What Is Energy: Unveiling the Mystery

[Nano-Passion]

Post edited 12/29/10.

From the scientific point of view not philosophical.. Do we really understand what energy is else than a simplistic definition of its existence?

We know that there are different types of energy such as:

Heat
Kinetic
Chemical
Nuclear
Mass
Electrical Energy
Radiant
Gravitational

How does energy interact with space? I don't really understand it.

Einstein says that gravitational energy interacts with space by bending it. What about all of the other types of energies? What is really going on under our eyes? I don't believe we understand it all, in fact, it would be very foolish to say so.

For example how does electrical energy interact with space? What about heat?

From what I know, heat can make atoms jiggle more out of their molecular position for instance.

So does this mean heat excites the fabric of space in some way?

 

[russ_watters]

KE=1/2 mV^2
PE=mgh

Definition: energy is the capacity to do work.
work=force*distance

Nothing vague about any of that.

 

[Nano-Passion]

KE=1/2 mV^2
PE=mgh

Definition: energy is the capacity to do work.
work=force*distance

Nothing vague about any of that.

What I am not looking for is the definition of energy, but what it really is.

Energy changes forms (see conversation of energy), it can be gravitational or electrical.

For example, in electrical energy we say that positive and negative ions attracts. But what is the underlying mechanism going on?

I don't want to know the textbook definition of energy, but what it TRULY is.

Surely it is not a simple question, we don't understand the concept as much as we think that we do.

 

[russ_watters]

What I am not looking for is the definition of energy, but what it really is... I don't want to know the textbook definition of energy, but what it TRULY is.

That's a self-contradiction: the definition (both in words and in math) is what it is. That's the entire point of a definition!

Energy changes forms (see conversation of energy), it can be gravitational or electrical.

Yes.

For example, in electrical energy we say that positive and negative ions attracts. But what is the underlying mechanism going on?

Electromagnetic energy comes from moving charge with a certain voltage. It is very similar to mechanical work.

Surely it is not a simple question, we don't understand the concept as much as we think that we do.

No, it is a simple question, you just don't like the answer! You want it to be more complicated than it really is.

Have you read the wiki on energy yet?

 

[Nano-Passion]

No, it is a simple question, you just don't like the answer! You want it to be more complicated than it really is.

Have you read the wiki on energy yet?

True, probably because I feel we do not truly understand it! I partly believe that if we truly understand it we would be much closer to a unified theory of Quantum Gravity or generally much more knowledgeable in physics. We don't understand many things, so sometimes we will say it just is!

But I am very limited in knowledge, so I might be speaking complete nonsense.

Thanks for your reply. ^.^^

 

[Phrak]

Some claim that energy and frequency of a quanta are the same thing, in different units.
E = hf.

ref. Collective Electrodynamics, Quantum Foundations of Electromagnetism, Carver A. Mead

Planck's constant h and its radian equivalent h_bar = h/2pi are necessary for merely historical reasons--when our standard units were defined, it was not yet known that energy and frequency [were] the same quantity.​

 

[bp_psy]

Surely it is not a simple question, we don't understand the concept as much as we think that we do.

We know almost all there is to be known about energy from the previous definition.You think there has to be more to it. It's up to you to point to us what you think that thing might be.

 

[Nano-Passion]

Perhaps the question "What really IS energy" is too broad.

Let me ask this: How does energy interact with space? I don't really understand it.

Einstein says that gravitational energy interacts with space by bending it. What about all of the other types of energies? What is really going on under our eyes? I don't believe we understand it all, in fact, it would be very foolish to say so. And that was the statement I was trying to make russ watters.

 

[Nano-Passion]

We know almost all there is to be known about energy from the previous definition.You think there has to be more to it. It's up to you to point to us what you think that thing might be.

For example how does electrical energy interact with space? What about heat?

From what I know, heat can make atoms jiggle more out of their molecular position for instance.

So does this mean heat excites the fabric of space in some way?

