Can Wall of Force transfer thermal energy?

Question

Is there any text stating that walls or objects made of force can or cannot conduct thermal energy?

For example: Wizard is pushed off edge of volcano into magma. Let's surmise he is able to cast wall of force or some other means that allow him to be inside a sphere of force.

Sphere hits lava, starts to sink. He's protected from the lava by the force wall, but does the thermal energy from the lava "heat" up the force wall which then heats the air inside and eventually traps him inside a death oven where he cooks inside his own wall of force?

Answer 1

Wall of Force does not transfer thermal energy.

The Player's Handbook describes the spell as:

immune to all damage

Cold and fire are both types of damage, and in your example we can assume that the lava would cause fire damage.

The question, then is "Can Wall of Force allow damage to pass through it if it does not take damage itself?" The answer still is no, and here's why:

There are three types of heat transfer: Conduction (contact between two objects, such as in the spell Heat Metal), Convection (which happens primarily in gases and liquids, of which the Wall of Force is neither), and Radiation (does not require a medium, and consists of electromagnetic waves).

We can rule out Convection and Conduction, since the Player's Handbook describes Force as:

pure magical energy

which more than likely does not behave the same as normal matter. In addition, if Force did act in a similar way, then we have a precedent for an amount of Fire damage that does not pass through a Wall of Force, namely a Fireball spell cast at 9th level. This will do the base 8d6 fire damage, plus an additional 5d6 fire damage for a maximum of 78 fire damage. Given that there is no limit to the number of creatures that can take a turn in a round, we can assume that even with even three spellcasters casting 9th level Fireball spells, the wall (and the creature being protected by the wall) will remain unharmed.

Per the Improvising Damage chart on page 249 of the Dungeon Master's Guide,

18d10 Being submerged in lava, ...

That's a maximum of 180 fire damage per round submerged in lava. With 3 9th-level Fireball spells maxing out at 234 fire damage per round, the Wall of Force has precedent for not allowing extreme temperatures to affect the enclosed creature.

As far as heating the interior by Radiation,

Nothing can physically pass through the wall.

That would include things on the electromagnetic scale, since the waves would physically need to pass through the wall, and light would be an exception (not the rule), since the wall is specified to be invisible.

Answer 2

It is reasonable to assume it is immune to thermal energy.

Per the text in the spell.

Nothing can physically pass through the wall.

Which should logically include thermal energy - or more correctly stated - fire damage. If it had said it is immune to physical damage, I would rule differently, but this does not seem to be referencing a keyword. Especially since the very next sentence states:

It is immune to all damage......

which seems to further back up the idea that any kind of damage can not pass through the wall.

Answer 3

Thermal temperature would pass through, but would not deal damage directly.

As with everything else in DnD 5e, if the spell specifies, it does.

It is immune to all damage

emphasis mine. However, The temperatures involved do not deal damage directly, rather

Some special abilities and environmental hazards, such as starvation and the long-­term effects of freezing or scorching temperatures, can lead to a special condition called exhaustion.

emphasis mine again (SRD Here)

Seems that RAW, thermal conditions WOULD pass through a wall of force. This would be consistent with light passing through the invisible wall. (the counter to (thermal = fire) is (light = radiant)).

On the other hand, I can see it being reasonable that thermal energy be forbidden from passing through the wall. If that is the case, then it would depend on when the wall of force was cast, as any excessive thermal energy would be trapped in the sphere with the caster. This would lead to the same exhaustion inducing conditions as though the heat could transfer into the sphere from the surrounding lava (unless it was cast from a spot at a much lower temperature).

Answer 4

RAI, no. Thermal energy is fire damage, it cannot get through or the spell loses its meaning.

Imagine this: Wall of fire right next to the wall of force, warm side facing the wall of force. Do creatures touching the wall of force take 5d8 damage? Of course not. The spell description doesn't even bother to say it blocks spell effects.

Wall of force grants full cover to those on the other side from direct attacks.

The wall of force is immune to all damage. The fire damage would have to break the barrier to get to the other side.

So all damage from any source is just absorbed/nullified by the wall of force, and nothing happens on the other side.

If you are struggling to cope the wall of force with the physics and common sense, let me give you the missing link:

A wizard did it.