Thursday, 3 December 2015

M346 Linear Statistical Modelling TMA01

So finished the first TMA01 for the linear statistical modelling course M346
This course is dull as dishwater but a necessary evil for me to complete my maths and statistics degree

The first question covered the usual stuff t tests, various distributions and chi squared and F tests and a bit of hypothesis testing.

All quite mind numbingly tedious you look up the formulae in Unit 1 and apply them

Question 2 covered how to use Gen Stat to test for normality and how to use the tools to calculate various probabilities

Question 3 covered linear regression the first a straightforward application of linear regression to a data set and the other requiring a transformation of the variables. You are taught how to interpret the linear regression output from GenStat

Really am going to die of boredom from this course but wont give up as I need the qualification

Not even sure what this is doing in a maths course as there are no derivations or proofs in the course

Got the tma back on Monday 4 marks short of distinction
lost marks on the transformation question as I didn't think of transforming the x variable and made a silly mistake in the linear regression question as I used the prediction of mean instead of future prediction. Still my tutor has provided a really useful summary of the correct answers

Probably heading for grade 2 if I don't die of boredom before I aim to do 1 questions from the TMA's per week, Might even finish the 2nd TMA over the Xmas holidays

Monday, 30 November 2015

So got the percentage mark for my Grade 6 theory result it was a respectable pass 72% but way short of a merit so glad to have passed but slightly disappointed the mark wasn't higher. I will know in 2 weeks just what the breakdown in marks was and round about the end of January ABRSM  will publish the 2014 papers along with the model answers. So I will be able to learn from the experience

Grade 7 next depending on how it goes I will try and do it in June but at least by November of Next year

Wednesday, 4 November 2015

Well yesterday I braved the gloomy Fog of Edinburgh and went to the darkest frontier of Sighthill to sit my grade 6 Music theory exam. I think it went reasonably well although there were one or two tricky bits. The exam consists of 5 sections and I had prepared myself by working through quite a few past papers upto 2014 over the past year or so. Also with the help of Victoria Williams my  music theory website and Udemy videos

http://www.mymusictheory.com/

https://www.udemy.com/u/vickywilliams/

A hint for those doing Udemy courses if you invest in one  then practically every week they will have course offers between £8 and £15 pounds. For grade 6 I did the Grade 6 melody course and the Figured bass course. Definitely worth investing in if you are contemplating doing the Grade 6 exam

So to the exam itself there are 5 questions

1 Given a melody can you work out an appropriate chord sequence or alternatively given the start of a melody with figured bass can you complete it.

I had got into the habit of doing the first question. To start with it is usual to start a melody with either an anacrusis leading onto the tonic chord or just usually the tonic chord so the first chord is either the tonic (Ia or ia) or if an anacrusis is used (Va-1a)

Usually the piece  ends with a perfect cadence (Va-Ia) if the melody ends with a descending scale figure ending on the tonic of the piece then it is possible to use the cadential 6-4 formula (Ic-Va-Ia)
So that is usually 3 or 4 chords that you can write down almost automatically.

The rest of the chords are worked out by first writing each possible chord that would fit (at this level there are only 3 that would work) and seeing if a logical sequence can be fitted in
For example if in the middle of the piece 3 notes form a descending scale passage leading to the tonic then a good fit is a sequence in the opposite direction ascending upwards

Suppose we have (in the key of C major) the notes E D C then in the bass we would have C D E and the chords would be Ia -viiob - Ib or vice versa if the melody was ascending

Then it is usually possible to find a sequence which follows part of the circle of 5th's progression namely

I-IV-vii-iii-vi-ii-V-I

So to some extent this question is a bit like a Sudoku puzzle you have certain clues and you have to fill in the rest of the grid. There are certain rules which one must follow, Never have the bass line or any of the other lines move in parallel fifths or parallel octaves with each other, So if the soprano line is G and you have chosen to use the tonic chord C if the next note in the soprano line is A do not make the note in the bass line D (a ii chord) One way to avoid this as far as possible is to ensure for the most part that the bass line moves in contrary motion to the soprano line.

