Any SAT Physics Experts Here?

<p>I don't understand de Broglie wavelength. How can a particle have a wavelength? Wouldn't that mean the particle is really a wave, like a wave that moves up and down in the ocean? How can that be? Waves in the ocean are made up of lots and lots of particles of water. I'm just extremely confused about this. And according to de Broglie, if I threw a baseball, it would have a wavelength. I have absolutely no clue what that even means. I always think of waves as water waves that move up and down.</p>