## Archive for September, 2014

### The days of our lives

September 30, 2014

Michael de Podesta is 20,000 days old today.

Today, 30th September 2014 is a special day: I am 54 years, 9 months and 2 days old!

Special? Yes, because today I am 20,000 days old!

It is natural to mark the passage of time since our birth.

Traditionally we do this by counting the number of times the Earth has orbited the Sun (years) since the day we were born.

We then celebrate when this number reaches a multiple of 10, the number of fingers and thumbs on our hands.

Is it any less arbitrary to count the number of rotations of the Earth about its axis (days) since we were born?

And then celebrate when this number reaches a multiple of 10. Or 100. Or 1000, Or in my advanced case, 10,000.

I don’t expect to see my 30,000th day on Earth (15th February 2042), but I am looking forward to 15th May 2023.

If I am alive, then sometime during that day I will pass my 2 billionth second on Earth! Wow!

On reflection, I realise it is arbitrary to pick any particular unit for counting our age – we should just follow the local convention.

But make sure that we celebrate every second of every minute of every hour of every day of every year. They all pass so quickly.

Happy Whatever 🙂

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You can plan the dates for your own celebrations using this excellent web site.

### Bent Hamer and the Kilogram

September 25, 2014

Tonight I find myself a thousand miles from home in a hotel in Espoo, on the outskirts of Helsinki. Outside it is raining and the temperature is just 10 °C.

I am here to discuss with colleagues from around Europe some of the minutiae associated with a new definition of the units of temperature: the kelvin and the degree Celsius.

You really don’t want to know the details: we worry about them so that you don’t have to. 🙂

And the day is auspicious. Thursday 25th September marks the 125th anniversary of the adoption of the kilogram as the international standard of mass. You can read NPL’s commentary on the anniversary here, And there is a new film release ‘about metrology’

The movie at the top of the page is a trailer for a film by Bent Hamer which appears to use the kilogram as a metaphor for… well I haven’t seen the movie yet.

But the mere existence of the movie does indicate that the ‘kilogram problem’ has entered popular culture – at least to some limited extent – and that is >fantastic<.

My wife and I have admired Bent Hamer’s previous films and sought them out at out-of-the-way cinemas. And we shall probably have to do the same with this one.

Bent Hamer’s films about IKEA researchers and retired railwaymen were not really about IKEA researchers or retired railwaymen. And I am sure this film is not really about the kilogram.

It is probably about the same thing that every other Bent Hamer film is about: the weirdness of other people’s ‘normal’ lives, and by implication, the weirdness of our own lives. And how important it is to nonetheless grab whatever happiness we can from the passing moments.

But I am filled with excitement at the prospect of this film. Parts of it are definitely shot at the International Bureau of Weights and Measures (BIPM) which is a thrill for us ‘insiders’ to see.

And he has certainly caught something of the obsessive personality disorder that  – if not actually required – tends to accompany an interest in metrology.

I suspect that Hamer’s fondness for humanity would probably lead him to sympathise with a statement such as

Man is measure of all things

And if I met him I would probably have to disagree.

The fact that I can type this article on a computer in Finland and have it appear on a server hosted in the United States, and be viewed wherever you are viewing this, rests on agreed measurement standards that are not amenable to different people’s opinions.

And the whole purpose of almost everything I do in my work – including this meeting – is to move beyond situations where correct answers are ‘a matter of opinion’.

But nonetheless, to see metrology dramatised in this way brings a smile to my face, and yields a frisson of simple pleasure.

I can’t wait for ‘1001 kelvin’.

### Lord Franklin should have waited

September 23, 2014

The first I knew of Lord Franklin was when I heard an old song sung by John Renbourn which told his sad story.

In 1845 Franklin sailed to ‘find a passage around the pole ‘ – the so called ‘North-West passage’ to the North of Canada, emerging through the Bering Straits into the Pacific.

