Re: Why is an electromagnetic field a wave? Are the particles also waves?

Dear Ana Paula,

A brilliant physicist named Werner Heisenberg had the insight to realize 
that everything moves like both a particle AND a wave. We talk about 
electromagnetic waves-- radio waves, microwaves, X rays, visible light, 
etc. The particle that makes these waves is called a photon. You can think 
of it as a little piece of light. You have also probably heard about a 
particle called an electron-- there are electrons inside atoms. Physicists 
have done experiments that show that both photons and electrons act like 
both waves and particles. If you want more information, I suggest a 
textbook on Modern Physics, such as "Modern Physics" by Kenneth Krane.

As for your other question about tachyons, I'm not sure I understand it! 
If you can give me more details, I might be able to help.