I believe that we have no quarrel with applied as opposed to theoretical physics, either in the definition of concepts like kinetic energy or potential, or in the measurements we make. The question about theoretical physics, however, is a deep one. What is it in relation to 'reality'? Do we really need it, or is it a luxury, a dream, or simply an abstract mathematical exercise? In a sense it is where imagination, or myth takes us - beyond the realm of the observable, beyond empirical knowledge. In that sense 'Theoretical Physics' is mostly NOT physics, it is myth or speculation.
This addendum should be treated as an exercise, or a supplement, to the more rigorous and serious analysis and critique of contemporary theoretical physics presented in the previous chapters of this web site. Here the purpose is to provoke and to question, in a lighter vein, the beliefs, and the tacit assumptions that characterize contemporary theoretical physics.
Wikipedia has this to say about Theoretical Physics:
"Theoretical physics is a branch of physics which employs mathematical models and abstractions of physics in an attempt to explain natural phenomena. Its central core is mathematical physics, though other conceptual techniques are also used. The goal is to rationalize, explain and predict physical phenomena."
I believe this tells us little about physics and nothing as to how theory relates to whatever physics is about.
Let me try a different approach: physics, at its most primitive, is about matter in motion – it could be an automobile on a street, a bullet fired from a gun, a stone rolling down a hill, a head of steam, a plane flying through the air, a rocket ship, a planet in motion around a star, or a burst of light from the explosion of a star. But physics is not concerned with a runner in a race, or an insect crawling up a wall, or a bee in flight. If the motion is associated with other than inanimate objects it is not physics – unless perhaps they are dead and lifeless entities that are not self propelled.
So that is what physics, at bottom, is about - if I can be permitted such a simplistic view for the purpose of this discussion. If we now look at typical observations, for example rocks, or other objects thrown down from the tower of Pisa, we can discover, empirically, some facts about motion: that all objects accelerate on the way down, with constant force or acceleration producing constant changes in velocity, not dependent on the size, weight, or type of material (ignoring of course friction or other second order effects). Theory enters when we generalize and quantify the character of the motion. When for example we assert that if the height from which objects are dropped increases, the rate of change of the velocity, the acceleration, will continue to be constant – without limit. We can’t prove this, but it is a convenient assumption – but it implies a Euclidean and open universe.
It would be foolish to assume that this ‘law’ can be extended to all speeds, for eventually we would exceed the speed of light, and in an open universe we could reach indefinitely, we could even say infinitely, large velocities!.
A fundamental difference between Newton and Einstein is this: In the Newtonian-Euclidean approach to theoretical physics we believe in the unlimited applicability of the law that constant force or acceleration produces constantly greater velocities - there is no upper bound. In the universe of Einstein there is a brick wall, the speed of light, c, that no particle of matter can penetrate or reach.
From Einstein’s view it follows that light, i.e., radiation, cannot be material (since, according to this view, radiation, in a vacuum, travels at exactly the velocity c regardless of its frequency or wavelength). It follows that we, (or rather Einstein) must develop a rationale for preventing matter from ever reaching the velocity c. This leads Einstein to such results as the slowing of time, the distortion of space and the increasing of the mass of particles of matter as they reach for greater speed (the mass must necessarily approach infinity at the speed of light), all of which are required to support the existence of this ‘brick wall’.
What do we do with this dilemma? Newtonian physics cannot be accepted without restrictions and qualifications, and contemporary theoretical physics is based on contradictions, ambiguities, and false premises. That is the sad truth, and the only way out is to look for a possible middle ground.
What would be nice is a new or modified theory that does no major violence to our beliefs in the character of space and time. We have no, or almost no experimental evidence that lets us decide between the above two alternatives. It is to the region beyond empirical evidence where most theoretical physics takes us.