But Franklin, along with his two well-stocked ships and 129 men disappeared, and no trace of them was found despite searches in subsequent years.

Recent research has established that his ships became frozen in ice and with his sailors he over-wintered on the ice. And then they slowly perished from cold and hunger.

And now, after all these yearsParks Canada have discovered one of his ships underwater in a state of near perfect preservation.

And they have released a haunting underwater video.

This part of the arctic is still inhospitable in winter, but the winter sea ice is not as thick or extensive as it was in Franklin’s day.

And in summer, it is now possible to take a cruise through the ‘legendary’ North West Passage.

And the sea ice is diminishing in extent and volume year by year. This year the summer melt of Arctic Sea (Charts here) ice is nearly over  and the trend is continuing.

Graph showing the extent of Arctic Sea Ice at its minimum area each September. The datum for 2014 is estimated as being the value on 18th September 2014.

So Franklin should have waited. And if his successor were to sail in  2045 rather than 1845, then they would likely find the North West passage to be more mercenary than ‘legendary’.

### I am still worried about student loans

September 20, 2014

By how much can one expect a salary to increase over 30 years? This is my salary for the last 26 years shown in raw numbers, and then adjusted for inflation into 2013 pounds. My inflation-adjusted salary peaked in 2009 a factor 1.71 higher than my salary in 1987.

Today I took my baby eldest son to University  and left him alone amongst a pack of wolves at his University flat.

A few people commented to me this week about my previous post concerning my son’s student debt.

My colleague Dave, for example, thought that I didn’t really need to worry, and that the apparent bonkers-ness of the loans was caused by a neglect of the effect of inflation.

I promised I would make some more calculations, and in between bouts of melancholy, I have made those calculations.

And I am still worried.

My Salary and Inflation

For a given amount of debt, there are three variables in this calculation:

• Starting Salary
• Interest Rate = 3% + RPI
• Rate of Increase of Salary.

So following Dave’s suggestion I set inflation = 0% which means the real interest rate is just 3%. That leaves just two variables .

I looked at my own salary to find out what might be a reasonable assumption for how much a salary might increase over the course of a career.

This data is shown in the graph at the head of the article. Taking the inflation-adjusted salary increase of a factor 1.7 over 26 years I calculate that this is equal to a 2.1% annual real increase. I think this is probably a larger increase than many people experience since I am (just) in the top 10% of the UK income distribution.

So now we just have one variable: starting salary. This can be compared with my own-inflation adjusted salary in 1987 (after my PhD and two years work) of around £30,000.

The graph below shows how starting salary affects debt repayment in this ‘no inflation’ , ‘realistic-salary’ model.

• If his starting salary is £25,000, then the debt is never repaid.
• If the starting salary is £30,000 – the inflation adjusted value of my own salary when I started working- then most of the debt would be unpaid.
• If the starting salary is £35,000 then the debt would be nearly repaid after 30 years.

The effect of starting salary on debt repayment. This assumes that my son’s income rises at the same inflation-adjusted rate that my income rose, 2.1%. If his starting salary is £25,000, then the debt is never repaid. If the starting salary is £30,000 (the equivalent of my own inlation-adjusted starting salary), then only a small amount of the debt would be repaid. If the starting salary is £35,000 then the debt is nearly repaid after 30 years.

So, assuming zero inflation and a year-on-year real rise in income like my own (~2.1% p.a.) the maximum repayable debt can be expressed in terms of starting salary.

Maximum Repayable Debt ≈ 2.35 x (Starting Salary) – £37,000

e.g. For a starting salary of £25,000, the maximum repayable debt is about £21,500.

This can also be expressed in terms of the minimum starting salary to repay a given debt within 30 years

Minimum starting salary = (Debt + £37,000) /2.35

e.g. For a debt of £50,000 the minimum starting salary that would ensure repayment within 30 years would be £37,000.

Of course this is the future – so  anything could happen. But these calculations further reinforce my view that I am right to be concerned.

