Gravity. It's the law.

14-billion-years-later:

Crooke’s Tube

Although chemistry has some pretty awesome glassware you don’t get the same light shows as you do in physics. The above image shows a Crooke’s tube which is a fairly simple piece of equipment for playing around with electrons. At one end of the tube we have an electrical current which ionizes the small amount of air particles in the tube creating ions and electrons. At either end of the tube we have two plates with opposite charges creating an electric field. This has the effect of accelerating the charges to either end of the tube, positive charges to the negatively charged plate and vice versa. At the end the electrons move to the glass has been coated with a phosphor that emits photons when struck with electrons to create an eerie green glow. Interestingly enough the glass itself will also radiate light when struck with electrons but much less intensely. At gas pressures above 0.1 of an atmosphere a glowing in the gas itself can also be noticed.