed. In cosmology, that concept appears as what some researchers call Cosmological viscosity, essentially the stickiness of the universe itself. Unlike the thickness of ketchup, which measures resistance to flow, this cosmic viscosity describes how strongly the medium of space resists expansion or contraction. If that resistance changes over time, it could alter the fate of the universe, slowing the expansion in some eras and turbocharging it in others.
One influential model has focused on the equation of state of dark energy, the ratio between its pressure and density, and how that ratio behaves in a viscous cosmic fluid. Work presented in Jun highlighted that if this ratio dips below a critical threshold, the universe could end in a “Big Rip,” where galaxies, stars and even atoms are torn apart by runaway expansion. In a sticky‑space picture, that catastrophic outcome is not just a curiosity, it is a direct consequence of how the vacuum’s internal friction evolves. The same viscosity that might help reconcile today’s data could, in the far future, decide whether the cosmos coasts gently or rips itself to shreds.
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