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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New Bike, Carbon Fibre and Rolls Royce

New Bike, Carbon Fibre and RR

Although my cycling experience and ability, and being aged 68, I could not justly forking out the cash for a new carbon frame bicycle I thought "To hell with it!" and a couple of weeks ago I took possession of a Ridley Fenix  complete with Ultegra Group Set (gears sprocket, brakes and levers). Ridley is small Belgium company. I bought it from a small specialist shop in Pershore called Echolon Where the staff are all keen cyclist and full of good advise.

Value and Price

You only have to watch TV programmes like Antiques Roadshow and Fake or Fortune to realise we all value things differently. I also believe that we instinctually search in others for similar beliefs and behaviour to reinforce our own and suspect, and sometimes get angry, with those that differ. We all can see on our news the effects of differing religious beliefs. I now make a conscious effort to accept that we are all different but essentially equal.

Some people enjoy spending their money on wine, cuisine, clothes, cruising, cars, watches, antiques, horses. None of these excite me but that does not make them wrong. I spend my pocket money on cameras, technology and now cycles.

My new bike cost approx. £1600. To a minority of people this will seem cheap, but to most it will appear extravagant. You can buy what the general public call racers new for less than £200 or you can spend £8000+ on standard design road bikes before you venture into tailor made bikes when prices can be higher.

The First Rides Experiences

Comfort

When researching which bike to buy all the shop assistants I spoke to claimed that I would find a carbon fibre frame and forks bike not only quicker but also more comfortable and easier to ride. This was certainly my experience when I cycled 28 miles around Bredon Hill. On my Trek aluminium framed hybrid bike I kept a keen look out for pot holes and drains to make sure I was out of the seat before being hit through the saddle. This is much less of an issue with the Ridley and increasingly I just remain seated.

Stability

The next thing noticed was how stable it was on the road. I had to make a quick serve to the left to avoid a car that decided to overtake a parked car as I as approaching. A quick jink and the bike was back into a straight direction in no time. I also found cornering much less scary when taken at speed.

Acceleration

This was a surprise. I do not race and my pleasure in cycling is just to be out in the countryside on my own. However there are times when you need to get out of the dangers of cars, say at traffic lights and even worse roundabouts. It is then when I realised how easy it was to accelerate clear. Also when flagging on a hill a quick burst out of the saddle will soon get the momentum up.

When buying the bike the guys at Echolon told me that weight was not the most important features of a bike, these were frame geometry and wheel weight. As they told me wheels act as fly-wheels which you have to get up to speed, hence the lighter they are the quicker they respond. I imagine this is an important factor in the improved acceleration.

My wheels are Fulcrum Racing 5 LG, which are a big improvement for me, but to put this in perspective I have compared prices for a wheel sets using the large online company Wiggle. My Fulcrum wheels are £165, Fulcrum top model wheels are £1,175 and the most expensive Wiggle sell are £2,475!

Group Set

The gears, brakes, sprockets and levers are Shimano Ultegra, only exceeded in the Shimano range by Dura Ace and I was expecting a real treat. They are the 2 x 11 gears, so the first advantage is when struggling up a hill I cannot mistakenly put the driving sprocket in the wrong direction so losing all my inertia, which I have often done on my other bike which has Shimano Deore gears in a 3 x 8 configuration.

In general the system works well, gears change smoothly, brakes work well but the one niggle I have is the gear change requires much large movement of the controls than on my much cheaper Deore system.

The gear levers are combined with the brake levers and have two parts, one the main brake lever itself which you move sideways towards the frame to change up to a bigger sprocket, and a smaller lever embedded into the back of the brake lever which you also move sideways towards the frame to change to a smaller sprocket.

Somethings I have learned about the system:

1. Big lever to change to bigger sprocket, small lever to change to smaller sprocket.

This means that when using big lever for the front driving cog you are changing up to a higher ratio (more speed more effort) and for the rear the reverse (less speed less effort).
The reverse is true when using the smaller lever.



2. The big lever for the rear has two very subtle clicks, the first after a shorter movement changes down one gear but if you continue moving the lever in a single action it will change down two gears. Good when you need to drop down suddenly as the hill is proving difficult to climb.
   
3. There is a mysterious trim movement on the front changers. My pal from Oz is visiting in the next few days, now he is a lifelong serious cyclist and I hope he will explain this to me, but in the meantime I discovered this advice on the web
   

Ultegra Front Derailleur Trim Options

Your 6800 front derailleur cage will start at the very bottom. (small lever clicked until the cage doesn't move anymore)
Now you swing your big lever up 1 click (actually a half-click) and the cage has moved from the small chain ring's "inner" most position to its "outer" most position.
Now swing your big lever up 1 full-click to jump up to the large chain ring. You are now in the large chain ring's "outer" most position. Click your small lever a light click (half-click) and you notice the chain did NOT jump down to the small chain ring. You are now in the "inner" most position of the large chain ring.
From here, when you do one full-click down on the small lever now, it will jump to the small chain ring and you will be in the "outer" most position of the small chain ring. One more small click and you are now back home to the "inner" most position of the small chain ring again.
All this to keep you from rubbing against the front derailer cage in either chain ring depending on which gears (mostly inner or mostly outer) you are in.

Rolls Royce and Carbon Fibre - 1968

My new bike is the first carbon fibre I have owned but I did see carbon fibre being produced at RR. I joined RR after graduating from London University in 1968 as a Graduate Trainee.

RR had just won the first ever major contract to supply a USA plane manufacturer of jet air liners, Lockheed Trident. To ensure that the American Congress did not veto the contract Lockheed emphasised that the main reason they chose RR was because the wonder material, carbon fibre, was being used to manufacture the very large fan blades on the RR RB211.

The material was made in what appeared to be a very large horizontal food mixer with black molasses looking mixture be stirred and then pulled out into threads. The whisk was about 2 meters square.

In the end the RB211 did not use carbon fibre and the fans were built in titanium. Anyway the real reason Lockheed chose RR was because it was the first large commercial triple shaft turbo-jet engine but this would be difficult to explain to Congress. I will make this the subject of a future blog.