Mass-Energy Equivalence [Physics]

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From: Tony M on 6 Apr 2010 08:58

On Apr 5, 2:40 pm, PD <thedraperfam...(a)gmail.com> wrote:
> On Apr 5, 1:35 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote:
>
>
>
>
>
> > On Apr 5, 2:18 pm, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Apr 4, 12:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote:
>
> > > > On Apr 3, 10:23 pm, Tom Roberts wrote:
>
> > > > > Tony M wrote:
> > > > > > As per the mass-energy equivalence, can I assume the following is
> > > > > > valid?
>
> > > > > In relativity, which I assume is the context for your question, mass and energy
> > > > > are not "equivalent" in the manner you seem to think. They are in certain
> > > > > circumstances inter-convertible, but are most definitely not the same.
>
> > > > This is unbelievable. Self-styled physicists came up with (E = m
> > > > c^2). Now, they are walking away from it and speak with a forked
> > > > tongue. These clowns are very liberally interpreting the scripture
> > > > according to their religion. That's what you get for liberal-art
> > > > schools, I guess. <shrug>
>
> > > E=mc^2 in no way implies that mass and energy are equivalent, any more
> > > than F=ma implies that force and acceleration are equivalent.
>
> > > The equation relates the quantitative values of two distinct physical
> > > variables. That's what equations do.
>
> > > If you cannot read an equation, then perhaps you should read some
> > > sentences that precede and follow the equation where it is presented.
>
> > <<...an electron and a positron, each with a mass
> > of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy.>>http://en.wikipedia.org/wiki/Electronvolt
>
> > Sue...
>
> Yes, indeed. There is the numerical equality I was talking about. Note
> that a processes where the collision of two objects with mass produces
> a predictable amount of energy does not imply that mass and energy are
> equivalent. Perhaps you have the same difficulty that KW is having.- Hide quoted text -
>
> - Show quoted text -

I think you're right PD, mass and energy are not the same thing. Maybe
"equivalence" is not the best word, "duality" is probably better. The
way I see it, mass and energy are two sides of the same coin, one
cannot convert mass to energy and vice-versa. For a certain amount of
energy in a system there will always be a corresponding amount of
mass, as per E=mc2.

Sue's example of electron-positron "annihilation" can be a bit
misleading, making one believe that mass gets converted to energy,
when that's not the case. The isolated system consisting of the
electron and positron has the same total energy and corresponding mass
before and after the "annihilation", except now instead of electron
and positron we have gamma photons (and maybe some other particles).

From: Sue... on 6 Apr 2010 09:14

On Apr 6, 8:58 am, Tony M <marc...(a)gmail.com> wrote:
> On Apr 5, 2:40 pm, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Apr 5, 1:35 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote:
>
> > > On Apr 5, 2:18 pm, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > On Apr 4, 12:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote:
>
> > > > > On Apr 3, 10:23 pm, Tom Roberts wrote:
>
> > > > > > Tony M wrote:
> > > > > > > As per the mass-energy equivalence, can I assume the following is
> > > > > > > valid?
>
> > > > > > In relativity, which I assume is the context for your question, mass and energy
> > > > > > are not "equivalent" in the manner you seem to think. They are in certain
> > > > > > circumstances inter-convertible, but are most definitely not the same.
>
> > > > > This is unbelievable. Self-styled physicists came up with (E = m
> > > > > c^2). Now, they are walking away from it and speak with a forked
> > > > > tongue. These clowns are very liberally interpreting the scripture
> > > > > according to their religion. That's what you get for liberal-art
> > > > > schools, I guess. <shrug>
>
> > > > E=mc^2 in no way implies that mass and energy are equivalent, any more
> > > > than F=ma implies that force and acceleration are equivalent.
>
> > > > The equation relates the quantitative values of two distinct physical
> > > > variables. That's what equations do.
>
> > > > If you cannot read an equation, then perhaps you should read some
> > > > sentences that precede and follow the equation where it is presented.
>
> > > <<...an electron and a positron, each with a mass
> > > of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy.>>http://en.wikipedia.org/wiki/Electronvolt
>
> > > Sue...
>
> > Yes, indeed. There is the numerical equality I was talking about. Note
> > that a processes where the collision of two objects with mass produces
> > a predictable amount of energy does not imply that mass and energy are
> > equivalent. Perhaps you have the same difficulty that KW is having.- Hide quoted text -
>
> > - Show quoted text -
>
> I think you're right PD, mass and energy are not the same thing. Maybe
> "equivalence" is not the best word, "duality" is probably better. The
> way I see it, mass and energy are two sides of the same coin, one
> cannot convert mass to energy and vice-versa. For a certain amount of
> energy in a system there will always be a corresponding amount of
> mass, as per E=mc2.
>
> Sue's example of electron-positron "annihilation" can be a bit
> misleading, making one believe that mass gets converted to energy,
> when that's not the case. The isolated system consisting of the
> electron and positron has the same total energy and corresponding mass
> before and after the "annihilation", except now instead of electron
> and positron we have gamma photons (and maybe some other particles).

You don't have photons 'till there is a causally
related absorption somewhere else and AFAIK no more
fundamental particles are known of.

