Force

Force particle

Mass

Strong

Gluon

0

Electromagnetic

Photon

0

Weak

Weak gauge bosons

86, 97

Gravity

Graviton

0

Table 1.2 The four forces of nature, together with their associated force particles and their masses in multiples of the proton mass. (The weak force particles come in varieties with the two possible masses listed. Theoretical studies show that the graviton should be massless.)