# All physics in simplicity

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I have a question, born of necessity : I believe that simplicity should always be at the center of everything : complexity becomes a poison for intuition and truth, when it is a mental masturbation apt to feed the ego of scientists who do not seek universal truths, but elitist beliefs to feel superior regardless( or, simply, the need to feel important, which in itself is an understandable need, but not at the cost of truth and justice ); the ego must not be developed without putting truth, courage, justice, the critical and rebellious spirit, as its foundation; otherwise it will be moved by the need to lie, to omit, to adapt reality to his oasis of certainties that have never really been questioned (in their foundations), preferring the illusion of having done so, made possible precisely by the use of complexity and dogma passed off as science;

complexity, yes, but when it is really necessary, without ever losing sight of simplicity; but perhaps, since complexity is also, from a certain point of view, relative to the ability to know how to handle it, then it is better to say that simplicity is that something you can most easily relate to those things that communicate universally, practically all the time, while complexity is something that moves away from that, but still DERIVES from that, from simplicity, and is not something disjointed from it.

From simplicity to complexity, via modularity, which is still a way of managing with the measure of simplicity, complexity

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Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a system into varying degrees of interdependence and independence across and "hide the complexity of each part behind an abstraction and interface".

I am a firm believer in the following statement, "You haven't really understood something until you are able to explain it to a five-year-old" ( or "You haven't really understood something until you are able to explain it to your grandmother." : in this statement there is a universal truth that should, must, permeate everything; what strays from this assertion, strays from truth, and therefore, from justice.

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( July 2014 )
https://physicstoday.scitation.org/doi/10.1063/PT.3.2448
A more fundamental International System of Units
The universally accepted method of expressing physical measurements for world commerce, industry, and science is about to get a facelift, thanks to our improved knowledge of fundamental constants.

However, international consensus is building to once again advance the SI to reflect contemporary understanding of the physical world. The new framework of the future SI will no longer define seven base units and coherently derived units; instead, it will adopt exact values for seven fundamental constants of nature on which all SI units will be realized. Gone are the base units and their definitions.

The new SI will also have seven base quantities: frequency, velocity, action, electric charge, heat capacity, amount of substance, and luminous intensity.

As can be seen in tables I and II, the present and future definitions of the SI have similarities, especially when one compares the present base quantities of time and length with the new base quantities of frequency and velocity. The definitions are fully equivalent, as is also the case for luminous intensity. That equivalence is because the present SI has already incorporated invariants of nature as part of its foundation, thanks to the 1967 and 1983 redefinitions of the second and meter, respectively.

Because the SI has been continually evolving with new knowledge and technological advances, (...)

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( May 2019 )
The New International System of Units (SI): Quantum Metrology and Quantum Standards
https://www.wiley.com/en-us/The+New+International+System+of+Units+(SI)%3A+Quantum+Metrology+and+Quantum+Standards-p-9783527814497

we get into the specifics, with the five Ws ( https://en.wikipedia.org/wiki/Five_Ws ), on those units of measurement.

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https://en.wikipedia.org/wiki/International_System_of_Units
Unit name: ampere
Unit symbol: A
Dimension symbol: I
Quantity name: electric current
Typical symbols: I, i
Definition: "The flow of exactly 1 / 1.602176634×10^−19 times the elementary charge *e* per second.
Equalling approximately 6.2415090744×1018 elementary charges per second."

However, the definition of ampere seems to me to be more of a derived quantity/units of measure than a fundamental quantity/units of measure;

And in fact here
https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units
it is stated that the new definition of 2019 is more 'fundamental', than the previous one ( although it is also said that "A consequence of the revised definition is that the ampere no longer depends on the definitions of the kilogram and the metre; it does, however, still depend on the definition of the second." )

and so on.

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https://www.kpphysics.com/fundamental-quantities/
Seven physical quantities have been chosen as fondamental or base quantities these are length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity"

"have been chosen"

Are there actually only seven, of these physical quantities/units of measure, or is there an arbitrary choice, and would there also be more, perhaps not considered for certain, or indeterminate, reasons ?

