Why can't anything travel faster than the speed of light?

The reason why nothing can travel faster than the speed of light is rooted in several key concepts from Albert Einstein's theory of special relativity.

Spacetime and Universal Speed Limit

According to special relativity, space and time are unified into a single entity called spacetime. Every object moves through this spacetime at the speed of light, but the distribution between movement through space and time varies. A stationary object moves through time at the speed of light, while an object moving through space at high speeds moves less through time. Essentially, the total speed through spacetime remains constant, and you cannot exceed this speed by moving more through space because there is no additional speed to gain once you are moving at the speed of light through space24.

Mass Increase and Energy Requirement

As an object approaches the speed of light, its mass increases due to the Lorentz factor (γ). This increase in mass means that it becomes progressively harder to accelerate the object further, requiring more and more energy. At the speed of light, the mass would become infinite, and the energy required to achieve this would also be infinite, which is physically impossible135.

Fundamental Limitation

The speed of light (approximately 299,792,458 meters per second) is a universal constant and serves as the upper limit for the speed at which any conventional matter or energy can travel through space. This is not just a practical limit but a fundamental one, inherent in the structure of spacetime itself. Only massless particles, such as photons, can reach this speed135.

In summary, the combination of the unified nature of spacetime, the increasing mass of objects as they approach the speed of light, and the infinite energy requirement to reach the speed of light, all contribute to the cosmic speed limit imposed by the speed of light.