 

[russ_watters]

But I am very limited in knowledge, so I might be speaking complete nonsense.

Yes, you are. Let's try it another way. This is a dramatization and not exactly how the history went:

If you push an object with 9.8 N of force for 1 meter, that's 9.8 N-m. A very long time ago, someone realized that this was a useful calculation to make and gave the result a name: "work"

Someone else figured out that if that object isn't constrained by friction it will accelerate and you can use the final velocity to calculate how much work was expended to bring it up to that speed. This is useful, so the result of that calculation was given a name: "vis viva".

If you lift a 1kg object 1m, you exert 9.8 N of force over a distance of 1m. Or 9.8 N-m. A very long time ago, someone realized that this was a useful thing to know and gave it a name: "potential energy"

The people who developed these equations and concepts realized that they were all related to each other by the math they were doing. So they called them all different types of "energy". The name for energy of motion was then changed from "vis viva" to "kinetic energy"'. Ultimately though, if they had called it "Isaac's useful quantity" it would still work the same.

 

[russ_watters]

Let me ask this: How does energy interact with space? I don't really understand it.

[edit] Ehh - not exactly. Energy and mass are equivalent, so increasing the energy of an object increases its mass, which makes it interact more with space.

But energy is not a thing so it doesn't interact with space itself.

Einstein says that gravitational energy interacts with space by bending it.

No, gravitational energy is a consequence the bending of space.

From what I know, heat can make atoms jiggle more out of their molecular position for instance.

Correct.

So does this mean heat excites the fabric of space in some way?

No.

 

[Nano-Passion]

Energy does not interact with space. No, he doesn't. Gravitational energy is a consequence the bending of space.

You probably know much more than me, but for the sake of learning something new, bear with me in the argument.

To my knowledge, everything needs a medium in order to travel. Such as sound energy (requires air in space) or light energy.

How could energy travel from point A to point B if there was no space? In the way that energy travels through space, means that it does indeed interact with it.

Maybe gravitational energy is the consequence of the space bending, but mass energy is what causes the space to bend. Mass creates gravitational energy.

Yes, you are. Let's try it another way. This is a dramatization and not exactly how the history went:

If you push an object with 9.8 N of force for 1 meter, that's 9.8 N-m. A very long time ago, someone realized that this was a useful calculation to make and gave the result a name: "work"

Someone else figured out that if that object isn't constrained by friction it will accelerate and you can use the final velocity to calculate how much work was expended to bring it up to that speed. This is useful, so the result of that calculation was given a name: "vis viva".

If you lift a 1kg object 1m, you exert 9.8 N of force over a distance of 1m. Or 9.8 N-m. A very long time ago, someone realized that this was a useful thing to know and gave it a name: "potential energy"

The people who developed these equations and concepts realized that they were all related to each other by the math they were doing. So they called them all different types of "energy". The name for energy of motion was then changed from "vis viva" to "kinetic energy"'. Ultimately though, if they had called it "Isaac's useful quantity" it would still work the same.

Wow thanks. Very concise explanation.

Love your pictures in your blog too, best of luck.

No.

I am not trying to agree with the current view of energy, but rather challenge and improve it (though as limited as my current knowledge is). Of course I do not have mathematical proof (or the ability of making one at this point of my education) but I can start by making small speculations.

Which is why I speculated that heat energy may excite the fabric of space. Not out of arrogance, but for people to scrutinize my statement and point faults in its' logic.

 

[Phrak]

Russ. I don't believe you are doing the question justice invoking Newtonian mechanics and leaving out de Broglie and Einstein.

Though the conclusions one can obtain from de Broglie and Einstein are seemingly incompatible, through Newton's gravitational constant, energy--actually energy density, can be seen equivalent to a particular second derivative of the space-time metric.

 

[wrongusername]

This seems unrelated to what Nano-Passion is asking, but I am wondering how energy ties in with mass. If energy and mass could be converted into each other, then are the two somehow perhaps two sides to the same coin?

