Would "Someone" Breaks The Undersea Internet Cables?

Not that they would, of course. Any more than they would blow up their own gas pipeline, or break a dam that mostly supplied water to parts of a country it is occupying, but I digress...

Should "someone" start breaking up the undersea cables that carry all those cat pics and Tik Toks we all love so much, what happens?

Your online banking will still work. That runs over Openreach's UK domestic network.

The retail banks have their own private networks. So do the railways and the armed forces. The NHS has a small flock of under-fed carrier pigeons.

All the big companies have copies of their websites disbursed to servers over the world. Amazon will still be up and running. Some services may not work, but we will still be able to buy Chinese junk from it, as long as that junk is physically in the UK.

Your fixed-line calls to domestic numbers either go over Openreach or Virgin's network. Your mobile calls to domestic numbers go over your carrier's mobile domestic network. So you can still send messages saying you have to cancel.

Anyone who really needs international comms will have satellite capacity on standby, as well as redundant undersea capacity in all directions.

So I think that business carries on as usual, but they will use it as an excuse for even poorer service, even if they are not affected.

You can find a detailed map of the world's undersea cables here. It's not a secret. Take a look and it becomes obvious that there are a handful of landing points in each country. Send a special ops team out to blow those up. Or you could follow the land lines back to one of a smaller number of data centres / telehouses, and blow those up. You could always hi-jack an airliner and fly it into one. If that's too extravagant, hire a trawler and sail it past those landing-points trailing a great big net behind you. That's worked any number of times in the Mediterranean over the years. Breaking the cables in the open sea needs submarines and trained divers, so that cuts the suspects down to a short list.

Still. Breaking some ocean internet cables. Sounds bad.

Maybe even as recently as fifteen years ago it would have been. The capacity and the number of cables available today is beyond any projection anyone would have made in 2008. To make a noticeable difference a saboteur would need to break a dozen or so cables on several different coasts within a week of each other. Undersea cables are easier and cheaper to repair than a gas pipe.

More importantly, there's no cyber warfare if there's no cyber-connection to the enemy.

99A Charing Cross Road

 

I never realised just how Art Deco that building is above the shop level. Did they clean the exterior during the lockdown?

Why Les Paul Volume Controls Affect Both Pickups When Selector Is In Middle Position

The Les Paul has two pickups, each of which have their own volume and tone controls. The iconic selector switch is at the upper segment of the body and has three positions: Treble (down) for the Bridge pickup, Rhythm (up) for the Neck pickup, and middle which uses both pickups.

With the switch set for the Neck pickup, the Bridge controls have no effect on the sound - as you would expect. With the switch set for the Bridge pickup, the Neck controls have no effect on the sound. Put the switch in the middle, and turning either volume control down to about 1 or lower shuts off the signal from both pickups, no matter how loud the other one is set to.

Wha? Huh? Is it broken? No. It's a feature. (Which I spent the better part of a Sunday understanding.)

FACT ZERO: the pickup-> volume control -> tone control -> selector switch circuits are wired in parallel.

FACT ONE: The volume controls are potentiometers, not variable resistors. A potentiometer has three tabs: input, output (attached to the variable control) and ground return. A variable resistor has two tabs: input and output. This matters. Were we to put a current in via the output tab (sounds odd, but no harm will result), a potentiometer provides two circuits: one to the input tab, and one to the ground return tab. Each one of those has a resistance: R_in and R_gnd, and R_in + R_gnd = 500k ohms always, at least on Les Pauls.

This will be important in a couple of paragraphs.

FACT TWO: don't forget the most important circuit in any guitar, the one out to the pre-amp, which takes a louder copy (that's what amplifiers do), and lets the original current go back into the guitar return circuit. That amplifier circuit has a resistance, R_amp.

Back to the Selector Switch. When it is in the centre, both output lines are connected.

Read that again!

When the switch is in the centre, both the output wires from the volume controls are connected. The output tab of the Neck pickup is connected to the output tab of the Bridge pickup.

So by facts ONE and TWO, the output tab of each volume control sees three circuits:

1) to the amplifier, resistance R_amp

2) to the other volume control and out through the ground return, resistance R_gnd

3) to the other volume control and out through the input tab, resistance R_in

This is where the magic happens. As we turn down (say) the Bridge volume, we are increasing R_in and therefore decreasing R_gnd because that's what happens in a potentiometer. Keep turning the volume on the Bridge down, and Rgnd will become close to and then much lower than R_amp. At which point hardly any current is going to the amplifier, because it is following the path of least resistance, Rgnd, and the guitar sounds as if it's been turned off.

Which was required to be proved.

