Does a charge gain energy in every frame when it is accelerated?

[kmarinas86]

Does a charge gain energy in every [inertial] frame when it is accelerated?

If you start with one inertial frame, and then you accelerate a charge from that inertial frame to another one, it appears that we produced a changing electric field in making that occur. Isn't the changing electric field changing according to every inertial frame? Isn't there a changing electric field even in the initial inertial frame of the charge? Wouldn't it then be true that the electron must have absorbed some of this changing electric field? Wouldn't the electron have a different inertial mass as a result, according to every inertial frame?

Also, if one were to then accelerate the charge in the other direction, wouldn't that charge lose some of the energy it had gained?

If so, does there exist an inertial frame, where if a charge matched it, it has the least work done on it, in net?

If one had two initially identical systems, whose COM frames are also identical, with 100 equal masses, all of them identical in correspondence between the two systems, is it true that in the Special Relativity or General Relativity that the first system where only 20 masses are accelerated by 1 m/s, and the other 80 not at all, have the same energy as the second system where the 80 masses (corresponding to the 80 of the first system), instead of those 20 (corresponding to the 20 of the first system), are accelerated by 1 m/s, but in the opposite direction? There remains a symmetry between the two systems. The relative velocity between the 20 masses and the 80 masses is identical between the two systems in the before and after states. If no special frame determined the energy content, then all the fields and energy densities between masses in the two systems should be the same too. Doesn't a different amount of work performed on each system violate that notion though?

 

[Naty1]

There appear to be a umber of misconceptions embodied in your question...If I am reading you correctly.

I'm not sure what you imply by "a changing electric field". The field IS different because the electron is moving versus static...but not because the field strength or electron charge is increasing in strength.

Are you implying the electric charge and field increases with velocity??
Try reading here for an explanation:

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

Note that the standard unit of kinetic energy (energy imparted to an accelerating electron) is the result of work done on the particle (in joules) times FIXED electron charge.

You can say the relativistic mass of the electron changes, which is a measure of the electron energy increase, but current terminolgoy focuses on changes in momentum istead...you can search these forums for "relativistic mass" and get numerous explanations.

...charge gain energy...according to every inertial frame?

no...not generally...depends what you mean...each given inertial frame making successive measurements will record a change in energy...

but your statement is not generally true in relativity...Every frame measurement/observation will likely result in a different measure from every other frame...a different observation...they are ALL relative. Consider, for example, a reference frame moving at the same velocity (speed and direction) as the electron...the electron will appear as at rest.

 

[kmarinas86]

There appear to be a umber of misconceptions embodied in your question...If I am reading you correctly.

I'm not sure what you imply by "a changing electric field". The field IS different because the electron is moving versus static...but not because the field strength or electron charge is increasing in strength.

Are you implying the electric charge and field increases with velocity??

I said: "If you start with one inertial frame, and then you accelerate a charge from that inertial frame to another one, it appears that we produced a changing electric field in making that occur." [Emphasis added]

What I really tried to say was this, "Say I did work, via a changing electric field, to make an electron accelerate. Isn't that fact supposed to be invariant with respect to the reference frame chosen? This scenario has the constraint that the energy comes from my changing electric field and goes to the electron. The from-goes to relationship must be preserved, and it cannot be reversed in any way. Stated another way, this scenario cannot accept that there would be frames of reference in which energy was not transferred from my changing electric field to the electron."

 

[PAllen]

I said: "If you start with one inertial frame, and then you accelerate a charge from that inertial frame to another one, it appears that we produced a changing electric field in making that occur." [Emphasis added]

What I really tried to say was this, "Say I did work, via a changing electric field, to make an electron accelerate. Isn't that fact supposed to be invariant with respect to the reference frame chosen? This scenario has the constraint that the energy comes from my changing electric field and goes to the electron. The from-goes to relationship must be preserved, and it cannot be reversed in any way. Stated another way, this scenario cannot accept that there would be frames of reference in which energy was not transferred from my changing electric field to the electron."

I don't see the issue then. Inertial frame 1: field generator accelerates charge for a bit leaving it now moving at speed v in the +x direction. Inertial frame 2: field generator accelerates charge from moving at v in the -x to stationary. In both cases, the changing field does the same work on the charge. You need to clarify what the purported issue is.