 

[Phrak]

This seems unrelated to what Nano-Passion is asking, but I am wondering how energy ties in with mass. If energy and mass could be converted into each other, then are the two somehow perhaps two sides to the same coin?

Energy is Not converted into mass, nor the converse. These are two different ways of measuring the same thing. But, good work. You have unwittingly brought up a third equivalence, I shamefully left out: energy is mass via the equation E=mc².

(Of course, the quantum field theorist will insist on regauging everything that comes to mind and could propose that E=mc² + A, such that dE=d(mc²).)

 

[K^2]

[edit] Ehh - not exactly. Energy and mass are equivalent, so increasing the energy of an object increases its mass, which makes it interact more with space.

But energy is not a thing so it doesn't interact with space itself.

That is absolutely wrong. The object that goes into Einstein Field Equation is the energy-stress tensor. Mass is a scalar quantity. You cannot make a claim that mass is what defines the curvature, because given only the mass density you cannot determine the curvature of space-time. Ergo, it is not the direct cause.

Energy, by itself, isn't it either. It is all possible 4-momentum densities in all possible coordinate systems. Thanks to transformations being linear, it is merely a tensor, rather than some crazy vector functional.Edit: Please keep in mind differences between rest mass, relativistic mass, inertial mass, and gravitational mass. Not all of them are equivalent. When the word "mass" is used by itself, it usually means rest mass, and that means the equation E=mc² isn't even generally true.

 

[Phrak]

That is absolutely wrong. The object that goes into Einstein Field Equation is the energy-stress tensor. Mass is a scalar quantity. You cannot make a claim that mass is what defines the curvature, because given only the mass density you cannot determine the curvature of space-time. Ergo, it is not the direct cause

What are you talking about? Russ made no such claim dispensing-with other terms of the stress-energy tensor whatsoever. He may be off on a few points but never claimed that mass/energy was the sole contribution to the stress-energy tensor as you say.

 

[Nano-Passion]

Energy is Not converted into mass, nor the converse. These are two different ways of measuring the same thing. But, good work. You have unwittingly brought up a third equivalence, I shamefully left out: energy is mass via the equation E=mc².

(Of course, the quantum field theorist will insist on regauging everything that comes to mind and could propose that E=mc² + A, such that dE=d(mc²).)

Hmm, interesting but confused; well from what I understand, mass in its own existence is equal to energy because when it is destroyed it releases energy thus the law of conversation.

So the destruction of an atom isn't energy because of the atom being destroyed, but the forces that keep it together?

That is absolutely wrong. The object that goes into Einstein Field Equation is the energy-stress tensor. Mass is a scalar quantity. You cannot make a claim that mass is what defines the curvature, because given only the mass density you cannot determine the curvature of space-time. Ergo, it is not the direct cause.

Edit: Please keep in mind differences between rest mass, relativistic mass, inertial mass, and gravitational mass. Not all of them are equivalent. When the word "mass" is used by itself, it usually means rest mass, and that means the equation E=mc² isn't even generally true.

If mass isn't the direct cause of the curvature of space-time then what is?

Hmm.. very interesting that the masses aren't the same. I was aware that mass is different at rest or in motion, but I wasn't aware that gravitational mass is different. How is it so?

 

[Dale]

So does this mean heat excites the fabric of space in some way?

Anything which affects the stress-energy tensor will curve spacetime.

http://en.wikipedia.org/wiki/Einstein_field_equations
http://en.wikipedia.org/wiki/Stress-energy_tensor

Your terminology "excites the fabric of space" makes me uncomfortable. In any case I agree with russ wrt the definition of energy. Once a quantity is defined that is what it "really, truly is". Once you have defined a quantity you can then use that definition to determine how it relates to other quantities but that doesn't change what it is, by definition.

 

[Nano-Passion]

Anything which affects the stress-energy tensor will curve spacetime.

http://en.wikipedia.org/wiki/Einstein_field_equations
http://en.wikipedia.org/wiki/Stress-energy_tensor

Your terminology "excites the fabric of space" makes me uncomfortable. In any case I agree with russ wrt the definition of energy. Once a quantity is defined that is what it "really, truly is".

