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Mass and Energy

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  Mass and Energy ram@zedat.fu-berlin.de (Stefan Ram) - 2026-01-01 16:19 +0000
    Re: Mass and Energy nospam@de-ster.demon.nl (J. J. Lodder) - 2026-01-01 22:38 +0100
    Re: Mass and Energy x <x@x.net> - 2026-01-02 10:03 -0800
    Re: Mass and Energy x <x@x.net> - 2026-01-02 10:06 -0800
      Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-02 21:07 +0100
        Re: Mass and Energy x <x@x.net> - 2026-01-02 15:40 -0800
        Re: Mass and Energy x <x@x.net> - 2026-01-02 16:05 -0800
          Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-03 14:30 +0100
        Re: Mass and Energy Thomas Heger <ttt_heg@web.de> - 2026-01-04 09:06 +0100
          Re: Mass and Energy nospam@de-ster.demon.nl (J. J. Lodder) - 2026-01-04 12:28 +0100
            Re: Mass and Energy Thomas Heger <ttt_heg@web.de> - 2026-01-06 09:03 +0100
              Re: Mass and Energy nospam@de-ster.demon.nl (J. J. Lodder) - 2026-01-06 10:56 +0100
                Re: Mass and Energy Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-01-06 06:52 -0800
                  Re: Mass and Energy nospam@de-ster.demon.nl (J. J. Lodder) - 2026-01-06 16:12 +0100
    Re: Mass and Energy "Paul.B.Andersen" <relativity@paulba.no> - 2026-01-04 20:51 +0100
      Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-06 03:04 +0100
        Re: Mass and Energy "Paul.B.Andersen" <relativity@paulba.no> - 2026-01-06 22:12 +0100
          Re: Mass and Energy "Paul.B.Andersen" <relativity@paulba.no> - 2026-01-06 22:27 +0100
          Re: Mass and Energy Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-01-06 13:43 -0800
            Re: Mass and Energy Python <python@cccp.invalid> - 2026-01-06 21:46 +0000
              Re: Mass and Energy Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-01-07 04:32 -0800
          Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-06 23:27 +0100
            Re: Mass and Energy Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-01-07 04:14 -0800
            Re: Mass and Energy "Paul B. Andersen" <relativity@paulba.no> - 2026-01-07 22:18 +0100
      Re: Mass and Energy Thomas Heger <ttt_heg@web.de> - 2026-01-06 09:15 +0100
        Re: Mass and Energy "Paul.B.Andersen" <relativity@paulba.no> - 2026-01-06 22:57 +0100
          Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-06 23:51 +0100
            Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-07 05:12 +0100
              Re: Mass and Energy Maciej Woźniak <mlwozniak@wp.pl> - 2026-01-07 08:16 +0100
          Re: Mass and Energy "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-01-07 13:20 -0800
            Re: Mass and Energy "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-01-07 13:29 -0800
            Re: Mass and Energy Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-01-07 22:53 +0100

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#667977 — Mass and Energy

"Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
:that mass could be converted to energy as
:predicted by Einstein's E = mc².

  I can spot three mistakes here right off the bat.

       First, the phrase "mass could be converted to energy" is based on
  a misconception, since mass already /is/ a form of energy - there's no
  "conversion" happening. It's like saying, "water can be turned into a
  liquid" - no, water /is/ a liquid.

       Second, "E=mc^2" only applies to systems at rest. In general,
  it's "E^2=(mc^2)^2+(pc)^2", where "p" is the system's momentum. 
  (That basically says mass is the magnitude of the four-momentum.)

       Third, mass is conserved in nuclear fission. This point is often
  explained incorrectly, even in otherwise solid textbooks like Grif-
  fiths.

       I've laid out the full argument elsewhere, but here's the (suffi-
  cient) short version:

       Take a nucleus that's at rest, so its total momentum p=0.

       After fission, because momentum is conserved, the total momentum
  of all the fragments is still zero. That means the relation "E^2=(mc^2
  )^2+(pc)^2" simplifies to "E=mc^2" both before and after the split.

       Since energy is also conserved, the total energy E of the nucleus
  and its fragments - including their kinetic energy - stays the same,
  call it E. From "E=mc^2", it immediately follows: if E stays constant,
  m does too.