[Edit: To a first approximation, ignore energy carried by radiation, and this is not different from Newtonian dynamics. In both inertial frames, the momentum change of the field generator balances the momentum change of the charge. The kinetic energy in both frames increases (whatever power source is in the field generator loses energy equal to the work done on the charge in both frame) when change in motion of the generator is taken into account. You have to account energy and momentum of the field source. For more accuracy, you would also have to account for energy and momentum carried by radiation.]

 

[kmarinas86]

I don't see the issue then. Inertial frame 1: field generator accelerates charge for a bit leaving it now moving at speed v in the +x direction. Inertial frame 2: field generator accelerates charge from moving at v in the -x to stationary. In both cases, the changing field does the same work on the charge. You need to clarify what the purported issue is.

It seems that you agree that work is done on the charge regardless of the inertial frame chosen. So is there something in this charge that accounts for the amount of work done on it? In other words, can the amount of work done on a charge be well-defined in relativity? Does the charge store an amount of energy well-defined in its own inertial frame that is increased when work is done on it? Or does that quantity simply lack existence?

 

[PAllen]

It seems that you agree that work is done on the charge regardless of the inertial frame chosen. So is there something in this charge that accounts for the amount of work done on it? In other words, can the amount of work done on a charge be well-defined in relativity? Does the charge store an amount of energy well-defined in its own inertial frame that is increased when work is done on it? Or does that quantity simply lack existence?

Charge and field are simply the vehicle for doing work. Work is done by changing the momentum of the charge carrying body. This is straight relativistic mechanics. The EM part of it is simply Maxwells equations which are Lorentz invariant.

 

[kmarinas86]

Charge and field are simply the vehicle for doing work. Work is done by changing the momentum of the charge carrying body. This is straight relativistic mechanics. The EM part of it is simply Maxwells equations which are Lorentz invariant.

Does the charge store an amount of energy well-defined in its own inertial frame that is increased when work is done on it?

 

[Dale]

Say I did work, via a changing electric field, to make an electron accelerate. Isn't that fact supposed to be invariant with respect to the reference frame chosen? This scenario has the constraint that the energy comes from my changing electric field and goes to the electron. The from-goes to relationship must be preserved, and it cannot be reversed in any way. Stated another way, this scenario cannot accept that there would be frames of reference in which energy was not transferred from my changing electric field to the electron."

I am not sure this is correct. In some frames the charge will decelerate, losing energy, which would presumably go from the electron to the field.

 

[kmarinas86]

Say I did work, via a changing electric field, to make an electron accelerate. Isn't that fact supposed to be invariant with respect to the reference frame chosen? This scenario has the constraint that the energy comes from my changing electric field and goes to the electron. The from-goes to relationship must be preserved, and it cannot be reversed in any way. Stated another way, this scenario cannot accept that there would be frames of reference in which energy was not transferred from my changing electric field to the electron.

I am not sure this is correct. In some frames the charge will decelerate, losing energy, which would presumably go from the electron to the field.

My bad. I meant, inertial frame.

 

[Dale]

I also meant inertial frame. In some inertial frames the charge will decelerate, losing energy.

 

[kmarinas86]

So are there two separate ways the energy of an electron can appear to increase?

1) Lorentz boost, where we talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron?

These are not equivalent, are they?

If they are not equivalent, then doesn't item #2 imply that somehow there is a special inertial frame for the electron in which the contribution of energy from "physical acceleration of the electron" is zero? It would seem that any acceleration away from this special inertial frame, in whatever direction that may be, would add to the energy and therefore the so-called "invariant mass" of the electron, which is insensitive to Lorentz boosts.

Would different charged particles have the same such frame, or could they all differ?

 

[kmarinas86]

I also meant inertial frame. In some inertial frames the charge will decelerate, losing energy.

So in some inertial frames the energy flows in one direction, and other inertial frames it flows in the opposite direction? What happens if I simply insert a one-way mirror in between so that the energy can only complete the trip in one direction?

 

[PAllen]

Does the charge store an amount of energy well-defined in its own inertial frame that is increased when work is done on it?

No, in my example, the charge in frame 2 decelerates to no motion. Its kinetic energy and momentum go to zero. Work can decrease kinetic energy as well as increase it. In this case, the books are balanced by the the corresponding increase in momentum and kinetic energy of the field source. Again, the momentum, kinetic energy, work are all kinematics. The charge and field here enter only as the particular agents in your example. (And, for exactness, again, one would need to worry about radiation).

