Here's why:
* Constant Speed: Light travels at a constant speed in a vacuum, approximately 299,792,458 meters per second. This speed doesn't decrease over distance.
* No Friction: Light doesn't experience friction like objects moving through air or water. There's nothing slowing it down.
* Universe Expansion: The universe is expanding, and this expansion can cause light to redshift (its wavelength to stretch), but it doesn't stop the light from traveling.
However, there are some practical limits:
* Obstacles: Light can be absorbed, reflected, or scattered by objects it encounters.
* The Age of the Universe: The universe has a finite age, meaning there's a limit to how far light from the earliest events can have traveled. This defines the observable universe, the region we can see.
Therefore, while light theoretically can travel infinitely, we can only observe light that has reached us within the finite lifespan of the universe.