Also never double the third of a major triad and a few other rules all explained brilliantly by Victoria Williams in her notes, sticking to these and learning a few basic chord progressions, usually gets you through. For this question you don't have to fill in the actual chords but just give the letters. One thing I find helpful in these exercises is to fill in the bass line making sure it doesn't give rise to parallel fifths or octaves with the Soprano line. If I were doing a full harmonisation I would always write the bass line first. Then fill in the other notes. One thing that is slightly odd about the ABRSM exam is that you can only label the chords by their letters or fill in the notes, So if you do leave the bass line in you will get marked down, So you end up rubbing out the bass line. A bit pointless in my opinion

The actual question worked out OK I think but I was a bit repetitive using far more Tonic and Dominant chords than I would normally expect to and also repeating the Ia-viib-Ib chord progression twice, I'll wait and see what the examiner thinks,

The second question was figured bass a topic which can be quite confusing but again explained brilliantly by Victoria in her notes and video. This is even more like a Sudoku puzzle in that the figures on the bass line tell the arranger or accompanist the type of chord to use, So example if there are no figures underneath the chord then the chord is in root position, If the note has a 6 below it is in first inversion and finally if it has 6-4 then it is in second inversion

Thus if the bass note were C with no figures under it would mean a chord of C major in root position C - E -G. If a figure of 6 were below it would be an A minor chord (A-C-E) in first inversion i.e with the note C as the bass note. Finally if 6-4 were the figures under the note then it would be the F major chord (FAC) in second inversion. Also there may be an accidental included. So the first thing to do is to work out which notes the figures are telling you to use. After this is done write out a soprano line which is interesting again trying for contrary motion with the bass line as much as possible and again making sure that the third of a major triad is not used.

Then comes a slightly trickier part filling in the Alto and tenor parts making sure that there are no parallel fifths or octaves between all 4 of the other parts. The only way to fully check this is to systematically work out the intervals between all the other parts. In the context of exam pressure this is really quite a tedious exercise to say the least. I generally trust to judgement and intuition hoping that provided I have no parallel fifths  or octaves between the Bass and Soprano lines no others will creep in. Generally speaking provided the alto and tenor parts just move to the nearest available note in the next chord then things should work out, But I have in my practice been known to let the odd parallel fifth creep in. I suspect the same would happen here. In order to make the Soprano part a bit more interesting then it is possible to fill in gaps with quavers so that suppose in the soprano part you had a descent from D to B then make the D a quaver and put in another quaver before the B.

The question was slightly odd in that there were quite a few quavers in the bass line needing a different chord. However provided I got the correct notes and didn't have to many parallel fifths or octaves then I should be OK (fingers crossed anyway)

The third question is to complete a melody of which the first few bars are given again Victoria explains how to go about doing this very well in her Grade 6 video. This often involves a modulation in the last few bars. If you plan out in advance the key points then it helps give a structure. Generally speaking a melody will have 8 - 10 bars and will move from the tonic chord to an imperfect cadence V on the 4th bar and then back to the tonic of either the same key if there is no modulation or to the new key. So again the first note of the 4th bar will be a note which fits the Vth of the given key and the last note will be the tonic of whatever key you have ended up with.

The examiner is looking for you to take what ever is given and use it again with some possible variations in rhythm. I generally try and sequence the second bar in the third bar by raising it up a tone and ensuring a movement by step to the dominant note in the first half of the 4th bar. Then using a logical sequence such as the circle of fifths to get to the modulation section usually with an inversion of the movement in the first phrase so if the first phrase has an ascending passage I will have a descending passage in the second phrase, If there is a large upwards movement then will have downwards leap and so forth finally if there is a modulation ending with a pivot chord from the old key to the new key and then V7-I in the new key. Where in the penultimate bar or half bar the notes of the new key are emphasised.

