How do waves travel in a vacuum?

In summary, according to the speaker, waves are energy. He doesn't understand how electromagnetic waves can travel through a vacuum, but he accepts that they do because otherwise we wouldn't be able to see things. He also wonders why physicists thought that an aether existed, and why it would have slowed the Earth down. Finally, he asks how two masses that are separated by a vacuum can attract each other and how two charges that are separated by a vacuum can attract or repel each other.
  • #1
MrPickle
56
0
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.
 
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  • #2
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.
 
  • #3
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/Michelson–Morley_experiment

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

Bob S
 
  • #4
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
 
  • #5
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?
 

1. How can waves travel in a vacuum if there is no medium?

Waves can travel in a vacuum because they do not require a medium to propagate. Unlike mechanical waves, such as sound waves, which require a material medium to travel through, electromagnetic waves can travel through empty space.

2. What is the speed of waves in a vacuum?

In a vacuum, all electromagnetic waves, including light, travel at the speed of light, which is approximately 299,792,458 meters per second.

3. Can any type of wave travel in a vacuum?

Yes, any type of electromagnetic wave can travel in a vacuum. This includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays.

4. How do waves behave in a vacuum compared to a medium?

In a vacuum, waves travel in a straight line and do not experience any changes in direction or speed. In a medium, waves can be refracted, reflected, or diffracted, which changes their direction and speed.

5. Are there any limitations to how far waves can travel in a vacuum?

As long as there are no obstacles or other interactions, electromagnetic waves can travel infinitely in a vacuum. However, as they travel through space, they may encounter other particles or objects which can absorb or scatter them, causing their intensity to decrease over long distances.

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