E_"before" = E_"after" - due to conservation of energy        (0)

E_"before" = m_"before" c^2 - as you said yourself            (1)

E_"after" = m_"after" c^2 - the same as (1), just later       (2)

m_"after" = m_"before" - substituting (1) and (2) into (0)    (3)
                         and dividing by c^2

  Only when you change what you call the "system", and treat the split 
  products separately, do you get systems with nonzero momentum and 
  find a mass defect and non-zero kinetic energies.

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#667980

Stefan Ram <ram@zedat.fu-berlin.de> wrote:

Please do not quote mine,
and please do not break threads,

Jan

> "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
> :that mass could be converted to energy as
> :predicted by Einstein's E = mc?.
> 
>   I can spot three mistakes here right off the bat.

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#667992

On 1/1/26 08:19, Stefan Ram wrote:
 > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
 > :that mass could be converted to energy as
 > :predicted by Einstein's E = mc².
 >
 >    I can spot three mistakes here right off the bat.
 >
 >         First, the phrase "mass could be converted to energy" is based on
 >    a misconception, since mass already /is/ a form of energy - there's no
 >    "conversion" happening. It's like saying, "water can be turned into a
 >    liquid" - no, water /is/ a liquid.

The basic problem is that you think that 'science' is
'automatically true' and all you have to do is say
words that sound like 'science' and they are automatically
'true' because they 'sound like science'.

For your words to have value, you must care what is true.

I am skeptical that you care what is true.  I think that
your words can be dismissed as relatively valueless on
that basis.

I do not care if you play with the words 'water' and
'liquid'.  It is reasonable to consider your words
to be relatively meaningless because you do not care
what is true to begin with.

 > ...

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#667993

On 1/1/26 08:19, Stefan Ram wrote:
 > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
 > :that mass could be converted to energy as
 > :predicted by Einstein's E = mc².
 >
 >    I can spot three mistakes here right off the bat.
 >
 >         First, the phrase "mass could be converted to energy" is based on
 >    a misconception, since mass already /is/ a form of energy - there's no
 >    "conversion" happening. It's like saying, "water can be turned into a
 >    liquid" - no, water /is/ a liquid.

The basic problem is that you think that 'science' is
'automatically true' and all you have to do is say
words that sound like 'science' and they are automatically
'true' because they 'sound like science'.

For your words to have value, you must care what is true.

I am skeptical that you care what is true.  I think that
your words can be dismissed as relatively valueless on
that basis.

I do not care if you play with the words 'water' and
'liquid'.  It is reasonable to consider your words
to be relatively meaningless because you do not care
what is true to begin with.

 > ...

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#667994

x wrote:
> On 1/1/26 08:19, Stefan Ram wrote:
>  > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
>  > :that mass could be converted to energy as
>  > :predicted by Einstein's E = mc².
>  >
>  >    I can spot three mistakes here right off the bat.
>  >
>  >         First, the phrase "mass could be converted to energy" is based on
>  >    a misconception, since mass already /is/ a form of energy - there's no
>  >    "conversion" happening. It's like saying, "water can be turned into a
>  >    liquid" - no, water /is/ a liquid.

Correct.

> The basic problem is that you think that 'science' is
> 'automatically true' [...]

No, the problem is that you have no clue what you are talking about, but you
are too incompetent to realize that:

<https://en.wikipedia.org/wiki/Dunning–Kruger_effect>

Also, you have posted this twice.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#667995

On 1/2/26 12:07, Thomas 'PointedEars' Lahn wrote:
> x wrote:
>> On 1/1/26 08:19, Stefan Ram wrote:
>>   > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
>>   > :that mass could be converted to energy as
>>   > :predicted by Einstein's E = mc².
>>   >
>>   >    I can spot three mistakes here right off the bat.
>>   >
>>   >         First, the phrase "mass could be converted to energy" is based on
>>   >    a misconception, since mass already /is/ a form of energy - there's no
>>   >    "conversion" happening. It's like saying, "water can be turned into a
>>   >    liquid" - no, water /is/ a liquid.
> 
> Correct.
> 
>> The basic problem is that you think that 'science' is
>> 'automatically true' [...]
> 
> No, the problem is that you have no clue what you are talking about, but you
> are too incompetent to realize that:

You are afraid of not being omniscient.  I will make a note of that.
> 
> <https://en.wikipedia.org/wiki/Dunning–Kruger_effect>
> 
> Also, you have posted this twice.

