Quantum Physics For Dummies, Revised Edition

Chapter 1

Discoveries and Essential Quantum Physics

In This Chapter

• Putting forth theories of quantization and discrete units
• Experimenting with waves acting as particles
• Experimenting with particles acting as waves
• Embracing uncertainty and probability

According to classical physics, particles are particles and waves are waves, and never the twain shall mix. That is, particles have an energy E and a momentum vector p, and that's the end of it. And waves, such as light waves, have an amplitude A and a wave vector k (where the magnitude of k = , where λ is the wavelength) that points in the direction the wave is traveling. And that's the end of that, too, according to classical physics.

But the reality is different — particles turn out to exhibit wave-like properties, and waves exhibit particle-like properties as well. The idea that waves (like light) can act as particles (like electrons) and vice versa was the major revelation that ushered in quantum physics as such an important part of the world of physics. This chapter takes a look at the challenges facing classical physics around the turn of the 20th century — and how quantum physics gradually came to the rescue. Up to that point, the classical way of looking at physics was thought to explain just about everything. But as those pesky experimental physicists have a way of doing, they came up with a bunch of experiments that ...