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Black body radiation


Black body radiation14-08-2019 17:04
olyz
★☆☆☆☆
(72)
From wiki:

"A closed box of graphite walls at a constant temperature with a small hole on one side produces a good approximation to ideal black-body radiation emanating from the opening.[17][18]"

Presumably this can be verified experimentally. Why doesn't a gap show up in the spectrum at CO2 vibration frequency due to CO2 in the air?
14-08-2019 20:28
IBdaMannProfile picture★★★★★
(4926)
olyz wrote: From wiki:

Dismissed.

olyz wrote: "A closed box of graphite walls at a constant temperature with a small hole on one side produces a good approximation to ideal black-body radiation emanating from the opening.[17][18]"

Question: What's the scientific term for a very close approximation to an ideal black body?

Answer: An ordinary black body.

.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
15-08-2019 02:13
tmiddlesProfile picture★★★★☆
(1327)
olyz wrote:
From wiki:

"A closed box of graphite walls at a constant temperature with a small hole on one side produces a good approximation to ideal black-body radiation emanating from the opening.[17][18]"

Presumably this can be verified experimentally. Why doesn't a gap show up in the spectrum at CO2 vibration frequency due to CO2 in the air?


Olyz you still seem to think that the nature of a body, how much it is or is not a black body, and so on have anything to do with what it radiates.

My understanding is that ANYTHING, jelly donut, granite boulder, planet, will emitt exactly and only what it's temperature corresponds to.

So you wont have Item A and Item B at precisely 500C emitting anything other than the wavelength produced by 500C, even if they are composed of different matter, have different masses, different emissivities, or anything else.
15-08-2019 05:48
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:My understanding is that ANYTHING, jelly donut, granite boulder, planet, will emitt exactly and only what it's temperature corresponds to.

So you wont have Item A and Item B at precisely 500C emitting anything other than the wavelength produced by 500C, even if they are composed of different matter, have different masses, different emissivities, or anything else.

No. I believe you misunderstand.

Only the *power* (Radiance) is determined by the temperature and emissivity. That is the Stefan-Boltzmann law. There is no wavelength value in that.

Different materials, however, radiate differently at different wavelengths as temperature changes. This is where absorptivity comes in for different wavelengths.

Wein's law determines the wavelength at which a body's radiance is greatest for its temperature.

.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
15-08-2019 07:28
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
tmiddles wrote:My understanding is that ANYTHING, jelly donut, granite boulder, planet, will emitt exactly and only what it's temperature corresponds to....

Only the *power* (Radiance) is determined by the temperature and emissivity. That is the Stefan-Boltzmann law. There is no wavelength value in that....


I was thinking that it was 1 wavelength to 1 temperature. I see that a particular temp a "perfect black body" (from link)
is:


So at 300K there are emissions peak at 10 millibars but quite a bit above and below that.

Earth can look like this:


I thought that the curve was because not all the bits were the same temperature. The top graph though shows that even if they are you have a range of wavelengths right?

Or do different objects each do their own thing? Depending on emessivity?
Edited on 15-08-2019 07:29
15-08-2019 11:05
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
Wein's law determines the wavelength at which a body's radiance is greatest for its temperature.


So this is the same idea but it's not a single wavelength but a bell curve of them with the peak as determined by Wein:
Wien Law: (link
wavelength of peak (in Angstroms)= 3 x 107/T)
"The Wien Law gives the wavelength of the peak of the radiation distribution, while the Stefan-Boltzmann Law gives the total energy being emitted at all wavelengths by the blackbody"

15-08-2019 17:26
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:
IBdaMann wrote:
Wein's law determines the wavelength at which a body's radiance is greatest for its temperature.


So this is the same idea but it's not a single wavelength but a bell curve of them with the peak as determined by Wein:
Wien Law: (link
wavelength of peak (in Angstroms)= 3 x 107/T)
"The Wien Law gives the wavelength of the peak of the radiation distribution, while the Stefan-Boltzmann Law gives the total energy being emitted at all wavelengths by the blackbody"




I don't know the extent of your math proficiency but the best way to take in black body science is to start with Planck's law which is the base model on which black body science is built. It defines black bodies and builds in the laws of thermodynamics. Max Planck also explained what is going on with photons ... before they were called photons ... and then Einstein came along and claimed the Nobel prize for the concept.

