Milk first or last? The correct method for hot tea. (GONE MATHEMATICAL)
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- Опубліковано 23 вер 2024
- Listen to the hot tea episode of Domestic Science here:
www.bbc.co.uk/p...
Full data footage is over here on my second channel: • Milk first or last? Th...
Stefan-Boltzmann Law
hyperphysics.ph...
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:
www.amazon.com...
Whereas I paid £14.29 in the UK:
www.amazon.co....
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
Website: standupmaths.com/
Maths book: makeanddo4D.com/
Nerdy maths toys: mathsgear.co.uk/
That's a Parker experiment, with less water in the cup you expect to be colder...
The Parker 4th power :D
So like a Parker square result, squared :)
+
+umchoyka "I should have said may the Forth be with you!"
+
Just for the sake of consistency. One tea had more water than the other....
Grrr....That drove me nuts when he did that. He had the milk in graduated cylinders, but started with different amounts of tea.
(I'm a bit rusty on my Thermodynamics) but I don't think it would make that large of a difference since the power radiated is proportional to the surface area, and since the glass is insulating the tea on the sides and bottom, what matters is the area of the surface, which would only be slightly larger for the one with more water (due to the shape of the glass).
@@looney1023 That sounds logical when you talk about losing heat over time, but when you add the same amount of (cold) milk to a smaller amount of (hot) tea, wouldn't the mixture be a lower temperature? If you add the same amount of milk to a bucket of tea, the temperature would be higher wouldn't it?
@@Exevium That would also be a factor, sure. I would guess the difference in T due to volume would also be fairly insignificant. Ideal gas law says it'd be a linear correlation with a small change in V. Obviously the world isn't ideal, but for a low fidelity experiment, I'm still inclined to write off these errors as insignificant
I wouldnt be mad if it wasnt for the graduated cylinders
The Answer: You shouldn't add milk at all!!!
people do that?! O_O
Yes?
+slendy9600 yeah. tea gets undrinkable when you add milk and it gets cold
Yup. Black tea is a thing. No idea why people would do such a thing
It depends on the tea ofc...
I thought the debate was about whether the milk should go into the cup before or after the water.
Pumpkinhead77 same...
Same.
me too
he explained that one in the beginning. if your cup cracks easily, add milk first for protection against hot temperatures. if not, then there's no reason to pour milk in before the water.
@@gadnihasj Admittedly the 'tradition' of adding milk before water was originally to prevent expensive delicate porcelain dmg, now pretty much irrelevant, but it would still be a valid test.
I'd let the tea brew a bit longer than 15=30s to get a significant taste tho..
More important to my mind is that adding milk after water (& brew time) allows you to judge easily how milky you want the tea to be
All I learned from this is Matt misunderstood the question of when to add milk.
This video confirms that you are, in fact, British.
he's actually not
But he lives in the UK :)
Not a single queue. Confirmed not British.
So, you're saying Britain is full of people who aren't real Brits?? According to the UK Tea & Infusions Association (it's real, you can google it), 98% of tea here is taken with milk.
First of all, It's "A real Brit". Secondly, almost all of us add milk.
Is no one going to mention that the water levels are not the same?
I completely second that! It was very obvious.
It was screaming at me the whole time.
I was going to mention it, but I'm not certain that it accounts for the entire temperature difference.
That really bugged me as well - he measured the milk, but not the water!
For completeness sake. The water levels were not the same. Also, air temp could have been different in the two spots. I think he checked for that by showing the diff was 0 or .1 C though.
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.
Douglas Oak *affected
Loved the video!
+Cody'sLab Thanks! I might need to do a more precise version though.
You like Matt Parker's videos too? Man, that's awesome.
+standupmaths Yes Matt, you should :-). I might be wrong but it looks like the temperature sensors are thermocouples. If they are, are they water tight? If not you are measuring the surface temperature. Do we think the main energy loss is due to radiation? Just asking :-).
i love you
Cody!
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)
Yeah. The equation reduces to Newton's law of cooling
I also thought that Newton's law of cooling would be a much better model for this scenario
tea in a mug cools primarily by evaporation
look it's simple:
-if you're pouring the tea from a pot, add the milk first lest you be labeled as a working class buffoon.
-if you're making tea in the cup with a bag, add the milk after removing the bag otherwise you will be executed within three working days.
note: you may only add sugar to the tea if you have experienced a traumatic event of some description (such as falling off your bike) and need the reassurance that only sugary tea can provide.
finally, rules i can live by.
XD
I would aslo add it is accepted that people with a physical job are allowed sugar in their tea.
They're allowed some tea with their sugar...
4 parts sugar, 1 part tea
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.