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Now, on this premise, I ask you : is there a searchable source for study where the whole ( or almost ) physics is ALL expressed in terms of only fundamental quantities/units of measure, thus without the use of derived quantities/units of measure ?

Derived quantities/units of measure have their utility, certainly; but My request is also an epistemological and gnoseological experiment;

to always express everything, whenever possible ( is it always possible ? ), in terms of only fundamental quantities/units of measure, I feel this as a security on the side of truth, thus of knowledge that is going to expand with research; and where it might seem that it is not possible to apply such a principle, it must be shown why, with empirical experiments attesting that something more must be added, of 'only' fundamental quantities, in order to be able to continue with research; essentially, simplicity is thus the guarantee of not ending up in blind alleys without realizing it, dazzled by unnecessary complexity.

Fundamental quantities/units of measure are a function of what ? Of our senses; the measuring instruments built by the Human Being, flow from the awareness one has, of one's senses ( and I mean these : https://www.hellahealth.com/blog/wellness/humans-five-senses/ , https://bigthink.com/surprising-science/think-you-have-only-5-senses-its-actually-a-lot-more-than-that/ , and many more ). It might seem a limitation, but the Human Being is meter and measure for the whole of creation, someone would say ( and I agree )

Thank you.

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1 hour ago, Dialogos said:

is there a searchable source for study where the whole ( or almost ) physics is ALL expressed in terms of only fundamental quantities/units of measure, thus without the use of derived quantities/units of measure ?

Which units are fundamental, and which are derived, is a matter of convenience. There is nothing fundamental in this choice.

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Posted (edited)
3 hours ago, Dialogos said:

I have a question, born of necessity : I believe that simplicity should always be at the center of everything : complexity becomes a poison for intuition and truth, when it is a mental masturbation apt to feed the ego of scientists who do not seek universal truths, but elitist beliefs to feel superior regardless( or, simply, the need to feel important, which in itself is an understandable need, but not at the cost of truth and justice ); the ego must not be developed without putting truth, courage, justice, the critical and rebellious spirit, as its foundation; otherwise it will be moved by the need to lie, to omit, to adapt reality to his oasis of certainties that have never really been questioned (in their foundations), preferring the illusion of having done so, made possible precisely by the use of complexity and dogma passed off as science;

complexity, yes, but when it is really necessary, without ever losing sight of simplicity; but perhaps, since complexity is also, from a certain point of view, relative to the ability to know how to handle it, then it is better to say that simplicity is that something you can most easily relate to those things that communicate universally, practically all the time, while complexity is something that moves away from that, but still DERIVES from that, from simplicity, and is not something disjointed from it.

From simplicity to complexity, via modularity, which is still a way of managing with the measure of simplicity, complexity

Good morning.

I am in two minds as to whether to bother with this thread, given your opening preconditions.

My first reaction was

Where is the Physics in all this ?

However your actual question is more reasonable.

So perhaps you might like to replace that opening leg-iron with some useful context.

For instance, at what level ae you seeking this system ?

Sub-atomic particle level.

Or macroscopic atomic physics and above?

Although there is some small ovelap, fundamental units in these realms are mostly quite different.

For instance you mentioned the Ampere, which has no meaning at sub atomic level.

Further when you say units, how are you relating these to the well described 'method of dimensions', used throughout science and engineering ?

Edited by studiot
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I disagree with most of the opening post. Hobbling yourself with so many absolute beliefs (simplicity = good, complexity = bad) is not being objective enough for science. There's no reason why physics has to conform to our concepts of neatness and symmetry.

I've never understood why some people demand that the universe be intuitive and simple, when we know it's definitely not. And as far as being able to explain QM to a five-year-old, I think that's just a platitude that seems more reasonable than it is. Some areas of science require more sophistication, or knowledge from multiple disciplines studied in tandem. I think "dumbing it down" for laypeople/children has caused a LOT of problems with understanding (dare I bring up the "fabric" of space popular explanation for gravity again?).

