Plasma cosmology

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File:Plasma-universe-cosmology.jpg
Plasma Universe and plasma cosmology. Hannes Alfvén urged the application of laboratory and magnetospheric data, and Anthony Peratt of large-scale particle-in-cell simulations, to non-in-situ space regions. Together with direct observation of interstellar and intergalactic plasma phenomenon, this leads them to predict a knowledge expansion about the universe, and a backflow of information about laboratory plasmas. (Click image to enlarge)

Plasma cosmology is a nonstandard cosmological model based on the electromagnetic properties of astrophysical plasmas. In this model, the stars and essentially all of the space between them is filled with plasma, electrically conducting gas in which electrons are stripped away from atoms and can move freely. Plasma cosmology attempts to explain the large scale structure and evolution of the universe, from galaxy formation to the cosmic microwave background, in terms of this phase of matter.

Overview

The basic assumptions of plasma cosmology are,

  1. since the universe is nearly all plasma, electromagnetic forces are equal in importance with gravitation.
  2. since we never see effects without causes, we have no reason to assume an origin in time for the universe—an effect without a cause. Thus this approach, in contrast to the currently dominant Big Bang cosmology, does not assume any beginning for the universe.
  3. unlike the Steady state theory, the universe is not changeless. Rather, since every part of the universe we observe is evolving, it assumes that the universe itself is evolving as well.

Plasma cosmology also differs from big bang cosmology methodologically. The plasma approach emphasizes the links between physical processes observable in laboratories on Earth and those that govern the cosmos. It therefore attempts to explain the universe as much as possible in terms of known physics, rather than allowing, as mainstream cosmology does, the introduction of multiple new entities, such as inflation, dark matter and dark energy, which have not been detected in laboratory experiments. Plasma cosmologists, on the other hand, use the theoretical and experimental results of laboratory plasma physics in cosmological applications.

Plasma cosmology was first developed by Swedish physicist Hannes Alfvén in 1942 (see references), and subsequently together with Oskar Klein, Per Carlqvist and Carl-Gunne Fälthammar. Alfvén was the founder of modern plasma physics, for which he received the Nobel prize. While plasma cosmology has never had the support of a large number of astronomers and physicists, a small group of plasma physicists such as Anthony Peratt and Eric Lerner have continued to develop the approach. As a result the approach now proposes theories for the origin of large scale structures, such as galaxies and cluster and superclusters of galaxies, quasars, the light elements, and the cosmic microwave background. Proponents argue that these theories could explain observations more economically, without introducing the new physics required by the big bang theory. Critics of the theory point out that detailed observational testing of the more mature big bang cosmology has not been rivalled by plasma cosmology.

Alfvén's research

File:Hannes-alfven-stamp.jpg
Hannes Alfvén (1908-1995), made significant advances in the study of plasmas and their application to physics and astronomy

Alfvén's model of plasma cosmology can be divided into two distinct areas.

  1. Cosmic Plasma, his empirical description of the Universe based on the results from laboratory experiments on plasmas
  2. ambiplasma theory, based on a hypothetical matter/antimatter plasma.

Cosmic Plasma

Building on the work of Kristian Birkeland, Alfvén's research on plasma led him to develop the field of magnetohydrodynamics (MHD), a field of work that mathematically models plasma as fluid, and for which he won the Nobel Prize for Physics in 1970. MHD is readily accepted and used by astrophysicists and astronomers to describe many celestial phenomena. However, Alfven pointed out that MHD is an approximation which is accurate only in dense plasmas, like that of stars, where particles collide frequently. It is not valid in the much more dilute plasmas of interstellar and intergalactic space, where electrons and ions circle around the magnetic field lines. Alfven devoted a large section of his Nobel address to attacking this “pseudo plasma” error.

