Shadowing Practice: He Realized his Mistake - Learn English Speaking with Video
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Of all the legendary computer scientists, Tony Hoare stands distinct among them all.
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Let's just put it this way.
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70 % of all enterprise
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Java errors that have been logged can be attributed to a single decision he made in 1965.
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In fact, one of the largest Google outages in recent memory was caused by a null pointer exception.
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We're talking about a basic if statement was skipped and seven hours of downtime was experienced with three hours globally affecting many, many services, including Spotify.
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Costing many millions in damages, and all of this could be traced back to that one 1965 decision.
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But it's not all epically bad decisions from Sir Tony Hoare.
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He's also created some of the fastest and most memory -efficient sorting and statistical algorithms.
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And his professional and academic work have laid the foundations for languages like Pascal and Go.
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I know, some of you think
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Go's a blunder, but he made the good parts.
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And throughout his career, he has been honored slash awarded more than 21 times,
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including the Turing Award, some consider the highest award in all of computer science, and he was knighted for his contribution to education and computer science.
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But today, he receives the most prestigious honor of them all.
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Programmer of the month at the startup.
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Being knighted, programmer of the month.
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But before we remember
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Tony's greatest disasters and achievements, a quick thank you from the sponsors.
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The next 100 billion commits are coming faster than planned for.
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Is your CI up for the challenge?
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Today's CI requires new infrastructure built for one thing, reliability and performance.
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Blazingly fast.
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Namespace optimizes for fast coding, test, and build environments.
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It's their singular focus.
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That focus runs down to the metal.
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From server racks they design and deploy worldwide, to products built on foundations like dev boxes and GitHub Action Runners available on Windows, Mac, and Linux.
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They actually have Mac.
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Crazy.
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They are used by Ramp, Vanta, Warp, Framer, Zed, Fowl, Sierra, Whisperflow, DuckDB, and even Ghosty uses them.
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You can join them and try it out today at namespace .so.
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Sir Charles Anthony Richard Hoare was born January 11, 1934 in what is now known as Sri Lanka.
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He was educated in England at the finest of schools.
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We are talking, of course, about the Dragon School in Oxford and the King School in Canterbury.
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they serve tea
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and fine fine table cookies i don't
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i don't even know what they do with those type of places
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it sounds very fancy okay i went to montana state university okay
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i'm not allowed to have these type of experiences later on he entered merton college in oxford in 1952
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and after graduating he spent 18 months studying russian of course
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he had to do this as part of his compulsory duty to the royal navy
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now this is where it actually gets pretty interesting because during his time in Russia at Moscow State University.
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Also looks like he went to MSU like I did.
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Go Bobcats for here!
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Before I show you Quicksort, I did want to just say that
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Tony Hoare raw dogs this on a pen and piece of paper in the middle of Russia.
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Okay, there was no computer.
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There wasn't even a programming language with recursion at the time of him inventing this.
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It's like he has chat GPT in his head.
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He can just close his eyes and imagine problems and get answers out of it.
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Quicksort's actually rather easy to understand.
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You pick an element, any random element.
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I just picked the middle element.
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And then you put everything that is smaller on one side and everything that is larger on the other side.
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After that, 14 is now sorted.
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Everything on the left -hand side is smaller.
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Everything on the right -hand side is larger.
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So if we do it again, we just consider the smaller side.
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Again, we just pick the middle element.
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We sort, and there you go.
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7 and 3 are now sorted.
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We do it again, pick the middle element, put everything smaller on the right, everything larger on the left, 11 is now sorted.
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And since there's only one on the left, 13 is now sorted.
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Do the same thing again.
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They're both sorted.
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Jump over to the other side.
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Go in the middle.
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Everything smaller goes on one side.
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Everything larger on the other side.
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Bada bing, bada boom.
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That is quick sort.
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Okay, so you're probably thinking, what's the big deal?
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It's just sorting.
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It's not even that awesome.
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Well, actually, first off, it was very, very awesome.
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I want to put a little couple things in perspective.
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First off, runtime.
