2. Anti-matter
Anti-matter is our universe’s arch-nemesis. When anti-matter and matter combine, they annihilate each other and their total mass becomes pure energy. Based on Einstein’s iconic equation E=mc2, anti-matter is also the greatest source of energy or the most violent explosive known to man. Anti-matter could only be stored in a special container made from intense electromagnetic field to avoid contact with the physical container, which is made from matter. Consequently, anti-matter is the most expensive material to produce, which is about $25 billion per gram of positron (anti-electron). More complex anti-matter, such as one gram of anti-hydrogen, costs more than $60 trillion!