Perhaps in 4 years time real starting salaries for engineers will have risen, but I somehow doubt it.

### I am worried about student loans

September 17, 2014

Simplified – and optimistic – projection for how my son’s salary might change through the years – and how his debt would change until it is written off after 30 years. Note that even with this above average salary, the capital on his student loan is never repaid.

My eldest son is off to University this weekend to study Civil Engineering. Overall this is a good thing, but I am worried.

It will cost my wife and myself a lot of money: we estimate  about £27,000 over four years – but somehow we will afford it. But that is not why am worried.

My son will acquire a big debt: we estimate that he will end up with a  student loan of over £50,000. But that is not why I am worried either!

So why am I worried? I am worried for you, dear reader, because the terms of the loan are bonkers.

What’s the deal?

The deal is that for each of his years in higher education my son can borrow £9,000 for fees plus £3,608 for support. So after 4 years he ends up owing £50,440.,

He begins to repay this when he earns over £21,000 a year – a figure which is currently intended to track increases in average wages.

For everything he earns over £21,000 the Inland Revenue will automatically take back 9%.

So if he earns £26,000 after he graduatesa good starting salary for a graduate engineer – then he will pay back 9% of £5000 or £450 per year.

Importantly, if his salary is lower than £21,000 he pays nothing, and although the debt increases as interest is added, his goods can’t be re-possessed to pay this debt.

And finally after 30 years – when my son would be roughly 52 – the debt will be written off.

This all seems pretty reasonable – effectively a graduate tax – and not really enough to discourage people from higher education.

What’s the problem?

The problem is that the interest on his £50,440 loan is (RPI + 3%). So if the Retail Prices Index is 2%, then the interest rate is 5%. And 5% of £50,440 is £2,522.

So in his first year of earning, his debt will increase by over £2000. He would only begin to pay off his loan if his starting salary was about £49,000! Only a tiny fraction of graduates will ever earn this kind of salary.

So under the terms of the loan, I can’t see how the majority of students – who in general earn less than engineers – will ever repay the capital on their ‘loan’.

And this means that far from being sustainable, the country – that is you dear reader – is taking on an additional £9 billion per year of unfunded debt which will never be repaid.

And that means a bailout at some point in the future and another national debt crisis. Or it means changing the terms of the loans in midstream.

I have ignored lots of things in these projections. For example, inflation, and the proposed increase in the £21,000 earnings threshold. However I think they still serve to indicate the magnitude of the problem – students earning realistic salaries after graduation will never re-pay their debt and create a sustainable fund to support higher education.

Below are graphs summarising a couple more scenarios – one rather optimistic and one more realistic. Please note that the scales on the graphs are all different.

Simplified – and realistic – projection for how my son’s salary might change through the years – and how his debt would change until it is written off after 30 years. Note the debt rises to £180,000 after 30 years.

Simplified – and highly optimistic – projection for how my son’s salary might change through the years – and how his debt would change until it is written off after 30 years. Note the debt is just paid off after 30 years.

P.S. Thanks to Dave and Jayne for putting me right on the terms of the loan. The best site available describing the terms is the Money Saving Expert guide.

### What do you do with an old nuclear reactor?

September 11, 2014

To search for additional amounts of radiation in the scrap from a nuclear power station you first need to screen out the normal level of radioactive background. To do this you must build a ‘chamber’ using special, non-radioactive bricks.

I find myself in the Hotel Opera, Prague this rainy Thursday evening, tired after having spent a fascinating day at the Czech Centre for Nuclear Research UJV Rez.

There I saw one outcome of a European collaboration (called MetroRWM) designed to answer just one of the difficult questions that arises when one needs to take apart an old nuclear power station. This is something Europe will need to become good at in the near future.

This didn’t concern the highly-radioactive parts of the power station: that’s another story.

This concerned the 99% of a nuclear power station which is no more radioactive than a normal power station.

What should happen is that this material should join the normal scrap system and be re-used.

