Why I am reading my Electricity And Magnetism Text Book Again

As ever when I start one thing it leads to another. We Were taking a short break in North Norfolk and our host had built a personal philosophy based on his layman understanding of General Relativity and Quantum Physics.

General Relativity

This inspired me to look again at some of my physics which I studied at London University in the late 1960s. I remember that Special Relativity was mathematically easy but General Relativity was deemed to be much harder. According to the Times Reporter who covered Einstein’s lecture in London ‘there are only three people in the world who understood it’. I was told this by my lecturer in 1967 and assumed it to be true. However according to Simon Singh in his book The Big Bang Theory this was written by The Times Sports Reporter who was standing in for their Science Reporter who was on holiday. Oh, and he did not even go to the lecture but chose to spend the time in a London pub where he wrote his report.

Quantum Mechanics

Quantum Mechanics was taught in my final year as an undergraduate but had little appeal for me. I was and still am only capable of learning topics when I can follow a logical argument and in Physics this usually meant understanding the mathametical basis. I am no good at learning “parrot fashion” and found that when in exams I would always falter at the point I relied on just memory and not logic. For these reasons I quickly decided that in my endeavour for my Hon.s degree I would be better off skipping the Quantum Mechanis lecture and concentrating on other topics. The tactic was succesful in achieving my short term goal but unfortunate in the long term as Quantum Mechanics features heavily in present day science. Free of any need to pass exams and approaching 70 it is well past time I looked into this.

Special Theory of Relativity Postulates

Before delving into the details I thought I would read Why E=MC²? by Brian Cox & Jeff Foreshaw

which was a Christmas present yet to be read. I assumed it would be good overview of modern thinking but teach would me ittle new. I was wrong.

Einstein’s Special Relativity deals with Frames of Reference in constant motion whereas his General Theory includes Frames of Reference that can be accelerating. Einstein’s two postulates for Special Realtivity are :

1. There is no preffered frame of reference.
2. The velocity of light is the same in all frames of reference and independent of the velocity of its source.

There is no preffered frame of reference.

The first postulate is no great deal, already discussed way back by Galileo. Basically movement is relative to something which appears stationary. You drop a pen in a plane it lands at your feet but to an observer on the ground if he could have seen it it would have travelled in an arc. An observer on Mars whould see a more complicated path, and so on.

The velocity of light is the same in all frames of reference.

The second postulate for me was more surprising. Fire a missile capable of travelling a 100 mph from a plane which is travelling at 500 mph means that the missile will travel at 600 mph. If the missile is aimed at an approaching plane travelling towards you at 500 mph then the missile is travelling towards the target at 1100 mph.

Not so with light. Using a similar example as before, but this time the planes travel at half the speed of light c/2 and the weapon uses light. To the attacker the light travels away at c and not 3c/2. To the target the light also approaches as c and not 2c (c/2 + c +c/2).

This is hard to accept at first but from these simple postulates you can derive all the equations concerning the changes in time, length and mass with increased velocity and also E=mc².

I never understood how Einstein made this apparent leap concerning the independence of the speed of light but this was where Brian Cox and John Foreshaw book helps.

Maxwell’s Equations

Maxwell’s equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents. They were the culmination of the Electricity and Magnetism lectures.

I recall they express mathematically electro-magnateic waves that cover the whole spectrum from gamma rays, x-rays, ultra-violet, visible light, infra-red, micro-waves, short band, medium band etc. These various wavelengths all share the same speed, c and Cox and Foreshaw state that these equations show that c is a physical constant and independent of its frame of reference. Was this why Einstein specified his second postulate?

Anyway I enjoy this type of physics so I thought I would lok again at Electricity and Magnetism and being free of exams enjoy the exploration of the maths that accompany it. The text book I am reading is by W. J. Duffin published in 1965 (1st Edition), contemporary with my undergraduate days.

Michelson-Morley Experiment

At the end of the 19th Century shortly after the publication of Maxwell’s Equations the scientific world could not accept that light waves could travel througout the universe without a media to support it. They named this media ether and also hoped it would prove to be a preferred frame of reference.

Michelson-Morley performed an experiment to measure the earths movement through the ether in an elaborate version of the age old problem of swimming up and down stream of a river compared to swimming across and back. The stream was the earth’s orbit at opposite sides of it’s orbit and the swimmer was light. A brief description of this can be found at Michelson-Morley Experiment

The experiment revealed no effect at all and so the existance of ether was dismissed, and with it the hope of finding a preferred frame of reference.