 

[PAllen]

So in some inertial frames the energy flows in one direction, and other inertial frames it flows in the opposite direction? What happens if I simply insert a one-way mirror in between so that the energy can only complete the trip in one direction?

A mirror won't affect electric or magnetic field. A conducting box will, but then there will be no work or energy transfer at all.

 

[Dale]

So in some inertial frames the energy flows in one direction, and other inertial frames it flows in the opposite direction? What happens if I simply insert a one-way mirror in between so that the energy can only complete the trip in one direction?

One way mirrors only work because one room is dark and the other is well lit, they don't make energy flow in one direction. I don't think that there is any material which will make energy flow in one direction in all reference frames.

 

[kmarinas86]

One way mirrors only work because one room is dark and the other is well lit, they don't make energy flow in one direction. I don't think that there is any material which will make energy flow in one direction in all reference frames.

How can the direction of energy flow be dependent on the inertial frame of reference? It's like saying that in some reference frames the car is accelerating in one direction while in others in the opposite direction when all the observers are inertial, which I would presume means that the observers are not propelled by any means whatsoever (i.e. they are moving inertially).

 

[PAllen]

How can the direction of energy flow be dependent on the inertial frame of reference? It's like saying that in some reference frames the car is accelerating in one direction while in others in the opposite directions when all the observers are inertial, which I would presume means that the observers are not propelled by any means whatsoever (i.e. they are moving inertially).

Frame 1: Car accelerates 0 to 60, East.

Frame 2, moving 60 to East relative to frame 1: Car decelerates from moving 60 West to 0.

What part of this is mysterious? Perhaps review basic Newtonian mechanics before worrying about relativity and electromagnetism.

 

[kmarinas86]

Frame 1: Car accelerates 0 to 60, East.

Frame 2, moving 60 to East relative to frame 1: Car decelerates from moving 60 West to 0.

What part of this is mysterious? Perhaps review basic Newtonian mechanics before worrying about relativity and electromagnetism.

Doesn't the energy of the remaining mass of the car (i.e. subtracting fuel losses etc.) increase when accelerated? Doesn't it actually weigh more, by a very tiny amount? Doesn't this extra mass come from some of the mass that was converted in the process of burning chemical fuel? Doesn't that extra mass become a part of the body of the car, its passengers, etc.?

 

[Dale]

How can the direction of energy flow be dependent on the inertial frame of reference? It's like saying that in some reference frames the car is accelerating in one direction while in others in the opposite direction when all the observers are inertial, which I would presume means that the observers are not propelled by any means whatsoever (i.e. they are moving inertially).

I don't get the analogy. Instead of making strange analogies why don't you work the problem out?

In this scenario there are exactly two places for the energy: the field and the electron's KE. In some frames the electron's KE goes up and therefore the field's energy must go down. In other frames the electron's KE goes down and therefore the field's energy must go up.

 

[kmarinas86]

Okay, let's forget the car analogy and return to one of my earlier posts:

So are there two separate ways the energy of an electron can appear to increase?

1) Lorentz boost, where we talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron?

These are not equivalent, are they?

If they are not equivalent, then doesn't item #2 imply that somehow there is a special inertial frame for the electron in which the contribution of energy from "physical acceleration of the electron" is zero? It would seem that any acceleration away from this special inertial frame, in whatever direction that may be, would add to the energy and therefore the so-called "invariant mass" of the electron, which is insensitive to Lorentz boosts.

Would different charged particles have the same such frame, or could they all differ?

 

[Dale]

somehow there is a special inertial frame for the electron in which the contribution of energy from "physical acceleration of the electron" is zero?

Sure, it would be the frame where the speed of the electron was the same before and after resulting in no net change in KE, only a net change in direction. That is also known as the center of momentum frame. It is a very convenient frame for many purposes.

And the center of momentum frame doesn't belong to a charge, but to a system, in this case the charge and the field.

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

 

[PAllen]

Doesn't the energy of the remaining mass of the car (i.e. subtracting fuel losses etc.) increase when accelerated? Doesn't it actually weigh more, by a very tiny amount? Doesn't this extra mass come from some of the mass that was converted in the process of burning chemical fuel? Doesn't that extra mass become a part of the body of the car, its passengers, etc.?