Alfvén felt that many other characteristics of plasmas played a more significant role in cosmic plasmas. These include:

Alfven and his colleagues began to develop plasma cosmology in the 1960’s and 70’s as an extrapolation of their earlier highly successful theories of solar and solar-system phenomena. They pointed out those extremely similar phenomena existed in plasmas at all scales because of inherent scaling laws, ultimately derived from Maxwell's laws. One scale invariant in plasmas is velocity, so that plasmas at scales from the laboratory up to supercluster of galaxies exhibit similar phenomena in a range of velocities from tens to a thousand kilometers per second. In turn this invariance means that the duration of plasma phenomena scales as their size, so that galaxies a hundred thousand light years across with characteristic evolution times of billions of years scale to transient laboratory-scale phenomena lasting a microsecond.

While gravity becomes important at large scales, electromagnetic forces are claimed by plasma cosmology advocates to be rarely negligible and indeed are said to often dominate cosmic processes. Magnetic forces are particularly important since even in neutral plasma (such as almost all astrophysical plasmas) magnetic forces have infinite range, like gravity. For example, in the Local Supercluster of galaxies, the magnetic field is at least 0.3 microgauss over a volume 10 Mpc in radius, so here the magnetic field energy density exceeds the gravitational energy density by at least an order of magnitude.

Alfvén and his collaborators pointed to two plasma phenomena that are crucial in understanding the cosmos. The first is the formation of force-free filaments. When currents move through any plasma, they create magnetic fields which in turn divert currents in such a way that parallel currents attract each other (the pinch effect). Plasma thus naturally become inhomogeneous, with currents and plasmas organizing themselves into force-free filaments, in which the currents move in the same direction as the magnetic field.

Such filaments act to pinch matter together which in turn leads (for large enough filaments) to gravitational instabilities that cause clumps to form along the filaments like beads on a string. These gravitationally-bound clumps, spinning in the magnetic field of the filament, generate electric forces that create a new set of currents moving towards the center of the clump, as in a disk generator. This in turn creates a new set of spiral filaments that set the stage of the coalescence of smaller objects. A hierarchy of superclusters, clusters, galaxies stars and planets is thus formed.

These filaments, as Alfvén and colleagues showed, are critical to the process of gravitational collapse, because they act to transfer angular momentum from the contracting clump. Without such magnetic breaking, the formation of galaxies and stars would be impossible as centrifugal force would prevent contraction. Subsequent to Alfven’s work, the highly magnetized filaments were discovered at several scales in the cosmos, from parsec-scales at the center of the galaxy to supercluster filaments that stretch across hundreds of megaparsecs.

The second phenomenon was the exploding double layer, where charge separation builds up in a current-carrying plasma, leading to the disruption of the current, the generation of high electric fields and the acceleration of energetic particles. This phenomenon, observed in the laboratory, Alfven applied to understand cosmic rays among other phenomena.

Ambiplasma

As physical theories and experimental evidence from particle physics show that matter and antimatter always come into existence in equal quantities, Alfvén and Klein in the early 1960s developed a theory of cosmological evolution based on the development of an "ambiplasma" consisting of equal quantities of matter and antimatter. Alfvén theorized that if an ambiplasma was affected by both gravitational and magnetic fields, as could be expected in large-scale regions of space, matter and antimatter would naturally separate from each other. When small matter clouds collided with small antimatter clouds, the annihilation reactions on their border would cause them to repel each other, but matter clouds colliding with matter clouds would merge, leading to increasingly large regions of the universe consisting of almost executively matter or antimatter. Eventually the regions would become so vast that the gamma rays produce by annihilation reactions at their borders would be almost unobservable.

This explanation of the observed dominance of matter in our local part of the universe contrasted sharply with that proposed by big bang cosmology, which requires an asymmetric production of matter and antimatter at high energy. (If matter and antimatter had been produced in equal quantities in the extremely dense big bang, annihilation would have reduced the universal density to only a few trillionths of that observed.) Such asymmetric matter-antimatter production has never been observed in nature.

Alfvén and Klein then went on to use their ambiplasma theory to explain the Hubble relation between redshift and distance. They hypothesized that a very large region of the universe consisting of both matter and antimatter sub-regions, gravitationally collapsed until the matter and antimatter regions were forced together, liberating huge amounts of energy and leading to an expansion of our part of the universe. At no point in this model, however, does the density of our part of the universe become very high.

