Editing 2989: Physics Lab Thermostat

{{comic
| number    = 2989
| date      = September 23, 2024
| title     = Physics Lab Thermostat
| image     = physics_lab_thermostat_2x.png
| imagesize = 264x296px
| noexpand  = true
| titletext = Hopefully the HVAC people set it to only affect the AIR in the room.
}}

==Explanation==
{{incomplete|Created by a BOLTZMANN BRAIN - Given the calculations mentioned in the comment, it would seem that the thermostat works normally in the way that turning it clockwise will increase the temperature. This should be mentioned and some kind of calculation like the one mentioned in comments section could be added for clarity/reference. Do NOT delete this tag too soon.}}

A thermostat is often used to regulate the operation of heating and/or cooling for a room. This may take the form of a simple dial, graduated by desired temperature values marked Celsius or Fahrenheit, depending upon {{w|Fahrenheit#Usage|location}}. Typically a person is expected to know what sort of temperature they will find comfortable, to have heating/cooling effects kick in as the wall-device detects a temperature more than a certain amount below/above that ideal. The basic design of a physical wall-mounted dial might relate the relative position of the dial against the current state of a {{w|Bimetallic strip#Thermostats|bimetallic coil}}, switching {{w|Bang–bang control|on or off}} the relevant systems once conditions locally drift away from the chosen ideal.

In this comic, the thermostat is installed in a physics lab, with those that work there clearly being expected to be familiar with the {{w|Boltzmann constant}}, a more fundamental method of measuring temperature which relates the average kinetic energy of a particle in a gas with the temperature of that gas. The Boltzmann constant is defined as 1.380649 × 10<sup>-23</sup> J/K (joules per kelvin), a value that's used in the definition of {{w|SI base units}}.

Thus Randall imagines a physics lab having a dial that can alter the constant between 1.418 x 10<sup>-23</sup> J/K and 1.351 x 10<sup>-23</sup> J/K. If the average kinetic energy of gas particles remains constant when moving the dial, then changing the Boltzmann constant would change how this average energy is measured in {{w|kelvin}} (and therefore {{w|Conversion of scales of temperature#Comparison of temperature scales|any other measure}} of temperature), thus "changing the temperature". The equation is E=''k''T where ''k'' is the Boltzmann constant. Notice that if E is the same, lowering ''k'' implies a raised T, so the thermostat 'works' as intended. The effective range of the thermostat, presuming it is set to "room temperature" of 23°C (73°F), runs from 15°C to 29°C (59°F to 85°F), with the dial currently set for about 24°C (75°F).

You can build this "thermostat" in real life and use it to "control the temperature" of the room, even if you just craft it out of two pieces of cardboard. Assume you want a nice and warm room temperature of 300 K (about 27°C or 80°F). Rather than controlling the nature of the airflow into the lab (or convection heaters/coolers around it), or indeed having any effect on anything, it sets the definition of "1 kelvin" to a value between "each degree of freedom of every molecule has on average 1.418 x 10<sup>-23</sup> J" and "each degree of freedom of every molecule has on average 1.351 x 10<sup>-23</sup> J" that would correspond to the current warmth in the room being 300 K. With less energy needed for each kelvin, you have more of them. <!-- perhaps try to give practical 'real-world' values (°C and °F!) to what the dial minimum, maximum and current setting might mean to those not used to sufh things? -->

There have previously been control panels for properties of the universe in [[1620: Christmas Settings]] and [[1763: Catcalling]].

Because the Boltzmann constant is primarily concerned with the nature of temperature within a gas, the title text expresses concern that it might not only be applied to the air (hence the capital letters) in the room. Aside from the possibility that those responsible for the {{w|heating, ventilation, and air conditioning}} (HVAC) of the room could perhaps directly enhance or suppress the temperature in all the solids and liquids within the room, in unknown and not necessarily conducive ways, there may also be a secondary joke in which {{w|high voltage}} forms of {{w|alternating current}} (also referred to as HVAC) are influenced, in the related but distinct use of the measure for '{{w|Boltzmann constant#Thermal voltage|thermal voltage}}'.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[A black circular dial is shown with a white indicator line at the upper right. The label above the dial, enclosed in a rectangular box, says:]
:Local Boltzmann Constant
:[The two extremes of the dial are labeled as follows, the first value on the left and the second value on the right:]
:1.418×10<sup>-23</sup> J/K
:1.351×10<sup>-23</sup> J/K
:[The indicator line is pointing to a position on the dial somewhere around 1.375×10<sup>-23</sup> J/K (between the 12th and 13th large ticks clockwise out of 19 total).]
:[Caption below the panel:]
:Physics Lab Thermostat

{{comic discussion}}

[[Category:Physics]]