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Thread: Point Particles

  1. #1 Point Particles 
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    Why wouldn't a point particle with zero mass have infinite density? Why wouldn't a singularity be a type of point particle?


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    Quote Originally Posted by SowZ37 View Post
    Why wouldn't a point particle with zero mass have infinite density?
    Density of what ? If it has zero mass, it has also zero mass density.

    Why wouldn't a singularity be a type of point particle?
    A singularity is a region of space-time past which time-like and null geodesics cannot be extended ( geodesic incompleteness ), and it is covered by an event horizon; the laws of physics break down in this region, and our usual observables such as mass, charge, spin etc cease to be well defined there. The same is not true for elementary particles - the region of space-time they occupy is considered smooth and regular, and they are endowed with properties such as mass, charge, spin etc. In the Standard Model they are treated as point-like for two reasons - first, it makes the maths a whole lot easier; second, deep inelastic scattering experiments in particle accelerators have not revealed any internal structure for this particles ( at currently achievable energies ). So long as there is no theoretical or observational reason to do otherwise, they will hence be treated as point-like as a matter of convenience and simplicity.

    There are certain "beyond the Standard Model" theories such as String Theory and the black hole electron model which attempt to abandon the point particle picture, but they aren't currently considered accepted physics ( rather hypotheses ).


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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by SowZ37 View Post
    Why wouldn't a point particle with zero mass have infinite density?
    Density of what ? If it has zero mass, it has also zero mass density.

    Why wouldn't a singularity be a type of point particle?
    A singularity is a region of space-time past which time-like and null geodesics cannot be extended ( geodesic incompleteness ), and it is covered by an event horizon; the laws of physics break down in this region, and our usual observables such as mass, charge, spin etc cease to be well defined there. The same is not true for elementary particles - the region of space-time they occupy is considered smooth and regular, and they are endowed with properties such as mass, charge, spin etc. In the Standard Model they are treated as point-like for two reasons - first, it makes the maths a whole lot easier; second, deep inelastic scattering experiments in particle accelerators have not revealed any internal structure for this particles ( at currently achievable energies ). So long as there is no theoretical or observational reason to do otherwise, they will hence be treated as point-like as a matter of convenience and simplicity.

    There are certain "beyond the Standard Model" theories such as String Theory and the black hole electron model which attempt to abandon the point particle picture, but they aren't currently considered accepted physics ( rather hypotheses ).
    All right, makes sense why a singularity isn't a type of point particle.

    But can't a point particle have point mass? A nonzero mass particle with no volume? No matter how small the mass, any nonzero mass in a point that takes up no space would be infinite density, wouldn't it?
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  5. #4  
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    Quote Originally Posted by SowZ37 View Post
    But can't a point particle have point mass? A nonzero mass particle with no volume? No matter how small the mass, any nonzero mass in a point that takes up no space would be infinite density, wouldn't it?
    Yes, if you treat an electron as a true point particle, then a nonzero mass implies an infinite mass density. That is what happens if you apply classical physics (and, for that matter, GR) to a true point particle. Indeed, GR says that an electron should be a black hole (which would then evaporate quickly by Hawking radiation). Embarrassments like this one are what motivate physicists to seek things like a combination of quantum mechanics with GR, but it is an unfinished quest.
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    Quote Originally Posted by tk421 View Post
    Quote Originally Posted by SowZ37 View Post
    But can't a point particle have point mass? A nonzero mass particle with no volume? No matter how small the mass, any nonzero mass in a point that takes up no space would be infinite density, wouldn't it?
    Yes, if you treat an electron as a true point particle, then a nonzero mass implies an infinite mass density. That is what happens if you apply classical physics (and, for that matter, GR) to a true point particle. Indeed, GR says that an electron should be a black hole (which would then evaporate quickly by Hawking radiation). Embarrassments like this one are what motivate physicists to seek things like a combination of quantum mechanics with GR, but it is an unfinished quest.
    Ah, okay. When I read what a point particle was, I visualized it turning into a black hole and figured I was way off in my visualization somewhere, (obviously,) but it is more a weakness in the various theories not always meshing perfectly?
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    Quote Originally Posted by SowZ37 View Post
    Ah, okay. When I read what a point particle was, I visualized it turning into a black hole and figured I was way off in my visualization somewhere, (obviously,) but it is more a weakness in the various theories not always meshing perfectly?
    We know that GR and quantum theory are incomplete. Your excellent question about point particles falls into, well, a hole in our knowledge, although theorists are hard at work. As one physicist has remarked, "Theorists are very clever; they can crank out theories in weeks that take experimentalists decades to falsify."

