In the grand body of the universe and even our own solar system the speed of light is incredibly slow on the cosmic scale. Why does it have this speed limit ? It is theoretically possible to go faster than light ? Or is light just the fastest thing we have observed thus far ?
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Light (and all other electromagnetic radiation) depends on the “conductivity” of both magnetism and electricity in a vacuum. Light can’t travel any faster than electricity can generate magnetism or magnetism can generate electricity.
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The first part of your question was answered, to address the other parts:
By current understanding of physics, nothing with (resting) mass can travel even AT the speed of light, and only photons can reach the speed of light.
There’re theories about reaching the speed of light, but they rely on loopholes around other theories, and seem to suggest making a wave in spacetime and surfing that wave, so really you’re not moving at all, you’re manipulating spacetime to move you.
Light is the speed of causality, which is how an effect follows a cause (you drop a ball is the cause, it starts falling is the effect). If something went faster than light, the cause would take place after the effect (a ball starts falling, and afterwards you drop it)
Imagine that you are sitting on a boat in a lake and you toss a pebble in the water. When it hits, you will see the ripples spread out at a constant speed. It doesn’t matter how big the rock is or how hard you throw it, the waves will always travel the same distance in the same amount of time. Even if no energy is lost, it takes time for the disruption to travel from the contact point to the rest of the pond.
It turns out that our universe works in much the same way. Most of what we observe in our day-to-day lives, from gravity, to light, to matter itself, can be modeled by waves in a field. These waves behave much like waves in the water. The speed of light is the speed that waves can travel through that field. Nothing can travel faster than the speed of light because nothing can travel faster than the waves that carry information throughout our universe.
Going back to the water analogy, we are like leaves on the surface of the pond. If we get hit by a wave, we may get moved by it. If we get hit by a lot of waves, we may start to move faster. However, there is no way for us to get moving faster than the waves in the pond when they are the only thing that is able to push us along.
The speed of light is really the speed of causality and the speed of propagation of information.
Light is made of photons which are massless. As a consequence of their lack of mass they travel at the fastest speed possible in our universe.
This is an artifact of how we measure the speed of light. Briefly, what we actually do is measuring patterns across moments in time. Doing so we divide spacetime (a single, unified entity) into space and time. It’s really hard to not fall in this trap, because the concept of time is so embedded in our perception. Velocities are not additive at high values close to the speed of light.
If you were to use the right tools to measure the “speed” of light, as is done in relativity, the answer would be infinity. This is the so called “rapidity”, which is a generalization of speed for relativistic speeds. There is no limit to the “rapidity” quantity. From our reference frame this is equivalent to say that light rays don’t experience time passing, but since we are measuring that process as beings experiencing time, the comparison leads us to infer a maximum speed limit. Again, this is simply an artifact of our limitations and the scale of the unvierse at which we exist.
Another issue with the speed of light is that in General Relativity is that the speed (as we mean in 3D space + 1D time, i.e. 300000 km/s) is not at all constant: it varies with gravitational potential as measured by distant observers, which in turn is the cause of gravitational time dilation. Light is slower, hence the speed at which information travels is slower, so everything happens in slow motion compared to other places where the speed is higher.
Back in 4D spacetime, we use 4-velocity, which doesn’t change and it is always equal to c^2 in magnitude.
It’s not slow on a cosmic scale – from the photon’s perspective it literally takes 0ms to travel any distance. I’d say that’s as fast as it can get! If you observe the photon from Earth it might seem slow, but the photon experiences all time as instant.
Light travels at that speed because it’s the speed of causality, as in: the fastest something can happen as a result of something else happening.
Some things others haven’t mentioned yet: this maximum speed limit has some weird properties as well. There is a variable called the Lorentz factor that can account for how things get harder to accelerate as you approach the speed of light. This is an issue because it means to be *at* the speed of light you’d need to actually have infinite energy (since we have mass unlike photons). Also, as something accelerates close to the speed of light, time slows down for the person accelerating relative to the people not accelerating, an effect called time dilation. This is because of another weird effect light has which is that it is always observed as the same speed no matter the speed of the observer. This is counterintuitive because when you think of for example a person running and throwing a baseball, you can add the speeds of the person and the throw together to get the speed of the ball. However this actually doesn’t happen to light. Even if we were going extremely fast, light would always seem to be going much faster because it kinda slows down time in a way in order to keep that rule
Light speed is just how our universe works. It’s like a universal speed limit set by the laws of physics. This speed – 300,000 kilometers per second – comes out of the equations of Einstein’s theory of relativity, which describes how space and time are connected.
It’s not about resistance, it’s about the nature of space and time themselves. According to current understanding, nothing can move faster than light. If something could, it would mess up the cause-and-effect in our universe and violate the theory of relativity.
So yes, as far as we know, light (and other electromagnetic waves) is the fastest thing in the universe.
First, forget the term light speed. Light is just one of the many things that travels at this speed. The term is the speed of causality or the fastest any information can move though space.
As you move faster through space, you move slower through time. At the speed of light, you don’t experience time at all. To something moving at light speed, it arrives at its destination instantly. You cannot move faster than instantly. It is only to the viewer that it seems to move at a slower rate of time. A stationary viewer sees it as 300k km per second because you experience a different second. At the speed of causality, there is no movement through time and so you cannot go faster.
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