The question was a bit odd in that it involved a rapid scale like figure occupying 4 hemi-semi quavers and also a modulation from a minor key to the dominant of that minor key. Also despite being in 6/8 time the harmony of the second bar was static just oscillating about 1 note. The modulation caused me a bit of trouble but I managed to scrape something together hopefully it will be enough to get me through,

The last two questions are usually a bit more straightforward than the first 3 and I usually do them first to get them out of the way. They involve asking questions about 2 extracts of music the first one being a piece for piano or with piano and another instrument or voice. and the second a short orchestral extract.

In these questions you are generally asked to identify various chords and intervals the meaning  of certain terms such as Etwas Geschwind (Somewhat agitated, which I was before the exam), Also can you spot certain things such as a triad in first inversion and so forth.

The orchestral score question usually involves asking you transpose the music written out for horns in F or clarinets in Bb to how they would actually sound. If a horn in F plays what is notated as C it actually sounds like F so  you would transpose down a 5th,(7 semitones), Similarly for clarinets in Bb a notated C sounds like Bb  you transpose down a 2nd (2 semitones). So the easiest way to do this is to write out the notes of the chromatic scale of C major and underneath write out the notes of F major underneath it for horns in F or Bb for clarinets. Then write out explicitly the notes for each part as given and then under them the corresponding transposed notes. This can be a bit time consuming, also and I never got the hang of  this, if the original note has a flat attached do you transpose with the original note or with a sharp instead. Technically the notes would sound the same so Db is equivalent to C# but an interval with either C# or Db would have a different name. Thus Db - A is a 5th but C# - A is a 6th. As the interval questions on the orchestral score often involves one of the transposing instruments. It's not clear whether or not after you have made the correct transposition that you will get the correct interval

Anyway that was that I think I got most of the last two questions correct and hopefully will have done OK on the first 3. We'll just have to see. I await the examiners report with interest.

Next year provided everything went reasonably well I hope to do grade 7. For now upto Xmas I need to focus on my statistics course.

If you took the grade 6 exam or anyother grade theory exam I hope it went well for you as well

As a final comment it may seem to the average person that this approach takes the creativity out of music. However just as physicists or mathematicians can be creative within the context of a given framework (i,e the laws of physics or axioms of mathematics) so in music the laws of harmony provide a framework whereby some one can be creative. Of course if you are a Mozart or Beethoven then you can use the framework to construct quite different types of  pieces but the idea that is often floated that composers don't use the laws of harmony but just write whatever comes into their head is quite a misconception. They will usually have an idea of a melody either by picking notes out on a piano or something that they hear in their head, But those fragments will be developed into complete pieces only by following a given structure. I find it quite remarkable that provided you follow the basic laws of harmony and form you can write down a competent piece of music and that this craft can be taught.

Wednesday, 7 October 2015

A bit more on Bell

Some readers of the last post on Bell  may claim that I have missed the point. What my last account fails to do they would say is take into account the effect of the polarisation settings and the fact that they can be changed during the time of flight. So that as the usual story goes if the polarisation of the left detector is changed then the polarisation of the photon (or electron) will change in accordance with that polarisation but because the other photon must have opposite spin then it will change its polarisation accordingly.

I think from a statistical point of view this is misguided. A polariser acts as a filter and for a given polarisation angle only a fraction of the particles in the beam will be able to pass the polariser in a accordance with Malus's Law the probability of passing through the filter being proportional to the square of the cosine of the angle between the polariser setting and the photons polarisation angle. On emergence the photons that pass through the filter will have the polarisation of the polariser.

However some photons will not pass through. The polariser has destroyed any correlation there might have been with an EPR pair. Similarly at the other end a different number  of  photons will also pass through. The number of photons that pass through both ends being dependent on the polariser settings All this can be calculated from the basic laws of quantum physics. But given that polarisers will destroy any prior correlation. I can't see why it is inconsistent with the idea that before 1 or both of the photons hit the polarisers they were emitted from the source with perfect anti-correlation.