The approach and the assumptions of Einstein and Newton are in opposition, but there may be a middle way. For example, if acceleration becomes gradually ineffectual as speed increases, or if the properties of matter change with speed, (for example the charge of elementary particles), we may not have a brick wall but a soft cushion. Instead of deforming time, space, and mass, we could modify force or acceleration, and ‘force’ it to become weaker as velocity increases.
Or, if the universe is ‘closed’, that is to say if what we view as the parabolic paths of heavenly entities are, in reality, very large ellipses than we are saved from the problem of an open universe. A collision takes care of preventing infinite speeds and, where there is no collision, there is no problem with continual acceleration in an elliptical path, such as that of the earth around the sun. So if we can come to believe that, like comets, all heavenly bodies will some day, in the indefinite future, return, (and so will photons) than we may not need the idea of a brick wall, with the distortions of space and time that Special Relativity brings with it, in order to achieve a closed universe.
But without the brick wall there is no guide, at present, to decide which ‘geometry’ is correct. Einstein’s thinking is directed at modifying Euclidian geometry to accommodate Relativity and the ‘brick wall’, i.e. the speed of light. Without the brick wall we are a little lost. A closed universe would be nice – but just how it would look is hard, or impossible, at the present state of development of theoretical physics, to decide.
But here are some of the areas we need to look at.
There are many problems connected with the data, the interpretation and meaning of ‘red shift’ and the inferences drawn. As pointed out in the previous chapters, a recalculation of the Doppler effect, without invoking Special Relativity, indicates that the earliest and most distant supernova point to stars that did not recede with as large a velocity as has been generally inferred. A correction, based on using the ‘correct’ Doppler equation, refutes the claim that the universe is so large, so old, and so rarefied that it must necessarily go on expanding. A steady state, or a cyclic universe, is ever so much more appealing – and ever so much more likely.
What must be made clear is that the kind of reddening we are concerned with in the Doppler shift is not a mere increase in the wavelength of light. There can be reddening due to the scattering of blue light, the evening sun is such an example, but that is not a Doppler effect. There may be other factors that produce an increase in wavelength –e.g. light slowing down in a denser medium such as glass. But if we look at the spectrum of hydrogen, and consider,for example, the Balmer series, (the visual frequencies that a hydrogen atom emits or absorbs) then a shift of the entire series, say a multiplication of the individual wavelengths by a factor 2, would signal a recession velocity equal to one-half the speed of light. By considering such a known group of lines, and using the correct Doppler formula, we can infer the correct ‘red shift’, the correct recession, and get a more appealing cosmology as the prize.
It has been suggested, by some, that the result of the M&M experiment can be understood using the Doppler effect. The approach to the Doppler effect using waves has contributed to confusion as to when such an effect can arise - whether one can deal with ‘compression’ or ‘expansion’ of waves without considering the movements of source or receiver. The M&M experiment can be thought of as taking place using two mountaintops. These mountains don’t move towards or away from each other. How can you possibly get a Doppler effect when there is no motion between source and receiver? The issue, in this case, is pure and simple: is there a carrier for the light, such as the air is for sound? And the answer of the M&M experiment, done over and over, is that no such parallel between sound and light can be found. There is no asymmetry, as in the case of sound and, of course, no Doppler effect,. Whatever we believe about a carrier of light is a matter of myth, not physics, but the Doppler effect can play no role in the theory since it does not exist in the M&M experiment.
But consider this: at a distance of one billion light years it would take over 100,000 years for a star to shift its position in the sky by one second of arc, even if it moves at the rate of one- half the speed of light.
We can’t, in our lifetime, or in the lifetime of humanity, detect any change in the tangential or transverse position of the 'fixed stars’. They 'appear' to be fixed – but we should realize that this is a myth, not a fact..
Fortunately, this is only the case for transverse movement. The radial movement, even though we can sometimes detect it only a billion years after it happened, can be detected by means of the Doppler effect. The movement away from us implies very large radial velocities, on the order of half the speed of light. This is no myth, and suggests that the tangential, or transverse, rate is probably of the same order of magnitude. Thus we can indirectly get from myth to probable fact.
