Milk first or last? The correct method for hot tea. (GONE MATHEMATICAL)

Listen to the hot tea episode of Domestic Science here:

Stefan-Boltzmann Law

The thermometer I used was the Signstek 6802 II, the cheapest dual channel thermometer I could find. But it turns out it is only $16.99 in the USA right now:

Whereas I paid £14.29 in the UK:

If you’re in the market for one, I have a second-hand only-slightly-tea-stained one available.

CORRECTIONS:
- According to comments, it seems no one else in the world puts milk in their tea.
- Several people have pointed out that there was not an equal amount of hot water in each mug which would affect cooling rates (the first of which was HueBearSong, who also seemed to be the most disinterested). Is that enough of a difference to justify me doing it again? Comment below!
- As pointed out by user HYEOL, the teaspoon was cold going in to T2 but hot when going in to T1. Which yes, would make a difference. Turns out science is hard.

Music by Howard Carter
Design by Simon Wright

MATT PARKER: Stand-up Mathematician

[ZexMaxwell]

Just for the sake of consistency. One tea had more water than the other....

[olivier]

That's a Parker experiment, with less water in the cup you expect to be colder...

[Pumpkinhead]

I thought the debate was about whether the milk should go into the cup before or after the water.

[markbenjamin]

One thing he doesn't mention is the value of the Stefan-Boltzmann constant, which has a 10^-8 order. This effectively means that radiation effects aren't at all noticeable until you get to about 300 degrees Celsius. The heat radiated is very tiny until then and most of the heat transfer occurs due to conduction and convection to the ambient air, (which is proportional to the first power, not the fourth)

[douglasoak]

you had significantly different amounts of water in each cup. The warmer cup had MORE water in it so it was less effected by the milk.

[ConstantSorrow]

All I learned from this is Matt misunderstood the question of when to add milk.

[MindYourDecisions]

I really enjoyed watching this experiment. From the title I thought this video was going to be about the Lady tasting tea experiment (Ronald Fisher 1935) which was significant in the history of statistics:

"The lady in question claimed to be able to tell whether the tea or the milk was added first to a cup. Fisher proposed to give her eight cups, four of each variety, in random order. One could then ask what the probability was for her getting the specific number of cups she identified correct, but just by chance."

[dropscents]

And around 3:20 we have another proof that the actual force which holds the universe together is duct tape...

[aeonturnip]

Another example of4th power - Rayleigh scattering (responsible for the sky being blue) - the amount is proportional to the inverse of the wavelength to the fourth power, which is why short wavelength (blue) light scatters more than long wavelength (red) light.

[DanJan]

The Answer: You shouldn't add milk at all!!!

[chasegilley]

Man, what an incredible non-beeping kettle. Wonder how you get one to not beep...

[NChambernator]

Looks like you have a bit more water in one than the other. Nice video though! As a chemist, the water levels really bothered me, especially when the end result was a small difference.

[binimbap]

"Is that enough of a difference to justify me doing it again?" YES. You better do this shit properly all over again, Matt. Even out those water amounts and spoon temperature.

[scarcesense]

You've not made the tea properly!

You make the tea in a pot, then put the milk in a mug and add the hot tea into the milk such that the water doesn't overheat the milk. If the order is reversed, the small amount of milk is scolded by the excessive heat in as it is gradually introduced into a comparatively large amount of hot tea.

Both methods end up at the same temperature (as they are done at the same time, only the order changes), but one curve comes up towards the final temperature, while the other falls. It's all up to whether or not you want your milk burnt.

If using UHT milk you're not going to notice as the milk has already been heat treated, but the difference is noticeable by experienced tea drinkers when using real milk.

If you can't notice the difference, then the issue is your palate.

Source: Douglas Adams

[allie-ontheweb]

I would put milk in last simply because you get a vastly better idea of how much you're actually putting in, and can see exactly what the strength of the tea is.
Since the water hardly affects the strength, it makes more sense to put the milk in last

[HAB]

The initial volume of the water was clearly different. What a Parker square. You never fail to disappoint. If i were you I would re-conduct the experiment with more precise measurements.

[JafarChou]

Is no one going to mention that the water levels are not the same?

[DenisFalqueto]

thank you so much for using Celsius. Almost the whole would is happy. 😅

[kernaghan]

Wouldn't the fact that the cups of tea have slightly different quantities of tea affect the temperature of the tea over time as well as affect how drastically the milk cools off the tea? I see you had the quantity milk consistent for both cups but shouldn't you have done the same for the hot water aswell?

[burgersnchips]

When people say "putting the milk in first" what they mean is putting the milk in BEFORE the water, as in directly onto the teabag. The reason why that's bad is because the tea can't brew properly in a cold solution. You brewed the tea then added the milk so you added it second both times, hence why they taste the same.