A Pressure Cooker for Tea


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I’m not a tea-drinker1. But while making a cuppa for Ruth this morning, a thought occurred to me and I can’t for a moment believe that I’m the first person to think of it:

What about a pressure-cooker, but for tea?2

Hear me out.

A pressure cooker whose digital display reads 'tea'.
Modern digital pressure cookers have a lot of different settings and modes, but ‘tea’ is somehow absent?

It’s been stressed how important it is that the water used to brew the tea is 100℃, or close to it possible. That’s the boiling point of water at sea level, so you can’t really boil your kettle hotter than that or else the water runs away to pursue a new life as a cloud.

That temperature is needed to extract the flavours, apparently3. And that’s why you can’t get a good cup of tea at high altitudes, I’m told: by the time you’re 3000 metres above sea level, water boils at around 90℃ and most British people wilt at their inability to make a decent cuppa4.

It’s a question of pressure, right? Increase the pressure, and you increase the boiling point, allowing water to reach a higher temperature before it stops being a liquid and starts being a gas. Sooo… let’s invent something!

Illustration showing key components of a pressure-tea maker.

I’m thinking a container about the size of a medium-sized Thermos flask or a large keep-cup – you need thick walls to hold pressure, obviously – with a safety valve and a heating element, like a tiny version of a modern pressure cooker. The top half acts as the lid, and contains a compartment into which you put your teabag or loose leaves (optionally in an infuser). After being configured from the front panel, the water gets heated to a specified temperature – which can be above the ambient boiling point of water owing to the pressurisation – at which point the tea is released from the upper half. The temperature is maintained for a specified amount of time and then the user is notified so they can release the pressure, open the top, lift out the inner cup, remove the teabag, and enjoy their beverage.

This isn’t just about filling the niche market of “dissatisfied high-altitude tea drinkers”. Such a device would also be suitable for other folks who want a controlled tea experience. You could have it run on a timer and make you tea at a particular time, like a teasmade. You can set the temperature lower for a controlled brew of e.g. green tea at 70℃. But there’s one other question that a device like this might have the capacity to answer:

What is the ideal temperature for making black tea?

We’re told that it’s 100℃, but that’s probably an assumption based on the fact that that’s as hot as your kettle can get water to go, on account of physics. But if tea is bad when it’s brewed at 90℃ and good when it’s brewed at 100℃… maybe it’s even better when it’s brewed at 110℃!

A modern pressure cooker can easily maintain a liquid water temperature of 120℃, enabling excellent extraction of flavour into water (this is why a pressure cooker makes such excellent stock).

A mug of tea held by the handle.
It’s possible that the perfect cup of tea hasn’t been invented yet, owing to limitations in the boiling point of water.

I’m not the person to answer this question, because, as I said: I’m not a tea drinker. But surely somebody’s tried this5? It shouldn’t be too hard to retrofit a pressure cooker lid with a sealed compartment that releases, even if it’s just on a timer, to deposit some tea into some superheated water?

Because maybe, just maybe, superheated water makes better tea. And if so, there’s a possible market for my proposed device.


1 I probably ought to be careful confessing to that or they’ll strip my British citizenship.

2 Don’t worry, I know better than to suggest air-frying a cup of ta. What kind of nutter would do that?

3 Again, please not that I’m not a tea-drinker so I’m not really qualified to comment on the flavour of tea at all, let alone tea that’s been brewed at too-low a temperature.

4 Some high-altitude tea drinkers swear by switching from black tea to green tea, white tea, or oolong, which apparently release their aromatics at lower temperatures. But it feels like science, not compromise, ought to be the solution to this problem.

5 I can’t find the person who’s already tried this, if they exist, but maybe they’re out there somewhere?

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Science Weekend

This weekend was full of science.


String of large electromagnets used for steering an electron beam.
If you wanna bend a stream of electrons travelling at nearly the speed of light, you’re gonna need a lot of big magnets.

This started on Saturday with a trip to the Harwell Campus, whose first open day in eight years provided a rare opportunity for us to get up close with cutting edge science (plus some very kid-friendly and accessible displays) as well as visit the synchrotron at Diamond Light Source.

Dan with a child in front of beamlines coming out of the Diamond Light Synchrotron ring.
It’s hard to convey the scale of the thing; turns out you need a big ol’ ring if you want to spin electrons fast enough to generate a meaningful amount of magnetobremsstrahlung radiation.

The whole thing’s highly-recommended if you’re able to get to one of their open days in the future, give it a look. I was particularly pleased to see how enthused about science it made the kids, and what clever questions they asked.

For example: the 7-year-old spent a long time cracking a variety of ciphers in the computing tent (and even spotted a flaw in one of the challenge questions that the exhibitors then had to hand-correct on all their handouts!); the 10-year-old enjoyed quizzing a researcher who’d been using x-ray crystallography of proteins.


And then on Sunday I finally got a long-overdue visit to my nearest spirometry specialist for a suite of experiments to try to work out what exactly is wrong with my lungs, which continue to be a minor medical mystery.

Dan holds a piece of medical apparatus to his mouth.
“Once you’ve got your breath back, let’s fill you with drugs and do those experiments again…”

It was… surprisingly knackering. Though perhaps that’s mostly because once I was full of drugs I felt briefly superpowered and went running around the grounds of the wonderfully-named Brill Hill Windmill with the dog until was panting in pretty much the way that I might normally have been, absent an unusually-high dose of medication.

Computer screen graphs showing peak respiratory flow under a series of different experiments.
It’s got a graph; that makes it science, right? (I’m ignoring those party political histograms that outright lie about how narrow the margins are…)

For amusement purposes alone, I’d be more-likely to recommend the first day’s science activities than the second, but I can’t deny that it’s cool to collect a load of data about your own body and how it works in a monitorable, replicable way. And maybe, just maybe, start to get to the bottom of why my breathing’s getting so much worse these last few years!

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Einstein’s theory still passes the test: weak and strong gravity objects fall the same way

This article is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Fabulous explanation of the Strong Equivalence Principle coupled with a nice bit of recent research to prove that it holds true even in extreme gravitational fields (and therefore disproving a few interesting fringe theories). It’s hard science made to enjoy like pop science: yay! Plus a Hitch-Hiker’s Guide to the Galaxy reference, to boot. Under 10,000 views; go show them some love.