Frame 1: a tiny bit of mass of fuel is converted to kinetic energy of car plus kinetic energy of earth. Assuming perfect mass/energy conversion, rest mass of car goes down, total mass/energy of car goes down slightly (a little transferred to earth).

Frame2: a tiny bit of mass of fuel is converted to kinetic energy of Earth while decreasing kinetic energy of car (work done against car's motion in this frame; increase in KE of Earth minus decrease in KE of car equals energy converted from mass). Rest mass of car decreases (rest mass is invariant - all agree on it).

At this point, given the number and nature of misunderstanding, you really should review Newtonian and relativistic mechanics.

 

[kmarinas86]

Frame 1: a tiny bit of mass of fuel is converted to kinetic energy of car plus kinetic energy of earth. Assuming perfect mass/energy conversion, rest mass of car goes down, total mass/energy of car goes down slightly (a little transferred to earth).

Not all of that energy goes into the classical kinetic energy of the system (i.e. not all of it goes to (1/2)mv^2). Doesn't some of it go into reclaiming some of the loss of m in other masses, which excludes whatever is lost as in the form of heat? Doesn't mass-to-energy converted minus energy-to-mass converted give us the energy lost as heat? That heat loss is not immediately 100%, but in the long run all of that energy escapes. Until then, m of the car, the earth, etc. should have increased.

Let me focus on this part this time:

So are there two separate ways the energy of an electron can appear to increase?

1) Lorentz boost, where we talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron?

 

[PAllen]

I don't get the analogy. Instead of making strange analogies why don't you work the problem out?

In this scenario there are exactly two places for the energy: the field and the electron's KE. In some frames the electron's KE goes up and therefore the field's energy must go down. In other frames the electron's KE goes down and therefore the field's energy must go up.

Right, this is more accurate. I've been pushing the idea that for low speeds, ignore propagation delay, and figure there must be a source of the field. Then (ignoring propagation delay) you simply have kinematics between field source and 'test charge'.

 

[kmarinas86]

Two concepts:
1) Lorentz boost, where we talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron, where we are adding momentum to an electron through some external source.

How can these be physically identical? No proper acceleration of the electron is implied by the former, but the latter does entail such a thing.

 

[kmarinas86]

Right, this is more accurate. I've been pushing the idea that for low speeds, ignore propagation delay, and figure there must be a source of the field. Then (ignoring propagation delay) you simply have kinematics between field source and 'test charge'.

Let's say the field that powered the electron was actually more complicated, like a hydrocarbon fuel. Some of the energy of that fuel is lost as heat, the rest of that energy is absorbed by the electron. So the electron has more energy. Some of it goes to increase its mass, and some of it goes to increase its speed. The more energy that was already added to it, then a greater proportion will go to its mass. At relativistic speeds, only a very small bit goes into increasing its speed. Shouldn't accelerating an electron increase its mass? How is that kinematics? We are changing energy content of particles of the observed, not just varying those of an observer.

Would you say that there is an inertial frame where energy flowed from the electron to the chemical fuel? The release of energy by a fuel is defined by a chemical reaction. You don't get to reverse that chemical reaction by choosing a different inertial frame. Efficiency is less than 100% so either the losses are losses from the fuel or they are losses from the electron decelerating which supposedly recharges that fuel, and that should not change just because the observer is sitting on a different perch.

 

[PAllen]

Not all of that energy goes into the classical kinetic energy of the system (i.e. not all of it goes to (1/2)mv^2). Doesn't some of it go into reclaiming some of the loss of m in other masses, which excludes whatever is lost as in the form of heat? Doesn't mass-to-energy converted minus energy-to-mass converted give us the energy lost as heat? That heat loss is not immediately 100%, but in the long run all of that energy escapes. Until then, m of the car, the earth, etc. should have increased.

There's no need to bring heat into it, just needless complication. I said assuming perfect conversion, just for the purposes of discussing energy/momentum balance. If we are talking mass/energy conversion, of course we are not using (1/2)mv^2 but the the relativistic energy momentum formulas. Ignoring heat, what I described is correct and adequate. Anyway, if the energy generation produces heat, whatever part is lost be the car decreases its rest mass further, and increase that of the Earth (the presumed heat sink). In sum, the rest mass of the car decreases by the kinetic energy created in the car/earth system; heat flow from car to Earth simply decreases rest mass of car further (first some mass converted to heat, then heat lost, so mass of car decreases).

