We know that light is able to travel at great speeds, undetected by the human eye. But it’s natural to wonder what its stopping point is. Does light travel forever? This question can be approached from a few different perspectives.
Light can travel indefinitely, but it eventually loses its intensity. Being an electromagnetic wave, light is capable of penetrating and traveling through empty space without depleting its energy. Yet, when light is transmitted through a medium, the particles in the medium absorb some of the energy and transform it into heat.
This gradually diminishes the strength of the light until it disappears over time. Keep reading below for more exciting information about light, how it travels, and its intensity.
What is Light?
The electromagnetic spectrum that may be recognized by human vision is generally referred to as “light” or “visible light.” The electromagnetic spectrum covers an enormous range of energies and wavelengths, from millimeter-scale radio waves to sub-billionth-of-a-meter gamma rays.
Energy is transmitted through space at the speed of light (about 300,000 kilometers per second in a vacuum), and this phenomenon is known as electromagnetic radiation.
It is also possible to think of light as a stream of photons, which are packets of energy that don’t have any mass and move at the speed of light while exhibiting wavelike qualities.
The discovery that light traveled in discrete quanta, known as photons, was a key insight that led to the development of Quantum Theory.
For a more thorough explanation of light, watch this video below:
How Does Light Travel?
Light is a wave that can be transmitted from one location to another. These waves move in a transverse direction, just like the waves in a swimming pool. Light and the direction in which the waves vibrate are perpendicular to one another.
Light waves, in contrast to sound waves, are able to move across vacuums (empty space). They are able to move through anything that is transparent or translucent, even though they do not require a substance to travel through.
There are situations in which gravity can exert a pulling force on light without totally absorbing or reflecting it.
This is something that frequently occurs with black holes, neutron stars, and even big stars. When light travels by these objects, each of their individual gravities has the potential to exert a pulling force on the light.
If the distance between the light and the object is great enough, the light will continue to flow away from the object, but it will do so along a different path.
If you look down on a ray of light from above, you will see that the light is bending. This can be seen because the light is being affected by the phenomenon.
Hence, despite the fact that light moves in a straight line in all directions originating from an item, the gravitational pull of various objects might change where that light ultimately ends up.
Does Light Travel Forever?
The speed of light, an electromagnetic radiation wave, is approximately 299,792,458 meters per second (186,282 miles per second). It is not necessary for light to have a medium (like air or water) in order to spread, as it may do so via a vacuum.
Light does not weaken with the passage of time; nonetheless, it is possible for light to be absorbed, dispersed, or otherwise absorbed by objects, which can either lessen the light’s intensity or alter the path it takes.
The light emanating from a star that is billions of light-years distant from Earth, for instance, may be diminished by the dust and gas in intergalactic space. Moreover, the gravitational pulls of astronomical bodies like moons or stars may have an effect on the light.
Light, despite being absorbed or scattered, does not just vanish under these conditions. Instead, it undergoes a transformation into heat or motion energy.
Light is eternal since it cannot be created or destroyed but can be refracted, reflected, refracted again, or converted into another form of energy.
How Light Travels Forever
Since nothing can stop light in space and photons don’t “decay,” it stands to reason that the light will persist indefinitely.
But there is a much cooler explanation found in special relativity.
If you’re familiar with special relativity, you know that the faster anything travels, the slower its clocks tick from an outside observer’s perspective. When an object travels at a high pace, the length of the object shortens in the direction it travels; thus, time isn’t the only thing that is affected.
If you change your point of view and imagine yourself inside a spaceship traveling at roughly the speed of light, you won’t notice the slowing down and contraction of time happening to you; instead, it will appear as though the outside world is being sped up and squished along the direction in which you’re traveling.
As one approaches the speed of light, the magnitude of these effects grows.
When you reach the speed of light, the universe will have shrunk to an endlessly thin disc that you will be traveling through at right angles, and time will be moving at an endlessly faster rate throughout the rest of the universe.
Which is why, from the viewpoint of a photon, all of the locations it will visit are compressed into a single point, and the entire history of the universe occurs in the span of a moment.
Hence, the photon spends exactly zero time traveling from one location to another along its path. It can’t deteriorate since it gets where it’s going the instant it begins.
Does Light Fade?
In most cases, light does not fade in the sense of losing its energy. Absorption plays a role, although it’s not the main cause of loss. Light loses intensity, or “density,” as it travels farther and farther from its origin. Intensity is the quantity of light reaching a given surface.
The intensity decreases as the square root of the distance increases. This is analogous to how pond waves gradually lose height as they travel outward. Not much energy is being lost; it’s just being dispersed in a different way.
So, to conclude, light can indeed travel forever, but only if it does not get absorbed by another object in its way or get scattered. Furthermore, the farther light goes from its source, the more intensity it will lose.