So a rocket moves by having a big explosion push it. A car moves by little tiny explosions moving things and then mechanics to get it to the wheels, how does light power itself to move? especially with how fast it moves?
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Light isn’t accelerating. Cars and rockets are. A photon’s momentum and kinetic energy are part of the photon, and are imparted to it instantly as the photon is created in some interaction between particles. Ultimately, it “pushed off” of the particle that emitted it; that particle gets a slight recoil in the other direction (usually a pretty small one, since the momentum of a photon is typically small compared to the momentum of typical particles).
You’re not quite right here. Rockets and cars both usually move because they were already moving and nothing has stopped them. Only when they need to change course do they need to push on something.
Rockets push off of their own fuel. Planes push off of air. Cars push off of the ground. When they need additional energy to do what they’re doing, they will burn fuel.
Light never needs extra energy to continue being light.
Light doesn’t move–it only looks like it moves to those of us with mass. Imagine yourself accelerated faster and faster approaching the speed of light. Lengths in your direction of travel get smaller and smaller due to length contraction (you can look at it as time stops if you prefer). If you’re going fast enough, trillions of light years could be no longer than the width of a proton.
Move is a vague term. It could mean either acceleration or velocity, or both. Acceleration is something changing its velocity, either the speed itself or the direction.
A car accelerates with tiny explosions. It decelerates with friction of the road, air resistance, or brakes. Rockets accelerate or decelerates with big explosions. When none of those things apply, like a rocket or car in space, it is still moving with its velocity, it’s just not accelerating or decelerating.
Light doesn’t change its velocity, it can only change direction. It has “infinite” velocity. From the moment it comes into existence to the moment it disappears, a photon is moving at the same speed, “infinite”. There’s a bit of misnomer when we say the speed of light is about 300,000 km/s. That speed is the fastest anything can move in the universe, not just light. Even the effects of gravity moves at this speed. It’s why it’s referred to as the speed of causality. If the sun simply vanishes with all its mass, it will take approximately 8 minutes for the earth to stop orbiting where the sun used to be. Light when you think of it a certain way has “infinite” speed, but the speed of light is finite because it is being restricted by the universal speed limit. If scientists increase the speed of causality, light will move faster to match it (kudos if you get the reference).
Light is a self-propagating change in the electric and magnetic field. When the electric field changes, it causes the magnetic field to also change. When the magnetic field changes, it causes the electric field to change. It’s a self-feeding cycle that repeats until something interrupts it, like running into an electron. We use this relationship everyday, it’s what allows us to make electricity using generators and electric motors move. The change happens almost instantaneously, but the universal speed limit prevents it from being truly instant. Light moves because it has energy. Much like how that spaceship or car continues to move through space without those explosions if it has kinetic energy and nothing else runs into it. But because light has no mass, it has “infinite” speed. The only reason that car or spaceship isn’t travelling at the speed of light is because they have mass. If they didn’t have mass… They would be moving at the same speed of light but as far as we can tell the only way to do that is to have it run into its antimatter equivalent and turn itself into pure energy.
When you throw a rock into a pond you get waves that ripple out from where you threw the rock. If you throw a bigger rock you get bigger waves, but the waves don’t move any faster. That the waves exist at all is because you threw a rock into the pond and the height of the waves is due to the size of the rock/how hard you threw it, but how fast the waves move away from the place where the rock hit the water is due to the properties of the water (and stuff like how strong gravity is).
Light is the same way, but the waves are 3d waves in the electromagnetic field instead of the surface of the water. The waves exist because the field was perturbed by something, generally an accelerating electric charge and the speed is due to the properties of the field.
Light didn’t start stationary and then accelerate up to some speed, it was always at that speed because that’s the speed perturbations of the EM field move at!
A rocket does not need a big explosion to move. It needs the big explosion to get it up to its final speed. When it’s in space, it will continue to move forever with no added fuel, because there is no air friction to slow it down.
Cars need fuel to move because they are on the surface of the Earth, so they are constantly experience friction. If they were launched into space they could move forever with no fuel, but on the surface of the Earth they keep needing extra energy to overcome air and ground trying to slow it down.
Light is made of tiny particles. They can be absorbed by matter, but other than that, they experience no friction – at that scale there is nothing to experience friction with. Once created, they will move at a constant speed forever until something diverts them.
atoms are made up of electrons and protons. These are charged particles, which mean they have an electric field around it. If you jiggle an electron it’ll jiggle its electric field. A jiggling electric field causes a jiggling magnetic field. But also a jiggling magnetic field causes a jiggling electric field.
So when you jiggle an electron, that causes a jiggling electric field, which causes a jiggling magnetic field, which causes a jiggling electric field…. on an on. This is an electromagnetic wave, otherwise known as light. The electron is pushed back by the electric and magnetic field of the wave.
The energy within the electromagnetic wave came from the jiggling u did to the electron. the wave doesnt need to keep powering itself to keep going since it is just the the interreaction of electric and magnetic fields that it itself are constantly creating. And if theres nothing to stop it, itl just keep going and never slow down.
You create an electric field, which automatically creates a magnetic field, which automatically creates an electric field ad infinitum.
The rate at which an electric field is generated and the rate at which the magnetic field is generated combine to give a speed of 299,792,458m/s in a vacuum.
Light is special because it has no mass. Light cannot be compared to other objects. Light can only ever move at the speed of light in whatever medium its traveling through. Light can never be still and it requires no acceleration to reach that speed. The instant it comes into existence, it’s moving at the speed of light. The laws of physics show that light simply has to move at that speed and it always does.
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