Plasma cosmology

Cosmic Triple Jump. Hannes Alfvén suggested that by scaling laboratory plasma experiment results by a factor of 10⁹ makes them applicable to magnetospheric conditions. Another scaling jump of 10⁹ makes the results applicable to galactic conditions, and a third jump of 10⁹ takes us out to the Hubble distance.

Plasma cosmology is a non-standard cosmology which emphasizes the electromagnetic properties of astrophysical plasmas. Plasma cosmology includes qualitative explanations for the evolution of the universe — from the cosmic microwave background, to galaxy formation, to large scale structure. Fundamental to its explanations are interpretations of many astrophysical phenomena by scaling results from laboratory experiments. While in the late 1980s to early 1990s there was limited discussion over the merits of plasma cosmology, today advocates for these ideas are mostly ignored by the professional cosmology community.

History

Kristian Birkeland. The year 1996 marked the Centennial Celebration of the founding of Plasma Astrophysics and Cosmology, which may be traced to the research of Kristian Birkeland published in 1896. Birkeland formulated a theory about a plasma-filled universe populated with systems of nebula (galaxies)

Writing in 2003 in the 6th Special Issue of the IEEE Transactions on Plasma Science, guest editor Anthony Peratt wrote that there have been many who have helped pioneer plasma cosmology, including some cited in the first special issue in 1986, namely Kristian Birkeland, Irving Langmuir, P. A. M. Dirac, Karl G. Jansky, Grote Reber, Edward. V. Appleton, and Hannes Alfvén.

Writer Jeff Kanipe wrote in Astrophysics and Space Science, that:

"Plasma cosmology sprang from the pioneering work of Hannes Alfven. Stemming from his studies in the 1950s of synchrotron radiation—emission caused by electrons spiraling at nearly the speed of light in a magnetic field (Alfven and Herlofson, 1950b), Alfven proposed that sheets of electric currents must crisscross the universe (Alfven, 1950a; Alfven and Carl-Gunne_Fälthammar, 1962,). Interaction with these electromagnetic fields would enable plasmas to exhibit complex structure and motion. Thus, at the grandest scales, the universe would have a cellular and filamentary structure."

Oskar Klein in a paper published in 1950 first proposed that astrophysical plasmas may play an important role in galaxy formation. Some 12 years later, Hannes Alfvén, a Nobel laureate in physics, would hypothesize that the baryon asymmetry observed in the universe was due to an initial condition ambiplasma mixture of matter and antimatter. The hypothesized substance would form pockets of matter and pockets of antimatter that would expand outwards as annihilation between matter and antimatter occurred at the boundaries. It was proposed by Alfvén, therefore, that we happened to live in one of the pockets that contained mostly baryons rather than antibaryons. The processes governing the evolution and characteristics of the universe at its largest scale would be governed mostly by this feature. The ambiplasma hypothesis was developed independently of the rival Big Bang and steady state models which were the two most popular competing cosmologies. Together with scientists Per Carlqvist and Carl-Gunne Fälthammar, the Swedish research team developed what would eventually be termed the Alfvén-Klein model — a progenitor of today's nonstandard proposal of "plasma cosmology".

Overview

Plasma cosmology posits that the most important feature of the universe is that the matter it contains is composed almost entirely of astrophysical plasma. The state of matter known as plasma is an electrically-conductive collection of charged particles, possibly together with neutral particles or dust, that exhibits collective behavior and that responds as a whole to electromagnetic forces. The charged particles are usually ions and electrons resulting from heating a gas. Stars and the interstellar medium are composed of plasma of different densities. Plasma physics is uncontroversially accepted to play an important role in many astrophysical phenomena.

The basic assumptions of plasma cosmology which differ from standard cosmology are:

1. Since the universe is nearly all plasma, electromagnetic forces are equal in importance with gravitation on all scales..
2. An origin in time for the universe is rejected, due to causality arguments and rejection of ex nihilo models as a stealth form of creationism.
3. Since every part of the universe we observe is evolving, it assumes that the universe itself is evolving as well, though a scalar expansion as predicted from the FRW metric is not accepted as part of this evolution (see static universe).