Note: I had been asking you about the thermal feedback between a red hot 475degC steel inner ball and its 80degC outer shell. Planck's law explains how there is no such thing as a "thermal feedback" (yes, it was a trick question). The inner ball will go no higher than the 475degC. The outer shell can have no effect. It's the same with the earth's atmosphere; it cannot "warm" the surface. Planck's model answers this question.

Planck's law is a 2-parameter function of radiativity, i.e. it predicts the radiance (power per surface area) at a particular wavelength of a body at a particular temperature. This forms a familair graph of radiance over different wavelengths. You are, no doubt, familiar with the famous, nay, standard graph of Plank's for an ideal black body, i.e.:



Kirchoff's law tells us that absorptivity = radiativity, ... ergo Planck's, which graphs radiativity, also tells you absorptivity at a particular wavelength for a body at a particular temperature.

Note: this corroborates enforcement of the 2nd law of thermodynamics because photons of a particular wavelength of a cooler body will not be abosrbed by a body at a higher temperature.

Stefan-Boltzmann is the integral of Planck's over all wavelengths to get total radiance (power per surface area).

Wein's is the first derivative of Planck's, set to zero, to find the peak wavelength.

There's nothing mysterious.


.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
16-08-2019 00:06
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:I had been asking you about the thermal feedback between a red hot 475degC steel inner ball and its 80degC outer shell. Planck's law explains how there is no such thing as a "thermal feedback" (yes, it was a trick question). The inner ball will go no higher than the 475degC.

....

Kirchoff's law tells us that absorptivity = radiativity, ... ergo Planck's, which graphs radiativity, also tells you absorptivity at a particular wavelength for a body at a particular temperature.

Note: this corroborates enforcement of the 2nd law of thermodynamics because photons of a particular wavelength of a cooler body will not be abosrbed by a body at a higher temperature.


Yes I haven't forgottent he ball shell and have been working through that in the other thread. Also just put up a post that relates to this in the other thread.

So I'm crystal clear on the NET flow of thermal energy going from the hotter to the cooler in either conduction or radiance.

I'm now VERY confused by the prospect that a HOT body cannot absorb infrared radiation? Is that what cooler body wavelengths not being absorbed means? If so what happens to them? Don't they have to either pass through the hot body as though it was transparent or be reflected?
I thought the only 3 options were: Absorbed, Reflected, Pass through.

So if Object A is 500C and object B is 100C and they are right next to each other, two plates, and Object A is radiating out, 1/2 of it goes to the back, 1/2 of it runs right into object B. Now object B radiates, 1/2 of it goes out the front, half of it back toward Object A, but is passes through Object A?

..................A....B..................
...<----------A=>B..................
..................A<-B----->.........
...........<----A---B---------->...
..................A....B..................

Pretty sure I'm misunderstanding which is why I'm being specific.
16-08-2019 03:12
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:So I'm crystal clear on the NET flow of thermal energy going from the hotter to the cooler in either conduction or radiance.

Don't do this. You obviously did some research on one or more fanatical Marxist warmizombie websites. You can't say that I didn't warn you to stay away from them. This is a standard warmizombie manipulation.

This is what's going on. You found an article or site that sets gullible victims up to regurgitate a "net flow" argument. Global Warming dogma violates the laws of thermodynamics and warmizombies are forever pulling out their hair and gnashing their teeth at their inability to get around physics.

So the article/site assures the victim that Global Warming doesn't actually violate thermodynamics ... that it's perfectly OK for thermal energy from cooler objects to flow into warmer objects as long as the "net flow" is from the warmer to the cooler.

The gullible victim is then reassured that objections to Global Warming on the basis of thermodynamics violations are totally without merit because Global Warming is accomplished with the portion of the thermal energy that is allowed to violate thermodynamics, and that there is enough other thermal energy to ensure there is a "net flow" adhering to thermodynamics.

keepit wrote:I'm now VERY confused by the prospect that a HOT body cannot absorb infrared radiation?

No one said that. A very hot body can absorb infrared photons from an even hotter body (one of higher temperature) because the photons of the higher temperature body will have enough energy to become absorbed.

keepit wrote:I t half of it back toward Object A, but is passes through Object A?

The photons do not go through. They reflect.

.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
16-08-2019 03:57
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
Don't do this. You obviously did some research on one or more fanatical Marxist warmizombie ....
The photons do not go through. They reflect.
.


I did not and so far I'm not sure it makes a difference if there is net energy flow as they describe it or as you are.

There is a disturbing lack of clarity out there. I think our discussion so far wins.

So a photon=electro magnetic radiation= radiance just so I'm clear on that.