Lmao, I apologize for the terminology.

I don't really understand the stress-energy tensor, but I am reading a book about Einstein's statements so I have some catching up to do.

So basically heat energy "stresses" space-time in a way that excites the atoms to move out of position?

 

[Dale]

So basically heat energy "stresses" space-time in a way that excites the atoms to move out of position?

What are you talking about? Atoms in an ideal gas at >0K are already constantly moving.

 

[cbetanco]

Post edited 12/29/10.

From the scientific point of view not philosophical.. Do we really understand what energy is else than a simplistic definition of its existence?

I believe from a modern understanding (I may be wrong, but this is how I learned it) the energy of a system is what give it a time dependence. That is, to move something from "now" to "later" you must give it some energy. An analogy would be with momentum. In order to move something from "here" to "over there", you must give it some momentum (that is it must have motion to get from point A to point B). Einstein unifies space and time, momentum and energy. So since time and space are unifies, one can think of energy as the time component of momentum. We refer to this unified 4-momentum (1 time component, 3 spatial) as being the generators of space-time translations. That is, to move something from "here and now" to "over there and later", you must give something both momentum and energy.

To summarize, ordinary space momentum is the measure motion between spatially separated points (here and over there), and energy is like momentum in time, that is Energy is the measure of motion between to temporally separated points (now and later)

Hope this makes sense

 

[russ_watters]

I am not trying to agree with the current view of energy, but rather challenge and improve it (though as limited as my current knowledge is). Of course I do not have mathematical proof (or the ability of making one at this point of my education) but I can start by making small speculations.

Which is why I speculated that heat energy may excite the fabric of space. Not out of arrogance, but for people to scrutinize my statement and point faults in its' logic.

The problem with this approach is that your understanding of energy is very thin, so it is counterproductive to speculate on your own. You're much better off learning what is already known.

 

[russ_watters]

Russ. I don't believe you are doing the question justice invoking Newtonian mechanics and leaving out de Broglie and Einstein.

Though the conclusions one can obtain from de Broglie and Einstein are seemingly incompatible, through Newton's gravitational constant, energy--actually energy density, can be seen equivalent to a particular second derivative of the space-time metric.

Honestly, my own understanding of energy doesn't go very far beyond Newton, so if I left out or glossed over (or erred!) on some of that, I apologize. The conversation moved quickly and based on the level of the original question I'm not sure if this might be doing more harm than good. For most of the energy transfers most people deal with on an everyday basis, those considerations are too insignificant to matter.

 

[Nano-Passion]

I believe from a modern understanding (I may be wrong, but this is how I learned it) the energy of a system is what give it a time dependence. That is, to move something from "now" to "later" you must give it some energy. An analogy would be with momentum. In order to move something from "here" to "over there", you must give it some momentum (that is it must have motion to get from point A to point B). Einstein unifies space and time, momentum and energy. So since time and space are unifies, one can think of energy as the time component of momentum. We refer to this unified 4-momentum (1 time component, 3 spatial) as being the generators of space-time translations. That is, to move something from "here and now" to "over there and later", you must give something both momentum and energy.

To summarize, ordinary space momentum is the measure motion between spatially separated points (here and over there), and energy is like momentum in time, that is Energy is the measure of motion between to temporally separated points (now and later)

Hope this makes sense

Wow, thanks.

Honestly, my own understanding of energy doesn't go very far beyond Newton, so if I left out or glossed over (or erred!) on some of that, I apologize. The conversation moved quickly and based on the level of the original question I'm not sure if this might be doing more harm than good. For most of the energy transfers most people deal with on an everyday basis, those considerations are too insignificant to matter.

I don't believe anything is too insignificant to matter. A thousand years ago people could have argued that the little moving "angels" in the sky were too insignificant to matter.

Basically what I mean is, every question can ultimately lead to more knowledge in physics.

