Mobile object needs power. Well-known, speed produces acceleration along with time change; Consequently momentum changes along with time, generation force. Electromagnetism system is effective also, for instance QE of electric field force, qv X B of magnetic field force. The momentum that generates these force correspondence calls mechanical momentum. But, this machinery momentum is not conservation quantity, be like an electron – the momentum of the electron in electromagnetism coupling system also is not conservation the amount is same.

 

If regard electromagnetism field or light as particle, be like a bullet, it also can deliver force to go up to the object. When electromagnetism field experiences specular reflection, because of the change of speed direction, deliver momentum lens range necessarily, generation tries to move the force of lens face. If a bundle of light is absorbed by the object, also momentum delivers this object. If the object is enough small, enough light, this kind of force is possible mobile object. The momentum that this kind of field generates, should have some kind of connection with the particle sex of electromagnetism field. According to hypothesis of heart cloth Luo Yi, momentum P = ? K = ? ω/c = E/c. If keep energy into power and the product with differential time, power is written into can shed density E X H and area small yuan of product of DS, time is written into the distance small C of yuan of the velocity of light on Dl comparing, get E X H / C2 of expression of field momentum density finally. And field momentum adds mechanical momentum is quantity of a conservation, the power that they produce jointly, tensor of usable maxwell stress will calculate. This also is the most commonly used calculation method in smooth force.

 

If further development analyses the expression of a momentum, will become very interesting. In this expression, if decompose electric field fore-and-aft heft (area of near field, active) with transverse heft (far field, passive area) , of fore-and-aft heft correspondence, ∫v El X H / C2 DV, change brief hind it is quanta unexpectedly mechanical in corresponding field momentum QA. This momentum QA and electronic momentum Mv add in is conservation quantity, after be being changed by quanta namely criterion momentum functor. And the transverse heft that remain, ∫v Et X H / C2 DV, continue to decompose, can divide two again, one is spin momentum, another is orbit momentum. Former concern with the polarization of electromagnetic wave, round polarization contains spin angular momentum. Concern before the wave of latter and electromagnetic wave, vortex electromagnetic wave (if gauss pulls lid Er beam) contain orbit angular momentum. The electromagnetic wave that contains spin angular momentum and orbit angular momentum can produce moment, rotate particle. The expression of the spin in electromagnetism field and orbit angular momentum and electric subsystem agree breathtakingly, the Pauli matrix that became 3×3 besides spin functor just. Orbit momentum density and direct ratio of expression of density of orbit angular momentum at? E | – I? ∇| E? And? E | R X (-i? ∇) | E? , this accords with the form of angular momentum functor apparently, l=r X P= R X (-i? ∇) .

 

If make expression of airspace of orbit angular momentum,Fourier alternates, receive K region expression, the orbit momentum density of K region is not other, be the definition of Berry Connection. Close Berry Connection method integral gets Berry Phase along some, except get Chen Shu with 2π . To the vortex electromagnetic wave of round polarization, the spin that this old number contacts electromagnetic wave (σ= -1, 1) with orbit (L = 1, – 1, 2, – 2, … ) develop attacks charge counts the sum. Although vortex wave is in free space communication,experience mode strings together the worry of effect of diverge of faze, beam, much diameter, it remains a very stable beam, disturb smally won’t change its develop to attack property. And understanding vortex electromagnetic wave and develop attack the connection between dielectric, the develop that how vortex electromagnetic wave digs in reaching communication of orbit angular momentum attacks property, it is the task that is worth thorough exploration. And have develop to attack from physical angle stable vortex electromagnetic wave, the actual application on communication project still requires great effort. “Even Though Many Problems Are A ‘done Deal’In The Physics Community, they Are Not A ‘done Deal’In An Engineering Community. Much Blood, sweat, and Tears Are Needed. ”

 

Afore-mentioned viewpoints, be author individual think and experience, do not represent correct and strict electromagnetism theory. Welcome everybody to criticize point out mistakes so that they can be corrected! The maths of the article is formulary (did not publish) , see following pictures.

 

 

 

 

 

The article is reprinted from electromagnetism compatible EMC.