quantum gravity - What is the smallest existing thing in theory and law?

What is the smallest existing thing in theory and law?

Answer

"What is the smallest existing thing in theory and law?"

The Merriam Webster Dictionary defines a "thing" as:

1. 
   

   : an object or entity not precisely designated or capable of being designated

   
   


2. 
   

   a: an inanimate object distinguished from a living being b: a separate and distinct individual quality, fact, idea, or usually entity c: the concrete entity as distinguished from

   
   



3. ...

A Photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles). Mass: 0 < 1×10−18 eV/c^2.

The photon has zero rest mass and always moves at the speed of light within a vacuum. Since the Photon is a Point Particle and has a size of zero you might say it's not a thing, nothing; that leaves us with:

The smallest real thing is the Neutrino. Mass: ≤ 0.120 eV/c^2.

The smallest theoretical thing is the Planck Particle. Radius: 5.72947×10−35 m, Mass: 3.85763×10−8 kg.