Here's why:
* The speed of light is a constant: It doesn't change regardless of the motion of the source or the observer. This is one of the foundational principles of special relativity.
* Gravity affects spacetime, not the speed of light: Gravity warps the fabric of spacetime, causing objects to follow curved paths. However, light still travels at the same speed "c" through this curved spacetime. It's the path of light that gets altered, not its speed.
Think of it like this: Imagine a sheet stretched taut. If you place a heavy object on the sheet, it will cause a dip. Now, imagine rolling a marble across the sheet. The marble's path will be affected by the dip, but the speed of the marble itself remains constant. Similarly, light travels at a constant speed through the "dips" in spacetime caused by gravity.
So, whether in zero gravity, strong gravity, or anywhere else in the universe, the speed of light in a vacuum remains approximately 299,792,458 meters per second.
