Imports
/- Copyright (c) 2025 Joseph Tooby-Smith. All rights reserved. Released under Apache 2.0 license as described in the file LICENSE. Authors: Joseph Tooby-Smith -/ module public import Physlib.Electromagnetism.Distributional.Dynamics.IsExtrema public import Physlib.SpaceAndTime.Space.Norm.Basic public import Physlib.SpaceAndTime.Space.Translations

The electrostatics of a stationary point particle in 1d

i. Overview

In this module we give the electromagnetic properties of a point particle sitting at the origin in 1d space.

ii. Key results

    oneDimPointParticle : The electromagnetic potential of a point particle stationary at the origin of 1d space.

    oneDimPointParticle_isExterma : The electric field of a point particle stationary at the origin of 1d space satisfies Maxwell's equations

iii. Table of contents

    A. The current density

    B. The Potentials

      B.1. The electromagnetic potential

      B.2. The vector potential is zero

      B.3. The scalar potential

    C. The electric field

      C.1. The time derivative of the electric field

    D. The magnetic field

    E. Maxwell's equations

iv. References

@[expose] public section

A. The current density

c:SpeedOfLightq:โ„rโ‚€:Space 1โŠข (SpaceTime.distTimeSlice c).symm (constantTime ((c.val * q) โ€ข diracDelta' โ„ rโ‚€ (Lorentz.Vector.basis (Sum.inl 0)))) = (SpaceTime.distTimeSlice c).symm (constantTime ((distTranslate (basis.repr rโ‚€)) ((c.val * q) โ€ข diracDelta' โ„ 0 (Lorentz.Vector.basis (Sum.inl 0))))) c:SpeedOfLightq:โ„rโ‚€:Space 1โŠข (c.val * q) โ€ข diracDelta' โ„ rโ‚€ (Lorentz.Vector.basis (Sum.inl 0)) = (distTranslate (basis.repr rโ‚€)) ((c.val * q) โ€ข diracDelta' โ„ 0 (Lorentz.Vector.basis (Sum.inl 0))) c:SpeedOfLightq:โ„rโ‚€:Space 1ฮท:๐“ข(Space 1, โ„)iโœ:Fin 1 โŠ• Fin 1โŠข ((c.val * q) โ€ข diracDelta' โ„ rโ‚€ (Lorentz.Vector.basis (Sum.inl 0))) ฮท iโœ = ((distTranslate (basis.repr rโ‚€)) ((c.val * q) โ€ข diracDelta' โ„ 0 (Lorentz.Vector.basis (Sum.inl 0)))) ฮท iโœ All goals completed! ๐Ÿ™@[simp] lemma oneDimPointParticleCurrentDensity_currentDensity (c : SpeedOfLight) (q : โ„) (rโ‚€ : Space 1) : (oneDimPointParticleCurrentDensity c q rโ‚€).currentDensity c = 0 := c:SpeedOfLightq:โ„rโ‚€:Space 1โŠข (DistLorentzCurrentDensity.currentDensity c) (oneDimPointParticleCurrentDensity c q rโ‚€) = 0 c:SpeedOfLightq:โ„rโ‚€:Space 1ฮต:๐“ข(Time ร— Space 1, โ„)i:Fin 1โŠข (((DistLorentzCurrentDensity.currentDensity c) (oneDimPointParticleCurrentDensity c q rโ‚€)) ฮต).ofLp i = (0 ฮต).ofLp i All goals completed! ๐Ÿ™@[simp] lemma oneDimPointParticleCurrentDensity_chargeDensity (c : SpeedOfLight) (q : โ„) (rโ‚€ : Space 1) : (oneDimPointParticleCurrentDensity c q rโ‚€).chargeDensity c = constantTime (q โ€ข diracDelta โ„ rโ‚€) := c:SpeedOfLightq:โ„rโ‚€:Space 1โŠข (DistLorentzCurrentDensity.chargeDensity c) (oneDimPointParticleCurrentDensity c q rโ‚€) = constantTime (q โ€ข diracDelta โ„ rโ‚€) c:SpeedOfLightq:โ„rโ‚€:Space 1ฮต:๐“ข(Time ร— Space 1, โ„)โŠข ((DistLorentzCurrentDensity.chargeDensity c) (oneDimPointParticleCurrentDensity c q rโ‚€)) ฮต = (constantTime (q โ€ข diracDelta โ„ rโ‚€)) ฮต c:SpeedOfLightq:โ„rโ‚€:Space 1ฮต:๐“ข(Time ร— Space 1, โ„)โŠข c.val * q * (c.valโปยน * (timeIntegralSchwartz ฮต) rโ‚€) = q * (timeIntegralSchwartz ฮต) rโ‚€ All goals completed! ๐Ÿ™

