1. Originally Posted by Robittybob1
So we've got the nucleus - we know the mass of that.
We know the mass of a free unbound electron.

We know the energy an electron gives of as it becomes bound.

In the classical particle electron would it have relativistic mass at its lowest energy level?

If there is relativistic mass this is being weighed when measuring an atom's mass.
Refer back to "The Concept of Mass" previously linked.., there is no "relativistic mass" there is just mass. Sometimes referred to as invariant mass, inertial mass, gravitational mass or rest mass. They are all the same thing and relativistic mass is a confusing and misleading description for the TOTAL energy, of an invariant mass plus any kinetic energy associated with its velocity.

While E is generally used to denote total energy, the total energy it refers to is defined by the context it is used. In the equation E = mc^2, it referrs only to the total energy associated with a specific invariant mass. It does not include any energy associated with acceleration or velocity.

2. Originally Posted by OnlyMe
Refer back to "The Concept of Mass" previously linked.., there is no "relativistic mass" there is just mass. Sometimes referred to as invariant mass, inertial mass, gravitational mass or rest mass. They are all the same thing and relativistic mass is a confusing and misleading description for the TOTAL energy, of an invariant mass plus any kinetic energy associated with its velocity.

While E is generally used to denote total energy, the total energy it refers to is defined by the context it is used. In the equation E = mc^2, it referrs only to the total energy associated with a specific invariant mass. It does not include any energy associated with acceleration or velocity.
But that was the thing I was leading too, you can't weigh an electron once it is motion (bound). I was thinking we might have to say it has rest mass plus Energy = hV (Planck's constant times electron wave frequecy).

3. Fireflies lose weight when emits light?

4. Originally Posted by hansda
What I understand is that in Einstein's Equation E = MC^2 ; E is the Light energy and M is rest mass (Newtonian mass) which is diminished and its kinetic energy is converted into light energy .
No, E refers to the TOTAL ENERGY of the invariant mass m.

Originally Posted by hansda
As this equation was deduced from SR , which is only caused by non-zero mass at a relativistic speed . This M is a non-zero mass . Particle photon does not cause SR . So, in the case of photon E = pc only should be considered .
I do not completely understand what you are saying here.., however, "I think" you are confusing the equation $E = mc^2$, with $E = \frac{mc^2}{\sqrt{1-v^2/c^2}}$. These are two different equations and E represents a different total energy in each. E in the first equation is defined above. In the second equation E represents the total energy associated with both an invariant mass and any energy associated with its velocity. It is a misinterpretation or perhaps old and misleading interpretation of this second formula that often leads these discussions "down the rabbit hole".

As others have tried to point out there are other ways to mathematically describe both, but they involve an understanding of math that I think is beyond the discussion here.

5. Originally Posted by Emil
Fireflies lose weight when emits light?
That was really good! You got me laughing and almost choking.

Theoretically, yes. But I don't believe we have scales than can measure the loss.

6. Originally Posted by Emil
Fireflies lose weight when emits light?
Yes but it might gain mass when it flies at the speed of light.

7. .

Hi guys.

I'm trying to review the K-capture process (where one electron from the K-shell is absorbed by a proton in a nucleus and an electron from the L-shell drops down to replace the absorbed K-shell electron, emitting a photon as the replacement electron drops from the L to the K shell).

The questions which I would like to have clarified are:

- does the proton-to-neutron conversion of the electron-capturing proton increase the mass of that proton perfectlt commensurate with the mass of that electron when in its K-shell bound state?...or is the mass/energy of the newly formed neutron different by some amount (either gained or lost somehow when being captured)?

- is there any radiation/particle emitted when that capture takes place and the K-shell electron drops from a higher energy bound state (in erstwhile K-shell state) to a lower energy bound state (as part of, or otherwise now contributing to the creation of a neutron where before there was only a proton)?

- does the mass of the erstwhile L-shell electron change (decrease) perfectly commensurate with the (X-ray?) photon energy emitted when it drops from the L to the K shell?...and if so, is the now-departing X-ray just a mass which has attained lightspeed, and so being effectively 'massless' purely by dint of having attained that speed and tus all its mass is 'moving in the one direction' rather than being 'self-involved' into some sort of self-interfering state which makes its energy/mass content movement trying to go in many directions at one and so making it more 'ponderous' when part of the electron and now less ponderous because of its single-direction motion as an X-ray photon whose total energy is going in one common direction?

I am much obliged for all your inputs and to the OP/thread author. Kudos.

Your discussion is very interesting on many levels. And if anyone here can cast any light on my questions in the context of this discussion so far, I would be very grateful for any inputs related to the aspects I mentioned.

Cheers!

.

