After years of studying physics I am suddenly struck by the question - What is energy? Wikipedia defines it thus:

Energy is often understood as the ability a physical system has to do work on other physical systems. (1)

If that is the case, what is work?

In physics, work is the amount of energy transferred by a force acting through a distance in the direction of the force.(1)

Isn't this a cyclic argument? Energy is explained based on work is explained in terms of energy.

Again, in the second definition, what is force?

In physics, a force is any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape. (1)

Has anyone ever seen force, touched it, tasted it, dissected it etc? Sure, we say we know the effect of force - but does anyone really know what force itself is? A similar argument can apply to energy & work as well, does anyone know what they are?

This type of definition seems to me, as baseless as the statement - "God is the cause due to which the universe exists."

Some argue that we have an intuitive understanding of concepts such as energy,force etc & that no definition or verification is necessary but then again, many clerics also justify faith in God using a similar argument - that God exists & that no verification or definition is necessary or possible.

The foundations of Physics seem to be as feeble as those of Religion. Can anyone help me?


@Michael Dorfman Thanks for the great answer and also the reference to Richard Feynman. I looked up The Feynman Lectures & found the following extract very relevant to this question. I think it'll greatly enhance the quality this post.

What is Energy?

In this chapter, we begin our more detailed study of the different aspects of physics, having finished our description of things in general. To illustrate the ideas and the kind of reasoning that might be used in theoretical physics, we shall now examine one of the most basic laws of physics, the conservation of energy. There is a fact, or if you wish, a law, governing all natural phenomena that are known to date. There is no known exception to this law—it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call energy, that does not change in the manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says that there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or any- thing concrete; it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same. (Something like the bishop on a red square, and after a number of moves—details unknown—it is still on some red square. It is a law of this nature.) Since it is an abstract idea, we shall illustrate the meaning of it by an analogy. Imagine a child, perhaps "Dennis the Menace," who has blocks which are absolutely indestructible, and cannot be divided into pieces. Each is the same as the other. Let us suppose that he has 28 blocks. His mother puts him with his 28 blocks into a room at the beginning of the day. At the end of the day, being curious, she counts the blocks very carefully, and discovers a phenomenal law— no matter what he does with the blocks, there are always 28 remaining! This continues for a number of days, until one day there are only 27 blocks, but a little investigating shows that there is one under the rug—she must look everywhere to be sure that the number of blocks has not changed. One day, however, the number appears to change—there are only 26 blocks. Careful investigation in- dicates that the window was open, and upon looking outside, the other two blocks are found. Another day, careful count indicates that there are 30 blocks! This causes considerable consternation, until it is realized that Bruce came to visit, bringing his blocks with him, and he left a few at Dennis' house. After she has disposed of the extra blocks, she closes the window, does not let Bruce in, and then everything is going along all right, until one time she counts and finds only 25 blocks. However, there is a box in the room, a toy box, and the mother goes to open the toy box, but the boy says "No, do not open my toy box," and screams. Mother is not allowed to open the toy box. Being extremely curious, and somewhat ingenious, she invents a scheme! She knows that a block weighs three ounces, so she weighs the box at a time when she sees 28 blocks, and it weighs 16 ounces. The next time she wishes to check, she weighs the box again, subtracts sixteen ounces and divides by three. She discovers the following: Equation 4.1 There then appear to be some new deviations, but careful study indicates that the dirty water in the bathtub is changing its level. The child is throwing blocks into the water, and she cannot see them because it is so dirty, but she can find out how many blocks are in the water by adding another term to her formula. Since the original height of the water was 6 inches and each block raises the water a quarter of an inch, this new formula would be: Equation 4.2 In the gradual increase in the complexity of her world, she finds a whole series of terms representing ways of calculating how many blocks are in places where she is not allowed to look. As a result, she finds a complex formula, a quantity which has to be computed, which always stays the same in her situation. What is the analogy of this to the conservation of energy? The most re- markable aspect that must be abstracted from this picture is that there are no blocks. Take away the first terms in (4.1) and (4.2) and we find ourselves calculating more or less abstract things. The analogy has the following points. First, when we are calculating the energy, sometimes some of it leaves the system and goes away, or sometimes some comes in. In order to verify the conservation of energy, we must be careful that we have not put any in or taken any out. Second, the energy has a large number of different forms, and there is a formula for each one. These are: gravitational energy, kinetic energy, heat energy, elastic energy, electrical energy, chemical energy, radiant energy, nuclear energy, mass energy. If we total up the formulas for each of these contributions, it will not change except for energy going in and out. It is important to realize that in physics today, we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. However, there are formulas for calculating some numerical quantity, and when we add it all together it gives "28"'—always the same number. It is an abstract thing in that it does not tell us the mechanism or the reasons for the various formulas.

