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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If it can predict what will happen it is real
It’s as made up as time, but it’s as real as anything can be understood to be, with emphasis on ‘understood’. It doesn’t exist in actuality mostly because our words and models don’t describe it even close to well enough to consider the actual thing. It’s like a really poor translation of a word, it might get us closer to understanding what’s going on but will never be if your goal is to describe it to something like the human mind.
If a one-ton boulder rolls down an Earthly hill in my direction and I don’t move, what happens is not a manmade concept. Call it what you will.
Time on the other hand exists only as a useful mental tool to describe change. When I repeat the experiment of going to sleep, when I wake up it’s still always now. That experiment -always- produces the same result.
You can say that about all of math and science. It’s all language to describe observations of the universe.
What else are you going to do?
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.
That’s circular reasoning on your part. “The definition of energy is its conservation” is false so that’s not redundant. Don’t know where you got that from.
Things move and collide. Systems arrange themselves into patterns and come undone through disorder. The words we use to describe natural action exist indepenently of action itself. Momentum, symmetry, order, chaos, calculation. The words and definitions are made up, the phenomenon we attempt to encapsulate and abstractly represent is not.
The concept of energy is connected to its counterparts, the flow of physical mass and the abstract information contained within the flow or guiding it.
The various ways things act and paths followed to undergo change are what we attempt to understand through the theorems of math and symbolic physical laws of the universe. They are behind the fundamental layer-cake that is our reality.
Encoded in the patterns of a swinging pendulum, the electron cloud vibrating around atoms, the wavelength quanta and redshifting of photons, the nuclear fusion and fission of elements in stars.
Biological process of plant cell chloroplast, photon solar energy, carbon and water to churn sugar and protien. Dynamics of all living things based on complex calculative statistics relating food, resources, population size, and death rate.
Electrical whizzing of neurons that make up the computations of biological minds. Lakes of water floating above head forming the convection cycle. Virtual particles that pop into and out of existence in the smallest scales of existence at high fractions the speed of light.
Immense gravitational waves that emminate from two black holes merging their topologies. Infinitesimal gravitational pulls that relate you to the sun moon, planets, every comet, speck of dust, everything in the observable universe.
These are all real observable things that exist whether or not we attempt to describe or sense them. Energy and information are everywhere because they make up everything.
The curious thing about matter is that if you zoom in far enough, you’ll find that it is energy, and energy is basically vibrations and waves rippling.
The way it’s often described, if you zoom into a hydrogen atom, it’s mostly empty space, let’s say the proton is the size of a tennis ball, the electron is like a grain of sand a kilometer away.
But then zoom further in, inside the proton, and it’s made of three quarks. But those three quarks make up only 1% of the proton’s total mass! The other 99% is like a boiling and roiling little sea of all sorts of particles popping in and out of existence, such as gluons (which keep those three quarks bound tightly together), as well as more quarks, and other more exotic particles, some of them heavier than the proton itself! But they disappear almost at the same instant in which they are created. This is a constant, non-stop process, happening inside every proton and neutron in the universe.
And what do you call that virtual stuff that always keeps on popping in and out of existence between the three permanent (aka valance) quarks and makes up 99% of the proton’s mass? That’s energy.
Now zoom back out, and back in, towards the electron; what’s going on there? It’s a lone particle (also a wave, but let’s not get into that now), there is no 1% / 99% of something, all valance no virtual.
But nudge that particle towards its’ antimatter counterpart, the positron, and both particles dissolve into a flurry of photons that instantly fly away at the speed of light - pure energy. It’s as if their little charge shells (electron - negative, positron - positive) dissolve and a flash of pure energy comes out.
This also applies to quarks and their antiquark counterparts.That right there, is Einstein’s E=mc^2 in action, in all its’ glory. Energy equals mass.
Energy is something. It is there, even at the most fundamental and abstract level. It can be measured precisely, and explains so much so clearly, it’s incredible.
EDIT: fixed a sentence in the wrong place
Interesting, I thought energy is photons themselves. Or is energy a group of those particles that pop out, like what you mentioned. Or is it a side effect from those that pop out?
The matter does get converted into those photons.
Said another way:
The things go from being a couple of spin-half particles/antiparticles to a flurry of spin-one photons.Everything is energy. How big the energy is and how it moves is really all the difference between photons and mountains. Took a recent Veritasium video for that to really click for me.
Energy is not really manmade. It’s not a physical object, but that doesn’t mean that we invented it. It’s a pattern of behavior that we gave a name to. Whether we notice the pattern or not, the pattern is still there.
It’s the same as gravity - it’s not a physical object, it’s a pattern that describes how massive objects interact. But you wouldn’t argue that gravity doesn’t exist, would you?
On the risk of looking like a lunatic philosopher, yes, I’d argue that gravity doesn’t exist.
Even if energy is not manmade, the concept of energy is, or in other words: we invented this concept in order to more easily understand phenomena around us.
I see a lot of replies saying that “energy is in all things and is immutable”, but we (at least I) can imagine a scenario where someone invents a whole new system to describe nature which might not use the concept of energy at all (or any other concept you choose, such as gravity). The nature can be the same but the way we describe it can vary wildly (more likely beyond human comprehension).
It’s as I said - just because someone (or some species) doesn’t recognize this pattern, doesn’t mean the pattern doesn’t exist.