I agree. He could have taken a sharpie and marked a line on roughly the same level which would have helped consistency
Are you saying that the temperature of a small amount of water is different than a large amount? Imagine a big ice cube and a small ice cube melting in the sun- The big looses heat slower than the big one, right? Actually, the heat loss is constant; the smaller ice cube has a lot less surface area. The loss is still X at a rate of Y per Time. So it is with the tea. The thermometer do-hicky was in hot water, so all of it's surface area was covered. It still lost heat at a rate of X at a rate of Y per Time, as illustrated by the initial test (when he removed the tea bags). As heat radiated out and the molecules slowed, the surface area (to the air) wouldn't have mattered THAT Much since the cups were the same size, and the cups were glass, and did not reflect U.V. light (it wasn't colored glass) so the test is fairly consistent. Heat loss was still consistent until he added the milk and changed the rate of molecular vibration. It's like a room with flubber-bouncy balls zipping about, and then you add a marshmallow man suddenly in the mix. The milky marshmallow man will suddenly slow the rate at which the flubber bounces substantially upon insertion. Coincidentally, the poor marshmallow man will be shredded to bits and the bits would speed up to the speed of the flubber until it all just evens out. This is what the test is showing, and it does it o.k. in my opinion. Am I being ignorant? What do you all think?
It's less about losing heat to the ambient temperature (which may or may not be independent of total fluid volume), and more about the addition of milk. In the smaller cup, the (colder) milk is a larger percentage of the final overall amount of fluid. This will most definitely skew the results towards the "less tea water" cup being colder, since it has a higher concentration of milk.
EighteenCharacters
That's not what I was saying.
This was exactly what I was thinking the whole time. Come on Matt, you can do better than that.
When you said milk first, I thought you meant milk before water.
I wonder if that shows that I am not a tea drinker?
He just did the experiment wrong.
+toddbod94 or rather titled it wrong I guess.
Milk before tea is an accepted procedure, amongst the degenerate community
in India they make it only with milk (which to be fair does contain alot of water)
I honestly expected this too.
And around 3:20 we have another proof that the actual force which holds the universe together is duct tape...
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
as someone who likes tea with no milk, and probably couldn't tell the difference if he did, i approve of this comment =)
Man, what an incredible non-beeping kettle. Wonder how you get one to not beep...
I wonder if he's voided the warranty. I think you don't really own something until you do.
I don't think I've ever had a kettle that beeps.
+devlin Lynden mine certainly doesn't
Void warranty and remove speaker
+devlin Lynden I thought the joke was clear.
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
Also, I feel that temperature really doesn't matter since they're both too hot to comfortably drink immediately. I'm guessing the difference having the hotter one has is so tiny it doesn't even give you a minute linger of heat.
agreed, this is the best argument so far.
I have the same reason for putting the milk in first....lol
Especially if you are lazy and making tea for one in the cup with bag in.
Add milk, wait, brew stir, and remove tea bag at the appropriate colour band.
Black tea requires a temperature above 80 degrees C to not be bitter. Do not add the Milk until after the the bag is removed!
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.
Yeah, but if you make the tea in a pot you should add the milk to the cup before adding the tea. This is common knowledge, or so I though.
+toddbod94 That again is adding the milk after it's brewed hence no difference in taste. It's about boiling water hitting the teabag rather than somewhat cooler water hitting the teabag.
+burgersnchips wrong.
There's a difference in taste if you add milk to brewed tea vs add brewed tea to milk. Adding the milk to the brewed tea spoils the milk and you get a bitter taste, adding brewed tea to the milk gives a better taste.
In your scenario you are supposed to brew tea in a teapot
Sometimes I'll make a pot of coffee, pour myself a cup but leave out the milk until I'm done making eggs and toast. This video showed me the error of my ways. Not quite the "milk first" tea "debate," but at least the video addressed some problem appropriately!
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.
"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.
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."
Fisher came up with a procedure (Fisher's exact test) that tested whether she could tell the difference. The lady was able to tell the difference at a 1.4% significance level! More about this on Wikipedia: en.wikipedia.org/wiki/Lady_tasting_tea
dang aint no way mr. fresh walkytalker
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.
It's acting as a noun...
Agree, couldn't watch the rest if he's not being careful with the variables
the "you never fail to dissapoint" was a little harsh dude yeesh
+Frank Meoño It's for damatic effects
An he needs to use separate spoons for stirring. It gets warm after stirring the first tea.
Aren't you suppose to have same mass of water?
And also cilindric caps for constant speed of vaporisation?
And also, instead of milk you should use lemon.
They both will have the same temperature but different energies so it does not make such a difference. Other factors do make a difference but it is veery insignificant.
he used milk because that's how most Brits usually drink their tea.
DON'T RUIN THE TEA BY PUTTING THINGS IN IT!
+Crazmuss - spot on, mate! +Neandercatz - If you add 10ml of cold milk to 1L of hot water in experiment#1 and add 10ml of cold milk to 10ml of hot water in experiment #2, the 2nd experiment shall have a lower temperature, yes? I'm not saying that Standupmaths' theory is not correct; just that the experiment is flawed.
If you take the time to measure the milk but not the water, it defeats the purpose.
5:02 When you notice Matt fills the cups with different amounts of hot water...
This assumes that you want your tea as hot as possible. In fact, drinking very hot drinks scalds the oesophagus, and should be avoided. Personally, I tend to wait around ten minutes before I drink mine anyway, so the issue of when to add the milk is moot, as I just wait until it's ready. Actually, I make tea in a mug with an infuser, so I literally can't add the milk first, as it would get milk all over the tea leaves as they were infusing-a thought that would make any Englishman recoil in horror.
