I am familiar with the physical facts you’ve described in this comment. But, what seems to be the case is that you are confused about what color is.
For example:
Of course, we do know that it emits purple photons.
There is no such thing as “purple photons”. (If you doubt this, consider whether there’s such a thing as “magenta photons”—and if not, why not, if there can be “purple photons”—and also whether, when you look at a picture of an orange on your computer, the computer’s screen is emitting “orange photons”.)
Ah, or maybe you’re expecting me to know that you mean something like “What if the atom is only purple because it’s being ‘blasted’ with purple photons, making this photo useless in terms of understanding its color?” That’s a reasonable thing to think if you’ve never had reason to study atomic spectra, but it turns out the direction of causation is just the opposite—scientists chose a purple laser because that’s one of the few colors the atom would absorb and re-emit.
What would the atom look like in ordinary illumination (say, sunlight at noon, or a flourescent light, or any other common lighting conditions)? Would it also look purple?
Even when I argue that things invisible to the planet eye, like the planet Neptune, can have color, it’s not necessarily because of complicated sciencey reasoning, but more some heuristic arguments about process that preserve color. You can look at Neptune through a telescope and it has color then—so since telescopes preserve color, Neptune is blue. Or if I took a red teapot and shot it into space somewhere between the orbit of Mars and Jupiter and we never saw it again, it would still be red, because in color-logic, moving something somewhere else is a process that preserves color.
In short, I didn’t bother to actually do the math on whether you could see an atom with the naked eye until today because I think of time lapse photography or using lenses to look at something as process that preserve “intuitive color.”
There is no fact of the matter about whether Neptune “is blue”. The physical facts which sentences like “a tomato is red” or “a banana is yellow” cash out into, are inapplicable to Neptune. We could say that Neptune “looks blue when viewed with the naked eye from Earth”—which would be false, because Neptune cannot be seen with the naked eye from Earth. We could also say that Neptune “looks blue when viewed through a telescope from Earth”—which would be true.
So, is a strontium atom purple? Well, let’s table that. Does a strontium atom look purple when viewed with the unaided naked eye in ordinary terrestrial lighting conditons? No; it cannot be seen with the unaided naked eye. (Right? Or do you say that it can?) Does a strontium atom look purple when subjected to laser light of a certain frequency, etc.? No; it still cannot be seen with the unaided naked eye, even then. Does a picture of a strontium atom which has been subjected to certain light etc., taken with a certain sort of long-exposure camera, etc., look purple? Clearly, yes.
Maybe you read this as something like “We’re not actually seeing the atom, we’re just seeing ‘a glow created by the atom’ that’s a lot bigger than the atom, therefore this isn’t a picture of the atom.” That’s false. This goes back to why I was making fun of the reporter who said “We’re not seeing the atom, we’re just seeing the light emitted by the atom.” Seeing the light emitted by something is what seeing is.
(This part is also confused, but I defer commenting on it, as I would like you to address the other things I’ve said in this comment and prefer to avoid distractions; I merely note it for the record.)
(I’m coming to this rather late, and will entirely understand if Said doesn’t want to resurrect an old discussion; if not, I hope no reader will take the lack of response to indicate that my points were just so compelling that Said had no answer to them.)
There is no such thing as “purple photons” [...]
I am unconvinced by your argument here (which may just indicate that I haven’t grasped what it is). The following position seems pretty reasonable to me: There are violet photons but not magenta photons. There are orange photons, but because of metamerism you can see something orange without any orange photons being involved. Violet photons are not violet in the same way as a piece of paper covered in violet dye is violet, but it’s reasonable to use the same word for both.
Would you care to make more explicit your reasons for saying that there is no such thing as a violet photon? (You actually said purple, as Charlie had done in the comment you were replying to, but I’m fairly sure your position is not “there are photons of some colours but not of others”. My apologies if I’ve misunderstood.)
What would the atom look like in ordinary illumination [...]
Like many things, it would look different in different conditions of illumination. Unlike most things we look at, its spectrum is composed of a few sharp peaks, so the relationship between its illumination and the colour we see (given sufficient “amplification” since of course a single atom can neither emit nor scatter very much light) is a bit unusual. (One can make macroscopic materials with similar properties and I don’t see any particular reason to deny that they have colour.)
There is no fact of the matter as to whether Neptune “is blue”. [...]
This seems like a matter of definitions, and I don’t like your definitions. Whatever difficulties there are about assigning a colour to Neptune are simple a consequence of the fact that it’s a long way away from us. (I think it’s clear that there’s a fact of the matter as to whether Mars is red: it is. If Neptune’s orbit were where Mars’s is, there’d be no difficulty saying that Neptune is blue.) Are you sure you want to say that whether a thing has a definite colour can change merely on account of the distance between it and us? If we sent astronauts to Neptune instead of just probes, would there then be a fact of the matter as to whether Neptune has a colour? If there were an accident and the astronauts died, would Neptune’s colour-having-ness change? If I take an orange, lock it in a vault (illuminated, let’s say, by an incandescent bulb in the vault), and throw away the key, does there stop being a fact of the matter as to whether the orange is orange?
Incidentally: yes, the reporter is wrong about something. A quarter of a nanometre is not 2.5 x 10^-7 metres.