So that last bit is the important part I wasn't aware of:
If a photon has less energy than the temperature of what it's hitting it's reflected away?

So in the Ball/Shell you have the radiance coming from the ball and hitting the shell where it's absorbed. You than have what I call the "hand back" of the radiance coming from the shell to the ball, but this is simply reflected back instantly because of the temperature of the ball?
16-08-2019 04:37
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:There is a disturbing lack of clarity out there.

It's intentional misinformation for the purpose of preaching/converting to the Global Warming faith.

tmiddles wrote:So a photon=electro magnetic radiation= radiance just so I'm clear on that.

You can't use the "=". A photon is a discrete particle of electromagnetic radiation, which is a form of energy.

Radiance is an amount of electromagnetic radiation per unit time per a unit of surface area.

tmiddles wrote:So that last bit is the important part I wasn't aware of:
If a photon has less energy than the temperature of what it's hitting it's reflected away?

Your wording is off.

If you are citing the 2nd law of thermodynamics then you simply state that thermal energy flows from higher temperature to lower temperature and does not flow between bodies of the same temperature (important for thermal equilibrium). Thermal energy does not flow from lower temperature to higher temperature.

If you are citing Planck's law, photons from a body of lower energy state (temperature) are of insufficient energy to raise the energy state of a body of a higher energy state.

tmiddles wrote:So in the Ball/Shell you have the radiance coming from the ball and hitting the shell where it's absorbed. You than have what I call the "hand back" of the radiance coming from the shell to the ball, but this is simply reflected back instantly because of the temperature of the ball?

Yes, exactly ... except that it is not correct to say that the thermal energy is "reflected back." The energy is deflected in some way but the best wording is to simply state that it is not absorbed.

.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
16-08-2019 04:53
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
If you are citing Planck's law, photons from a body of lower energy state (temperature) are of insufficient energy to raise the energy state of a body of a higher energy state.


OK now that makes sense and I wasn't aware of it no.

A perfect black black body will absorb everything though right?

I guess if a perfect black body is white hot it's emitting bright white light. If some infrared radiation hit it then it would not be absorbed.

That's where the definitions collide for me.

Also I notice this is about the power of the photon not the wavelength right?
16-08-2019 05:28
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:A perfect black black body will absorb everything though right?

Nope.

First, it's "ideal" black body, not "perfect."

Second, ideal black bodies don't exist so I would be lying if I were to assert that "we know" how they behave.

Third, according to the science model, any ideal black body is of a particular temperature. If you have an ideal black body A at 60degC radiating into another ideal black body B at 80degC, B will not absorb thermal radiation from A, but A will be absorbing from B until the two reach thermal equilibrium.


tmiddles wrote: Also I notice this is about the power of the photon not the wavelength right?

Photons don't have power. Each photon represents a quantity of energy.

To have power you need a body that is radiating.

Power = Energy over time per surface area.


.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
16-08-2019 05:49
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
any ideal black body is of a particular temperature. If you have an ideal black body A at 60degC radiating into another ideal black body B at 80degC, B will not absorb thermal radiation from A,
Photons don't have power. Each photon represents a quantity of energy.


OK that helps. So basically radiance is going to behave exactly as conduction does, no swimming up stream.

Two scenarios trouble me:
If two plates of the same temperature are separated by a gap they will radiate back and forth in the gap right? The radiation cannot bounce off as it would not be absorbed by either plate and just bounce back and forth. And if same temp allows absorbtion what's the cut off in temp difference?

Is the "rate" or "intensity" of radiance effected by the presence of other radiance?

If a ball is at 500C in a void it radiates out at some rate x. If it's now surrounded by a shell at 400C then it won't radiate out, in the cooling down sense, as it would otherwise. How is the cooler shell influencing the radiance out of the ball if it's not able to have it's radiation absorbed by it?
16-08-2019 21:17
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:OK that helps. So basically radiance is going to behave exactly as conduction does, no swimming up stream.

Correct.

tmiddles wrote: Two scenarios trouble me:
If two plates of the same temperature are separated by a gap they will radiate back and forth in the gap right? The radiation cannot bounce off as it would not be absorbed by either plate and just bounce back and forth.

No. Photons are not little rubber boucy-balls. This might be a little disappointing but we don't have science that predicts exactly what photons do in every situation. Photons reflect, deflect, become absorbed, interact and other things we can't imagine because we cannot see individual photons and we cannot account for each one.

