What is the reason behind why energy must always be conserved, apart from observation?
30883
Why can't energy be created or destroyed?
1031
When does Hamiltonian equals to energy of the system?
139061
Why is 7 TeV considered as a big amount of energy?
122524
Is energy conserved when things fall into a black hole?
69188
Why is conservation of angular momentum considered a law?
3471
Why does holding something up cost energy while no work is being done?
2073
Conservation law of energy and Big Bang?
107971
Hubble's law and conservation of energy
45669
What is behind the definitions of work and energy?
89301
Is the total energy of the universe constant?
86806
When you lift a box from the floor, the potential energy changes but kinetic energy does not change. Does it violate conservation of energy?
69799
Why, fundamentally, are particles charged?
142441
If rest mass does not change with $v$ then why is infinite energy required to accelerate an object to the speed of light?
2814
Energy conservation of Virtual Particles - Quantum Fluctuation?
83770
Kinetic energy doesn't make sense
120098
Work and Kinetic energy rely on each other which came first?
146039
Is it always possible to define energy of a system?