What Constitutes Electrical Energy in an Infinite Electrical Field?

[pmb_phy]

Okay, so I've been reading about energy and no source seems to make it clear what energy really is. I understand how energy relates to objects in the real world like with moving objects and heated objects, but other forms of energy are more confusing.

Firstly, what is electrical energy? I know that electrical energy is carried in an electrical field, but what is it made of? I don't see how energy can be carried by something that isn't really real. Is it waves? If so, where do these waves come from, and where do these waves travel? If the electrical field stretches to infinity, then is the energy stored in an infinitely large place?

Also, in nuclear fission, where exactly does the energy come from? I get the whole thing about mass turning into energy, but what part of the atom turns to energy? When a neutron collides with an atom, the products have the same atomic mass as the reactants, so what mass is actually being turned into energy? It's clearly not the protons or neutrons, since those all remain with the fission products, so then is it the electrons being turned into energy?

My website may be of help on this question. See

http://www.geocities.com/physics_world/mech/what_is_energy.htm

Mass is never converted into energy. During fission or fussion what happens is that the total inertial mass (aka relativistic mass) remains constant. Only the form of mass changes. E.g. mass of potential energy changes to mass of kinetic energy. That is what people mean when they say that mass to be converted to energy.

Pete

 

[russ_watters]

Btw, no one answered this part:

When a neutron collides with an atom, the products have the same atomic mass as the reactants...

That isn't a nuclear reaction. A nuclear reaction involves splitting or combining atoms and the mass most certainly is not constant.

Okay, well, then I don't understand how work gets transferred from binding energy in an atom to heat... What happens there? Obviously, something moves from the atom to whatever is being heated, so what is being moved?

Heat energy is radiated electromagnetically: ie, light.


Again, regarding the core problem here:

I don't think that it's your fault or my fault that it's hard to understand. I'm sure we're both perfectly capable of understanding these concepts... It's just that physics is not designed to be understood by laymen like us, and people don't want to try and make it that way. I understand that and I'm not trying to insult anybody. Personally, I find it insulting the way my questions were approached in a way like, "This guy doesn't know all the stuff that I know, so I think I'll let him know that he doesn't deserve to understand."

Physics most certainly can be understood by laymen. The problem is that you are simply not accepting the knowledge people are giving you. Yes, I'm sure you are capable of understanding these concepts - you simply refuse to do so. Unless you decide to be willing to learn, you won't.

 

[rcgldr]

Energy - the capacity to do work.

It would help if an simple example were used. A battery is a good example. Batteries have "a capacity to do work". The electrical energy from a battery can be used to drive a motor, which in turn could lift an object, peforming work on the object. The amount of work done would be the weight of the object times the distance the object was raised. The battery would use up it's energy while lifting the object, until the battery no longer had any energy, and then the object would stop being lifted. If there were no losses in the system, then the amount of work done in lifting the object when it stopped moving would indicate the amount of energy that the battery had at the start.

Using real numbers, say a 12 volt battery is rated at two amp hours. Assume it's an ideal battery that outputs 12 volts independent of load and remains at 12 volts until it's energy runs out and it drops to 0 volts instantly. The battery has 24 watt hours of energy or 24x3600 = 86400 watt seconds = 86400 joules of energy. A joule is the amount of work it takes to applie a force of Newton for a distance of one meter. Gravity applies a force of 9.8 Newtons to a 1kg object, so it takes 9.8 joules of work to raise a 1kg object one meter. So this 86400 joule battery could raise a 1kg object 86400 / 9.8 ~= 8816 meters in a idealized lossless environment.

Reversing the situation, say the battery is rechargable, and the motor is replaced by a generator that charges the battery. Assuming the system is lossless, then allowing the weight to lower 8816 meters by turning the generator would generate 86400 joules of energy, recharging the battery back to it's former state.

So the 1kg object at a height of 8816 meters has 86400 joules of "potential energy", same as the 12 volt 2 amp hour battery, and both can be used to perform 86400 joules of work.

 

[pmb_phy]

Energy - the capacity to do work.

One of the reasons that Richard Feynman states that nobody knows what energy is is because a definition has yet to be found that is near what we believe energy should be defined to be. For instance, here you define "energy" as the capacity to do work. Yet the same thing can be said of both potential and kinetic energy (even mass-energy) but it is the sum of all these quantities that we call "energy" in classical mechanics.

Pete

 

[russ_watters]

I'm not sure I see your point, pete - why should different forms of energy be treated differently?