This is why it is best to simply state the specific negative, that photons from a cooler body are not absorbed by the warmer body. That, at least, is correct. That is something that we can list under "that which we know." Identifying exactly what does happen to each and every photon we cannot list under "that which we know." This means that you are free to speculate just like everyone else, and your thoughts are just as valid as anyone else's as long as you don't claim that photons from a cooler body are being absorbed by a warmer body.

I'd like to return to my comment concerning photons not being bouncy-balls. They actually do behave like bouncy-balls ... and they absolutely do not behave as bouncy-balls. The moment you shift your context from the macro world (bodies, familiar objects, planets, two plates of the same temperature, etc..) to the quantum world (electrons, photons, elementary particles, etc..) nothing actually applies because the quantum world doesn't behave as the macro world. We run a certain risk whenever we try to apply macro world references, e.g. "bouncing back and forth" to quantum world scenarios.

If you aren't familiar with the double-slit experiment, you should become familiar with it to better understand what you need to consider when you traverse contexts.

https://www.youtube.com/watch?v=DfPeprQ7oGc

... and to this end, do yourself a favor and do a quick read on the Heisenberg Uncertainty Principle. If you don't understand that then you'll get lost on a lot of stuff in the quantum world.

tmiddles wrote:Is the "rate" or "intensity" of radiance effected by the presence of other radiance?

If you watched the above video then you know that in the quantum world there is interference and cancelation. In the macro world, you can get a good idea of this if you put two different transmission antennae from two different systems too close to each other. However, this is just one example. In the quantum world, there can be many types of effects that don't have macro world equivalents.

tmiddles wrote: If a ball is at 500C in a void it radiates out at some rate x. If it's now surrounded by a shell at 400C then it won't radiate out, in the cooling down sense, as it would otherwise.

Sure it will. The ball is of a higher temperature than the shell so the ball will radiate into the shell, increasing the shell's temperature. The shell, being of a lower temperature, will not increase the temperature of the ball.

.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
17-08-2019 00:33
Into the NightProfile picture★★★★★
(9597)
tmiddles wrote:
IBdaMann wrote:
any ideal black body is of a particular temperature. If you have an ideal black body A at 60degC radiating into another ideal black body B at 80degC, B will not absorb thermal radiation from A,
Photons don't have power. Each photon represents a quantity of energy.


OK that helps. So basically radiance is going to behave exactly as conduction does, no swimming up stream.

The same is true for convective heating. No swimming upstream.
tmiddles wrote:
Two scenarios trouble me:
If two plates of the same temperature are separated by a gap they will radiate back and forth in the gap right? The radiation cannot bounce off as it would not be absorbed by either plate and just bounce back and forth.

No. Not all photons emitted are the same frequency. Not all molecules in either plate are either. There will some absorption by some molecules, and all molecules will be emitting at various frequencies.
tmiddles wrote:
And if same temp allows absorbtion what's the cut off in temp difference?

Zero, if and only if all molecules are exactly the same temperature (they never are).
tmiddles wrote:
Is the "rate" or "intensity" of radiance effected by the presence of other radiance?

No.
tmiddles wrote:
If a ball is at 500C in a void it radiates out at some rate x.

I recently used a ball at 1600 deg F, but...meh.
tmiddles wrote:
If it's now surrounded by a shell at 400C then it won't radiate out,

It was surrounded by a shell at 22 deg C because I fired the fuse to blow it up. The ball in the center radiated out and heated the shell to 1600 deg C, you see.
tmiddles wrote:
in the cooling down sense, as it would otherwise.

Everything cooled off afterwards, just like normal.
tmiddles wrote:
How is the cooler shell influencing the radiance out of the ball if it's not able to have it's radiation absorbed by it?

The cooler shell DOES absorb the ball's radiance. Quite rapidly too in this case.

The effect was spectacular. People watching it liked it. Of course, the car the ball was put into didn't fare so well. I have a nice video of the rear door flying away about 50 ft.

We called the junk yard and told them they could have it back now that we were through with it.


The Parrot Killer
Edited on 17-08-2019 00:38
17-08-2019 00:57
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
tmiddles wrote:OK that helps. So basically radiance is going to behave exactly as conduction does, no swimming up stream.

Correct.


I think this is really a key to move on from. If the results of radiance and the results of conduction with interacting matter have the same behavior than it makes it a lot simpler.

Also the "global warming"(magazine article headline identification purposes) talk of "radiating down" really tell the reader there is new energy somehow. Since the behavior is no different than conduction this is pointlessly misleading (or deliberately misleading!)

