We have seen, throughout this site, that modern theoretical physics, physics post 1900, is badly flawed.
It is therefore fundamentally important to examine where these ideas came from, and why the problematic conclusions reached were premature.
The basis of modern scientific method in causal reasoning and the search for simplicity in physical explanations is detailed here.
The basis for modern physics theory lies in the failure of the idea of a background ether, and is detailed here.
The failure of the ether precipitated modern theory. The failure of the ether was both observational and theoretical. The key observation was by Michelson, detailed here, and discussed on this page, and the key theoretical failure was that of Maxwell, detailed below, and re-examined here.
The purpose of this page is to summarise the work and findings of Michelson and Maxwell and to demonstrate why the conclusions that were drawn were not the only ones possible, and to see what other options were - and are - available.
Nineteenth century understanding
The previous assumption, prior to 1900, was that light is a wave in a yet-to-be-discovered background. Light had been demonstrated by Huygens, Young and Fresnel, in particular, to have all of the properties of a wave, and this is detailed here. Since a wave is a disturbance in some underlying substance, a yet-to-be-discovered background was assumed and called the ether, and physics made serious attempts to discover its existence and its nature.
Together with respected research chemist Edward Morley, Albert Michelson set out to demonstrate that the Earth was moving through a static ether which was the medium through which light moved, and against which the speed of light was to be measured. This famously and spectacularly failed, as is detailed here.
Two alternatives were suggested, but neither found favour.
One was that the Earth dragged the ether along with it. The word often used is ‘entrained’.
This was not so far-fetched, as Fizeau (1851) had earlier shown that light travelling through moving water acts as if the light medium is being partially (about 50%) dragged along with the water. Fizeau’s remarkable finding was complicated by the observation of stellar aberration (Bradley, 1725) where the positions of stars are displaced (apparently displaced) by the motion of the Earth. If we think of the telescope as in motion, then this will affect, in both particle and wave models, the direction the light appears to have come from. When the telescope is filled with water (Airy, 1871), the effects become mixed.
As an explanation of Michelson, ether entrainment was unattractive. How could we measure it, beyond the failure of Michelson? And how much entrainment could we assume? If the background medium is invisible to us, and additionally in motion that we cannot determine, then it is an unattractive proposition as a basis for theory: we have no coherent or detailed description, and the prospect of developing a mathematical model is close to zero.
Nevertheless, when the replacement principle of relativity has failed in relation to timekeeping, is unnecessary in quantum theory and is abandoned by gravitational theory, it is heartening to know that there is an alternative.
The second alternative was that our attempts to find the ether were being undermined by a physical effect known as the Lorentz-Fitzgerald contraction. This idea, suggested by Fitzgerald (1889) and Lorentz (1892), is that material bodies are affected by their motion through the ether so as to be shortened, and that this shortening is of just the right amount to offset exactly the effect that Michelson was hoping to observe.
This was an ad hoc explanation in a period before ad hoc explanations became the norm in physics, and did not find favour.
James Clerk Maxwell provided a comprehensive analysis of electromagnetism, resulting in a definitive set of equations. Along the way, he described electromagnetic effects as forms of motion in a background medium, and demonstrated that this was the same as the luminiferous or light medium by deriving the speed of light from physical considerations and electromagnetic formulae and constants.
This appeared to support strongly the ether hypothesis.
However, Maxwell’s physical model was conflicted. His starting point for magnetism was that it was simply a bundle of microscopic vortices. This worked well, but required a fluidic background ether. In contrast, two later elements in his physical description suggested a solid background. These were the ‘displacement current’, described as a ‘strain’, and his conclusion that light was a transverse wave, which also appeared to require a solid ether.
Further details of Maxwell’s analysis, together with a tentative reinterpretation of his conclusions is provided here.
The rejection of the ether constituted a rejection of any physical interpretation of light as a wave. In its place, the following ideas found favour:
Everything is relative
Light is a particle
Light travels at the same constant speed for all observers.
These appeared at the time to have the potential to solve the serious problems that existed in the wake of the theoretical analysis of Maxwell and the experimental observations of Michelson.