Clearly if one thinks the Bell State applies to single pairs alone then one would have to invoke some spooky action at a distance, But from a statistical point of view all we have is the probability of the photons electrons or whatever emerging through the polarisers.  One has to imagine the pairs being randomly emitted from the source with all sorts of polarisation angles, each pair being anti-correlated especially as the Bell state is rotationally invariant. However it is not clear, if one is just concerned with the overall transmission probability of photons through the polarisers which is all one can measure, that the photon that passes through the left polariser is one that is paired with the photon that passes through the right hand polariser. Because the polariser obviously destroys any correlation. Imagine if for example there was only 1 polariser say the left side then clearly the polarisation of the other photon would not change.

Given that in order to verify the statistics many events have to occur then there is no way of ever detecting a single pair of photons.

On that basis then I still feel justified in denying the need for any form of super-luminal signalling between a single pair of photons.

Monday, 5 October 2015

Long term plans

So my (current) long term plans are as follows

2015 - 2016  M346 Linear Statistical Modelling
2016 - 2017 M347 Mathematical Statistics and possibly M140

So hopefully I will then have a BSc in Maths and Statistics

Then I shall build on what I have already to convert this to a Maths and Economics degree
For which I will need the 2 economics courses
2017 -2018       DD209 Running the economy
2018-2019        DD309 Doing Economics People Markets and Policy

and also the Maths Methods course MST224 which I would do alongside DD209 probably

Then having got the economics courses under my belt I could go on to do the Politics Philosophy and Economics degree by doing the 2nd level politics course,

2019-2020      DD211 Understanding politics: ideas and institutions in the modern world

Then a third level politics course and finally the third level philosophy course. So that would complete 3 Open university degrees within the next 7 years or so.

Concurrently I would be continuing with my music studies Grade 6 theory beckons in a months time
Grade 8. Also by the middle of next year  I would hope (money permitting to embark on the Open College of Arts composition course with the aim of writing an extended piece of music within the next 5 years or so.

http://www.oca.ac.uk/courses/music-courses/

So that should keep me busy for a while.

Saturday, 26 September 2015

The Bell State a defence of naivety

In this post  I wish to defend a naive interpretation of the Bell State against some of the more wilder claims made for it in the literature

The Bell state (for those who have been asleep for the past 40 years) applies to a pair of particles emitted from a common source in opposite directions. The Bell State describes the joint spin of the two particles which because of the conservation of angular momentum must be zero. But until measurement occurs we do not know the spin of a given  particle so the probability amplitude takes the form

$$|B> = \frac{1}{\sqrt{2}}(|u1>|d2>-|u2> |d1>)$$

where u represents spin up and d represents spin down and the naive interpretation I want to defend is that this simply represents the conservation of angular momentum, so that once the spin of 1 particle is known by measurement, then the other spin is automatically known and must be equal and opposite. All the Bell state represents is the 50 % probability on measurement that the particle a person observes at one detector will either be measured with spin up or spin down. Repeated measurements will confirm the fact that at a particular detector the spin will be measured up or down 50% of the time and at the other detector the spin will be equal and opposite. It is well known that the Bell state is rotationally invariant so if one the particles are emitted at an angle $$\theta$$ with respect to the polarisation axis between the particles, the other particle will be emitted at an angle $$-\theta$$ with respect to the polarisation axis . Applying a bit of Pauli spin algebra to the Bell state is well known to give the correct correlation function as was spectacularly confirmed by Aspect in the early 1980's

So why all the fuss, apart from the intrinsic skill in being able to measure the relative spin states of two particles separated a long distance away, from the naive perspective I am offering this is just another routine success of quantum mechanics.

As many people will know, the fuss has arisen because it is claimed that this experiment encapsulates the essence of the debate that Bohr and Einstein had in the early 1930's about the interpretation of quantum mechanics and which culminated in the so called EPR paradox.

