this post was submitted on 08 Mar 2025
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Energy in physics feels analogous to money in economics. Is a manmade medium of exchange used for convenience. It is the exchange medium between measureable physical states/things.

Is energy is real in the same way money is? An incredibly useful accounting trick that is used so frequently it feels fundamental, but really it's just a mathmatical convenience?

Small aside: From this perspective 'conservatipn of energy' is a redundant statement. Of course energy must be conserved or else the equations are wrong. The definition of energy is it's conservation.

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[–] [email protected] 11 points 1 day ago* (last edited 1 day ago) (3 children)

I'm no expert, but I was an aerospace engineering student once upon a time. So here's my take:

Energy is not "manmade" because it would still exist and be transferred between systems even if humans didn't exist.

Stars would still burn. Gravity would still pull. Inertia would still inert. Accelerating mass would still require energy. There just wouldn't be anyone around to punch in numbers into a calculator and name the concept "energy".

Of course all math and physics are "manmade" insofar as they are theorized, discovered, and proven by humans. But these phenomena would still exist regardless of humanity. This feels analogous to asking if "electricity" is manmade. We discovered and named the physical concept; it doesn't mean we invented it. If a tree falls in the forest and no one is around to hear it, it still makes a sound.

[–] [email protected] 3 points 1 day ago

Inertia would still inert.

I must remember this.

I'm not lazy, i'm inerting.

[–] tomi000 1 points 1 day ago (1 children)

Electricity and sound are actual physical phenomena though, as in the arrangement or movement of atoms and electrons. Does energy have some sort of "matter"?

[–] [email protected] 3 points 22 hours ago

Electricity and sound are actual physical phenomena though

Those physical phenomena are the manifestation of the transfer of energy between systems. Electrons carry charge (a fundamental force, like gravity, which transfers energy through the system) through conduits and sound carries air pressure fluctuations (force per unit area, transferring energy through the system) through the air.

Does energy have some sort of “matter”?

Energy, in the mechanical sense, is "the ability to do work" (where work is defined as the ability to move a mass over a distance, i.e.: Force = Mass * Acceleration). The situations you described can be ultimately represented by fundamental physical principles like F=ma. Energy may be described as the medium through which matter interacts with other matter, but energy does not, itself, have matter. Though my academic background is more in the realm of mechanical physics; there may be some newfangled theoretical energy-mass superposition concept that I'm unaware of.

[–] [email protected] -4 points 1 day ago (2 children)

I was with you up until the last sentence. Molecules vibrate and pass some of that molecular vibration on to neighbouring molecules. It’s kinetic energy.

It only becomes sound when a listening device of some sort registers it (usually an ear, but could also be an insect leg, etc.).

[–] [email protected] 13 points 1 day ago (1 children)

It only becomes sound when a listening device of some sort registers it (usually an ear, but could also be an insect leg, etc.).

Acoustic waves propagating through a medium (air) exist regardless of whether or not something can perceive it as audio. I would argue that the mechanical phenomenon we call "sound" (acoustic waves) exists regardless of whether or not someone hears it. Similar to how light (electromagnetic radiation) exists regardless of if someone is around to look at it.

[–] [email protected] 3 points 1 day ago

That saying always seemed really stupid to me. Of course it makes a sound. Ugh

[–] [email protected] 6 points 1 day ago (1 children)

What we typically refer to as "sound" is the airwave, not the perception; at least in physics.

[–] [email protected] 2 points 20 hours ago (1 children)

Sound is just a pressure wave propogating through any compressible medium, right? Though I think we are a bit inconsistent in how we use it. E.g. Almost no one calls the seismic waves from an earthquake a "sound".

[–] [email protected] 2 points 18 hours ago

yeah, human language can be a bit inconsistent/imprecise at times. That is why all tech and engineering have their own language: maths; where consistent and precise descriptions are possible.