    If you compute the Schwarzschild radius of an electron-as-black-hole, you get something like 10^-57m, if memory serves. Even if my memory is faulty, the exponent is large (and negative). The point is that the event horizon would be vanishingly small in radius. We don't have a particle accelerator capable of probing the corresponding energy levels (and likely never will). However, since all electrons seem to be identical, nothing seems to be "falling in," nor are they evaporating away. So, experimentally we can say that electrons aren't turning into black holes. Whatever theory ends up subsuming GR and quantum theory, it will have to account for that experimental observation.
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  8. #7  
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    Oh look, a less than subtle sock puppet of Water Nosfim/ Water N. Still as incoherent as ever.

    EDIT: The posts that this and the one below were a response to have been deleted.
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  9. #8  
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    Never a coherent one from you, all you have ever posted (with multiple accounts) is bullshit and word salad.
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  10. #9  
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    Quote Originally Posted by SowZ37 View Post
    Why wouldn't a point particle with zero mass have infinite density? Why wouldn't a singularity be a type of point particle?
    First we should understand what mass is? This needs us to know the basic component of material. Point particle is a math concept only. Material has mass or energy and volume.
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    Quote Originally Posted by SowZ37 View Post
    Why wouldn't a point particle with zero mass have infinite density? Why wouldn't a singularity be a type of point particle?

    Actually, classical theory predicts this exactly!

    If we perform an integral on the classical energy which reduces the radius to zero, the energy blows up to infinity! Some physicists believe this is an indication that particles are not actually truly point like at all.
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    Quote Originally Posted by Chesslonesome View Post
    Some physicists believe this is an indication that particles are not actually truly point like at all.
    "A point particle (ideal particle or point-like particle, often spelled pointlike particle) is an idealization of particles heavily used in physics."
    Point particle - Wikipedia, the free encyclopedia
    SayBigWords.com/say/3FC

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    "Religions are like sausages. When you know how they are made, you no longer want them."
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    Quote Originally Posted by RedPanda View Post
    Quote Originally Posted by Chesslonesome View Post
    Some physicists believe this is an indication that particles are not actually truly point like at all.
    "A point particle (ideal particle or point-like particle, often spelled pointlike particle) is an idealization of particles heavily used in physics."
    Point particle - Wikipedia, the free encyclopedia

    Depends on the physicist. Obviously not all particles can be pointlike. An electron has a radius to something like as a lower limit (or an upper limit, I forget now).

    Of course, this doesn't change the fact that reducing the radius to zero does result in singularity.
    Last edited by Chesslonesome; April 25th, 2014 at 08:55 PM.
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    Quote Originally Posted by Chesslonesome View Post
    An electron has a radius to something like
    Nope,


    as a lower limit (or an upper limit, I forget now).
    You can't play fast with these things. It is the upper limit. You can stop pretending now.
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  15. #14  
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    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by RedPanda View Post
    Quote Originally Posted by Chesslonesome View Post
    Some physicists believe this is an indication that particles are not actually truly point like at all.
    "A point particle (ideal particle or point-like particle, often spelled pointlike particle) is an idealization of particles heavily used in physics."
    Point particle - Wikipedia, the free encyclopedia
    Depends on the physicist.
    No it doesn't.
    You implied that the accepted understanding is that point particles are actually points.
    You are wrong.
    SayBigWords.com/say/3FC

    "And, behold, I come quickly;" Revelation 22:12

    "Religions are like sausages. When you know how they are made, you no longer want them."
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  16. #15  
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    If string theory is true, are particles a bit of an illusion? Could you, if you wanted to simplify it for understanding, visualize a 'particle' as a sort of wave/frequency along the strings themselves?
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    An electron has a radius to something like
    Nope,


    as a lower limit (or an upper limit, I forget now).

    You can't play fast with these things. It is the upper limit. You can stop pretending now.

    I'm working on a memory that is just as infallible as yours. And by the way, the 5-1 is meant to be 1-5 it was a typo; I've been typing all day, give me some room.
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    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    An electron has a radius to something like
    Nope,


    as a lower limit (or an upper limit, I forget now).

    You can't play fast with these things. It is the upper limit. You can stop pretending now.

    I'm working on a memory that is just as infallible as yours. And by the way, the 5-1 is meant to be 1-5 it was a typo; I've been typing all day, give me some room.
    BS, you simply don't know and you posture as if you did.
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    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
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    The latter is for an extremal.
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  21. #20  
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    Quote Originally Posted by Chesslonesome View Post
    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
    No one is buying your crank BS, Reiku.
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
    No one is buying your crank BS, Reiku.
    I'm not causing anyone trouble and I am speaking the truth. Why do you feel the need to attack me at any given instant?