What this line of reasoning does is to shed additional light on the detection and interpretation of supernova events. If, as is the case in the chapter on “Light,” we detect rings of radiation, whether at x-ray or radio frequencies, the rings must subtend a few degrees in order to be seen as rings. That in turn implies that the radiation from the matter corresponding to these rings must originate tens of millions of years after the matter was ejected in the seconds that the star exploded, if the supernova is a billion light years away. In such a case it would require that this matter, from which the circle of radiation originates, has an age of somewhere between one and on hundred million years, measured from the time of the explosion (depending on our assumption of the rate of travel of theses masses, say one tenth to one half the speed of light). No wonder that the light from the explosion itself is not seen in a picture showing the radiation from the ‘rings’ (remember these are not really rings, but simply the regions on a sphere from which the radiation reaches us at the same time). The radiation from the original explosion has passed long ago. And conversely if we see the light from a supernova explosion itself we can expect the ‘rings’ of radiation, from the matter ejected, to be seen somewhere in the distant future.
In the case of the supernova, SN1987A, that was first seen visually in February 1987, and which reached a peak in May, this explosion occurred about 170,000 light years away (almost ‘next door’ in comparison with the size of the universe). The difference in time of the visual radiation from beginning to end, less than one year, represents a difference in the velocity of light in the sixth’s decimal place! If matter, in the form of a shock wave, is ejected with a velocity of, say, .9c, we won’t see the radiation emitted from this cloud or sphere, as a ring, for between ten and one hundred years!
Electrons and protons can become excited and experience increases in energy. Electrons absorb photons and move to higher orbits around the nucleus of an atom. Photons can be deflected from their path. We can have Rayleigh and Mie scattering of visible radiation, for example, but in these processes the photons retain their identity, their color, or frequency, if you will. They endure.
But there is an exception – Raman scattering, discovered in the 1920’s:
According to Wikipedia:
"When light is scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering), such that the scattered photons have the same energy (frequency) and wavelength as the incident photons. However, a small fraction of the scattered light (approximately 1 in 10 million photons) is scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, the frequency of the incident photons."
What this means for photons is of great significance. Photons can, under some circumstances change their identity.
I had suspected this in the late 1950’s in my work and publications on the detection of light in photographic materials. In my work in the Physics Research Laboratory of Eastman Kodak I was investigating, theoretically, but also to some extent experimentally, the ‘noise’, i.e. the granularity, of photographic images. Photographic emulsions exposed to x-rays are ‘noisier’ than when exposed to visible light.
The reason is that in the visible region the photons are not energetic enough in themselves to produce the latent image that is subsequently developed. It takes several photons striking the same tiny region of Silver Bromide, within a short time, to produce the specs of silver that can then be amplified to become the photographic image. But x-rays, at shorter wavelengths, and higher frequencies, have enough energy that one such photon can produce several, often many silver specs near to each other. The good side of this is that it takes fewer photons to produce a visible image. The bad side is that because the silver specs are clustered, rather than purely random, the image is more granular, that is ‘noisier’, than a photograph made with visible light.
We don’t know what happens to the x-ray photon after it produces the first such silver spec. Some theorists (the Gurney-Mott theory) believe that an electron is generated and this electron produces several more silver specs in the vicinity of the first one. But it could also be that something like Raman scattering occurs. The x-ray photon loses some energy and has a slight decrease in its frequency, and this process continues until all the energy is used up, or the somewhat exhausted x-ray photon continues on its way after exiting the photographic plate.
In any case it appears that photons can change their identity, their frequency, that is to say, their color, under some circumstances. Unlike the case of the Doppler shift, which produces apparent, but NOT real shifts of frequency, either blue or red shifts, depending on whether source and receiver are approaching or separating, REAL shifts, that is changes in the identity of photons, can occur.