8. Rambling thoughts on the issue:
When an electron is ionized it will fly off its source molcule as a high speed electron. Which then can be slowed down probably by a magnetic field say so the excess energy over and above the electron's Rest Mass is removed.
I find it rather fascinating that from the ubiquitous electron as it reunits with the ionized atoms it can gice off photons of the exact amount to drop down through a cascade of electron energy levels. One would think there could be a reversal of the energy release process and the energy capture when the electron absorbs an electron and jumps up a level. The wave of the light is blended in with the wave path of the electron (just my primitive picture). I wonder if the momentum of the photon reflects the molecular vibratory momentum of motion at the time of release??? The direction it was going determines the direction of the photon ( How does a laser work?)

9. Originally Posted by OnlyMe
No, E refers to the TOTAL ENERGY of the invariant mass m.
What is the TOTAL ENERGY (TE) of the invariant mass (M) ?

TOTAL ENERGY (TE) = POTENTIAL ENERGY (PE) + KINETIC ENERGY(KE) .

This TOTAL ENERGY (TE) of a invariant mass (M) is constant . PE and KE changes accordingly so that TOTAL ENERGY(TE) remains constant .

In Einstein's Equation E = MC^2 ; the mass M is diminished and its PE and KE gets converted into LIGHT ENERGY . Here TOTAL ENERGY (TE) of mass (M) is converted into LIGHT ENERGY . So, this E also can be referred as LIGHT ENERGY . Here M can be either mass of electron , neutron or proton but NOT photon .

I do not completely understand what you are saying here.., however, "I think" you are confusing the equation $E = mc^2$, with $E = \frac{mc^2}{\sqrt{1-v^2/c^2}}$. These are two different equations and E represents a different total energy in each. E in the first equation is defined above. In the second equation E represents the total energy associated with both an invariant mass and any energy associated with its velocity. It is a misinterpretation or perhaps old and misleading interpretation of this second formula that often leads these discussions "down the rabbit hole".
If you refer Einstein's paper (for which you already supplied the link earlier(thank you for that link)) , Einstein used two co-ordinate system at a relative velocity . He also considered Lorentz Transformation of Energy in these two co-ordinate system to prove his Equation . These two E's as you mentioned above corresponds to the energy(E) in the two co-ordinate system . In his paper he used the terms L and L* to denote these two energies instead of E's .

As others have tried to point out there are other ways to mathematically describe both, but they involve an understanding of math that I think is beyond the discussion here.

Einstein in his paper used simple math of Lorentz Transformation , in two co-ordinate system to prove his famous equation .

His last mathematical equation in his paper is K0 − K1 = (1/2) (L/c^2)v^2 .

where H0 − E0 = K0 + C ; H1 − E1 = K1 + C .

The following is quote from Einstein's paper to understand H , E and K .

The two differences of the form H − E occurring in this expression have simple
physical significations. H and E are energy values of the same body referred
to two systems of co-ordinates which are in motion relatively to each other,
the body being at rest in one of the two systems (system (x, y, z)). Thus it is
clear that the difference H−E can differ from the kinetic energy K of the body,
with respect to the other system (, , ), only by an additive constant C, which
depends on the choice of the arbitrary additive constants of the energies H and
E. Thus we may place
H0 − E0 = K0 + C,
H1 − E1 = K1 + C,
since C does not change during the emission of light.

.
.
.

The kinetic energy of the body with respect to (, , ) diminishes as a result
of the emission of light, and the amount of diminution is independent of the
properties of the body. Moreover, the difference K0−K1, like the kinetic energy
of the electron (§ 10), depends on the velocity.
Neglecting magnitudes of fourth and higher orders we may place K0 − K1 = (1/2) (L/c^2)v^2 .

[ NOTE : In the above quote I deleted , modified some mathematical expressions for ease of copy-paste from your link of Einstein's paper .]

From the equation K0 − K1 = (1/2) (L/c^2)v^2 ; he concluded that

M = L/c^2 or L = Mc^2 .

10. Originally Posted by OnlyMe
Theoretically, yes. But I don't believe we have scales than can measure the loss.
Is the Sun or other stars loosing mass because they emit light or photon ?

Is our Earth or other planets gaining mass because they absorb light ?

What I think is that , particle photon carries Light-Energy and not Kinetic-Energy . So , absorption of a photon may increase energy-content but may not increase mass-content or inertia-content .

11. Originally Posted by hansda
Is the Sun or other stars loosing mass because they emit light or photon ?

Is our Earth or other planets gaining mass because they absorb light ?

What I think is that , particle photon carries Light-Energy and not Kinetic-Energy . So , absorption of a photon may increase energy-content but may not increase mass-content or inertia-content .
"Is the Sun or other stars loosing mass because they emit light or photon ?
" - Yes
"Is our Earth or other planets gaining mass because they absorb light" - If that was the case it would be called "Heavy " not "Light". No. because it is re-radiated away again.