Yes, I did so by mistake.  I am capable of doing that.

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#667996

On 1/2/26 12:07, Thomas 'PointedEars' Lahn wrote:
> x wrote:
>> On 1/1/26 08:19, Stefan Ram wrote:
>>   > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
>>   > :that mass could be converted to energy as
>>   > :predicted by Einstein's E = mc².
>>   >
>>   >    I can spot three mistakes here right off the bat.
>>   >
>>   >         First, the phrase "mass could be converted to energy" is based on
>>   >    a misconception, since mass already /is/ a form of energy - there's no
>>   >    "conversion" happening. It's like saying, "water can be turned into a
>>   >    liquid" - no, water /is/ a liquid.
> 
> Correct.
> 
>> The basic problem is that you think that 'science' is
>> 'automatically true' [...]
> 
> No, the problem is that you have no clue what you are talking about, but you
> are too incompetent to realize that:

You appear to be afraid of being omniscient, however I
do not know if I will make any note of it on usenet.

I do not care if you are omniscient or not.  I am
thinking that if you are an omniscient being, but
are either lying or never explain yourself, then
your omniscience is useless to me?  I am not sure.
> 
> <https://en.wikipedia.org/wiki/Dunning–Kruger_effect>
> 
> Also, you have posted this twice.

I was aware that I posted this twice earlier, and I do not
know if there is something wrong with some part of usenet
that makes it unable to post unless you post twice.  Should
I care?  Maybe or maybe not.

> 

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#668001

x wrote:
> On 1/2/26 12:07, Thomas 'PointedEars' Lahn wrote:
>> x wrote:
>>> The basic problem is that you think that 'science' is
>>> 'automatically true' [...]
>>
>> No, the problem is that you have no clue what you are talking
>> about, but you are too incompetent to realize that:
> 
> You appear to be afraid of being omniscient,
> [...]
>
>> Also, you have posted this twice.
> 
> I was aware that I posted this twice earlier, and I do not
> know if there is something wrong with some part of usenet
> that makes it unable to post unless you post twice.  Should
> I care?  Maybe or maybe not.

You are insane.  Get well soon.

F'up2 poster

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#668019

Am Freitag000002, 02.01.2026 um 21:07 schrieb Thomas 'PointedEars' Lahn:
> x wrote:
>> On 1/1/26 08:19, Stefan Ram wrote:
>>   > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
>>   > :that mass could be converted to energy as
>>   > :predicted by Einstein's E = mc².
>>   >
>>   >    I can spot three mistakes here right off the bat.
>>   >
>>   >         First, the phrase "mass could be converted to energy" is based on
>>   >    a misconception, since mass already /is/ a form of energy - there's no
>>   >    "conversion" happening. It's like saying, "water can be turned into a
>>   >    liquid" - no, water /is/ a liquid.
> 
> Correct.
NO!!!

Water is not a liquid per se.

Instead water occurs in three different states, from which only one is 
liquid.


Energy is also something else than mass, because the term 'energy' 
denotes a quantity in physics and this has a different meaning than 'mass'.

Mass is actually a measure for resistance against acceleration and 
measured in kg.

Energy is derived from the quantity work, which is defined as 
W=force*distance.

The units are Newtonmeter or Joule.

The quantity you erroneously call 'mass' is not measured in kg but in mol.

What you actually wanted to say, that is: matter is actually immaterial 
and a form of energy.

BUT: 'the amount of matter' is not measured in kg but in mol.

...

TH

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#668023

Thomas Heger <ttt_heg@web.de> wrote:

> Am Freitag000002, 02.01.2026 um 21:07 schrieb Thomas 'PointedEars' Lahn:
> > x wrote:
> >> On 1/1/26 08:19, Stefan Ram wrote:
> >>   > "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
> >>   > :that mass could be converted to energy as
> >>   > :predicted by Einstein's E = mc?.
> >>   >
> >>   >    I can spot three mistakes here right off the bat.
> >>   >
> >>   >         First, the phrase "mass could be converted to energy" is
> >>   >    based on a misconception, since mass already /is/ a form of
> >>   >    energy - there's no "conversion" happening. It's like saying,
> >>   >    "water can be turned into a liquid" - no, water /is/ a liquid.
> > 
> > Correct.
> NO!!!
> 
> Water is not a liquid per se.
> 
> Instead water occurs in three different states, from which only one is
> liquid.
> 
> 
> Energy is also something else than mass, because the term 'energy' 
> denotes a quantity in physics and this has a different meaning than 'mass'.
> 
> Mass is actually a measure for resistance against acceleration and 
> measured in kg.
> 
> Energy is derived from the quantity work, which is defined as 
> W=force*distance.
> 
> The units are Newtonmeter or Joule.
> 
> The quantity you erroneously call 'mass' is not measured in kg but in mol.
> 
> What you actually wanted to say, that is: matter is actually immaterial
> and a form of energy.
> 
> BUT: 'the amount of matter' is not measured in kg but in mol.

