According to our current understanding of physics, it is not possible for an object with mass to travel at the speed of light in a vacuum without undergoing some form of acceleration.
As an object with mass approaches the speed of light, its relativistic mass increases, and more and more energy is required to continue accelerating it. As an object with mass approaches the speed of light, its energy requirements approach infinity, making it impossible to reach or exceed the speed of light.
This is a fundamental principle of special relativity, which states that the speed of light in a vacuum, denoted by "c," is the maximum speed that any object with mass can attain. Objects with mass can approach the speed of light but never reach or surpass it.
On the other hand, massless particles, such as photons, always travel at the speed of light in a vacuum. Since they have no rest mass, they can achieve and maintain the speed of light without any acceleration.
In summary, objects with mass require an infinite amount of energy to reach the speed of light, making it impossible to achieve without undergoing some form of acceleration. Only massless particles, like photons, can travel at the speed of light without acceleration.