Does quantum mechanics mean everything is quantised?

Discussion in 'Physics & Math' started by Tailspin, Sep 17, 2019.

  1. Tailspin Registered Member

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    I have read about the quantisation of energy and from what I have read this is my understanding.
    When light is shone on an object, if it's the right amount of because one of the electrons in the atom to jump to a different level like a car changing gears or going up or down one step on the stairs. This action releases a photon with that level of energy.

    All light is made up of photons, the indivisible packets of energy which makes up the basis of quantum theory. However, although light can only be transmitted in whole packets, whole photons, the photons themselves can have any value. Photons can have 1 energy, 2 energy, 2.75 energy, but there is no such thing as half a photon. I imagine it's like boxes rolling along a conveyor belt, each one is identical in size and each one is a whole box but the manufacturer can have this model of box made in any size.
    Is that right or can light only come in a fixed number of values?

    The thing I find confusing is that when people talk about this they say energy is quantised.
    When they say energy do they mean light? Or do they mean energy itself, all forms of energy? Is electricity quantised? Heat? Gravity? Motion? Is all light quantised or only certain kinds of light?
    I have heard it said that absolutely everything is made of energy. If all energy is quantised as at mean that everything that exists and happens, everything that can will ever exist and have an is quantised? Does this mean life is like a digital screen and the quanta are the indivisible pixels that make up the image?
    On YouTube I saw a home-made documentary by young man who indeed said that absolutely everything was "stepped" every physical object, every motion we make.

    Part of the reason I'm thinking like this is my introduction to quantum mechanics was a documentary called Nova. When the announcer said all energy comes in discrete packets, the image on the screen broke apart into uniform cubes to illustrate this point. At once I thought you meant that every form of energy and thus absolutely everything is made up of quanta that are universally the exact same size and shape. Is that right?
    Also, I have read that the term quantum mechanics is misunderstood. That it's not all to do with quanta, but rather it is the study of physics at the very small level. Is that true?

    Some of you may remember that years ago, on this website, I started a lengthy discussion as to whether all possibilities are finite. I don't want to get back into a discussion about that here. But, the way I understand quantum mechanics, does it prove all possibilities are finite?

    I have also heard that quantum mechanics has been enormously successful and I'm not even sure if it's considered theoretical any more because people are using it to develop new technology. The success of quantum mechanics strikes me that none of this can be argued with. So is it possible to question the findings of quantum mechanics?

    If quantum mechanics is the study of the very small and and the quantisation of energy means the quantisation of light, then I for one think people should be clearer when they talk about it.
     
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  3. exchemist Valued Senior Member

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    Not everything is quantised. There are also continuum conditions in which there is no quantisation.

    And yes light quanta (photons) can have any frequency and hence energy and momentum, though they always (being bosons) carry one unit of spin. The frequency (hence momentum and energy) of the photons emitted by a source indeed depends on the size of the gaps between energy levels of the emitter. Quantisation is what determines the size of the gaps. This accounts for why different atoms emit and absorb light at specific frequencies that are characteristic for the element, why different molecular vibrations emit and absorb infra red radiation at particular frequencies. Even the rotation of molecules is quantised so that there are only certain permitted rates of rotation, and transitions between these give rise to the absorption and emission of microwaves. Your microwave oven makes the water molecules in your food spin faster, basically.

    So it is not true to think that light, for instance, is all made up of identical building blocks.

    So really, the "quantisation" is the quantisation of (bound states of) matter. It is the various states of matter that are constrained to have only certain values. When these change, they emit or absorb quanta of light of a particular frequency.
     
    Last edited: Sep 17, 2019
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  5. Tailspin Registered Member

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    So quantization also effects the speed the atoms spin? Like a car shifting gears?
    People write "energy is quantised," do the really mean light is quantised? Because to me at lease, the word energy is a much broader term, so to say energy is quantised is very misleading.
    What is and isn't quantised?
     
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  7. exchemist Valued Senior Member

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    Bound states of matter are quantised and so is radiation.

    This results in certain properties of matter and radiation being also quantised, including energy and angular momentum.

    This has effects throughout physics and chemistry. But yes, one of them is that molecules spin only at certain set speeds and shift from one to the next either by absorbing or emitting radiation, or by collision processes with other molecules.

    Energy in these systems is a property that is quantised, certainly, but it is not the only property that is. So saying "energy is quantised" is better than saying "light is quantised", but even that still does not really cover it.
     