If we extrapolate the above lines of thought, it would provide us with a rationale for re-interpreting cloud and bubble chamber experiments. A particle, even if it has a lifetime of only one tenth of a billionth of a second, that has a mass about twice that of a proton, is hard to swallow. (Imagine its mass at a velocity of .95c, if its rest mass is twice that of a proton.)
Inferences about the mass of semi-stable particles are based, generally, on the values of e/m, and the conviction that e is constant. But any suggestion for revamping the conclusions of particle physicists as to the character, and existence, of the exotic particles that have been spawned in the second half of the twentieth century are sure to be met with stiff opposition. But the idea of losing charge, with increasing speed, of stable entities, could be an alternative to ‘new’ and ‘exotic’ short-lived entities.
The curved, or straight fragments of tracks in a bubble chamber, together with the conviction that the speed of light is constant, that Special Relative is sacred, and that mass increases with speed, rather than that charge decreases, that combination of facts and convictions is what constitutes particle physics. If it turns out that the number of entities in the stable continues to increase, or if the number and type of the attributes also grows beyond bounds, then there may be hope for a second look, by a new generation of physicists, at the basic convictions that have been questioned in this work.
That puzzle came back to me recently, together with the thought that under the conjectures developed here, blue light, having the shorter wavelength should have about twice the mass of red light – pure speculation on my part. If the interaction of light with the prism involves the interaction of masses it should be stronger for blue light then for red light. A grating, on the other hand, allows for interaction of waves, and this should favor red light, with its longer wavelength.
If we carry this thought further, and let our thoughts travel into the realm of speculation, i.e. beyond applied physics, it should also imply that blue light is more strongly bent near a large body, due to the action of gravity, than is red light. I wonder if such a phenomenon has ever been observed? Such an observation would take us, from speculation or myth, into the realm of physics.
What interpretations in astronomy and particle physics may require a second look, if indeed photons have some mass, is another subject for much further speculation. We have known since 1901, that e/m decreases as speed increases. But the issue whether mass increases with speed, or, instead, charge decreases, needs to be looked at again. Photons, including gamma rays and cosmic rays, (which are about as speedy as things can get) are neutral, and perhaps losing charge is what happens to matter as speed increases. That is a tempting thought – at this point only a dream or conjecture.
A question that can be asked, but probably not easily answered, concerns the event of a supernova explosion. What happens in the minutes or seconds just before the explosion? What nuclear reactions may be generated in a star, unique to the immense temperatures and pressures just prior to the eruption? That such reactions are present is suggested by the data on ‘neutrino’ detection on February 23, 1987. This unique, one-time event occurred simultaneously (actually three hours earlier) with the initial visual sighting of the only supernova since the 17th century, that is visible with the naked eye. What rare entities these ‘neutrinos’ are, that apparently travel at the speed of visible light, or perhaps more, and can penetrate deep into chambers, buried far underground, where no light can reach, is a question that boggles the mind. They are not entities we have created in our laboratories, and calling them neutrinos may be begging the question. The material that is ejected in the explosion, atoms and ions of hydrogen and heavier elements, material that generates x-rays, cosmic rays, gamma rays, etc, years, decades, or centuries after the initial explosion, this material is not subjected to the extreme conditions in the star just prior to the explosion. To assume that there is no difference in the character of the radiation generated before and after the explosion may not do justice to such cataclysmic events as supernovae.
But to answer the original question: Theoretical Physics, as currently practiced, is, at this point, largely myth. It is too bad to leave it, or to find it, in such a shambles. But with Einstein’s Second Principle discredited as self-contradictory, with the derivation of the Lorentz Transformation shown to be invalid, with Einstein’s views on simultaneity and synchronization shown to be naïve, ambiguous, and false, and with the constancy of the speed of ‘light’ as disputable, there is little to cling to as factual or comforting in twentieth century theoretical physics.
I am deeply indebted to my friend, Dr. Peter Marquardt, for discussions, alternative points of view, and continuing dialog and cooperation, in teasing out new ways of approaching the ‘ultimate’ questions of natural science and physics.