article_snippet: Often called the fourth state of matter, plasma is a state of matter where heat or another energy has been added to a gas.
article_snippet: a gas is said to be ‘ionised’, and when enough atoms are ionised, a gas is said to be a plasma.
article_snippet: Interestingly, plasma is thought to make up more than 99 per cent of all matter in the universe.
article_snippet: In so doing, the plasma between the regions of different density produces pressure pulses, or a sound wave.
article_snippet: In fact, plasma is thought to make up 99 per cent of matter in the universe .