How can plasma the 4th state of matter be used to make earth a better place to live in?
Plasma is a relatively general term that characterizes many
things. However, in the context of your question, plasma is the
state of matter that the "fuel" is in when nuclear fusion takes
place. This is true at least in the most common designs for large
scale fusion reactors. Although nuclear fusion as an energy
production technology remains an unproven approach, it is promising
enough that people could hope that it "will make the earth a better
place to live in". That is mainly because: a) The source is
virtually unlimited (sea water) b) There no greenhouse gases (such
as CO2) released by fusion reactors c) The waste isotopes have a
half-life of hew decades making them reasonable to manage in
comparison with fission waste isotopes that have a half-life of
thousands of years. For more information on plasmas and fusion:
http://fusedweb.llnl.gov/CPEP/Chart_Pages/5.Plasma4StateMatter.html
http://en.wikipedia.org/wiki/Fusion_power