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Why can no material object reach the speed of light?

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Brian Greene sits in a living room, holding a pen, with handwritten equations m = E/c^2 and E = mc^2 on a whiteboard beside him, highlighting c^2 as the speed of light. — relativity Brian Greene kicking off his *Your Daily Equation* video series with Albert Einstein's famous equation E = mc².

According to the theory of special relativity, no material object can reach the speed of light because it acts as a cosmic speed limit for the universe.12

As an object with mass accelerates, its relativistic mass increases. As its velocity approaches the speed of light, this mass approaches infinity. Consequently, the energy required to continue accelerating the object also increases toward infinity. Because it would take an infinite amount of energy to accelerate a material body to the speed of light, it is physically impossible for any object with mass to reach or surpass that speed.132

In contrast, light itself can travel at this speed because the photon—the particle of light—has a rest mass of zero.1