You are way behind the times.
As of the CGPM 2018 both the kilogram and the joule are defined 
as numerical multiples of the Hz. (with defined constants in between)
So the relation between them is a numerical constant too,

Jan

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#668065

Am Sonntag000004, 04.01.2026 um 12:28 schrieb J. J. Lodder:
...

>> Energy is also something else than mass, because the term 'energy'
>> denotes a quantity in physics and this has a different meaning than 'mass'.
>>
>> Mass is actually a measure for resistance against acceleration and
>> measured in kg.
>>
>> Energy is derived from the quantity work, which is defined as
>> W=force*distance.
>>
>> The units are Newtonmeter or Joule.
>>
>> The quantity you erroneously call 'mass' is not measured in kg but in mol.
>>
>> What you actually wanted to say, that is: matter is actually immaterial
>> and a form of energy.
>>
>> BUT: 'the amount of matter' is not measured in kg but in mol.
> 
> You are way behind the times.
> As of the CGPM 2018 both the kilogram and the joule are defined
> as numerical multiples of the Hz. (with defined constants in between)
> So the relation between them is a numerical constant too,

Well, actually I can read and I found this on the CGPM website:

"In the 14th CGPM, the SI was completed by adding mole as a base unit 
for amount of substance, making the total number of base units seven."

> 
TH

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#668072

Thomas Heger <ttt_heg@web.de> wrote:

> Am Sonntag000004, 04.01.2026 um 12:28 schrieb J. J. Lodder:
> ...
> 
> >> Energy is also something else than mass, because the term 'energy'
> >> denotes a quantity in physics and this has a different meaning than 'mass'.
> >>
> >> Mass is actually a measure for resistance against acceleration and
> >> measured in kg.
> >>
> >> Energy is derived from the quantity work, which is defined as
> >> W=force*distance.
> >>
> >> The units are Newtonmeter or Joule.
> >>
> >> The quantity you erroneously call 'mass' is not measured in kg but in mol.
> >>
> >> What you actually wanted to say, that is: matter is actually immaterial
> >> and a form of energy.
> >>
> >> BUT: 'the amount of matter' is not measured in kg but in mol.
> > 
> > You are way behind the times.
> > As of the CGPM 2018 both the kilogram and the joule are defined
> > as numerical multiples of the Hz. (with defined constants in between)
> > So the relation between them is a numerical constant too,
> 
> Well, actually I can read and I found this on the CGPM website:
> 
> "In the 14th CGPM, the SI was completed by adding mole as a base unit
> for amount of substance, making the total number of base units seven."

You really are way behind the times, that was more than 50 years ago.

The mole is just another defined number, these days,
(and it does not have any fundamental significance)

Jan

-- 
"One mole is an aggregate of exactly 6.02214076?1023 elementary
entities" (SI as it is nowadays)
('entities' may be electrons, atoms, molecules, whatever)