    Are things really this personal?
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    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
    No one is buying your crank BS, Reiku.
    I'm not causing anyone trouble and I am speaking the truth.
    No, you are not, you are spreading horse manure. This is a science forum, you need to practice your agriculture elsewhere.
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
    No one is buying your crank BS, Reiku.
    I'm not causing anyone trouble and I am speaking the truth.



    No, you are not, you are spreading horse manure. This is a science forum, you need to practice your agriculture elsewhere.

    I just posted a bloody link for you. How can you possibly call me into question when I back every statement I ever make when pressed? Even yesterday when you trolled my thread to hell, Markus threw it in the trash. I bet you felt great when it happened?

    It had nothing to do with the content, he even replied to the content and simplified the equation. I'm lost as to how you can get away with openly abusing people like this with no consequences?

    Are you a paying member here? There must be a catch.
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    Quote Originally Posted by Chesslonesome View Post


    I just posted a bloody link for you.
    The link does not support the horse manure you've been spreading. Go find an agriculture forum.
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  27. #26  
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    Quote Originally Posted by Chesslonesome View Post
    How can you possibly call me into question when I back every statement I ever make when pressed?
    Because you don't.
    SayBigWords.com/say/3FC

    "And, behold, I come quickly;" Revelation 22:12

    "Religions are like sausages. When you know how they are made, you no longer want them."
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    Quote Originally Posted by RedPanda View Post
    Quote Originally Posted by Chesslonesome View Post
    How can you possibly call me into question when I back every statement I ever make when pressed?
    Because you don't.

    I do when asked. Like I linked a page about the number 10^-51m.
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post


    I just posted a bloody link for you.
    The link does not support the horse manure you've been spreading. Go find an agriculture forum.


    Yes it does, if you read it. Not look at it, read it.
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    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post


    I just posted a bloody link for you.
    The link does not support the horse manure you've been spreading. Go find an agriculture forum.


    Yes it does, if you read it. Not look at it, read it.
    No, it doesn't. It WOULD its Schwarzschild radius IF the electron WERE a black hole. The electron is NOT a black hole. Give it a rest, Reiku, go find an agronomy forum where you can freely spread your horse manure.
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by chesslonesome View Post


    i just posted a bloody link for you.
    the link does not support the horse manure you've been spreading. Go find an agriculture forum.


    yes it does, if you read it. Not look at it, read it.
    no, it doesn't. It would its schwarzschild radius be if the electron were a black hole. The electron is not a black hole. Give it a rest, reiku, go find an agronomy forum where you can freely spread your horse manure.


    That is what i said!! I said it was for extremal. Please start reading things properly.

    Does typing in bold help?
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    Actually come to think of it, you probably didn't know what it meant.
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    Quote Originally Posted by Chesslonesome View Post
    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
    You continue to lie, this is exactly what you said. Which is obviously wrong.
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    Well actually there are two calculations, one for 10^{-15}m and one that calculates 1.35 x 10-51 m.
    You continue to lie, this is exactly what you said. Which is obviously wrong.

    HINT: As in post 19.
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    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    An electron has a radius to something like
    Nope,


    as a lower limit (or an upper limit, I forget now).

    You can't play fast with these things. It is the upper limit. You can stop pretending now.

    I'm working on a memory that is just as infallible as yours. And by the way, the 5-1 is meant to be 1-5 it was a typo; I've been typing all day, give me some room.
    ....and some more lying and weaseling from Reiku.
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  36. #35  
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    Hit or a miss this time? If your conversational skills and attention span are not up to scratch, perhaps forums aren't the place for you? Unless you need glasses?
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  37. #36  
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    An electron has a radius to something like
    Nope,


    as a lower limit (or an upper limit, I forget now).

    You can't play fast with these things. It is the upper limit. You can stop pretending now.

    I'm working on a memory that is just as infallible as yours. And by the way, the 5-1 is meant to be 1-5 it was a typo; I've been typing all day, give me some room.
    ....and some more lying and weaseling from Reiku.

    Anything I say is a lie in your books.

    You're bent on it.
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  38. #37  
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    Really... it WOULDN'T matter if I told you the grass was green. You'd still call me a liar. It's the only way you know how to try and undermine me and my work.
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  39. #38  
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    Quote Originally Posted by Chesslonesome View Post
    It's the only way you know how to try and undermine me and my work.
    There is no work to "undermine", just your deep seated delusions, Reiku.
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  40. #39  
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    Quote Originally Posted by xyzt View Post
    Quote Originally Posted by Chesslonesome View Post
    It's the only way you know how to try and undermine me and my work.
    There is no work
    Trust me, you are a piece of work.
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