To cut a long story short the claim is made that because we don't know the spin state of a given particle before measurement, The Bell state represents a physical state of superposition so that the particles spin state is undetermined until measurement which then collapses the Bell state into one of the two possibilities. So that it is claimed the other particle instantly knows what spin take to take as soon as the first particles spin state has been determined. As the particles can in principle be millions of miles away, it is claimed that this means that some signal faster than the speed of light has been sent to the other particle. Thus there would appear to be a prima facia contradiction between special relativity and quantum mechanics.

Furthermore in his paper

It is claimed that Bell showed that the 2 assumptions

a) that there were hidden variables that predetermined the spins of the particles

b) the assumption that the two detectors were independent of each other

Led to a contradiction with the predictions of quantum mechanics.

The failure of assumption a) would imply that quantum measurements cause reality to happen giving rise to the 'California Interpretation' and the failure of assumption b) gives rise to the idea  that a measurement of the spin of a particle at one detector affects the other. This is the so called 'Spooky action at a distance' On this reading (which is the one that seems to pervade the popular literature) The Aspect experiment would imply that quantum mechanics does either involve spooky action at a distance (non-locality)  or a form of non realism in which measurement determines properties of particles. What is worse in the popular literature, both claims are made about quantum mechanics when it is clear that only one of the two need be made. So that ever since the Aspect experiment quantum mechanics is seen in many circles  as being both non-realist and non-local.

I want to challenge not the assumptions that Bell made but the interpretation of their significance as they have become known in the popular literature.

First it should be stressed that Bell himself did not think quantum mechanics in itself showed non-locality or spooky action at a distance. If one reads the conclusion ( section VI) Bell states explicitly in the first sentence.

In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements without changing the statistical predictions, there must be a mechanism whereby the setting of one measuring device can influence the reading of another instrument, however remote. Moreover the signal must propagate instantaneously, so that such a theory could not be Lorentz invariant.

So what Bell thought he had proven was that hidden variable theories had to have some form of non-locality or spooky action at a distance not quantum mechanics. Indeed if one goes through the actual calculation of the correlation function measured in the Aspect experiment using quantum mechanics no mention is made of any form of signalling at all. All one does is apply a bit of Pauli Algebra to the Bell state and out pops the result almost by magic. It seems odd to claim non-local signalling to explain an experimental result when the correct quantum mechanical prediction makes no mention of it.

Lets consider the situation in a bit more detail

Quantum mechanics is essentially a statistical theory, the solution of Schrodinger's equation for a given problem gives rise to a probability amplitude the modulus squared of which gives rise to a probability density function via the Born rule. The solution to Schrodinger's equation is not a real wave existing in (3N+1)*S configuration space where N is the number of particles and S is the product of all the possible spin states of the particles involved. But effectively the square root of a probability density function and the (3N+1)*S configuration space is simply the probability sample space not a real physical space.

That being so the Bell state is nothing physical it is (as is any quantum superposition) a superposition of possible outcomes with coefficients representing the probability of one of the possible outcomes. When a measurement is made the so called collapse of the probability state vector is not a physical process, but a realization of one of the possibilities, just as say I can assign a probability state vector to a coin or a dice or any situation which results in a number of possible outcomes N

This is simply

$$|Final> =\frac{1}{\sqrt{N}}{a_1|1a_>+.........a_n|N>}$$

where the a's represent the square roots of the probability of one of the outcomes being realized.

But the system, is not before measurement physically in some hybrid state of all the possibilities. All one can say is that one of the possibilities will be realized on measurement, not that measurement causes the system to jump from it's limbo state into one of the possible outcomes. The probability amplitude can be seen as akin to a Bayesian prior representing our best guess as to what the possible outcomes will be. Given that one can by definition only ever see a quantum system in one state speculation as to what happens before the act of measurement occurs is totally meaningless.