If you need to lift a 1kg object 1m, it doesn't matter from what form the energy to do that comes - whether electrical, mechanical potential or kinetic, etc., it is still just 10n-m of work.

 

[pmb_phy]

I'm not sure I see your point, pete - why should different forms of energy be treated differently?

If you need to lift a 1kg object 1m, it doesn't matter from what form the energy to do that comes - whether electrical, mechanical potential or kinetic, etc., it is still just 10n-m of work.

My point is that different forms of energy is just that, different forms of energy. It is not what energy itself is. That is an astract concept

The sum of all types of energy is the total energy (just as E = K + U = total mechanical energy) and that's what we give the name "energy". We don't call that kinetic energy nor do we call it potential energy. Its just energy. Calling it the capacity to do work one might think you were trying to define potential energy.

Richard Feynman has for a long time had a great influence on me. The topic "What is energy?" comes upin his Volume I of the Feynman Lectures.

From The Feynman Lectures on Physics - Vol. I, by Feynmann, Leighton, and Sands, page 4-2. This is also quoted on the web page I posted the URL top in my first post in this thread (which it appears you didn't read?)

It is important to realize that in physics today, we have no knowledge of what energy is. We do have a picture that mass 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 them together it all 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.

When I think of a definition for energy this is what always crosses my mind.

When it comes to "The capacity to do work" - This is the definition of potential energy as given in Classical Dynamics of Particles & Systems - 3rd Ed., Marion and Thornton, Harcourt-Brace-Jovanovich, (1988)

Pete

 

[leright]

My point is that different forms of energy is just that, different forms of energy. It is not what energy itself is. That is an astract concept

The sum of all types of energy is the total energy (just as E = K + U = total mechanical energy) and that's what we give the name "energy". We don't call that kinetic energy nor do we call it potential energy. Its just energy. Calling it the capacity to do work one might think you were trying to define potential energy.

Richard Feynman has for a long time had a great influence on me. The topic "What is energy?" comes upin his Volume I of the Feynman Lectures.

From The Feynman Lectures on Physics - Vol. I, by Feynmann, Leighton, and Sands, page 4-2. This is also quoted on the web page I posted the URL top in my first post in this thread (which it appears you didn't read?)

When I think of a definition for energy this is what always crosses my mind.

When it comes to "The capacity to do work" - This is the definition of potential energy as given in Classical Dynamics of Particles & Systems - 3rd Ed., Marion and Thornton, Harcourt-Brace-Jovanovich, (1988)

Pete

Even kinetic energy has the capacity to do work, pete. If a ball with 5 joules of KE collides elastically with a second ball at rest, and all of the first ball's KE is transferred to the second ball, then 5 joules of work has also been done on the second ball.

If we are dealing with inelastic collisions then the 'missing KE' shows up as heat, sound, or PE. And really, heat and sound are just forms of KE.

 

[rcgldr]

Although some forms of energy are relative to a frame of reference, such as gravitational potential energy and kinetic energy, the example I used, a battery, has an energy capacity that isn't sensitive to a frame of refernce. Also I'm assumed that the OP wanted a simple explanation.

 

[pmb_phy]

Even kinetic energy has the capacity to do work, pete.

Thanks. I'm well aware of that. In fact I mentioned that in the firste draft of this post but decided that it was already known to the reader. If "The capacity to do work" is (total) "energy" and kinetic energy is "The capacity to do work" and potential energy is "The capacity to do work" then potential energy = kinetic energy = (total) energy. kinetic energy and kinetic energies are forms of energy. Take, for instance, what would happen if we were to attempt to difine life. How would you do that? Would you say that any bilogical entity that walks on two legs is alive, it really doesn't get you closer to finding out what life is. You can give us numerable examples of life and yet we'd have no definition of it. This same idea also applies to energy

Pete

 

[TuviaDaCat]

if its mechanics were talking about:
isnt energy a mathematical term?
we have just derived by the laws of Newton a quantity which is constant: E=KE+PE, and it helps finding more easily more interesting characteristics of a body, such as speed.

 

[rewebster]

One of the reasons that Richard Feynman states that nobody knows what energy is is because a definition has yet to be found that is near what we believe energy should be defined to be. For instance, here you define "energy" as the capacity to do work. Yet the same thing can be said of both potential and kinetic energy (even mass-energy) but it is the sum of all these quantities that we call "energy" in classical mechanics.

