Was the Universe Created from Leptons?

Graeme Putt

 

INTRODUCTION

Ernest Rutherford set the nuclear ball rolling with his pioneering experiments of alpha-particles scattering off gold atoms in the early part of the 20th century1. He subsequently deduced that atomic matter separated into two ‘fundamental’ classes of particles, electrons that roamed in orbitals occupying the major space of the atom and nucleons (protons and neutrons) locked inside the nucleus, an entity some 100,000 times smaller in size than the atom itself. The major distinguishing factor was their mass, the electron being a featherweight in comparison to the nucleons, similarly massed and about 2000 times as massive as the electron. There are similarities and other differences within this triumvirate: the electron and proton carry electric charges of equal magnitude but opposite polarity, while the neutron has no charge (i.e. is neutral) but is very similar in mass to the proton.

Almost four score years on from the discovery of the neutron, we now know that the only truly fundamental of these particles is the electron. The neutron in its free state decays into a proton, an electron and a neutrino (strictly an electron antineutrino), a chargeless entity of ultra small, if any, mass. We also know there are other exotic particles of mass intermediate between that of the electron and nucleon. They are called pions, kaons, muons, etc., all unstable particles either charged or neutral. Accordingly modern physics has classified its elementary particles into three groups: leptons (from the Greek leptos, meaning ‘small’ or ‘light’), mesons (from meso, meaning ‘middle’) and baryons (from baryon meaning ‘heavy’). The leptons (electrons, muons, tauons and their associated neutrinos) and baryons (protons, neutrons, etc) are fermions, particles with intrinsic spins and angular momentum of ½(h/2π). But the mesons are bosons, particles with either zero intrinsic spin or with angular momentum consisting of integral multiples of h/2π. The mesons are composite structures of fermions insomuch as a free, positively charged pion decays into a positively charged muon and a muon neutrino.

The latter half of the last century focussed on the study of sub-nuclear matter. Today ‘quarks’ are the accepted sub-particles of the nucleons. The subject of nuclear physics subsequently bifurcated into low-energy nuclear physics contenting itself with the collective behaviour of individual nuclei, and high-energy physics (also called particle physics) contenting itself with the inner structure of the nucleon. Inevitably the subjects of particle physics and cosmology have coalesced to work co-operatively towards a better understanding of the nature of the creation process and its evolution.

Today, the most widely accepted theory of creation of the Universe is the Big Bang theory. Leptons (integrally charged electrons and neutrally charged neutrinos) and fractionally charged quarks that accreted into the baryons were produced in matter-antimatter pairs by the phenomenon of associated production. Some intellectual comfort can be extracted out of this cataclysmic event of an unsourced, unimaginable release of energy within some kind of ‘focal point’ of space and time from the prophetic words of Aurelius Augustinas Hipponensis [354 – 430 AD] otherwise known as St Augustine. The great Christian apologist, influenced by Plato with ideas of eternity that are changeless and timeless, prophetically heralded the Big Bang theory of Creation by proclaiming:

non in tempore sed cum tempore finxit Deus mundum

‘God created the Universe with time not in time’. Thus time (and space as well as matter) came into existence with the Big Bang for cosmologists and theologians alike. There was no before, only an after with the Big Bang explosion that created the Universe.

MASS: A PROPERTY OF NATURE OR A USEFUL CONCEPT?

The mass of the particles from which the Universe evolved has always been at the heart of classifying the fundamental particles of nature. Indeed the most elusive, established particle pervading the universe is the neutrino and one of its most intriguing properties is whether it has any mass at all.

Mass is a concept that has served all of science well for centuries, so well in fact that it is tacitly accepted as a fundamental property of nature. Indeed it was essential to the development of Newtonian mechanics that has served (and continues to serve) mankind kindly since the time of the mid-17th century. However, for the past century mass has been linked synonymously with energy through Einstein’s famous equation of mass-energy equivalence, E = mc2. Thus the colossal release of energy in the Big Bang, whose origin Physics has no ready explanation, nevertheless gives rise to the logical formation of matter from the truly fundamental particles from which the Universe has evolved.

