About the maximal electrostatic potential energy U(r) of a pair electron-positron at rest with distance r
in [Relativity]
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From: Hikaru Masayoshi on 22 Jul 2010 15:18 On Jul 22, 8:58 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Jul 19, 4:56 pm, va...(a)icmf.inf.cu wrote: > > > On 19 jul, 13:59, PD <thedraperfam...(a)gmail.com> wrote:> On Jul 16, 2:16 pm, va...(a)icmf.inf.cu wrote: > > > > > I suppose we are all in agreement about the increase of U(r) with an > > > > increase of r. Has U(r) a finite maximal limit value when r tends to > > > > infinite? In case of positive answer, which is that maximal value? > > > > You may have heard in freshman physics that the zero point of > > > potential is physically arbitary. In all interactions, the only thing > > > that is important is the *change* in potential energy between initial > > > and final states, and that number is independent of the overall scale.. > > > Well, you dont answer my question, but what you say is compatible > > with an infinite value for U(r) when r tends to infinite (any > > arbitrary additive constant doesnt change the infinite). > > Read what I wrote. U(r)=0 is quite finite. i disagree, only if U is a conservative function nothing tells you that electron-positron obeys conservative functions over large distances, universe maybe you are not quite familiar with mathematics
From: valls on 23 Jul 2010 08:25 On 22 jul, 13:58, PD <thedraperfam...(a)gmail.com> wrote: > On Jul 19, 4:56 pm, va...(a)icmf.inf.cu wrote: > > > On 19 jul, 13:59, PD <thedraperfam...(a)gmail.com> wrote:> On Jul 16, 2:16 pm, va...(a)icmf.inf.cu wrote: > > > > > I suppose we are all in agreement about the increase of U(r) with an > > > > increase of r. Has U(r) a finite maximal limit value when r tends to > > > > infinite? In case of positive answer, which is that maximal value? > > > > You may have heard in freshman physics that the zero point of > > > potential is physically arbitary. In all interactions, the only thing > > > that is important is the *change* in potential energy between initial > > > and final states, and that number is independent of the overall scale.. > > > Well, you dont answer my question, but what you say is compatible > > with an infinite value for U(r) when r tends to infinite (any > > arbitrary additive constant doesnt change the infinite). > > Read what I wrote. U(r)=0 is quite finite. > I dont understand your comment. When you write U(r)=0 you are only assigning to U(r) the finite value 0 at some arbitrary r. What relation do you establish between this and my question (not answered by you yet) about if exist or not a finite maximal limit value for U(r) when r tends to infinite? My last comment is related with the fact that if any finite value is selected for the arbitrary r, this is compatible with an infinite value for U(r) when r tends to infinite (and not compatible if the arbitrary r is infinite). > > > > Anyway, I > > consider more interesting the other alternative with a finite maximal > > limit value. I just address it in an answer to dlzc (David) in this > > same thread. I consider adequate to refer you to it, instead of > > repeating here my analysis. > > > > It is frequently customary to put U(r=infinity) = 0, so that all > > > values of U(r) for finite r are negative. But this by no means > > > required and many problems are more convenient to solve with a > > > completely different choice. > > > > PD > > > RVHG (Rafael Valls Hidalgo-Gato) RVHG (Rafael Valls Hidalgo-Gato)
From: PD on 23 Jul 2010 09:40 On Jul 23, 7:25 am, va...(a)icmf.inf.cu wrote: > On 22 jul, 13:58, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Jul 19, 4:56 pm, va...(a)icmf.inf.cu wrote: > > > > On 19 jul, 13:59, PD <thedraperfam...(a)gmail.com> wrote:> On Jul 16, 2:16 pm, va...(a)icmf.inf.cu wrote: > > > > > > I suppose we are all in agreement about the increase of U(r) with an > > > > > increase of r. Has U(r) a finite maximal limit value when r tends to > > > > > infinite? In case of positive answer, which is that maximal value? > > > > > You may have heard in freshman physics that the zero point of > > > > potential is physically arbitary. In all interactions, the only thing > > > > that is important is the *change* in potential energy between initial > > > > and final states, and that number is independent of the overall scale. > > > > Well, you dont answer my question, but what you say is compatible > > > with an infinite value for U(r) when r tends to infinite (any > > > arbitrary additive constant doesnt change the infinite). > > > Read what I wrote. U(r)=0 is quite finite. > > I dont understand your comment. When you write U(r)=0 you are only > assigning to U(r) the finite value 0 at some arbitrary r. Yes, and for example, it is often customary to set U(r)=0 when r=infinite. > What > relation do you establish between this and my question (not answered > by you yet) about if exist or not a finite maximal limit value for > U(r) when r tends to infinite? Now do you see? Have you NEVER studied out of a freshman physics text? > My last comment is related with the > fact that if any finite value is selected for the arbitrary r, this is > compatible with an infinite value for U(r) when r tends to infinite > (and not compatible if the arbitrary r is infinite). > > > > > > > > > > Anyway, I > > > consider more interesting the other alternative with a finite maximal > > > limit value. I just address it in an answer to dlzc (David) in this > > > same thread. I consider adequate to refer you to it, instead of > > > repeating here my analysis. > > > > > It is frequently customary to put U(r=infinity) = 0, so that all > > > > values of U(r) for finite r are negative. But this by no means > > > > required and many problems are more convenient to solve with a > > > > completely different choice. > > > > > PD > > > > RVHG (Rafael Valls Hidalgo-Gato) > > RVHG (Rafael Valls Hidalgo-Gato)- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: Dono. on 23 Jul 2010 11:41 On Jul 23, 6:40 am, PD <thedraperfam...