Source: The Feynman Lectures on Physics, Vol 1, Chapter 4: Conservation of Energy

(1) Wikipedia

  • 6
    You are perfectly right. Energy ('mass is energy') and force (as with magnetic or gravitational forces) concepts are 'magical' stuff in physics; we use them, calculate them, predict them, without really understanding them but only with the illusion that we grasp them (as opposed with the deep understanding we have with the wind force which makes the sailing ship move). Anyway, in my opinion, your question, which is a good one, does not follow ideally from your argumentation. Commented Aug 29, 2011 at 13:01
  • Glad you found the Feynman reference! That was definitely the passage I Was thinking of, but I wasn't completely sure where I had read it. Commented Sep 6, 2011 at 6:29
  • If you start with Newton's laws, in particular the second law, F = ma, and the third law, every force has an equal and opposite reaction force, then it is possible to deduce that the quantity 0.5mv^2 is constant. Therefore the conservation of this quantity, which we will arbitrarily call "energy", is a fundamental property of the universe if it is true that F = ma, and that for every force there is an equal and opposite reaction force. So kinetic energy is a quantity that is constant because of Newton's laws. Newton's laws ultimately mean objects with high mass resist motion changes more.
    – Kenshin
    Commented Sep 8, 2013 at 13:48
  • 1
    You might be interested in: Oliver Pooley's "Points, particles, and structural realism" and John Earman's "Laws, Symmetry, and Symmetry Breaking; Invariance, Conservation Principles, and Objectivity.". They both discuss the first-order and second-order logical structure of scientific theories. Commented Jan 2, 2014 at 16:31
  • Albert Einstein calls Galileo the father of modern science. Galileo established what I call The Physics Paradigm. He described measurement methods and mathematical models to specify physical quantities. This paradigm is the philosophical foundation of empirical physics. Galileo described quantities of weight, position, displacement (change of position), time, velocity, and acceleration. Newton described mass and momentum (mass times velocity). Force F = ma (dp/dt = m dv/dt) is the tendency to change momentum p of mass m. Kinetic energy in a frame is K = 0.5mv^2. Work equals change in energy. Commented Jun 11, 2023 at 20:28

16 Answers 16


First of all, I would caution you against using definitions from Wikipedia when considering serious issues. I'm not a physicist, but I'm sure that the appropriate people could give you pointers to places where serious physicists have weighed in on the proper definition of "energy" and "force." (I seem to vaguely recall Feynman dealing with this in his lectures, but my memory is hazy, so don't trust me on that.)

But, since you are asking in a Philosophy forum and not a Physics forum, we can safely focus on the properly philosophical aspects of your question.

To cut to the chase, Hume is canonical reference here, and you are quite correct that we only perceive effects, and not causes, and that there is no rigorous way for us to identify what we mean by a cause except circularly through reference to the effects.

Fortunately, this doesn't make much of a difference, since there is no need to believe in a cause at all, properly speaking. You make a comparison to the statement "God is the cause due to which the universe exists"-- and that's a good analogy, because what we have here is simply a definition, not a proposition-- it adds no new knowledge. It's like saying "A shape with 3 sides, we call a triangle." The interesting (and challenging) thing comes when we wish to attribute more predicates to that definition.

In the case of "energy", we have very clear formulas that predict the effects of this occult cause, and the formulas work regardless of whether you believe in the cause or not. It doesn't matter if "energy" as a force actually exists, as long as it is adequate to the phenomena.

For me, the most useful way of framing this issue is via Fictionalism. We can treat "energy" as a fictional entity, and continue to use "energy" as a provisionally useful concept, without making any ontological claims about "energy" whatsoever.

So, to summarize: the ontological existence of "energy" may be as poorly founded as the ontological existence of "god"; however, the explanation of the effects of energy are clearly adequate to the phenomena, and can be epistemologically justified with a great deal more certainty than can be brought to bear on most religious issues.

