Geissler Tube, an electron tube that is used to study the behavior of gases. It was invented in the 1860's by Heinrich Geissler, a German. The tube is made of glass, with an electrode at each end. Electricity is passed through a gas under low pressure within the tube; the color of the light produced depends on the kind of gas. Geissler tubes are used in physics demonstrations in high schools and colleges. They were forerunners of neon lights.
We take much for granted about our universe, like it's getting bigger. What if the universe stopped expanding and started collapsing inward with a giant crunch?
The big bang theory is well-known, but there are many misconceptions about it. Like what? Let's start with this one: There was no bang.