    Last edited: Sep 18, 2019
  8. Tailspin Registered Member

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    So all the energy that belongs to a bound system is quantized? The energy it releases, it's state, what else? Is everything about a bound system is quantized?What about it's position? Can bound atoms only exist in a finite number of places like pixels on a screen?
    What is a bound system?

    Please keep in mind that my knowledge of this subject it limited to 2 documentaries and reading forums like this.
     
  9. exchemist Valued Senior Member

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    By a bound system I mean one in which the QM entity cannot move freely but is constrained to return repeatedly over a finite area of space. For instance an electron in an atom is attracted by the nucleus and moves around it all the time, unable to escape. Or a pair of atoms joined by a chemical bond, which can move vibrationally, by stretching the bond and then rebounding, but cannot escape from one another. Or a set of atoms bound together in a molecule that rotates, so that the atoms repeated pass the same position. Essentially anything that results in some form of periodic motion.

    But the properties of an atom or subatomic particle in free space are not quantised. You see this in atomic spectra. The spectral lines converge to a limit, beyond which there is a continuum. The continuum starts at the frequency corresponding to the energy needed to ionise the atom, i.e to excite an electron so that it has enough energy to escape the attraction of the nucleus completely.

    Strictly speaking, even motion is space becomes quantised if the atom or molecule is inside a container, although for a container with macroscopic dimensions the allowed energy (and momentum) values are so close together as to be indistinguishable from a continuum in practice. Look up "particle in a box" for more about this.
     
  10. Tailspin Registered Member

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    I appreciate your response but I'm having a hard time following it.

    Really, my training and education in science is limited to articles I've read online and the occasional documentary. I've never learned my times tables and actually took an adult numeracy course, I had just started learning about square numbers before I failed the course.

    I looked into the particle in a box thing on Wikipedia and according to my understanding, I imagine it being like a golf ball that can roll anywhere to any continuum of location in the room, the golf ball being a particle. But if you were to get a cardboard box and put the golf ball inside then although it could roll to any position within the box it could not leave the box. So if we had a series of boxes with one golf ball each inside, their positions could be considered quantised even though they could move freely within the confines of the box. Is that right?

    When I asked if motion was quantised I meant in the everyday macro world. If I’m waive my arm in an arc, is there a continuum of positions it can occupy? Or if everything is made of energy and all energies quantised, as it’s just moving through a finite set of possible positions like a dial on a blender? Is it just so small that we don’t notice it?

    This is a subject of great importance to me, I assumed that when they say energy is quantised that means all forms of energy, is that right? And since energy is quantised that means everything is quantised right? And if everything is quantised then it’s as if the world is one giant digital image, everything is divided into indivisible cubes of energy, is that right?

    I fear this to be true because as far as I know, quantum mechanics is the idea that everything is quantised and quantum mechanics is a field of science that’s highly successful and respected.

    But I have also read that quantum mechanics actually means the study of things at an atomic level. Which one is it?

    Also, if atoms are quantised as that mean they can only exist in one fixed position at a time like a pixel occupies a fixed position on a screen, one of a finite number of different possible positions? Or, even though atoms are quantised is it possible they can exist in a continuum of locations?

    Please answer each question listed above, thank you.
     
  11. exchemist Valued Senior Member

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    No I hate responding to long lists with more long lists. It tends to become very hard to follow the thread of the discussion. If you have a series of questions, let's break them into chunks, with just a couple of related queries in each post.

    I won't spend time on the particle in the box with you, as if you don't know much physics you may get confused by it.

    The paragraph I will respond to is the one starting "This is a subject of great importance to me." This paragraph indicates that you are working your way round to your psychological obsession about whether there is only a finite number of pictures it is possible for humanity to draw. You gave us all a runaround on this in another forum, to which I provide the link here: http://www.thescienceforum.com/biol...ics-perception-does-limit-our-perception.html

    I'm not doing that again. If you have other questions about QM that are unrelated to this unbalanced obsession of yours, I am happy to try to help. But since you admit you have been receiving therapy for this condition, for a number of years, I am not prepared to indulge it here.
     
  12. Tailspin Registered Member

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    85
    I am sorry, I had no idea you felt that way about long posts or that you or anyone on this site was connected to the other one. I don’t like to upset people and believe me I wasn’t trying to do that here or there.

    Please try to understand, art and creativity have been my life for as long as I can remember, it was everything to me, my single greatest joy in life, what gave my life purpose.

