|MadSci Network: Physics|
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.
Try the links in the MadSci Library for more information on Physics.