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Energy can be described in many contexts, such as the energy required to move something - be it translational or rotational - being kinetic energy, temperature/heat, electricity, light, etc. However, many energies learned of at a young age are simply multiple forms of a single energy. That is, heat and movement are the same thing, the former being movement on a micro scale, the latter being on a macro scale. Similarly, electricity is, to my understanding, due to the movement of electrons, and light is the movement of photons.

As an aside, primarily to add details I've yet to properly organize, there are a number of thoughts I've considered. For one, we consider energy as measured in Joules. The formula for kinetic energy ($K = 1/2mv^2$) is mathematically the integral of momentum with respect to velocity ($p = mv$). This implies to me that energy is directly related to momentum, which relates mass to motion. However, light is considered to be massless, yet has energy. Specifically, I read somewhere in my searches on the topic that light, though massless, will add to the effective mass of a container. But my considerations would be that either 1) light does have mass, but simply the smallest possible mass, or 2) light is not adding to effective mass, but rather "applying force". My searches have indicated that light does transfer momentum, but to my basic knowledge momentum measures mass and speed, which would imply that the former (light having mass) would need to be true. Perhaps the energy of light is proportional to its frequency, given gamma rays are, to my knowledge, more energetic than radio waves, and the electrons of a chemical give off different colored photons based on the degree of energy state changed. On a separate note, I've found mention that the curvature of spacetime due to matter will cause objects to accrue motion, as even if the object technically isn't moving, the spacetime is.

All this to say, it would seem reasonable to me to say that all energy is simply some form of motion, be it the motion of an elementary particle, or motion of atoms on a micro scale, or motion of objects on a macro scale. However, it seems possible that there are nuances I'm not considering or otherwise am unaware of that would indicate that energy is its own factor separate from mass and spacetime rather than a combination of the two.

Simply, is energy equivalent to the motion of matter and subsequent transference of that motion, or is that not the case, and if so why?

Iter
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Simply, is energy equivalent to the motion of matter and subsequent transference of that motion?

Not quite - anything that has motion (massless or not) has energy inherent in that motion, but not anything that has energy has motion.

Quite simply, there's tons of energy you encounter every day that is not stored in motion: Batteries, fat cells, gasoline, oil, nuclear reactors, etc.

But my considerations would be that either 1) light does have mass, but simply the smallest possible mass, or 2) light is not adding to effective mass, but rather "applying force".

Light doesn't have mass. It does have momentum. The relativistic formula for momentum is $p=\gamma mv$; $\gamma = \infty, m = 0 $ so you can't use it for light as its undefined.

One interesting facet to consider, however - The rest mass of the quarks that make up a proton is only 3% of the total mass of the proton - the rest comes from the QCD binding energy of the quarks. The same concept governs how light adds to the mass of the container it's in.

Señor O
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My point of view is primarily from the classical application of kinematics and dynamics to the design of machines. This may be unsatisfying but three topics I can think of that need to be sorted out: [1] relativity (general and special), [2] the principle of inertia, [3] 1st & 2nd laws of thermodynamics. Each of these topics puts limitations on particles or systems of particles whether open or closed. Studying these limitations may provide more insight into the question of whether energy is ultimately related to motion. Perpetual motion machines have not been discovered for good reason. Achieving velocities greater than the speed of light remains elusive for good reason. You ask a good question.