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If space is quantized, then you move in steps. What happens right before each step?

  1. Aug 20, 2010 #1
    I understand that space might be made up of individual units, such that you can't have a location which is between two units. When moving, a particle would just "pop" into the next unit repeatedly instead of smoothly moving - like how a computer screen works with pixels. Do I understand that at least somewhat correctly?

    Ok, so let's consider a particle in Cell A which is moving, eventually to reach Cell B. What is keeping the particle in cell A from moving instantly to B? In other words, what is going on in that cell that determines how long the particle must stay there before it moves to Cell B? How does Cell A "know" the velocity of the particle so that it can allow the particle to continue to Cell B at the correct time? What is keeping track of how long the particle is in Cell A? Could you take a snapshot of the universe and by looking into Cell A, be able to tell how soon the particle would move? Hopefully you can see what I'm getting at.

    Is it building up some kind of tension which must reach a certain threshhold before breaking? How does that work? Does it gradually exist in B while gradully disappearing from A? Also, if you have to be in a certain cell, doesn't that mean you know the location and thus cannot determine the velocity at all?
     
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  3. Aug 20, 2010 #2
    Re: If space is quantized, then you move in steps. What happens right before each ste

    It is? Have there been experiments that show this to be true?
     
  4. Aug 20, 2010 #3
    Re: If space is quantized, then you move in steps. What happens right before each ste

    That's why I said "if space is quantized" and "might be made up of individual units".
     
    Last edited: Aug 20, 2010
  5. Aug 20, 2010 #4

    DaveC426913

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    Re: If space is quantized, then you move in steps. What happens right before each ste

    He's talking about planck length.

    Meatbot, just because there is a smallest length does not mean things cannot move discretely. The units do not represent rigid boxes of space.
     
  6. Aug 20, 2010 #5
    Re: If space is quantized, then you move in steps. What happens right before each ste

    When there is an energy field, energy levels can be defined. Particle which are affected by this energy field can only occupy certain space which is accordance with these energy levels. In such a fixed system, space is quantized.

    However, the shape of an energy field can be made to varying continuously. By doing so, the affected particle is able to continuously occupy any spatial coordinate. In this sense, and ultimately, space is not quantized.
     
  7. Aug 20, 2010 #6
    Re: If space is quantized, then you move in steps. What happens right before each ste

    ok, thanks. I didn't know it was conceived that way....so things could be moving much slower than for example 1 planck length/year with relation to us and we just wouldn't be able to observe it until the year was over? So it's possible to get your velocity up to c-(.5 planck length/year)?

    Actually I don't understand how even if there is a shortest possible distance, that something can still move discretely. If it could, it would be able to move less than the shortest distance.

    Are you saying that there really isn't a shortest distance, just a shortest distance we can actually measure?
     
    Last edited: Aug 20, 2010
  8. Aug 20, 2010 #7

    DaveC426913

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    Re: If space is quantized, then you move in steps. What happens right before each ste

    Well no, I'm just saying the whole thing isn't as literal as you're making it out to be.

    For example, the scale we are talking about (10-33m) is much much smaller than the scale at which any kind of discreteness in particles exists anyway (10-15m). i.e. a proton is a billion billion Plank units in diameter.
     
  9. Aug 20, 2010 #8

    diazona

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    Re: If space is quantized, then you move in steps. What happens right before each ste

    Here's what I'd say: the Planck length is the unique length that can be formed by a product of the fundamental constants of free space (gravitational constant, Planck's constant, and speed of light). So the reason it's so special is that, roughly speaking, it's "nature's choice" of a length unit (at least, you'd have a harder time making that argument about any other length). Now, it just happens to be a really really tiny length, and for that reason a lot of people speculate that it might be some sort of "shortest length," but the more I learn, the less convinced I am that that has to be true.
     
  10. Aug 20, 2010 #9
    Re: If space is quantized, then you move in steps. What happens right before each ste

    I thought a proton was considered a point particle. How do you get that value for its diameter?
     
  11. Aug 20, 2010 #10

    diazona

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    Re: If space is quantized, then you move in steps. What happens right before each ste

    Now we know that the proton isn't a point particle, it's made of quarks and gluons. The value for its diameter probably comes from high-energy scattering experiments (particle accelerators). Basically, you get two beams of protons circling around in opposite directions, and the larger the proton is, the more likely it is that two of them will hit each other each time the beams cross. So knowing how many protons there are in the beams, how fast they're going, and how many collisions you get, you can figure out how large an individual proton is. (This is of course vastly simplified; there are also other, more complicated experimental and theoretical methods for determining the size of the proton)
     
  12. Aug 20, 2010 #11
    Re: If space is quantized, then you move in steps. What happens right before each ste

    oh yea, duh

    lol
     
  13. Aug 20, 2010 #12
    Re: If space is quantized, then you move in steps. What happens right before each ste

    Ahem, definately smaller than my bathroom scale! Long live the proton! (and quarks and gluons, et al).
     
  14. Aug 20, 2010 #13
    Re: If space is quantized, then you move in steps. What happens right before each ste

    Consider a photon. It goes from zero to c in zero distance.
    That is, there is no 1/8th, 1/4th or 1/2 c, etc... in that scenario.
    Odd? Yes, but that's the way it is.
     
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