Question

What is the maximum possible mass that can be moved at the speed of light?

Answer 1

According to our current understanding of physics, it is not possible to move any mass at the speed of light. The theory of relativity, specifically Einstein's special theory of relativity, states that as an object with mass accelerates, its energy increases and its relativistic mass also increases. As an object with mass approaches the speed of light, its relativistic mass becomes infinitely large, requiring an infinite amount of energy to accelerate it to the speed of light.

This concept is expressed by the equation:

$m_{\text{rel}}=\frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}}$

where $m_{\text{rel}}$ is the relativistic mass, $m_0$ is the rest mass (or invariant mass) of the object, $v$ is its velocity, and $c$ is the speed of light.

As the velocity of an object approaches the speed of light ($c$), the denominator of the equation approaches zero, resulting in an infinitely large value for the relativistic mass. Thus, to move any mass with a non-zero rest mass at the speed of light would require an infinite amount of energy, which is not feasible.

Therefore, according to our current understanding, it is not possible to move any mass, regardless of its size, at the speed of light.