If some other alien race found a new system of physics that we were unaware of, that does not necessarily invalidate our laws of physics, just as ours would not invalidate theirs. Say, for example, in their system of physics, some arbitrary measurement that we’ll call “azupo” is equivalent to another measurement that we’ll call “bamu”, and this equation is called the “conservation of qugok”, that does not mean that qugok does not exist.
Clearly this equation is true (and therefore qugok is a real concept), otherwise the aliens wouldn’t be able to fly across the galaxy to meet with us humans. Is qugok an innate property of the universe? Most probably not, but we never claimed that qugok (or energy, for that matter) is innate. All this means is just that we never noticed the qugok pattern, and therefore we never gave a name to it. But the qugok pattern is and has always been real.
To put to bluntly: saying that something is arbitrary is not the same as saying that it doesn’t exist. We arbitrarily define the color red, but I hope you won’t argue that the color red doesn’t exist. (Even an alien who can’t see the color red would at least acknowledge that photons can have different wavelengths and that “human red” simply refers to that silly wavelength of light)
Yup, we are in agreement, though I might have missphrased my comments to imply that one shouldn’t believe in energy
To that end, there is a quote from Dumbledore on one of the Harry Potter films (don’t know which one) where he says: “of course this is in your head Harry, but does it make this less real?”
People have died from energy. So, no.
You could die from nuclear radiation, micro waves, electricity, heat. These are all energy.
All those things have energy, but they aren’t energy. For example, with microwaves the energy is proportional to the wavelength. Nuclear radiation comes in 4 forms, three of them are fast moving particles, one of them is photons. Energy allows us to say this light wave with a specific wavelength has the same amount of energy as this beta emission electron with a specific speed, mass, and charge.
People died from the interaction small wavelength photons imparting momentum on the atoms on their body, or fast moving particles colliding with the atoms in their body.
If someone fell off a building and died I don’t think anyone would say ‘energy did that’. The person died as a result of transferring a lot of kinetic energy to the ground though.
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.
Inertia would still inert.
I must remember this.
I’m not lazy, i’m inerting.
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”?
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.
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.).
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.
That saying always seemed really stupid to me. Of course it makes a sound. Ugh
What we typically refer to as “sound” is the airwave, not the perception; at least in physics.
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”.
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.
Yes it’s manmade concept because people are made from matter so they use energy as a matter representation ignoring everything else that doesn’t have matter. Looking at you SI. 1 Joule = 1 J = 1 kg⋅m2⋅s−2 is amount of work done when a force of one newton displaces a body through a distance of one metre in the direction of that force. So you can see you need a weight, a distance and a time. Given that in quantum world distance is infinite, time and weight is 0 it’s completly manmade product.
Surprisingly good question, i would say. “yes” and “no”
Yes, physics specifically looks out to find “conserved quantities” and then goes on to ascribe great value to them, so, in some sense, yes, energy is considered important because it is a conserved quantity.
Also, yes, there are different types of energy (mechanical energy, light energy, chemical energy), and summing them all up via “energy” is indeed a bit of an accounting trick. but it’s also a so fundamentally useful trick that we consider it “real”.
Also, different than money, there is no central bank that can cause an arbitrary amount and cause an enormous inflation overnight. Similar to wood or cereals, there just is a limited supply of it per year, and that’s what we can use. Physics makes the rules here.
Great write up.
Agreed, the money analogy breaks down when you bring in the cost fluctuation of a good. The whole purpose of energy is that the same conditions result in the same energy calculation.
many have answered that as a concept, it is made up. But it is arguably the most real (and important) thing in all of physics (or maybe action, which is also some function dependent on energy). the money comparison is fine, if we have different forms of denominations of money (currency notes (different amounts), gold coins, etc) we have different forms of energy quantas.
Here is a viewpoint to understand - almost everything acts in a way to minimise total system energy. this can be (almost) made valid all the time if you include some probablistic factors. (If we take thermodynamics (which is by definition study of dynamics of energy(and heat, which can be considered as some kind of raw energy), then we include entropy, which is basically finding how many ways can a particular energy can achieved.). This is not a very rigorous way to put it all, but basically all of physics basically works on energy. Forces are basically caused by some kind of gradient in energy.
I’m a layman, but it seems to me you’re conflating apples and oranges.
Money is a tool invented by humans. It only exists because we created it for our purposes. If humans never existed, money would likely not exist. And someday, money as we know it, will likely change.
Energy, on the other hand, is something that exists regardless of humans. It is a concept that does not change, regardless of how you describe it.
Thats actually what OPs question was about, and I would argue its not exactly like youre saying. Energy is a concept used by humans to categorise natural processes. Its more like saying “kilometers exist regardless of humans”. While technically true, nothing is “naturally” measured in kilometers and there woudnt really “be” a kilometer without humans.
I understand. But I would counter with kilometers is a unit of distance. Energy is not a unit of measure. For that we have other words, like watts and volts and many others.
Energy and distance do exist without humans. How we measure both is a human construct like you said.
Yes, like literally all physical quantities. That’s how physics works.
So, what would it be a medium of, then? I mean money is a medium of exchange. And by your logic, energy is a medium of ____ ???
Exchange
I guess we can’t answer OP’s question, then. That’s too unspecific. Something gets exchanged, true. Is that man-made? Likely false, but depends on what we’re talking about.
A medium of exchange for force.
A photon of a certain wavelength imparts a known force when colliding with an electron. That force propels the electron to a higher orbital.
And how does the “manmade” tie into that? Did we make the photons? Exert the force or did we do something that brought force into existence?
