Is our measurement system just a human invention or reality?

Music · Published 18 October 2026 Swipe more like this →

In short: We treat meters and seconds as fundamental truths of the universe. But what if they are merely convenient human constructs? In theoretical physics, you can actually eliminate almost every base unit by redefining how we view universal constants.

The International System of Units (SI) currently relies on seven base units: the kilogram, metre, second, ampere, kelvin, mole, and candela. These are defined as a subset of physical quantities where no quantity can be expressed in terms of the others. However, many of these relationships are governed by fundamental constants. For example, because time and distance are linked by the speed of light (c), it is mathematically possible to eliminate either the metre or the second from our system by setting c to a fixed dimensionless number.

This leads to an ontological debate in physics: do these base quantities actually exist independently, or are they just labels? Some physicists argue that only dimensionless values have true physical meaning and that all dimensional units are human constructs. For instance, temperature can be expressed as energy per particle per degree of freedom—a value that could ultimately be reduced to mass, length, and time. Similarly, the mole is often viewed as a technical scaling constant (the Avogadro constant) rather than a fundamental dimension.

In theoretical physics, researchers often use 'natural units' where constants like c and ħ are set to 1. This allows every physical quantity to be expressed as a dimensionless number. By systematically applying this logic to constants like the vacuum permittivity or the Boltzmann constant, one could theoretically reduce the entire universe down to a single base dimension. The choice of which units to keep is often arbitrary, varying by field, and reflects our preference for practical convenience over absolute ontological truth.

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