I think ITN was mentioning at one point that my sweater is not heating me, it generates no thermal energy. It's simply acting as an insulator and "reducing heat" for my body to the surroundings.

IBdaMann wrote:

https://www.youtube.com/watch?v=DfPeprQ7oGc

... and to this end, do yourself a favor and do a quick read on the Heisenberg Uncertainty Principle. If you don't understand that then you'll get lost on a lot of stuff in the quantum world.


The whole thing is so hard to grasp based on my own experience it's really frustrating. That video is great but the subject is so hard to get. The observer thing I mean, the rest is fascinating and makes sense.

Also I don't really understand what the Heisenberg Uncertainty Principle is ( I read it just don't get it ).

There was a movie, what the bleep do we know:
https://www.imdb.com/title/tt0399877/
I really hated and I'm pretty sure it's garbage. Have you seen it? Deals with the uncertainty principle but a lot of other BS (like poetry showing up in ice).

IBdaMann wrote:
tmiddles wrote: If a ball is at 500C in a void it radiates out at some rate x. If it's now surrounded by a shell at 400C then it won't radiate out, in the cooling down sense, as it would otherwise.

Sure it will.


But it's heat is reduced by the shell and it will take longer for it to radiate out to drop in temperature right? It is insulated by the shell to a degree correct?

But no differently than a ball with a shell that it's in physical contact with so it's conduction instead of radiance.
17-08-2019 01:13
tmiddlesProfile picture★★★★☆
(1327)
Into the Night wrote:
The same is true for convective heating. No swimming upstream.


I find that the easiest to visualize since it's an actual flow of matter that would push other matter out of the way.

Into the Night wrote:
tmiddles wrote:
And if same temp allows absorbtion what's the cut off in temp difference?

Zero, if and only if all molecules are exactly the same temperature (they never are).


Ah right good reminder that it's always some kind of mix.

Into the Night wrote:
tmiddles wrote:
Is the "rate" or "intensity" of radiance effected by the presence of other radiance?

No.


So if I have object A at 500C butted up against some object C at 100C it will conduct out from A to C. If object A is directly next to a void it will radiate out.

If I place object B at 300C inbetween object A and object C then object B will reduce the heat of A and insulate it from C, the conduction would be reduced from A to C by B. If object B is inbetween object A and the void, not touching, what happens with A's radiance? It would also have reduced heat right? It would simply take longer for the thermal energy to drop with B in the way than without it there correct?

Into the Night wrote:I have a nice video of the rear door flying away about 50 ft.


Post it if you can!
17-08-2019 02:00
Into the NightProfile picture★★★★★
(9597)
tmiddles wrote:
IBdaMann wrote:
tmiddles wrote:OK that helps. So basically radiance is going to behave exactly as conduction does, no swimming up stream.

Correct.


I think this is really a key to move on from. If the results of radiance and the results of conduction with interacting matter have the same behavior than it makes it a lot simpler.

Also the "global warming"(magazine article headline identification purposes) talk of "radiating down" really tell the reader there is new energy somehow. Since the behavior is no different than conduction this is pointlessly misleading (or deliberately misleading!)

It is being deliberately misleading. You cannot heat a warmer surface using a colder gas. You cannot make heat flow backwards. The article is denying the 2nd law of thermodynamics.
tmiddles wrote:
I think ITN was mentioning at one point that my sweater is not heating me, it generates no thermal energy. It's simply acting as an insulator and "reducing heat" for my body to the surroundings.

Actually, FROM your body to the surroundings. Sweaters don't even make you warmer. Your body heat is controlled by your own body automatically for you. All a sweater does it allow you to do that by consuming less food. Of course, you body can only consume so much food in a given time, so if it's cold enough, your body temperature will drop without a sweater. In that case, your body simply cannot consume enough food fast enough to maintain your own body temperature. This condition is called hypothermia and is a very dangerous condition that is life threatening and needs IMMEDIATE treatment.

In most cases where you would want to use just a sweater, you will feel chilly, but you will be able to cope without the sweater and still maintain your body heat.

tmiddles wrote:
IBdaMann wrote:

https://www.youtube.com/watch?v=DfPeprQ7oGc

... and to this end, do yourself a favor and do a quick read on the Heisenberg Uncertainty Principle. If you don't understand that then you'll get lost on a lot of stuff in the quantum world.


The whole thing is so hard to grasp based on my own experience it's really frustrating. That video is great but the subject is so hard to get. The observer thing I mean, the rest is fascinating and makes sense.

