Monday, February 11, 2008

Quantum Philosophy - Prologue

My knowledge of the subject is rudimentary, from my perspective, so I'll try to explain to the best of my abilities. Plus I'll try to place my tendency to go to the moon and back when discussing something on a leash.

To start the subject up, I'd like to quote something that was said in the course "introduction to quantum mechanics". The professor started the class by saying this (paraphrase):

Look, if you teach an introductory course on quantum mechanics, and the students don't have nightmares for weeks, tear their hair out, wander around with bloodshot eyes, etc., then you probably didn't get the point across.


A lot of great thinkers in the past had a tough time swallowing what quantum mechanics indicated about our reality, Einstein was quoted on the subject saying "God doesn't play dice with the universe".

Essentially while classical Newtonian physics can predict every fall of the sparrow, quantum mechanics can only leave us with possibilities. The real trouble with quantum mechanics doesn't arise from the fact that we can't predict the future in it ala classical physics. The real trouble arises from the fact that not only is that the future is indeterministic, the past is also indeterministic. Also that the probabilistic nature of quantum mechanics doesn't arise from our own ignorance like statistical probabilities it is an inherent attribute of the system .

Still reading ?? REALLY ?

Since the days of Democritus it was thought that everything tangible in this universe is made up of atoms that form the building blocks of our reality, Well quantum mechanics is the study of subatomic particles, the building blocks of all the universe.

So lets look at a simple experiment. you remember the science experiment where you have a tank of water and u place and object with two slits and turn on the wave generator to see how waves interfere with each other ? And do you remember them referring to light as both wave and particle in nature.
Well that experiment can be done with light.


double-slit experiments reveal that photons,
the quantum entities giving rise to light and other
forms of electromagnetic radiation, act both like
particles and like waves. A single photon will
strike the screen in a particular place,
like a particle (left)- But as more photons strike
the screen, they begin to create an interference pattern
(center). Such a pattern could occur only if each photon
had actually gone through both slits, like a wave (right).


If that isn't baffling enough, if you only permit one photon to pass through the slits. The interference pattern is still observed suggesting that wave went through. But when you add an apparatus that can detect which slit the photon passed through the interference pattern disappears. This experiment can be replicated on electrons, neutrons, atoms, and theoretically to other bigger things.

It is as if what we are experementing on is making future predictions and providing us with the answers that we want to see.

I'll stop here for this post, and let you think about what implications such result can have.

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17 Comments:

  • You surprised me with the amount of posts. I am trying to comprehend the first one in order to be able to build on it and understand the others.

    So here you are trying to prove that photons move in waves?

    By Blogger The Observer, At 20/2/08 17:28  

  • well i wanted to post them all at the same time so thats why it took a while. all am saying here is that experimentally it all depends on what your looking to prove .

    if you want to prove that they are waves you can see them as waves, and if you want to see them as particles you can see them as particles. but you can never see them as waves and particles at the same time (imagine a particle moving along a sine wave kind of thing)
    and its not about the short coming of instrumentation (this is the simplest experiment to prove that point but more elaborate ones have been done with similar results) its just that particles are neither waves or particles rather than suggesting that they are both.

    By Blogger No_Angel, At 20/2/08 17:42  

  • More confusion here :)

    So you say particles are neither waves or particles, and not both either?

    I guess that it is here a problem of defineing the properties of those particles. Are they solid matter or a type of contained energy? What is it exactly?

    By Blogger The Observer, At 20/2/08 18:08  

  • you know how they described to us atoms as the sun with little electrons(planets) orbiting it.
    now think of them as looking like that from far away.
    but when you get closer you notice that the reality is more fuzzy and its just a concentration of energy like you mentioned

    now in terms of movement we imagine them as a billiard ball that moves in unity
    but it might be closer to reality to imagine that energy disappearing from one side and appearing on the other that might make it look like a solid mass.

    hmm hopefully that describes the nature of those particles a bit better. now regarding us viewing them as particle and waves there are 2 interesting things; one that they cant be both at the same time and they react subjectively.
    two that either particle or wave is a behavior they exhibit rather than what they are.

    By Blogger No_Angel, At 20/2/08 19:17  

  • http://www-personal.umich.edu/~janhande/sizedmatter/sizedmatter_images.htm
    in case it helps, this is a visualization of what those particles actually look like.

    By Blogger No_Angel, At 20/2/08 19:26  

  • So they are tiny things that have a wave and matter attributes.

    But I was thinking if that is all irrelevent if you dont go deep inside the atom and keep atom as your base of interaction between elements in the universe. We still have classical mechanics valid for measruements? right?