Furthermore if as the standard story has it the spin states of the particles are only determined at measurement then that would make a nonsense of the conservation of angular momentum. It would imply that the conservation of angular momentum only applies at the point of measurement. On the naive view I'm defending the relative orientations of the particles spin states is fixed at the point of emission but we wont know what spin state we will measure at a given detector. So whilst a given individual particles spin state is not determined, the relative orientation with respect to the other is, If that is not so then the conservation of angular momentum is meaningless and we would not be able to predict the outcome of experiments such as those at CERN. I hope then to have dispelled the myth that the Aspect experiment or any other such experiment involves spooky action at a distance.

Ok so what does entanglement or non-locality actually mean?  Again there is a fairly straightforward interpretation. If the joint probability state vector of a system of many objects is entangled that means that it cannot be written as the product of the individual objects probability state vectors. This is well known in statistics, If the probability density function of two or more variables cannot be written as the product of the probability density functions of the individual variables, then that is is an indication that the two variables are not independent of each other. For the Bell state we know that the individual particle spin states are not independent of each other, as they are equal and opposite because of the law of conservation of angular momentum. Again there is no need to invoke spooky action at a distance and I have to say Bell has misled a whole generation of physicists by invoking this in his conclusion.

Is my interpretation consistent with the quantum formalism undoubtedly yes as I am using the Bell state to make the correct predictions as measured in the Aspect experiment. The question has to be why invoke spooky action at a distance or collapse of the wave packet when a simple statistical interpretation in accordance with the Born interpretation is all one needs to successfully predict the outcome of quantum mechanical experiments.

As a final point if Bell has really disproved the existence of hidden variables then we cannot go beyond the statistics to find out "what is really going on". The hope of going beyond the statistical predictions of quantum mechanics to predict the results of individual measurements is an illusion and "Nature really does play dice."

"

Friday, 18 September 2015

Yet another episode in the quantum madness game

This time the claim is the rather somewhat ludicrous claim that a microbe before it's position is measured is in two places at once.

This really is such  gibberish that it is hardly worth bothering with. But at the heart of it lies a misunderstanding of the nature of quantum superposition

The claim is that a quantum superposition is real so that particles really can be in two places at once until measured in which case the 'position wavfunction' collapses into one of the two positions.

Of course the more pragmatic point of view would see quantum superposition as a superposition of possibilities with a given probability of the object being in one position after measurement.

The latter interpretation is much more sensible and still consistent with the formalism of quantum mechanics. I really do despair why such a view isn't propagated more widely.

I don't understand the need to see quantum mechanics as something mysterious or weird has taken hold on so many people.

One can only sympathise with David Hume when he says regarding the tendency of rationalist philosophers to overstate their case

"Though the chain of arguments which conduct us to it were ever so logical, there must arise a strong suspicion …that it has carried us quite beyond the reach of our faculties when it leads us to conclusions, so extraordinary, and so remote from common life and experience, We are got into fairy land.  (An Enquiry Concerning Human Undestanding VII ) .

Friday, 28 August 2015

Two Songs

Here are two songs that I have set to poems written by my girlfriend Angela

The first comfort me  was written just after I completed A224, The lyrics are as follows

Lullaby  by Angela Brown

Sing me a lullaby as I drift to sleep
Hold me so close, whilst my dreams secrets keep.
Lie still beside me, feel the bond that's deep.
Sing me a lullaby as I drift to sleep.

Whisper how precious worlds that collided  now reap.
Kiss me so gently  for I dare not weep.
Sing me a lullaby as I drift to sleep.

Tell me your sorrows for I am not weak.
Trust in a future we both dare to seek.
Sing me a lullaby, as I drift to sleep.