Plasma cosmology advocates emphasize the links between physical processes observable in laboratories on Earth and those that govern the cosmos; as many cosmological processes as possible are explained by the behavior of a plasma in the laboratory. Proponents contrast this with the big bang theory which has over the course of its existence required the introduction of such features as inflation, dark matter and dark energy that have not been detectable yet in laboratory experiments.

While plasma cosmology has never had the support of most astronomers or physicists, researchers have continued to promote and develop the approach, and publish in special issues of the IEEE Transactions on Plasma Science that are co-edited by plasma cosmology proponent Anthony Peratt,; the next Special Issue, co-edited with NASA's Dr Timothy E. Eastman, is due in Nov 2007. Papers regarding plasma cosmology were published in other mainstream journals through the 1990s.

Alfvén's model

File:Hannes-alfven.jpg

Hannes Alfvén (1908-1995) made significant advances in the study of plasmas and their application to physics and astronomy

Alfvén's hypotheses regarding cosmology can be divided into three distinct areas.

1. The cosmic plasma, an empirical description of the Universe based on the results from laboratory experiments on plasmas
2. Birkeland currents (force free filaments), a proposed mechanism for the formation of large scale structure in the universe.
3. ambiplasma theory, based on a hypothetical matter/antimatter plasma.

Cosmic plasma

Following the work of Kristian Birkeland, Alfvén's research on plasma led him to develop the field of magnetohydrodynamics, a theory that mathematically models plasma as magnetic fluid, and for which he won the Nobel Prize for Physics in 1970. However, Alfvén pointed out that magnetohydrodynamics 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 the interstellar medium and intergalactic medium, where electrons and ions circle around magnetic field lines. Alfvén devoted a large portion 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:

• Scalability of plasma,
• Birkeland currents, electric currents that form electric circuits in space,
• Plasma double layers,
• The cellular structure of plasma,

Alfvén and his colleagues began to develop extrapolations to larger scales of their 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. They extrapolated, for example, that the duration of plasma phenomena scales as size, so that galaxies a hundred thousand light years across with characteristic evolution times of billions of years were associated by them with transient laboratory-scale phenomena lasting a microsecond.

While gravity is important at large scales, magnetic forces may also be important even in neutral plasma (like almost all astrophysical plasmas) since magnetic forces, like gravity, cannot be shielded. For example, in the Local Supercluster of galaxies, the magnetic field is 0.3 microgauss over a volume 10 Mpc in radius centered on the Milky Way.

Alfvén and his collaborators pointed to two plasma phenomena that have figured prominently in subsequent developments of plasma cosmology:

1. The formation of force-free filaments. (See section below)
2. 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, which was first observed in the laboratory, was suggested by Alfvén as a possible mechanism for the generation of cosmic rays.

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 becomes 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 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 structure is thus formed.

The so-called magnetic braking in these filaments, as Alfvén and colleagues showed, may be important for the process of gravitational collapse, because they serve as a mechanism to transfer angular momentum from the contracting clump. Without a process to transfer angular momentum, the formation of galaxies and stars would be impossible as centrifugal forces would prevent contraction. Plasma cosmology controversially asserts that such plasma processes can ultimately account for the large-scale structure of the universe and its filamentary organization of superclusters, clusters, galaxies, stars and planets. Subsequent to Alfvén’s work, 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.

Ambiplasma

Main article: Ambiplasma

As theoretical considerations and experimental evidence from particle physics showed 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 exclusively matter or antimatter. Eventually the regions would become so vast that the gamma rays produced by annihilation reactions at their borders would be almost unobservable.

This explanation of the dominance of matter in the local universe contrasts 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 parts alternately containing matter and antimatter, gravitationally collapsed until the matter and antimatter regions were forced together, liberating huge amounts of energy and leading to an explosion. At no point in this model, however, does the density of our part of the universe become very high. This explanation was appealing, because if we were at the center of the explosion we would observe the Doppler shifts from receding particles as redshifts, and the most distant particles would be the fastest moving, and hence have the largest redshift.