Heh. It's a bit screwy looking to say the least. Basically, all that Heisenberg is saying is that for subatomic particles (he was addressing electrons as an example when he said this), you can either know where the particle is, or you can know how fast it's moving, but not both. This principle is a mathematical one in nature, and essentially ends up describing any photon, neutron, proton, or electron, or even the atom itself as a wavelet...a kind of localized set of waves (which has the properties of speed and frequency), and a particle (which has the properties of location in space). It is essentially neither. All matter is can be represented by a wavelet.

It becomes a wave when you consider a moving particle and the particle looks more like a single frequency.
It becomes a band of frequencies, centered around some center frequency, when you try to determine it's location in space. It's in there somewhere.

No rubber balls. No little miniature solar system like constructs for the atom (otherwise known as the Bohr model of the atom, the kind shown in crappy textbooks). No orbits for electrons. They have orbitals instead. The electron is in there somewhere, but we don't know where. We know it's average shape of orbital for each level of energy, but it's only an average.

As Stephan Hawking once remarked, "God not only rolls dice, he rolls them where you can't see them!". This quote was talking about astronomy, but it certainly pertains to the weird world of quantum physics!


The Parrot Killer
17-08-2019 02:11
Into the NightProfile picture★★★★★
(9597)
tmiddles wrote:
Into the Night wrote:
The same is true for convective heating. No swimming upstream.


I find that the easiest to visualize since it's an actual flow of matter that would push other matter out of the way.
tmiddles wrote:
Into the Night wrote:
[quote]tmiddles wrote:
And if same temp allows absorbtion what's the cut off in temp difference?

Zero, if and only if all molecules are exactly the same temperature (they never are).


Ah right good reminder that it's always some kind of mix.

Yup. Always good to remember.
tmiddles wrote:
Into the Night wrote:
tmiddles wrote:
Is the "rate" or "intensity" of radiance effected by the presence of other radiance?

No.


So if I have object A at 500C butted up against some object C at 100C it will conduct out from A to C. If object A is directly next to a void it will radiate out.

If I place object B at 300C inbetween object A and object C then object B will reduce the heat of A and insulate it from C, the conduction would be reduced from A to C by B.

A's blackbody radiance is not determined by any nearby body. It is solely determined by the Stefan-Boltzmann law, which relates temperature to radiance (conversion of thermal energy to electromagnetic energy).
tmiddles wrote:
If object B is inbetween object A and the void, not touching, what happens with A's radiance?

Nothing.
tmiddles wrote:
It would also have reduced heat right?

Nope. A can easily heat B by radiance.
tmiddles wrote:
It would simply take longer for the thermal energy to drop with B in the way than without it there correct?

Nope. It's easier. B is closer than C. The light that intercepts any object when radiating from a point source (such as A) is reduced by the inverse square law with distance. This law holds true for anything radiating from a point source, whether it's photons, bullets, or debris from an explosion. Distance is your friend when working with explosives or being confronted by a deranged shooter!
tmiddles wrote:
Into the Night wrote:I have a nice video of the rear door flying away about 50 ft.


Post it if you can!

Plan to. I have to get a better computer setup before I can get it into a form where I can post it. Frankly, I am surprised that no one has posted it already. We had a lot of photographers there with better equipment than mine, including a drone camera.

BTW, the size of the sphere I used was about 3 inches across and was filled with black powder and titanium.


The Parrot Killer
Edited on 17-08-2019 02:16
17-08-2019 03:19
tmiddlesProfile picture★★★★☆
(1327)
Into the Night wrote:
tmiddles wrote:
If object B is inbetween object A and the void, not touching, what happens with A's radiance?

Nothing.


Isn't the rate at which temperature drops reduced by the presence of another object nearby? It is with conduction and I thought radiance behaved the same way.
17-08-2019 03:36
Into the NightProfile picture★★★★★
(9597)
tmiddles wrote:
Into the Night wrote:
tmiddles wrote:
If object B is inbetween object A and the void, not touching, what happens with A's radiance?

Nothing.


Isn't the rate at which temperature drops reduced by the presence of another object nearby? It is with conduction and I thought radiance behaved the same way.


No. Radiance does not follow Fourier's conduction law. It follows the Stefan-Boltzmann law. Nearby objects make no difference at all.

Light is not heat. It can be a medium of heating, but it in and of itself is not heat.

It takes energy to radiate light. That energy can come from thermal energy (i.e. the Stefan-Boltzmann law). Emitting light in and of itself cools the primary object. It is also not the only way to generate light. ANY method of generating light requires energy.

