28 March 2011

Weird Science As Explained To Emmy The Dog

Weird Science As Explained To Emmy The Dog

I have been reading “How to Teach Quantum Physics to your Dog” by Chad Orzel, because I love reading about quantum physics, relativity and the creation of universe, partly as I am a geek and also as I do not understand what is going on at all and reckon that sooner or later I will get there and I will have a Eureka moment.  This book is really quite light hearted, yet tackles many of the core underlying themes in modern physics, e.g. wave particle duality, Heisenberg’s Uncertainty Principle, Schrödinger’s Cat and the Quantum-Zeno Effect.  It is built off the back of his amazing blog - http://scienceblogs.com/principles/.

So while Chad was banging on about Heisenberg, he wrote:

"You can make the momentum change smaller by increasing the wavelength of the light (decreasing the momentum that the photon has available to give to the electron), but when you increase the wavelength, you decrease the resolution of the microscope, and lose information about the position.  If you want to know the position well, you need to use light with a short wavelength, which has a lot of momentum, and changes the electron's momentum by a large amount.  You can't determine the position precisely without losing information about the momentum, and vice versa." [p48 from Chad Orzel's book]

It was then that I had one of those small moments of understanding where I felt that physics teachers have been deliberately misleading me, obfuscating and confusing me and making it all seem harder than it really is: wave-particle duality does not mean that light, matter etc is two things at once, which is how they explain it.  Rather this idea of duality is simply artifice to explain light’s properties mathematically and physically, i.e. a model to explain the behaviour of things in the universe.  Light is light, matter is matter, the lamp post outside my window is a real physical object and the sycamore on the green lives and so on.  However, the physics and so maths needed to explain the properties of these objects and how electrons and light work needs more than one theme to get it all sorted out.  So measurable stuff comprises a physical form (the particle bit) and energy (the wave bit), and we need both bits to sense things.  By the way, both of these are relative to other things, so it is really relative physicality and relative energy, hence I cannot feel something that is too small for me to sense.

This raises an interesting thought, being what happens if you have energyless particles and particleless energy.  Now modern physics says that even the lowest energy particles have velocity and so you cannot get a no-energy state.  But what if you can decouple energy and physicality?  If you could get these “things”, then you would not be able to measure them and so they become voids or “dark”.  Is this what dark energy and dark matter are? Formless energy and energyless form.  Humanity is not coded to be able to sense these, or even really to understand such things.  But what happens if that is what these missing bits are, i.e. 23% for dark matter and a whopping 72% for dark energy of mass-density of universe? Could you actually measure them rather than infer them - the only way to measure these two missing parts of the universe would be to give them back what they have lost, i.e. give energy to dark matter and form to dark energy, but would that actually be possible, or even for that matter a good thing.

Thinking about it why shouldn't there be energy without a physical side and matter without an energy side.  Yes that's not what we see/measure, but these are things you cannot measure or see, so why not?  In fact, it makes physical things more unique and basically says that there is something special about "normal" matter and energy as these are things where matter and energy are linked together rather than separated.  It is quite easy to envisage energy without shape as that is simply energy, i.e. just a wave and no particle bit, however how do you have matter that you cannot see as wouldn't we just bump into it as we try and measure things.  Perhaps dark matter is shape than has folded in on itself until it is so infinitesimally small that you just cannot measure it and that there is something about adding energy that enables pre-matter to unfold and become detectable.  But now I am really lost in my own explanation.

Another thing that Chad Orzel writes about is why quantum mechanics does not work in the real world very often and that systems collapse into old-fashioned Newtonian mechanics.  This is one of the reasons most of us simple punters find quantum physics so complex as it does not marry up with our experience of the physical world, even if the maths works and so has allowed loads of new discoveries.  The theories, or philosophies, as to how the quantum world collapses when things are measured/observed includes theories like the Copenhagen Interpretation, Everett’s Many Worlds Ideas and Feynman’s Shut Up and Calculate Concept [actually not Feynman but David Mermin, but he's way less iconic].

I feel all these are too complex and perhaps too overthought and overwrought, i.e. everyone is simply trying to hard.  I think it is really just a matter of scale, so quantum theory works fine at a small level where there are very few components to a system.  However, as you scale up, you just need a new way of looking at things.  Nothing has changed with quantum physics as it still works at a micro level, but it just does not work on larger scales.  Different things need different ways of looking at it.

However, should you still want a mechanism for why it changes, here goes.  Everything can be described by a wave pattern using Schrödinger's rules.  These are all different shapes and sizes, but everything big and everything small has a wave that describes them.  At a small scale where there are not many things about and the gaps between everything are relatively large, these waves have the space to take shape and grow to their full size, hence the properties of that wave become paramount in their behaviour.  So at this small scale and with little noise from other stuff kicking about, quantum physics and all those ideas work.  However, as you scale up, other waves start getting in the way, interfering with each other, changing the shapes of the waves, filling up the space with other waves and so preventing them fully expressing themselves.  In effect, quantum waves interfere with other quantum waves and they reduce their influence on their behaviour, so their impacts are nullified.  This means mathematically, there will be a point at which simply adding together quantum waves will cancel their individual effects and there will be no more measurable individual quantum effects anymore and classical mechanics takes centre stage.  I call this idea entanglement.

Size matters.  QED.

By the way, this means there are no parallel universes going on right now, ones where I am rich and famous or am the world’s greatest painter, and much of science fiction is well science fiction.  Sorry about that.

But it does mean that the sycamore tree on the green can exist even if no-one ever has observed it or a falling tree actually fall if not observed, because as all the individual waves of each particle entangle and interfere with each other they create existence, fixing things into space and time.  This philosophy and physics problem can be seen in works by George Berkeley or in physics forums, where a load of strange and complex answers are given.  Pragmatism should always rule over philosophy, as many things just are without being measured or proved; whether you can explain it is a different matter, but that does not stop it being so.