Yes, according to the currently accepted scientific theory of special relativity, the speed of light in a vacuum is constant and does not depend on the direction of propagation or the motion of the source or observer. This fundamental principle is known as the constancy of the speed of light.
In a vacuum, the speed of light is approximately 299,792,458 meters per second (or about 186,282 miles per second). This value is denoted by the symbol "c" in physics.
The constancy of the speed of light has been confirmed by numerous experimental observations and is a foundational principle in modern physics. It has important implications for our understanding of space, time, and the behavior of objects moving at high speeds.
According to special relativity, as an object with mass approaches the speed of light, its relativistic mass increases, and its length contracts in the direction of motion. These effects are a consequence of the constancy of the speed of light and play a crucial role in the theory of relativity.