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ScienceWeek
SCIENCE-WEEK
A Weekly Email Digest of the News of Science
A journal devoted to the improvement of communication
between the scientific disciplines, and between scientists,
science educators, and science policy makers.
September 25, 1998 -- Vol. 2 Number 39
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If you are a scientist you believe that it is good to find out
how the world works, that it is good to find out what the
realities are, that it is good to turn over to mankind at large
the greatest possible power to control the world... It is not
possible to be a scientist unless you believe that the knowledge
of the world, and the power which this gives, is a thing which is
of intrinsic value to humanity, and that you are using it to help
in the spread of knowledge, and are willing to take the
consequences.
-- J. Robert Oppenheimer (1904-1967)
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Contents of This Issue:
1. On Journal vs. Author Ownership of Scientific Papers
2. Minority Faculty and Academic Rank in Medicine
3. On the Sokal Hoax and Philosophical Extrapolations in Physics
4. Red Giant Stars and Constraints on the Hubble Constant
5. On the Asymmetry between Matter and Antimatter
6. On the Origin of Quantum-Mechanical Complementarity
7. Bio-Taxonomy: A Proposal for only Two Empires
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1. ON JOURNAL VS. AUTHOR OWNERSHIP OF SCIENTIFIC PAPERS
Fifty years ago, the publication of a scientific paper usually
did not involve any special contract between author and publisher
of the journal, and no signature transfer of copyright from
author to publisher occurred. In recent years, however, many
scientific journals have instituted a policy of requiring
signature transfer of copyright from author to publisher, with a
nonexclusive limited license returned to the author -- in other
words, the author effectively signs away ownership of his or her
creative effort to the journal. This is a rather odd development,
since it has never been the practice in commercial publishing,
where the usual arrangement for short creative work in magazines
(articles, short fiction, etc.) is a contractual license for one-
time serial rights to the publisher, with the author retaining
exclusive copyright -- in other words, the magazine buys the
right to publish the article once, and the author is free to sell
the article again. In the case of books, the standard practice in
commercial publishing is a contracted exclusive license to the
publisher, usually for a minimum of 35 years or the duration of
copyright, with ownership of the property and copyright retained
by the author, so that the author has recourse to unilateral
cancellation of the contract and its license to publish if the
contract is materially breached. There has always been some
confusion about this situation, since in most cases (for both
books and short works) the copyright notice is in the name of the
commercial publisher, and the copyright registration is by the
publisher, and the layman concludes that the publisher holds the
copyright. On the contrary, in most cases the commercial
publisher does not hold the copyright, but instead the publisher
merely holds a license to publish and has merely registered the
copyright as an agent of the author, and that is what is stated
in the TX copyright registration form. ... ... S. Bachrach et al
present a proposal for a radical change in the current usual
arrangements between authors of scientific papers and the
publishers of scientific journals, the authors of the report
making the following points: 1) Because the electronic world
offers many potential improvements to enhance traditional
publication, scientists, administrators, and federal science
policymakers must reconsider the means and support of
dissemination of the results of federally funded research. 2) The
authors of the report suggest that authors of scientific works
based on government-supported research should be free to
distribute those works as they see fit, via journals, electronic
postings, and other new modes. 3) Federal agencies that fund
research should recommend (or even require) as a condition of
funding that the copyrights of articles or other works describing
research that has been supported by those agencies remain with
the author. The authors of the report conclude: "Although
scientific journals have been important in all fields of science
for many years, we should not assume their continued unchanged
existence. Radical changes in the publication of scientific
research are already taking place and more are inevitable."
... ... In an editorial in the same issue of the journal where
the above report appears (*Science*), Floyd E. Bloom, Editor of
the journal, writes against the proposal by S. Bachrach et al,
with Bloom making the following points: 1) Copyright transfer is
critical to the process of communicating scientific information
accurately. 2) Neither the public nor the scientific community
benefits from the potentially no-holds-barred electronic
dissemination capability provided by today's Internet tools. 3)
Much information on the Internet may be free, but quality
information worthy of appreciation requires more effort than most
scientists could muster, even if able. Bloom concludes that the
current degree of investment in the scientific publication
process requires the assignment of copyright, and that "this
allows the society publisher to provide a stewardship over the
paper, to protect it from misuse by those who would otherwise be
free to plagiarize or alter it, and to expand the distribution of
information products for the benefit of society."
-----------
S. Bachrach et al (12 authors at 12 installations, US): Who
should own scientific papers?