However, the understandable surplus of precaution that surrounds nuclear matters will prevent this, unless every single bucket load of concrete or scrap metal can be verified to have a level of activity less than a specified standard.

The collaboration based at UJV Rez have built an apparatus to do just that. And most importantly, they have proved that it works i.e. that tiny hot-spots on the inside of pipes can be detected quickly and reliably.

Here is how it works.

To detect the tiny levels of radiation potentially coming from hidden radioactive particles, the apparatus uses ultra-sensitive radiation detectors.

However these detectors are useless if they are not shielded because our normal environment contains too much radioactive material. So the first step is to shield the detectors.

The low-background chamber at UJV Rez At the far end you can see a fork lift truck has just loaded a pallet which will travel through the chamber and emerge at this end. The doors at this end are currently closed.

The UJV team did this by building a ‘room’ using a special type of brick which is almost as good as lead at keeping out radiation, but much cheaper, much lighter, and much easier to work with. Using this they lowered the level of radiation inside to just 1% of the background radiation.

The two ultra-sensitive radiation detectors can be seen inside the shielded room as the doors open to allow the entry of test pallet.

They then built a system for loading pallets of material on a conveyor at one end, and drawing it through the shielded room to check the radioactivity in all parts of the pallet. The measurement took about 5 minutes, and after this the pallet emerged from the other end (Video below).

The key questions are:

• How do you ensure that ‘not detecting something’ means that there is none there?
• Could some activity slip through if it were shielded by some gravel, or steel piping?
• Could it slip through if it was in the bottom corner of the pallet?

To answer these questions the UJV team, in collaboration with scientists across Europe, created samples that simulated many of these possible scenarios.

Pallets of ‘radioactive’ waste. These pallets are a standard size, but there thickness is determined by the need to be sure any radioactivity trapped inside can be detected. The pallets above have been made very slightly more radioactive than the background.

One of their clever ways of testing the machine was to create samples of known radioactivity and place them inside hollow steel balls (actually petanque balls!).

A colleague showing a very low level sample of known activity which can be placed inside a hollow steel ball,simulating radiation trapped inside steel pipes.

The machine could then search for the activity when the balls were arranged in many different ways.

A pallet filled with steel balls, some of which have radioactive samples of known activity concealed inside.

The aim of all this effort is that at the end of the day, scrap material like that in the picture below can be rapidly screened on-site and sent to be recycled in the confidence that no hazard will ensue at any time in the future no matter how this material is treated.

The aim of the system is to screen very diverse scrap such these old pipes and ducts.

These measurements are not easy – but this work really impressed me.

### The hours of our days

September 8, 2014

The chart shows the number of hours between sunrise and sunset in London for each day of the year. In the spring and autumn day length changes by more than 3.5 minutes each day – or 25 minutes each week.

It is around this time of year that I begin to feel the nights closing in, encroaching on my evenings and generally making me feel that the summer is slipping away.

The change in the number of hours of daylight in the UK is dramatic, falling from a peak of over 16.5 hours to less than 8 hours. If it wasn’t so familiar we would be amazed.

At this time of year ‘day length’, the difference between sunrise (when the Sun just pops over the horizon) and sunset (when it just disappears from view) changes by more than 3.5 minutes each day – or 25 minutes each week.

But of course it does not get dark immediately after the the sun sets. Even when it is below the horizon the sun illuminates the sky which scatters light downwards giving rise to ‘twilight’.

Google poetically informs me that twilight is:

the soft glowing light from the sky when the sun is below the horizon, caused by the reflection of the sun’s rays from the atmosphere.

Wikipedia tells me there are three definitions of twilight based on how far the Sun is below the horizon.

