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What is energy, exactly?


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That’s the skepticism that has reached us through the Enlightenment. Those that refuse skepticism in the realm of science then, and denigrate it, and recklessly rely on an “Unquestionable Authority“, they are ultimately placing themselves outside of Science itself, and outside of nearly four hundred years of philosophy if not more.

I am skeptical of both god and “absolute nothing" ....that doesn't mean that I don't believe god or "absolute nothing" could exist...

Actually it is exactly the opposite..I believe that god and "absolute nothing" could exist... TRUE science(being open to ANY skepticism or falsification) though is the only thing that could possibly prove it… and it has nothing to do with belief.

 

I am a TRUE scientist and a TRUE agnostic and a FALSE believer if know what I am getting at.

I believe things but I know that they could be false until they are TRULY scientifically proven....

So what is energy, EXACTLY????

 

 

The Bohr–Einstein debates were a series of public disputes about quantum mechanics between Albert Einstein and Niels Bohr, who were two of its founders. Their debates are remembered because of their importance to the philosophy of science.

 

Einstein was the first physicist to say that Planck's discovery of the quantum (h) would require a rewriting of physics. As though to prove his point, in 1905 he proposed that light sometimes acts as a particle which he called a light quantum (now called the photon). Bohr was one of the most vocal opponents of the photon idea and did not openly embrace it until 1925

 

Even when studying quantum mechanics and regular physics you have to open to the fact that there could be a flaw in the logic of these extraordinary human beings. Who was right? Einstein or Bohr? Maybe they were both right but maybe you can find something they explained is wrong due to a new discovery in the universe. I am not saying they were wrong on anything they investigated and explained … I am just saying always be open to the possibility AND then you will be a TRUE scientist.

 

You can put the HUMAN beings(Einstein, Bohr) on a pedestal of respect.. but you cannot put SCIENCE on a pedestal …..we must always be skeptical of science(even if it is TRUE) in order for it to be TRUE science. There is only one TRUE science(I mean TRUE “god”, I mean TRUE “absolute nothing”) and I sure as hell don’t think we have found it yet.

 

The next shock came in 1926 when Max Born proposed that the mechanics was to be understood as a probability without any causal explanation.

 

Einstein rejected this interpretation. In a 1926 letter to Max Born, Einstein wrote: "I, at any rate, am convinced that He [God] does not throw dice." < That quote I do not believe is TRUE science…but if it is, it is....TRUE that is...but I will still be skeptical.

 

 

 

Sooo....what is energy, EXACTLY?

 

"I, at any rate, am convinced that He [God] does not throw dice."...I do sympathize with Einstein though he probably put in tons and tons of thought to come up with that conclusion.

 

Another quote...

 

"A century later, all of nature had been classified into two great domains:

 

1)There was energy, the forces that animated objects

2) and there was mass, the physical stuff that made up those objects."

 

If the big bang is real..how did the forces(energy) initially animate mass if they weren't physically real?

AKA what is energy, EXACTLY?

 

So I guess to be more specific so somebody doesn't just give me a wiki link(http://en.wikipedia.org/wiki/Energy), I will ask a more specific question...but it is not the only question..

 

Is energy(joules, kilo-watt hours...or whatever) a physical thing on the subatomic quantum scale?

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No, it's not a physical thing. It's a useful abstraction because it is a conserved quantity owing to the time-translation symmetry of physics. It helps us keep a good set of books for problems we so

I think everyone would benefit from reading this: http://www.colorado.edu/physics/phys1110/phys1110_fa10/Feynman_energy.pdf .

Err there is a lowest energy. It is called the Zero Point Energy and always corresponds to   [math]\frac{1}{2} \hbar \omega[/math]   Of any quantum of energy.   This is why we say, ''the lowest

Is energy(joules, kilo-watt hours...or whatever) a physical thing on the subatomic quantum scale?

 

No, it's not a physical thing. It's a useful abstraction because it is a conserved quantity owing to the time-translation symmetry of physics. It helps us keep a good set of books for problems we solve.

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I would have to disagree swansont, if you are referring to energy not being a physical thing. But if you are referring to joules, kilo-watt hrs, etc... then I would have to agree. This has always interested me from a distance. E=mc2, to think that mass traveling that fast would be pure energy. I've always wanted to ask those who believe in time travel if they thought the mass that energy is, is traveling backwards in time.

