An ice cube in a glass of water doesn't just float: it gets pushed. Water molecules bombard it from all sides, and this bombardment gives rise to a force you can measure. In physics, there's a similar force, but it acts not on ice but on anything with mass, and it arises not from molecular jostling but from information. It's called entropic force. Around a black hole, you can imagine an invisible sphere: its horizon. On this sphere, like on a screen, information about everything that has fallen inside is 'recorded.' When something approaches the horizon, the information on it rearranges, and this rearrangement pushes the object outward. That's how entropic force is born.
But what happens when the very fabric of space stops being smooth? At scales comparable to the Planck length, which is billions upon billions of times smaller than an atomic nucleus, space and time may become grainy. There, you can no longer say precisely where a particle is and how fast it's moving. The usual Heisenberg uncertainty principle breaks down, and its extended versions with mysterious names like GUP or EUP take the stage. They add tiny corrections to the familiar formulas, depending on as-yet-unknown parameters of quantum gravity. The authors of the new study took these extended principles and recalculated the entropic force using them.
It turned out that the force changes depending on which uncertainty model you choose. In one case, the correction depends on the particle's energy; in another, on the size of the region where the interaction occurs. And in the EUP model, the force is directly linked to how many Planck 'squares' fit on the surface in question. This is similar to how gas pressure changes with the number of molecules: the more cells on the horizon, the more noticeable the quantum gravity effect. This approach doesn't give a definitive answer as to which theory is correct, but it builds a bridge between abstract equations and what could be measured in the future.
Someday, it might be possible to detect deviations in particle motion near black holes or in the early universe. Then the entropic force, corrected by quantum uncertainty, will cease to be a mind game and become a key to understanding what space is truly made of.
as written by the authors arXiv:2605.07992
We consider quantum gravity corrections to the maximum entropic force that arise from several gravitational uncertainty principles. These include the Generalized Uncertainty Principle (GUP), the Extended Uncertainty Principle (EUP), the Generalized Extended Uncertainty Principle (GEUP), and the Linear-Quadratic GUP (LQGUP). We find that the modified entropic force depends on the dimensionless parameters of the uncertainty principles and, thus, on the underlying quantum gravity theory. Furthermore, the entropic force, which is quantum gravity corrected in the framework of the extended uncertainty principles, also depends on the number of Planck areas that made the ``EUP area".
You can feel entropic force yourself: when you stretch a rubber band, it heats up, and when you compress it, it cools down. This happens because the molecules inside the band rearrange, changing their entropy, and this rearrangement creates mechanical stress.
In Peter Watts's novel Blindsight, alien beings use quantum effects to manipulate information on event horizons, echoing the idea of controlling entropic forces.