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#668075

On 01/06/2026 01:56 AM, J. J. Lodder wrote:
> Thomas Heger <ttt_heg@web.de> wrote:
>
>> Am Sonntag000004, 04.01.2026 um 12:28 schrieb J. J. Lodder:
>> ...
>>
>>>> Energy is also something else than mass, because the term 'energy'
>>>> denotes a quantity in physics and this has a different meaning than 'mass'.
>>>>
>>>> Mass is actually a measure for resistance against acceleration and
>>>> measured in kg.
>>>>
>>>> Energy is derived from the quantity work, which is defined as
>>>> W=force*distance.
>>>>
>>>> The units are Newtonmeter or Joule.
>>>>
>>>> The quantity you erroneously call 'mass' is not measured in kg but in mol.
>>>>
>>>> What you actually wanted to say, that is: matter is actually immaterial
>>>> and a form of energy.
>>>>
>>>> BUT: 'the amount of matter' is not measured in kg but in mol.
>>>
>>> You are way behind the times.
>>> As of the CGPM 2018 both the kilogram and the joule are defined
>>> as numerical multiples of the Hz. (with defined constants in between)
>>> So the relation between them is a numerical constant too,
>>
>> Well, actually I can read and I found this on the CGPM website:
>>
>> "In the 14th CGPM, the SI was completed by adding mole as a base unit
>> for amount of substance, making the total number of base units seven."
>
> You really are way behind the times, that was more than 50 years ago.
>
> The mole is just another defined number, these days,
> (and it does not have any fundamental significance)
>
> Jan
>


What, you never heard of "running constants"?

People keep forgetting what makes the old they've
wrapped as new then wondering why it won't sit straight.

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#668076

Ross Finlayson <ross.a.finlayson@gmail.com> wrote:

> On 01/06/2026 01:56 AM, J. J. Lodder wrote:
> > Thomas Heger <ttt_heg@web.de> wrote:
> >
> >> Am Sonntag000004, 04.01.2026 um 12:28 schrieb J. J. Lodder:
> >> ...
> >>
> >>>> Energy is also something else than mass, because the term 'energy'
> >>>> denotes a quantity in physics and this has a different meaning than
> >>>> 'mass'.
> >>>>
> >>>> Mass is actually a measure for resistance against acceleration and
> >>>> measured in kg.
> >>>>
> >>>> Energy is derived from the quantity work, which is defined as
> >>>> W=force*distance.
> >>>>
> >>>> The units are Newtonmeter or Joule.
> >>>>
> >>>> The quantity you erroneously call 'mass' is not measured in kg but in
> >>>>mol.
> >>>>
> >>>> What you actually wanted to say, that is: matter is actually
> >>>> immaterial and a form of energy.
> >>>>
> >>>> BUT: 'the amount of matter' is not measured in kg but in mol.
> >>>
> >>> You are way behind the times.
> >>> As of the CGPM 2018 both the kilogram and the joule are defined
> >>> as numerical multiples of the Hz. (with defined constants in between)
> >>> So the relation between them is a numerical constant too,
> >>
> >> Well, actually I can read and I found this on the CGPM website:
> >>
> >> "In the 14th CGPM, the SI was completed by adding mole as a base unit
> >> for amount of substance, making the total number of base units seven."
> >
> > You really are way behind the times, that was more than 50 years ago.
> >
> > The mole is just another defined number, these days,
> > (and it does not have any fundamental significance)
> >
> > Jan
> >
> 
> 
> What, you never heard of "running constants"?
> 
> People keep forgetting what makes the old they've
> wrapped as new then wondering why it won't sit straight.

What part of  '(exactly)'  don't you understand?

Jan

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#668033

Den 01.01.2026 17:19, skrev Stefan Ram:
> "Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
> :that mass could be converted to energy as
> :predicted by Einstein's E = mc².

I resent very much that you:
1. Break threads so it is impossible to see to what you are responding.
2. Paraphrase and not quote.

I can guess that you were responding to my statement:
  "The atom bomb proved in a very convincing way
   that mass could be converted to energy as
   predicted by Einstein's E = mc²."

This statement isn't very precise, but not wrong.
So let's look at a more precise statement about
what is happening in an atomic fission bomb:

One possible fission process is:

1n + U-235 → Ba-141 + Kr-92 + 3n

The atomic weight (mass) of these are:

Left side:
1n      1.008664  u
U-235 235.0439299 u
-------------------
       236.0525939 u = 3.919748214E-25 kg

Right side:
Ba-141   140.914412 u
Kr-92     91.926156 u
3n         3.025992 u
---------------------
          235.866560 u = 3.916659047E-25 kg

Lost mass: m = 0.1860339 u = 3.089167695E-28 kg

E = mc² ≈ 2.776404839E-11 J

> 
>    I can spot three mistakes here right off the bat.
> 
>         First, the phrase "mass could be converted to energy" is based on
>    a misconception, since mass already /is/ a form of energy - there's no
>    "conversion" happening. It's like saying, "water can be turned into a
>    liquid" - no, water /is/ a liquid.

