I understand that composite particles with integer spin form a boson. For example a helium nucleus is a boson because it has 2 protons and 2 neutrons.

If all of the components on their own are fermions, which mean they can not occupy the same space, how can combining them allow them to now occupy the same space?

I guess my question is: Is there an "intuitive" explanation for this behavior, or is the answer just the integer spin always equals boson?


The Pauli exclusion principle applies to the constituent fermions of the composite bosons. For example, many atoms of helium can be in the same lowest energy state forming a superfluid. However, they cannot be squeezed to a zero volume, because the Pauli exclusion principle holds for protons and neutrons, as well as for their constituent quarks.

  • $\begingroup$ Ok, so only elementary particles that are bosons do not follow the Pauli exclusion formula? $\endgroup$ – jminardi Sep 24 '19 at 0:12
  • 1
    $\begingroup$ @jminardi Correct, elementary bosons (e.g. photons) do not follow the Pauli exclusion principle. $\endgroup$ – safesphere Sep 24 '19 at 2:53

Not the answer you're looking for? Browse other questions tagged or ask your own question.