What is the Zeroth Law of Thermodynamics?

Why is there a zeroth law of thermodynamics? What use is such a simple-sounding law? And how can it be used to smash glass? Chemical engineer Valeska Ting explains in the first film from our 2016 advent calendar, all about thermodynamics.

The first, second and third laws of thermodynamics get all the glory. They’re the most well known and frequently mentioned. But underpinning them all is a final law so fundamental that, although it was established last, had to be moved to the front of the list: the zeroth law. In the first film of our 2016 advent calendar, chemical engineer Valeska Ting explores the zeroth law of thermodynamics.

The zeroth law is essentially an observation: if two systems are both in thermal equilibrium with a third, they are also in equilibrium with each other. This seemingly simple mantra is essential to our concept of temperature, as Valeska, armed with some very hot glasses, explains.

[prettygreenparrot]

Brilliant to see someone who looks so happy and excited to be talking about science.

[eIicit]

Her energy is amazing. When a teacher is passionate about the subject, it’s nothing short of divine.

[DekuStickGamer]

This woman looked like she was gonna break out laughing any second.

[EdMcF]

If you use an invasive thermometer, you change what you are measuring unless the thermometer is at the same temperature as the thing that you are measuring, so you must be approximating when measuring temperature, until equilibrium is reached.

[rayenochi]

a=b
b=c
then: c=a
.... i can't believe someone had to create a law out of this. -.-*

[dennishudson]

this is a clear, concise explanation of the 4 laws. I will use this as a model for my class and i hope you will produce new presentation..

[Hythloday]

Temperature isn't a 'fundamental' property of matter. It is an emergent phenomena!

[maupn]

@1:07 in the computer world this is similar to Transitive trust. If A trusts B and A trusts C then B will have no problem trusting C due to the trust they both share with A.

[Hythloday]

Leonard Susskind has coined the phrase for conservation of information as the 'minus 1'th law' as the most fundamental principle in theoretical physics / thermodynamics - it's a great concept !

[polyv]

those glasses look very refreshing, remember to drink water folks

[jenko]

Great video, but in my opinion the best way to explain this subject is in terms of molecular vibration and the Kelvin scale. To me it makes it easy to visualize . Shake slow, cold, shake fast, hot.

[EddieVBlueIsland]

You missed the subtle point of the 0th law.  Temperature is a state function based on the nature of heat itself and temperature is its independent measure regardless of it source. So for objects A, B and C (not necessarily identical)  if A is heated by microwaves to temperature T, B heated by chemical reaction to temperature T, and C heated by the sun to temperature T  - the heat in A, B and C is the same in the sense of summed atomic motion  (but not the total amount of heat for different objects)  independent of the heat source. Subtle but necessary for the other laws to work.

[jyotismitadoley]

I found a good source to master my basics!!! Thank u😎😎

[CrazyIvanTR]

It just seems like the "0th law" is a given. I'm thinking that must have been why they didn't even bother to write it down in the first place. Well, we wouldn't know what they were thinking unless they documented it. So, all I have is speculation.

[godbluffvdgg]

Awesome presentation! You're a splendid teacher! Thanks so much!

[colesrk]

Can someone help me understand why a third system is needed to get a temperature measurement? Why is A=B; A=C; therefore C=B required for measurements and scales? Could we not get measurements and scales just from A=B; therefore B=A? What makes the third system required?

[RobertShaverOfAustin]

Do the laws of thermodynamics apply to all forms of energy or only energy in the form of heat?
For example, if I raise a one pound weight up one foot in the Earth's gravitational field, it now has one foot-pound more of potential energy than it did before I raised it. Did it get warmer or colder or stay the same temperature? I'm confused as to how thermodynamic principals apply in this case.

[DaytakTV]

Thermodynamics is a fascinating subject!

[Fransamsterdam]

How can you measure the temperature of a system without interfering/disturbing the system, which means changing the temperature?

[AttilaAsztalos]

An overview of why the other laws follow from this one would have been more useful. Also some thoughts on why this isn't self-evident and needs expressed as a "law".