    By Blogger The Observer, At 21/2/08 10:50  

  • by looking at that level you are looking at the basic element of the universe. so the interpretations are explaining why that behavior can't be observed on macro level easily.
    since the discovery of elements it was known that that the properties of a building block is maintained in a bigger structure.
    so since this is the building block and it exhibits such properties there must be a reason why this doesn't occur. so actually it is more relevant since it is the bigger scope of things while classical physics is just a special case.

    actually this experiment can be done with much bigger things, protons and even small bacteria(but it would have to move very slowly). so yeah it still applies.

    By Blogger No_Angel, At 21/2/08 11:09  

  • I have a comment about the wave-particle duality. Saying that photons are neither waves nor particles nor both isn't accurate.

    Wave-particle duality is easily understood when you understand the Mass-Energy equivalence given by the famous equation "E=m*c^2".

    A particle is a mass. Mass has energy. So when a mass moves, energy moves.

    Waves are the movement of energy. So its seems very logical that when mass movement is detected, also energy movement is detected (which is what defines a wave).

    By Blogger Devil's Mind, At 21/2/08 21:04  

  • DM, now that equation i understand. Does that mean: with movements matter loses some of its mass as energy?

    By Blogger The Observer, At 22/2/08 12:45  

  • DM ok that equation is of special relativity, which doesn't hold under high gravitational fields and isn't applicable.
    either way what that equation states is that mass and energy are equivalent so you lost me when you said that "Waves are the movement of energy."
    since waves is only one way of many that energy/particels can move with.
    even if we expand to general relativity there are still a lot of problems trying to bridge the two theories.
    So i'll stick to saying that that the duality of photons is just 2 ways that it translates its energy in.

    observer yup that is true if you are moving at speeds close to the speed of light, otherwise the effect is negligible on the mass

    By Anonymous bambam, At 23/2/08 15:25  

  • Energy and mass are like two faces of the same coin. Wherever there is mass, there is energy.

    So when energy moves, its mass moves with it. And when mass moves, it energy moves with it. So every moving particle [not only light, but any particle in general] has also its energy moving with it.

    The higher the amount of energy moving, the smaller is the wavelength is. So any mass moving, has a wave moving with it.

    The question is: Why do observe interference with light, but not other moving particles?! The answer is size!

    Remember, more energy smaller wavelength. Smaller wavelengths are harder to detect! Besides, when the size of the mass is larger than the wave itself, then the mass practically hides the wave inside of it, so we don't detect it. But its there!

    By Blogger Devil's Mind, At 2/3/08 04:14  

  • DM, now that equation i understand. Does that mean: with movements matter loses some of its mass as energy? - Yes. When a mass moves it gains kinetic energy from the source of the force. Kinetic energy has mass, and hence the mass gains more mass!

    By Blogger Devil's Mind, At 2/3/08 04:34  

  • Read this.

    I actually once discussed those ideas (in an indirect manner) on my blog here.

    In there I discussed that energy and mass units should be unified. And that time and space units should be unified. And this indirectly means that the concept of a wave and a particle merge into one concept.

    I have crossed the proposition because at that time I wasn't sure if the idea is really fit. But if the proposition to unify waves and particles as one concept is taken, this will indirectly mean that time and space are actually the same thing!

    By Blogger Devil's Mind, At 2/3/08 04:45  

  • "Wherever there is mass, there is energy."
    a photon has ZERO rest mass ...

    "energy and mass units should be unified."
    yeah sounds fancy to do that to over come duality the only problem is the cost when moving from energy to mass and vice versa is too high so it's highly inefficient to unify them, plus ur idea of creating mass just throws entropy out of the window :D

    By Blogger No_Angel, At 2/3/08 11:11  

  • a photon has ZERO rest mass ... - True. But "rest mass" and "mass" are two different concepts! Light has non-zero mass, but zero rest mass!

    Rest mass is the mass that an object has while not moving [remember that moving itself is a relativistic concept]

    As I explained to observer, an object gains mass when it moves. So light gets mass when it moves...

    So yes, when light stops moving it ceases to exist... Maybe thats why it keeps moving as fast as it can!! :)

    By Blogger Devil's Mind, At 2/3/08 17:27  

  • "moving from energy to mass and vice versa is too high" - Dude, the whole idea is that mass and energy are the same thing!! We don't need to hop from one to another!

    By Blogger Devil's Mind, At 2/3/08 18:22  

  • " Dude, the whole idea is that mass and energy are the same thing!! We don't need to hop from one to another!"
    Dude .... mass as in rest mass is definitely not the same thing, hell its not even universally defined in general relativity
    and even in special relativity rest mass is rest mass... unless your talking about relativistic mass (its the same as energy) then yeah ... but that is def. not mass in the classical sense and barely anyone anymore refers to it as mass .... sheesh ...

    By Anonymous bambam, At 2/3/08 19:37  

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