This explanation of the Hubble relationship did not withstand analysis, however. Carlqvist determined that there was no way that such a mechanism could lead to the very high redshifts, comparable to or greater than unity, that were observed. Moreover, it was difficult to see how the high degree of isotropy of the visible universe could be reproduced in this model. While Alfvén’s separation process was sound, it seems almost impossible for the process to reverse and lead to a re-mixing of matter and antimatter.

Features and problems

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

File:Peratt-galaxy-formation-simulation.gif

Peratt's galaxy formation simulation: Single frame stills of plasma in the simulation of two adjacent Birkeland filaments, featuring flat rotation curves without the introduction of dark matter. The diagram pertains to the cross-sectional views of two plasma filaments of width 35 kpc and separation about 80 kpc. The axial extent of the simulation is only 10 kpc, so the formation of a 3-d disk is not demonstrated by this calculation. It is argued that the axial extent is determined either by the length of the "micro-pinch" within the filament (in comparison to the analogy of laboratory filaments) or to the width of the double layer formed in the Birkeland current; these are typically comparable to the filamental width. (Peratt, 1986) Animated version

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 primordial clouds of plasma spinning in a magnetic filament. The simulation began with two spherical clouds of plasma trapped in parallel magnetic filaments, each carrying a current of around 10¹⁸ amperes. 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 spiral shape emerges. Peratt compared the various stages in his simulation with observed galaxy shapes, concluding that they appeared highly similar. Additionally, Perrat's forms had flat rotation curves without invoking dark matter. While Peratt believes the forms are applicable to galaxy formation, Peratt's model does not describe the majority of the visible mass of developed galaxies, which is in the form of stars. In contrast to Peratt, Lerner accepts the existence of dark matter, but believes it to be in the form of difficult to observe baryonic dark matter.

Peratt's simulation differs substantially from standard galaxy formation models which rely on hierarchical structure formation of dark matter into the superclusters, clusters, and galaxies seen in the universe today. The size and nature of such forms are based on an initial condition from the primordial anisotropies seen in the power spectrum of the cosmic microwave background. Most astrophysicists accept dark matter as a real phenomenon and a vital ingredient in structure formation, which cannot be explained by appeal to electromagnetic processes. The mass estimates of galaxy clusters using gravitational lensing, which is a measurement independent of the rotation curves, also indicate that there is a large quantity of dark matter present independent of the measurements of galaxy rotation curves.

In the mid-80s Lerner used plasma filamentation to develop a general explanation of the large scale structure of the universe. Lerner concluded that plasma cosmology could produce large scale structures while he argued that big bang cosmology did not accommodate the formation of very large structures (such as voids 100 Mpc or more across) in the limited amount of time available since the Big Bang. Recent simulations, however, show rough agreement between observations of galaxy surveys and N-body cosmological simulations of the Lambda-CDM model. Many astronomers believe that achieving detailed agreement between observations and simulations in the big bang model will require improved simulations of structure formation (with faster computers and higher resolution) and a better theoretical understanding of how to identify voids and infer the distribution of invisible dark matter from the distribution of luminous galaxies.

Lerner's theory allows the mass of condensed objects formed to be predicted as a function of density. Magnetically confined filaments initially compress plasma, which is then condensed gravitationally into a fractal distribution of matter. For this to happen, the plasma must be collisional — a particle must collide with at least one other in crossing the object. Otherwise, particles will just continue in orbits like the planets of the solar system. This condition leads to the prediction of a fractal scaling relation in which the structures are formed with density inversely proportional to their size. This fractal scaling relationship (with fractal dimension equal to two) is a key prediction of plasma cosmology. Ten years ago, measurements from limited numbers of galaxy counts seemed to indicate a fractal scaling was possible.

In the big bang model, by contrast, the cosmological principle suggests the universe is homogeneous on large scales, and structures form hierarchically: the smallest objects forming first followed by larger objects. Studies have long suggested that fractal scaling is true only on small scales, and that observations indicate that the universe is homogeneous on large scales without evidence of the very large scale structure required by the fractal universe. The largest galaxy number count to date, the Sloan Digital Sky Survey, confirms this picture.

Quasars

Lerner developed a plasma model of quasars based on 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 an 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. This contradicts the standard model of quasars as distant active galactic nuclei (that is, supermassive black holes which are illuminated by radiation from the luminous matter they are accreting).