If you can come up with a more parsimonious explanation for physical effects which does not require recourse to the concept of "energy", physicists will rejoice-- as long as the formulas still operate correctly. I leave the religious analogy as an exercise to the reader.


That isn't a cyclic argument because it's not an argument.

It's something of a cyclic definition as given there. One can do somewhat better, but you have exactly the same problem with language as a whole: it's necessarily cyclic, since you can't get started defining language without using it. So this isn't a particularly worrying state of affairs as long as you know how to use energy, force, etc. in calculations and intuitive understanding.

The argument for the definitions being useful is the gigantic amount of evidence that formulae based upon these definitions give exquisitely accurate predictions. Presumably you've noticed this in studying physics.

The logical structure of the endeavor is radically different than the logical structure of most religious practice and doctrine.

  • I agree that this isn't an argument, it's more of a definition as you have pointed out. A bad choice of words. But according to Wikipedia (Sorry about using Wiki again everyone, but this was the first resource I found online - if anyone can find a more reliable resource, please comment): 'Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe' How can we test fictional concepts like force & energy? Please elaborate.
    – Green Noob
    Commented Aug 30, 2011 at 4:12
  • @Green Noob - Y'know Newton's third law? That says one way in which force should behave. That's what you test. I'm failing to see how this is not straightforward.
    – Rex Kerr
    Commented Aug 30, 2011 at 18:34
  • I think you didn't understand my question. What I meant to say was that the fundamental concepts are inferred from the effects, not by direct observation of the cause itself. Taking Newton's 3rd law for example, consider a rocket which is launched into space. The law implies that the rocket exerts force on the ground, the ground in turn exerts a force in the opposite direction thus sending the rocket skyward. But can you prove the existence of force independently without considering its effects?
    – Green Noob
    Commented Aug 31, 2011 at 6:42
  • The way I understand it,Newton saw an object move & assumed that there must be some entity that causes this movement.This entity he called 'force'.The Newton's laws & other laws arose from this assumption,which may or may not exist.No one has ascertained the existence of force or energy for that matter by direct observation.In this respect these concepts is only as valid as the concept of God. I'm not saying that Newton's assumption is nonsense. We are yet to discover any effect which has no cause & a lot of science rests on this assumption.All I'm saying is that these are axioms,not facts
    – Green Noob
    Commented Aug 31, 2011 at 6:56
  • @Green Noob - What is wrong with saying that "force" is the sum of all of its effects?
    – Rex Kerr
    Commented Aug 31, 2011 at 14:43

In classical geometry one has to accept point and line to have a starting step, at some point we all have to accept that there is something we can agree on to have something to work with. In maths if you do logic and analysis you would end up proving 1+1=2 (eventually), but that is long after you accepted that in primary school to even be able to start stduying maths. No it is not a circular thing, but something that you accept at a naive level and then work your way up to a solid level where you are able to question it, an look for basis for it. Questioning the fundamentals is advanced stuff, that where you start to really leran.


One thing to consider, when analyzing in terms of logic, is whether the concepts you are speaking are actually relata, that is, terms in a relation.

You could make the same argument about giving. What is a gift? An object that a giver transfers ownership to a recipient. What is a giver? Someone who transfers ownership of a gift to a recipient. Then what is a recipient? Etc.

This might also look like a circular definition, but it just seems so because you are asking about particular relata without trying to define the overarching relation. The relation of giving is when someone, a giver, transfers ownership of an object, a gift, to another person, the recipient.

Similarly, instead of trying to understand what energy, work, force, etc., are on their own, you should instead try to see the overarching relationship. When I push a book to the back of my desk, the physical properties of this event are all there, but they mean nothing separately. Force, mass, and acceleration, for instance, are all related to each other, and can't really be understood independently. You might think, for instance, that force and mass can be measured separately, but when you place an object on a scale you are inferring what the mass is from the force that you are actually measuring; and similarly, you calibrate the scale by comparing the results with the masses of other objects. So you'll never be able to capture any of these relata alone divorced entirely from other physical properties.

I would suggest that the overarching relation is the physical system as a whole, which is right there in the first Wikipedia definition you cited.


Feynman is making a particular point about the abstract nature and the ontological commitments we may or may not make in physics.

