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What is the smallest possible thing?

This a more complicated question than it appears at first glance, because it depends upon the criterion used to define "small", that is, what is the instrument of measurement. From a theoretical view, there is a quantity called the "Planck length" which is the only quantity of "length" that is a combination of the fundamental constants of nature. Its value is about 1.6 x 10^-35 meters. Its derivation is a bit involved, so I will not attempt to go into more detail here. You can refer to:

for more details. The complication arises because you could counter with -- How about 1/2 a Planck length?

Vince Calder


The smallest possible thing in physics, well in many ways we are still search for what made and was the origin of the big bang,....this is what FermiLab and Cern's LHC is about........we are looking for experimental proof of the Higgs Boson. Hope this helps and gives you some ideas to read about... this will help answering the smallest entity in physics.

Prof. Harry Przekop, Physicist

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