On Friday, 3 February 2023 at 20:50:30 UTC+1, Tom Roberts wrote:
> On 2/2/23 1:10 PM, RichD wrote:
> > Scale up to a large hemisphere, gathering light from half the sun.
> > Focus it through mirrors and lenses to a small container of
> > hydrogen-helium gas. Its temperature can be raised arbitrarily
> > high.
> Making stuff up and pretending it is true is not a viable approach to
> physics.

But it is exactly the approach of you and your
fellow idiots.

On January 31, Tom Roberts wrote:
>> A magnifying glass focuses sunlight onto a small spot. The spots
>> heats. Thus the machine converts high entropy, low temperature
>> energy, into a higher temperature, low entropy state.
>
> A magnifying glass focuses sunlight into a small spot. But it does NOT
> change the entropy of the light -- for a light beam, such as the
> sunlight that traverses a lens, entropy is proportional to its
> emittance, and there is a theorem that no linear element, such as a
> lens, can change the emittance of a beam. The lens does change a
> large-area, low-divergence beam into a small-area high-divergence beam
> at its focus [#], but does NOT change its emittance.

One would expect that, in an expanding EM wave, the entropy
would naturally increase; think of an expanding gas. So this
is a surprising result.

I suspect it's somehow related to information conservation.
Statistical mechanics is often modeled using an informational
approach.

Assuming the Maxwell equations govern the wave, it's
deterministic in both time directions. Given the state at any
instant, the entire history is fixed. Hence information is
conserved. If entropy is conserved, there must be some
deeper connection.

--
Rich

On February 3, J. J. Lodder wrote:
>>>> A magnifying glass focuses sunlight onto a small spot. The spots
>>>> heats. Thus the machine converts high entropy, low temperature
>>>> energy, into a higher temperature, low entropy state.
>
>> > If you want to talk about heat, you need to use atoms, not light, so
>> > you need start with the sun, which is not "low entropy" at all, and is
>> > very much larger than your lens and its focus. Moreover, do you
>> > seriously think that the hot spot from the lens is "higher temperature"
>> > than the surface of the sun????
>
>> Scale up to a large hemisphere, gathering light from half
>> the sun. Focus it through mirrors and lenses to a small
>> container of hydrogen-helium gas. Its temperature can be
>> raised arbitrarily high.
>
> Another fundamental error. You need to learn about Kirchhoff's Laws
> <https://en.wikipedia.org/wiki/Kirchhoff%27s_law_of_thermal_radiation>
>
> In the simplest form:
> ===
> For an arbitrary body emitting and absorbing thermal radiation in
> thermodynamic equilibrium, the emissivity is equal to the absorptivity.
> ===
> So applied to your magnifying glass: the focus cannot become hotter
> than the surface of the sun.

As stated, it says that the target absorbs and emits at its surface
at an equal rate, if in equilibrium. That is, equilibrium with its
immediate environment. It doesn't say that the target's temperature
must be the same as the energy source, far away.

In this case, the hypothetical lens is gigantic, capturing a large
fraction of the sun's output.

> Kirchhoff derived his laws from the consideration
> that the mistake that you made cannot reflect physical reality.

--
Rich

RichD <r_delaney2001@yahoo.com> wrote:

> On February 3, J. J. Lodder wrote:
> >>>> A magnifying glass focuses sunlight onto a small spot. The spots
> >>>> heats. Thus the machine converts high entropy, low temperature
> >>>> energy, into a higher temperature, low entropy state.
> >
> >> > If you want to talk about heat, you need to use atoms, not light, so
> >> > you need start with the sun, which is not "low entropy" at all, and is
> >> > very much larger than your lens and its focus. Moreover, do you
> >> > seriously think that the hot spot from the lens is "higher temperature"
> >> > than the surface of the sun????
> >
> >> Scale up to a large hemisphere, gathering light from half
> >> the sun. Focus it through mirrors and lenses to a small
> >> container of hydrogen-helium gas. Its temperature can be
> >> raised arbitrarily high.
> >
> > Another fundamental error. You need to learn about Kirchhoff's Laws
> > <https://en.wikipedia.org/wiki/Kirchhoff%27s_law_of_thermal_radiation>
> >
> > In the simplest form:
> > ===
> > For an arbitrary body emitting and absorbing thermal radiation in
> > thermodynamic equilibrium, the emissivity is equal to the absorptivity.
> > ===
> > So applied to your magnifying glass: the focus cannot become hotter
> > than the surface of the sun.
>
> As stated, it says that the target absorbs and emits at its surface
> at an equal rate, if in equilibrium. That is, equilibrium with its
> immediate environment. It doesn't say that the target's temperature
> must be the same as the energy source, far away.
>
> In this case, the hypothetical lens is gigantic, capturing a large
> fraction of the sun's output.

Do try to understand the physics of it,

Jan

> > Kirchhoff derived his laws from the consideration
> > that the mistake that you made cannot reflect physical reality.
>
> --
> Rich

On Saturday, February 4, 2023 at 7:31:22 PM UTC-6, RichD wrote:

> As stated, it says that the target absorbs and emits at its surface
> at an equal rate, if in equilibrium. That is, equilibrium with its
> immediate environment. It doesn't say that the target's temperature
> must be the same as the energy source, far away.
>
> In this case, the hypothetical lens is gigantic, capturing a large
> fraction of the sun's output.