• Civil‘ twilight is defined by the time that the Sun is less than 6º below the horizon.
• Wikipedia describes this as “the limit at which twilight illumination is sufficient, under clear weather conditions, for terrestrial objects to be clearly distinguished
• Nautical‘ twilight is defined by the time that the Sun is less than 12º below the horizon
• Wikipedia describes this as “when there is a visible horizon (at sea) for reference“.
• Astronomical‘ twilight is defined by the time that the Sun is less than 18º below the horizon.
• Wikipedia describes this as “when the dimmest stars ever visible to the naked eye become visible”.

The chart below shows the times of Sunrise, Sunset and the three twilight times compiled from data on this wonderful web site.

Graph showing the time of sunrise (red line) and sunset (blue line) for each day of the year. Also shown are times of ‘civil’. ‘nautical’ and ‘astronomical’ twilight.

This chart tells us what we already knew, that in the winter, not only is the day length shorter, but so is twilight.

In the chart above I have removed the anomaly of British Summer Time and so all the times shown are Greenwich Mean Time.

If we leave in this anomaly, then (looking only at sunset and sunrise) the effect of changing to British Summer Time can be seen below.

The time of sunrise (red line) and sunset (blue line) for each day of the year. The solid line shows the ‘clock’ time in the UK and has a jump when we switch to British Summer Time. The coloured dotted lines shows the ‘summer time’ in Greenwich Mean Time. The Black dotted lines 8:30 a.m. and 4:00 p.m. typical times for going to and coming from schools.

This shows that when we switch the clocks, instead of giving ourselves extra hours of daylight early in the morning, we choose to give ourselves an extra hour of daylight during summer evenings.

I think this makes sense. Alternatively, we could all just choose to get up a little earlier? Mmmmm.

### Care for a Danish-Style Shower?

September 1, 2014

Have you tried showering ‘Danish Style’?

A couple of weeks ago when I wrote about the continuing Californian drought, my friend Bernard Naylor commented that in many cultures people had adapted to a climate in which rainfall was scarce.

And he mentioned in particular ‘the Danish style’ of showering. He wrote:

Bermuda was settled by the British in the early 17th century. The island has no rivers or springs and is dependent entirely on rainfall. For hundreds of years, every building was required to be constructed over a cistern (to hold its water supply) and roofed so as to maximise water collection. People are encouraged to shower ‘in the Danish style’. That is,

• You wet yourself all over,
• then SWITCH OFF THE SHOWER.
• You then soap/wash yourself,
• and finally run the shower again to wash off the soap.

This struck a chord with me because I remembered reading that when Proctor and Gambol investigated the carbon footprint of their shower gels, they found that the carbon emissions arising from heating the water for the shower was massively more than the carbon footprint of the products themselves.

So over the last few weeks I have been giving Danish-style showering a try, and it is surprisingly pleasant.

• Firstly, the soap lathers much more easily than when the shower is continuously running and this is very pleasurable.
• Secondly, because the lather is so much thicker, I think I use less soap/gel than I did previously.
• Thirdly, I think I spend less time than I used to in the shower. The simple act of consciously switching off the water somehow interrupts the dreamy warmth of the showery idyll.
• And finally, I am saving a tiny amount money

My shower – which is typical of UK showers – uses about 7 litres of water per minute. (How do I know? I just measured it using a timer and a jug).

If the water is heated from 10 ºC to around 40 ºC (a hot shower) then pausing for just one minute saves approximately a quarter of kilowatt hour (882,000 joules) – which currently saves about a penny if the shower is gas powered, and between two and five times that much if the shower is electrically heated.

So this is a little thing that saves a little money and a little water. But it is actually quite pleasant.

Care to give it a go?

=================================

edaviesmeuk commented (below). How could I not have heard of this before!

• Also called a navy shower:

https://en.wikipedia.org/wiki/Navy_shower

Don’t do it where I’m staying at the moment as the “instant” LPG boiler takes a few seconds to light as the water’s turned on allowing a big slug of cold water into the system to surprise you after the warm which was in the pipes. Will make sure to arrange the plumbing on my new house to allow restarting the shower at the right temperature for just this reason.