It is true that since the formulas work without caring about your ontological commitments one can dispense with foundational questions about energy in a rigourous manner.

However, physicists do not think quite like that. There is a story, probably apocryphal, when Pauli, a famous physicist saw von Neumann, a famous mathematician writing out yet another theorem on the blackboard. He said, 'Johnnie, if physics were theorems, you'd make a great physicist'.

The point of this story is that physicist uses what is called physical intuition, and this is learnt by learning how successful theories have been understood, motivated and modified over centuries, the kind of questions they purport to answer, and their own sense of the behaviour of reality.

Some examples:

  1. Although Hilbert pretty much discovered Einsteins theory of General Relativity after hints from Einstein at about the same time that Einstein did; it was Einstein that got the credit because he gave the physical reasoning and not simply mathematical: he had suddenly understood the importance of why a man in free fall doesn't feel his own weight - his 'happy thought'. This actually was an old puzzle, why were there two definitions of mass - inertial & gravitational, surely nature would be economical and have only one. Einstein proposed that they were in fact the one and same definition looked at from two different perspectives - his famous equivalence principle.

  2. Heisenberg discovered his famous uncertainty principle by realising that a small enough system is always affected by the observations that we make on it. In older theories this was never a concern.

  3. Hawking discovered Hawking Radiation after he realised he couldn't disprove Bekensteins claim that thermodynamics applied to black holes, and he discovered this by noting that their horizons can only increase which reminded him of the property of entropy which only increases too.

  4. Lord Klein developed an alternative model of the atom as a knot. He couldn't get this to work and dropped it. Of course, the importance of this insight is that we are no longer considering an atom as a point particle but as a string. Much later, string theory exploded into the mainstream.

But to finally answer your question, yes, fundamental concepts do have a logical basis, but not the formal logicism of a foundationalist programme in mathematics that works from axioms, but a much more intricate relation of justifications, rationales and speculations - this is the form of its logic.


To address your specific point about what is force; it might be useful to direct your attention to Aristotles Metaphysics, specifically where he theorises on change: he notes that there needs to be something that has the capacity to cause change, and something that has the capacity to be changed; this is in general, qualitative and ontological terms Newton's second law: force causes acceleration.

It's worth contemplating the very general terms that Aristotle put this in, and also it's 'logic'; to see that it is indeed logic, one could alter the second term and suppose something that cannot be changed; then we have a famous paradox: what happens when an irresistible force meets an immoveable object.

The next step in theoretical physics is the move to Lagrangian Mechanics; which might be seen as a step away from Newtons Second Law; and the beginning of its serious mathematisation; but actually it can be put in the same form.

It shows how Newton, and behind him Aristotle is still basic to Physics; but it's hidden behind a now quite forbidding edifice.


Your question was first addressed by Newton himself in his famous remark, "hypotheses non fingo" or "I frame no hypothesis" in regard to the existence, meaning, or ontology of "gravity."

The Cartesians were alarmed that this invisible force "gravity" introduced yet another non-empirical and metaphysical agency into the "natural" philosophy. How could it be a "cause" if we cannot even see it? How can it act mechanically "at a distance" with nothing between objects to cause their motion? The same applied to the "infinitesimals" used in Newton's calculus. Were they something or not?

The subsequent empiricism from Locke to Hume steadily eroded any foundational belief in these unseen "causes." Hume famously demolished the very idea of "cause," while Berkeley gave his famous demonstration that this notion of "matter" upon which "materialism" is based is no more demonstrable than God.

So, such questions as have occurred to you have indeed accompanied modern physics since its birth and, in truth, have never really been settled. The "positivist" compromise simply defined scientific concepts functionally as what works. If the math is consistent, the predictions correct, and the experiments repeatable the "useful fiction" stands until it is falsified, reduced, or replaced. Worst of all, even Occam's Razor, so essential for theory selection (to wit, the greater "parsimony" in M. Dorfman's fine answer) cannot in any way be "proven" or founded "in reality."

Paradoxically, the very success of modern physics depends fundamentally on ignoring such questions. Physics says "how" but never ultimately "why" or "what." The classic example is quantum theory, which works perfectly in engineering and is mathematically precise, yet know one knows what on earth we are talking about. We cannot even imagine the "reality" in any experiential terms. To ontology, physics says, in effect: Don't ask, don't tell.