Well, you are free to use the word “color” in such a way that there is no fact of the matter about whether Neptune has a color if you wish. But I think that this directs us into a definitional argument that I don’t feel like having—in fact, almost a perfect analogy to “If a tree falls in a forest and there’s no one to hear it, does it make a sound?”
No, this isn’t a definitional argument. Insofar as your view leads you to misunderstand very real facts about human color perception, it is mistaken. Again, consider the questions I asked about “photon color” at the start of the grandparent comment.
This sort of misconception is quite common, especially among mathematically or physically inclined folks who have not studied color theory and the psychophysics of color. It leads, unfortunately, to mistakes in the design and implementation of various systems that have to use or manipulate color in one way or another.
It’s certainly your right to tap out of the conversation. But I hope that you’ll consider what I’ve said (and the same goes for anyone else reading this exchange who feels that Charlie Steiner’s perspective makes sense).
I am familiar with the physical facts you’ve described in this comment. But, what seems to be the case is that you are confused about what color is.
For example:
There is no such thing as “purple photons”. (If you doubt this, consider whether there’s such a thing as “magenta photons”—and if not, why not, if there can be “purple photons”—and also whether, when you look at a picture of an orange on your computer, the computer’s screen is emitting “orange photons”.)
What would the atom look like in ordinary illumination (say, sunlight at noon, or a flourescent light, or any other common lighting conditions)? Would it also look purple?
There is no fact of the matter about whether Neptune “is blue”. The physical facts which sentences like “a tomato is red” or “a banana is yellow” cash out into, are inapplicable to Neptune. We could say that Neptune “looks blue when viewed with the naked eye from Earth”—which would be false, because Neptune cannot be seen with the naked eye from Earth. We could also say that Neptune “looks blue when viewed through a telescope from Earth”—which would be true.
So, is a strontium atom purple? Well, let’s table that. Does a strontium atom look purple when viewed with the unaided naked eye in ordinary terrestrial lighting conditons? No; it cannot be seen with the unaided naked eye. (Right? Or do you say that it can?) Does a strontium atom look purple when subjected to laser light of a certain frequency, etc.? No; it still cannot be seen with the unaided naked eye, even then. Does a picture of a strontium atom which has been subjected to certain light etc., taken with a certain sort of long-exposure camera, etc., look purple? Clearly, yes.
(This part is also confused, but I defer commenting on it, as I would like you to address the other things I’ve said in this comment and prefer to avoid distractions; I merely note it for the record.)
(I’m coming to this rather late, and will entirely understand if Said doesn’t want to resurrect an old discussion; if not, I hope no reader will take the lack of response to indicate that my points were just so compelling that Said had no answer to them.)
I am unconvinced by your argument here (which may just indicate that I haven’t grasped what it is). The following position seems pretty reasonable to me: There are violet photons but not magenta photons. There are orange photons, but because of metamerism you can see something orange without any orange photons being involved. Violet photons are not violet in the same way as a piece of paper covered in violet dye is violet, but it’s reasonable to use the same word for both.
Would you care to make more explicit your reasons for saying that there is no such thing as a violet photon? (You actually said purple, as Charlie had done in the comment you were replying to, but I’m fairly sure your position is not “there are photons of some colours but not of others”. My apologies if I’ve misunderstood.)
Like many things, it would look different in different conditions of illumination. Unlike most things we look at, its spectrum is composed of a few sharp peaks, so the relationship between its illumination and the colour we see (given sufficient “amplification” since of course a single atom can neither emit nor scatter very much light) is a bit unusual. (One can make macroscopic materials with similar properties and I don’t see any particular reason to deny that they have colour.)
This seems like a matter of definitions, and I don’t like your definitions. Whatever difficulties there are about assigning a colour to Neptune are simple a consequence of the fact that it’s a long way away from us. (I think it’s clear that there’s a fact of the matter as to whether Mars is red: it is. If Neptune’s orbit were where Mars’s is, there’d be no difficulty saying that Neptune is blue.) Are you sure you want to say that whether a thing has a definite colour can change merely on account of the distance between it and us? If we sent astronauts to Neptune instead of just probes, would there then be a fact of the matter as to whether Neptune has a colour? If there were an accident and the astronauts died, would Neptune’s colour-having-ness change? If I take an orange, lock it in a vault (illuminated, let’s say, by an incandescent bulb in the vault), and throw away the key, does there stop being a fact of the matter as to whether the orange is orange?
Incidentally: yes, the reporter is wrong about something. A quarter of a nanometre is not 2.5 x 10^-7 metres.
Well, you are free to use the word “color” in such a way that there is no fact of the matter about whether Neptune has a color if you wish. But I think that this directs us into a definitional argument that I don’t feel like having—in fact, almost a perfect analogy to “If a tree falls in a forest and there’s no one to hear it, does it make a sound?”
So yeah, it’s been fun :)
No, this isn’t a definitional argument. Insofar as your view leads you to misunderstand very real facts about human color perception, it is mistaken. Again, consider the questions I asked about “photon color” at the start of the grandparent comment.
This sort of misconception is quite common, especially among mathematically or physically inclined folks who have not studied color theory and the psychophysics of color. It leads, unfortunately, to mistakes in the design and implementation of various systems that have to use or manipulate color in one way or another.
It’s certainly your right to tap out of the conversation. But I hope that you’ll consider what I’ve said (and the same goes for anyone else reading this exchange who feels that Charlie Steiner’s perspective makes sense).