The Scorch file is here and for those who don't want to download Scorch I've included the midi file.

https://dl.dropboxusercontent.com/u/16049029/comfort_me_final.htm

Midi File

https://dl.dropboxusercontent.com/u/16049029/comfort_me_final.mid

Musically the accompaniment is based on a figure from Bach's C Major Prelude. The song starts in   Eb major and by the end of the first phrase has modulated to Bb major. For the second verse a musical interlude faciliates the moduluation to C minor and then for the final verse the song finds its way back to Eb major. A iib-V7-I cadence in Eb major finishes the song off. For those who managed to down load the Scorch file the roman numerals under the Bass clef give the chords.
Each phrase more or less follows the Harmonic Scheme I -  - ii vi - IV -V -1 and modulation is effected by pivot chords usually     vi - ii for the modulation from Eb major to Bb major and for the transition to the minor key

The second one Angel Man went through a number of iterations and was finally completed earlier this week. Angela envisages some one who is troubled when an Angel visits them whilst he\she is walking through a garden or park  giving them reassurance that things will work out ok

An  Angel Man by Angela Brown

Let's take a walk he said to me
Through a garden filled with love
This journey is from me to you
I will give you knowledge rare
Inner peace and blessings true
Gifts for in abundance for you to share
He kissed me gently and said it is done
For your work now has just begun.

The accompaniment is that of a stride (appropriate for a walk) and I have used what might be called the magic formula of music, namely the circle of 5ths harmonic progression. That is each chord  follows the harmonic scheme I-IV-vii-III-vi-ii-V-I, with two chords to a bar.

The song starts in D major modulates to A major then to B minor and back to D major again using pivot chords.

One thing that is quite remarkable is how following a basic chord progression enables pieces of music to be created quite easily. Almost algorithmic in fact.

The Scorch file is here

https://dl.dropboxusercontent.com/u/16049029/NewAngelMan6c.htm

and the midi file is here

https://dl.dropboxusercontent.com/u/16049029/NewAngelMan6c.mid

I hope you enjoy both the words and music

Tuesday, 18 August 2015

Test scorch link 2 Minuet in C

This is a little minuet I composed (constructed) a while back

https://dl.dropboxusercontent.com/u/16049029/MinuetinC.htm

Hope you enjoy it I'll publish the recipe for constructing a minuet on another post

This won't work if you are trying to access it from Google Chrome use internet explorer instead

Best wishes Chris

Monday, 3 August 2015

M303 Alternative (And free)

I have been asked my opinions about M303 the new pure maths course which started last year. Given my car crash with the old topology course which I just scraped a pass at, and my dropping out of M381 I have to say my experience of pure maths at the OU has not been a particularly happy one. Looking at the fora it would seem that M303 has had a number of people criticise it. I suspect part of it is the intrinsic nature of pure maths which really does require quite a different mind set to some one like me who likes the calculational side of things and not the endless forest of definition, lemma, proof that seems to be part of pure maths. However M303 does seem to give some one like me a second bite of the cherry. But I can't see me doing it. It would be 60 points of relentless slog. On the other hand it would be nice to learn about rings fields etc and the more advanced parts of group theory such as the Sylow theorems.

There is in fact an alternative supplied by Saylor Academy

https://legacy.saylor.org/

which has a number of maths courses free of charge. Unfortunately Saylor have changed their support for a lot of courses and the maths courses have been moved to legacy which means that Saylor will no longer give exams on these topics, Nevertheless if one wants a structured guide to maths at undergraduate level then this would appear to provide an alternative.

The maths options

MA231 Abstract Algebra I

https://legacy.saylor.org/ma231/Intro/

MA231 Abstract Algebra II

https://legacy.saylor.org/ma232/Intro/

would appear to cover the algebra and group theory topics of M303 if not more as the two courses go up to Galois theory.

The main text is Judson

But there are links to you tube lectures and other goodies.

Obviously doing this wont give you a real qualification but as it's free and structured, you wont be overwhelmed with having to do all the exercises. At 4 - 5 hours per week it should be possible to do these two courses in a year.

Anyway I have started hopefully I will finish

Saturday, 1 August 2015

Normalisation of relativistic wave functions. Is the Born interpretation viable in relativistic quantum mechanics ?