    Then, years ago, my father was driving home from a doctors appointment. My father is the single most intelligent and scientifically minded man I have ever known. He spent his whole life working in or at least connected to the scientific community, he subscribes to multiple magazines on science and technology and he has a passionate hobby and astronomy. But more than that, he doesn’t believe in anything that hasn’t been scientifically proven, he told me to my face that he has no belief in an afterlife, the metaphysical or the supernatural whatsoever.

    That day in the car we were talking and he told me about how all possibilities were finite because there are only so many ways matter can be arranged in any finite space. And I don’t mean he told me there was a theory that said so, indeed the word theory never came out of his mouth during the whole conversation. He told me about it with absolute certainty and any time I tried to poke a hole in it he simply counter argued it.

    The way he talked, I assumed that this wasn’t a theory at all, that it had already been proven and given its stamp of approval by whoever is in charge of certifying scientific facts. That this whole thing was a simple fact of life, that it was no more in dispute then the water cycle or gravity. And if my father, of all people in the world believed it then it had to be true because no untruth could work its way into his brain. And it didn’t help that it made perfect logical sense. Also I have a tendency to take things literally, especially if they come from someone who I believe to be an expert.

    I don’t want to believe in it, it’s the most horrible thing I’ve ever heard. But I feel like I have no choice.

    I know it’s perfectly possible for me to believe in whatever I want but honestly, I find that sort of thing detestable. I cannot stand the idea that people can just pick and choose to believe in whatever they want. But I assure you, that’s not as fascist as it sounds.

    I believe that if you are to choose a belief that it has to be a viable belief. You should only believe in what is true. And upon adopting a belief it should be based upon some amount of proof or at least devoid of any disproof.

    People say that everyone is entitled to their own belief but hypothetically, say you met someone who told you he believed the sun was a giant ball that was thrown across the sky each day by a giant cosmic raccoon. Society demands that he is entitled to his belief but still you would think this man was either very poorly educated or was mentally ill wouldn’t you? There are people in the real and modern world who genuinely believe the world is flat, which I think is particularly absurd considering we have satellite images, people who have circumnavigated the globe and even seen it from space. Personally I think all the Flat-earthers should have their heads examined.

    What I’m saying is that I could choose to believe that this theory that bothers me isn’t true but I detest that sort of behaviour. When I adopt a belief I always check to find out if it’s real first, only then do I deem it okay to proceed.

    I don’t want to believe in the theory so I’ve been trying to find out whether it’s true or not, going over every aspect and checking them out. feel that only then, when I’ve cleared every one of them would it be okay to choose to disbelieve in this theory. My father was no help, I don’t think even considers this to be a theory and he says he can’t remember where he heard it.

    With all due respect I know that the people on the science forums aren’t necessarily experts but you’re the closest thing I have access to. It’s not like I can just phone up a scientist and asked him a few questions. I actually did that once, she took my call and answer my questions as best she could but it was still very awkward.

    Therapy is probably too nice a word what I’ve been doing about this. I’ve been talking to councillors but they have been much help on this. They’re always looking for some sort of alternative, subconscious reason why you’re having a problem. Plus they have limited background in this field of science but again, is not as if I have anyone else to talk to about it.also, the counselling has been going well lately and I’m sort of between councillors at the moment.

    My previous counsellor said to “just stop thinking about it,” I told him that in my mind that was the same as accepting it andI was going to stop thinking about it when I decided that the theory wasn’t true. But he kept “No! Stop thinking about it! don’t come to any conclusion, never think about it again!” I told him I found that unacceptable but he wouldn’t shift his position and neither have I.

    I’ll give you one question in this post and I hope you answer it. What you said about the particle in a box, does that mean that the universe is made out of “cubes”of matter? I can only be arranged a finite number of ways like pixels on a screen?
     
  13. exchemist Valued Senior Member

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    If you make any more posts about this obsession of yours, I am going to add you to my Ignore list.
     
  14. Tailspin Registered Member

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    I understand, I just wanted to explain myself.
    Will you please answer my question or does that fall under my obsession.
     
  15. exchemist Valued Senior Member

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    Arfa's latest shows nicely the incompleteness of tryig ot treat physcial sysrem simply in terms of energy. To say you stat a wave You can't start a wave
    It falls squarely under your obsession.
     
  16. Tailspin Registered Member

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    So what if it does? If I get the right data my obsession will end.
     
  17. exchemist Valued Senior Member

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    Bye [click]
     

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