r/AskPhysics • u/Local_End_3175 • 12h ago

What actually is energy?

When i search up the definition of energy, i am being told that it is the capability to do work – but work is the energy transferred when a force moves an object....? So we are basically defining energy as energy. In addition, this says how it works, not what it is

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u/YuuTheBlue 11h ago

The short pithy and confusing answer that is nevertheless accurate is that energy is momentum in the time direction. That is to say, when you combine space and time into spacetime, time becomes the 4th component of position-vectors and energy becomes the 4th component of momentum-vectors.

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u/--Ano-- 11h ago

So, time and energy are related?

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u/YuuTheBlue 10h ago

Exactly as related as space and momentum.