The Yerkes Observatory in Wisconsin holds the world's biggest refracting telescope. Weighing almost 6 tons, with a 40” main lens, it's so well balanced that it can be moved by hand.

Finished in 1897, no bigger one was ever made. What did we do instead?

The telescope thread… A refracting telescope uses convex lenses to focus light. Shown are the objective lens & eyepiece, with their respective focal distances: The ratio between these focal lens gives the magnification.

This also shows why the image in a simple refraction telescope is upside-down!

This is the NASA Ames low speed wind tunnel, the biggest in the world. It can fit full sized planes and takes up to 104MW of power to run!

But why use a wind tunnel, and what problems do you run into when trying to make it smaller? Let's go deep.

The wind tunnel thread… Why use one? For one thing, wind tunnels let you measure and visualize the flow field, using smoke, particle image velocimetry or a host of other techniques.

You can also directly measure the forces on your model with a force measuring ‘sting’ as shown.

An advanced Nuclear Power rabbit hole! This is not your father's atom bashing.

For your reading pleasure I've now covered five of the six Generation IV nuclear reactors: Clean, safe, hot running high tech beasts, the first have started arriving.

Let's go through them… Bringer of Alchemy: The molten salt fast reactor, thorium transmutation and the ‘infinite energy machine’.

In its liquid fuel form, it's definitely the most complex reactor type! But solid fuel, salt cooled reactors could appear soon.

Let's dive into the most Metal reactor of all! A high temperature nuclear reactor with a heart of liquid sodium.

Why cool a core with water when you can use molten metal?

The Sodium cooled fast reactor (SFR)! A GenIV reactor deep-dive… SFRs are expensive and complex, but they have interesting abilities, unlocking:

*Fuel breeding.
*Waste burning.
*Long periods between refuels.
*High temperature thermal cycles.
*Industrial process heat.
*Energy storage.

The death of steel.

Big ships are sturdy, but they're not immortal. Over time their maintenance costs soar until, after 30 years or more, they become more valuable as recycled metal and are sold to a scrapyard.

What happens next will surprise you… At the murky end of our supply chains lies this: The Chittagong breaking yards in Bangladesh, one of many places where old ships go to die.

But how is shipbreaking done,  what are the consequences, and is there a better way?

A thread.

What's Britain good at?

Is it an island of fog breathing has-beens, or a nascent industrial juggernaut? What, in fact, does Britain do well?

Here's a thread of a few surprising things…
Motorsport!

Almost all of the world's Formula 1 teams are based in this tiny region in Oxfordshire & Northamptonshire, which also supports 3,500 companies and 40,000 people in motorsport.

This is known as 'Motorsport Valley’ (not actually a valley).

Graphene!

The world's thinnest & strongest material, a one-molecule thick film of it could build a hammock that could hold up a cat, invisibly.

It was isolated 20 years ago, but what has happened with this super-material since then? And how do you mass produce it?

Read on... Graphene, a hexagonal one atom thick graphite crystal film, was theorised for decades but never characterised.

In 2004, Andre Geim & Konstantin Novoselov isolated & characterised a layer of Graphene in the University of Manchester using scotch tape (!)

And it's incredible.

Are you ready for BIG SCIENCE?

Not every scientific study involves drugged rodents or non-binary fish. Here's a selection of really massive, or just impressive, scientific projects for your viewing enjoyment.

Let's start… Fusion!

The National Ignition Facility was originally built to simulate nuclear bomb detonation, but has since fronted inertial fusion power research. In 2023 it first achieved controlled fusion ignition, producing more power from deuterium/ Tritium fusion than was applied.

The question you always wanted answered: How does a combine harvester work?

In this thread we take a dive into these awesome machines! The combine is among the greatest feats of automation in history, with one of the biggest effects on society. It freed entire towns & villages from the backbreaking toil of harvest and, with other innovations, took America from 90% of it's population in agriculture to 2% today.

The purpose of education is to tell the truth, right?

Not always. Sometimes it's to tell you a simplified fib, a not-quite-truth that almost explains things and prepares you for the truth as an adult.

This is a Lie-To-Children. Let's list a few, and you can add your own… We'll start small: Subtraction.

Young children are often taught, in math, to subtract the smaller number from the bigger number. This familiarises them with the concept, but makes negative numbers impossible.

Later on, we learn a more complex reality.

Reaction Engines and SABRE.

As some of you may know, a few days ago Reaction Engines went under. This was a company that for 30 years had been slowly developing a revolutionary hypersonic hybrid powerplant.

