What is the smallest thing in the world?

The concept of the "smallest thing in the world" depends on what you mean by "thing." Here's a breakdown:

  • Fundamental Particles: At the most fundamental level currently understood by physics, the smallest known constituents of matter are fundamental particles. These include quarks and leptons (like electrons). These particles are considered point-like, meaning they have no measurable size or internal structure.

  • Quarks and Leptons: These particles, such as electrons, are not made up of anything smaller (as far as we know). They are considered truly elementary.

  • Planck Length: There's also the Planck length, which is the smallest unit of length that has any physical meaning in our current understanding of physics. It's about 1.6 x 10^-35 meters. At scales smaller than this, our current physical laws are thought to break down. This length is a theoretical limit to how small we can meaningfully measure distances.