This explanation the Hubble relationship is not upheld by later analysis. Carlqvist determined that there was no way that such a mechanism could lead to the very high redshifts, comparable or greater than unity, that were observed. While Alfven’s separation process was soundly based, it seemed almost impossible for the process to reverse and lead to a re-mixing of matter and antimatter.

Current features and problems for plasma cosmology

In the past twenty-five years, plasma cosmology has expanded to develop models of the formation of large scale structure, quasars, the origin of the light elements, the cosmic microwave background and the redshift-distance relationship

Formation of structure

In the early 1980’s Peratt, a former student of Alfvén’s, used supercomputer facilities at Maxwell Laboratories and later at Los Alamos National Laboratory to simulate Alfvén and Fälthammar’s concept of galaxies being formed by clouds of plasma spinning in a magnetic filament. The simulation began with two spherical clouds of plasma trapped in parrallel magnetic filaments, each carrying a current of around 1018 amps. In a video created from the simulation, the clouds begin to rotate around each other, spin on their own axes and distort their shape until a perfectly formed spiral galaxy emerges [Ref] [Ref]. Peratt showed that the stages of formation closely corresponded to observed galaxy shapes. In addition, the rotation curves of the simulated galaxy showed the same plateau in velocity as do real galaxies.

While the simulation did not contain gravitational forces, so could not be wholly realistic, it demonstrated that electromagnetic processes could lead to the forms observed at a galactic scale. In addition, Peratt’s work cast doubt on widely-cited calculations that used the flat rotation curves of plasmas in the outer reaches of galaxies as evidence for dark matter. Such plasma could instead be contained by magnetic fields. The evidence for this explanation was increased when, in 2005, observers found stars in the outer reaches of the Andromeda galaxy that were moving far slower than the plasma at the same radius. This indicated that the gravitational forces, which the stars responded to, were less strong than those indicated on the basis of the plasma motion and that less or perhaps no dark matter was required.

During the same period, Lerner developed a plasma model of quasars based on the functioning of the dense plasma focus fusion device. In this device, converging filaments of current form a tight, magnetically confined ball of plasma on the axis of cylindrical electrodes. As the magnetic field of the ball, or plasmoid, decays, it generates tremendous electric fields that accelerate a beam of ions in one direction and a beam of electrons in the other. In Lerner’s model, the electric currents generated by a galaxy spinning in a intergalactic magnetic field converge on the center, producing a giant plasmoid, or quasar. This metastable entity, confined by the magnetic field of the current flowing through it, generates both the beams and intense radiation observed with quasars and active galactic nuclei. Lerner compared in detail the predictions of this model with quasar observations. In addition the quantitative model of the plasma focus developed in this work was used in efforts aimed at developing the device as a fusion generator.

In the mid-80’s Lerner used plasma filamentation theory to develop a general explanation of the large scale structure of the universe. While big bang cosmology has difficulty accommodating the formation of very large structures, such as voids 100 Mpc or more across, in the limited amount of time available since the hypothesized origin of the universe, plasma cosmology can easily accommodate large scale structures, and in fact firmly predicts a fractal distribution of matter with density being inversely proportional to the distance of separation of objects.

Plasma filamentation theory allows the prediction of the mass of condensed objects formed as a function of density. Magnetically confined filaments initially compress plasma, which is then condensed gravitationally. For this to happen, the plasma must be collisional. Otherwise, particle will just continue in orbits like the planets of the solar system. Given the characteristic ion velocity in the filament, calculated from instability theory, the collisional condition generates the relation that objects of mass M =1.8n-2 form from plasma of initial density n, where M is in solar masses and n in ions/cm3. This fractal scaling relationship (fractal dimension=2) has been borne out by many studies on all observable scales of the universe. In addition, the numerical constant in the relation between mass and density, or equivalently, mass and separation of objects (M = 9.7 x1010 R2, where R is in Mpc and M is in solar masses) has been borne out by observation. In the plasma model, where superclusters, clusters and galaxies are formed from magnetically confined plasma vortex filaments, a break in the scaling relationship is only anticipated at scales greater than approximately 3Gpc. Naturally, since the plasma approach hypothesizes no origin in time for the universe, the large amounts of time needed to create large-scale structures present no problems for the theory.