Though the working physicist leaves ontology at the doorstep, many physicists, usually the greatest ones, have thought and written much about these matters. You might take a look at Heisenberg's "Physics and Philosophy" or Paul Davies "The Matter Myth" or works by Bohr. When "off duty" these minds cannot help it. They are nagged by your very questions and need to get at the "reality" behind them.


"Energy is often understood as the ability a physical system has to do work on other physical systems."

"In physics, work is the amount of energy transferred by a force acting through a distance in the direction of the force."

"In physics, a force is any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape."

In other words: A body has energy which it can use to do work on another body, this body may transfer energy into another body to do work, and the other body is experiencing a force as a result of the previous body's work.

This doesn't seem to be a problem logically speaking.

What is force? Force is the result of work. That is it's the event of energy being put into a body to change it's state.

I will however concede to the point that some of Scientific claims are very much as baseless as any religious claim, or that religious hypotheses are rejected for some reason that could easily reject other scientific claims, But I do not think your examples are good ones.

If you intend to prove that some religious claims are just as good as a scientific claim, I would suggest that you look up falsifiability, which the institution of science seems to think is an excellent way to demarcate scientific thought from all else, and has become a criterion for any new hypothesis. Consider the concept of the indivisible unit that science has been concerned with since the dawn of time, String theory, and other sciences that don't have a method by which an observation can be made to find them false. These are somehow immune to this exception for no good reason...


I just landed on this forum and I'm quite disappointed that I couldn't find an acceptable answer to this question. Especially this Feynman lectures thing. I think this is a cult of personality and that his statements and weird analogies bring more questions than answers.

I think that the philosophical questions behind science is not what is a force or what is energy. Those things are definitions. They are not assumptions. They are definitions based on assumptions. To question science you must question the assumptions not the definitions.

I've found an answer to the question what is a force. It is an answer which is quite good I think so I'll share it here.

What is a force?

It is pretty simple. A force is a derived unit. A derived unit was built by a definition. The definition of a force states that F = ma. So a force is a mass multiplied by an acceleration. From a philosophical point of view, a force doesn't exist by itself in nature. You observe that there is a force by concepts of mass and acceleration.

Actually, an acceleration can be broken down to meters and seconds. So you have kgs, meters and seconds. So you observe that there is a force by concepts of kg, meter and second.

You cannot say an object moves because a force is applied on it. What you can say is that this object crosses some distance, in some time and this object has a certain mass. It thus have forces applied to it. Both these statements have very different meanings. One means that the force exists by itself in nature. One means that the force is a definition.

Basic SI units have definitions as well. The definitions for base SI units are more philosophical and have root in our senses.

What is the meter?

Our senses allow us to create the concept of distance. So distance is the debatable concept. Scientists have seen distance as an important concept for a long time. They thus created the meter. Today the meter is accepted as is because we use it everyday. But at first the meter had to be created. The meter didn't exist before its definition. So we had to take a short distance, build a bar of metal of that same length and say this will be the meter. At first, this was sufficient. After, we had to create a more precise definition based on light. So now you have the concept of the meter built from scratch from a simple concept: the distance.

What is time?

For time, it's the same. I like to see time as the course of events. The second (s) is defined to be a certain event which happens always in the same lapse of time. (the fixed numerical value of the caesium frequency ∆νCs, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1). I don't understand the formal definition very well, but I understand the concept of time and second. Again, you cannot say an event happened because a second has passed. You can say a second has passed because a certain event happened. Those two statements are completely different.

For the kg, it is again similar. So you have the force being defined by these 3 different definitions (kg, meter and second). These 3 definitions are basic concepts which can be considered assumptions. Even though they are very strong assumptions, they can be discussed. The force cannot.

What is energy?

For energy, it is similar to the force. It is a derived unit. You cannot say an object is heating because it has energy. You can say an object is heating so it has energy. Again the Joule (unit of energy) is defined in terms of mass, time and distance. Energy doesn't exist by itself in nature. It is a definition. It exists by concepts of mass, time and distance. Because an object with a certain mass is crossing distances in a certain time, it has some energy.

  • Agreed about Feynman. If he said "I dunno" or "we dunno" he would have saved everyone a lot of time. Or he could have said "we dunno, but the math works"... which he did, but using up an unneeded 1000 words doing so. Commented May 9 at 5:03

You are trying to learn about energy in a way that many philosophers endorse, but is deeply anti-rational. That is, you're looking at the definitions of terms and trying to work out what's going on from definitions.