 

I've also wondered what energy is. Is it anything that gives off heat or exzerts force? Is it just molecular reaction and we just generallize it by calling it the same name no matter from what source it comes from? And what about the sources of energy that we don't fully understand, such as gravity or field energies period. To be defined as energy it would still have to hold mass at twice the speed of light, wouldn't it? Being a distant observer there are probably answers to these questions and I've just not gotten around to finding them.

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Energy is the thing which enables you to have some effect on something else. The sun heats the earth. Your car burns gas to get you to work. You push a car up a hill. The sun heats solar panels which store electricity. Your body burns ATP. Gatorade gives you a quick sugar rush. Nitrous oxide creates extra energy to help you beat the other car.

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The thermodynamic definition of energy is the capacity to do work. So you can think of it as the "thing" that is responsible for movement or change, but that is imprecise.

 

The best modern definition is as swansont and DrRocket state: "energy is the conserved charge related to time-translation invariance of a Lagrangian".

 

Basically, if the physics does not depend on time then energy is conserved. I do not think you will find a better answer than this.

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I would have to disagree swansont, if you are referring to energy not being a physical thing. But if you are referring to joules, kilo-watt hrs, etc... then I would have to agree. This has always interested me from a distance. E=mc2, to think that mass traveling that fast would be pure energy. I've always wanted to ask those who believe in time travel if they thought the mass that energy is, is traveling backwards in time.

 

I've also wondered what energy is. Is it anything that gives off heat or exzerts force? Is it just molecular reaction and we just generallize it by calling it the same name no matter from what source it comes from? And what about the sources of energy that we don't fully understand, such as gravity or field energies period. To be defined as energy it would still have to hold mass at twice the speed of light, wouldn't it? Being a distant observer there are probably answers to these questions and I've just not gotten around to finding them.

 

First of all, I'd like to point out that there is no such thing as an "energy particle". There are messenger particles of different forces which can transmit energy (eg. the photon), but inside them we don't find "energons". Energy is an abstract concept; the ability to do work. These particles merely possess that ability.

 

You also seem to have a very strange understanding of Einstein's E=mc2 formula. It simply shows that matter and energy are equivalent that energy has mass and that matter has energy, and that you can change matter into energy and vice versa. If you're interested have a read of the wikipedia article here.

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in my opinion there are 4 entities in the universe, including energy (you can see the others in my thread post) Regardless, hope this helps

~Gabe

 

In the opinion of Aristotle there were also 4 basic entities -- Earth, Air, Fire and Water.

 

You are just as wrong as he was. But Aristotle had the excuse of the non-existence of modern science. What is your excuse ?

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The thermodynamic definition of energy is the capacity to do work. So you can think of it as the "thing" that is responsible for movement or change

 

perhaps, considering photons, E = pc = mc2, i.e. "there is only one fundamental substance, energy-momentum-mass" ? Via such explanation, energy can do work, i.e. exert forces, i.e. alter momentum, [math]W = F d = \frac{\Delta p}{\Delta t} d[/math]. Intuitively, I like the definition, that "energy is that which is capable of exerting forces, i.e. force-fully influencing its environment", i.e. energy represents a "battery-storage" of force.

Edited by Widdekind
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perhaps, considering photons, E = pc = mc2, [

 

What is m?

 

In general for physical particle we have

 

[math]E^{2}-p^{2}c^{2} = m^{2}c^{4}[/math],

 

and for massless particles, such as photons this becomes

 

[math]E = pc[/math].

 

This shows that photons carry momentum and that this is really just the energy, up to the factor of c.

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"there is only one fundamental substance, energy-momentum-mass"

 

None of those are substances, though. Each is a property, an abstraction, and each is useful in solving various problems.

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in my opinion there are 4 entities in the universe, including energy (you can see the others in my thread post) Regardless, hope this helps

~Gabe

!

Moderator Note

thislilpiggy, promoting your own threads in someone else's is considered hijacking, and is against the rules you agreed to when you joined. Please refrain from doing this in the future; there is no need to respond to this modnote.

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The concept of 'energy' is not confined to Physics only. What about informational energy (Shannon's concepts). Also biological energy (in the form of ATP etc), and metaphysical notions of energy. But, I suspect, if one goes deep enough, there will be common grounds for any type of energy, a 'thing' that makes stuff happen

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Shannon's concepts are purely abstract and even Schroedinger's wave function is purely abstract. Biophysics and Biochemistry accounts for biological energy, its no special thing.