Not meant to mislead. The story isn't complete
without reversibility and that, thus far seems
to occur only in mathematical models with
pseudo-particles.

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

Perhaps a rare occasion where PD and I
find a bit of agreement so take a picture
and pinch yourself to ensure you are awake.

Sue...

From: mpc755 on 6 Apr 2010 09:25

On Apr 6, 9:14 am, "Sue..." <suzysewns...(a)yahoo.com.au> wrote:
> On Apr 6, 8:58 am, Tony M <marc...(a)gmail.com> wrote:
>
>
>
> > On Apr 5, 2:40 pm, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Apr 5, 1:35 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote:
>
> > > > On Apr 5, 2:18 pm, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > On Apr 4, 12:53 am, Koobee Wublee <koobee.wub...(a)gmail.com> wrote:
>
> > > > > > On Apr 3, 10:23 pm, Tom Roberts wrote:
>
> > > > > > > Tony M wrote:
> > > > > > > > As per the mass-energy equivalence, can I assume the following is
> > > > > > > > valid?
>
> > > > > > > In relativity, which I assume is the context for your question, mass and energy
> > > > > > > are not "equivalent" in the manner you seem to think. They are in certain
> > > > > > > circumstances inter-convertible, but are most definitely not the same.
>
> > > > > > This is unbelievable. Self-styled physicists came up with (E = m
> > > > > > c^2). Now, they are walking away from it and speak with a forked
> > > > > > tongue. These clowns are very liberally interpreting the scripture
> > > > > > according to their religion. That's what you get for liberal-art
> > > > > > schools, I guess. <shrug>
>
> > > > > E=mc^2 in no way implies that mass and energy are equivalent, any more
> > > > > than F=ma implies that force and acceleration are equivalent.
>
> > > > > The equation relates the quantitative values of two distinct physical
> > > > > variables. That's what equations do.
>
> > > > > If you cannot read an equation, then perhaps you should read some
> > > > > sentences that precede and follow the equation where it is presented.
>
> > > > <<...an electron and a positron, each with a mass
> > > > of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy.>>http://en.wikipedia.org/wiki/Electronvolt
>
> > > > Sue...
>
> > > Yes, indeed. There is the numerical equality I was talking about. Note
> > > that a processes where the collision of two objects with mass produces
> > > a predictable amount of energy does not imply that mass and energy are
> > > equivalent. Perhaps you have the same difficulty that KW is having.- Hide quoted text -
>
> > > - Show quoted text -
>
> > I think you're right PD, mass and energy are not the same thing. Maybe
> > "equivalence" is not the best word, "duality" is probably better. The
> > way I see it, mass and energy are two sides of the same coin, one
> > cannot convert mass to energy and vice-versa. For a certain amount of
> > energy in a system there will always be a corresponding amount of
> > mass, as per E=mc2.
>
> > Sue's example of electron-positron "annihilation" can be a bit
> > misleading, making one believe that mass gets converted to energy,
> > when that's not the case. The isolated system consisting of the
> > electron and positron has the same total energy and corresponding mass
> > before and after the "annihilation", except now instead of electron
> > and positron we have gamma photons (and maybe some other particles).
>
> You don't have photons 'till there is a causally
> related absorption somewhere else and AFAIK no more
> fundamental particles are known of.
>
> Not meant to mislead. The story isn't complete
> without reversibility and that, thus far seems
> to occur only in mathematical models with
> pseudo-particles.
>
> http://en.wikipedia.org/wiki/Dirac_sea
>
> Perhaps a rare occasion where PD and I
> find a bit of agreement so take a picture
> and pinch yourself to ensure you are awake.
>
> Sue...

http://aether.lbl.gov/image_all.html

The 1st Stars form where the pressure is great enough to compress the
aether into matter.

From: mpc755 on 6 Apr 2010 09:35

From: Tom Roberts on 6 Apr 2010 10:29

Tony M wrote:
> Sue's example of electron-positron "annihilation" can be a bit
> misleading, making one believe that mass gets converted to energy,
> when that's not the case.

Again this depends on the meanings of your words, including nuances. With
standard meanings we do say "mass is converted into kinetic energy". See below.

> The isolated system consisting of the
> electron and positron has the same total energy and corresponding mass
> before and after the "annihilation", except now instead of electron
> and positron we have gamma photons (and maybe some other particles).

e+ e- annihilate from rest into 2 gammas >99% of the time; the
other final states consist of 4,6,8,... gammas, or (very rarely)
neutrino anti-neutrino pairs. For simplicity, I'll only discuss
annihilation at rest into gammas.

Normally we apply the word "mass" to OBJECTS, not to collections of unbound
objects. In the initial state the electron and the positron EACH have a mass,
and the total mass is 1.022 MeV/c^2. In the final state the gammas each have
zero mass, and the total mass is 0. The total energies of the initial and final
states are the same. The total kinetic energy of the initial state is 0, but the
total kinetic energy of the final state is 1.022 MeV. These units have c=1, and
it is obvious that mass was indeed converted to kinetic energy.

This is relativity; the kinetic energy of an object is its
total energy minus its mass (c=1).

Tom Roberts

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