(Science 4 Sep 98 281:1459)
QY: Steven Bachrach, Northern Illinois University 815-753-0446
Floyd E. Bloom (*Science*): The Rightness of Copyright.
(Science 4 Sep 98 281:1451)
QY: Floyd E. Bloom
-------------------
Summary by SCIENCE-WEEK 25Sep98
2. MINORITY FACULTY AND ACADEMIC RANK IN MEDICINE
Recent efforts to improve the representation of minority faculty
in US academic medicine have focused on increasing the number of
minority physicians who pursue academic careers. However, the
number of minority students entering US medical schools has
plateaued, despite efforts to achieve racial and ethnic diversity
in these schools. At the present time, only 3.9 percent of all US
medical faculty identify themselves as black, Native American,
Mexican American, or Puerto Rican, and these groups have been
classified as underrepresented in medicine compared to their
representation in the general population. Asian Americans are
currently not classified as underrepresented. ... ... A. Palepu
et al now report a study to determine whether minority faculty
were as likely as majority faculty to have attained senior rank
(associate professor or full professor) after adjusting for other
factors that typically influence promotion. The study consisted
of a self-administered mailed survey of US medical school faculty
using the Association of American Medical Colleges database, the
sample stratified by department, graduation cohort, and sex. Of
1807 respondents, 54 percent had attained senior academic rank.
The authors report that after adjusting for the medical school,
department, years as medical school faculty, number of peer-
reviewed publications, receipt of research grant funding,
proportion of time in clinical activities, sex, and tenure
status, the odds ratios relative to white faculty of holding
senior rank were 0.33 for black faculty, 0.36 for Hispanic
faculty, and 0.58 for Asian faculty. The authors conclude that
minority faculty are less likely than white faculty to hold
senior academic rank, and they suggest this finding is not
explained by potential confounders such as years as a faculty
member or measures of academic productivity. The authors further
suggest that "medical school deans and department heads need to
foster and provided greater support for the careers of minority
faculty to ensure their equitable representation at all levels in
academic medicine."
-----------
A. Palepu et al (6 authors at 2 installations, US): Minority
faculty and academic rank in medicine.
(J. Amer. Med. Assoc. 2 Sep 98 280:767)
QY: Anita Palepu
-------------------
Summary by SCIENCE-WEEK 25Sep98
3. ON THE SOKAL HOAX AND PHILOSOPHICAL EXTRAPOLATIONS IN PHYSICS
In the last quarter of this century, many fields outside of
physical science are apparently in the throes of epistemological
crises that are seen as originating in similar crises in physics
during the first quarter of the century. *Complementarity,
uncertainty, relativity, observer interactions -- the perceived
philosophical implications of these ideas have been imported into
the humanities and social sciences where they have rocked
foundations and produced what many critics view as an
intellectual babble. In 1996, theoretical physicist Alan Sokal
concocted an article consisting mostly of the ideations of so-
called "*postmodern" cultural studies of science, the article
concerned with "a transformative hermeneutics of quantum gravity"
and purporting to be an application of theoretical physics to
affirm the thrust of postmodern cultural studies of science in
the humanities and social sciences. The article was accepted and
*published by the journal *Social Text*, and shortly afterward,
in the journal *Lingua Franca*, Sokal revealed that his article
was a complete hoax and designed as a parody of contemporary
postmodern thought. In the academic furor that followed, Sokal's
article was characterized as "an ingenious exposure of the
decline of intellectual standards in contemporary academia," and
"a brilliant parody of the postmodern nonsense rampant among the
cultural studies of science." ... ... Writing in a physics
journal, M. Beller now outlines an argument that theoretical
physicists both past and present have had much responsibility for
what appear to be the nonsensical applications of theoretical
physics to the humanities and social sciences. The author makes
the following points: 1) The philosophical pronouncements
(several of which are quoted at length by Beller) of theoretical
physicists *Niels Bohr, *Max Born, *Werner Heisenberg, *Wolfgang
Pauli, and *Pascual Jordan deserve some of the blame for the
excesses of the postmodern critique of science. 2) Like the
deconstructionist *Jacques Derrida, Bohr was notorious for the
obscurity of his writing. Yet physicists relate to the
obscurities of Derrida and Bohr in fundamentally different ways:
Derrida is treated with contempt and Bohr is treated with awe,
his obscurity attributed to "depth and subtlety". 3) The author
points out that in a widely used compendium of papers in
theoretical physics published in 1983, there is an often cited
reprinted paper by Bohr whose pages are out of order, and yet no
complaints are heard and the mistake, which occurs in both
hardcover and softcover editions, is apparently rarely noticed.