Although the modern approach in cosmology and high-energy physics is to theoretically merge the four fundamental physical interactions – the gravitational, electromagnetic, weak and strong (nuclear) interactions – into a single, unified interaction, it is convenient to consider them in this essay in the four separate ways they manifest themselves. The gravitational interaction, enunciated in 1687 as Newton’s Law of Gravity, is the feeblest of the four by many orders of magnitude. But is gravity a phenomenon that is as fundamental as physics proclaims? Nowadays we are reliably informed by high energy physicists that the original (Rutherfordian) short-range nuclear force that binds nucleons together to form stable nuclei is really a kind of van der Waal’s remnant of the strong nuclear colour force that binds quarks together. Taking that analogy a step further, perhaps the gravitational force is nothing more than a remnant of the electromagnetic interaction and not in itself a fundamental interaction.

This brings us to an interesting question regarding mass, the property that drives Newton’s Law of Gravity. Is it a fundamental property of nature like electric charge and intrinsic spin are, or is it a property derived from the existence of the rest of the matter in the Universe? We know from the acceleration of charged particles to relativistic speeds that electric charge (and intrinsic spin) remains immutable under the effect of motion. On the other hand we note that mass in its inertial sense is variable, being velocity dependent. A well-behaved property of nature should be immutable. Perhaps this, plus Einstein’s mass–energy equation is telling us that mass is really an artefact, not a fundamental property of nature. Relativistically we note that displacement (space), a vector quantity, contracts with velocity, but only along the direction of the object’s motion. Thus as matter moving at relativistic speeds to other objects in the Universe contracts in size, the gravito-inertial force the object experiences dilates by the same factor, namely the Lorentz factor! Could it be that mass is a derived quantity based inversely on the spatial distribution of all of the rest of the matter in the universe? If so then do we really need the ubiquitous Higgs boson to salvage present notions of the masses of such things as quarks (entities not directly observable) and the W and Z particles the high-energy physicists demand from future experiments?

Another interesting conceptual aspect of mass occurs with antimatter. Dirac was the first person to predict the existence of anti-matter [as well as account for the electron’s intrinsic spin of ½(h/2π)] with his development of a Relativistic Wave Equation to describe the motion of the electron in 1928. Anti-matter has the complementary properties of ordinary matter being its mirror image – opposite electric charge, opposite weak charge, etc, except it has a positive mass just like ordinary matter! Dirac predicted the existence of a positively charged particle of equivalent mass and the same intrinsic spin of the electron. Such a particle, the positron, was discovered in 1932 in the cosmic rays. As accelerators of increasing energy came on stream, particles like the antiproton and the antineutron appeared on the scene in the mid-1950’s thanks to Einstein’s mass-energy formula and the phenomenon of associated production. This is the process in which matter and antimatter pairs are produced conserving such quantities as electric charge, baryon number, lepton number, linear and angular momentum as well as mass-energy in so doing. If antimatter and matter are obedient to Newton’s Law of Gravitation in a like way, then it suggests mass may be a quantity derived from the other truly fundamental properties of matter.

The purpose of questioning the status of mass is far reaching insomuch as it probes the very essence of the currently accepted theories of the birth of the universe and its basic building blocks. As we shall see shortly, the quarry of the largest accelerator ever commissioned in the world is a theoretical entity that supposedly gives credence to the masses the elementary particles of nature possess.

MATHEMATICS: A BLESSING AND A CURSE.

Dirac’s influence on the development of high-energy physics has been immense.2 He developed a style of doing physics that was guided by mathematics rather than experiment, with the predictions of mathematical theory leading to search by experiment. It is a style at odds with that exploited in earlier times – especially the earlier part of the previous century by Rutherford. Nevertheless the Dirac style has led the development of high-energy physics for decades and a major justification for funding the Large Hadron Collider (LHC) at CERN has been to search for the elusive Higgs boson that is predicted from the mathematics of the Standard Model. The impetus for the currently accepted Standard Model originally came in 1963 from George Zweig and Murray Gell-Mann, working independently of each other. Gell-Mann further predicted the existence of an ‘ultra-strange’ Omega-minus particle (Ω–) based on symmetry arguments and fractionally charged sub-nuclear particles called quarks whose existence he felt was neither demonstrable nor necessary to the existence of the Ω–.3