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It has n log n for runtime, meaning that its growth, as the array gets bigger, will become proportional to N log N.
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So that's actually pretty dang good.
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Second, it does not require a lot of memory.
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Now, this is very, very important because back in the day, back in the old days in 1960, one kilobyte of RAM, magnetic core RAM,
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was $5 ,000 in the old US dollars, which means in today's dollars, that's like $50 ,000 per kilobyte.
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Who would kill a byte for $50 ,000?
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So as you can see, this is extremely important.
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Now, he never actually got the chance to implement this.
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This was just a pure thought exercise for a long, long time.
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Until one day when he joined the Elliott Brothers in 1960 and his very first task was to implement Shellsort.
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Now, of course, him being the confident fella he is, he went to his boss, which he has named Pat.
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And he went, hey, yo, boss, uh, shell sword sucks.
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I could make it much, much better.
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And his boss was like, there ain't no way you're gonna make it any better.
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And they actually ended up betting six pence.
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I don't know what six pence is.
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That sounds like something out of a nursery rhyme.
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I don't know what's going on over in the UK or whatever they're doing over there.
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But nonetheless, they bet a few dollars on the line or many dollars, or I don't know how many dollars that is.
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What is it in freedom units?
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I don't know.
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Anyway, so they bet.
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And then whore ends up getting on the whiteboard and starts drawing out some boxes and arrows and explains his algorithm.
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His boss, Pat, implements the algorithm, admits he is wrong, and later
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Tony Hoare does say that he was given six pence for winning the argument.
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During his time at Elliott Brothers, he also convinced them to implement Algo 60 as opposed to their own bespoke proprietary language.
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This proved to be a large commercial success, and Tony was showered with accolades.
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Obviously, implementing Algo 60, he got really excited about it, and a few years later,
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he started working on a language with Nicholas Wirth called Algo W, a successor to Algo 60.
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Now, it's his work on Algo W that became so quintessential to all of our lives.
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The emotional damage you have experienced can be traced back to these decisions right here.
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Let me read you the abstract from his QCon talk in 2009.
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I call it my billion -dollar mistake.
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It was the invention of the null reference in 1965.
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At the time, I was designing the first comprehensive type system for references in an object -oriented language, ALGOL W.
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My goal was to ensure that all use of references should be absolutely safe.
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Hilarious, okay?
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I mean, we're talking about null references here, people.
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I just, my heart is warm to be like, we're going to make it absolutely safe.
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No references.
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With checking performed automagically by the compiler, but I couldn't resist the temptation to put in a Null reference.
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I mean, this guy is having like a Lord of the Rings level style temptation.
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He just couldn't.
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The ring was too powerful.
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Null references is, in fact, the power of Sauron.
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Simply because it was so easy to implement.
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This had led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last 40 years.
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The real question is, how costly was the Null Pointer decision?
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Well, first off, as a student at MSU Go Bobcats, I will tell you that I spent many a day trying to debug damn null references.
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Okay, so emotionally, it was like a billion dollars just for me.
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But I think
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that you can recall a time just a couple years ago
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where the world's largest outage could be traced back to a null reference.
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One of the most famous ones was from June 12, 2025 from Google Cloud.
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Effectively, all it was was they just didn't check for a null pointer.
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And of course, null pointer happened.
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API and auth went down and then globally everything just did not work.
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And of course this went on for about seven and a half hours until the fix was fully rolled out.
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There's just something that tickles me that I find so funny about this entire situation in which
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Tony Hoare over here, he just wanted to be able to create a type safe language
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that was absolutely safe with all references and ends up creating the greatest debacle that we're still recovering from to this day.
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The reality probably is that
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if he did not invent it somebody else would have just like the AI race really
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it's just like the exact same thing
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but at the end of the day it is attributed to him
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and his algo w work
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now one of his largest contributions to the field of computer science would be communicating sequential processes
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now I'm just going to demonstrate a quick example of what this means in practice by showing
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you a little bit of code
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and go now I know a lot of you are rust boys out there
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and you're probably a little upset
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that I'm using go just just just walk with me because it's the simplest all right so we have two processes here.
