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Nature of classical mechanics, (read with nature of quant mech)

December 6, 2010

Mohan, mdashf


I just wrote a few hours ago an essay which comprised of my ideas about the nature of quantum mechanics as I understand although they were in line with many of the arguments Stephen Hawking drew in his recent book Grand Design and Hawking in turn himself drew it heavily from Feynman Lectures on Physics.

Nevertheless as I mentioned in some of my articles Hawkings has many masterful examples to his account and almost 2 or 3 every page, if just a rough informal description is allowed. Most of the examples are innovative and draws heavily on the concepts as such.

I am not a fan of all the things Hawkings says (and who is, not even his wife), but he has his purpose and I have mine. He is more accomplished and I am more of a, here is a blooper. Not that I wouldn’t find something which I can not contest on Hawking, but that’s possibly not in the rule books of how we do science especially where criticism which is a fundamental basis of science, is meant to be too polite or politically correct.

Now since Hawking is something of a widely acclaimed scientist and rightly so as I just remarked above I am not trying to come out to be some kind of, all know it or know it all wart. But there are certain things that better be said if you think you must if you were to do any science let alone science of the highest kind.

And since Hawking is the best of all, he would be the least bothered by such criticism, its another matter this is presumed on the basis that he comes across this and says, YES !! Manmohan that’s exactly what I am thinking or proclaim, I do not disagree.

Apart from that I never personally interacted with him so I do not know what his characteristic humor towards me would be so that I can take that humor home and put it with a little whipped cream and say, what the hell let me take the creamed humor, howsoever I don’t like it. But beyond that it does not make any sense to dwell on this. My point is or should be clear that I don’t give two damn hiccups about what someone thinks of what I think. I have had enough of a Beaver weep.

I must mention I have six selling or best selling books of Hawking, what a tribute, if Hawking knows this I am his best friend in this sulky brain-smacking world. I would like to finish all of it with the interest of learning everything he has to say or hint about the physical world, but I can not at this point quite clearly proclaim that all the time I will give to this is worthy and as quality sensitive as I would do if I am on a paid sabbatical.

(Look at this guy…..do u need some more self humor, self bashing, I am unabashedly unrepentant when I smack anyone like that, don’t make it your chance)

But if I can not finish it all at that quality, I will form an ambition to finish this again, but by that time, I may even continue to many other books about our physical world, my library is just going to go on a Hubble expansion, I say, enough is enough, now read some of your own stuff.

So I have been trying to make a point clear, I am just trying to self teach me things that I have definitely come across myself. But with a little care this is all going much better than I have done it so far. Yes I am hinting towards my own book. I don’t know when it will be in print, but the first 10 copies will be free, to the first ten people I have a crush on, for being intellectually cute. (alright, that’s a promise, but I am a poor netizen)

OK!! I am not doing any good to my own topic here, so I better go back to what is the nature of classical mechanics. I have finished only two chapters so far of Grand Design (and one is Alternative Histories while the other is Theory of Everything) none of these two and none of the other chapters, I think, touches on the subject of nature of classical mechanics as a whole so I am not going to run any risk of soft plagiarism.

Humor apart the nature of classical mechanics is contrasted in this book against the nature of quantum mechanics and in many other books and in any usual discussions it’s pretty clear what the nature of classical mechanics is all about. Let me have my own say on it.

So let me be systematic on this article

1. What’s Classical Mechanics?

2. What is basic and central about classical mechanics?

3. What are its character vis a vis quantum mechanics

Let me be answerable to the above. But I don’t want to number my answer or responses. I want to go like I have always been going. First of all classical mechanics refers to the category of motions and laws of motion that constitute the everyday and not so everyday objects of reality. But as a rule it does not or can not qualify to describe the motion and interaction of objects and reality the size of which are so small that everything that classical mechanics tries to predict or describe about them are wrong.

So to make this clear by example lets take things by the scale. We have an atom, a wristwatch, a motorcar and planetary bodies such as earth and satellites. Now they all correspond to the most famous in their category and in their size, whoever says size does not matter is right. Except the atom, the laws of classical mechanics describes quite satisfactorily all the phenomena at the scale of the watch, car and the planet.

You may even go farther and say the objects of the size of our Galaxy are pretty well understood by the rules and laws of classical mechanics. Of course it’s not just mechanics but thermodynamics and theory of Relativity and the techniques of statistical principles that are involved here. There is more but this is just the basic idea.

And the idea that Relativity is included in classical mechanics is also like Heat and Thermodynamics and Electromagnetic phenomena are included in Classical Mechanics. What is not included clearly is what describes our understanding of the world of atoms and their kinds.

Except for the atoms everything else in some way or other comes into our daily way of forming a notion. The wrist watch is explainable by the working of springs and wheels, the motor car is driven by us directly so we know what it means when we say we hit the gas really hard and we bend forward, we speed up suddenly and we are dragged on our own, backwards.

We see how a moon is making a revolution on the top of our head through the same patch of sky everyday (albeit in a particular time of the year) and how the milky way looks from sky so if someone talks about its expansion through a pattern which matches that of the inflated balloon it all makes sense.

It also makes sense how magnets behave and their magnetic lines of force shows up on a set up, electric currents produce magnetic filed which in turn attracts or repels other magnets and irons in its close proximity. What does not make sense is how an atom behaves. (See my essay on the nature of quantum mechanics, the last one before this one)

So now its pretty clear what laws of classical mechanics would pertain to, how a barometer records pressure, how a bar pendulum can give us a value of the rate at which anything accelerates towards earth and so on, how a Lees apparatus gives us the thermal conductivity of a bad conductor or how Young’s modulus is measured by hanging weights on a copper string.

