Energy is work. We feel the energy with its heat. Energy is measured in Joules. The physical economy is also measured with work, with Joules. The work done by a human, or a robot, consumes energy. An atom is inert energy, not creating work outside a body, yet able to organize itself in our body, to help us work.
Energy is not fully understood. Indeed, NASA discovered that there were statistically more and more stars in the universe, including big ones, proving that the universe creates (...)