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 during galaxy formation. This led to the predictions that large numbers of intermediate mass stars (from 4-12 solar masses) would be generated during the formations of galaxies. Standard stellar evolution theory indicates that these stars produce and emit to the environment large amounts of helium-4, but very little carbon, nitrogen and oxygen. The plasma calculations led to a broader range of predicted abundances than Big Bang nucleosynthesis, because a process occurring in individual galaxies would be subject to individual variation. The minimum predicted value is consistent with the minimum observed values of ⁴He abundance.

In order to account for the observed amounts of deuterium and the two isotopes of lithium, Eric Lerner has posited that cosmic ray protons with an energy around 1 GeV from the early stars could, by collisions with ambient hydrogen and other elements, produce the light elements unaccounted for in stellar nucleosynthesis. This mechanism is similar to one suggested by Audouze and Silk. Audouze et al. identify "two pitfalls in such schemes for ²H synthesis": excessive x-ray production and excessive lithium production. Epstein et al. had already pointed out in 1976 that proton fluxes with energies greater than 500 MeV, if they are intense enough to produce the observed levels of deuterium, would also produce about 1000 times more gamma rays than are observed. Lerner (1989) includes a paragraph on "Gamma Rays from D Production" in which he claims that the expected gamma ray level is consistent with the observations. He cites neither Audouze nor Epstein in this context, and does not make it clear why his result contradicts theirs.

Microwave background

It has long been noted that, if the helium-4 observed today had been produced by fusion of hydrogen, the energy released would be approximately equal to the energy in the cosmic microwave background (CMB). Plasma cosmology advocates argue that "primordial" helium was not produced in Big Bang nucleosynthesis but in stellar nucleosynthesis in the early stages of the formation of galaxies, and that the energy released was subsequently thermalized and is now observable as the CMB. In order for such a model to yield the near-perfect observed blackbody spectrum, Peter and Peratt hypothesized that the stellar radiation is thermalized and isotropized by a thicket of dense, magnetically confined plasma filaments that pervade the intergalactic medium. This model was later extended by Lerner. In particular, Lerner was able to adjust the few free parameters of his model to match the spectrum measured by COBE within experimental errors and estimated that the isotropies expected in his model do not exceed those observed by COBE. There have been no improvements in the measurement of the blackbody spectrum since COBE, but the sensitivity and resolution of the measurement of anisotropies was greatly advanced by WMAP. These measurements showed "acoustic peaks" which could be fit with high accuracy by the predictions of the Big Bang model. Although neither Lerner nor Peratt has published on this topic since the WMAP data became available, there is no indication in their previous papers how the detailed angular power spectrum of anisotropies could follow from the plasma model.

Since the hypothesized filaments would scatter radiation longer than 100 micrometres, the theory predicted that radiation longer than this from distant sources will be scattered, and thus will decrease more rapidly with distance than does radiation shorter than 100 micrometres. Lerner concluded that such absorption or scattering was demonstrated by comparing radio and far-infrared radiation from galaxies at various distances: the more distant, the greater the absorption effect. Lerner also suggests this effect explains the well-known fact that the number of radio sources decreases with increasing redshift more rapidly than the number of optical sources.

Redshifts

Cosmological redshifts are a ubiquitous phenomenon that is summarized by Hubble's law in which more distant galaxies have greater redshifts. One of the key assumptions of plasma cosmology is that this observation does not indicate an expanding universe.

In a 2005 paper, Lerner used recent data on high-redshift galaxies from the Hubble Ultra Deep Field in an attempt to test the predictions of the expanding-universe explanation of the Hubble relation. The big bang model predicts the apparent surface brightness (brightness per unit apparent area) of galaxies of the same absolute magnitude should decrease at increasing distance according to a specific power law calculated by Tolman. Lerner concluded that observations show that the surface brightness of galaxies up to a redshift of six are constants predicted by a non-expanding universe and in sharp contradiction to the big bang. Lerner states that attempts to explain this discrepancy by changes in galaxy morphology lead to predictions of galaxies that are impossibly bright and dense. Standard models of galaxies suggest, however, galaxy morphology is very different at high redshifts.

