Originally Posted by

**UKSmartypants**
Well in physics, measurements are important,and to measure anything at the Planck scale, you’d need a particle with sufficiently high energy to probe it. ..to get down to Planck lengths, you need a particle at the Planck energy: ~10^{19} GeV, or so. At such ultra-high energies,the momentum of the particle would be so large that the energy-momentum uncertainty would render that particle indistinguishable from a black hole. This is truly the scale at which our laws of physics break down.

At present, there is no way to predict what’s going to happen on distance scales that are smaller than about 10^{-35 }meters, nor on timescales that are smaller than about 10^{-43} seconds. These values are set by the fundamental constants that govern our Universe. In the context of General Relativity and quantum physics, we can go no farther than these limits without getting nonsense out of our equations in return for our troubles.

If we decide to go down to below about 10^{-35 }meters — the Planck distance scale — our conventional laws of physics would need many quantum corrections,or else would give nonsensical answers.. there are quantum corrections of order ~ħ that arise. There are corrections of all orders: ~ħ, ~ħ2, ~ħ3, and so on,and at Planck scale we cannot ignore the higher order corrections,as we do at larger length scales.

At the Planck distance scale, this implies the appearance of black holes and quantum-scale wormholes, which we cannot investigate.

But at these ultra-intense energy, the curvature of space is unknown. We cannot calculate anything meaningful.

If you put a particle in a box that’s the Planck length or smaller, the uncertainty in its position becomes greater than the size of the box.

The background curvature of space that we use to perform quantum calculations is unreliable, and the uncertainty relation ensures that our uncertainty is larger in magnitude than any prediction we can make. The physics that we know can no longer be applied,a la Ethan Siegel blog post.

That is why we limit space at Planck scale,to avoid a breakdown of known laws. Physicists put a fundamental minimum scale . Of course, a finite, minimum length scale would create its own set of problems. That would imply questioning the fundamentality of Lorentz invariance,and Einstein relativity.

May be we need some fundamental paradigm shifts to transcend Planck epoch.According to Brian Greene, there's a minimum possible length beyond which getting smaller is mathematically equivalent to getting larger. Anyhoo, I thought you were a fan of Loop Quantum Gravity, which make space itself discrete on the scale of the planck length.