Now when an actual kiln cools down, it loses heat to its surroundings. No heat is destroyed. But the universe has no surroundings to which it can lose heat. For it to cool down, heat disappears, which means energy is not being conserved. But this is what Noether’s theorem predicts. In the early universe, the fabric of space and time were different than how they are now, and so the laws of mechanics, for example, were different than the way they are now. And that means in turn that energy is not conserved. In summary, Noether’s theorem predicts that energy is conserved only when space and time
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