Acceleration of an object to the speed of light.

I'm reading Pauling's General Chemistry and he starts off his first chapter with, "Matter may be defined as any kind of mass-energy that moves with velocities less that the velocity of light, and radiant energy as any kind of mass-energy that moves with the velocity of light."



I know that we can't accelerate an object to the speed of light, but the wording of this sentence seems to imply that, if we could, it would become radiant energy; as it would then be mass-energy moving with the velocity of light.



So my question is, if we could accelerate an object to the speed of light would it become radiant energy?