This does not happen with Strats and Teles because the selector switch is before the pots in a Fender, and the connection to the pots is made by the same wires from the switch frame, no matter what position the switch is in.

(Some gnarled old electrical engineer at Gibson no doubt took one look at the mock-up of the Les Paul circuitry and said "Very nice, if you want one pot to ground through the other at low volume when the switch is in the middle." And everyone shook their heads and thought, there goes Old Joe again. Until it happened.)

Sunny Day - Mystery Location

 Where is this quiet bucolic place in the countryside? A little hint of Victorian brickwork, some modern lights, and a single-track railway. 

Highlight below to see the answer.

Crystal Palace

Johns Hopkins University on the UK Lockdown

Prof Steve Hanke from Johns Hopkins University, in the US, Dr Lars Jonung, from Lund University, Sweden, and Jonas Herby, special adviser at the Centre for Political Studies (CEPOS), recently completed a study that showed, to exactly no-one's surprise, that during the first wave of the pandemic (March - June 2020, but they don't say specifically) 1,700 lives were saved buy the lockdown measures. They say that Government-imposed lockdowns were un-necessary, because people would have adjusted their behaviour.

In other words, the Government didn't need to impose a lockdown, because the people would have imposed their own. This was pretty much what happened in Sweden.

Sweden, by the way, has one million more people (10m) in it than London (9m). The UK has 63m people. One of those countries is not like the other.

What would have been the economic damage of leaving the people to decide for themselves, but with Local Government continuing to charge the Business Rate, and landlords continuing to charge rent? It does not take much of a loss of business before a cafe or cinema can't pay rent and business rates, and it does not take much more before the balliffs or the bank come thundering in. Railways must run, or trees will grow through the tracks, so public transport would have needed subsidising. I don't know what the numbers would look like, but I do know that much of the economic activity in the UK relies on low wages, debt, and overdrafts.

What happens if a nurse decides she doesn't "feel safe" going in for her shift? Or a policeman? Or a supermarket lorry driver? Or a sewage plant maintenance man? Or the people who run your local pharmacy? Would employers be able to sack workers who "didn't feel safe"? With every other Government in the world telling people there's a killer virus on the loose? Even if employers could "hibernate" concerned workers, who would replace them? Would businesses lay off people in anticipation of a loss of income? And what do those people do for money, since employment has dropped?

You can feel the chaos already.

But... divide the workforce into two, with "non-esssential" workers forced to "work from home", and the "essential" workers are, by contrast, required to show up at the hospital, depot, supermarket, bus garage, sewage plant, power station, and so on. Declare an emergency and Councils can be made to hold back on the Business Rate, landlords on rents (some of the better ones, not the De Walden Estate), while furlough can be paid to keep people in money...

The correct comparison is what the figures would have been if the UK had carried on as usual, with white-collar workers adopting in-the-office schedules and working from home otherwise. Businesses, shops, cafes, restaurants, gyms, swimming pools, cinemas, theatres, and the like all open as usual. No restrictions. Anyone who gets the symptoms, stays home for five days. (We should be doing that anyway!) The Government makes it clear that: a) you cannot sue anyone if you caught the Virus on their premises; b) you will be sent to Re-Education HR for an "assessment" if you claim to be that scared of getting what is actually a bad case of the flu that almost everyone will survive.

And someone would have needed to shut those whining, hand-wringing journalists up. Let's not forget, it was Piers f******g Morgan who bullied the Prime Minister into making the Police enforce lockdown, which the Police did not want to do.

My guess is that even a part-time working-from-home / office regime would hit the town-centre businesses the same way it has now, a lot of marginal business would still have closed, and many managements would have used the opportunity to rationalise.

If the Virus had struck in 2010, nobody would have been working at home, because the internet / broadband infrastructure was just not good enough. But in 2010, people still had their own desks in the open-plan offices, and more space around them, compared to the crammed offices of 2019, so they would not have adopted working from home with the same enthusiasm. A curfew on social life would have been impossible to justify: if it's not safe to go to the movies, it's not safe to go to work. Maybe some restrictions on the number of people in social spaces could have been imposed. We would have worn masks in public spaces (but not offices), but not as a badge of our virtuous compliance, but as a nuisance just to keep the b****y Government happy. A lot more people would have had a bad few days, and then enjoyed subsequent immunity. The kids would have stayed at school. Families would have been able to see each other, and attend funerals and weddings as they should.

We cannot use the Swedish figures as a proxy for "no lockdown" because the Swedes put themselves into a self-imposed lockdown and the population density is lower. What we do know is that almost nobody died solely from the Virus: they died - often painfully and tragically - because they had other conditions, and the Virus was one too many. This was known from the start. Because of that, the additional deaths would have been smaller. In fact, from what we know already, if the transfer of older people into care homes had been done with the slightest bit of care, there may have been fewer deaths.