Because the trend in particle physics has gone in the direction of mathematical prediction and search (and discovery) for so long, physicists outside of its confines might be forgiven for questioning the integrity of one of its sub-disciplines where the tail (theory) seems to wag the dog (experiment). Indeed the sheer ugliness of the Standard Model with its six-pack of differently flavoured and fractionally charged quarks with their internal confinement (and neutral colour mix demand) as well as its accompanying six-pack of leptons to symmetrise matters seems contrived no matter how much adherents of the Standard Model entreat us otherwise.

St Augustine, whose earlier prognostications on the issue of creation resonate with current Big Bang theory, cautioned his followers to be wary of mathematicians:

the good Christian should be wary of mathematicians …… the danger already exists that the mathematicians have made a covenant with the Devil to darken the spirit and confine man in the bonds of Hell.

Mathematical physicists form the present orthodoxy that rules the study of high-energy physics. Their mathematics is so complex that it essentially suffocates all but themselves from any discussion let alone contribution to an understanding of creation. As such it becomes a curse for those who ‘live at the edge of the Universe’ where according to a certain New Zealand poet’s creative mind ‘everyone including myself exists’.4 The writer, himself positioned at the outer edge of physics orthodoxy, believes it is time that orthodoxy was seriously challenged rather than virtuously adored. Encouraged by the ancient wisdom of St Augustine thoughts on mathematicians as well as creation, plus the palpable absence of anything resembling simplicity and beauty in the currently accepted quark theory of hadronic matter has lead him to look elsewhere for enlightenment. He advocates a principle of free fantasy and chooses to exercise it in this essay.5

The free-fantasy principle entitles its user to postulate (via informed guesswork, inspiration, etc) the nature of a set of original conditions then allows them to navigate their way to a set of consequences with a compass governed by the laws of Physics. For this particular offering the presumption is that the Universe was created from the base leptons – electrons and neutrinos, and their antiparticles, positrons and antineutrinos. Its beauty lies in its simplicity of requiring only four elementary particles. This is a stark alternative to the complexity of the 36 quarks plus 12 leptons (six matter and six antimatter leptons) of the ruling Standard Model and its ensuing mathematical predictions. The rest of this essay pursues only two of the manifold consequences possible, but they represent the two most confounding conundrums that confront the subject of creation.6 Ultimately any theory, free-fantasy or orthodox, must confront and satisfy all the experimental facts to merit credibility.

THE TWO MAJOR CONUNDRUMS OF CREATION FOR PHYSICS

The most profound puzzle nature has presented to science for nearly a century is the utter equivalence of the magnitude of the electric charge on the two most basic but different particles in nature, the electron and the proton.7 Both entities are completely stable like no two other known fundamental particles, yet both belong to what are presently perceived as the seemingly ‘orthogonal’ families of baryons and leptons.8 Why is this so?

The second most interestingly item if not completely accepted ‘fact’ within the physics community is that we live in a Universe that is (predominantly) made up of ordinary matter. How can this be given the Universe was initially a fireball whose colossal energy was converted into matter-antimatter pairs in completely equivalent amounts? Well, there are ways around this conundrum for the mathematicians. They introduce the ad hoc notion of ‘symmetry breaking’ and bingo we end up with a universe of ordinary matter. But what help is that to you and others like the author that dwell on the edge of the universe? Can free fantasy do something better? Let us begin!

Consider the equality of the proton and electron charge. Experiments of deep inelastic electron scattering have shown there are three ‘charge centres’ within the proton (and the neutron). The only way you can possibly make a proton from three, electrically charged leptons is from two positrons and one electron! This might seem preposterous to those aware of the phenomenon of electron-positron annihilation. But what if it were true? Bingo – the charge on the proton is self evidentially the same as the charge on the positron and ipso facto the charge on the electron given the phenomenon of associated production.

