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Just Chat! / Re: Is there a universal moral standard?

« Last post by alancalverd on Today at 22:34:14 »

You just said that you don't share their goal and world view.

The end does not necessarily justify the means.

I can share the goal of living in heaven for ever. I might even agree that it can be achieved by killing others. But the action still fails the moral test because I wouldn't like anyone to kill me, and I wouldn't like to kill my nearest and dearest.

Tomorrow I will be sitting on a research ethics committee. Suppose ypou came up with a plausible method for curing glioblastoma, but the only way of proving its effectiveness would involve killing a dozen healthy teenagers. You might convince the committee that the end is worthwhile (we wouldn't take much convincing) and that the means has a sound scientific rationale. So, as well-motivated and informed professionals, we share your goal and world view. But would we approve the project? I think not.

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Just Chat! / Re: Is there a universal moral standard?

« Last post by alancalverd on Today at 22:18:08 »

Who should take the tests?

What matters in this instance is who should apply the tests to the proposed action. 

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Just Chat! / Re: Is there a universal moral standard?

« Last post by alancalverd on Today at 22:16:52 »

Priests tell you to believe things that can't be seen or tested, then to base your behavior on their interpretation of whatever they told you to believe. How can that be good? A broken clock is occasionally right, but never to be trusted.

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Just Chat! / Re: Would you "cancel" a family member or a good friend?

« Last post by alancalverd on Today at 22:11:56 »

Friendship is not a matter of contract, nor do family ties imply enduring tolerance.

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Physics, Astronomy & Cosmology / Re: Do you change the spectrum of radiation inside an oven if you change its shape?

« Last post by Bored chemist on Today at 17:56:10 »

What's the metal?

I don't know. There's not enough information to distinguish one from the others.

Let's apply some basic logic.
Cameras can distinguish between absorption spectrum of gold and silver.
Cameras cannot distinguish between emission spectrum of gold and silver.
Conclusion: emission spectrum can be different from absorption spectrum.

Let's apply some less basic logic.
Correct conclusion:
The camera doesn't have good enough colour rendering when faced with something that bright.
It is further doomed to failure because the temperatures are different.

Just because a particular piece of equipment is not sensitive enough to detect an effect, that does not mean that the effect is not there. It means you ae not using the right equipment.

All the spectroscopists know about Kirshhoff, so there's no reason to keep citing the details.
Everyone knows that an absorption spectrum typically looks like an emission spectrum.

So, they only publish examples of  the interesting cases where the rule doesn't apply- for example- with fluorescence.

Unfortunately, that means that, if you look at the publications, they will mislead you into thinking that the the spectra are usually different.

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Physics, Astronomy & Cosmology / Re: Do you change the spectrum of radiation inside an oven if you change its shape?

« Last post by Bored chemist on Today at 17:50:12 »

Kirchoff's Law of Radiation
At a given temperature, the ratio of the emissive power of a body to its absorptive power is constant and is equal to the emissive power of a black body at the same temperature.

OK.
So, it's true at any temperature.
So that means it's true when the object is red hot- mainly emitting red and IR. And it's also true when the object is so hot that it's emitting blue light.
For it to be true regardless of what wavelengths are being emitted, it must be true at all wavelengths individually.
So the spectra must be the same.
(Unless you pick something weird like a fluorescent material)

So why have you chosen to pretend that Ti doped sapphire  is similar to molten metal?

(Incidentally, if you don't disperse the Ti+++ ions into a sapphire lattice, you get Ti2O3 which is black)

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Physics, Astronomy & Cosmology / Re: Do you change the spectrum of radiation inside an oven if you change its shape?

« Last post by Bored chemist on Today at 17:42:32 »

What's the metal?

I don't know. There's not enough information to distinguish one from the others.

But you said there was.

They are good enough to distinguish the absorption spectrum of gold from silver. If their difference in emission spectrum of gold and silver is proportional to the difference in absorption spectrum, then cameras and TV screens should be able to distinguish them as well.

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Physics, Astronomy & Cosmology / Re: Do you change the spectrum of radiation inside an oven if you change its shape?

« Last post by hamdani yusuf on Today at 17:38:21 »

What's the metal?

I don't know. There's not enough information to distinguish one from the others.

Let's apply some basic logic.
Cameras can distinguish between absorption spectrum of gold and silver.
Cameras cannot distinguish between emission spectrum of gold and silver.
Conclusion: emission spectrum can be different from absorption spectrum.

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Physics, Astronomy & Cosmology / Re: Do you change the spectrum of radiation inside an oven if you change its shape?

« Last post by hamdani yusuf on Today at 17:31:56 »

The conservation of energy.
You keep trying or pretend that Kirchhoff's law doesn't exist.

This is not Kirchhoff's law.

The material is not fluorescing, undergoing a chemical reaction or exhibiting nuclear decay.
So Kirchhoff's law applies.
The absorption spectrum is the same as the emission spectrum.

This is.

Kirchoff's Law of Radiation
At a given temperature, the ratio of the emissive power of a body to its absorptive power is constant and is equal to the emissive power of a black body at the same temperature.

Alternative statement of Kirchhoff's law: At any given temperature, the emissivity of a body is equal to its coefficient of absorption.

https://www.toppr.com/ask/content/concept/kirchoffs-law-of-heat-radiation-and-its-theoretical-proof-209979/

The absorption spectrum is the same as the emission spectrum for low pressure gases. But for other type of materials, it doesn't generally apply, as shown in a counterexample here.

Take a look at this.

1. Schematic diagram of absorption and emission spectra of Ti 3+ as impurities in a sapphire. 
https://www.researchgate.net/figure/Schematic-diagram-of-absorption-and-emission-spectra-of-Ti-3-as-impurities-in-a_fig3_48308616

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Physics, Astronomy & Cosmology / Re: Do you change the spectrum of radiation inside an oven if you change its shape?

« Last post by Bored chemist on Today at 17:24:25 »

What's the metal?