I told you. Read up about conservation of etendue.
https://en.wikipedia.org/wiki/Etendue

Your idea DOESN'T WORK.

On Friday, February 3, 2023 at 4:50:30 PM UTC-3, Tom Roberts wrote:

<snip>

> Making stuff up and pretending it is true is not a viable approach to
> physics.

<snip>
> Tom Roberts

But, but Einstein............
Then, his longitudinal and traverse masses of the electron are a fail?. Or his length contraction?

On 2/6/2023 4:17 PM, Richard Hertz wrote:
> On Friday, February 3, 2023 at 4:50:30 PM UTC-3, Tom Roberts wrote:
>
> <snip>
>
>> Making stuff up and pretending it is true is not a viable approach to
>> physics.
>
> <snip>
>> Tom Roberts
>
> But, but Einstein............
> Then, his longitudinal and traverse masses of the electron are a fail?. Or his length contraction?

Does it matter since the technology derived from his theories continues
to work well?

On 2/6/2023 5:17 PM, Richard Hertz wrote:
> On Friday, February 3, 2023 at 4:50:30 PM UTC-3, Tom Roberts wrote:
>
> <snip>
>
>> Making stuff up and pretending it is true is not a viable approach to
>> physics.
>
> <snip>
>> Tom Roberts
>
> But, but Einstein............

You mean the very man who continues to slap you silly because you are so
pathetically wrong? Even though he's been dead for many decades?

Richard Hertz <hertz778@gmail.com> wrote:

> On Friday, February 3, 2023 at 4:50:30 PM UTC-3, Tom Roberts wrote:
>
> <snip>
>
> > Making stuff up and pretending it is true is not a viable approach to
> > physics.
>
> <snip>
> > Tom Roberts
>
> But, but Einstein............
> Then, his longitudinal and traverse masses of the electron are a fail?. Or his
> length contraction?

Longitdinal and transverse masses are obsolete.
They are a legacy from people who attempted
to force relativistic mechanics into a Newtonian framework.
They are not needed in a fully relativistic treatment,

Jan

On February 6, prokaryotic.c...@gmail.com wrote:
>> As stated, it says that the target absorbs and emits at its surface
>> at an equal rate, if in equilibrium. That is, equilibrium with its
>> immediate environment. It doesn't say that the target's temperature
>> must be the same as the energy source, far away.
>> In this case, the hypothetical lens is gigantic, capturing a large
>> fraction of the sun's output.
>
> I told you. Read up about conservation of etendue.

Entendu.

> https://en.wikipedia.org/wiki/Etendue
> Your idea DOESN'T WORK.

You're confused.

This etendue thigamajig concerns brightness-area, and its
conservation, related to conservation of energy. It says nothing
about temperature or entropy, the content of the lens paradox.

If you weren't so lazy, you might READ the note to which you
respond, and read your own references.

I'll spell it out. In a spontaneous thermal system, entropy increases.
Intuitively, one expects that as a light wave spreads and thins, its
temperature should decrease, and entropy increase. However, a
convex lens concentrates the energy at its focal point, temperature
INCREASES relative to the aperture; apparently anti-entropic. The
second law is overturned!

The explanation is Thermodynamics 101: that law applies to a CLOSED
SYSTEM. But a lens transports energy through both ends. To close
the system, we need to start at the original patch of sun surface,
through space, through the lens, diverging out the other side. Finally,
capture the light, feed it back to the source, see if it raises the
temperature. Unlikely.

The purpose of all such paradoxes is to test the student. You flunked.

--
Rich

On February 6, Richard Hertz wrote:
>> Making stuff up and pretending it is true is not a viable approach to physics.
>
> But, but Einstein............

Don't forget Pauli and his neutrinos -

--
Rich

On 2/7/23 4:05 PM, RichD wrote:
> This etendue thigamajig concerns brightness-area, and its
> conservation, related to conservation of energy.

The entendu of a light beam is what accelerator physicists call
emittance, considering the light beam as a bundle of light rays. There
are theorems about its conservation, and linear elements, such as
lenses, cannot change it. In particular, the entendu of the image of a
lens is equal to the entendu of the light source, considering only light
from the source that reaches the image.

This is NOT conservation of energy, though it ought to be obvious that
if a light beam is propagated without loss, the energy of the beam is
constant all along its path; ditto for a particle beam. For a light
beam, entendu is proportional to entropy; for a particle beam, emittance
is proportional to entropy.

> It says nothing about temperature or entropy, the content of the lens
> paradox.

It says nothing about temperature, but entendu is directly related to
the entropy of the light beam.

Note also that temperature is a property of an EQUILIBRIUM system. A
light beam is nowhere close to an equilibrium system, and temperature
does not apply to it.

BUT: for the case of a hot light source emitting thermal radiation, and
a lens focusing that into an image and heating an object on which the
image is projected, one can discuss the temperature of the source and
the object -- the latter can never exceed the former.

Hint: if the object was hotter than the source,
the thermal radiation emitted by the object would
propagate in the reverse direction and heat the
source.

> [... lots of misunderstandings and confusions about entropy and
> temperature]

Tom Roberts

On Saturday, 11 February 2023 at 06:57:10 UTC+1, Tom Roberts wrote:
> On 2/7/23 4:05 PM, RichD wrote:
> > This etendue thigamajig concerns brightness-area, and its
> > conservation, related to conservation of energy.
> The entendu of a light beam is what accelerator physicists call

And we're all FORCED!!! To THE BEST WAY!!!!!