In actual practice, demanding explanations simple enough for a child runs counter to our best methodologies. It's a cognitive bias if you're only looking for things you can explain to a child. Clouds must weigh next to nothing if they can float up so high in the air like that, right?

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9 hours ago, Dialogos said:

to feed the ego of scientists who do not seek universal truths, but elitist beliefs to feel superior regardless( or, simply, the need to feel important

Spoken like a person who did not see the value of investing time and effort to learn some Physics.
Which then brings us to your second question ...

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9 hours ago, Dialogos said:

I have a question, born of necessity : I believe that simplicity should always be at the center of everything : complexity becomes a poison for intuition and truth, when it is a mental masturbation apt to feed the ego of scientists who do not seek universal truths, but elitist beliefs to feel superior regardless( or, simply, the need to feel important, which in itself is an understandable need, but not at the cost of truth and justice ); the ego must not be developed without putting truth, courage, justice, the critical and rebellious spirit, as its foundation; otherwise it will be moved by the need to lie, to omit, to adapt reality to his oasis of certainties that have never really been questioned (in their foundations), preferring the illusion of having done so, made possible precisely by the use of complexity and dogma passed off as science;

complexity, yes, but when it is really necessary, without ever losing sight of simplicity; but perhaps, since complexity is also, from a certain point of view, relative to the ability to know how to handle it, then it is better to say that simplicity is that something you can most easily relate to those things that communicate universally, practically all the time, while complexity is something that moves away from that, but still DERIVES from that, from simplicity, and is not something disjointed from it.

From simplicity to complexity, via modularity, which is still a way of managing with the measure of simplicity, complexity

I am a firm believer in the following statement, "You haven't really understood something until you are able to explain it to a five-year-old" ( or "You haven't really understood something until you are able to explain it to your grandmother." : in this statement there is a universal truth that should, must, permeate everything; what strays from this assertion, strays from truth, and therefore, from justice.

---

Here

---

Here

we get into the specifics, with the five Ws ( https://en.wikipedia.org/wiki/Five_Ws ), on those units of measurement.

---
Here

However, the definition of ampere seems to me to be more of a derived quantity/units of measure than a fundamental quantity/units of measure;

And in fact here
https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units
it is stated that the new definition of 2019 is more 'fundamental', than the previous one ( although it is also said that "A consequence of the revised definition is that the ampere no longer depends on the definitions of the kilogram and the metre; it does, however, still depend on the definition of the second." )

and so on.

---

Here

"have been chosen"

Are there actually only seven, of these physical quantities/units of measure, or is there an arbitrary choice, and would there also be more, perhaps not considered for certain, or indeterminate, reasons ?

---

Now, on this premise, I ask you : is there a searchable source for study where the whole ( or almost ) physics is ALL expressed in terms of only fundamental quantities/units of measure, thus without the use of derived quantities/units of measure ?

Derived quantities/units of measure have their utility, certainly; but My request is also an epistemological and gnoseological experiment;

to always express everything, whenever possible ( is it always possible ? ), in terms of only fundamental quantities/units of measure, I feel this as a security on the side of truth, thus of knowledge that is going to expand with research; and where it might seem that it is not possible to apply such a principle, it must be shown why, with empirical experiments attesting that something more must be added, of 'only' fundamental quantities, in order to be able to continue with research; essentially, simplicity is thus the guarantee of not ending up in blind alleys without realizing it, dazzled by unnecessary complexity.

Fundamental quantities/units of measure are a function of what ? Of our senses; the measuring instruments built by the Human Being, flow from the awareness one has, of one's senses ( and I mean these : https://www.hellahealth.com/blog/wellness/humans-five-senses/ , https://bigthink.com/surprising-science/think-you-have-only-5-senses-its-actually-a-lot-more-than-that/ , and many more ). It might seem a limitation, but the Human Being is meter and measure for the whole of creation, someone would say ( and I agree )

Thank you.

