How is the “Plank Length” the absolute limit of how small something can be?
In: Physics
It’s not. That is a commo pop science description of the Planck Length but it isn’t the real picture. The Planck Length is the base unit of length in the Planck Unit system, this is a system of units (like metric or imperial) defined so that certain constants like the speed of light are equal to 1. This makes doing mathematics easier as you can mostly ignore these constants.
The reason the Planck Length is often referred to as the shortest length comes from a misunderstanding about quantum mechanics. At scales below the Planck Length our modern understanding of physics breaks down, we don’t yet have a good understanding of how gravity interacts with quantum mechanics and at these scales both gravity and quantum mechanics will be important. This means to accurately describe physics at scales smaller than the Planck length we need a theory of quantum gravity, which we don’t currently have.
Basically the Planck length is around where our understanding of physics ends, but it isn’t a sharp cutoff just a gradual loss of accuracy and it doesn’t imply the Planck length is important physically for how small things can be. It is just a limitation of our theories.
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