Register to reply

How do waves travel in a vacuum?

by MrPickle
Tags: travel, vacuum, waves
Share this thread:
Jan15-10, 10:43 AM
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.
Phys.Org News Partner Physics news on
Symphony of nanoplasmonic and optical resonators produces laser-like light emission
Do we live in a 2-D hologram? New Fermilab experiment will test the nature of the universe
Duality principle is 'safe and sound': Researchers clear up apparent violation of wave-particle duality
Jan15-10, 10:57 AM
Sci Advisor
HW Helper
P: 8,953
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.
Bob S
Jan15-10, 11:28 AM
P: 4,663
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

So light propagates in empty space without any medium (aether or particles) to propagate it..

Bob S

Jan15-10, 04:13 PM
P: 2,466
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
Jan15-10, 05:09 PM
Redbelly98's Avatar
P: 12,069
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?

Register to reply

Related Discussions
Sound Travel in a Vacuum (not the obvious question) General Engineering 2
Amplitude of EM waves in vacuum ~ General Physics 2
Why Sound Doesnt Travel Through A Vacuum Introductory Physics Homework 3
How does light travel in a vacuum? Introductory Physics Homework 10
How does light travel in a vacuum? Introductory Physics Homework 1