B. The Potentials

B.1. The electromagnetic potential

๐“•:FreeSpaceq:โ„rโ‚€:Space 1โŠข (SpaceTime.distTimeSlice ๐“•.c).symm (constantTime (distOfFunction (fun x => (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * โ€–x - rโ‚€โ€–) โ€ข Lorentz.Vector.basis (Sum.inl 0)) โ‹ฏ)) = (SpaceTime.distTimeSlice ๐“•.c).symm (constantTime ((distTranslate (basis.repr rโ‚€)) (distOfFunction (fun x => (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * โ€–xโ€–) โ€ข Lorentz.Vector.basis (Sum.inl 0)) โ‹ฏ))) ๐“•:FreeSpaceq:โ„rโ‚€:Space 1โŠข distOfFunction (fun x => (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * โ€–x - rโ‚€โ€–) โ€ข Lorentz.Vector.basis (Sum.inl 0)) โ‹ฏ = (distTranslate (basis.repr rโ‚€)) (distOfFunction (fun x => (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * โ€–xโ€–) โ€ข Lorentz.Vector.basis (Sum.inl 0)) โ‹ฏ) ๐“•:FreeSpaceq:โ„rโ‚€:Space 1ฮท:๐“ข(Space 1, โ„)iโœ:Fin 1 โŠ• Fin 1โŠข (distOfFunction (fun x => (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * โ€–x - rโ‚€โ€–) โ€ข Lorentz.Vector.basis (Sum.inl 0)) โ‹ฏ) ฮท iโœ = ((distTranslate (basis.repr rโ‚€)) (distOfFunction (fun x => (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * โ€–xโ€–) โ€ข Lorentz.Vector.basis (Sum.inl 0)) โ‹ฏ)) ฮท iโœ All goals completed! ๐Ÿ™/- ### B.2. The vector potential is zero -/ @[simp] lemma oneDimPointParticle_vectorPotential (๐“• : FreeSpace) (q : โ„) (rโ‚€ : Space 1) : (oneDimPointParticle ๐“• q rโ‚€).vectorPotential ๐“•.c = 0 := ๐“•:FreeSpaceq:โ„rโ‚€:Space 1โŠข (vectorPotential ๐“•.c) (oneDimPointParticle ๐“• q rโ‚€) = 0 ๐“•:FreeSpaceq:โ„rโ‚€:Space 1ฮต:๐“ข(Time ร— Space 1, โ„)i:Fin 1โŠข (((vectorPotential ๐“•.c) (oneDimPointParticle ๐“• q rโ‚€)) ฮต).ofLp i = (0 ฮต).ofLp i All goals completed! ๐Ÿ™

B.3. The scalar potential

๐“•:FreeSpaceq:โ„rโ‚€:Space 1ฮต:๐“ข(Time ร— Space 1, โ„)โŠข ๐“•.c.val * ((-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2) โ€ข distOfFunction (fun x => โ€–x - rโ‚€โ€–) โ‹ฏ) (timeIntegralSchwartz ฮต) = (-((q * ๐“•.ฮผโ‚€ * ๐“•.c.val ^ 2 / 2) โ€ข distOfFunction (fun x => โ€–x - rโ‚€โ€–) โ‹ฏ)) (timeIntegralSchwartz ฮต) ๐“•:FreeSpaceq:โ„rโ‚€:Space 1ฮต:๐“ข(Time ร— Space 1, โ„)โŠข ๐“•.c.val * (-(q * ๐“•.ฮผโ‚€ * ๐“•.c.val) / 2 * (distOfFunction (fun x => โ€–x - rโ‚€โ€–) โ‹ฏ) (timeIntegralSchwartz ฮต)) = -(q * ๐“•.ฮผโ‚€ * ๐“•.c.val ^ 2 / 2 * (distOfFunction (fun x => โ€–x - rโ‚€โ€–) โ‹ฏ) (timeIntegralSchwartz ฮต)) All goals completed! ๐Ÿ™