The idea is that if you have a correct definition and work out its implications, then what you have worked out is bound to be correct. This is wrong for several reasons.

This takes for granted the false idea that it is possible to show an idea is true or probably true by argument. Any argument uses premises and rules of inference, whose truth or validity can't be guaranteed. If you just assert they are true, then you're guessing and should acknowledge that fact. If you say they are to be proved by some other argument, then you have the same problem with respect to your new argument. In reality, you guess about how things work. Facts and arguments help you to find problems with your guesses, e.g. - incompatibilities with other ideas, or with experimental results etc. See Chapter I of "Realism and the Aim of Science" by Karl Popper, for more details.

In this specific case, you're treating the definitions as if they are supposed to prove something, when they are totally incapable of filling that role. Definitions always use undefined terms, so they can never be used to construct a theory on a firm foundation or anything like that. As a result there is a limit to the precision of definitions, and this is a feature not a bug.

The way to think about definitions is to treat them as abbreviations of ideas. To understand what's going on you understand the ideas. The definitions help you shorten statements of those ideas so you can make discoveries about more complicated stuff. You only have to make the definition more precise if it will help you to explain something better. Adding additional precision makes the ideas involved less clear by introducing lots of unnecessary complication. In addition, trying to learn theories by concentrating on definitions involves breaking the idea up into lots of parts that overlap to some extent and so involves duplication of effort, and may introduce additional confusion. If you understand Newtonian mechanics or whatever and then summarise that understanding using terms you will understand the relations between the relevant terms more easily.

For more on definitions, see chapter 11 of "The Open Society and Its Enemies" by Popper and "On the Sources of Knowledge and of Ignorance": the introduction to "Conjectures and Refutations" by Popper.

  • The famous mathematicion David Hilbert, in his list of problems given at a conference in 1900, gave number 6 as, to oversimplify, axiomatize physics. So it was seen as something as possible to do and desired to do so.
  • one -can- define things circularly, and in some sense, that makes them equivalent, or at least only relatively supportable. So one could say that energy and work define each other, and however inchoate your conception of either of those concepts may be individually, together they are very well defined.
  • these concepts, like energy/work/force/pressure/volume/velocity/time/etc, come from centuries of teasing out (by experiment and thought) exactly what they mean. There is no guarantee of -the- final answer but certainly refinement. The one line summary of the concept really can't be expected to do the entire concept justice.
  • it is common to notice similarities between science and religion; they both rely on faith/authority, they both attempt to explain the world, etc. But the kind of faith /explanation/whatever is very different. Science -depends- on repeatable data and theoretical (one could make a case that religion does too but it is not necessary for religion). If an authority is invoked in science, it is expected that the statements of the authority can be checked by repeating an experiment or thought process (there is not faith in faith).
  • 1
    And really..wikipedia and wiktionary, as much as it is great that they exist with all the democracy and stuff, one should have more doubts about it than a more authoritative resource like say a physics text book.
    – Mitch
    Commented Aug 29, 2011 at 14:27
  • The concept of GOD, does not rely on faith or authority: it was observed.
    – Marxos
    Commented Jun 27, 2022 at 16:12
  • @Marxos I think all three of those are accepted (in different ways, by different religious groups) as bases for such a concept.
    – Mitch
    Commented Jun 27, 2022 at 18:41

I am neither a mathematician nor a physicist but was a teacher of math, a painter nowadays. One day I started reading math and physics again by putting simple questions and asking how do they approach these questions nowadays and in former times(Aristotle). The first law of Newton was already known in ancient times in China. The concepts time, change, mass, force and energy were one of these questions and tried to figure out how to handle that and still trying to figure out what it is. I used the idea of transport of mass for force and transport of force for energy and also that moving objects can be used to move other objects. How to incorporate it is another question and depends highly on math. Anyhow, I enjoyed reading the answers but if Feynman is correct with his introduction of energy? I doubt it. Nevertheless, I like studying Feynma's lectures. I still do have a lot of questions which are basicly philosophical to my opinion. Par example: time is introduced by pointing to an orbital movement of the earth around the sun but represent time as a linear structure just like length in order to do math calculations.