Note that m = 3.089167695E-28 kg is the _lost_ mass,
it doesn't exist any more.
So where has it gone?
It is converted to E = mc² ≈ 2.776404839E-11 J of _kinetic energy_.
Kinetic energy is not mass. Thus "convert".

> 
>         Second, "E=mc^2" only applies to systems at rest. In general,
>    it's "E^2=(mc^2)^2+(pc)^2", where "p" is the system's momentum.
>    (That basically says mass is the magnitude of the four-momentum.)

E = mc² is the energy content, or the energy equivalent of
the mass m. Mass is invariant, so this equation is valid for
all speeds of the mass.

However, the _total_ energy of a moving mass is:
E = mγc² = mc² + (γ-1)mc²
The first term mc² is the invariant energy content of the mass m,
the second term is the kinetic energy of the mass m.
Kinetic energy is not mass!

> 
>         Third, mass is conserved in nuclear fission. This point is often
>    explained incorrectly, even in otherwise solid textbooks like Grif-
>    fiths.

Could it be that you are wrong and the textbook is right? :-D

Before the fission the mass of the U-235 nucleus + 1 neutron
is: m₁ = 3.919748214E-25 kg

After the fission the mass of the Ba-141 and Kr-92 nuclei + 3 neutrons
is: m₂ = 3.916659047E-25 kg.

So the mass isn't conserved, m = m₁-m₂= 3.089167695E-28 kg has
disappeared because it is converted to kinetic energy which is not mass.

The energy is conserved, though.

Energy before fission:
Energy content of mass m₁ = m₁c² = 3.522894007E-8 J
Total energy before fission E₁ = 3.522894007E-8 J

Energy after fission:
Energy content of mass m₂     E  = m₂c²      = 3.520117602E-8 J
Kinetic energy from lost mass K  = (m₁-m₂)c² = 2.776404839E-11 J
Total energy after fission    E₂ = E + K     = 3.522894007E-8

E₁ = E₂ energy conserved


-- 
Paul

https://paulba.no/

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#668063

Paul.B.Andersen wrote:
> Note that m = 3.089167695E-28 kg is the _lost_ mass,
> it doesn't exist any more.
> So where has it gone?
> It is converted to E = mc² ≈ 2.776404839E-11 J of _kinetic energy_.
> Kinetic energy is not mass. Thus "convert".

/Non sequitur./

>>         Second, "E=mc^2" only applies to systems at rest. In general,
>>    it's "E^2=(mc^2)^2+(pc)^2", where "p" is the system's momentum.
>>    (That basically says mass is the magnitude of the four-momentum.)
> 
> E = mc² is the energy content, or the energy equivalent of
> the mass m.

The first wording is simply wrong.  E (better: E₀) is the *rest* energy of
_an object_ whose mass is m.  One can also call that the energy content _of
that object_ at relative rest (as Einstein did, but this wording is
obsolete), but NOT "of the mass".  Mass is a quantity, not a object; a
quantity has no content.

> Mass is invariant, so this equation is valid for all speeds of the mass.

Again, mass is a quantity, NOT an object.  It does not make sense to say
"speeds of the mass".  That makes as much sense as e.g. "mass of the charge".

> However, the _total_ energy of a moving mass is:
> E = mγc² = mc² + (γ-1)mc²
> The first term mc² is the invariant energy content of the mass m,

No, the first term is the rest energy equivalent to the mass m.

Mass does not have an energy content, _objects_ have.

> the second term is the kinetic energy of the mass m.

No, it is the kinetic energy of an _object_ with mass m and relative speed
v, hidden in γ = γ(v).

> Kinetic energy is not mass!

And mass is NOT energy or "has energy".  You would be well to realize that.

>>         Third, mass is conserved in nuclear fission. This point is often
>>    explained incorrectly, even in otherwise solid textbooks like Grif-
>>    fiths.
> 
> Could it be that you are wrong and the textbook is right? :-D

He is wrong, obviously.  But you are also wrong in multiple respects:

> Before the fission the mass of the U-235 nucleus + 1 neutron
> is: m₁ = 3.919748214E-25 kg
> 
> After the fission the mass of the Ba-141 and Kr-92 nuclei + 3 neutrons
> is: m₂ = 3.916659047E-25 kg.
> 
> So the mass isn't conserved,

Correct.

