Traveling at the speed of light, or even approaching it, poses significant challenges according to our current understanding of physics. The theory of special relativity, formulated by Albert Einstein, implies that as an object with mass approaches the speed of light, its relativistic mass increases, requiring an infinite amount of energy to reach the speed of light itself. Additionally, time dilation effects become more pronounced, making it practically impossible for an observer on board the spacecraft to experience such speeds.
Furthermore, the concept of a spacecraft that doesn't rely on conventional propellant and can travel at the speed of light is purely speculative at this point. While science fiction often explores concepts like warp drives or wormholes for faster-than-light travel, there is currently no scientific consensus on the feasibility or practicality of such technologies.
It's important to note that even if we were to discover new physics or propulsion methods in the future, it would still be subject to the laws and limitations of the universe. Until we have a more comprehensive understanding of the fundamental laws of physics, including gravity, space-time, and the nature of energy and matter, the concept of traveling at or near the speed of light without conventional propellant remains purely hypothetical.
However, it's worth mentioning that scientific progress is ongoing, and our understanding of the universe continues to evolve. While it's impossible to predict what breakthroughs may occur in the future, it's essential to approach such speculative ideas with a critical and cautious mindset, considering the current knowledge and limitations of our scientific understanding.