The excellent answers to the question Why do metals only glow red, yellow and white and not through the full range of the spectrum? are valuable and helpful.

I'm not sure why this question should be considered a duplicate of What causes a black-body radiation curve to be continuous? These answers do not seem to address the other question at all, and pointing readers to these answers may cause them to miss the better answers there.

Should this really be marked as duplicate like this?

I don't have enough rep to re-open it, hopefully someone else will get the ball rolling.

@EmilioPisanty has noted that the question What would the RGB color value of an infinitely hot blackbody be? is related, but the question I am asking about has so many high quality answers I think it should not be pointed to this question either.


1 Answer 1


Important note: whether two questions are duplicates depends on the questions, not the answers.

The first question, which is currently marked as a duplicate of the other, asks

Why don't metals glow from red to yellow to green to blue etc.? Why only red, then yellow and then white? Shouldn't all wavelengths be emitted one by one as the temperature of the metal increases?

If some metals do glow at with different colours, could you give me examples of such metals and the reason why this happens in specific cases?

And the second question asks (at its core)

I am wondering what exactly gives rise to a basically continuous black-body radiation curve in real objects? Since atomic energy states are quantized, it seems real life black-body curves would have some degree of measurable quantization to them (or perhaps the degree of quantization is so small the radiation curves look continuous).

The first one is about how an object's blackbody spectrum changes as its temperature changes, and the second is about a spectrum at a fixed temperature, namely why there are no "holes" in the spectrum due to quantization. These are quite different and on that basis I agree that there should not be a duplicate relationship.

I'd note that the first question also goes on to explain what makes it different from the other one. That is, in general, the recommended way for the question author to respond to the question being marked as a duplicate when they believe it shouldn't be. But in this case I think it's clear even without that explanation that these are different questions. Unfortunately, the edit was done in such a way that it's not going to make a whole lot of sense after the duplicate mark is reversed, so that question is going to need either a rollback or some further editing.

I'll leave this here for a few hours to see if anyone raises mitigating factors, but if not, I'll undo the duplicate mark and make the necessary edits.

  • $\begingroup$ Thanks for your consideration. I should have made it clearer in my question that my concern about pointing away from the quality answers was a "why this matters" rather than a dupe/nodupe factor. $\endgroup$
    – uhoh
    Commented Apr 6, 2018 at 4:45

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