> m = m₁-m₂= 3.089167695E-28 kg has disappeared because it is converted to
> kinetic energy which is not mass.

Again: NOT the mass is partially converted to kinetic energy, but the rest
energy E_0 = m c^2 *equivalent to* the mass m.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#668085

Den 06.01.2026 03:04, skrev Thomas 'PointedEars' Lahn:
>> E = mc² is the energy content, or the energy equivalent of
>> the mass m.
> 
> The first wording is simply wrong.  E (better: E₀) is the *rest* energy of
> _an object_ whose mass is m.  One can also call that the energy content _of
> that object_ at relative rest (as Einstein did, but this wording is
> obsolete), but NOT "of the mass".  Mass is a quantity, not a object; a
> quantity has no content.

You are nit-picking again!
Of course "mass" is the mass of an object.
and E = mc² is the energy content of the mass of an object.

It is quite common to write things like:
   "Let the speed of the mass m be v".
Everybody will understand that m is the mass of an object.
And so do you. So why the nit-picking ?
This is a post in a Usenet group, not a scientific paper.

Back to the subject:

The mass of an objects is invariant, and so is the energy
content of the object.
The E in the equation E = mc² is invariant, which means
that it is independent of the speed of the object.

It makes no sense to call E = mc² "the *rest* energy of
_an object_ whose mass is m."

The energy of a moving object with mass m is:
   E = γmc² = mc² + (γ-1)mc²
The term mc² is the invariant energy content of the object with mass m,
the term (γ-1)mc² is the kinetic energy of the object with mass m.

The energy content E = mc² of the object with mass m
is a property of the object with mass m.

But a frame dependent entity like kinetic energy or relative speed
is not a property of the moving object.
They are properties of the relationship between the object
and a frame of reference.

The kinetic energy which can have any value depending on
the arbitrary choice of frame of reference, is not part
of the energy content of the object.

(Note however that in the fission where the two
nuclei and 3 neutrons are moving away from each other
in such a way that momentum is conserved, the _sum_
of their kinetic energies is invariant.)

-------

>> m = m₁-m₂= 3.089167695E-28 kg has disappeared because it is converted to
>> kinetic energy which is not mass.
Quote out of context:

Before the fission the mass of the U-235 nucleus + 1 neutron
is: m₁ = 3.919748214E-25 kg

After the fission the mass of the Ba-141 and Kr-92 nuclei +
3 neutrons is: m₂ = 3.916659047E-25 kg.

So the mass isn't conserved, Δm = m₁-m₂= 3.089167695E-28 kg

> 
> Again: NOT the mass is partially converted to kinetic energy, but the rest
> energy E_0 = m c^2 *equivalent to* the mass m.

Energy before fission:
Energy content of mass m₁: E = m₁c² = 3.522894007E-8 J

Energy after fission:
Energy content of mass m₂: E  = m₁c²= 3.520117602E-8 J

The difference is ΔE = m₁c² - m₁c² = Δm⋅c² = 3.089167695E-28 J

The binding energy holding the nucleons together is
part of the energy content of the mass of the U-235 nucleus.
When the nucleus is split, the binding energy in the Ba-141
and Kr-92 nuclei will be ΔE less. The sum of the kinetic energy
of the two nuclei and 3 neutrons will be ΔE = 3.089167695E-28 J

I say that the mass Δm lost from the U-235 nucleus is converted
to kinetic energy  of the two nuclei and 3 neutrons.

You are free to choose your wording.

-- 
Paul

https://paulba.no/

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#668086

Den 06.01.2026 22:12, skrev Paul.B.Andersen:
> Energy before fission:
> Energy content of mass m₁: E = m₁c² = 3.522894007E-8 J
> 
> Energy after fission:
> Energy content of mass m₂: E  = m₁c²= 3.520117602E-8 J
> 
> The difference is ΔE = m₁c² - m₁c² = Δm⋅c² = 3.089167695E-28 J