Right! Be kind to your oesophagus! (Whatever it is.)
+Christian Geiselmann that is actually the (sometimes only) accepted spelling in England and some other English speaking countries
+KWG Fine. But did I dispute its spelling?
+Christian Geiselmann Perhaps you did not, but if I may dispute your grammar, "it" in "(Whatever it is)" does not have a clear antecedent, and I realize now that "it" refers to anything one consumes, but with the way it is worded, it can interpreted at "Whatever an 'oesophagus' is."
+KWG Thank you pinpointing my linguistic shortcomings. (I mean this seriously.) Indeed
I did intend to refer to the oesophagus (the word, not to the thing), not to anything that could be consumed by (or with the help of) an oesophagus. Whatever this is. (Yey, yes, you are right, I could eventually simply look it up. I was just amused by the word which, after years of reading English literature, I met first in your post. This is no criticism. We all should use more words that otherwise are under-used.)
Well I'm sorry for you power 4 Matt, but I think in this situation, thermal radiation is very small compared to thermal conduction, so heat transfer should be proportional to the temperature of the cup minus the temperature of the air (plus a small negligible term in T^4)
so you're saying...
Δt = t_(cup)-t_(air) + O(t⁴)
I think the cup will reach equilibrium pretty quickly, then the hotter cup still radiates/convects more rapidly. I doubt much conduction is happening to the table.
In Matt's experiment I would chalk the result up to differing thermal mass since each cup had quite different amounts of water but similar surface area. In principle though I think he is correct. Both systems start with the same thermal energy, the one with the higher delta T loses more if it, so the final temperature is cooler.
Now what if the add first cup got cold milk, but the add later cup got milk that was left out while the tea cooled?
I would be curious to see a more scientific experiment on this.
Small negligible term in T^4?
Let's say that T(1) = 78 and T(2) = 77, being a 1 degree in difference.
In Kelvin, that's approximately 351k and 350k.
Now do the maths:
351^4-350^4 = 172236401.
My first guess is that this is not negligible, but I may have to look more into it.
Cameron Pearce The constant of proportionality needs to be accounted for, and that may be sufficient to make the term negligible.
Jack Lam Right, got ya.
What sort of monster adds milk to their tea to begin with? Might as well divide by zero while you're at it.
Try drinking English Breakfast tea without milk.
brewed tea produced tannin, a substance with astringent flavour that many people usually don't really enjoy. the fat in the milk actually mellowed the astringency of the tea, and add creaminess to the drink.
I have been drinking English Breakfast tea without milk for years. I hate having anything added to my tea.
Those guys in europe that still have a culture.
Granted - in a petri dish
thank you so much for using Celsius. Almost the whole would is happy. 😅
He's in the UK so there's no confusion. It's always Celcius over there. The only country that has to double check is Canada because we officially use Celcius but we interact so much with the US that we can never be sure what any number we see is (same with metric)
You officially use Celsius? Then why do all my friends in Toronto and BC have thermostats that only show Fahrenheit? :)
***** I live in Brazil. We use Celsius here.
Denis Falqueto sorry, my comment was directed at Justin White :)
I have several friends in BC and in Toronto, and they work mainly in F, but can do F or C interchangeably.
***** Yes, Canada is officially on Celsius and our weather reports are in Celsius. People in any kind of trade use the US system because more of our trades are grandfathered from US industry and we trade with the US (two different versions of the word 'trade' in the same sentence - sorry!)
For example, I used to work in Photofinishing. The standard photo size is 4x6 inches. So even though Canada is 'officially' metric - in practice we use 'Imperial' (USian) more.
All thermostats sold in Canada have both Fahrenheit and Celcius on them. Same with thermometers and stoves and pretty much everything else. If your friends have thermostats without Celcius on them then they got them in the US.
I used to live in BC, I now live in Alberta. I have no idea what they do in Ontario but I imagine that the rules there are the same (both F and C)
Trick question: The correct method is no milk.
I tried that earlier today cause I ran out of milk, it was truly horrible.
But I sense one could get accustomed to it over time, but whats the point?
But tea with milk just tastes like warm milk but worse.
Colin Java, that's probably because you're doing it wrong. Adding milk tends to mask faulty tea brewing methods.
How am I doing it wrong? I like tea with milk in.
Why don't you just eat tea leaves then, surely the water ruins it. Tea leaves on their own would be purer.
If your tea tastes horrible without milk that means you're doing it wrong, regardless of your adding milk to it or whether you like tea with milk. The same goes for other beverages such as coffee.
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?
It would be nice if that kettle had some way to tell you when its hot. ;)
That was a very filigrane joke.
You haven't even started the experiment with the same amount of hot water in each mug...Which means of course T2 is colder, with less water. Which means T1-T2 is of course more likely to be a positive number.
Yes, you need to redo this. For science!
