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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Cycling - The early days.

Cycling - The early days.
I am prompted to write this "muse" having today just completed a 63.5 mile (101 km) ride around Bredon Hill and passing through Fladbury, Elmley Castle, Winchcombe, Tewkesbury and Pershore. A marvellous ride and I am pleased I can do this with little difficulty at the age of 68, albeit slowly.

Cropthorne

I am now more keen on cycling than any other period in my life although far less serious than many true cyclist. Where did it all begin?
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A predecessor was my scooter when I was 7 or so years old. It was not only my personal transport but also my pirate frigate, army tank and space rocket. But this did not last long and soon my elder brother taught me to ride.
"Don't let go." I called out to my brother who was steadying the bike by holding onto the saddle.
"I won't" he replies.
The question is repeated and the reply is the same until there is suddenly no answer and I am off alone wobbling down the croft. Next Dad finds me my first bike, not sure of the make but it is a standard type, black with solid rod brakes and no gears.
This bike was to serve me for the next few years. It's main purpose was to get me to and from school only a mile at max. It's other major task was to take me fishing, with my rods strapped to the top frame.
Of course once I was off to the senior school, 11+, I wanted a racing bike. At that age a racing bike meant one like my friends, one with drop handle bars. I now know that a racing bike has a lot more requirements such as frame angles, but then it just meant drop handles. So my Dad manage to conjure up a frame which he had shot blasted and sprayed blue and then added the wheels, brakes, chain set etc. Although I wanted that most mysterious component, dérailleur gears, Dad 'explained' that I would be much better off with a fixed gear.
A fixed gear is not only a single gear, but has no freewheel mechanism, so there are only two ways to stop pedalling, you either hold your legs clear and let the pedals spin around between them or you stand stiff legged on one pedal and bob up and down as the pedals rotate. The latter was quite spectacular and drew a lot of attention.
The bike was still a means to an end, to and from school, get me to my friends, fishing trips and the like. Favourite fishing locations were Earlswood Lakes and the Cut between the Grand Union and Stratford-Upon-Avon Canals at Lapworth, both about 5 miles from home.

Earlswood Lakes

I also cycled to Earlswood to watch the fascinating courtship of the Great Crested Grebes, an activity that has been shown on the nature programmes on TV a couple of times this year. I cycled there again this year, only now they are a 40 mile round trip. There are still plenty of Grebes to watch. I expected the Lakes to be smaller than my childhood memories but the opposite was the case and I was surprised how big they are.
I do recall one memorable trip when I was 14. My pal Chris was a member of the local church youth club which was having a night away in the Youth Hostel at Stow-in-the-Wold, about 45 miles away and he suggested that together with our school friend Doug we should go as there would be girls there. We three went to a school which had 900 boys, so the chance to actually meet girls was not to be spurned. The only problem was that Doug and I were members of the school rugby team and we had a match that Saturday so we would miss the coach. No problem we could cycle in the afternoon.
After the first three miles I realised I had left the map on the kitchen table, so as Chris had not played rugby he went back to retrieve it whilst Doug and I waited. The next thing I remember is at the entering Studley you passed a Gloster Javelin jet parked by the road side.
For some reason I have a vivid picture of the main road bending to the right and we had to go straight on down a narrow country lane. Perhaps the sight of this narrow lane stretching out into the houseless countryside made me realise we were getting a long way from the security of home and suburbia. I now live close to this place which is by Ragley Hall Alcester.
One of us had a puncture but then there were small cycle repair shops in the small towns and villages and we had it repaired.
We travelled on to Chipping Campden which even to a 14 year old boy was impressive. High ancient stone houses of the Tudor era. We needed refreshments and found a sweet shop. Although the buildings were tall the shop was small and the ceiling low. Chipping Campden is still worth a visit today and I prefer it to the more touristy Broadway.

Chipping Campden

Last leg now but it was dark and I am convinced a bat's wing pressed against my face and then peeled off again as we struggled over the Cotswold plateau. Still we got there to hot food and the pleasure of mixing with girls fulfilled.
At the age of 15 we moved from Shirley just south of Birmingham to a village in Worcestershire and the bike was needed more than ever as everything was at least four miles away. School was so far away we were provided with a coach to get there. So from a school with 900 boys I was suddenly in a school with just 300 or so, and half of them girls! But now the bike was used less and if we wanted to go anywhere we would hitch hike. I also began to dream of motorised transport and by 16 I had finally managed to get to the grammar school having scraped together enough O-levels to make the jump from secondary modern. Fed up with missing the school bus I soon acquired a motor bike and the bike was sold to a young pupil of the school who lived in our village.
It would be over twenty years until I started cycling again at the age of forty and this time cycling would become the prime aim and not just a means. Oh and the bike at long last would have dérailleur gears.

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