3) The author points out that Bohr intended his philosophy of
complementarity to be an overarching epistemological principle
applicable to physics, biology, psychology, and anthropology.
Pauli argued for application of the quantum concept of reality to
unify science, religion, Jungian archetypes, and extrasensory
perception. Born stated that quantum philosophy would help
humanity cope with the postwar era. Heisenberg expressed the hope
that the results of quantum physics would transform cultural
life
by producing a renaissance of ideas. Jordan explored the "formal"
parallels between quantum physics and Freudian psychoanalysis. 4)
Beller points out that the philosophical pronouncements of Bohr
and other founders of quantum physics are not just an
anachronistic curiosity, since contemporary popular writings by
physicists and science writers continue to proclaim the victory
of Bohr's conception of reality, even though the Copenhagen
"orthodox" interpretation of quantum physics -- the abandonment
of causality and the ordinary conception of reality -- is not the
only possible interpretation of quantum physics, and ultimately
it might not even be the surviving one. 5) Beller concludes: "The
opponents of the postmodernist cultural studies of science
conclude confidently from the Sokal affair that 'the emperors
have no clothes.' But who, exactly, are all these naked emperors?
At whom should we be laughing?"
-----------
M. Beller (Hebrew University Jerusalem, IL): The Sokal hoax: at
whom are we laughing?
(Physics Today September 1998)
QY: Mara Beller, Hebrew University, Jerusalem IL.
-----------
Text Notes:
... ... *Complementarity: The idea that a fundamental particle is
neither a wave nor a particle, because these are complementary
modes of description (see below, Report #6).
... ... *postmodern: The term here refers to studies of how
contemporary concepts and methods are determined by historical or
ideological context. So, for example, one set of postmodern
questions concerning science involves the influences of Western
socio-political ideology on the structure and methods of Western
science. The general idea is the consideration of science as a
product of the culture from which it arises. But the term
"postmodern" has a loose usage, with one meaning in literature,
another in art, and a third in the social sciences.
... ... *published: Sokal's paper was published in *Social Text*
(Spring/Summer 1996, p.216), and then exposed immediately by
himself in *Lingua Franca* (May/June 1996, p.62).
... ... *Niels Bohr (1885-1962): Nobel Prize in Physics 1922. He
worked in the fields of atomic structure and nuclear fission, and
he proposed the doctrine of complementarity. As director of the
Institute of Theoretical Physics in Copenhagen from 1920 on, Bohr
was the head of what came to be called the Copenhagen School of
Quantum Mechanics, which produced what came to be called the
"Copenhagen orthodoxy" view of the implications of quantum
mechanics as applied in general to theoretical physics.
... ... *Max Born (1882-1970): Nobel Prize in Physics 1954. Did
fundamental work in quantum theory, particularly work linking the
wave function of the electron to electron distribution
probability. It was Born who apparently coined the term "quantum
mechanics". Born worked with Werner Heisenberg, one of his
students, in the development of the mathematical techniques of
matrix mechanics, an alternative to the Schroedinger wave
equation for calculation of the position and momentum of the
electron in the atom. From Born: "I am now convinced that
theoretical physics is actual philosophy."
... ... *Werner Heisenberg (1901-1976): Nobel Prize in Physics
1932. Developed quantum theory and formulated the uncertainty
principle, which concerns matter, radiation, and their reaction,
and which places absolute limits on the achievable accuracy of
measurement of physical phenomena in the quantum domain.
... ... *Wolfgang Pauli (1900-1958): Nobel Prize in Physics 1945.
Originated the exclusion principle, which states that in a given
system no two fermions (electrons, protons, neutrons, or other
elementary particles of half-integral spin) can be characterized
by the same set of quantum numbers. He also predicted the
existence of neutrinos.
... ... *Pascual Jordan (1902-1980): Worked with Born and
Heisenberg in the development of matrix mechanics. Also worked
in the relativistic quantum field theory of electromagnetism
(quantum electrodynamics).
... ... *Jacques Derrida (1930- ): A philosopher whose work spans
literary criticism, psychoanalysis, linguistics, and philosophy,
with an emphasis on the primacy of written text, the
referentiality of language, and the objectivity of conceptual
structures. Founded the school of criticism known as
"deconstruction".