Light elements abundance

The structure formation theory allowed Lerner to calculate the size of stars formed in the formation of a galaxy and thus the amounts of helium and other light elements that will be generated ruing galaxy formation This lead to the predictions that large numbers of intermediate mass stars (from 4-12 solar masses) would be generated during the formations of galaxies . These stars produce and emit to the environment large amounts of 4He, but very little C, N and O.

The plasma calculations, which contained no free variables, lead to a broader range of predicted abundances than does Big Bang nucleosynthesis, because the plasma theory hypothesizes a process occurring in individual galaxies, so some variation is to be expected. The range of values predicted for 4He is from 21.5 to 24.8%. However, the theory is still tested by the observations, since the minimum predicted value remains a firm lower limit (additional 4He is of course produced in more mature galaxies). This minimum value is completely consistent with the minimum observed values of 4He abundance, such as H II region, UM461, with an abundance of 21.9±0.8% .

In addition cosmic rays from these stars can produce by collisions with ambient H and He the observed amounts of D and 7Li. Deuterium production by the p+p->d+pion reaction has been predicted by plasma theory to yield abundances of the order of 2.2x10-5 . This prediction was made in 1989, at a time when no observations of D in low-metalicity systems were available and the consensus values for primordial D from Big Bang theory were 3-4 times higher. Yet this predicted value lies within the range of observed "primordial" D values, although somewhat below the average D values.

In its present form, the plasma-stellar theory of light elements does not give a prediction for the absolute abundance of 7Li. However, the theory unambiguously predicted that abundance depended on CNO abundance and subsequent observations have clearly verified that prediction. Observations of the abundances of 6Li, which is also generated by cosmic rays, but is destroyed much more readily in stars, is also completely consistent with a cosmic-ray origin for 7Li.

Microwave background

Even though mainstream interest in plasma cosmology rapidly waned as precise measurements of the cosmic microwave background (CMB), such as those by COBE, both Anthony Peratt and Eric J. Lerner have proposed that plasma cosmology could explain the CMB. In particular, Lerner has shown that plasma cosmology can generate a background by synchrotron radiation. This model fails to predict the CMB anisotropy peaks in the power spectrum or the precise black-body nature of the spectrum. In particular, it fails to predict the 1 degree mode on the sky or the strength of this feature.

Redshifts

Cosmological redshifts are a ubiqitous phenomenon seen that is summarized by the Hubble Law where more distant galaxies have greater redshifts. Advocates of plasma cosmology dispute the claim that this observation indicates an expanding universe and even dispute the more prosaic explanation (used by, for example, the Steady State theory) that they are an indication of recessional velocities. Instead, alternative mechanisms for redshifts are desired.

Although there are many local photon frequency shifting mechanisms observed in laboratory experimentation with plasmas, one problem in using a majority of them to explain cosmological redshifts is that it is difficult to account for a change in the energy of a photon going through plasma without photon scattering (changing the photon's direction of propagation.) In some non-linear optical phenomena, it is argued there may be forms of scattering in which the direction of propagation of the photons is not changed. Specifically, one favorite phenomenon for plasma cosmology advocates is Forward Brillouin Scattering, found locally in laser fusion devices, as an example. This form of forward scattering causes a frequency shift over a range of photon energies and a broadening of spectral lines without changing the direction of propagation of the incident light. However, it does not explain the redshifting of high energy or low energy photons as the conventional explanations do.

Dark matter, dark energy

Advocates of plasma cosmology claim that the observations that are typically seen as evidence for dark matter and dark energy in mainstream cosmology can be explained by plasma processes affecting the dynamics and the redshifts that are associated with these features. It is not clear, however, that evidence from gravitational lensing or from the matter power spectrum or the cosmic microwave background for these features can be explained by plasma processes alone.

