Kostya Trachenko was sipping tea in London when he began wondering: what if the liquid in your cup suddenly flowed like tar? It sounds like a dream, but for life in our universe, it’s a line we never cross—thanks to invisible rules written into the fabric of reality. At Queen Mary University of London, Trachenko uncovered a surprising truth: the same numbers that govern atoms and stars also ensure liquids can flow freely enough for life to exist. His discovery, published in Science Advances, reveals that even tiny shifts in the universe’s fundamental constants could make fluids too thick for cells to function—effectively shutting down life before it could begin.
These constants—unchanging numbers like the electron’s mass and the Planck constant—are the silent architects of reality. They shape how atoms bond, how stars burn, and how liquids pour. In 2020, Trachenko and his team found that these constants set a lower limit on how freely any liquid can flow. Now, they’ve gone further: those same limits are essential for biology. Inside every living cell, molecules must move. Nutrients travel, waste is removed, and chemical reactions unfold—all in a liquid environment. A key player is diffusion, the natural spreading of particles through fluid. If liquids were even slightly more viscous, this delicate dance would slow to a crawl.
Water, blood, and cellular fluids all depend on just the right flow. Trachenko’s models show that if the Planck constant or the electron’s charge changed by just a few percent, viscosity would shift enough to disrupt life. Blood might thicken like syrup, or become so thin it couldn’t carry oxygen properly. "If water was as viscous as tar, life would not exist in its current form or not exist at all," Trachenko says. And it’s not just water—any liquid-based life, even on distant planets, would face the same constraints.
What’s astonishing is that these same constants also control how stars forge carbon, oxygen, and other elements essential for life. The universe appears fine-tuned in multiple ways at once: not just to make the ingredients of life, but to allow them to move, mix, and react. While we can’t test alternate universes, the theory suggests life may only be possible within a narrow window of physical laws. This doesn’t explain why the constants have these values—but it shows how deeply life is woven into the physics of the cosmos. As scientists keep probing these mysteries, one thing becomes clearer: we are not just in the universe. We are of it—flowing, breathing, and existing because the rules allow it.