-------------------
Summary & Notes by SCIENCE-WEEK 25Sep98
-------------------
Related Background:
DETAILS OF A PROPOSAL FOR A QUANTUM THEORY WITHOUT OBSERVERS
S. Goldstein, in the second part of a review of the current state
of the development of a quantum theory without observers, makes
the following points: 1) Several current quantum theories without
observers are completely well defined and hence provide a
conclusive refutation of Bohr's claim that such a theory is
impossible. 2) The paradoxes of quantum theory can be resolved in
a surprisingly simple way: by insisting that particles always
have positions and that they move in a manner naturally suggested
by the Schroedinger equation (e.g., the quantum mechanics of
David Bohm as amplified by John Bell). 3) The possibility of a
deterministic reformulation of quantum theory has been regarded
by many physicists as having been conclusively refuted,
particularly by the 1932 refutation of John von Neumann, but the
von Neumann proof is false, and subsequent "refutations" are not
convincing. 4) Bohmian mechanics is by far the simplest and
clearest version of quantum theory. 5) Although none of the
quantum theories without observers is Lorentz invariant, the
author believes such a theory is possible, and that the three
approaches of decoherent histories (which assumes the wave
function is not a complete description of a physical system),
spontaneous localization (which assumes spontaneous and random
collapse of wave functions), and Bohmian mechanics (which assumes
the wave function provides only an incomplete description of a
system and governs the motion of more fundamental variables) have
much to teach us about finding such a theory.
QY: Sheldon Goldstein, Dept. of Mathematics, Rutgers University
New Brunswick 908-932-8789.
(Physics Today April 1998 51:38) (Science-Week 24 Apr 98)
-------------------
Related Background:
ON QUANTUM THEORY WITHOUT OBSERVERS
One of the fundamental questions of physics is whether pure
states (i.e., states undisturbed by avoidable noise) are states
such that the outcome of every measurement can be exactly
predicted. Classical physics is based on the proposition that the
answer to the question is yes. Orthodox quantum mechanics is a
theory based on the proposition that the answer is no, and that
we can only make precise quantitative statements about probab-
ilities, the limitation due to an essential interaction between
the observer and that which is being measured.
... ... S. Goldstein (Rutgers University New Brunswick, US), in
the first of a two-part review, discusses the idea of quantum
theory without observers, and suggests that despite the claims of
most of the originators of quantum theory, the appeal at a fund-
amental level to observers and measurement, which is so prominent
in orthodox quantum theory, is not needed to account for quantum
phenomena. Referring to the classical Bohr-Einstein debate,
Goldstein says the debate has already been resolved in favor of
Einstein. What Einstein desired and Bohr held impossible -- an
observer-free formulation of quantum mechanics in which the
process of measurement can be analyzed in terms of more fund-
amental concepts, does in fact exist, and there are many such
formulations, several of which have the potential to become a
serious program for the construction of a quantum theory without
observers.
QY: Sheldon Goldstein, Rutgers University New Brunswick
908-932-8789.
(Physics Today March 1998 51:42) (Science-Week 20 Mar 98)
4. RED GIANT STARS AND CONSTRAINTS ON THE HUBBLE CONSTANT
In cosmology, according to the Hubble law that describes the
expansion of the Universe, a law first proposed by Edwin Hubble
in 1929, the apparent recession velocity of galaxies is
proportional to their distance from the observer, with the
proportionality factor denoted as H(sub0). This proportionality
factor is called the "Hubble constant", but in the *Big Bang
theory it varies with time and is really a parameter rather than
a constant. This important cosmological parameter is usually
measured in units of kilometers per second per megaparsec, which
is identified dimensionally as a variation of velocity with
distance. Assuming the Big Bang origin of the expansion, the
"Hubble time" is defined as the reciprocal of the Hubble
constant, and is the time required for the Universe to expand to
its present state, assuming the Hubble constant has remained
unchanged since the Big Bang. Determination of the Hubble time
has been far from unequivocal, with estimates of the Hubble time
ranging between 9 and 18 billion years, depending on various
measurements, models, assumptions, and so on. In the standard Big
Bang theory, the actual age of the Universe is always less than
the Hubble time, because the expansion was faster in the past.
... ... W.E. Harris et al now present a report of observations of
the brightest *red-giant stars in a *Virgo-cluster galaxy, and
the use of these observations to determine constraints on the
Hubble constant. The authors make the following points: 1) The
nearest large groups of *elliptical galaxies (in the Virgo and
*Fornax clusters) play a central role in determinations of the
Hubble constant, and hence the cosmological rate of expansion.
