According to our current understanding of physics, both the speed of light and infinite velocity are considered unattainable for different reasons:
Speed of Light: In the theory of special relativity, formulated by Albert Einstein, the speed of light in a vacuum, denoted as 'c', is considered to be an absolute cosmic speed limit. Particles with mass cannot reach or exceed the speed of light because as an object with mass accelerates, its energy requirements approach infinity. This means that the amount of energy needed to accelerate an object to the speed of light becomes infinite. Thus, according to our current understanding, anything with mass would require an infinite amount of energy to reach or exceed the speed of light.
Infinite Velocity: Infinite velocity, by definition, means traveling at an unlimited speed. However, this concept violates our understanding of space, time, and causality. Infinite velocity implies that an object would travel an infinite distance in a finite amount of time, which contradicts our understanding of the structure of space and time. Additionally, infinite velocity would also result in infinite energy requirements, as discussed earlier. Infinite velocity is not supported by our current scientific theories and would lead to paradoxes and inconsistencies.
It is important to note that our understanding of the universe is based on the currently accepted laws of physics, but scientific knowledge is subject to revision and advancement. Future discoveries or new theoretical frameworks may provide insights that challenge our current understanding and allow us to revisit these concepts. However, based on our present knowledge, both the speed of light and infinite velocity are considered unattainable.