12. Originally Posted by Robittybob1
"Is the Sun or other stars loosing mass because they emit light or photon ?
" - Yes
"Is our Earth or other planets gaining mass because they absorb light" - If that was the case it would be called "Heavy " not "Light". No. because it is re-radiated away again.

Do you mean to say if an electron absorbs a photon ; the mass of the electron will increase ?

13. Originally Posted by hansda
Do you mean to say if an electron absorbs a photon ; the mass of the electron will increase ?
Now that they talk of the electron cloud the whole discussion gets blurry too. So I don't know but I was thinking it must for when you think of the electron as a particle it slows down after gaining energy and the only way I think that can happen is that the mass is raised. I was going to look into this as that Photon absorption thread progresses, so I really don't know at this stage.

What is your take on this? What does the internet say? Type this question as a google search and see what sort of answers you get.
Does electron gain mass after absorbing photon?

14. Originally Posted by Robittybob1
Now that they talk of the electron cloud the whole discussion gets blurry too. So I don't know but I was thinking it must for when you think of the electron as a particle it slows down after gaining energy and the only way I think that can happen is that the mass is raised. I was going to look into this as that Photon absorption thread progresses, so I really don't know at this stage.

What is your take on this?
I think we have already discussed this issue earlier . If an electron slows down after gaining energy(kinetic energy) ; this may be a case of frame-dragging effect , which slows down the sub-atomic particle . See post number #388 .

What does the internet say? Type this question as a google search and see what sort of answers you get.
Does electron gain mass after absorbing photon?
Internet says NO . So, mass of an electron does not increase after absorbing photon , only its kinetic energy and momentum increases .

See the following sites .

1. http://astronomyonline.org/Science/Atoms.asp

15. Originally Posted by hansda
I think we have already discussed this issue earlier . If an electron slows down after gaining energy(kinetic energy) ; this may be a case of frame-dragging effect , which slows down the sub-atomic particle . See post number #388 .

Internet says NO . So, mass of an electron does not increase after absorbing photon , only its kinetic energy and momentum increases .

See the following sites .

1. http://astronomyonline.org/Science/Atoms.asp

Hansda, read the about me for the first link. It is a blog by an author who joined the military out of high school and claims his job was as an eye specialist. Not that this in itself limits his credibility, but he would likely not be able to publish even in arXiv.

The second reference seems focused more toward practical applications, chemistry etc. And the answers author is not, at least readily identified. That makes it difficult to understand the contex of the answer.

While there is some debate whether the electron itself gains mass with absorption, or the added mass is some function of the atom as a whole system is debatable, an increase of mass is the underlying principle behind the equation E = mc^2.

16. Originally Posted by OnlyMe
Hansda, read the about me for the first link. It is a blog by an author who joined the military out of high school and claims his job was as an eye specialist. Not that this in itself limits his credibility, but he would likely not be able to publish even in arXiv.
May be you are right . But can you show any reference , which says 'mass of an electron increases after absorbing photon' .

The second reference seems focused more toward practical applications, chemistry etc. And the answers author is not, at least readily identified. That makes it difficult to understand the contex of the answer.
This is a wiki site for wiki answers . So, this can be accepted as 'right' .

While there is some debate whether the electron itself gains mass with absorption, or the added mass is some function of the atom as a whole system is debatable, an increase of mass is the underlying principle behind the equation E = mc^2.
I think you are confusing with increase of relativistic-mass which slows down an electron .

It is not relativistic-mass but the effect of frame-dragging which slows down an electron .

With the absorption of photon , electron's kinetic energy and momentum increases . This increased momentum can cause frame-dragging , which in turn may slow down electron .

17. Originally Posted by hansda
May be you are right . But can you show any reference , which says 'mass of an electron increases after absorbing photon' .

This is a wiki site for wiki answers . So, this can be accepted as 'right' .

I think you are confusing with increase of relativistic-mass which slows down an electron .

It is not relativistic-mass but the effect of frame-dragging which slows down an electron .
I think I have posted both of these references earlier, but once again...

DOES THE INERTIA OF A BODY DEPEND UPON ITS ENERGY-CONTENT? this is Einstein's 1905 paper that introduces the equation E = mc^2 and its association with photon emission/absorption.

The Concept of Mass
Thus a massless photon may "transfer" nonvanishing mass. In absorbing a massless photon, ...

In the above reference, Lev Okun discusses the whole relativistic mass issue. Though when I have provided this link in the past I thought it was relatively clear and simple, I seem to be mistaken on that. You will have to think some of it through, since Okun presents both the historical view and context and the contemporay perspective. The specific quote does speak to a photon transferring mass, but not in the exact same context as we have been discussing. It still involves the electron but he describes it in the context of an object.., a cylinder....