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How History Was Beaten Into Me

School - Sharmans Cross

I started at Sharmans Cross High School For Boys in Shirley, Solihull in 1958, aged 11. Now do not get confused about it being called a High School, for in Solihull you needed to fail your 11+ to qualify, unlike Redditch High School which I went to when 16, where you needed to pass your 11+, but that is a different story.

Sharmans Cross had 950 boys and in my baby boom year there were 8 classes of 38 boys in each class. I was in the top class so goodness knows what it was like to be in the lower reaches.

History Lessons

In the four years I was at this school we had the same history teacher. His technique was simple, we were given a text book, told to read a chapter and towards the end of the hour lesson we would close our books and he would open his and ask us a series of questions. You were required to answer a minimum of 60% questions correctly in the first year when aged 11 to 12 an amount that increased by 5% each academic year. Fail to do this and you had to go to the front of the class to be slippered. This meant you bent down and touched your toes and then the teacher would hit your bum with one or two strokes with the sole of a large pump (plimsoll). Slippering was a lot less feared than the cane which was reserved for more serious misdemeanours although a few more sadistic teachers never bothered with the slipper but reached immediately for the cane.

Now I realise this is not a good or perhaps now even legal method of teaching but back in the late 50s and early 60s we never questioned it. We did however develop a tactic to reduce the chances of being hit.

The diagram above shows the layout of the classroom. Note the boy at Desk 28 balanced the history book on his knees beneath the desk. He got 100% every week. His answers were copied by the boys in his row and also the row behind. The answer was whispered to a boy in the row before 28 and so the answers were propagated around the class. The accuracy of these answers diminished as they travelled, similar to the game of Chinese Whispers so those further away would sometimes fail to meet the mark and be slippered.

I sat in the back row so escaped but the poor lad who sat at Desk 1 had no chance and I can see and hear the teacher even now saying "It's always you Youngblood" (not his real name, but close) as he bent over and touched his toes.

None of us thought of complaining, not that it would have done any good. The teacher was quite decent and never laid it on hard. He was probably bored with the lesson as much as we were and looked forward to his fag in the staff room whilst we looked forward to 20 minutes of mayhem in the playground.

The only time I can recall him beating me was when I tried to eat an apple. "Are you eating Tallis" he yelled. I swallowed the piece of apple and replied "Not now sir." He was not amused and I was summoned to the front and given a couple of blows.

The sad thing is I can only remember one thing from the 4 years he taught us and this was one of the rare occasions when he picked up chalk and wrote on the blackboard. It was about Charlemagne and the extent of his empire.

Change of School - Ridgeway

In the 4th year just after my 15th birthday we moved to a Worcestershire village which meant changing school. Ridgeway was much more rural orientated and only one third the size. The classes were smaller, about 30 in a class which made a bit of difference but the fact that half of them were girls made a big difference.

Mr. Lippet was our teacher and he could not have been more different. I believe he was a Baptist lay preacher, but I may be wrong on this. He controlled the class effortlessly, never spoke down to us and the thought of him beating any pupil was unimaginable. We were studying social history and I remember many small points of interest he talked about. For example he discussed with us why a man who works many hours of hard labour still works in his own garden afterwards, a mixture of necessity and the satisfaction of working for oneself he believed.

Eighteen months later I spent a day in glorious sunshine sitting on the flat roof of the local Observer Corp building on top of a hill just outside our village cramming history dates before tomorrow's O-level exam. Around me are Bredon Hill, Malvern Hills, Abberley Hill and in the distance the Clee Hills and beneath me swallows catch insects just above the grass.

It must have helped as I managed to pass the exam quite well with a grade 2, in those days grade 6 was the minimum pass level. This went towards the five passes I needed to qualify for a place in Redditch High School 6th form to study for A-level. At the time I did not realise going into the local grammar school was possible, it was only a chance remark by someone asking my father if I had started at the school that made us aware of the possibility. Dad made an appointment to see the headmaster and I started a week after the term had begun.

 

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Childhood Speech Impediment, Maybe?

I have already described two minor problems of my childhood, colour blindness and short sightedness, and now for the third and final problem, which was many people could not understand what I said.

My older brother said I did not talk until I was two, and since then I have never stopped.

No one in the family seemed to have any problems in understanding me, nor Ricky my pal from across the street who was just two and half weeks older than me. So all was well until I went to school.

I was quite keen to learn and shine at school when five years old and so was often the first to shoot up a hand to answer teacher's question. If the teacher chose me I would immediately give the answer and the teacher would then ask Ricky what had I said and he would tell her. Now the only problem to me was I had to wait a bit longer for the teacher's response, praise or correction.