I have just been reminding myself about relativistic particle physics with the help of these wonderful lecture notes given to 4th year undergraduates (MSc level) at Cambridge university (scroll down)

http://www.hep.phy.cam.ac.uk/~thomson/partIIIparticles/

Anyway a point of significance which is normally skated over, is that in relativistic quantum mechanics, the wavefunctions (solutions to either the Klein Gordan equation or the Dirac equation ) are normalised such that the Integral of the modulus squared of the wave function over a volume is eqaul to 2E where E is the energy of the particle, This is in contrast to the case in non relativistic quantum mechanics where the integral of the modulus squared of the wave function is put equal to 1 ie for Non relativistic quantum mechanics we have

$$\int \psi^*\psi dV = 1$$ but in relativistic quantum mechanics we have

$$\int \psi^*\psi dV = 2E$$

The reason for this normalisation is that in relativity volumes contract in proportion to the energy of the particle and the factor of 2 is conventional. In non relativistuc quantum mechanics the normalisation effectively means that there is 1 particle per unit volume. Whereas in relativistic quantum mechanics there are now 2E particles per unit volume.

In non relativistic quantum mechanics the normalisation to unity, leads to the Born interpretation and despite all the hoo hah in the popular literature about how quantum mechanics is not understandable, The so called wave function (solution to Schrodinger's equation) has a fairly simple interpretation as effectively the square root of a probability density function, albeit in order to account for quantum phenomenon this square root of the probability density function is often a complex function and not a real one.

However given that probabilities are constant and not functions of energy, the direct link between the solution to Schrodinger's equation and a probability density function is no longer there in relativistic quantum mechanics, Those who spend all their time trying to understand the 'meaning' of the wave function in quantum mechanics are going to have change their understanding when it comes to relativistic quantum mechanics.

There is a solution in terms of particle currents which I will post a subsequent blog on but I do find it surprising given all the hoo hah there is about the interpretation of quantum mechanics and focusing on the solution to Schrodinger's equation that this difference hasn't been emphasised at all, At least superficially it would mean that the Born interpretation is no longer applicable to relativistic quantum mechanics,

Wednesday, 22 July 2015

Hi this is a test of a scorch link
http://www.tonybloomfield.pwp.blueyonder.co.uk/kevock/

Scorch is an Application which enables posting of Sibelius Files to be accessed by anyone. If you want to hear the piece then simply click on tthe link and if you haven't already installed Scorch then you will be invited to do so. It's free a word of warning though if you are using Google Chrome as your browser then it wont let you access it as for whatever reason best known to them. Google Chrome has decided to not support Java Applications any more. So use Internet Explorer or firefox.

Anyway hopefully I'll be able to post some of my own pieces here soon.

Sunday, 26 April 2015

M346 Linear Statistical Modelling

Well after two years absence from the OU I have decided to complete my BSc in Mathematics and Statistics under the old regulations I need to do two 3rd level statistics modules namely M346 Linear Statistical modelling and M347 Mathematical Statisitics and these need to be completed by 2017.

As I'm busy with other things namely music theory and piano and also my own studies I feel it best to do one module at a time. So will do M346 first and then M347. I did start M346 a while back but it got in the way of other OU courses and to be quite frank I wasn't all that impressed with it to say the least. soo I abandoned it

Maybe I will find it better 2nd time around however it is a necessary step for a named degree so I shall treat it a bit more seriously than I did last time

Apologies for not posting for a while.My immediate focus is on grade 6 music theory and I shall be sitting the exam on June 20th. Then start preparing for Grade 2 piano in November.

As far as maths is concerned I have been working through the Cambridge Mathematical methods example sheet on Fourier Series

http://www.damtp.cam.ac.uk/user/examples/

The first half of Sheet 8a

The last problem has imtroduced me to a phenomenon which I haven't come across before called the Gibbs phenomenon. Namely that near a discontinuity such as those found in a square wave there will always be an overshoot or undershoot in the Fourier Series no matter how many terms in the series are taken. When I have written up the problem I'll describe it in more detail in my next post.