If there is no resistance in space why is does light only travel 300,000 km/sec ?


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 ?

In: 1092

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.


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.