Nice one. But, as our engineering students learn the T^4 difference between the liquid and the environment is usually not the important thing here but rather the T^1 difference. Heat transfer through convection (liquid surface and mug to air), conduction (mug to table) and evaporation are all dependent on T^1 difference and typically more important for the cooling rate. In fact, the evaporation is really important which is why you get a lid on your cup in many places. (And the temperature difference between liquid and air is not as straight forward as one first may think, see wet bulb temperature…)
the tea cups didn't even have the same volume? and you call yourself a proper scientist???
Michael Hood kinda makes using the graduated cylinders of milk useless...
Michael Hood He has that written in corrections. Check the description.
He's a mathmatiction
Michael Hood He's a Parker scientist (Sorry for the parker square joke)
I'm sorry, but this experiment has one SERIOUS flaw. You put much less hot water in cup 2. So the ratio of hot water to cold milk is lower in cup 1!
was milk already at room temp for both or did the second graduated cylinder have 5 minutes to warm up further? Also pretty substantial difference in the amount of water as mentioned below
I thought you were going to do that horrible thing that the fast food joints do of pouring water over a milk-soaked teabag so you get points for that. (I have made them pour it out and start again at McDs.) The temperature that way is to low for a decent brew. You lose points on the different volumes of water in each cup which affected the average temperature when the milk was added. Ideal brewing temperature is not boiling but somewhere in the 90s, as with coffee. Your cups sucked heat out, so in both cups the water was in the 80s. Next time use a warmed teapot for best brew, preferably with leaves rather than bags. 30 seconds brewing is all that is required. Greater time darkens the tea but does not improve flavour. What I do appreciate is your reference to the quality of the cups. My theory is that the upper classes added milk to tea because their higher quality china handles the heat shock but lower classes add tea to milk because the shock would craze their lesser quality cups.
You must really like tea.
You're overthinking it, if you add the milk first there is no need to stir it.
They often use unusually hot water (very close to boiling) in fast food restaurants - this has a habit of scalding the milk if done last. Also, as a result your beverage will normally brew well enough regardless of milk order.
+Dixonary when making most black teas, the water should actually be at a rolling boil
Of course it is correct that the water should be at a rolling boil (and it is obvious that unless under pressure it will be no hotter than that), but as you will see from the video, heat is lost into the body of the drinking vessel (or teapot). It is traditional to warm the pot to mitigate such cooling, but to bring it also to 100C would make it untouchable, and thus the ideal brewing temperature in the 90s is achieved. In fairness to the fast food joints, as they serve in polystyrene a greater temperature is achieved than in a pot or mug, even with milk in the mix. In my tale above I was buying tea for my wife: I personally refuse to drink either tea or coffee from cardboard or polystyrene, and prefer not to drink milky tea from glass as it looks disgusting.
"And I'll just..."
"..."
"Okay, that is substantially more on fire than I expected"
"That is substantially more on fire than I expected"
Why are you going with Stefan-Boltzmann? Newton's law of cooling is dominant here. Much more heat is lost through convection than radiation.
I was thinking the same!!
Stefan Boltzmann would have been relevant if velocities were considered!
Why would you use the Stefan-Boltzmann equation instead of Newton's law of cooling?
Newton was a dog
an over-rated one at that
Yeah doesn't the Stefan-Boltzmann law only apply to blackbody radiation anyway like that of stars?
Evaporation should be the most significant factor in tea cooling, I think. Crossing the threshold from liquid to gas in water takes an immense amount of energy away from the cups.
For dropping the tea bag into the cup you may even use Newton's law of gravity.
flawed result, one has more hot liquid to start with,
Probably someone has already commented this, but there are more reasons to put the milk in first than were mentioned in the video.
1) You can accurately gauge how much milk you have put in as a proportion to the cup size, when you can see the milk sitting in the bottom of the cup. Most of us do not have granulated cylinders to pour out of in most tea-drinking scenarios.
2) By putting the milk in first, with the sugar, the sugar can begin to dissolve into the milk while you're waiting for the tea to be ready to pour, so that once you do so, you get a better solution with less stirring. (And, it should be noted, more stirring causes colder tea.)
An example of fourth power relationship in the real world is the amount of damage that a truck does to the road. Basically, the relative amount of wear (or damage) a truck does to a road is proportional to a fourth power of the weight. For example, a 2 ton axel of a truck does 16 times the wear to a road as a 1 ton axel of a truck. Search for "Generalized Fourth Power Law" or "Equivalent Single Axle Load".
What about the fact you put much less hot water on T2???
Cold spoon in Cup one, Hot spoon in Cup two
fail
not same tea volumes anyway
I'm mostly concerned about the milk in the graduated cylinders getting unrealistically warm, what did you do to compensate for that?
actually I just realized cold milk might be an american thing? Are brits just okay with warm milk?
Warm milk spoils..
Technically, since there was a significant difference in the amount of water in each mug, the cooling effect of the milk would have been greater for the mug with less water in it.
It is not because of drinking temperature, it is because of brewing temperature
I use an insulated cup so the minute temperature difference at the end of production is fairly irrelevant
I put the milk in last for several reasons.