  • 1
    While this is some of a reflection about energy, it hardly is an answer to the question and lacking of any reference for its claims.
    – Philip Klöcking
    Commented Nov 8, 2015 at 9:54

The philosophical foundations for physics, presently, that I can imagine at the moment, is that reality is consistent and that observers aren't being tricked.

Pretty shaky, indeed, however, there is a purely mathematical and geometrical model of the universe that premises everything on a minimal set of functions which would have to exist, in order for the universe to be as it is.

For example, a mathematical graph can relate everything to everything else, even in the 4-dimensional spacetime. If one adds to that an additional layer of relationships, such that nodes in the graph can be a graph in itself, then you can also account for atoms and cosmos-scale relationships.

So, one can start to imagine a more well-founded physics.


I agree with the observation that the Wikipedia definitions (but really article introductions which is not quite a definition) are insufficient. I've wrestled with these issues a good bit myself, and in trying to educate other people in physics.

I believe there is a notable missing piece here, which is geometry. I find that people will very often question the philosophical basis of physics, but when I challenge them to question the philosophical basis of geometry, they don't even understand what I'm talking about. In reality though, geometry was the fist in the progression of a scientific worldview. Geometry is a perquisite for physics in the truest sense. Now, let me echo something from a previous answer.

To cut to the chase, Hume is canonical reference here, and you are quite correct that we only perceive effects, and not causes, and that there is no rigorous way for us to identify what we mean by a cause except circularly through reference to the effects.

I want to drive a little in the direction of perception, and the basis for believing that we have observed something. It is apparent to most people that we live in a 3-dimensional world, as evidenced by their senses, but the idea of 3 dimensions is a geometric concept. Geometry applies rules that demand consistency of statements regarding a real observed phenomena. That real phenomena is the apparently 3-D (+time), apparently Euclidean space that we live in.

Basic Newtonian kinematics extends the tenants of geometry to motion of objects. I think that a major roadblock here is the question of "what is our perception?" If one fully accepts the tenants of geometry, then they can simply make a definition of perception that is the evolution of the geometric form of the world around them over time. If you do that, Newtonian kinematics is not lacking anything in terms of physical justification because it is demonstrated to be very well reproducible. Values such as mass and energy are not derivable from the basics of geometry although a value such as volume is. These values that arise in the formulation of physics that were not present previously can be taken as nothing more than an intermediary - something introduced in order to maintain a consistent set of laws.

For this question, I think that what I've written is sufficient for the philosophical justification of physics with the assumptions I've mentioned (like acceptance of geometry), but I want to take a step back before concluding. Our perception is not exactly that of 3-D Euclidean space + time. From the moment we gain consciousness we find ourselves experiencing that geometry, but we only experience it indirectly, through other senses that are both:

  • Lower dimensional
  • Imperfect

Our vision may be 2D, but just like a computer screen, the smallest detail that can be represented is limited. These days, we have a very good intuition due to computers that a higher dimensional concept can be mimicked by a lower dimensional source of information, provided that it is not represented in infinite detail. I think this allows us to break off from the false notion of perception of the "obvious" world around us, and reduces the problem to that fact, the simple observation, that we have senses. Beyond that, consistent laws can be formulated for what we see through those senses. Physics, and more specifically the mechanics you re is merely one stage in that process.


Physics is derived from givens. It is given there is matter. Newton describes it.Careful observation shows that there are clouds . Geometry is a good basis. Accepting points and lines are accepting flaws. Rearanging things we are left with clouds and a discription and no basis. Working with this we need a basis. Start defining a point as a physical object of varying dimention and a line as a physical extention. The point will have to become part of the line. The point will have to spread out and become the line. So our basis will be a point that disapeared and became a spread out entity. Point b of the line can't exist so the line could be going anywhere. This is our basis. This is a good basis for logic in physics because everything exists for sure not just a given. Now there is a discription. Looking up images of atoms using the electron scanning microscopes you will see a cone of cloud that makes up an atom. Physical basis. Since there are more than one of them there is a point b. So you have a quantum entangle. Hydrogen is the simplest form of so called matter and combines in numbers to form other elements. The connections between the elements used as matter match the discription of matter. Physical basis. Discription. Cloud. Quantum ring interactions. The mathmatical basis is simple geometry. There now appears to be a simple logic relation to physics. Deducing to only solid basis a circle cannot exist in geometry nor can a single triangle. A cone can exist. So a circle might really be half a triangle or something explaining the weird number.

