# Question #8212b

Feb 10, 2016

No. On the contrary it appears heavy.

#### Explanation:

It is a case of quantum mechanics.

Whenever speed of an object is comparable to the speed of light the laws of classical mechanics are no longer valid with rest mass ${m}_{\circ}$in the equations.
For such cases the

${E}_{t o t a l} = \gamma . {m}_{\circ} {c}^{2}$
where Lorentz factor $\gamma \equiv \frac{1}{\sqrt{1 - {v}^{2} / {c}^{2}}}$

Lorentz factor $\gamma = 1$ only for small values of velocity when ${v}^{2} / {c}^{2}$ in the denominator is small and can be ignored.

Observe what happens to the value of Lorentz factor when $v = c$. It is a singularity.