A black hole has a boundary that nothing can cross from the inside out. This boundary is called the horizon. It turns out that the horizon behaves like a hot object: it has a temperature and a measure of disorder that physicists call entropy. When the horizon heats up, it gives off heat, and from this simple rule you can derive the law of universal gravitation.
In a new paper, a scientist changed the entropy formula and looked at how this affects gravity. It turned out that any change in entropy alters the strength of attraction. It is as if the scale of a thermometer set the stiffness of a spring. He then devised a new entropy in which the horizon has a minimum area, below which it cannot shrink. Thanks to this, at the very beginning of the Universe there was no infinite density, but rather a rapid yet smooth expansion.
The minimum horizon area A₀ plays a role analogous to the ground-state energy of a quantum harmonic oscillator: even in an "empty" horizon there remains an irreducible quantum activity. In the model, allowed areas are quantized as A = nA₀, where n ≥ 2, meaning the n=1 state is forbidden due to logarithmic divergence.
The idea that gravity arises from horizon thermodynamics echoes Liu Cixin's novel The Three-Body Problem, where an alien civilization manipulates fundamental laws through curled-up dimensions. Here, horizon entropy acts as code that rewrites gravity.