This reads like the complaint of someone that does not understand a subject and decides to attack those who do instead of getting the books out and bothering to learn.

Choice of units is basically irrelevant to the complexity or otherwise of physics. Such complexity as it has is the result of applying Ockham's Razor. This does NOT, as some people fondly imagine, argue for simplicity above all else, but for no more complexity than is necessary to fit the facts. So, to the extent physical science is complex, it is because that's what observing nature tells us it is like. You can't wish it away just because of your lack of understanding.

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More wishful thinking...

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15 hours ago, Dialogos said:

Are there actually only seven, of these physical quantities/units of measure, or is there an arbitrary choice, and would there also be more, perhaps not considered for certain, or indeterminate, reasons ?

It’s not arbitrary, in the they are determined by the independent quantities in physics - length, mass, time, etc. can’t be expressed in terms of each other at a fundamental level. But the issue of current vs charge, for example, tells us that there are choices.

15 hours ago, Dialogos said:

Now, on this premise, I ask you : is there a searchable source for study where the whole ( or almost ) physics is ALL expressed in terms of only fundamental quantities/units of measure, thus without the use of derived quantities/units of measure ?

Probably not. Derived units are used for convenience, and anyone can go through the exercise of breaking them down.

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23 hours ago, Dialogos said:

I am a firm believer in the following statement, "You haven't really understood something until you are able to explain it to a five-year-old" ( or "You haven't really understood something until you are able to explain it to your grandmother." : in this statement there is a universal truth that should, must, permeate everything; what strays from this assertion, strays from truth, and therefore, from justice.

I think this statement is both false and ultimately meaningless. First of all, the distinction between “simple” and “complex” is not objective, but very much contextual - what’s simple to me might be complex for you, and vice versa. It depends on our respective backgrounds. Secondly, even if the distinction was objective, the statement that you haven’t really understood something unless you can explain it to your child/grandmother etc is clearly misleading - it was never meant to be taken this literally.

In my native language, we have a reasonably complicated system of declining nouns and conjugating verbs - according to grammatical case, gender, number, aspect, conditionality, tense etc etc we add prefixes, suffixes, prepositions and postpositions, and sometimes we change the middle part of the word as well, depending on what type of word it is and how it is used. There is also a large number of personal pronouns, never even mind all the irregular verbs, plural forms and so on. There is no way I could quickly and easily explain these things to someone who comes from a different language background, irrespective of what age they are, because some of the basic concepts (e.g. grammatical gender of nouns, or explicit declination by case) simply may not exist in other languages. Of course anyone can - at least in principle - learn the language, but it is generally going to take years of study and practice (unless you are lucky enough to have a mother tongue that is closely related), and not so many foreigners ever become completely fluent in it. It’s just a grammatically complex language, to the extent that even native speakers occasionally have trouble with complex grammatical structures. Does my inability to easily explain these things mean I do not understand the concepts of my native language? Of course not - I understand them perfectly well, to the extent that they are intuitive and self-evident to me. But that doesn’t mean I can easily explain to someone from a different linguistic background why “girl” should be of neutral gender, or why the “me” in “give me it”<>”give it to me” requires different pronouns. Some of these things don’t evenhave explanations, they are just conventions that have organically grown over time, so they have to be acquired, not understood.

It’s no different in science - e.g. I understand the concepts of differentiation and integration well enough, I consider these basic operations just like addition and subtraction. But could I explain them to a 5-year old, who has no concept of curves, functions, variables, tangents, limits etc etc, in a way that he’ll actually end up understanding it all? Probably not, unless I’m dealing with an unusually gifted child. But my inability to explain does not mean that I don’t understand, it just means that the child doesn’t have the necessary prerequisites yet to benefit from my explanations. Crucially, my inability to explain it also doesn’t mean that the 5-year old cannot acquire this understanding over time - if you teach him the requisite concepts, there’s no reason why he couldn’t understand differentiation and integration once he’s a bit older. You just start with the basics, and then build onto them. That’s how people acquire new skills.

