What is Plasma (physics)?
'''Plasma''' is the 4th [[state of matter]]. [[Image:Plasma-lamp 2.jpg|thumb|right|A [[plasma lamp]], showing some of the more complex things a plasma can do. The colors come from the [[gas]] in the lamp. Each type of gas makes a different color]] [[File:NeTube.jpg|thumb|[[Gas-filled tube]]s often contain plasma. This one shows [[neon]]. The color of the tube gives a hint to the gas inside]] Plasma is created by adding energy to a gas so that some of its electrons leave their atoms. This is [[ionization]]. It results in negatively charged [[electron]]s, and positively charged [[ion]]s. Unlike the other states of matter, the charged particles in a plasma react strongly to electric and magnetic fields (i.e. [[electromagnetic field]]s). If a plasma loses heat, the ions will re-form into a gas, emitting the energy which had caused them to ionize. Over 99% of the [[matter]] in the [[Observable universe|visible universe]] is believed to be plasma. When the [[atom]]s in a gas are broken up, the pieces are called [[electron]]s and [[ion]]s. Because they have an [[electric charge]], they are pulled together or pushed apart by [[Electricity|electric fields]] and [[magnetic field]]s. This makes a plasma act differently from a gas. For example, magnetic fields can be used to hold a plasma, but not to hold a gas. Plasma is a better [[Electrical conductor|conductor]] of electricity than copper. Plasma is usually very hot, because it takes very high [[temperature]]s to break the bonds between electrons and the nuclei of the atoms. Sometimes plasmas can have very high [[pressure]], as in [[star]]s. Stars (including the [[Sun]]) are mostly made of plasma. Plasmas can also have very low pressure, as in [[outer space]]. On [[Earth]], [[lightning]] makes plasma. Artificial (man-made) uses of plasma include [[fluorescent light]] bulbs, [[neon signs]], and [[plasma display]]s used for [[television]] or [[computer screen]]s. Plasma lamps and globes which are popular children's toys and room decorations. Scientists are experiment