Light, in the form of electromagnetic radiation, continues to travel through space until it encounters an obstacle or is absorbed by a material. In a perfect vacuum with no obstructions, light can theoretically travel indefinitely without fading or dissipating.
This concept is often referred to as "infinite propagation." In the absence of interactions with matter or other energy-loss mechanisms, light maintains its intensity and wavelength as it travels through space. This property allows light from distant sources, such as stars and galaxies, to reach us over vast cosmic distances.
However, it is important to note that various factors can affect the perception or detection of light. One such factor is the expansion of the universe, which causes light waves to stretch or redshift as space itself expands. This redshift can change the observed wavelength of light, impacting how we perceive it. For extremely distant sources, the expansion of the universe can cause their light to become significantly redshifted, shifting it into longer wavelengths such as infrared or even radio waves.
Furthermore, as light travels through space, it can encounter dust, gas clouds, and other interstellar or intergalactic material. These materials can absorb or scatter light, leading to its attenuation or redirection. In some cases, light can be completely absorbed, preventing it from reaching us. This is particularly relevant for certain wavelengths of light, such as ultraviolet and X-rays, which can be absorbed by Earth's atmosphere.
In summary, under ideal conditions in a vacuum, light can propagate indefinitely without fading or dissipating. However, various factors, such as the expansion of the universe and interactions with matter, can affect the perception or detection of light, potentially altering its characteristics or preventing it from reaching us.