On 3/17/2023 at 10:20 AM, Dialogos said:

Now, on this premise, I ask you : is there a searchable source for study where the whole ( or almost ) physics is ALL expressed in terms of only fundamental quantities/units of measure, thus without the use of derived quantities/units of measure ?

How do you define “fundamental” and “derived”?

To me, the most fundamental and most broadly-applicable principle, which underlies a guess-timated 70% or so of all know physics from the Standard Model right up to General Relativity, is the principle of extremal action:

$\delta S=0$

This statement is as simple in form and function as it is powerful, and as close to a “theory of everything” as we have at this point in time. It also does not rely on any particular choice of units or spacetime embedding. To me this is pretty much the bedrock of much of currently known physics, though my feeling is that you probably wouldn’t consider it “fundamental”.

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The previous comment brought to mind another linguistic example of subjectivity of a judgement regarding simplicity vs complexity, namely vowels in Hebrew, or rather a lack of them. Is writing without vowels simpler or more complex than otherwise? It certainly makes texts shorter and leaves fewer possibilities to make mistakes. In fact, the vowels are not used because it turned out that they are not needed, in Hebrew. The way the language works, they can be determined by the context.

OTOH, I had a discussion once with a new immigrant in Israel who believed that Israelis don't use vowels on purpose, i.e., to make learning the language more difficult for new immigrants in order to reduce their abilities to compete for jobs. This is not unlike the complaints in OP.

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namely vowels in Hebrew, or rather a lack of them

Something similar happens in written Thai as well, though to a much more limited extent - there’s specifically two short vowels that are not always written, but implied. That actually caused me a lot of grief when I first started learning.

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The previous comment brought to mind another linguistic example of subjectivity of a judgement regarding simplicity vs complexity, namely vowels in Hebrew, or rather a lack of them. Is writing without vowels simpler or more complex than otherwise? It certainly makes texts shorter and leaves fewer possibilities to make mistakes. In fact, the vowels are not used because it turned out that they are not needed, in Hebrew. The way the language works, they can be determined by the context.

OTOH, I had a discussion once with a new immigrant in Israel who believed that Israelis don't use vowels on purpose, i.e., to make learning the language more difficult for new immigrants in order to reduce their abilities to compete for jobs. This is not unlike the complaints in OP.

The same is true of written Arabic, at least for some vowels, presumably owing to their common root.

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On 3/18/2023 at 10:37 AM, Markus Hanke said:

I think this statement is both false and ultimately meaningless. First of all, the distinction between “simple” and “complex” is not objective, but very much contextual - what’s simple to me might be complex for you, and vice versa. It depends on our respective backgrounds. Secondly, even if the distinction was objective, the statement that you haven’t really understood something unless you can explain it to your child/grandmother etc is clearly misleading - it was never meant to be taken this literally.

In my native language, we have a reasonably complicated system of declining nouns and conjugating verbs - according to grammatical case, gender, number, aspect, conditionality, tense etc etc we add prefixes, suffixes, prepositions and postpositions, and sometimes we change the middle part of the word as well, depending on what type of word it is and how it is used. There is also a large number of personal pronouns, never even mind all the irregular verbs, plural forms and so on. There is no way I could quickly and easily explain these things to someone who comes from a different language background, irrespective of what age they are, because some of the basic concepts (e.g. grammatical gender of nouns, or explicit declination by case) simply may not exist in other languages. Of course anyone can - at least in principle - learn the language, but it is generally going to take years of study and practice (unless you are lucky enough to have a mother tongue that is closely related), and not so many foreigners ever become completely fluent in it. It’s just a grammatically complex language, to the extent that even native speakers occasionally have trouble with complex grammatical structures. Does my inability to easily explain these things mean I do not understand the concepts of my native language? Of course not - I understand them perfectly well, to the extent that they are intuitive and self-evident to me. But that doesn’t mean I can easily explain to someone from a different linguistic background why “girl” should be of neutral gender, or why the “me” in “give me it”<>”give it to me” requires different pronouns. Some of these things don’t evenhave explanations, they are just conventions that have organically grown over time, so they have to be acquired, not understood.