I like strong tea so leave it brewing for a while.
so most importantly
1' so the water is as hot as possible for the brewing, brewing in luke warm water produces a weak tea.
also
2; so I can see if I have left the teabag brewing.
3; so i can gauge how much milk I want to put in based on the strength of the tea and how long it has be brewing
4; I don't like the look of teabags floating in milky water or fishing out milky teabags.
finally
to maximize the amount of tea to drink. the milk fills the space left by removing the bag, space that is not available if the milk is put in at the same time as the bag.
I don't even like tea
Up next on standupmaths: Coffee, Conic Sections, and Cats.
same
Frist of all how dare yo u
Ice tea is one of my favourite drinks, but regular tea is gross.
liquidminds I don't understand the sugar thing.
what about pouring water first, then milk, then teabag? would that change anything because it's the way i make my tea
I do milk, tea and lastly water.
you should put the hot water on the teabag, without the milk. It helps the tea brew better.
I guess it doesn't matter as long as you can't tell the difference. I tried to replicate your experiment in various ways and the tea always tastes the same in regards to temperature and flavour.
You'd get to see a disgusting mixture of milk and water before you drink your tea...
then you get to be a monster! :D (kidding, kidding)
The correct way is:
NO MILK! I never got why British people can't have tea without milk. It's such an odd combination.
This, unless it's chai in which case you make it in the milk on the stove. :)
I'm largely convinced many British people put coffee in their tea for the same reason a lot of Americans put it in their coffee - because they drink over-steeped, lower quality tea at home - most people aren't savvy to the right temps or times (you can't trust the average brit with green tea in particular cause they think all tea must be boiling hot, which with anything more sensitive than a heavy roasted black tea can scald the leaves and add a astringent flavor), and buy whatever generic/cheap (Lipton.. shudder) tea because it's cheap. They put milk in to cut the flavor and thus it just becomes a habit and familiar. Same for some american families drinking nothing but Foldgers coffee with milk and sugar (though there is more of a trend to drink it black here for macho reasons ;)).
It's the same reason why people put milk into coffee. And I think, it was also something what many Europeans did in the past because according to my mother, the Poles put once milk into tea too.
The real question then... should you not add the milk before or not add it after?
Milk usually goes with black or green tea. I think it is tasty.
@devoltar Go home hipster snob.
If you were sufficiently bored enough to do an experiment which eliminated as many variables as possible, you'd probably need two kettles, each mug marked with a water fill level, two identical teaspoons and so on. The cooling rate will also depend on the shape (mainly with respect to the area of tea exposed to air) and size of the mug, as well as the material it's made from (different materials have different insulating properties).
The latter could be an interesting experiment in its own right - pour an equal amount of boiling water into various mugs (glass, 'ordinary' china, fine bone china, plastic, maybe even a vacuum flask) and measure the rate of heat loss...
The differing water volumes bothered me to no end. This video deserves a redo!
Different volumes of water in the tea totally messes it up.
Also, what if the milk is chilled?
I second that. Seriously, Parker, why would you go to the "measure" of using graduated cylinders to get equal volumes of milk in each tea if you are not going to be sure you have equal volumes of water in each tea? It doesn't matter much if the milk you added was chilled or not, but there is no evidence in the video that they were equal temp with each other. And, . . . all the other questions you left completely unanswered.
My only hope for this video is that you possibly plan to make another, explaining why none of these possible confounding factors matter, or that this video was completely bunk and here is another similar experiment conducted with very much fewer variables.
Or, maybe this video is not intended for students of the sciences (such as myself, and probably James Moran).
Parker, maybe the folks over at Periodic Videos can clear up all the details of this for us?
If chilled the difference will be slightly larger.
Really radiation equations for things at 100 degrees C. Radiation is not really relevant until things get really warm i mean around like 500 hundred C the heat loss trough convection evaporation and conduction are way bigger at those kind of temperatures especially while dealing with a liquid.
You fool! You put milk in first into the mug/cup IF you have pre brewed in a teapot. If you decide to bypass the tea pot, it lowers the temp BUT also can block the holes of the bag. Philistine
The key with making tea with milk first is to let the milk warm to room temperature, and let the tea bag diffuse into the milk (it does so siginificantly better in warmer milk) and leave it for an hour or two (best to prepare while making your previous cup). You'll find the tea far more creamy, YUM!
In all practical application, the rate of heat loss is proportional to the T(body) - T(surrounding)....
Three cheers for Newton.
why measure the milk but not the water?
There is less hot water in the cup to your right ! This annoyed me too much. Make them even !!!
+ I totally agree with you qateralneda.
Any civilised person knows that you put the milk in the cup before the tea because you use a teapot and putting the milk in first results in a better flavour.
Exactly.
apparently blind testing proofs no taste differece. only where is the propper quotatian of the study?
"Any civilised person" never adds milk to tea.
You way overstated the T^4 thing. If you look up some estimates for evaporative cooling and convection they should be considerably larger. The temperature difference is still the driving force, but the power is less than 4, and variable depending on regime.
Not hating, I love this stuff. I'm just a nerd!
I know it's an older video, but it does make a difference...