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We have this outer process, which creates a channel, waits on the channel, and then prints out the message it gets from a channel.
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We have a second process that's going to do some work
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and then ultimately hand that work out in which I'm calling Hello World.
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So that means we create the channel in process one.
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Process two is going to just start executing.
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Process one now is just going to be waiting.
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It's going to be waiting synchronously until process two communicates.
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This is a very important part of communicating sequential processes.
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Then finally, when the work is done in process two and we can now communicate,
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now process one receives the message and is able to move forward.
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So one of the core ideas of CSP is that communication is a synchronous handshake.
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And as you can see right there, process one had to wait until process two communicated.
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So both process two and one have to wait for each other because the communication is synchronous.
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Now, obviously, you can get around this by creating buffers.
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That way process two can theoretically send more messages.
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But the simple idea is that all processes have to communicate in a synchronous handshake.
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That processes are units of behavior and do not share variables.
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Now, I know in that
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Go example, I did do a little bit of sharing, but we can just ignore it for now.
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Again, I'm just explaining this in the most simple and obvious practical terms, not really in the calculus side of things.
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You can go look up the calculus
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and how events are supposed to be instantaneous
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and how.. receivers are supposed to have an alphabet in which they are the type of events that they receive.
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If you've ever done any elixir, this probably sounds pretty dang familiar to the actor pattern because, well, I mean, it is.
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So at the end of the day, Tony Hoare's contributions to computer science have been actually quite a bit more than I even threw out there.
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I didn't even talk about Quick Select and some of his statistical algorithms
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that he helped accomplish his practical work on the Algol compiler.
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Much like his predecessor, Edgar Dykstra, who also was a recipient of the Programmer of the Month Award,
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he has a few banger quotes that I'd like to read for you.
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When he thought and talked about ALGOL 60, he said the following,
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Here's a language so far ahead of its time that it was not only an improvement on its predecessor,
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but also nearly on all of its successors.
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The man had a way with words.
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There are two ways of constructing software design.
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One way is to make it so simple that there are obviously no deficiencies,
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and the other way is to make it so complicated that there are no obvious deficiencies.
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The first method is far more difficult.
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Oh my gosh, the man can see around corners if he, he was, he technically did die this year in March,
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but I'm sure he saw some of what the AI was doing, and I wonder what he thought about this right here,
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and just the massive amounts of code we have produced.
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Later in Tony Hoare's career, he received the second most honorable distinction, being knighted by Queen Elizabeth II, which is why we actually call him
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Sir Tony Hoare.
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Of course, if you didn't know, Program of the Month being the most important designation one can possibly get.
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Now, I did not get to all of Tony Hoare's amazing accomplishments and the things that he had done.
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I didn't even talk about Quick Select.
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I didn't even talk about all the cool work he really did on Algo W
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or about his unifying theory of programming or the philosopher's dining, which, by the way, the dining philosopher's problem, Pretty gross that they're sharing silverware, okay?
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I didn't even want to talk about it because it's unsanitary.
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But at the end of the day, Tony Hoare's influence will be felt for a very, very, very long time.
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And it's quite obvious he deserves
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Programmer of the Month.
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So here's to you, Sir Tony Hoare, Programmer of the Month.
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The name is the Primogen.
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Vocabulary and speaking notes for this lesson
This speaking lesson is built on the video “He Realized his Mistake”. The speaker keeps coming back to these words: Tony, process, null, reference. This video has 202 sentences and 2382 words to shadow. The speech runs for 12:14. The speaker talks fast, about 195 words per minute, so expect linked and reduced sounds. Only 81% of the words are among the 3,000 most common in English, so the vocabulary is demanding.