The problems with each of these ideas are discussed throughout this site. However, the most serious problem for physics in the century since is that this also required the abandonment of the importance of causality, the central position of cause-and-effect thinking and analysis in physical science.
Advantages of reasoning deterministically
When causality becomes an optional component of theory, then theory is at risk of becoming contradictory, conflicted, incoherent and bizarre. These central but unscientific features of modern physics are illustrated and discussed throughout these pages, and this is a key message of this site. If we are to arrest this descent of theoretical physics into intellectual chaos, then it is important to understand how and why this has occurred. This is important epistemologically, in the understanding of the foundations of knowledge.
Not every scientist keeps deterministic reasoning central to her or his activities at all times. In any science there is – of should be – a mixture of skills and activities. But it is when a causal explanation is discovered that we all feel that the science makes sense, and it has a number of other benefits.
Max Planck received a Nobel Prize for his mathematical modelling of light emission and absorption, but wanted more from the theory:
‘But even if the radiation formula should prove to be absolutely accurate it would after all be only an interpolation formula found by happy guesswork, and would thus leave one rather unsatisfied. I was, therefore, from the day of its origination, occupied with the task of giving it a real physical meaning’i.
Poincaré put it as follows:
‘We cannot be satisfied with formulae that are merely placed side by side and agree only by a lucky chance; these formulae must, as it were, interlock. The mind will consent only when it sees reason for the agreement, and when this agreement even seems to be predictable.’ii
The two most impressive theories in science are the explanation of evolution by the means of natural selection provided by Darwin, and the explanation of geological processes in the motion of tectonic plates provided by those who came after Wegener.
An explanation has clear pedagogic benefits, and both of these theories are available in picture books for ten-year-olds, but an understanding of how and why these processes occur does more than merely satisfy the human mind.
Causal explanations such as these provide an intellectual structure that powerfully binds together a huge amount of data, and makes that data much easier to remember and codify.
But perhaps the greatest advantage is that it provides a coherent model across the subject matter, and one that can be doubted and interrogated, until it is right. We can be much more confident of a causal, determinist model that has survived interrogation than an acausal one. This is why biologists and Earth scientists are more confident of their models than physicists are. The latter speak of models and the mutability of knowledge, while the former more often speak of understanding nature.
Another advantage of having a model that offers the details of a physical mechanism is that each part of that explanation can itself be interrogated, and used to generate further experiment and observation, to challenge or refine the model provided.
Cause and effect analysis and modelling can be prodded until it is got right. It binds theory together, thereby keeping it simple, and this keeps it on the rails. A simple, coherent, determinist theory can be checked in more ways by more people. New suggestions have a much shorter shelf life before they are abandoned or incorporated. In physics, those theories sit around as theoretic noise.
These advantages of cause and effect explanation in science are very far from trivial. With them in place, we see science becoming confident, and going from strength to strength, as in modern biology. Without them, we see modern physics becoming defensive, often bizarre, and increasingly unscientific.
There is a reason why modern physics has become little more than one faddy new theory after another, reminiscent of sightings of the Loch Ness Monster, and the reason is this failure of deterministic understanding and its consequent rejection.
The strongest reason for concluding that the rejection of wave light and with it causality was premature is that it has turned a once respectable science into inconsistent, unintelligible mush. This devastating conclusion is only established by examining each of the theories and all of the options. Only then do we see that nothing works and become aware of the sheer volume and depth of the problems that have been created, including a widespread derogation of proper scientific behaviour.
Even then, we need something further to conclude that physics took a wrong turn in 1905, and this is that there are other options that were rejected at the time. While these options were genuinely unattractive, for the reasons provided, they do still exist as potentially valid alternatives.
These alternatives will not be followed here. One alternative theorist who has followed them is Esau James, who can be found here. Mr James’ determination to reason deterministically is a key reason for selecting his work over others for inclusion on this site.
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i. Max Planck, 1858 – 1947, 1919 Nobel Prize address, The Origin and Development of the Quantum Theory.
ii. H Poincaré - The Dynamics of the Electron, Rend. Del Circ. Mat. Di Palermo 21 (1906) page 129