"The Light That Never Warms"

[austinjimm]

I was listening to my old BOC records tonight and a certain lyric got me thinking about magical light (i.e the light spell) v. infravision:

Does the presence of magical light ruin infravision?

If so, why?

Does a light spell produce heat?

[PatW]

I say yes. I don't think of infravision as ruined by the "heat", but rather it's a lot more like night vision - if you've got other light sources around, all those infrared-capturing rods and cones in those poor little dwarven eyes are washed out.

[austinjimm]

That's fine... as long as you're house-ruling it. But my understanding of infravision as per the DMG it that it is dependent on heat, thus the disruption of infravision by torches, etc.

EDIT: DMG, page 59 says that players with infravision "note differences in thermal radiation, hot or cold."

[Benoist]

I was listening to my old BOC records tonight and a certain lyric got me thinking about magical light (i.e the light spell) v. infravision:

Does the presence of magical light ruin infravision?

If so, why?

Does a light spell produce heat?

Yes it does spoil infravision, and no, it's not about heat.

It's about how the eye adapts to the environment, to me. Having infravision capabilities means that your eye gets used to the surrounding darkness in a specific way, able to see heat waves and emanations. If there is no darkness, you are not seeing heat waves, just like if you were in a full day in a cold environment, you wouldn't see heat waves either.

[austinjimm]

Yes it does spoil infravision, and no, it's not about heat.

It's about how the eye adapts to the environment, to me. Having infravision capabilities means that your eye gets used to the surrounding darkness in a specific way, able to see heat waves and emanations. If there is no darkness, you are not seeing heat waves, just like if you were in a full day in a cold environment, you wouldn't see heat waves either.

Again, this is a fine "interpretation" if you are house-ruling. I'm pretty sure I posted this in the BTB thread. From my earlier post:

DMG, page 59 says that players with infravision "note differences in thermal radiation, hot or cold."

EDIT: And to reiterate the thus-far ignored issue: Does a light spell produce heat?

[austinjimm]

This appears to be the answer to my first question, PHB p. 102:

All infravision is spoiled if a light source is shedding illumination...

As to the latter question, "does a light spell produce heat?", any BTB answers to that one?

[Benoist]

OK. First this has nothing whatsoever to do with how characters with infravision perceive things. Which is what the phrase you are quoting from p. 59 refers to specifically. I'm speaking of the conditions under which people are able to see differences in thermal radiations, hot or cold, not whether they see thermal radiations or not when they are using infravision: they do.

Do you see the nuance here?

See PHB p. 102:

All infravision is spoiled if a light source is shedding illumination upon the creature possessing the infrared sight capability. Similarly, great heat will spoil the capability.

So it's not either/or. It's AND. Light sources AND great heat sources spoil Infravision. Ergo, whether a Light spell gives out heat doesn't matter. It's a light source. Ergo, it spoils Infravision.

[T. Foster]

PH p. 102: "All infravision is spoiled if a light source is shedding illumination upon the creature possessing the infrared sight capability. Similarly, great heat will spoil the capability."

The Light spell does not give off heat, only illumination (PH p. 44: "This spell causes excitation of molecules so as to make them brightly luminous"), but nonetheless seems to spoil infravision BTB.

[austinjimm]

...it's not either/or. It's AND. Light sources AND great heat sources spoil Infravision. Ergo, whether a Light spell gives out heat doesn't matter. It's a light source. Ergo, it spoils Infravision.

Ahh-So.

Got it.

[Benoist]

As to the latter question, "does a light spell produce heat?", any BTB answers to that one?

Based on the spell description, PHB p. 44: This spell causes excitation of molecules so as to make them brightly luminous.

The question is whether this excitation of molecules generates heat or not.

Now, from wikipedia:

Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state.

In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). The temperature of a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit Negative temperature).

The lifetime of a system in an excited state is usually short: spontaneous or induced emission of a quantum of energy (such as a photon or a phonon) usually occurs shortly after the system is promoted to the excited state, returning the system to a state with lower energy (a less excited state or the ground state). This return to a lower energy level is often loosely described as decay and is the inverse of excitation.

Long-lived excited states are often called metastable. Long-lived nuclear isomers and singlet oxygen are two examples of this.

Emphasis mine. It seems whether excited molecules will produce heat or not will depend on the nature of said molecules/systems, if I understand correctly.

[austinjimm]

The Light spell does not give off heat, only illumination (PH p. 44: "This spell causes excitation of molecules so as to make them brightly luminous")...

\

Something like this, then:

http://scifun.chem.wisc.edu/homeexpts/Chemilum.html