In a universe filled with radiation, this density can be thought of as a kind of pressure on all of space, which depends on the universe's temperature and its number of spatial dimensions. The scientists propose that space is 3D because of a thermodynamic quantity called the Helmholtz free energy density.

This is the first time that the number 'three' of the space dimensions arises as the optimization of a physical quantity.' 'The greatest significance of our work is that we present a deduction based on a physical model of the universe dimensionality with a suitable and reasonable scenario of space-time. 'A number of researchers in the fields of science and philosophy have addressed the problem of the (3+1)-dimensional nature of space-time by justifying the suitable choice of its dimensionality in order to maintain life, stability and complexity,' coauthor Julian Gonzalez-Ayala, at the National Polytechnic Institute in Mexico and the University of Salamanca in Spain, told.

In a new paper published in EPL, researchers have proposed that the second law of thermodynamics may also explain why space is 3D.

3 dimensional art