# How do waves travel in a vacuum?

by MrPickle
Tags: travel, vacuum, waves
 P: 48 Today in class we started talking about waves. I understand waves to be energy. This makes sense to me when thinking about sound waves, because the energy can travel from one particle to the next to travel; but I don't understand how things like electromagnetic waves can travel through a vacuum. The wave's energy can't be passed from one particle to the next because there are no particles in a vacuum and I don't understand how the energy could move because well, it's energy. I accept that it travels because otherwise we wouldn't be able to see the planets and Martians and what-not. Is this something to do with E=mc2? Do we even know the answer? This isn't a homework question, just me questioning things, but it's still related to school so I'm sorry if this is the wrong place.
 HW Helper Sci Advisor P: 8,962 Thats where thinking of light as a wave isn't useful. Think of a photon as a little bullet that is vibrating with a certain frequency, the wavelength is then just this frequency * the speed of the bullet. One good analogy is to think of a police car with a flashing light driving along a street. The light flashes with a certain frequency and the car goes at a fixed speed. If you mark on the road the position of the car everytime the light flashes - this gives a wavelength, but it doesn't mean the car is this long.
 P: 4,667 At one time, physicists thought that empty space was filled with "aether", and there was a preferential reference frame where the speed of light was constant. The Michelson Morley experiment disproved this, and verified that the speed of light was indeed constant = c in every inertial frame. See http://en.wikipedia.org/wiki/Michels...ley_experiment So light propagates in empty space without any medium (aether or particles) to propagate it.. Bob S
P: 2,422

## How do waves travel in a vacuum?

I think it is weird that they thought they wan an aether because if there was it would have slowed the earth down to a stop , the earth wouldn't have been able to go around the sun . , the electromagnetic field is doing the waving
 Mentor P: 11,912 This is a little like asking, how can two masses that are separated by a vacuum attract each other gravitationally? Or more on topic, how can two charges that are separated by a vacuum attract or repel each other?

 Related Discussions General Engineering 2 General Physics 2 Introductory Physics Homework 3 Introductory Physics Homework 10 Introductory Physics Homework 1