Typo.  ΔE = 2.776404839E-11 J


-- 
Paul

https://paulba.no/

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#668087

On 01/06/2026 01:12 PM, Paul.B.Andersen wrote:
> Den 06.01.2026 03:04, skrev Thomas 'PointedEars' Lahn:
>>> E = mc² is the energy content, or the energy equivalent of
>>> the mass m.
>>
>> The first wording is simply wrong.  E (better: E₀) is the *rest*
>> energy of
>> _an object_ whose mass is m.  One can also call that the energy
>> content _of
>> that object_ at relative rest (as Einstein did, but this wording is
>> obsolete), but NOT "of the mass".  Mass is a quantity, not a object; a
>> quantity has no content.
>
> You are nit-picking again!
> Of course "mass" is the mass of an object.
> and E = mc² is the energy content of the mass of an object.
>
> It is quite common to write things like:
>    "Let the speed of the mass m be v".
> Everybody will understand that m is the mass of an object.
> And so do you. So why the nit-picking ?
> This is a post in a Usenet group, not a scientific paper.
>
> Back to the subject:
>
> The mass of an objects is invariant, and so is the energy
> content of the object.
> The E in the equation E = mc² is invariant, which means
> that it is independent of the speed of the object.
>
> It makes no sense to call E = mc² "the *rest* energy of
> _an object_ whose mass is m."
>
> The energy of a moving object with mass m is:
>    E = γmc² = mc² + (γ-1)mc²
> The term mc² is the invariant energy content of the object with mass m,
> the term (γ-1)mc² is the kinetic energy of the object with mass m.
>
> The energy content E = mc² of the object with mass m
> is a property of the object with mass m.
>
> But a frame dependent entity like kinetic energy or relative speed
> is not a property of the moving object.
> They are properties of the relationship between the object
> and a frame of reference.
>
> The kinetic energy which can have any value depending on
> the arbitrary choice of frame of reference, is not part
> of the energy content of the object.
>
> (Note however that in the fission where the two
> nuclei and 3 neutrons are moving away from each other
> in such a way that momentum is conserved, the _sum_
> of their kinetic energies is invariant.)
>
> -------
>
>>> m = m₁-m₂= 3.089167695E-28 kg has disappeared because it is converted to
>>> kinetic energy which is not mass.
> Quote out of context:
>
> Before the fission the mass of the U-235 nucleus + 1 neutron
> is: m₁ = 3.919748214E-25 kg
>
> After the fission the mass of the Ba-141 and Kr-92 nuclei +
> 3 neutrons is: m₂ = 3.916659047E-25 kg.
>
> So the mass isn't conserved, Δm = m₁-m₂= 3.089167695E-28 kg
>
>>
>> Again: NOT the mass is partially converted to kinetic energy, but the
>> rest
>> energy E_0 = m c^2 *equivalent to* the mass m.
>
> Energy before fission:
> Energy content of mass m₁: E = m₁c² = 3.522894007E-8 J
>
> Energy after fission:
> Energy content of mass m₂: E  = m₁c²= 3.520117602E-8 J
>
> The difference is ΔE = m₁c² - m₁c² = Δm⋅c² = 3.089167695E-28 J
>
> The binding energy holding the nucleons together is
> part of the energy content of the mass of the U-235 nucleus.
> When the nucleus is split, the binding energy in the Ba-141
> and Kr-92 nuclei will be ΔE less. The sum of the kinetic energy
> of the two nuclei and 3 neutrons will be ΔE = 3.089167695E-28 J
>
> I say that the mass Δm lost from the U-235 nucleus is converted
> to kinetic energy  of the two nuclei and 3 neutrons.
>
> You are free to choose your wording.
>

In Einstein's original formula,
the E of the mass is of the K.E.,
the kinetic energy, and the mc^2 is
only the first term of the Taylor series
expansion, all the rest not only having
different units in the dimensional analysis
yet being higher-order terms usually considered
negligeable, yet, as a numerical method an
approximation, of course there's a non-zero error term,
which would be considered the content and meaning
of the higher-order terms.


K.E. = mc^2 + error_term()


If you think that's fun, consider the notion
that any actual change in velocity at all
has nominally infinitely-many nominally non-zero
higher-order terms of acceleration -
almost all of them infinitesimal.


Things like this like Hooke's law and
Clausius/Arrhenius are very common in
physics, Einstein's mass/energy equivalency
formula, a truncation of an expression.

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#668088

Le 06/01/2026 à 22:43, Ross Finlayson a écrit :
> [snip non sense] Einstein's mass/energy equivalency
> formula, a truncation of an expression.

You are the result of the truncation of sanity, Ross.

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