Tag: E mc2

A matter-antimatter annihilation, converting 100% of mass to energy ($E=mc^2$), represents the ultimate theoretical energy density known to physics. This extreme concentration, vastly surpassing all other forms, highlights a complex hierarchy of energy sources across the universe.

According to a viral online myth, a single gram of uranium contains up to 20 billion calories of energy. This figure is a gross misinterpretation of nuclear physics and bears no relevance to dietary calories, which are used by the human body for metabolism. In reality, consuming uranium provides zero metabolic energy and is, in fact, extremely toxic.

A single gram of matter, if fully converted to energy via Einstein's equation ($E=mc^2$), contains 89.9 petajoules of energy. In a matter-antimatter annihilation reaction, the total energy released per gram of *antimatter* is twice this amount, making antimatter the most energy-dense substance known. However, this is a theoretical peak, with more practical sources also offering incredible power.

While fat provides the most energy of any dietary nutrient at 9 kcal per gram, this is dwarfed by nuclear power. But what truly releases the greatest amount of energy per gram? The answer lies far beyond dietary calories and even nuclear reactions, at the very limit of physical possibility.

In a closed system, the total amount of energy remains constant according to the law of conservation of energy. Understanding what does the total energy include is fundamental to physics, as it comprises the sum of all forms of energy present within that system.

At 9 calories per gram, fat is the most calorie-dense macronutrient humans can digest. But if you're asking what's the most calorie-dense object in the universe, the answer goes far beyond the dinner table and into the realm of theoretical physics.