Perception Of Time
Usually, when we think of subjects like light and time and light and its relationship to time, if we think of them together at all, they seem disparate. Time we associate with something on a clock face or as something that measures now to another point, as in terms of how much time we have until an appointment or how many hours there are until we can stop work and do something else. Light, on the other hand, we associate with a switch on a wall, the Sun, or positivity. Maybe we think of it as the opposite of night.
However, light and its relationship to time are much closer. You see, science teaches us that the way we recognize something is when light travels from an object or a person to our eyes, and our brain interprets what we are seeing based on past experience association or some other knowledge.
The only way we are able to see anything is through light that originates with a source. The source shines on something and then we see it. Without light, we are quite literally blind, even if that light is very dim.
Light and its relationship to time is also varying based on the type of light. Our eyes cannot see ultraviolet light without the aid of certain lenses which convert the waves of photons into frequencies and ranges that our particular eyes can see. Other creatures, such as deep-sea fish, can see with greater clarity. Predators often see better at night than we do. All this tells us that the speed at which light travels to our eyes, from an object, is crucial. Even though this happens literally at 186,000 miles per second, the speed of light is vital to how we recognize things. Likewise, if something like a black hole whose gravity is so dense even photons, or the components of light cannot escape it, acts upon light, then time, a component reliant upon light, will cease.
Time Dilation
The phenomenon known as time dilation demonstrates that different devices, such as two clocks, will show the same time UNLESS they are acted upon by other forces able to harness and manipulate light. Therefore, time dilation is defined as what happens when those two clocks show different times due to different velocities at which they are moving, or by gravity differences between their locations.
This is even notable if a clock is moving away from us, say, in a car. Were we able to observe our watch and the clock in the car simultaneously, the clock in a car would seem to tick slightly slower simply because the light reaching our eyes from the clock face, would be reaching our eyes slightly more slowly. Moreover, in the same way, a clock that is closer to a massive object, such as a planet, will show a time that is different than one that is farther away from the massive object. This is because gravity exerts a force on light traveling from the massive object. The farther away from the planet, the less gravity from the planet exerts itself on light. This is why black holes, so dense and so violently gravitational, literally stop time. Nothing escapes them, not even light. So, if we were able to look at an object falling into a black hole, the object, just before it falls in, would seem to stop, grow dim, and then remain that way for millions of years. Light and its relationship to time demonstrates that the light that travels from the object falling to our eyes would be arrested and sucked in by the black hole, and only the tiniest bits of photons would escape, just enough for us to see the object on the edge of the black hole, but never see it disappear, because light enables us to see things disappear, also.
From the Sun, light takes eight minutes to reach Earth. So, when youre standing outside during the day, the light you see reflecting off of trees or your hand, left the Sun eight minutes ago. The sun is 93 million miles away, so its light takes 8 minutes to reach us, even though light travels the fastest of anything known to us, and nothing, science tells us, can break that speed. To put it another way, if the Sun were to all of a sudden stop shining, we would not be aware of this change for a full 8 minutes. Light and its relationship to time is much more close in nature than we realize.
Photons
What would happen though, if we were to consider light from the perspective of a photon? Would this change questions or answers about light and its relationship to time? This is where Einsteins Theory of Special Relativity gained such notoriety by demonstrating that the relationship to time that light bears, is completely relative to forces acting upon light.
Photons, despite being the components of light, do not move close to the speed of light but rather they move precisely at it. So, we might ask, how much light has a photon given off by the time it reaches us on Earth, from the Sun? If you say 8 minutes worth, science would reply perhaps in agreement, IF we still thought of light and its relationship to time as Isaac Newton did. But if Einsteins theory had not shown differently, we would think that all things in the universe experience light in the same way, passing at the same rate. But this isnt true according to Einstein. The speed of light is constant, he showed.
Hence, if you imagine yourself shining a flashlight at an object that is one light-minute away, you would think that light would move at the speed you are running and at the speed of light at rest. But the facts show that as you run, time will seem to slow. You can also consider the following:
I want you to imagine that youve got a clock, only instead of having a clock where a gear turns and the hands move, you have a clock where a single photon of light bounces up-and-down between two mirrors. If your clock is at rest, you see the photon bouncing up-and-down, and the seconds pass as normal. But if your clock is moving, and you look on it, how will the seconds pass, now?
Quite clearly, it takes longer for the bounces to occur if the speed of light is always a constant. If time ran at the same rate for everyone, everywhere and under all conditions, then wed see the speed of light be arbitrarily fast the faster something moved. And whats even worse, is if something moved very quickly and then turned on a flashlight in the opposite direction, wed see that light barely move at all: itd be almost at rest.*
But light does not change its speed in a vacuum. In fact, the faster something moves, the closer to the speed of light it is going. So, someone standing and watching will view time as passing normally. But the relationship of light and time shows that if someone were moving at the same speed as an object moving away from you, time would seem shorter. If you were meeting someone somewhere, and your friend was staying behind, if you traveled at the speed of light to meet your other friend who was an hour away, assuming that your watches were showing the same time when you set out, your friend at home would show an hour behind you when you reached your destination. This is the effect of relativity, a kind of harness and mitigator of light and its relationship to time.
Einstein also noted that objects do not move through space or time, but rather they move through both as a unified entity he called spacetime. Spacetime governs light and its relationship to time along with gravity. Kind of gives a new meaning to two things that we usually think of as unrelated, eh? So the next time someone says something along the lines of time equaling money, you can think also that time equals light in more ways than we usually think.
Informational Sources:
Nasa.gov
Space.com
Forbes.com*
Physicstoday.com