Lerner's result disagrees with the results of Lubin and Sandage, astronomers at Caltech and the Carnegie observatories, who performed similar tests on a high quality selection of well-calibrated lower-redshift (up to z of 0.92) galaxies and concluded they are consistent with an expanding universe. Another measure of the expansion of the universe, the time dilation of supernova light curves, is also cited as evidence that the universe is expanding. However, Lerner argues in the same paper that this is not the case.

While plasma cosmology supporters have supported alternative explanations of the Hubble relation including the Wolf effect, CREIL, and tired light mechanisms, most cosmologists consider the expanding universe to be supported by the overwhelming preponderance of observational evidence in cosmology.

General relativity and plasma cosmology

It is sometimes argued that the finite age of the universe is a generic prediction of general relativity for realistic cosmologies. However, proofs of a universal singularity in the past all rely on additional hypotheses, which may or may not be true. For example, Stephen Hawking and George Ellis argued that generating the thermal, isotropic cosmic microwave background necessarily implies a gravitational singularity in our universe if the cosmological constant is zero. Their calculation of the density of matter and thus their conclusion rested on the assumption that Thomson scattering is the most efficient process for thermalization. But in highly magnetized plasmas other processes such as inverse synchrotron absorption can be far more efficient, as Lerner points out in his theory of the microwave background. With such efficient absorption and re-emission, the amount of plasma needed to thermalize the cosmic microwave background can be orders of magnitude less than that needed to produce a singularity. The implications of general relativity for plasma cosmology have not been studied in detail.

Future

Plasma cosmology is not a widely-accepted scientific theory, and even its advocates agree the explanations provided are less detailed than those of conventional cosmology. Its development has been hampered, as have that of other alternatives to big bang cosmology, by the exclusive allocation of government funding to research in conventional cosmology. Most conventional cosmologists argue that this bias is due to the large amount of detailed observational evidence that validates the simple, six parameter Lambda-CDM model of the big bang.

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.
• 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 Alfvén, organized international conferences on Plasma Cosmology.

See also

• Cosmology: Non-standard cosmology, Intrinsic redshifts, Tired light, Quasars, Redshifts and Controversies, Static universe
• Astrophysics: Theoretical astrophysics, Plasma physics, Astrophysical plasma, Magnetohydrodynamics,
• The ambiplasma model, or the Alfvén-Klein model, is the original model of plasma cosmology.
• The Plasma Universe, Hannes Alfvén's model based in plasma
• Electric Universe, a concept that includes elements of plasma cosmology but is much farther outside the mainstream.

Links and references

• Alfvén, H. "Cosmogony as an extrapolation of magnetospheric research" (1984)
• Alfvén, H. "On hierarchical cosmology" (1983)
• Wright, E. L. "Errors in "The Big Bang Never Happened"".
• Lerner, E. J. "Dr. Wright is Wrong". Lerner's reply to the above.
• Peratt, Anthony, "Plasma Universe". (Related Papers)
• Wurden, Glen, "The Plasma Universe". Los Alamos National Laboratory. University of California (U.S. Department of Energy). (General Plasma Research)
• Marmet, Paul, "Big Bang Cosmology Meets an Astronomical Death". 21st Century, Science and Technology, Washington, D.C.
• Eastman, Timothy E., "Plasma Astrophysics". Plasmas International. (References, Parameters, and Research Centers links.)
• Heikkila, Walter J. "Elementary ideas behind plasma physics", from a Special Issue of Astrophysics and Space Science" Dedicated to Hannes Alfvén on 80th Birthday
• IEEE Xplore, IEEE Transactions on Plasma Science, 18 issue 1 (1990), Special Issue on Plasma Cosmology including A. L. Peratt, "Plasma cosmology", IEEE T. Plasma Sci. 18, 1-4 (1990).

Books

• H. Alfvén, Worlds-antiworlds: antimatter in cosmology, (Freeman, 1966).
• H. Alfvén, Cosmic Plasma (Reidel, 1981) ISBN 90-277-1151-8
• E. J. Lerner, The Big Bang Never Happened, (Vintage, 1992) ISBN 0-679-74049-X
• A. L. Peratt, Physics of the Plasma Universe, (Springer, 1992) ISBN 0-387-97575-6