Due to the different consistency of milk vs water, the proteins in milk make the overall thickness of the liquid slightly thicker, this in turn means they don't penetrate and diffuse the tealeaves as well or as fast...
putting milk in first, and leaving tea bags in for the exact same amount of time, means the one with milk first is weaker.... yes, you can get them to taste the same, leave the teabag in for a little longer if milk first for same strength...
Temperature is just a by-product!
~
Edit:
Also, you did it wrong, Milk before water if you're doing milk first....
Teabag, Milk, Water... wait 3 mins.. OR
Teabag, Water, wait 3 mins... Milk...
That is the difference between 'milk first' and not!
When you added the milk relates to the days in which Tea was made in a teapot. When pouring tea the milk was added first so that the swirling of the tea mixed the milk in the cup without the need for stirring.
This experiment is wrong at so many levels.... ;o
1. There aren't equal amounts of water in both cups.
2. You didn't pour water to both cups at the same time, so it started cooling earlier in the first cup.
3. You didn't make sure that the temperatures of both milks are the same. What if one of them was hotter than the other?
4. There's no account of how much heat goes out of the equation under the radar when you pull out some of it with the tea bags or use the spoon.
5. There's no account on how fast the milk cools down when waiting in that cylinder.
Not to mention that if the whole argument was about the tea having a better taste, it is obvious that the longer it stays hot, the longer it extracts the aroma from the tea leaves. As soon as you pour milk into the cup, the temperature drops down and it is not enough to extract aroma from the leaves. It's similar to how it would be if you poured in lukewarm water to the cup: the tea would be very weak and never get better, and it would taste awfully.
If you want this experiment to mean anything, next time to use calorimeters and make sure that all the external conditions are the same for both cups. Otherwise you can draw _any_ conclusion from your experiment and it will be meaningless anyway.
Nevertheless, I was hoping that this video would be about noncommutative operators, not physics of cooling, but I guess the "MATH" part misled me :q
Those are genuine errors in the experiment but that does not mean the result is wrong. The factors you mention volumes/ times/milk temp would have little to no effect on the FINAL RESULT. He didn't add the milk before pulling the tea bags so your argument about extraction makes no sense. A calorimeter would only be useful if he was gonna make calculations this is clearly a qualitative experiment he is not recording the change in temp over time and comparing with theory he is just testing if in fact hotter bodies cool faster, sure you could argue there are other factors at play but those factors would not change the conclusion.
In my opinion, the volume might have been one of the larger factors. Also, that equation only describes radiative cooling, not evaporative nor conductive, which I believe are massively greater (compare the heat by the side of the cup without touching to heat of steam above the cup, and heat of surface the cup is standing on)
Sci Twi if your experiment is so sensitive of tiny changes, then there is no meaning to do it in real life, bring a measuring cylinder everytime you want to drink tea then
Teh Yong Lip That was my point exactly. There are too many external influences in this experiment which disturb it with their "tiny changes" that the observations are useless and drawing any conclusions out of them is highly misleading and mistaken. In a proper experiment, such influences have to be eliminated and the things we want to be observed have to be amplified so that the outcomes would be conclusive. In this experiment above, they aren't.
The question should be: WHY ON EARTH BRITISH ADD MILK TO TEA IN FIRST PLACE?!
I've never seen someone put milk on the tea, (i'm from Brazil). Now i wanna try it. What is the best ratio of milk to tea? what are the best flavors to combine?
haven't you ever seen looney tunes ? bugs bunny does it.
haven't you ever seen looney tunes ? bugs bunny does it.
black tea from india or sri lanka and whole milk!! no sugar. 💓💓💓 it's heaven!
It's tradional to put a small splash of milk in, but I much prefer a cup 33% milk
2 cups water 1 cup milk for the traditional Indian way. But if you want a less milkey way(if you aren't used to it) try 3 cups water 1 cup milk. Also, for better taste, put the tea leaves in with the water while boiling, add two juliennes of ginger, a pinch or pepper and a sprig of lemongrass. This gives the tea a nice soothing smell and is good for your throat too.
Well Matt, I estimated that each cup of tea would have a maximum capacity of 450 ml (considering the difference between the relative size of the cup before and after milk).
While the left cup started out with approximately 195 ml of tea in it (measured after you took the tea bag off), the right one had about 240 ml.
As you well know, according to Newton's laws of thermodynamics (in this case the law of cooling) , a bigger object with the same density as another will cool down slower (dT/dt ∝ 1/r , dT/dt : cooling rate, r : radius ). This means that the cooling rate of a given object should be inversely proportional to its radius . We can now imagine the tea being "transported" into a sphere.
If the cup has 450 ml of volume, that means the cup has a volume of 4.5 x 10^-4 m^3(1ml = 1.0 x 10^-6 m^3). Thus, the radius of the sphere of tea is about 0.047538 m (V= 4/3pi . r^3 r = sqrt[3]{ V/ 4/3 Pi})
So, now we have 2 possible spheres :
S1 : 195 ml(1.95 x 10^-4 m^3 | r = 0.0359734 m)
S2 : 240ml (2.4 x 10^-4 m^3 | r = 0.0385515 m)
If dT/dt ∝ 1/r, then dT/dt (S1)
If you have a beam resting on two supports, and the beam is of length L, made of a material with Young's modulus E, a cross section of second moment of area of I and with a load pressing down of w force/unit length, then the mid-span deflection is 5/384*w*L^4/E/I. For a bonus fourth power, the units of I are length^4.
great but… who the hell is putting milk into tea? :D
Jakub Klawiter British....