 

[PAllen]

Let's say the field that powered the electron was actually more complicated, like a hydrocarbon fuel. Some of the energy of that fuel is lost as heat, the rest of that energy is absorbed by the electron. So the electron has more energy. Some of it goes to increase its mass, and some of it goes to increase its speed. The more energy that was already added to it, then a greater proportion will go to its mass. At relativistic speeds, only a very small bit goes into increasing its speed. Shouldn't accelerating an electron increase its mass? How is that kinematics? We are changing energy content of particles of the observed, not just varying those of an observer.

Would you say that there is an inertial frame where energy flowed from the electron to the chemical fuel? The release of energy by a fuel is defined by a chemical reaction. You don't get to reverse that chemical reaction by choosing a different inertial frame. Efficiency is less than 100% so either the losses are losses from the fuel or they are losses from the electron decelerating which supposedly recharges that fuel, and that should not change just because the observer is sitting on a different perch.

This is getting a bit silly. The momentum gained by the electron in some particular inertial frame is balanced (modulo propagation delay) by momentum change of the generator, no matter what its nature. All the rest you describe is irrelevant.

 

[kmarinas86]

This is getting a bit silly. The momentum gained by the electron in some particular inertial frame is balanced (modulo propagation delay) by momentum change of the generator, no matter what its nature. All the rest you describe is irrelevant.

Let's have something simpler.

A charged capacitor with + and - plates, and an external electron.

The discharging of the charge capacitor is the source of our changing electric field. The external electron is affected by the discharge of - charge jumping to the + plate. Therefore, it is easy to see that some of the potential energy consumed traveled from the field source to the electron.

Now let's look at it from a frame of reference where the electron is decelerating. Remember when the one you agreed with stated this:

What I really tried to say was this, "Say I did work, via a changing electric field, to make an electron accelerate. Isn't that fact supposed to be invariant with respect to the reference frame chosen? This scenario has the constraint that the energy comes from my changing electric field and goes to the electron. The from-goes to relationship must be preserved, and it cannot be reversed in any way. Stated another way, this scenario cannot accept that there would be frames of reference in which energy was not transferred from my changing electric field to the electron."

I am not sure this is correct. In some frames the charge will decelerate, losing energy, which would presumably go from the electron to the field.

Presumably? Please explain how a decelerating charge will charge the capacitor in one frame when in a different frame the capacitor is discharged? You can't have the capacitor doing opposite things in different frames. It makes zero sense.

 

[PAllen]

Let's have something simpler.

A charged capacitor with + and - plates, and an external electron.

The discharging of the charge capacitor is the source of our changing electric field. The external electron is affected by the discharge of - charge jumping to the + plate. Therefore, it is easy to see that some of the potential energy consumed traveled from the field source to the electron.

Now let's look at it from a frame of reference where the electron is decelerating. Remember when the one you agreed with stated this:

In one frame, the capacitor discharges, emitting a propagating EM pulse (which carries momentum), the capacitor's momentum changes by the opposite of the momentum transferred to the pulse. The capacitor has lost energy as well. The pulse interacts with electron, transferring momentum to it; the pulse loses a little energy/momentum.

Now another inertial frame where the electron is initially moving and ends up at rest. The capacitor is moving in this frame. The capacitor discharges. The capacitor and pulse now add up to the same momentum as originally carried by just the capacitor; the pulse carries energy lost by the capacitor. The motion of the pulse in relation to the electron is such that it decelerates the electron, gaining energy and momentum from it. There is nothing mysterious about this - particle accelerators can be run to decelerate particles as easily as accelerate them; in such case, the energy and momentum of the particles is transferred to the e/m pulses, and then to whatever finally absorbs the pulses.

 

[kmarinas86]

In one frame, the capacitor discharges, emitting a propagating EM pulse (which carries momentum), the capacitor's momentum changes by the opposite of the momentum transferred to the pulse. The capacitor has lost energy as well. The pulse interacts with electron, transferring momentum to it; the pulse loses a little energy/momentum.