Whether you can possibly have such a stable cluster of leptons is conveniently shelved to continue discussion of the second conundrum – why do we live in an ordinary matter universe? Well consider a Big Bang explosion where equal numbers of electrons and positrons, and equal numbers (but not necessarily the same number of pairs as for electron-positron creation) of neutrinos and antineutrinos are created at the instant of creation.9 If the proton is a stable unit of two positrons and an electron, the antiproton consists of two electrons and a positron. So for every proton we make we have an electron left over from two electron-positron pairs produced in the Big Bang. And likewise we have a positron left over in the case of the formation of an antiproton. If we tack the electron to the proton we have an ‘ordinary’ hydrogen atom. If we tack the positron to the antiproton we have an antihydrogen atom. Let us take the scenario one step further only instead add a tiny pinch of chaos to the mixture. When we do this we no longer require that we end up with equal numbers of hydrogen atoms and antihydrogen atoms. In fact it can go one way or the other like the throw of a coin. Eventually we might have a million antihydrogen atoms and say a million plus fifty hydrogen atoms from the stochastic nature of the fireball process. This is the same as throwing a perfect coin two million and fifty times and having it come up one million times tails and one million and fifty times heads. Nothing strange about that is there? Now we gather the one million antihydrogen atoms and annihilate them with one million of the ordinary hydrogen atoms. Outside of the self-annihilation debris, ultimately a smorgasboard of gamma radiation and base leptons, we have 50 ordinary hydrogen atoms left. You don’t need esoteric mathematics to end up with any kind of asymmetric Universe you fancy with this kind of scenario. It happens one way (ordinary matter) or the other (antimatter), the former in our special case.

The argument can be easily extended to the formation of neutrons (and antineutrons) for which the obvious lepton triad structure is an electron, a positron and an electron antineutrino. The neutron (with its antineutrino) is made from the initial Big Bang cauldron with an accompanying neutrino that can either escape to the expanding universe or instead become a captive of a different electron positron pair to form an anti-neutron. Add a tiny pinch of chaos and we are left with a small difference of neutrons and antineutrons with one ultimately winning over the other as with the protons.

The consequences of a proton model based on a triad of two positrons and an electron carries good tidings. There is no longer any mystery why the proton and electron charges are equivalent in magnitude. It is self-evident. Furthermore the inherent, random nature of the postulated generation of the nucleons, protons and neutrons, and their antipartners ensures there will be an asymmetry of one form of matter over its conjugate form. The author hopes those at the outer edge of the Universe are pleased by this news. The troublesome tidings like the need to suppress positron-electron annihilation within the proton and the neutron to produce their respective stabilities is left for orthodox physics to wring its hands with. It can do this after the LHC comes on stream and can’t find any meaningful trace of the Higgs boson.

But that’s another story!

ENDNOTES

1. RUTHERFORD: Scientist Supreme, John Campbell, AAS Publications, 1999.
2. ‘A geek for all times’, Richard Lea, Times Literary Supplement, March 13, 2009, page 22.
3. Gell-Mann is often revealed in text-books as having predicted the existence of the Omega minus as some kind of ‘bolt-from-the-blue’. This is not so. Gell-Mann was very much aware of the existence of a similar particle discovered in the cosmic rays by Y. Eisenberg in 1954: Phys Rev 96, 1189 (1954).
4. Lord Rutherford of Nelson, one of the greatest experimental physicists the world has ever known, always maintained that any theory that couldn’t be explained to a janitor wasn’t much of a theory.
5. This is a notion coined by the author who first encountered in a lecture given at UBC in 1970 by Donald Glaser who received the Nobel Prize for his invention of the bubble chamber.
6. The conditions of entry to the 2009 Manhire Competition limit entries to a maximum of 3000 words.
7. The Cosmic Onion, Frank Close, Heinemann Educational Books, 1990, p 108.
8. Proton decay though hypothesised by theorists has never been observed despite serious searches to date. The principal decay mode is hypothesised as:
   p –> πº + e+
   a process otherwise forbidden by the Conservation of Baryon Number principle.
9. The numbers of electron-positron pairs and neutrino-antineutrino pairs are not of necessity equal. Indeed they might be anticipated to be very unequal given the different masses and the additional electromagnetic charge effect within the electron-positron pairing.