So now I'm under the statement that mass energy curves space-time. Correct?

Then what about Electrical energy? How does it interact with space?

The problem with this approach is that your understanding of energy is very thin, so it is counterproductive to speculate on your own. You're much better off learning what is already known.

But simply learning what is already known can be counterproductive to your imagination (if you just follow all text blatantly and faithfully). I may be wasting my time (and I apologize if I might be wasting yours), but along the way I am taking advantage of my lack of knowledge to write down ideas (not here, on my notebook)...which may be valuable when I do have all of the knowledge that I need.

That is to say, I am also learning at the moment; though I only took a physics class (classical mechanics pretty much) I am educating myself at the moment by reading books till I take the next class (can't wait =D).

What are you talking about? Atoms in an ideal gas at >0K are already constantly moving.

What I was talking about was the relation of heat energy and atoms.

Atoms in an ideal gas at =0K (likely impossible) do not move at all, therefore they have no heat energy. And if they don't move at all, they also have no time sort of speak, I would guess according to relativity.

 

[Dale]

What I was talking about was the relation of heat energy and atoms.

Atoms in an ideal gas at =0K (likely impossible) do not move at all, therefore they have no heat energy.

Yes. But they still have energy (mass) and therefore they still curve spacetime.

 

[wrongusername]

Energy is Not converted into mass, nor the converse. These are two different ways of measuring the same thing. But, good work. You have unwittingly brought up a third equivalence, I shamefully left out: energy is mass via the equation E=mc².

(Of course, the quantum field theorist will insist on regauging everything that comes to mind and could propose that E=mc² + A, such that dE=d(mc²).)

Really? Then are all the physics problems I did where two particles moving at relativistic speeds towards each other collide, and a third particle is formed with the energy E = mc^2 of its mass equal to the kinetic energies of the other two particles, pure fantasy? Interesting, I thought my homework problems would at least reflect reality somewhat

But then, if one cannot be turned into the other, how can the two be connected?

 

[Phrak]

Honestly, my own understanding of energy doesn't go very far beyond Newton, so if I left out or glossed over (or erred!) on some of that, I apologize. The conversation moved quickly and based on the level of the original question I'm not sure if this might be doing more harm than good. For most of the energy transfers most people deal with on an everyday basis, those considerations are too insignificant to matter.

I'm not at all sure what this General Physics Folder is for, if not to care for subjects that don't fit well into any other folder. No need to apologize. I don't know at what level questions should be answered either. So it seemed to me, the OP asks how energy should be considered to be defined in more fundamentally terms.

 

[Nano-Passion]

Guys, somehow my main question got sidetracked. Gravitational energy or mass energy bends space. I would like to know how the different types of energy interact with space itself. For instance, how does electric energy interact with space?

I feel that there is something more to it then what is just blatantly told in textbooks.

Yes. But they still have energy (mass) and therefore they still curve spacetime.

Yes, I know, I think we have something confused. I was just talking about if heat energy is just space itself vibrating (crazy speculation).

 

[Phrak]

Guys, somehow my main question got sidetracked.

What is your main question as you would now put it?

 

[Nano-Passion]

What is your main question as you would now put it?

How the different types of energy interact with space itself. For instance, how does electric energy interact with space?

^^ =]

 

[Dale]

All forms of energy interact with the spacetime curvature tensor per the Einstein field equation. They all contribute to the stress-energy tensor so they are all related to the curvature.

 

[Relay]

I share Nano-Passion's confusion. Yes, energy is the ability to do work. But how is that work actually done. We see work being done by changes in matter. Parameters of matter such as shape, motion, temperture and densisty all change in response to energy. Something as simple a two objects in a collision stops being simple once you ask why does the collision work as it does? The question makes sense to me, however I have no answer.

 

[russ_watters]

The mechanics of a collisions are very complicated, but that's not because energy is complicated. Any collision beyond assumed ideal objects gets complicated because they deal with complex structures and properties of materials.