Now another inertial frame where the electron is initially moving and ends up at rest. The capacitor is moving in this frame. The capacitor discharges. The capacitor and pulse now add up to the same momentum as originally carried by just the capacitor; the pulse carries energy lost by the capacitor. The motion of the pulse in relation to the electron is such that it decelerates the electron, gaining energy and momentum from it. There is nothing mysterious about this - particle accelerators can be run to decelerate particles as easily as accelerate the; in such case, the energy and momentum of the particles is transferred to the e/m pulses, and then to whatever finally absorbs the pulses.

So is there really no difference between a:
1) Lorentz boost, where we [are] talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron, where we are adding momentum [of photons, each with some invariant mass ((p/c)=sqrt((E/c^2)^2-(p/c)^2)] through some external source[, and thereby adding to electron's energy content by some multiple of ((p/c)=sqrt((E/c^2)^2-(p/c)^2) as witnessed by all inertial frames.]

?

 

[PAllen]

So is there really no difference between a:
1) Lorentz boost, where we [are] talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron, where we are adding momentum [of photons, each with some invariant mass ((p/c)=sqrt((E/c^2)^2-(p/c)^2)] through some external source[, and thereby adding to electron's energy content by some multiple of ((p/c)=sqrt((E/c^2)^2-(p/c)^2) as witnessed by all inertial frames.]

?

No, I don't quite agree. If a charge accelerates in one inertial frame, it accelerates in all inertial frames (noting that acceleration/deceleration is just terminology for whether the acceleration is in the direction of motion or against it). Further, an actual change in the motion of charged particle produces a propagating kink in its field, a Lorentz boost does not. I don't see how any of this is related to what I said in the post you are responding to.

 

[Dale]

Two concepts:
1) Lorentz boost, where we talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron, where we are adding momentum to an electron through some external source.

How can these be physically identical? No proper acceleration of the electron is implied by the former, but the latter does entail such a thing.

Exactly. They are not identical. They are not even closely related.

 

[Dale]

Let's say the field that powered the electron was actually more complicated

When you don't understand a simple example it is a bad idea to move to a more complicated example. Even for an expert, it is always possible to make a system so complicated that the expert fails to analyze it correctly. Stick with very basic simple systems until you understand them, and only move on to more complicated systems then. You will almost never gain any insight by moving to a system more complicated than one you already don't understand.

Let's stick with the simplest system you can imagine that let's you understand. Fields are rather complicated since you have to integrate over all of space to get the energy, so perhaps you would want to use a mechanical example instead. But pick a simple one.

 

[kmarinas86]

So is there really no difference between a:
1) Lorentz boost, where we [are] talking about looking at an electron from a different inertial frame, and
2) Physical acceleration of the electron, where we are adding momentum [of photons, each with some invariant mass ((p/c)=sqrt((E/c^2)^2-(p/c)^2)] through some external source[, and thereby adding to electron's energy content by some multiple of ((p/c)=sqrt((E/c^2)^2-(p/c)^2) as witnessed by all inertial frames.]

?

No, I don't quite agree. If a charge accelerates in one inertial frame, it accelerates in all inertial frames (noting that acceleration/deceleration is just terminology for whether the acceleration is in the direction of motion or against it). Further, an actual change in the motion of charged particle produces a propagating kink in its field, a Lorentz boost does not.

What you thought was disagreement is actually a bit of agreement. I asked the above because I find it doubtful that the two could be equivalent.

In speaking of a "kink" in a field, it is known that photons are exchange particles for the electromagnetic force. If work were done on a charge, I would presume that means that a charge receives more energy from these exchange particles than it sends. The "rest mass" of the charge should therefore increase in that case. That bit should be invariant, even if some frames see it as "accelerating" the charge, while others see it as "decelerating", I think. Would that be correct?

When the opposite occurs, a electron literally gives off more energy via photons than it takes in. That would mean that its rest mass should decrease. Decrease of "rest mass" applies to atoms so why not stand-alone electrons?

While it had been said that energy flow can change directions with respect to a given reference frame, I'm not so sure how that could be possible if the energy flow itself were constrained to the speed of light, as it would be impossible to outpace that energy flow no matter how fast the observer is. There is no frame of reference in which you can observe the flow of a photon (with all of its energy and force content) going in the direction opposite of that seen in another reference frame. Thus, whether or not the electron gains a certain amount mass should be something that can be agreed upon by all inertial observers, correct? If so, that would make it contrary to the notion that, in a frame-dependent way, a charge may be seen to lose energy to changing electric field or the other way around.