Jakub Klawiter I'm guessing you're American...
Only the entire united Kingdom. You'll also be surprise to learn that we drink it hot, and many people drink it unsweetened
People from around the world drink tea hot and without sugar, but drinking it with milk is probably almost exclusive to UK indeed.
In Germany we also very often drink tea with milk.
Who puts milk into tea in the first place o_O ?
Apparently, him.
Probably a few billion people...
I've never heard of the milk argument having anything to do with heat. I've read that putting the milk and sugar first lets the sugar start dissolving beforehand. But I put them in last, because I won't know how much of either I'll need until I finish making the tea! I can't very well predict the exact amount that will taste good before I make the darn tea!
Thanks for the experiment with the bagged tead, but as an enormous tea afficianado I do need to give you some caveats.
While this information will deffinetly work for tea bags. Bagged tea is rather processed and has a wider optimum range for steaping than if you would use leaf tea. Speaking of leaf tea, these teas generally need a rather specific range of temperatures and much shorter steaping time than an 'ordinary' bag and as such need constant temperature measuring and the least amount of interference from the milk while steeping. In other words when making a nice cup of quality tea, more than hot tea matters.
But I know I am just one of a few people left who care as much as this about tea so for general purposses I agree and thank you for fueling part of my obsession.
one more example of 4th power in real world:
the flow rate of a fluid at a constant pressure is in a direct relation with the 4th power of the radius.
I have two problems with this experiment. The first, being that the two cups did not have equal amounts of hot water, the cup on the left (your right) had slightly less water. Secondly, assuming the milk isn't already room temperature, the second portion of milk would have warmed during those 5 minutes.
The heating element in the kettle is at the bottom, and you didn't stir the hot water so the first pour was actually hotter than the second as the reading suggested. The water levels were slightly different. At this point stirring them at a different time/rate could grossly effect the absorption of heat into the glass, because one has slightly more exposure to the glass. Adding the milk increases the surface area exposed to the glass, so even more absorption occurs. The handle acts as a heat sink so closer exposure to it.... Oh never mind, you should put the hot water in first to melt the sugar, because un-sweetend tea is blegh.
Yes, you should correct the water volume problem and do this again. Because science is fun!
Hi Matt,
This does remind me about a discussion we had at the National Dutch Research Centre: Is it better to add powder milk to your coffee or cooled milk. The goal here is also to keep the coffee as hot as possible.
The milk is stored in the refrigerator at 4C. The powder at room temperature (about 19C). The liquid is colder so it will have a greater cooling effect that the powder has to be dissolved which also cost energy. We could not find a theoretical solution. Are you able to give one?
Because we could not find the answer theoretical we conducted an experiment. About the same you did in the video. As I recall correctly, powder milk won. But the next day, team cooled milk had collected more thermometers so now all our beverages where tested.
Result: No correlation between the kind of milk and the temperature. The conclusion: The thermometers where not accurate enough to measure a difference. So as an engineer I'm not convinced with your one of lucky experiment that just happened to confirm your theory. Please repeat your experiment and determine how accurate you can measure the temperature difference.
The Stefan Boltzmann equation used is only for heat radiated in the form of electromagnetic radiation. For your cup of tea this very likely will not be the dominant source of heat loss, the tea heating it's surroundings will likely vastly outweigh this, therefore the 4th power of temperature is trivial in this case. If you don't believe me consider hot soup in a thermos. The soup is constantly radiating in the electromagnetic spectrum but is still able to stay hot for a very long time as the major source of heat loss (through conduction and convection) has been nearly eliminated.
Somebody will probably have this mentioned already but If i remember correctly the rate at which a vehicle degrades a road is also fourth power relationship with mass. So a car with mass of two times will degrade road 16 times more than the first car. Reddit had a TIL about it but I couldn't be bothered to check it myself.
I have a double walled cup with beeswax in the hollow space. Beeswax melts at roughly 65 degrees, meaning very fast cooling to this temperature as the wax changes state, followed by plateauing as the wax hardens again, around 55 degrees. Next step, get a triple lined cup, fill inner cavity with wax, leave outer as a vacuum = perfect tea!
This question was asked to class 7 students in India. In NSO exam.
2:28 another example is Rayleigh scattering. It says if a beam of white light travels through dusty air(micron size particles), the light constituents (wave lengths) scatter at different probabilities. The probabilities are proportional to the reciprocals of the wave lengths to the 4th power.
There are one thing that bathers me. You had different volume of water but the exact same volume of milk. that will make a difference in temperature. And also the fact that a smaller body have more area per volume unit than a bigger body with the same form. /Arvid
That's OK for tea but for instant coffee if you put the milk in first the coffee does not dissolve completely.