WiKi is not always the best source of up to date information. It is both a good resource and at the same time, sometimes includes outdated concepts without discussing the contemporary view of an issue. This is the case for relativistic mass which does not exist. Mass is mass is mass. It is invariant. A particles velocity in at least the macroscopic view does not change its mass.

18. Originally Posted by OnlyMe
I think I have posted both of these references earlier, but once again...

DOES THE INERTIA OF A BODY DEPEND UPON ITS ENERGY-CONTENT? this is Einstein's 1905 paper that introduces the equation E = mc^2 and its association with photon emission/absorption.
Followings are three quotes from Einstein's paper .

1.
If a body gives off the energy L in the form of radiation, its mass diminishes
by L/c2. The fact that the energy withdrawn from the body becomes energy of
radiation evidently makes no difference, so that we are led to the more general
conclusion that
The mass of a body is a measure of its energy-content; if the energy changes
by L, the mass changes in the same sense by L/9 × 1020, the energy being
measured in ergs, and the mass in grammes.
What do you understand by the term 'energy-content' ?

Is it radiation-energy ? Total-Energy ? Potential-Energy ? Kinetic-Energy ?

2.
It is not impossible that with bodies whose energy-content is variable to a
high degree (e.g. with radium salts) the theory may be successfully put to the
test.
Radium salts may loose mass with emission of radiation but do they also gain mass with absorption of radiation ? Is it experimentally proven ?

3.
If the theory corresponds to the facts, radiation conveys inertia between the
emitting and absorbing bodies.
Here Einstein says , " If the theory corresponds to facts , ..." . He explains his theory only with emission but not with absorption . His theory is proven for emission of energy . Is his theory also proven for absorption of energy ?

The Concept of Mass
Thus a massless photon may "transfer" nonvanishing mass. In absorbing a massless photon, ...

In the above reference, Lev Okun discusses the whole relativistic mass issue. Though when I have provided this link in the past I thought it was relatively clear and simple, I seem to be mistaken on that. You will have to think some of it through, since Okun presents both the historical view and context and the contemporay perspective. The specific quote does speak to a photon transferring mass, but not in the exact same context as we have been discussing. It still involves the electron but he describes it in the context of an object.., a cylinder....

WiKi is not always the best source of up to date information. It is both a good resource and at the same time, sometimes includes outdated concepts without discussing the contemporary view of an issue. This is the case for relativistic mass which does not exist. Mass is mass is mass. It is invariant. A particles velocity in at least the macroscopic view does not change its mass.
I could not access Lev Okun's paper .

19. Originally Posted by hansda
Followings are three quotes from Einstein's paper .

1.
What do you understand by the term 'energy-content' ?

Is it radiation-energy ? Total-Energy ? Potential-Energy ? Kinetic-Energy ?

2.
Radium salts may loose mass with emission of radiation but do they also gain mass with absorption of radiation ? Is it experimentally proven ?

3.
Here Einstein says , " If the theory corresponds to facts , ..." . He explains his theory only with emission but not with absorption . His theory is proven for emission of energy . Is his theory also proven for absorption of energy ?

I could not access Lev Okun's paper .
L as used by Einstein in that paper represents the total energy associated with a specific mass, excluding any kinetic energy associated with its motion in space.

Where the radium salts issue was raised, Eimstein at the time appears to have had no knowledge that radiation associated with radium is alpha radiation, not photons. Alpha particles have mass. Remember this was 1905.

I believe Einstein actually says that mass is transferred as energy in the emission and absorption.., of energy, where the energy referred to is the photon... But I have not gone back and checked the actual wording. Positing on a device with limited memory I often lose connection with SciForums when switching to my PDF library.

20. Originally Posted by OnlyMe
L as used by Einstein in that paper represents the total energy associated with a specific mass, excluding any kinetic energy associated with its motion in space.
What do you mean by " total energy " ?

Is it mechanical energy ( potential or kinetic ) ? ... Light energy ? ... Chemical energy ? ... Nuclear energy ? or some other form of energy ? Consider the fact that there are only eight forms of energy .

What do you mean by specific mass ?

Is it " rest mass " ? ... simply mass or something else ?

Where the radium salts issue was raised, Eimstein at the time appears to have had no knowledge that radiation associated with radium is alpha radiation, not photons. Alpha particles have mass. Remember this was 1905.
Einstein mentioned radium salts as an example in his paper .

I believe Einstein actually says that mass is transferred as energy in the emission and absorption.., of energy, where the energy referred to is the photon... But I have not gone back and checked the actual wording. Positing on a device with limited memory I often lose connection with SciForums when switching to my PDF library.
Please go through Einstein's paper as you provided the link . Einstein used the word "IF" to prove his claim that , mass increases with absorbing radiation energy .

So, Einstein's this paper is not conclusive proof that , mass of an electron increases with absorbing a photon .

Now I am able to get Okun's paper .