Particles vs Fields vs Standard Model

The Standard Model of particle physics describes atomic physics in terms of 

• fermions as matter particles like electrons and protons 
• bosons as force carriers like (massless) photons and gluons.

While matter particles as electrons and protons carrying charge intuitively appear to connect to some reality, the idea of photon as carrier of electromagnetic force is more difficult to grasp. In fact, in all of electromagnetics so well described by Maxwell's equations, photons as carrier of electromagnetic force do not appear. 

In particular the electric force appears as the gradient $\nabla\phi$ of an electric potential $\phi (x,t)$ as a continuous function or field depending on a Euclidean space coordinate $x$ and $t$ a time coordinate. 

Similarly, in Newtonian gravitation, the gravitational force appears as the gradient of a gravitational potential field. There is here no need to worry about a carrier of gravitational force in the form of some hypothetical particle named graviton, which has evaded all form of detection. 

In field theories there is thus no need to introduce particles as force carriers, since forces come out as gradients of fields. 

In particular, the idea of photon as carrier of electric force has no role to serve in electromagnetics described by Maxwell's equations. 

Confronted with this fact, a modern physicist would say that particle theory and field theory in fact are just the same with a particle simply a fluctuation of a field and so to say that the photon is the carrier of electric force makes perfect sense. 

In particular, modern physics insists that both blackbody radiation and the photoelectricity must be understood in terms of a stream of photons as particles of light, and then not in terms of fields even if particle and field is the same. 

Computational BlackBody Radiation offers an alternative Maxwellian field theory, where radiative heat transfer appears as a resonance phenomenon and photoelectricity is a threshold phenomenon, both free of particles.  

In summary, there does not seem to be any real need to view a photon to be a particle carrying electromagnetic force, and so the whole idea of fundamental particles as force carriers may lack sound reason. Yet it is a fundamental part of the Standard Model and so may be a suspect behind the crisis of modern physics witnessed by leading physicists.

Grand Unified Theory: 3 Attempts

Einstein spent the last half of his life searching for a unified field theory as an extension of his General Theory of Relativity GR from 1916 describing the force of gravitation as an effect of curved space-time, to cover  all fundamental forces including electromagnetic and weak/strong nuclear forces. But the basic idea of describing forces as effects of curved space-time did not show to be fruitful. That was the first attempt to create a Grand Unified Theory GUT.  

The next attempt initiated in the 1950s was to extend quantum mechanics/electromagnetics QM/EM to cover also gravitation in the form of quantum gravity, but has not led to success. 

Modern physicists thus confront the following failed attempts of forming a GUT:

• A1: Extend GR to include QM/EM.
• A2: Extend QM/EM to include gravitation.

The reason A1 fails is that curved space-time does not serve to describe QM/EM. The reason A2 fails is that standard QM as atomic physics microscopics is viewed to be fundamentally different from the macroscopic world of gravitation, thus with a glitch between microscopics and macroscopics.  

This leaves modern physics in a dead-lock of incompatible theories for microscopics and macroscopics, which is the root of the present crisis of modern physics witnessed by many including prominent physicists. 

Here RealQM may offer a way forward, because in RealQM the microscopics of atoms takes the same form as macroscopics as continuum models in 3d, as exposed in previous posts. This means that a GUT may be possible in the form of 

• A3: RealQM + EM + gravitation  

captured in the following mathematical models:

• RealQM: New Schrödinger equation in 3d.
• EM: Maxwell's equations 
• Newton's law of gravitation

which can freely be combined into a GUT without glitch. Here Einstein has no role to play and the right part of the above diagram is left out.

While A1 and A2 have already failed, A3 has not yet. Want to challenge? 

Why Not GUT/TOE as Newton+Maxwell+Schrödinger?

There is a Grand Unified Theory of physics GUT (or Theory of Everything TOE) in the form of Newton's Mechanics + Maxwell's Electromagnetics + Quantum Mechanics expressed as partial differential equations over continua of 3d Euclidean space coordinate systems and time:  

1. Newton's equations of macroscopic motion of matter/mass subject to gravitation.  
2. Maxwell's equations for light without mass/charge and matter with charge.
3. Schrödinger's equations for microscopics of electromagnetics.

But this form of GUT is rejected by modern physicists following Einstein in his pursuit of replacing Newton's Mechanics by his General Theory of Relativity GR from 1915 initiated by his Special Theory of Relativity SR from 1905. 

Einstein was driven by a fixed idea (strike of genius?) that physical laws must take the same form independent of the choice of coordinate system, named covariance. He found this to be the case for Maxwell's equations taking the same mathematical form under Lorentz transformations, but not Galilean transformations. Einstein observed the opposite to be true for Newton's equations and so, seemingly out of the blue, he decided that Newton's Mechanics had to be replaced by his new theory of relativistic mechanics in the form of SR/GR. This was a monumental proclamation which was for a long time met with much skepticism, but gradually through clever marketing has come to represent the major advancement offered by modern physics as opposed to classical Newtonian physics. 

Einstein’s leading idea that mathematical expressions (formulas, equations) of physical laws must literally letter by letter look the same in different coordinate systems, is absurd. It is the same as saying that there can be only one language word by word letter by letter, describing a common physical world. Of course the choice of coordinate system in general will affect the letters of the mathematical expression of a physical law. Nevertheless Einstein used his fixed idea to discriminate Newton’s equations because they changed form under Lorentz transformations. And after 50 years of brooding modern physicists jumped the band wagon against Newton. 

Critics point to the following consequences replacing Newton by Einstein/SR/GR:

• SR/GR is claimed to differ from Newton's Mechanics only in utterly extreme situations, such as black holes or space ships approaching the speed of light, so extreme that even SR/GR falls short.
• SR/GR is incompatible with quantum mechanics, and thus makes modern physics into non-physics without a GUT.
• SR/GR is understood by very few, if any, and so its practise is sparse, while Newton's Mechanics is understood and practised by many.    
• Presented experimental evidence concern detection of extremely weak signals from extremely massive violent large scale cosmological phenomena, such as gravitational waves from the merger of two black holes in the LIGO experiment.

In this light the following questions come up: 

• Is it necessary to replace Newton by Einstein? 
• Is GUT in the form of Newton+Maxwell+Schrödinger impossible? 

A modern physicist would answer Yes! to both questions, even at the cost of giving up the idea of GUT. A modern physicist will then have to motivate why Newton must be replaced by Einstein,  even if it means a collapse of physics as science. 

Einstein is famous for his "thought experiments" as a chain of arguments within a theory such as SR, twisted to serve as external/experimental confirmation of the correctness of the theory. In particular, the constancy of the speed of light (in vacuum) is an agreement resulting from the thought experiment of agreeing to use the Lorentz transformation, which allows SR to prove itself to be true or allowing Einstein with 100% confidence to proclaim that nothing can prove SR to not be true!  Because it is an agreement! 

But agreements can be broken, and what happens if the agreement to coordinate observations in different inertial systems according to the Lorentz transformation, is given up? What compels observers to follow such a dictate?