SABRE: What is it and why is it important? I'll do a proper deep-dive thread soon, but this is a taster:

SABRE is an engine designed to go from zero to orbital injection speeds while staying fuel efficient, unlike a rocket. 

It's a turbo-compressed air breathing hybrid rocket.

But why…?

Fighter aircraft!

They're warrior angels, six-winged Seraphim bringing wrath from above.

But why are these sky warriors the shape that they are?

Fighter plane aerodynamic design 101. There are a dizzying array of fighter aircraft in the skies now, but the more astute of you will have noticed recurring themes, and even entire countries with coherent design philosophies.

Is there a best approach, or is it horses for courses?

Let's look at the basics…

It's lightweight, corrosion resistant and ubiquitous. It's used in cookware, cars, rockets and aeroplanes, 

It's the most common metal on Earth, yet was once more valuable than gold.

It's very hard to make!

The metal that made our world: Aluminium! Read on… Aluminium is by far the most common metal in the Earth's crust, at over 8% by mass. Yet it's only been industrially exploited in it's pure form for a century and a half, and for a while it was a precious metal.

Why?

It's a beast to extract, and for high energy societies only.

The children's guide to Entropy.

Or: How I learned to stop worrying and love the heat death of the universe.

A thread, with pictures… Consider a simple question: Where does all the sound go?

If I stand on a hilltop and read Shakespeare, or even Harry Potter VERY LOUDLY, why can't someone at the other side of the world hear me very faintly a day later?

Why doesn't the world fill up with all our sound?

In this software-gilded age, let's pay tribute to the sullen monsters that keep the whole show on the road…

The beasts of burden that carry our entire industrial civilization…

Let's talk Heat Exchangers! Heat Exchangers (HX) are absolutely crucial to our hot-blooded world: On them we rely to generate our power, regulate our engines, cool our houses & thinking machines, create the chemistries for entire food chains.

Without them, we crash. And burn.

But how do they work?

25 little-known facts: A thread of things you probably don't know!

1:
The differently-coloured tip at the front of a commercial jet engine is frequently rubber, and a de-icing measure: It distorts under even slight asymmetric load, throwing off ice before it forms big clumps. The sharpest object in the universe…

Electrolytically etch a necked tungsten needle in potassium hydroxide and the interaction between geometry & electric field strength creates a tapered tungsten nanoneedle.

These have been made to taper down to the atomic level.

When nuclear reactors are too blasé and you want to bend physics to your will…

Why not cool a reactor core with a fluid compressed & heated to such extremes that it's no longer a liquid or a gas but something else entirely.

It's the Supercritical Water Reactor thread! Most reactors in operation today are light water reactors, and there are good reasons for that: Water is both moderator & coolant, they have safe negative reactivity coefficients and decently high power density.

However they are complex and limited by temperature & efficiency.

Nuclear power: Is it the future or outmoded technology? Let's take a look at five Generation IV designs and maybe take some inspiration.

Which is your favourite?

A nuclear rabbit hole for your weekend… What we're building right now are Generation III pressurised water or boiling water reactors. They're sturdy and mature, if a tad expensive.

The GenIV reactor designs share some features: Passive safety, simplified architecture, less waste and (hopefully) lower costs.

Let's learn about a technology that saved billions of lives and enabled the modern world!

And let's learn about the darkness in the soul of one man.

Beyond Good & Evil? You be the judge.

The Haber-Bosch process…

Be warned: By the end of this thread you will need to stand in judgement of a man and decide for yourself whether he was a saint or a monster.

You might even owe your life to him. That makes it tricky.

But first, we shall start at the beginning…

In January 1930, with the Great Depression strangling the world, a 22 year old Frank Whittle patented the turbojet.

The patent lapsed in 1934 when he couldn’t afford the £5 renewal, but by then the world was changing.

The story of the jet engine, in a single thread… Something new…

The Whittle engine comprised two axial compressor stages and a centrifugal compressor, powered by a turbine following the combustor. 

The use of a centrifugal compressor would become a key differentiator. Other turbojets favoured axial compression.

What is Supercritical CO2?

You're about to learn of a technology that will change the world and how we generate energy.

It's not quite a liquid and not quite a gas, but it's all Miracle!

Get ready: We're going deep on this one… Earlier this year, the SwRI in San Antonio generated electricity from a closed cycle supercritical CO2 powerplant. Why is this important?

Because it's a super high efficiency technology that cleans & miniaturizes the thermal heat engines we use to power… Everything.