Key vocabulary in this video
15 words from the video worth learning, with pronunciation and meaning:
| Word | Pronunciation | Meaning |
|---|---|---|
| algorithm noun | /ˈælɡəɹɪðm̩/ | A collection of ordered steps that solve a mathematical problem. A precise step-by-step plan for a computational procedure that possibly begins with an input… |
| null noun | /nʌl/ | A non-existent or empty value or set of values. |
| communicate verb | /kəˈmjuːnɪkeɪt/ | To impart or transmit (information or knowledge) to someone; to make known, to tell. |
| implement verb | /ˈɪmpləmənt/ | To bring about; to put into practice; to carry out. |
| element noun | /ˈɛləmənt/ | One of the simplest or essential parts or principles of which anything consists, or upon which the constitution or fundamental powers of anything are based. |
| programmer noun | /ˈpɹoʊɡɹæmɚ/ | One who writes computer programs. |
| pointer noun | /ˈpɔɪn.təɹ/ | One who points. |
| contribution noun | /ˌkɑntɹɪˈbjuʃən/ | Something given or offered that adds to a larger whole. |
| knight noun | /ˈnaɪ̯t/ | An armored and mounted warrior of the Middle Ages. |
| trace noun | /tɹeɪs/ | An act of tracing. |
| penny noun | /ˈpɛni/ | In the United Kingdom, a unit of currency worth ¹⁄₁₀₀ of a pound sterling, or a copper coin worth this amount. Abbreviation: p. |
| practical adjective | /ˈpɹæk.tɪ.kəl/ | Relating to, or based on, practice or action rather than theory or hypothesis. |
| statistical adjective | /stəˈtɪs.tɪ.kəl/ | Of or pertaining to statistics. |
| successor noun | /səkˈsɛsɚ/ | A person or thing that immediately follows another in holding an office or title. |
| globally adverb | /ˈɡloʊbəli/ | In all places or situations. |
Phrasal verbs you will hear
| Word | Pronunciation | Meaning |
|---|---|---|
| end up verb | To bring to a conclusion. | |
| do over verb | /ˈduˌoʊvɚ/ | To cover with; to smear or spread on to. |
| draw out verb | To make (something) last for more time than is necessary; to prolong; to extend. | |
| get around verb | To move to the other side of (something, such as an obstruction) by deviating from a direct course or following a curved path. | |
| go down verb | To descend; to move from a higher place to a lower one. | |
| look up verb | /ˌlʊk ˈʌp/ | To have better prospects. |
| move forward verb | To cause to make progress. | |
| print out verb | To print (a computer document). |
Sentences worth repeating
Short, complete lines from the video that you can reuse in everyday conversation:
- Let's just put it this way.
- Okay, so you're probably thinking, what's the big deal?
- I don't know what six pence is.
- I mean, we're talking about null references here, people.
Grammar in this video
The structures the speaker uses most, with the exact words from the video:
| Structure | In the video |
|---|---|
| Passive voice be + past participle — the focus is on what happens, not who does it | have been logged · was caused · was skipped |
| Present perfect have/has + past participle — a past action that still matters now | have been logged · have laid · has been honored |
| Relative clauses who / which + clause — extra information about a person or thing | dollars, which means · crashes, which have |
Pronunciation to watch
The speaker uses 35 contractions and reduced forms, such as didn't, don't, I'm. Say them the short way, as you hear them.
- The “th” sounds: algorithm /ˈælɡəɹɪðm̩/, nonetheless /ˌnʌnðəˈlɛs/, authorization /ˌɔːθəɹaɪˈzeɪʃən/
- The “sh” and “zh” sounds: contribution /ˌkɑntɹɪˈbjuʃən/, temptation /ˌtɛmpˈteɪʃən/, deficiency /dɪˈfɪʃənsi/, efficient /ɪˈfɪʃənt/, shell /ʃɛl/
- Long words — get the stress right: communicate /kəˈmjuːnɪkeɪt/, contribution /ˌkɑntɹɪˈbjuʃən/, statistical /stəˈtɪs.tɪ.kəl/, predecessor /ˈpɹɛd.ə.sɛs.ɚ/, deficiency /dɪˈfɪʃənsi/
How to practise with this video
- Listen to the whole video once without speaking and note the words you do not know.
- Start at 0.75× speed, shadow it sentence by sentence, then go back to normal speed once it feels easy.
- Record yourself and compare with the original, paying attention to words like algorithm, null, communicate.
What is the Shadowing Technique?
Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.