(a)gmail.com> wrote: > On Jul 23, 7:25 am, va...(a)icmf.inf.cu wrote: > > > > > On 22 jul, 13:58, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Jul 19, 4:56 pm, va...(a)icmf.inf.cu wrote: > > > > > On 19 jul, 13:59, PD <thedraperfam...(a)gmail.com> wrote:> On Jul 16, 2:16 pm, va...(a)icmf.inf.cu wrote: > > > > > > > I suppose we are all in agreement about the increase of U(r) with an > > > > > > increase of r. Has U(r) a finite maximal limit value when r tends to > > > > > > infinite? In case of positive answer, which is that maximal value? > > > > > > You may have heard in freshman physics that the zero point of > > > > > potential is physically arbitary. In all interactions, the only thing > > > > > that is important is the *change* in potential energy between initial > > > > > and final states, and that number is independent of the overall scale. > > > > > Well, you dont answer my question, but what you say is compatible > > > > with an infinite value for U(r) when r tends to infinite (any > > > > arbitrary additive constant doesnt change the infinite). > > > > Read what I wrote. U(r)=0 is quite finite. > > > I dont understand your comment. When you write U(r)=0 you are only > > assigning to U(r) the finite value 0 at some arbitrary r. > > Yes, and for example, it is often customary to set U(r)=0 when > r=infinite. > > > What > > relation do you establish between this and my question (not answered > > by you yet) about if exist or not a finite maximal limit value for > > U(r) when r tends to infinite? > > Now do you see? > > Have you NEVER studied out of a freshman physics text? > He has no books, the only thing he has in Cuba is the free paper from 1905. This is all he can study.
From: valls on 23 Jul 2010 14:24
On 23 jul, 08:40, PD <thedraperfam...(a)gmail.com> wrote: > On Jul 23, 7:25 am, va...(a)icmf.inf.cu wrote: > > > > > > > On 22 jul, 13:58, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Jul 19, 4:56 pm, va...(a)icmf.inf.cu wrote: > > > > > On 19 jul, 13:59, PD <thedraperfam...(a)gmail.com> wrote:> On Jul 16, 2:16 pm, va...(a)icmf.inf.cu wrote: > > > > > > > I suppose we are all in agreement about the increase of U(r) with an > > > > > > increase of r. Has U(r) a finite maximal limit value when r tends to > > > > > > infinite? In case of positive answer, which is that maximal value? > > > > > > You may have heard in freshman physics that the zero point of > > > > > potential is physically arbitary. In all interactions, the only thing > > > > > that is important is the *change* in potential energy between initial > > > > > and final states, and that number is independent of the overall scale. > > > > > Well, you dont answer my question, but what you say is compatible > > > > with an infinite value for U(r) when r tends to infinite (any > > > > arbitrary additive constant doesnt change the infinite). > > > > Read what I wrote. U(r)=0 is quite finite. > > > I dont understand your comment. When you write U(r)=0 you are only > > assigning to U(r) the finite value 0 at some arbitrary r. > > Yes, and for example, it is often customary to set U(r)=0 when > r=infinite. > > > What > > relation do you establish between this and my question (not answered > > by you yet) about if exist or not a finite maximal limit value for > > U(r) when r tends to infinite? > > Now do you see? > > Have you NEVER studied out of a freshman physics text? > I continue without seeing an answer from you to my original questions opening this thread. To say that it is often customary to set U(r)=0 when r=infinite is not an answer at all. You say in a previous post that to put U(r)=0 when r=infinite is only a choice among others. If we set per example U(1)=0, that says nothing about the value of U(r) when r=infinite. Is so difficult to you to answer my original questions? If following you, this can be found in a freshman physics text, what excuse has you to not put your answers here? I showed you already the way to know my own ones. > > > > My last comment is related with the > > fact that if any finite value is selected for the arbitrary r, this is > > compatible with an infinite value for U(r) when r tends to infinite > > (and not compatible if the arbitrary r is infinite). > > > > > Anyway, I > > > > consider more interesting the other alternative with a finite maximal > > > > limit value. I just address it in an answer to dlzc (David) in this > > > > same thread. I consider adequate to refer you to it, instead of > > > > repeating here my analysis. > > > > > > It is frequently customary to put U(r=infinity) = 0, so that all > > > > > values of U(r) for finite r are negative. But this by no means > > > > > required and many problems are more convenient to solve with a > > > > > completely different choice. > > > > > > PD > > > > > RVHG (Rafael Valls Hidalgo-Gato) > > > RVHG (Rafael Valls Hidalgo-Gato RVHG (Rafael Valls Hidalgo-Gato) |