Things must have been worse than I realised because suddenly I was being taken to a speech clinic on Friday afternoons. Now this did bother me, Friday afternoon at our school was play time, you were given access to a cupboard full of toys and you chose whatever you liked. I had to go with mum, catch the bus and go to this mysterious place in Solihull.The clinician decided the root of my problem were my tonsils and the solution was to have them cut out.

I remember a lot about my stay in the children's hospital. First night two of the bigger boys got us all to bang on our bedside cupboard and shout until we saw the door being opened and then to pretend to be asleep before the nurse walked into the ward.

The day of the operation I was put into a white shroud, a "tea-strainer" placed over my nose and mouth and told to count to ten. I managed to get to seven. But I also remember waking up in a "kitchen" lying on the "table" with people in white coats all around me. On went the "tea-strainer" again and I was told to breath in and out a couple of times. I woke up with a sore throat, but this meant I qualified for ice cream meals for the next 24 hours.

Afterwards I still had to go to the speech clinic but Solihull told us that there was a new one opened in Shirley which we now were to go to. So off we went a week later. I was handed a book and told to read what I could from the page. I can see the scene plainly today 63 years later. He said "Nothing wrong with you, you just talk too quick. No need to come again."

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I cannot recall any problems since with people misunderstanding me. Most of my working years were with IBM, first as a systems engineer and then a salesman, both involved giving countless talks and presentations and no one complained.

The closest was when I was in hall in the second year of university. Around the table were people from all around the country, Yorkshire, Geordies, Londoners, Welsh and others. I commented that I was the only one without an accent. I was quickly corrected and told that I had the strongest accent of all being a brumie.

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So of my three childhood problems, allthough problem is really too negative and strong a word, this one was false, short sight was corrected as a result of cataracts at an older age so only colour blindness remains. This is common in many people, especially males, so really I have nothing to complain about.

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School 1958 and my first caning!

I went to the senior school, Sharmans Cross, a large secondary modern school in Shirley Solihull in September 1958. To get to a secondary modern you had to fail your 11 plus which I did, but I soon got over the disappointment although remained jealous of my pal from across the street who not only passed but his parents rewarded him with a new bike with deraillure gears!

It was a large school with over 900 pupils, all boys and as I was a baby boomer the new first year was very large, with classes 1A1, 1A-Inter, 1A2, 1B1, 1B2, 1C, 1D, 1E, each with 38 boys. I was in 1A1. 

So how was this school run? Basically by the slipper and cane. The slipper was the sole of a size 10 plimsoll, or pump as it was called locally, and administered by any teacher for lesser misdemeanours in blows of 1 to 4 across the backside. For more serious offences the cane was used up to six of the best. 

Even before I went to the school I knew of this as my brother, 7 years older than me, had already experienced these. I vividly remember seeing him in the bath when he was 14 or so with big blue wheals across his behind. He had been in trouble over something or other and for punishment the teacher had told him to carry all the chairs and desks out of the classroom. 

"You must think I'm a bloody fool to expect me to do that!" and for saying this he was rewarded with six of the best. 

The same teacher was to teach me science later on and he had not mellowed much, but I will expand on this in a later post. 

Before my first day my brother told me that at some time a teacher would ask for volunteer to be caned and I should volunteer because afterwards I would never fear being caned again. 

In one of the early days 1A1 was in the Art Room. The Art Teacher walked up and down between the desks looking at our work. He carried his 1 meter long cane with him, on the top he had pushed a plastic Jiffy Lemon with which he use to "playfully" strike us over the head as the fancy took him.

In the front row a boy had dipped his brush into a colour at random and splodged it over his paper. 

"What do you call that?" shouted the teacher.

"I call it 'All Colours', sir."

Obviously not impressed by the abstract side of painting "Get out to the front" he barked "and bend over! "

He rotated the cane over so that the Jiffy Lemon was above his hand and gave the budding artist two swipes. 

"Anyone like to volunteer for the cane?"  he asked after the boy had sat down. 

Remembering my brother's advice my hand shot up, "Yes please sir" to everybody's astonishment, including myself, I called out. 

So he ordered me out and repeated the punishment on me. Well I immediately began to doubt the advise once I felt the pain but on balance I think it did remove the fear as there were many times I received the cane there after. 

Now this may all sound at best silly and at worse brutal, but it was a good school with great repartee between teachers and pupils, and if we took it too far then one or several or even the whole class would be slippered or caned and the balance restored. Anyway that was the view from the A1 stream, not sure how the C, D and E streams faired. 

Still I would not be happy now for the same treatment to be handed out to my grandchildren.