Question

hi everybody...
can EM waves propagate through perfect vacuum?
if so,how????

Answer 1

Of course they can! thats how we see everything in the universe (which is a vacuum). The light (EM waves) gets to us by traveling through a vacuum. They can do so because the changing electric field makes a changing magnetic field. But a changing magnetic field makes a changing electric field! Thus once one field is made to change in time, it makes the other, which in turn makes the other and so on. Thus the wave keeps itself "alive" as it goes through the emptiness of space (and also matter).

Answer 2

thanks for ur info sir.....
you mean to say fields can do mutual generation and then propagate
even for mutual generation also DON'T WE REQUIRE MEDIUM WHICH SHOULD NOT BE A VACUUM?

Answer 3

Yes, a kind of mutual generation. EM waves are different from usual waves in that they are not a medium "waving". For example sound is just the density of air changing along some direction of propagation. So without air (or any medium) sound waves cannot exist. EM waves are not the waving of a medium, they are electric and magnetic fields which can exist in a vacuum. This is why they travel at the same speed for everyone. You cannot move absolutely with respect to the vacuum, so the waves travel at the same velocity regardless of how one moves relative to the source. There was a time when scientists thought the same way you are proposing, that EM waves traveled in a medium, but Einstein proved that they do not.

Answer 4

but the EMF also trasfer energy(contains mass from Einstein), how can energy be free from universe ?

Answer 5

Well the waves are not "free" because according to Maxwell's equations you can trace every EM wave back to an electric charge accelerating or an electric current. So the vacuum only carries the energy made by some source of the wave (that might be far away) but they are not free, they all start somewhere and energy is required to make them start.

Answer 6

I would prefer to view this as a phenomenon which can be described by a ton of equations (e.g. Maxwell's Equations), however, I don't think you can truly explain WHY the propagation of EM waves can happen through a vacuum as the medium. The "nothingness" which we call "space" or vacuum could really be "something" else (see, theory of relativity, and space-time). But they are all theories. If you check up field theory and the mechanics behind the field, you may get more insights, but a lot of times Scientists are trying to describe nature but we aren't always able to explain fundamentally why nature is like that or why certain laws hold true.

Answer 7

perfect vacuum is not empty. Vacuum build space :) If you want water to drink -you use vacuum of cup.