 

(I am very confused and skeptical as to what this abstract concepts represent in the external physical world, its a philosophical problem)

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The concept of 'energy' is not confined to Physics only. What about informational energy (Shannon's concepts). Also biological energy (in the form of ATP etc), and metaphysical notions of energy. But, I suspect, if one goes deep enough, there will be common grounds for any type of energy, a 'thing' that makes stuff happen

 

Shannon had no concept of "informational energy". He did develop the important concept of entropy in the context of information theory and that concept mirrors the definition of entropy from statistical mechanics.

 

This is physics forum and only the definitions of energy that are pertinent to physics are germane to this discussion. Metaphysics is completely irrelevant, and largely useless. See elfmotat's link to a discussion of energy by Richard Feynman. It is quite clear.

 

My 8th grade education and my 14 year old age Dr. Rocket, and When i say entities, i mean the different things that make this universe flow. Why so angry?

 

No anger.

 

But I would have hoped for much greater understanding of science and sentence construction by the time that someone reaches your age and level of schooling.

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Swansont is very correct. Energy is defined as 'the ability to do work'. Therefore, energy is a qualification or an adjective. However, it is currently used in every aspect, where an undefined term is required to represent cause of an action.

Edited by matterdoc
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Swansont is very correct. Energy is defined as 'the ability to do work'. Therefore, energy is a qualification or an adjective. However, it is currently used in every aspect, where an undefined term is required to represent cause of an action.

 

Better read elfmotat's link.

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From the basic fundamental dynamic level of reality represented by a unit quantum wave, to a catastrophic collision between planets, there is a specific magnitude of that phenomenon humans recognise as force intrinsically associated with all motion. The all-embracing name given to that motion-force is energy.

 

 

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I can understand that based off of our concrete knowledge of energy that all we can say for certain is that it is a quantity that is always conserved, but it's hard to think it isn't physical in anyway, especially considering its equivalent to mass, and if we find a higg's boson, it's pretty much physical energy because higg's bosons would be actual particle's that are responsible for mass that are therefore equal to energy.

And what about a photon too? What is a photon besides energy? What exactly is "waving" when you say it's an EM wave?

Edited by questionposter
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I find the explanation in terms of a lagrangian deeply circular and unsatisfactory. The lagrangian is defined in terms of energy!

 

The honest truth is that we don't know what energy is, although we do know a great deal about it and how to process it mathematically.

 

In all systems of rational thought we have to start somewhere.

We start with some concepts that are taken for granted or given and the system of rational thought is then about the development of relationships between these concepts.

 

We identify at least three types of concept:

 

Definitions

Axioms

Rules

 

All of which are stated without proof or much explanation.

 

For example what is matter?

 

Well, matter is made of molecules,

molecules are made of atoms

atoms are made of protons, neutrons, electons

protons etc are made of quarks

 

quarks are made of....?

 

At the bottom of the heirarchy there is always something that we have to take on trust.

 

Energy is just such an entity.

 

What you are asking is a definition in terms of something 'more fundamental'. We don't have anything more fundamental at the present state of our knowledge.

 

go well

Edited by studiot
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Energy is, exactly, the conserved current related to time invariance of the Lagrangian. Google "Noether's theorem".

That is not a definition of energy, it's an equality.

 

Studiot - Regarding your response to an attempt at defining energy in terms of the Lagrangian. I highly admire your response to that attempt at a definition. I totally missed that circularity part! Way to go! Bravo my good sir! :rolleyes:

 

Energy, like several quantities in physics, is one of those things that goes without a definition. I did some research on energy and wrote up th result of what I thought best suited as a good response to the question What is Energy? As Richard Feynman wrote in The Feynman Lectures (see http://home.comcast.net/~peter.m.brown/mech/what_is_energy.htm)

 

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 tht way. However, there are formulas for calculating some numerical quantity, and we at 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.

 

The concept of 'energy' is not confined to Physics only. What about informational energy (Shannon's concepts). Also biological energy (in the form of ATP etc), and metaphysical notions of energy. But, I suspect, if one goes deep enough, there will be common grounds for any type of energy, a 'thing' that makes stuff happen

As I recall, ATP is a conserved quantity which is conserved and whose units are that of that of energy, so really it's a physics kind of "energy".

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