Because the relative distances between these two clusters and
more remote clusters are well known, absolute distance
determinations to Virgo and Fornax should establish the Hubble
constant for the local universe. 2) In addition, elliptical
galaxies reside predominantly in the cores of galactic clusters,
so distance calibrations for ellipticals should minimize the
uncertainties due to the possibly large extent of the clusters
along the line of sight. 3) The authors suggest that a powerful
and direct way of establishing such distances is to use the
brightest red-giant stars, which have nearly uniform
luminosities. 4) The authors report the direct observation of old
red-giant stars in a *dwarf elliptical galaxy in the Virgo
cluster. They determine a distance to this galaxy, and thus to
the core of the Virgo cluster, of 15 megaparsecs, from which they
estimate a Hubble constant of H(sub0) = 77 +- 8 kilometers per
second per megaparsec. Under assumptions of a *low density
Universe with the simplest cosmology, the authors suggest the age
of the Universe is no more than 12 to 13 billion years.
-----------
W.E. Harris et al (4 authors at 4 installations, CA US):
Constraints on the Hubble constant from observations of the
brightest red-giant stars in a Virgo-cluster galaxy.
(Nature 3 Sep 98 395:45)
QY: William E. Harris
-----------
Text Notes:
... ... *Big Bang theory: The Big Bang theory is the general
cosmological model that proposes that all matter and radiation in
the universe originated in an explosion at a finite time in the
past.
... ... *red-giant stars: A red giant star is a star in a late
stage of evolution, having exhausted the hydrogen fuel in its
core. It has a surface temperature of less than 4700 degrees
Kelvin and a diameter 10 to 100 times that of the Sun.
... ... *Virgo-cluster galaxy: The Virgo cluster is a giant
irregular cluster of galaxies in the constellation Virgo. It is
the nearest large cluster, and approximately 2500 galaxies have
been identified in it.
... ... *elliptical galaxies: These are galaxies that have no
disc component, the shape varying from almost circular to narrow
ellipses. The stars within elliptical galaxies are predominantly
old stars. Elliptical galaxies display the greatest variation in
mass, ranging down to extreme dwarfs (approximately 10^(6) solar-
masses.
... ... *Fornax: The Fornax system is a dwarf elliptical galaxy
in the Fornax constellation.
... ... *dwarf elliptical galaxy: A dwarf galaxy is one that is
unusually faint because of small size or low surface brightness
or both. Dwarf galaxies contain only a few million stars, and
they are usually difficult to observe against foreground stars
because they are almost completely transparent. Dwarf galaxies
apparently make up the bulk of the cosmic population.
... ... *low density Universe: The apparent mean density of
matter in the Universe, as determined from both theory and
observation, is a critical parameter that constrains the geometry
and future history of the Universe, and also the age of the
Universe.
-------------------
Summary & Notes by SCIENCE-WEEK 25Sep98
-------------------
Related Background:
EVOLUTION OF COSMIC STRUCTURE: LARGEST SIMULATION TO DATE
One of the important problems in cosmology is to explain the
present structure of the universe, and the evolution of that
structure from the primordial material that came into existence
following the Big Bang. Computer simulations are a significant
part of this research, the idea essentially to calculate from
first principles the properties of a model based on a particular
set of assumptions, compare the results of the calculations with
what is observed in the real universe, and thus, temporarily,
confirm or deny the usefulness of the assumptions that form the
basis of the model. This is the paradigm for most theoretical
model construction in all the sciences, and as a method it is
nothing unique to cosmology. In cosmology, however, the number of
interacting entities is enormous. A new simulation effort was
recently reported, evidently the largest simulation of cosmic
structure to date, the new effort involving consideration of a
simulated cosmos of a billion entities, each of which is
equivalent to about 10 galaxies. The work was carried out at the
Max Planck Institute for Astrophysics (Garching, DE), using a
512-processor Cray supercomputer, and reported at the end of last
month at a cosmology meeting in Paris by Jorg Colberg (MPI-
Astrophysics Garching, DE). The work was also presented a week
ago at the American Astronomical Society San Diego (US) meeting
by August Evrard (University of Michigan, US). This is apparently
the first simulation of how gravity could have gathered post-Big
Bang ripples into large meta-galactic structures -- walls,
clumps, filaments of galaxies -- filling all of space. Some
astrophysicists are saying this work marks a turning point in
numerical cosmology, and they expect this model universe to be a
powerful tool for interpreting data from large surveys of the
real sky. This simulation omits factors other than gravity, such
as pressure and radiation, that also govern galaxy formation. The
calculations have involved two different models, one a model
based on a mass density sufficient to stop cosmic expansion, and
the other (called the "lambda" model) based on a light-mass
universe that will expand forever. Apparently, it is the lambda
model that is producing structures more in agreement with
observations, although both models have difficulty accounting for
some of the more massive and distant galaxy clusters seen in the
real sky.