Radiance is heat. It is heat to some far away body or it is heat to a nearby body. It doesn't matter.

Light is not in and of itself heat. It is a medium. It will continue to travel through space until it is absorbed by something. Sooner or later, it WILL hit something that will absorb it. Light is little packets of energy streaming away from whatever generated them.

They are not rubber balls. They are not all the same amount of energy. Remember Heisenberg's Uncertainty Principle and Planck's law.


The Parrot Killer
17-08-2019 04:35
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:
If the results of radiance and the results of conduction with interacting matter have the same behavior than it makes it a lot simpler.

Conduction and black body radiation are not the same thing. They have the same "results" insofar as adhering to the 2nd law of thermodynamics but I spelled out the differences along with the similarities.

tmiddles wrote:I think ITN was mentioning at one point that my sweater is not heating me, it generates no thermal energy. It's simply acting as an insulator and "reducing heat" for my body to the surroundings.

Correct. Specifically, the sweater reduces conduction because the sweater has a low thermal coefficient. Your body's radiance, however, remains unaffected because your radiance into the sweater is dependent only on your absolute temperature. The sweater doesn't somehow alter your body's emissivity.

tmiddles wrote:The whole thing is so hard to grasp

Nope. I'm not buying it. Children easily understand it.

In the quantum world, the act of measuring an elementary particle alters the particle measured. Ergo, whatever your measurements read, that's what it isn't. The more you measure just to be sure, the more surely it isn't what you measure.

The Heisenberg Uncertainty Principle specifically states that the more you know about a particle's position, the less you know about its momentum, and the more you know about its momentum, the less you know about its position.

Let's say you fire photons that will deflect off an electron and be captured by a sensor, telling you where the electron is. Well, the act of pummeling the electron with photons changes the electron's path so when you calculate an extrapolation of where the electron is one microsecond later, all you can be certain of is that it is not there.

As you noticed, people like to treat physics like it's mysterious, and they can't resist the urge to take literary license when describing the quantum world. One of the most common examples is to refer to "an observer" instead of saying "take a measurement." It's intuitive to understand how the act of measuring affects elementary particles but people find it more interesting to make physics seem mysterious and instead imply that the mere act of observing somehow changes the behavior of elementary particles.

tmiddles wrote:But it's heat is reduced by the shell and it will take longer for it to radiate out to drop in temperature right? It is insulated by the shell to a degree correct?

No. The shell, being of the same material, has the same thermal coefficient of conduction and the same emissivity as the ball.

Conduction is thermal energy flow through physical contact of matter. A substance is considered "insulation" in conduction if its thermal coefficient is "low."

Thermal radiance, however, is dependent only on temperature. A substance is considered "insulation" in thermal radiation if its emissivity is "low."


.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
17-08-2019 11:42
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
Thermal radiance, however, is dependent only on temperature. A substance is considered "insulation" in thermal radiation if its emissivity is "low."
.


This question is split between two topics. Easier to keep it here: link

And I don't think school children have no trouble with the observation of an electron changing it's movement from a wave to a particle. It's freaky.
17-08-2019 17:07
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:
And I don't think school children have no trouble with the observation of an electron changing it's movement from a wave to a particle. It's freaky.

Children have no trouble whatsoever because electrons and photons don't change behavior between particles and waves. You have allowed yourself to become confused even though I warned you in advance.

Elementary particles in the quantum world act as both waves and particles. Waves are simple macro world references that we humans can understand. Bouncy-balls are simple macro world references that we humans can understand. In the quantum world, there are no bouncy-balls and no beaches. Elementary particles are unlike anything we can experience in our macro world.

So the result is that you think that's "freaky." That does not mean that children have a difficult time understanding concepts when properly explained.

Once I was with some little-leaguers when we had an opportunity to throw baseballs against a backstop machine that registered how fast a baseball was traveling when it hits the machine (it wasn't a radar gun, you throw the ball at it). After a while of letting the kids throw at it to see how fast they threw, I asked the kids if the machine worked. They all said yes. I asked them if they were sure. They said that they had been using it. I asked one kid to throw a ball at the machine. It registered 51 mph. I pointed to the baseball on the ground and said "the machine says this baseball is going 51 mph but it's not moving. I don't think the machine is working." The kids laughed and told me that the ball was moving that fast but it hit the machine and stopped. I asked if the machine should be telling me "zero" instead of "51" and they said no, that they wanted to know how fast it was going, not how fast after it was stopped.