Pete

This is sort of the way I look at it, but I'll go a step in a different direction:

If you're an APPLIED physicist (most researchers, some teachers, most engineers, etc.), just about all or everything you want to know about energy is there/known to be utilized--a formula for every need.

However, if you are more interested in the fundamental, theoretical aspects of energy, it is full of unknowns. This is why there isn't a viable TOE, GUT, UFT, or whatever line (theory base) you want to adhere, to call it a theory of it all to answer the question. That's why there's so many competing theories right now, and why they need different 'addendums (addendi ?)' to work on different 'things' and 'levels'/'sizes' to work 'more' accurately with the different theories.

It more or less depends on what you want to do with your 'energy'.

 

[pmb_phy]

if its mechanics were talking about:
isnt energy a mathematical term?

Yes, as is most, if not all, of the energy forms that I know of.

Pete

 

[leright]

Thanks. I'm well aware of that. In fact I mentioned that in the firste draft of this post but decided that it was already known to the reader. If "The capacity to do work" is (total) "energy" and kinetic energy is "The capacity to do work" and potential energy is "The capacity to do work" then potential energy = kinetic energy = (total) energy. kinetic energy and kinetic energies are forms of energy. Take, for instance, what would happen if we were to attempt to difine life. How would you do that? Would you say that any bilogical entity that walks on two legs is alive, it really doesn't get you closer to finding out what life is. You can give us numerable examples of life and yet we'd have no definition of it. This same idea also applies to energy

Pete

no, 'energy' is the capacity to do work, and it can have kinetic and potential energy components. PART of the capacity to do work is due to kinetic energy and PART is due to potential energy. The fact of the matter is, all energy, regardless of its form, has the capacity to do work. 5 J of energy, no matter its form, can do 5 J of work. Thus, it is possible to simply say 'energy is the capacity to do work'.

At least this is how I understood it. If an object has 5 J of PE and 5 J of KE then it has 10 J of total energy and therefore it can do 10 J of work on another object.

 

[pmb_phy]

no, 'energy' is the capacity to do work, [./quote]Is there a reason you need to repeat this to me? It was this "definition" that I was disagreeing with. As far as that goes its impossible to logiocally say that I'm wrong since we're arguing definition. At best (and more polite) way to approach your response the logical way is to disagree with me.

How would you explain that while this work is being done that the energy itself never changes.

Its okay if you want to define it that way. I choose differently. Why? Because Feynman response to the question "What is energy?" is perfectly reasonable to me and is better phrased than anything I've ever seen.

I posted only a very small summation of that section in the Feynman Lecutress V-II. I recommend that you find a copy and read his entire explanation for his answer. I posted only his answer, not his reasoning for it.

As far as "Energy is the capacity to do work" - why do you think Marion and Thornton defined potential energy as the "capacity to do work"??

I understand what you hold the definition to be and its been stated manyt times in this thread. I'm not nuts you know.:rofl: I did understand your point. I just happen to strongly disagree with it for very strong reasons. So there is no need to further state "Energy is the capacity to do work."

Pete

 

[Cyrus]

But pete, energy is the capacity to do work! :tongue2:

 

[leright]

But pete, energy is the capacity to do work! :tongue2:

:rofl::rofl:

Well, whatever. I am not interested in continuing this discussion. I don't go into the general discussion forum to discuss physics anyways. :tongue:

edit: oh, this wasn't even in general discussion...my bad...well, I still don't want to discuss it right now.

 

[leright]

How would you explain that while this work is being done that the energy itself never changes.


Pete

The energy does change...work is simply the transfer of energy from one type to another.

I will just say that energy is an abstract concept...a mathematical construct used for bookkeeping...that is all.

 

[Rutherford]

Okay. I found some of y'alls more recent answers to be more helpful than the first few. And since you guys clearly aren't going to let this thread die, I guess I'll ask a more specific question.

When a fission reaction occurs, let's say it's a neutron colliding with a U-235 atom, kay?

Okay, so there's the U-235 atom with 92 protons and 143 neutrons. So then a neutron comes in an splits the atom, right? So now there are 92 protons and 144 neutrons. So then maybe the U-235 (which is now sort of a U-236) splits into a Kr-92 and a Br-141 and releases three neutrons plus energy.

So it has the same number of protons and the same number of neutrons in the end as it had in the beginning. Except that energy is somehow released. So my question is where does this energy come from? If none of the protons or neutrons are turned into energy or however you want to say it, then what is?!

