ACUV Posted June 5, 2012 Posted June 5, 2012 If a stone was dropped from a very high building and collided with the pavement, would any electrons physically touch?
timo Posted June 6, 2012 Posted June 6, 2012 Electrons do not have a 3D shape. Hence, it's not clear what it means for electrons to "physically touch".
juanrga Posted June 6, 2012 Posted June 6, 2012 If a stone was dropped from a very high building and collided with the pavement, would any electrons physically touch? Electrons are not tiny hard balls. If you are asking if they will collide ('touch') as billiard balls, the answer is "no".
ACUV Posted June 6, 2012 Author Posted June 6, 2012 Electrons do not have a 3D shape. Could you elaborate?
elfmotat Posted June 6, 2012 Posted June 6, 2012 Could you elaborate? They are point particles, i.e. they have no volume.
elfmotat Posted June 7, 2012 Posted June 7, 2012 How can something have mass but no volume? Why do you find this strange? Why do you think things must have volume to possess mass?
ACUV Posted June 7, 2012 Author Posted June 7, 2012 So, elfmotat, assuming electrons have no volume but have mass, is the nucleus likewise? I do hope you have a mainstream accepted view of this type of thing.
elfmotat Posted June 7, 2012 Posted June 7, 2012 (edited) So, elfmotat, assuming electrons have no volume but have mass, is the nucleus likewise? I do hope you have a mainstream accepted view of this type of thing. The quarks that make up protons and neutrons are similar to the electron in the sense that they are point particles. Protons and neutrons themselves do occupy a certain amount of volume, though the concept of volume in quantum physics is not very clear-cut. It's difficult to say how much space something occupies due to inherent uncertainties. I also assure you that I'm not making anything up. Edited June 7, 2012 by elfmotat
Greg H. Posted June 7, 2012 Posted June 7, 2012 (edited) Electrons occupy a certain amount of volume as well. In quantum mechanics, the concept of a point particle is complicated by the Heisenberg uncertainty principle: Even an elementary particle, with no internal structure, occupies a nonzero volume. For example, a 1s electron in a hydrogen atom occupies a volume of ~10-30 m3. There is nevertheless a distinction between elementary particles such as electrons or quarks, which have no internal structure, versus composite particles such as protons, which do have internal structure: A proton is made of three quarks. Elementary particles are sometimes called "point particles", but this is in a different sense than discussed above. For more details see elementary particle. See Point Particle for more details. Edited June 7, 2012 by Greg H. 1
timo Posted June 7, 2012 Posted June 7, 2012 Electrons occupy a certain amount of volume as well.That happens not to be the point here. Electrons do not have a 3D shape. As a consequence of that, they do not have a volume (I find not having a 3D shape the more relevant property, but I acknowledge that people think "zero volume" or "no volume" sounds more scientific). That they can exist within some volume ("occupy it") is neither relevant for the question whether they can touch (in the most natural interpretation of "touch", at least), nor particularly interesting or surprising.
swansont Posted June 7, 2012 Posted June 7, 2012 I think one needs to note that "occupies a volume" is a slightly different statement than "has a volume". The latter is a statement about the intrinsic properties of the particle while the former is more concerned with how it behaves. timo is right; the electron has not been found to have a 3D shape.
RichIsnang Posted June 7, 2012 Posted June 7, 2012 How can an electron collide with things if it has no volume? And what do you mean by has no 3d shape, does it have a 2d or 1d shape?
juanrga Posted June 7, 2012 Posted June 7, 2012 How can an electron collide with things if it has no volume? And what do you mean by has no 3d shape, does it have a 2d or 1d shape? Electronic collisions are changes in velocity determined mainly by electromagnetic interactions. Electrons are always separated a minimum non-zero distance [math]r_{min}[/math] from the target with which they collide. For instance the collision of two electrons can look as follows (classical approach) 1
Greg H. Posted June 7, 2012 Posted June 7, 2012 That happens not to be the point here. Electrons do not have a 3D shape. As a consequence of that, they do not have a volume (I find not having a 3D shape the more relevant property, but I acknowledge that people think "zero volume" or "no volume" sounds more scientific). That they can exist within some volume ("occupy it") is neither relevant for the question whether they can touch (in the most natural interpretation of "touch", at least), nor particularly interesting or surprising. I think one needs to note that "occupies a volume" is a slightly different statement than "has a volume". The latter is a statement about the intrinsic properties of the particle while the former is more concerned with how it behaves. timo is right; the electron has not been found to have a 3D shape. I stand (or sit as the case may be) corrected. Particle physics is not something I am intimately familiar with, so I appreciate the correction when I veer off in the wrong direction. Thank you both.
ACUV Posted June 7, 2012 Author Posted June 7, 2012 If the self same stone as earlier was dropped from a very high building and collided with the pavement as previously, would any electron from the stone swap it's orbit for a new orbit around a pavement nucleus or vice versa?
Greg H. Posted June 7, 2012 Posted June 7, 2012 If the self same stone as earlier was dropped from a very high building and collided with the pavement as previously, would any electron from the stone swap it's orbit for a new orbit around a pavement nucleus or vice versa? I am fairly certain that physical collisions of that nature aren't going to result in the spontaneous formations of previously absent chemical bonds. Though I suppose if the collision generated sufficient heat, it may - I'm just not sure about that.
swansont Posted June 7, 2012 Posted June 7, 2012 I am fairly certain that physical collisions of that nature aren't going to result in the spontaneous formations of previously absent chemical bonds. It's not the same as forming a new chemical bond; you can liberate electrons from some materials quite easily. Ever rubbed a balloon on a dry day?
Greg H. Posted June 7, 2012 Posted June 7, 2012 It's not the same as forming a new chemical bond; you can liberate electrons from some materials quite easily. Ever rubbed a balloon on a dry day? No, but I have four cats - the effect is the same, I think.
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