On Earth we experience three of the four states of matter constantly: solid, liquid and gas. There is a fourth state of matter that is rare on Earth but actually makes up 99.99% of the visible matter in the Universe and was the first state of matter to form after the Big Bang: Plasma.
Examples of three forms of plasma:*
- Astrophysical: All Stars, Solar wind, Interstellar nebulae,
- Found on Earth: Lightning, Auroras, the Ionosphere, extremely hot flames
- Artificially Produced: Plasma TVs, Fluorescent lighting, Neon signs, Plasma torches for cutting and welding,
To understand plasma, it is best to revisit solids, liquids and gasses.
The differences between these states of matter have to do with their molecular structure. A solid has regularly structured molecules in a crystalline structure. When a solid is heated to it’s melting point (for water 32 degrees), it loses is crystallized structure and the molecules move independently from each other but don’t separate completely from other atoms. At boiling point (212 degrees for water) there is so much kinetic energy that the molecules fly around and bounce off each other resulting in a gaseous state. From a molecular viewpoint, here’s how water looks as a solid, liquid and gas:
Like a gas, plasma has no fixed shape or volume, but unlike a gas, atoms in plasma have been stripped of their electrons thus are just positively charged nuclei (i.e. ions) and freely roaming electrons. Plasmas have very different properties than gasses due to its highly charged state.
Plasmas differ from gasses in a number of important ways:*
- Plasma has a very high electrical conductivity.
- Plasma is more readily influenced by electric and magnetic fields than by gravity
- The motion of electrons and ions in plasma produces its own electric and magnetic fields.
- Because of the totally chaotic and highly energetic state of the constituent particles of plasma, it produces its own electromagnetic radiation.
Plasmas occur naturally but can also be artificially made. In the case of florescent lighting and neon signs, gas is “subjected to a high voltage, and the electrons are either separated from the atoms of the gas or pushed into higher energy levels. The gas inside the bulb becomes a conductive plasma. The excited electrons that drop back into their previous energy levels emit photons – the light we see in a neon sign or fluorescent lamp.”** Plasma TVs work similarly – electric charge is used to strip gas of its electrons and then manipulated to cause different colored light to be emitted.
Related IFOD on Ice: Ice Ice Baby!
*Lists from the Science Learning Hub.
**Quote from Live Science