 

[Cyrus]

http://en.wikipedia.org/wiki/Nuclear_fission

 

[pmb_phy]

I will just say that energy is an abstract concept...a mathematical construct used for bookkeeping...that is all.

That is almost exactly how Feynman put it.

Pete

 

[Xile]

Energy is used loosely, because every physical thing has energy. Mass energy, anything that's moving has more energy then something that's not. E=mc^2 even the great einstein himself saw it, energy is directly proportional to mass, they are one in the same. Although it does take quite a lot of force to convert mass into energy it can be done - but in general, every physical thing has mass-energy.

So, what is energy? Energy in one thing is related to 1.its mass and 2. its momentum, because einsteins 't-shirt equation' isn't E=mc^2, it is actually E^2=m^2c^4+p^2c^2 where p is momentum and E is energy-mass. The t-shirt equation is only used when the matter is not moving (ie p=0) and we call the E the rest-energy.

So to sum up - energy and mass are one of the same thing, energy and momentum are one of the same, BUT we don't always accept this in physics, for example, Newtons laws work perfectly for building bridges, for calculating motion equations, but theyre all wrong, however they are pretty damn close, einstein goes a step further and exaplains thigns exactly, but i wouldn't use his methods to build a bridge. We use energy to define a thing with no mass, and also we use it to describe the 'thing' that causes change. Eg energy causes something to move, to stop moving, to explode etc.

 

[pmb_phy]

Energy is used loosely, because every physical thing has energy. Mass energy, anything that's moving has more energy then something that's not. E=mc^2 even the great einstein himself saw it, energy is directly proportional to mass, they are one in the same.

I disagree. I believe it was the year after Einstein published his 1905 paper on E = mc^2 that he published another paper which shows that this relation is only true in certain special cases such as that of a closed system. E.g. it fails on a roid under stress.

For derivation please see

http://www.geocities.com/physics_world/sr/inertial_energy_vs_mass.htm

Pete

 

[rewebster]

Okay. I found some of y'alls more recent answers to be more helpful than the first few. And since you guys clearly aren't going to let this thread die, I guess I'll ask a more specific question...


...So it has the same number of protons and the same number of neutrons in the end as it had in the beginning. Except that energy is somehow released. So my question is where does this energy come from? If none of the protons or neutrons are turned into energy or however you want to say it, then what is?!

One of the problems with a question such as "What is energy?" is that 'energy' is a broad based term:


http://en.wikipedia.org/wiki/Energy_(disambiguation)


And if you just want to 'relate' it to science/physics, it is STILL broad based:

http://en.wikipedia.org/wiki/Energy#Forms_of_energy


http://en.wikipedia.org/wiki/Energy_(natural_science)


3 Regarding applications* of the concept of energy
3.1 Energy transfer
3.2 Energy and the laws of motion
3.3 The Hamiltonian
3.4 The Lagrangian
3.5 Energy and thermodynamics
3.6 Equipartition of energy
3.7 Oscillators, phonons, and photons
3.8 Work and virtual work
3.9 Quantum mechanics
3.10 Relativity

*Notice the terms 'applications' and 'concept'


and:


5 Forms* of energy
5.1 Potential energy
5.1.1 Gravitational potential energy
5.1.2 Elastic potential energy
5.2 Kinetic energy
5.3 Thermal energy
5.4 Electrical energy
5.4.1 Magnetic energy
5.4.2 Electromagnetic fields
5.5 Chemical energy
5.6 Nuclear energy


Notice the term 'forms' and how many there are.


And from:


http://en.wikipedia.org/wiki/List_of_energy_topics


"This is a list of energy topics which identifies articles and categories that relate to energy. In general, the energy refers to "the potential for causing changes". The word is used in several different contexts. The engineering use has a precise, well-defined meaning, whilst many non-technical uses often do not. In science and physics, it's a physical system's capacity to do work and this page contains items that are related to that definition."


AND:

http://en.wikipedia.org/wiki/History_of_energy



During a 1961 lecture[6] for undergraduate students at the California Institute of Technology, Richard Feynman, a celebrated physics teacher and Nobel Laureate, said this about the concept of energy:

“ There is a fact, or if you wish, a law, governing natural phenomena that are known to date. There is no known exception to this law—it is exact so far we know. The law is called conservation of energy; it states that there is a certain quantity, which we call energy that does not change in 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 anything 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. ”
—The Feynman Lectures on Physics[6]


So, for right now, it depends --some things about 'energy' are definable and other things aren't.