Future

Plasma cosmology is not an established scientific theory, and even most advocates agree the explanations provided are much less complete than those of conventional cosmology. Within plasma cosmology, there have been no published papers which make predictions on the primordial helium abundance or which calculate correlation functions.

Figures in plasma cosmology

The following physicists and astronomers helped, either directly or indirectly, to develop this field:

  • Hannes Alfvén - Along with Birkeland, fathered Plasma Cosmology and was a pioneer in laboratory based plasma physics. Received the only Nobel Prize ever awarded to a plasma physicist.
  • Halton Arp - Astronomer famous for his work on anomalous redshifts, "Quasars, Redshifts and Controversies".
  • Kristian Birkeland - First suggested that polar electric currents [or auroral electrojets] are connected to a system of filaments (now called "Birkeland Currents") that flowed along geomagnetic field lines into and away from the polar region. Suggested that space is not a vacuum but is instead filled with plasma. Pioneered the technique of "laboratory astrophysics", which became directly responsible for our present understanding of the aurora.
  • Eric Lerner - Claims that the intergalactic medium is a strong absorber of the cosmic microwave background radiation with the absorption occurring in narrow filaments. Postulates that quasars are not related to black holes but are rather produced by a magnetic self-compression process similar to that occurring in the plasma focus.
  • Anthony Peratt - Developed computer simulations of galaxy formation using Birkeland currents along with gravity. Along with Alfven, organized international conferences on Plasma Cosmology.
  • Nikola Tesla - Developed the rotating magnetic field model.
  • Gerrit L. Verschuur - Radio astronomer, writer of "Interstellar matters : essays on curiosity and astronomical discovery" and "Cosmic catastrophes".

See also

Links and resources

Publications

  • IEEE Xplore, IEEE Transactions on Plasma Science, 18 issue 1 (1990), Special Issue on Plasma Cosmology.
  • G. Arcidiacono, "Plasma physics and big-bang cosmology", Hadronic Journal 18, 306-318 (1995).
  • J. E. Brandenburg, "A model cosmology based on gravity-electromagnetism unification", Astrophysics and Space Science 227, 133-144 (1995).
  • J. Kanipe, "The pillars of cosmology: a short history and assessment". Astrophysics and Space Science 227, 109-118 (1995).
  • O. Klein, "Arguments concerning relativity and cosmology," Science 171 (1971), 339.
  • W. C. Kolb, "How can spirals persist?," Astrophysics and Space Science 227, 175-186 (1995).
  • E. J. Lerner, "Intergalactic radio absorption and the Cobe data", Astrophys. Space Sci. 227, 61-81 (1995)
  • E. J. Lerner, "On the problem of Big-bang nucleosynthesis", Astrophys. Space Sci. 227, 145-149 (1995).
  • B. E. Meierovich, "Limiting current in general relativity" Gravitation and Cosmology 3, 29-37 (1997).
  • A. L. Peratt, "Plasma and the universe: Large-scale dynamics, filamentation, and radiation", Astrophys. Space Sci. 227, 97-107 (1995).
  • A. L. Peratt, "Plasma cosmology", IEEE T. Plasma Sci. 18, 1-4 (1990).
  • C. M. Snell and A. L. Peratt, "Rotation velocity and neutral hydrogen distribution dependency on magnetic-field strength in spiral galaxies", Astrophys. Space Sci. 227, 167-173 (1995).

Related Books

  • H. Alfvén, Worlds-antiworlds: antimatter in cosmology, (Freeman, 1966).
  • H. Alfvén, Cosmic Plasma (Reidel, 1981) ISBN 9027711518
  • E. J. Lerner, The Big Bang Never Happened, (Vintage, 1992) ISBN 067974049X
  • A. L. Peratt, Physics of the Plasma Universe, (Springer, 1992) ISBN 0387975756

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