Converting just one gram of matter entirely into energy would release the explosive power of an atomic bomb.

Albert Einstein introduced the concept of mass-energy equivalence in 1905 as part of his Special Theory of Relativity. The equation E=mc² states that energy equals mass multiplied by the speed of light squared. Since light travels at approximately 300,000 kilometers per second, the value of c² is an astronomical 90 quadrillion meters squared per second squared.When one gram of matter is converted entirely into energy, it releases about 90 terajoules, roughly equivalent to 21.5 kilotons of TNT—slightly more powerful than the "Fat Man" atomic bomb dropped on Nagasaki in 1945. That bomb used about 6.4 kilograms of plutonium, but only about one gram of that mass was actually converted into energy during the fission process.In everyday life, this energy remains locked within atomic structures by strong and weak nuclear forces. We only observe this conversion in extreme environments like the Sun's core or inside nuclear reactors. In the Sun, four million tons of matter are converted into energy every second through nuclear fusion, providing the light and heat necessary for life on Earth.The efficiency of energy release varies by process. Chemical reactions, like burning coal, release less than a billionth of the mass energy. Even nuclear fission, the most powerful process we have harnessed for power generation, converts only about 0.1% of fuel's mass into energy. A total conversion of matter to energy would require an encounter between matter and antimatter, which is currently impossible to achieve on a large scale.