 

[leright]

Well, the way the KE and PE expressions are DEFINED due to electrostatic or gravitational potential is in terms of WORK. If an object has 5 joules of potential energy, that means the object can do 5 joules of work and if an object has 5 joules of kinetic energy that simply means if it came to a stop (perhaps due to a collision with another object) it does 5 joules of work to the other object.

This is how the mathematics are formulated.

 

[Cyrus]

Well, the way the KE and PE expressions are DEFINED due to electrostatic or gravitational potential is in terms of WORK. If an object has 5 joules of potential energy, that means the object can do 5 joules of work and if an object has 5 joules of kinetic energy that simply means if it came to a stop (perhaps due to a collision with another object) it does 5 joules of work to the other object.

This is how the mathematics are formulated.

You keep saying this, but I think everyone your talking to already knows this and is past freshman physics.

 

[leright]

You keep saying this, but I think everyone your talking to already knows this and is past freshman physics.

Well, that is the answer Cyrus. If they don't want to except the answer and insist on a deeper understanding then they are wasting their time.

Evidently some people do not understand the definition I am giving them and insist on thinking that the definition only applies to potential energy. Everyone understands work, and all of the energy equations are DERIVED with the idea that energy is the capacity to do work!

I'm not sure what the problem is here...

 

[Rutherford]

Well, how exactly does mass relate to energy in a non-mathematical way? I know that e=mc^2 and all that, but how does this mass get used as energy? And what happens to the mass after that?

 

[rewebster]

Well, how exactly does mass relate to energy in a non-mathematical way? I know that e=mc^2 and all that, but how does this mass get used as energy? And what happens to the mass after that?

Rephrase/paraphrase the question(s)----its not specific enough as it is.(please)



(for me, anyway--)

 

[pmb_phy]

Well, how exactly does mass relate to energy in a non-mathematical way? I know that e=mc^2 and all that, but how does this mass get used as energy? And what happens to the mass after that?

The energy is conserved. Some of it is locked up in mass-energy. This means that the forms of energy can change. So when a nuleus of an atom splits there is an increase in the total kinetic energy of the particles released. Also, when Einstein derived that equation for the first time he used "m" to refer to porper mass. He started out having the body release ennergy. He then showed that the release in energy came with a decrease in the proper mass of the emitting body. The amount of energy radiated E caused a decrease in proper mass of delta m. So delta E = delta mc^2.

That is the meaning of the equation. If you like I can show a website (mine of course) where I post several derivations of this relation. I ask first bercause it appears to me that people rarely read the references.

Pete

 

[marcus]

The thing is, we're talking about elementary particles here. Perhaps energy is the most elementary of all particles. Indeed, E does equal mc^2. Mass is energy. At some point, you can't ask what something is made of. It just is. You have atoms, which are made of nucleons and electrons, which are made ...

there is a paper by Laurent Freidel and Aristide Baratin
that illustrates a current direction in research examining the possibility that matter can be a facet of spacetime geometry

the thing is to get a dynamical model of the geometry
if it is a good model (like their spinfoam model tries to be) then it will contain matter fields (Feynman diagrams) which will appear out of the foam as you gradually turn gravity off.

I am not suggesting that you read the paper, which is technical. But you might like to know it (and others like it) exist.
http://arxiv.org/abs/hep-th/0611042
Hidden Quantum Gravity in 4d Feynman diagrams: Emergence of spin foams
Aristide Baratin, Laurent Freidel
28 pages
(Submitted on 3 Nov 2006, last revised 28 Mar 2007)

"We show how Feynman amplitudes of standard QFT on flat and homogeneous space can naturally be recast as the evaluation of observables for a specific spin foam model, which provides dynamics for the background geometry. We identify the symmetries of this Feynman graph spin foam model and give the gauge-fixing prescriptions. We also show that the gauge-fixed partition function is invariant under Pachner moves of the triangulation, and thus defines an invariant of four-dimensional manifolds. Finally, we investigate the algebraic structure of the model, and discuss its relation with a quantization of 4d gravity in the limit where the Newton constant goes to zero."

so you might imagine matter to be facets of geometry---microscopic "kinks" or "twists" in geometry some of which will cancel each other or react with each other---and which affect the surrounding geometry in the way we associate with gravity.
then to understand gravity at small scale would mean to understand the microscopic dynamics of spacetime geometry and matter.