The Universe's Physical Constants May Be Perfectly Tuned to Allow Life to Exist

A Universe Built Just Right for Life

Picture a universe nearly identical to our own — stars burning brightly, planets orbiting, water present in abundance — but where nothing can live. Not because the chemistry is wrong, but because the liquids are too thick. Imagine a universe where stars still shine, planets still form, and water exists, but liquids are so thick that living cells can barely function — and even with the chemical ingredients for life, the conditions make living organisms impossible. That unsettling scenario is at the heart of a remarkable new discovery from physicists at Queen Mary University of London.

Scientists have uncovered a remarkable connection between the fundamental laws of physics and the ability of life to exist, finding that even relatively small changes to some of the universe's most basic physical constants could dramatically alter how liquids flow, potentially preventing essential biological processes from taking place. The research, led by physicist Kostya Trachenko, adds a compelling new dimension to one of science's oldest and deepest questions: Why does the universe seem so perfectly suited for life?

The Hidden Role of Viscosity

Life depends on movement at microscopic scales. Nutrients must travel through cells, proteins need to fold correctly, and molecules constantly diffuse through watery environments — all of which relies on viscosity, the property that determines how easily a liquid flows. It turns out that this seemingly mundane physical property is directly tied to the universe's most fundamental constants.

An important clue emerged in 2020, when Trachenko and his colleagues demonstrated that fundamental physical constants place a lower limit on the viscosity of liquids. The discovery, detailed in a study published in *Science Advances*, came from Trachenko's theoretical analysis, which identified an additional constraint on the values of fundamental physical constants: they must permit liquids to move in ways that support life within and between cells. In other words, the universe's deep physical rules don't just allow atoms and stars to exist — they appear to keep the fluids inside our cells flowing at exactly the right speed.

Trachenko noted that a shift of only a few percent in constants like the Planck constant or electron charge would alter the viscosity of blood beyond functional limits, making cellular life impossible across the universe. That's a razor-thin margin — and yet, here we are.

More Than Stars and Chemistry

Scientists have long known that the universe's constants must fall within certain ranges just to produce stars and complex chemistry. Long before the first living cells appeared, stars were producing elements such as carbon and oxygen that would eventually become essential components of living organisms, and physicists have long investigated whether the constants governing these nuclear processes must fall within certain ranges for complex matter to exist — but the ability to create life's chemical ingredients does not necessarily guarantee that life can function.

Trachenko's analysis further indicated that physical properties governing liquid behavior could change independent of those required for nuclear reactions, meaning a variant universe could still produce elements essential for life but manifest liquids with such viscosity that cellular phenomena could not function effectively. This is what makes the finding so striking: even a universe that "does everything right" in terms of building blocks could still be completely barren.

A Mystery That Cuts to the Core of Existence

Surprisingly, these life-friendly conditions existed billions of years before living cells appeared, raising intriguing questions about why the laws of physics seem so well suited to life. The researchers even suggest that multiple stages of tuning may have occurred, with Trachenko comparing the possibility to biological evolution, where traits emerge independently over time — an idea that remains speculative, but raises the possibility that nature may favor stable physical structures in ways scientists do not yet fully understand.

Trachenko's work underscores the vital connection between fundamental physics and biological systems on Earth, as well as the potential for life beyond our planet — and the sensitivity of fluid viscosity to tiny shifts in physical constants could have far-reaching implications for astrophysics and the study of extraterrestrial life. As scientists continue probing the deep structure of the cosmos, this research suggests that the question of why life exists may be inseparable from the question of why the universe's most basic rules are what they are.