A physical description of photons can only work if A) idealism isn't the case and B) they're not conscious. — RogueAI

Specifically to which (whose) "idealism" are you referring?

pain hurts/feels bad/is painful — RogueAI

I just don't understand what your point is in saying this. Do you think you're describing pain by saying that it's a sensation that hurts? It hurts because that's what pain is. Are you defining pain? Explaining it? Are you saying anything at all?

If you were trying to explain what anger is to an alien, would you consider that a complete description? I think it fails because it doesn't capture the essence about anger, pain, happiness, etc.: emotions are feelings. They are things we experience. — RogueAI

Ok then, how would you explain anger to an alien? How are you going to communicate the "essence" of anger?

And again, this is begging the question. You're implying my explanation is incomplete because feelings are nonphysical subjective things we experience. Assuming so already assumes physicalism is false, so is begging the question.

That would seem to be a problem for physicalists. How on Earth can you convey to someone the experiential nature of pain and anger with just a physical description? — RogueAI

Ah so it’s a problem when a physicalist cannot convey what pain is to someone else, but when an idealist/dualist says “Qualia are private and unknowable” it’s no longer a problem but a feature?

:sad:

A physical description of photons would suffice if physical stuff actually exists. If idealism is true, however, describing photons as physical things that exist independent of mind(s) would be false. A physical description of photons can only work if A) idealism isn't the case and B) they're not conscious. — RogueAI

So if a mind can give a complete description of a photon, then the photon is independent of the mind. But if the mind cannot give a complete description of a photon, then a photon must be dependent on a mind. Something like this?

Is velocity a true physical quantity?

If time is unreal what are colors and sounds, these phenomena being defined in terms of time (Hertz)? 

In a Timeless Universe, how are colors and tones defined?

Mary doesn't have a physical description of red in a timeless universe. Mary's Room Argument fails.

Mary has never felt any severe in pain her whole life. She's lived in a nice comfortable room yet has studied everything there is to know about 'severe pain' other than experiencing it - obviously.

I walk into her room and punch full on in the face shattering her nose and fracturing her cheek bones. She falls to the ground wailing and screaming then leave.

Has she learnt anything new about pain due to my brief visit?

It all depends on what we mean by knowledge.

Clearly, the difference between before seeing red Mary and after seeing red Mary is all qualia.

Qualia are nonpropositional and so can't be known like (say) the proposition "God exists".

No, Mary doesn't learn anything new!