  • You don't seem to really engage with the question. How can the concepts of energy, force or mass be put on the basis of geometry?
    – viuser
    Commented Feb 26, 2017 at 7:15

I offer the following as a work of philosophical intuition in that I have never studied the formal rules of logic nor have I rigorously studied physics or philosophy. It is not an explanation of what energy IS, but rather a suggestion of what it might represent. Please feel free to run this through a shredder if it doesn't stand up to scrutiny I'm happy to accept that.

I begin first with my conclusion: energy is the FUNDAMENTAL "stuff" or "essence" of existence itself.

An analogy is that energy is to existence as air is to an atmosphere and water is to an ocean. The difference is that energy is an irreducible property or "thing" while air and water are reducible to smaller and smaller entities until we conclude that they are both complex manifestations of "energy". (matter <=> energy)

"Existence", of course, is an elusive concept that can consume an entire library of works spanning metaphysics, philosophy of language, and philosophical logic. Glossing over all of that, since I am ignorant of most of it, I make the assumption that existence MUST exist and that non-existence is a sublime fiction. To clarify, existence cannot not-exist. There is existence that contains physical matter and existence that is devoid of physical matter - two states of one thing. Two sides of the same metaphysical coin.

If existence has no state of non-being, it has no beginning or end. It is infinite and universal. In my view, existence can be thought of mathematically as {the set of all things that are possible}. No thing or event that is possible can exist exclusive of this set. No thing can exist outside of existence. A corollary property of {the set of all possible things} is that it must include the information or knowledge of all things. No information can be exclusive of it. I offer this as an interesting excursion you might take, but it has no direct bearing on my premise.

Now let's leap back to energy and consider the law of conservation of energy. In a closed system, the balance of energy remains constant. Is not existence a "closed system" as I have presented it? Nothing can enter or leave existence because it is all-inclusive. Energy cannot enter or leave existence. It must always exist just as existence must always exist. Hence the "law" of conservation of energy must be true and must always be true.

If existence itself can have no beginning or end, then energy too must have no beginning or end. They are both infinite. Because no thing, or property of a thing, or information about a thing can exist outside of existence, then energy can be considered a necessary property of existence. Because all matter (including objects and radiation) is a manifestation of energy, can energy be considered equivalent to existence? What other property could existence possibly have? Time? No, that is a property of matter. Dimension? No, that is also an property of matter. they are secondary properties, or artifacts of existence, not fundamental properties.

Now I'll make a leap into another frying pan. If existence must exist, and is therefore infinite, it can be said to be omipresent ("oh no, here he goes!"). If existence represents the {set of all things that are possible}, it can be said to be omnipotent because in an infinite system, all things that can occur will eventually occur. If existence must contain the information about all things possible, then IF existence had conscience (awareness) then it could be said to be omniscient. Since existence contains all possible things, it must necessarily contain awareness. Omnipotence, omnipresence and omniscience are properties associated with "god". Therefore, god (or God) is not something that is separate from existence and can create existence, god is existence itself, and it's fundamental property is energy.

As I said in the beginning, please dissect and shred this theory. It is probably circular logic and it probably violates all sorts of other logical and philosophical principles, but there it stands as my own uneducated "best guess".

  • 1
    Hi and welcome to philosophy.se! Please don't be mad or discouraged if I say this, but your answer does not follow the rules we have here. We're not doing philosophy here, but mostly scavenging what has been said by famous people. You might find that boring, but that's how it is. While your personal opinion might be very insightful, you're supposed to be quoting and referencing the authorities, whoever that might be in the specific case. Your "uneducated best guess" won't do. Maybe you want to have another look at the FAQs, and don't be scared to ask on META.
    – iphigenie
    Commented Dec 29, 2013 at 20:13
  • Ah, sorry. No, I hadn't done that. Just saw the post in surfing about and then launched right in. However, some of my ideas are drawn from recognized sources even if I haven't cited them. I'll have a look at the FAQ's. Commented Dec 29, 2013 at 22:57

While reading the question, the inner voice in my head kept shouting Feynman, Feynman. By coincidence, earlier this week I was reading his discussion concerning the nature of forces and in particular cyclic definitions and the relation between math and physics:


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