Some ancient cultures say the universe is made out of energy. How did they understand the concept of energy without electricity? Or is this an assumption by modern historians injecting their modern knowledge onto ancient beliefs?

by Chicano_Ducky

For example, a Hopi women mentioned to me a web of energy in their ancient belief system.

Polynesia has the concept of Mana.

Similarly, Mesoamerican theology from books like Aztec philosphy: Understanding a world in motion says that the world is made out of Teotl, a kind of energy originating from a god.

Did ancient cultures even understand the concept of energy the way we do now? How are these ideas so wide spread that even disconnected cultures know of it throughout multiple eras?

rocketsocks

Words have layers of meaning, in some sense they are multiplicities of words with the same spelling and sound and so forth. There are more than a dozen different definitions for "run", for example. One could imagine a more formal version of speech where people explicitly separated these specific meanings and called them out in usage (with numbers, for example), so one might say "I would like to go for a run(1)". But, of course, this is very much not the way humans use language, nor the way we like to use it. This is mostly fine, and even has some beneficial side effects, in colloquial usage, but can become problematic in a scientific (or technical) context when greater precision is required.

Scientists are like everyone else, when they run across a new concept or model (or redefine an old one) they frequently just borrow an existing word and tack on another additional definition to it. The word "energy", of course, was not invented by scientists, it existed long before scientific work in the fields of kinematics or thermodynamics (let alone quantum mechanics) and was pressed into service by them. In that use it has a very specific and exacting definition aside from the broader colloquial definition.

And, of course, there are many common words that modern science has laid claim to which exist as terms in a great many languages (even in ancient times): energy, mass, momentum, gravity, particle, light, etc. "Mass" for example has a very specific definition in modern science based on the theory of general relativity which is just one definition among many for the word.

No ancient peoples had a full understanding of the scientific definition of energy as we understand it today, but then again not even scientists in, say, 1850 or even 1900 did either. The relatedness of the definitions of fundamental concepts throughout time is a subject that could be (and has been and will be) debated endlessly with plenty of arguments every which way. On the one hand Teotl, for example, is not "energy" as we know it, but is it close enough or is it evocative enough within a context of a "less sophisticated" understanding of physics to lay claim to some of the same territory even so?

There is an ocean of metaphysics and semantics there that one could sail and plumb forever (or drown in), but I'll try to stick to just the shallows here. "Energy" even in modern colloquial usage often has some aspect of association with life and specifically with human life and often with the concept of some animating force. It is, of course, a well known phenomenon that a living human or a living animal is "animated", they move, they breathe, they act, all of which are associated with the concept of (and indeed definition of the word) "energy". It is also well observed that these "energetic" qualities pass away upon death, a person or an animal becomes "lifeless", static instead of dynamic, inert instead of active, etc, in essence "de-energized". These things are very much a part of the common definition of the words for "energy" in almost every language, but this is where there is a strong divergence with the modern scientific definition of energy.

This very much gets to the heart of the difference between what has become the scientific understanding of the Universe (and of life and indeed even human beings) through mechanistic models. The fundamental forces of the Universe are understood to be mechanical, and things like humans or animals are simply advanced "mechanical" systems while life and even consciousness are emergent properties of those systems. And when, say, a human consciousness is extinguished due to the brain or body that hosts it ceasing to operate this is simply an emergent property going away, not something fundamental at the lowest levels of the laws of physics changing. "Energy" in this scientific definition doesn't substantially change when a consciousness ceases, the stored chemical energy, the rest-energy of the sub-atomic particles, etc, etc, etc, these things continue. In contrast, the colloquial and ancient definition of "energy" (an animating spirit, for example) is lost upon death, and this usually ties in with a belief of consciousness and thought as not an emergent property of mechanical systems but instead as a fundamental, foundational aspect of the fabric of the Universe. This is the basic dividing line between "spiritual" concepts of the Universe and mechanical, "scientific" concepts. And for that reason I would personally say that origin stories from ancient peoples that talk about the importance of "energy" in the creation of the Universe but do so in a spiritual sense rather than a mechanistic one are not really "speaking the same language" or talking about the same things as in modern science, although sometimes the connections at a poetic or evocative level might be interesting or heart warming aside from any issues of accuracy.