Deep In Epping Forest

 About halfway round the Holly Trail there's an area of what may be marshland if it gets wet. They don't want you riding horses over it. This scene is part of that. Heaven knows where the water comes from: the area around it is bone-dry.

How To Translate Faraday's Law of Induction into Math

I know what you're thinking. What does he get up to that stops him posting promptly and prolifically? I wish it had something to do with Instagram models and / or  staying up late making music via Garageband, but it is much more mundane than that. Here's a short passage about the translation of Faraday's Law of Induction into mathematical notation that I've been working on for far longer than you might think. If I've done my job well, it should seem obvious. (Some of the original \LaTeX has been butchered to accommodate Blogger.

(starts)

Faraday's Law, more or less as stated by Faraday, is: the electromotive force around a closed path is equal to the negative of the time rate of change of the magnetic flux enclosed by the path. How does this get translated into mathematical notation? We need to know that the `electromotive force' is, in the case of magnetic induction, the work done on an elementary electric charge (such as an electron) travelling once around the loop. Work done moving along a path is always a line integral of the product of a force and a displacement (since `work = force times distance').

As a first step, we re-name those things as variables or constants:

let $\mathcal{E}$ be the electromotive force

let $B$ be the magnetic flux

let $\partial A$ be the path, enclosing an surface A

let $ds$ be a small displacement along $\partial A$

let $E$ be an electric flux field

We can write down the equations quite easily if we are familiar with the vector calculus. Work done is given by the mantra `work = force times distance'. For a small displacement $ds = (dx, dy, dz)$ and a force $E = (E_x, E_y, E_z)$ the product is $E_x dx + E_y dy + E_z dz$ which is $E \cdot ds$ in vector notation. The work done along a line is the sum of such displacements along it, which is conventionally shown by the integral $\oint_{\partial A} E \cdot ds$, giving us $\mathcal{E} = \oint_{\partial A} E \cdot ds$.

Translating the other side of Faraday's Law, Faraday thought of electromagnetic fields as `lines of force' - the more lines, the more force - and the flux of a field through an area was the number of lines of force through it. This was Faraday's way of thinking about line and surface integrals without having to actually use either. 

The number of lines of force within a path is the integral of the (strength of the) vector field over any smooth surface enclosed by that path. (The `any' has to be proved, but it is becomes intuitively obvious after visualising a few examples.) So if we take a surface $A$, divide it into non-overlapping patches $dA(n)$, calculate $\frac{\partial B}{\partial t}(n)$ for the centre of the $n$-th patch, and add the total, we get an estimate of the electromagnetic field strength. Make the patches smaller, and we get a better estimate, which in the limit is the integral 

$\mathcal{E} = -\iint_{A} \frac{\partial B}{\partial t} \cdot dA$

That can also be turned into a conventional double integral by substituting coordinates. Hence Faraday's Law of Induction is translated into mathematical notation as

$ \oint_{\partial A} E \cdot ds = -\iint_{A} \frac{\partial B}{\partial t} \cdot dA$

The left-hand side is the work done, and the right hand side is the negative of the time rate of change of the magnetic flux enclosed by the path. This completes the translation of Faraday's Law into mathematical notation.

This is no more conceptually complicated than if we had translated, say, a passage of Freud from German to English. There is no word-for-word mapping of the two languages, and there are many concepts for which there is a German word, but not an English one, and one must attempt to explain the German concept in English. Using an integral to denote the result of a limit of finite sums is no more exceptional that using a derivative to denote the result of take rates-of-change over ever small intervals. 

We can use some maths to go further. By Green's theorem, assuming the fields are sufficiently smooth, we have

$\oint_{\partial A} E \cdot ds = \iint_A \nabla \times E \cdot dA$

So we can put

$\iint_A \nabla \times E \cdot dA = -\iint_A \frac{\partial B}{\partial t} \cdot dA$

which gives us immediately one of Maxwell's equations

$\nabla \times E = -\frac{\partial B}{\partial t}$

We can prove that, with the rest of Maxwell's equations, this another statement of Faraday's Law of Induction. 

This is no more conceptually complicated than if, having translated the passage of Freud, we then drew a conclusion from the translation and some background knowledge that was not in the original, but helps us understand what Freud was saying. It just looks impressive / mysterious / difficult because it uses undergraduate maths.

(ends)

My thesis is that translating from a natural language into math notation is the same as translating from one natural language to another. It's just that maths is the language in which it is easier to see the patterns and make the deductions.