Question

A particle with mass m 0 (a neutrino, possibly) carries momentum. How can this be in view of p = mv, in which we see that the momentum is directly proportional to the mass?

Answer 1

A neutrino can carry momentum without mass due to the principles of special relativity, where momentum for a massless particle is given by p = E/c, with E as energy and c as the speed of light.

Step-by-step explanation:

A particle such as a neutrino carrying momentum without having mass seems confusing when we consider the classical mechanics formula p = mv, where p represents momentum, m the mass, and v the velocity.

However, in the realm of special relativity and quantum mechanics, this concept is refined. For massless particles like neutrinos and photons, the equation E2 = (pc)2 + (mc2)2 becomes relevant.

If the mass (m) is zero, this simplifies to p = E/c. Hence, a massless particle can still have momentum because its energy E is related to its momentum p through the speed of light c. This relation reveals that massless particles must always travel at the speed of light (c).