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"Energy"

Ya know that's the nice thing about ignorance. It's curable. Thanks. Now I know I was looking at it all wrong.
 
In fact, energy is not really a noun at all. Energy is a measurement of something's ability to perform work. Given this context, when spiritualists talk about your body's energy fields, they're really saying nothing that's even remotely meaningful. Yet this kind of talk has become so pervasive in our society that the vast majority of Americans accept that energy exists as a self-contained force, floating around in glowing clouds, and can be commanded by spiritualist adepts to do just about anything.
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While people undoubtedly claim to harness real magic and refer to it as energy, "energy" is most often simply used to refer to the mundane politics of the human body (although why anyone would use magic to refer to bodily functions is anyone's guess..), and involves corruptions of associative thinking, a conversational example of which being: "Man, that pint of Ben & Jerry's in the freezer has a gravity well of 5 g's. So I had a Cherry Coke and a Pop Tart, which surprisingly blocked it's energy by 40%.". It's stupid and not necessary but makes for curious rhetoric. Just not transcendent reality or human destiny..
 
I think we are all clear on what energy is not.
I would appreciate a concise definition of what it is.

(And, as JustGeoff would say- "What does "is" mean , in the context of the question?")
 
Out of interest, how solid is the scientific definition of energy? I know it's "the ability to do work" but does that get to the nub of it?
 
Macroscopically energy is defined as the ability to do work. If you are limiting yourself to classical mechanics the defnition is solid (but arbitrary in the sense that there is no absolute energy scale). If so inclined you can also define energy through the Hamiltonian function. The former approach is Newtonian and the latter is...Hamiltonian.

In thermodynamics there are several concepts that use the word 'energy'. For instance you have one energy which is the ability to do work when the temperature is kept constant (Helmholtz free energy) and another which is the ability to do work when the pressure is kept constant etc. In any case thermodynamic energy is a well-defined quantity. One could argue that absolute zero introduces an absolute energy scale, but moving into those regions one really should take quantum mechanical effects into consideration.

Energy in quantum mechanics is defined as the eigenvalue of a certain mathematical operation. This is a mathematically more rigorous definition, that reduces to the classical concept of energy in the proper limit. There is also an absolute scale since every qmechanical system has a lowest energy state.
 
Splossy said:
Out of interest, how solid is the scientific definition of energy? I know it's "the ability to do work" but does that get to the nub of it?
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I like "The ability of a system to lift a weight located outside the system".

Quiz for the confused: Which would give you more energy if you ate it: half a cup of hydrogenated shortening, or two Vivarin and a cup of green tea with ginseng?
 
phildonnia said:
I like "The ability of a system to lift a weight located outside the system".

Quiz for the confused: Which would give you more energy if you ate it: half a cup of hydrogenated shortening, or two Vivarin and a cup of green tea with ginseng?
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The Vivarin and tea. Eating half a cup of shortening would just make me throw up.
 
Soapy Sam said:
I think we are all clear on what energy is not.
I would appreciate a concise definition of what it is.
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A fluctuation of mind and matter over time in eternity?

(And, as JustGeoff would say- "What does "is" mean , in the context of the question?")
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Circumstance, or frame of reference, with respect to time. In short, all configurations of matter and the equilibrium between matter and space that can exist, should, but apparently when this happens everything else ceases to exist. What is fascinating about this freezing sh-thole is every force seems to be in complete balance. Even more fascinating (or important) is how you end up where you do. Recognizing one's fortunate state, and also recognizing that it's possible to have sex with Kim Jong II another trillion times, one should try their best to get out of this mess, and perhaps not piss the almighty off again.

:dio:

Heaven opened it's doors to me,
at a quarter past three on the clock of eternity
What can I say it was all rich
But that still doesn't mean
that evangelist isn't
a greedy sonofab-tch.
 
Fell said:
.... In any case thermodynamic energy is a well-defined quantity...
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I see. "Quantity" of what, exactly?

Energy in quantum mechanics is defined as the eigenvalue of a certain mathematical operation.
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How very unhelpful, until you describe the essence of what is being defined.


Aww, who cares; we all have faith energy Exists (even if none of us -- or anyone else -- has the vaguest clue as to "what it IS"). Or maybe we should buy into the OP???? ROTFL :D
 
I wonder if maybe a lot of the woo ideas on energy have their basis in a bad interpretation of the old "ether" based physics? It would seem to fit their idea of some invisible pervading field that they can tap into to get whatever their little hearts desire.

Mind you, I don't discount the possibility of ether, it's just that the Theory of Relativity is able to explain the mechanics of the universe just as well, without the need for some undetectable "ether".

As always, I remain receptive to new evidence though :)
 
hammegk said:
I see. "Quantity" of what, exactly?
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I think he meant Energy is a number. It's not a quantity of any 'thing', it's just a quantity.

Like if I have 100 dollars, what is it I have 100 of? Nothing really, but the number describes precisely how many burritos I could acquire.
 
hammegk said:
How very unhelpful, until you describe the essence of what is being defined.
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As I wrote previously there are many different physical concepts that we call 'energy', all of them are purely abstracts. By that I mean that there is no way to directly measure the energy of a system. We can, however, measure e.g. position and momentum and from those calculate the energy. Energy is just a mathematical function of the relevant variables (velocity, position, area, curvature, rest mass etc.).

What is then the use of constructing such a function? The nice thing about energy that it is conserved in all physical processes (several caveats here) and is therefore an extremely useful bookkeeping tool when studying a system.
 
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