It’s no different in science - e.g. I understand the concepts of differentiation and integration well enough, I consider these basic operations just like addition and subtraction. But could I explain them to a 5-year old, who has no concept of curves, functions, variables, tangents, limits etc etc, in a way that he’ll actually end up understanding it all? Probably not, unless I’m dealing with an unusually gifted child. But my inability to explain does not mean that I don’t understand, it just means that the child doesn’t have the necessary prerequisites yet to benefit from my explanations. Crucially, my inability to explain it also doesn’t mean that the 5-year old cannot acquire this understanding over time - if you teach him the requisite concepts, there’s no reason why he couldn’t understand differentiation and integration once he’s a bit older. You just start with the basics, and then build onto them. That’s how people acquire new skills.

How do you define “fundamental” and “derived”?

To me, the most fundamental and most broadly-applicable principle, which underlies a guess-timated 70% or so of all know physics from the Standard Model right up to General Relativity, is the principle of extremal action:

δS=0

This statement is as simple in form and function as it is powerful, and as close to a “theory of everything” as we have at this point in time. It also does not rely on any particular choice of units or spacetime embedding. To me this is pretty much the bedrock of much of currently known physics, though my feeling is that you probably wouldn’t consider it “fundamental”.

This made me think of Feynman's comment on "unworldliness" and the 'beautiful' equation U=0,

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Let us show you something interesting that we have recently discovered: All of the laws of physics can be contained in one equation. That equation is

U=(eq. 25.30)

What a simple equation! Of course, it is necessary to know what the symbol means. U is a physical quantity which we will call the “unworldliness” of the situation.

[...]

This “law” means, of course, that the sum of the squares of all the individual mismatches is zero, and the only way the sum of a lot of squares can be zero is for each one of the terms to be zero.

So the “beautifully simple” law in Eq. (25.32) is equivalent to the whole series of equations that you originally wrote down. It is therefore absolutely obvious that a simple notation that just hides the complexity in the definitions of symbols is not real simplicity. It is just a trick. The beauty that appears in Eq. (25.32)—just from the fact that several equations are hidden within it—is no more than a trick. When you unwrap the whole thing, you get back where you were before.

By the way, I think the OP is using a word, "complexity" --that has a very specific meaning in physics and other sciences very intimately connected to it-- to mean something better captured by "difficult", "cumbersome", "steep learning curve", etc.

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54 minutes ago, joigus said:

This made me think of Feynman's comment on "unworldliness" and the 'beautiful' equation U=0,

By the way, I think the OP is using a word, "complexity" --that has a very specific meaning in physics and other sciences very intimately connected to it-- to mean something better captured by "difficult", "cumbersome", "steep learning curve", etc.

..or even "that which I don't understand".

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29 minutes ago, exchemist said:

..or even "that which I don't understand".

Yes. When physicists talk about simplicity, what they mean is most phenomena --perhaps all-- can be understood in terms of very simple principles. It's the constant overarching theme of a swathe of apparently different phenomena boiling down to very simple principles. The devil, of course, is in the details. And the very sophisticated formalism one has to learn first --and here's where the steep learning curve comes in--, in order to see how beautifully simple and economic the abstract formulation is.

Thus, one could say chemistry is basically about exchange of electrons (red-ox) and protons (acid-base); physics is about minimising the action. We all know it's "just" about this. And as to geology and biology...

Bad example. Biology and geology are genuinely complex. Complex in every sense.

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