I did not mention to them that they had just learned the Heisenberg Uncertainty Principle but they had.





.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
18-08-2019 04:47
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:they said no, that they wanted to know how fast it was going, not how fast after it was stopped.


Cool analogy.

I'm getting that being confused about conflicting references to something isn't the same as being confused about the something.

I guess if I told someone that money was like energy and the economy worked like an engine, things could go south pretty fast as they asked about how a fiat currency related to coal.

The freaky bit for me was in that video how the spray pattern of electrons changed with a measuring device being present.
18-08-2019 05:13
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:The freaky bit for me was in that video how the spray pattern of electrons changed with a measuring device being present.

That part bothered me, i.e. the way they portrayed the electrons as being sneaky, sentient beings that "knew" they were being "observed" and intentionally screwed with the test results.



In the double slit experiment, the only way to observe/measure the electrons causes interference which alters the resulting pattern. It's the intrusion of the act of measuring that alters the results, not the mere act of "observing." I hate deceit in the name of generating interest in otherwise boring material.

If you want more examples of this sort of crap, try reading about "Schroedinger's Cat" and "The Copenhagen Interpretation." They are both straightforward concepts that children can understand ... but you won't be able to really figure them out judging by how people write about them.

Give it a try. If you're not getting it, feel free to blame the writer of incompetence and of dishonestly hyping what is otherwise common sense until it is not fully understandable.


.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
18-08-2019 05:36
tmiddlesProfile picture★★★★☆
(1327)
IBdaMann wrote:
If you want more examples of this sort of crap, try reading about "Schroedinger's Cat"


Oh yeah! Schroedinger tries to point out the absurdity of something only to have is joke used as an example. I know that one well.
18-08-2019 05:58
IBdaMannProfile picture★★★★★
(4926)
tmiddles wrote:
IBdaMann wrote:
If you want more examples of this sort of crap, try reading about "Schroedinger's Cat"


Oh yeah! Schroedinger tries to point out the absurdity of something only to have is joke used as an example. I know that one well.


... and to have millions of people name their cats "Schroedinger" ... and think they're being original.


Global Warming: The preferred religion of the scientifically illiterate.

Printing dollars to pay debt doesn't increase the number of dollars. - keepit

When the alt-physics birds sing about "indivisible bodies," we've got pure BS. - VernerHornung

Ah the "Valid Data" myth of ITN/IBD. - tmiddles

Ceist - I couldn't agree with you more. But when money and religion are involved, and there are people who value them above all else, then the lies begin. - trafn

You are completely misunderstanding their use of the word "accumulation"! - Climate Scientist.

The Stefan-Boltzman equation doesn't come up with the correct temperature if greenhouse gases are not considered - Hank

:*sigh* Not the "raw data" crap. - Leafsdude

IB STILL hasn't explained what Planck's Law means. Just more hand waving that it applies to everything and more asserting that the greenhouse effect 'violates' it.- Ceist
19-08-2019 09:11
Into the NightProfile picture★★★★★
(9597)
IBdaMann wrote:
tmiddles wrote:
And I don't think school children have no trouble with the observation of an electron changing it's movement from a wave to a particle. It's freaky.

Children have no trouble whatsoever because electrons and photons don't change behavior between particles and waves. You have allowed yourself to become confused even though I warned you in advance.

Elementary particles in the quantum world act as both waves and particles. Waves are simple macro world references that we humans can understand. Bouncy-balls are simple macro world references that we humans can understand. In the quantum world, there are no bouncy-balls and no beaches. Elementary particles are unlike anything we can experience in our macro world.

So the result is that you think that's "freaky." That does not mean that children have a difficult time understanding concepts when properly explained.

Once I was with some little-leaguers when we had an opportunity to throw baseballs against a backstop machine that registered how fast a baseball was traveling when it hits the machine (it wasn't a radar gun, you throw the ball at it). After a while of letting the kids throw at it to see how fast they threw, I asked the kids if the machine worked. They all said yes. I asked them if they were sure. They said that they had been using it. I asked one kid to throw a ball at the machine. It registered 51 mph. I pointed to the baseball on the ground and said "the machine says this baseball is going 51 mph but it's not moving. I don't think the machine is working." The kids laughed and told me that the ball was moving that fast but it hit the machine and stopped. I asked if the machine should be telling me "zero" instead of "51" and they said no, that they wanted to know how fast it was going, not how fast after it was stopped.

I did not mention to them that they had just learned the Heisenberg Uncertainty Principle but they had.





.


Well described!


The Parrot Killer




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