C. The electric field

๐“•:FreeSpaceq:โ„rโ‚€:Space 1h1:โˆ‡แตˆ (distOfFunction (fun x => โ€–xโ€–) โ‹ฏ) = distOfFunction (fun x => โ€–xโ€–โปยน โ€ข basis.repr x) โ‹ฏโŠข (distTranslate (basis.repr rโ‚€)) (โˆ‡แตˆ (distOfFunction (fun x => โ€–xโ€–) โ‹ฏ)) = distOfFunction (fun x => โ€–x - rโ‚€โ€–โปยน โ€ข basis.repr (x - rโ‚€)) โ‹ฏ All goals completed! ๐Ÿ™

C.1. The time derivative of the electric field

๐“•:FreeSpaceq:โ„rโ‚€:Space 1โŠข (q * ๐“•.ฮผโ‚€ * ๐“•.c.val ^ 2 / 2) โ€ข 0 = 0 All goals completed! ๐Ÿ™

D. The magnetic field

lemma oneDimPointParticle_magneticFieldMatrix (q : โ„) (rโ‚€ : Space 1) : (oneDimPointParticle ๐“• q rโ‚€).magneticFieldMatrix ๐“•.c = 0 := ๐“•:FreeSpaceq:โ„rโ‚€:Space 1โŠข (magneticFieldMatrix ๐“•.c) (oneDimPointParticle ๐“• q rโ‚€) = 0 All goals completed! ๐Ÿ™

E. Maxwell's equations

๐“•:FreeSpaceq:โ„rโ‚€:Space 1h1:distDiv (distOfFunction (fun x => โ€–xโ€–โปยน โ€ข basis.repr x) โ‹ฏ) = volume.real (Metric.ball 0 1) โ€ข diracDelta โ„ 0โŠข (ENNReal.ofReal 1 ^ Module.finrank โ„ (Space 1) * ENNReal.ofReal (Real.pi ^ 0 * 2 ^ (0 + 1) / โ†‘(Module.finrank โ„ (Space 1)).doubleFactorial)).toReal = 2๐“•:FreeSpaceq:โ„rโ‚€:Space 1h1:distDiv (distOfFunction (fun x => โ€–xโ€–โปยน โ€ข basis.repr x) โ‹ฏ) = volume.real (Metric.ball 0 1) โ€ข diracDelta โ„ 0โŠข Module.finrank โ„ (Space 1) = 2 * 0 + 1 ๐“•:FreeSpaceq:โ„rโ‚€:Space 1h1:distDiv (distOfFunction (fun x => โ€–xโ€–โปยน โ€ข basis.repr x) โ‹ฏ) = volume.real (Metric.ball 0 1) โ€ข diracDelta โ„ 0โŠข (ENNReal.ofReal 1 ^ Module.finrank โ„ (Space 1) * ENNReal.ofReal (Real.pi ^ 0 * 2 ^ (0 + 1) / โ†‘(Module.finrank โ„ (Space 1)).doubleFactorial)).toReal = 2 All goals completed! ๐Ÿ™ ๐“•:FreeSpaceq:โ„rโ‚€:Space 1h1:distDiv (distOfFunction (fun x => โ€–xโ€–โปยน โ€ข basis.repr x) โ‹ฏ) = volume.real (Metric.ball 0 1) โ€ข diracDelta โ„ 0โŠข Module.finrank โ„ (Space 1) = 2 * 0 + 1 All goals completed! ๐Ÿ™๐“•:FreeSpaceq:โ„rโ‚€:Space 1ฮต:๐“ข(SpaceTime 1, โ„)i:Fin 1โŠข ๐“•.ฮผโ‚€โปยน * (1 / ๐“•.c.val ^ 2 * (((SpaceTime.distTimeSlice ๐“•.c).symm (distTimeDeriv ((electricField ๐“•.c) (oneDimPointParticle ๐“• q rโ‚€)))) ฮต).ofLp i - โˆ‘ j, (((PiLp.basisFun 2 โ„ (Fin 1)).tensorProduct (PiLp.basisFun 2 โ„ (Fin 1))).repr (((SpaceTime.distTimeSlice ๐“•.c).symm ((distSpaceDeriv j) ((magneticFieldMatrix ๐“•.c) (oneDimPointParticle ๐“• q rโ‚€)))) ฮต)) (j, i)) + (((SpaceTime.distTimeSlice ๐“•.c).symm ((DistLorentzCurrentDensity.currentDensity ๐“•.c) (oneDimPointParticleCurrentDensity ๐“•.c q rโ‚€))) ฮต).ofLp i = 0 All goals completed! ๐Ÿ™