Question: how big is the biggest particle.

Deepak Kar answered on 18 Mar 2014:

Thats a hard question!

We dont really see the particles directly. In fact we cant even calculate their size in the conventional sense, like you can measure for a tennis ball. There is a law in physics (called uncertainty principle), which states that for tiny particles, you can measure the position and speed simultaneously with perfect precision. So when cant even measure their position, how can you measure the size?

So we use mass (or the energy, they are equivalent as per E=mc^2) to judge the particles. If we are talking only about the elementary particles, then top quark has the heaviest mass, but it is about 3 times 10^-31 kg 😀