They all relate to simpler laws of nature such as an inverse square central force of nature or a few set of laws such as Newton’s various scheme of calculating the force or momentum and the equations of motion, that is, the equation that when solved gives us a well defined and definite answer for the value of any desirable physical parameter such as position and velocity of the object or a component of the system, given its initial conditions such as its initial configuration or initial speed and position etc.

Laws of classical mechanics also describe all sorts of wave phenomena, such as a sound or acoustic wave, an electromagnetic wave or a disturbance of electric and magnetic phenomena in various mediums.

As I have remarked above these laws are sufficient to describe with complete satisfaction any sort of physical and realistic phenomena we observe in nature starting from the scale of certain size of objects which excludes the pretty tiny of the kind of atoms and molecules their interaction and anything that constitute such tiny objects, the present day quarks, mesons, neutrinos etc.

eg such laws do not describe phantom creatures, vampires, Hada Bais (the bone lover, my nativity jargon for some sort of meta physical creature that loves human bones )

But these laws describe the functioning of the air conditioner in your room, how it works, employing conservations of energy and laws of thermodynamics, the functioning of electric motors, wheels and gears of a dynamo, the drag and lift of an airplane and the motion and trajectory of missiles and fighter jets, the propagation of waves such as the Radio and TV broad cast.

The most basic and central notion or conceptual underpinning as you may want to describe it is the definiteness or the so-called determinism. Given the initial conditions of a system the laws always allow reaching a prediction of its future and therefore all its past event histories.

Imagine this, if your plane reaches from Kansai Airport to Honolulu International via Chicago international airport then you can always backtrack in your memory all the events that happened, in reverse. Of course human memory as well as computer memory is limited and we are always constrained by many conditioned that are as natural as they are beyond our control.

Eg if we have a companion drone record our entire journey from Kansai airport in Osaka, of Honshu island in Japan to the HIA in Honolulu in Oahu, it may lose some of the path over a turbulent patch of air path and may not transmit all the data to the base station where we have our computers analyzing all data and reconstructing a reverse flying motion.

Despite of our conditions and constraints it’s quite clear conceptually that we can make a reverse event history of any process in Universe. Except a few ideas, which are, more of a complex nature and we only did a statistical or upper bound study we can think or even imagine most of the processes in nature to be reversible in nature. Even in case of a statistical sample where system parameters are more of an average nature we know what it means to talk about a reverse (event) history.

This has a strong contrast with the nature of quantum mechanics where in the last essay, The nature of quantum mechanics, I intended to talk about one experiment that Hawking actually described in his Chapter 4, on alternative histories of Grand Design. This is the so-called delayed choice experiment of John Archibald Wheeler, the PhD Guru of Richard Feynman.

Wheeler has been noted as the scientist who coined the term black hole.  Also he wrote a pretty famous book on Gravitation, the general theory of relativity. It all happens when you are a professor; you have to write something or other to keep your tenure. Humor apart the idea that he gave is pretty astounding.

He imagined  the Double slit experiment where the interference pattern is liable to disappear because we know by an additional arrangement which hole of the set up the bucky ball passed through. This they name as: which path condition. This is because the interference pattern does not make sense when you already know the path of the quantum wave particle. The observation of which path has interfered with the interference, if you like to see it that way.

But Wheeler comes up with a proposition to check to see how the radiation (photon or light emitted by a quasar) coming from a Galaxy far far away may show up an interference pattern in our projector or detector. (By the gravitational lensing of an intermediate galaxy)

Now this comes from a distance of a billion light years. If we can take our choice of delay right up to the point when the light rays have reached our place we can actually instruct these light rays to change their own event history so that the interference is amiss. This is really interesting. The history of an object of reality or reality itself exists in nature in a way it can change at any instant much into past the same way it can change much into future. (My Idea)

Also think of it this way (my idea again) this electron is actually permitted to create itself from a so-called pair creation process, so it may have a gamma parentage. A gamma ray gave birth to this electron. This gamma ray might have created itself from another electron or anther pion process or something. SO the pion might have come from one whole new process and so on and go back in event history to 1 billion years or if you are a fan of space more than time, to 1 billion light years.

So this 1 billion year has meant a tremendous amount of event history but at the base of this, is the tag, which slit the electron originally came from. If the electron can remember its original source point or even such a long chain of parentage then I think this is the most interesting facet of quantum Mechanics I have ever met. But Quantum Mechanics allows such a historical possibility because of its alternative history formulation.

But then the electron might just have formed right before we CHOICED our delay and this means every particle process occurs by sharing certain event history to the next or preceding particle in lineage. The gamma creates the electron and shares with it where it came from and where it is going to go. Hey, here is your space and time coordinates and your 4 momentum, now just go and add your phase and amplitude to know which path of history or future to take and don’t forget to share these information to the next particle in line.

The gamma also shares this with its pion father; the pion shares this with this gamma son and whoever produced the pion and so on. And this is all they have been doing since the unset of our Universe, but one thing to note is we don’t really need to affect the complete back chain of events of the most leading particle. By delaying our choice and by influencing the measurement in the process we just hit upon this particle and lost our interference scenario.

But tell me the truth, did I just invent how to solve the Wheeler paradox. One thing I realize while checking this back   though is that it’s a photon that Wheeler talked about, not an electron, but did the photon came all the way from the quasar a billion years ago and not for example produced a pair of electron and anti electron. In any case the argument that the event history must be shared among the particles in a particle physics process is something I feel like celebrating.  Time to go a little partysome.

Anyway this is what’s contrastingly different from classical mechanics. In classical mechanics there are a definite path not just a definite history. But we don’t change the past. Reversibility wasn’t known to classical mechanics either except for motion of objects where the complexity is not playing its silly games. If it reversed it was Newtonian, it wasn’t probably a statistical reversing. (Need more thoughts on this. And need to think more on this.)

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