Exactly 200 years ago, a French engineer introduced an idea that would quantify the universe’s inexorable slide into decay. But entropy, as it’s currently understood, is less a fact about the world ...

Though a cornerstone of thermodynamics, entropy remains one of the most vexing concepts to teach budding physicists in the classroom. Physics teachers designed a hand-held model to demonstrate the ...

Compressing hydrogen demands high pressures; liquefying it requires extreme cooling. Both approaches carry energy penalties, safety considerations, and infrastructure costs that limit wider adoption.