Also more importantly I always put the sugar in first if using the same spoon as the coffee because I like sugar in my coffee, but I don't like coffee in my sugar.
No matter how hot it is when the final cup of tea is assembled, there's still the same amount of time between when it's cool enough to drink and when it's too cool to drink. Therefore you should choose when to put milk in based on how soon you want to be able to drink the tea - put it in last if you want to be able to drink it as soon as possible, first if you're likely to forget it for a while and want it to still be hot when you remember it later.
I'm really not sure what the point of leaving it to sit without the teabag in is though, unless it's specifically to let it cool so you can drink it sooner; surely the whole point of waiting (whether before or after putting in the milk) is to let it brew.
ahhhhh the experinental inconsistency is real!
the amount to of boiling water in each cup was totally different! 😭
1. the proportion of milk is different which will schew the results.
2. the tea/water will have different surface areas. heat radiation is also proportional to surface area.
3. what was the temperature of the milk each time it was added. if it wasn't at identical temperatures the results will be inconsistent.
4. did you consider the effects of the liquids colour? we re not dealing with perfect black bodies here.
too inconsistent cannot publish!
that's me being mean! great video I ve only recently come across some of your stuff but I keep coming back! experimental methodology aside (I jest I assure you) this is one of my favourite videos of yours I ve seen. my other favourites are the excel spreadsheets as images. I also loved the talk on bar codes. oh! and the monopoly video was HILARIOUS. keep up the EXCELLENT WORK
I thought the "milk first or last" thing refers to adding the milk before the water? THAT is what people mean about it tasting different, because the milk is "blanched" by the hot water.
Interesting experiment nonetheless. Well done Matt, keep the videos coming, please!
The correct method (BS 6008) is to make the tea in a pot, add the milk to your cup, then pour the tea.
I have been a fan of your channel for ages, but just stumbled across this old video - how nostalgic!
It's a brew so if you are making it in the cup, you add the boiling hot water to the bag to get the most flavour out. If you are using a teapot, it matters not which way around you do it, however. you can keep adding milk to a strong tea to get it the way you like it, but you can't make it stronger by pouring in more water or tea if you started with too much milk.
My teacher taught me about stefan-boltzman equation today...and got to see this video today itself!....pretty awesome!
An aspect not covered by anyone so far is, as eloquently put in the video, radiant heat is proportional to T^4 difference to ambient. The two milk containers are not the same distance to the tea cups radiating heat, or shielded, or their temperature at least recorded.
Still, good experiment. I am reminded of the saying "Everyone's a critic". Yes, it seems we are. ;)
Cold spoon in the first cup, then it goes straight to the next cup when it's allready warm.
+ all other unwanted effects on this experiment!
But hey, it's a great video for making me think harder about biases and experimental errors! :)
I see that you stumbled upon the Parker experiment effect, in which the absolute difference in volume (in cm³) of molecules of H2O is smaller in the first container, and that the stirring utensil is used in the first container in room temperature, while in the second is used right after it being heated.
Lighten up guys, this man, Matt Parker, is a genius in communicating maths (his channel name speaks for itself). He is (possibly uniquely), a stand up mathematician, being both a mathematician and comedian. He is also, officially, the public engagement in maths fellow for the University of London. His stand up shows are both amazingly funny and thought provoking and lightning quick. So what if occasionally, he deiberately sets himself up, and some people think he is a bit of an idiot.... That's his JOB and he is very good at it. I teach maths, and have had any number of students who have been seriously switched on to maths since watching him. Once their enthusiasm is kindled, they will normally be able to equip themselves with the skills to determine whether something is strictly correct or not, in the meantime, haters will continue to hate, but he is doing way too much good for negative thoughts to be at all significant.
When the cup went ablaze I was dying. Lmao
Four variables to note.
First the mass of water was substantially different between the cups, I'm curious as to the practical effect on final temperature.
Second is the milk temperature relative to ambient and the magnitude of this on the final delta.
Third(somewhat related to the second) and more of a curiosity as it was properly controlled in this video and is worthy of its own experiment. Is that the milk was added to the water not the water to the milk in both cups, if cold milk is added to an ambient temperature cup, energy will flow from the cup into the milk lowering the temperature of the cup and causing some energy from the air to flow into the cup increasing the total energy of the system above that achieved by adding the milk to the hot water.
Fourth the brewing chemistry is altered both by the compounds added by the milk and the temperature, during the extraction phase.
I'm in the USA (near Tacoma/Seattle in a sea of coffee) I drink tea. No lemon, rarely honey or sugar, milk only in spiced Indian style teas; all styles(greens, oolongs, blacks, flavored, puh-err) as long as they aren't abused in brewing(eg off by an order of magnitude in grams per liter, steep time, or temperature for the style).
I have not confirmed the chemistry but I have heard milk will bind or otherwise neutralize the many friendly antioxidants in tea.
I think it is worth re doing for completeness. Proper volumes of hot water, tea bag temps, milk temps, different spoons per cup, cups at the same temps and so on. The maths only hold true in the real world completely if the real world is consistent and accurate. Love the maths btw