QY: Joseph Glanz (science_editors@aaas.org)
(Science 5 Jun 98 280:1522) (Science-Week 26 Jun 98)
-------------------
Related Background:
AN ARGUMENT FOR A LIGHTWEIGHT UNIVERSE
As mentioned in the previous report, a fundamental question in
cosmology is whether the expansion of the universe will continue
indefinitely (an open universe) or eventually cease (a closed
universe). According to the current analytical framework used to
describe the universe, the answer to this question depends on the
mass density of the universe. If the mass density is below a
certain calculated value, the "critical density", there is not
enough mass to provide the gravitational attractions necessary to
slow and halt the expansion. This critical density is equal to
1.9 x 10^(-29)H^(2) grams per cubic centimeter, which is
equivalent to approximately 10 protons per cubic meter. The (H)
indicated is the Hubble constant, the rate at which the expansion
velocity of the universe changes with distance. Often used is a
derived constant Omega(sub m), which is expressed in units of the
critical density, so that a value of Omega(sub m) = 1 means the
mass density is the critical density. The standard models of the
initial expansion of the universe (*inflation), as well as
general arguments not dependent on ad hoc adjustments of
cosmological parameters, predict a flat universe with the
critical density needed to just halt its expansion. But at the
present time, only a small fraction of the critical density has
been detected, even when all the unseen dark matter in galaxy
halos and clusters of galaxies is included. There is apparently
no reliable indication that most of the matter needed for closing
the universe does in fact exist. ... ... Bahcall and Fan
(Princeton University, US) present an analysis of the problem of
cosmic mass density. They propose that several independent
measures, especially those using the largest bound systems known
-- clusters of galaxies -- all indicate that the mass density of
the universe is insufficient to halt the expansion. They also
propose that a new method involving the evolution of the number
density of clusters with time provides the most powerful
indication so far that the universe has a subcritical density.
The authors suggest that various techniques reveal a consistent
picture of a lightweight universe with only 20 to 30 percent of
the critical density, and thus the universe may expand forever.
QY: Neta A. Bahcall (neta@astro.princeton.edu)
(Proc. Natl. Acad. Sci. US 26 May 98 95:5956)
(Science-Week 26 Jun 98)
-----------
Text Notes:
... ... *inflation: The inflationary model, first proposed by
Alan Guth in 1980, involves the idea that quantum fluctuations in
the time period 10^(-35) to 10^(-32) seconds following the
Big Bang were quickly amplified into large density variations
during the "inflationary" 10^(50) expansion of the universe in
that time frame.
-------------------
Related Background:
COSMOLOGY: OPEN, CLOSED, OR FLAT UNIVERSE?
Marc Kamionkowski (Columbia University, US) reviews current
research in cosmology, making the following points: 1) Determin-
ation of the geometry of the universe has been a central goal of
cosmology ever since Hubble discovered its expansion 75 years
ago. 2) The central question is whether the universe is a multi-
dimensional equivalent of a 2-dimensional surface ("flat"), a
sphere ("closed"), or a saddle ("open"). The geometry, in the
context of current theory and observations, determines whether
the universe will expand forever or eventually collapse. 3) Until
now, most astronomers have pursued the geometry by attempting to
measure the mass density of the universe. According to general
relativity, if the density is equal to, larger than, or smaller
than a critical density fixed by the expansion rate, then the
universe is flat, open, or closed, respectively. 4) Another
possibility is to look directly at the predicted observational
effects of a curved (open or closed) universe versus a flat
universe, and in particular at the angular power spectrum of the
cosmic microwave background. The authors suggest that in the near
future a new generation of experiments will provide substantial
advances in these observations, enabling more definitive
statements about the geometry of the universe, and that these
results will in turn provide clues to the new particle physics
required to understand the inflation phase following the Big Bang
origin of the universe.
QY: Marc Kamionkowski (kamion@phys.columbia.edu)
(Science 29 May 98 280:1397) (Science-Week 19 Jun 98)
-------------------
Related Background:
NEW CALCULATION OF HUBBLE CONSTANT APPEARS TO RESOLVE PARADOX
There has been a recent puzzle concerning the apparent age of
the universe and the apparent age of the oldest stars. Recent
data have suggested the universe is younger than the oldest
stars by a few billion years, which of course produces a
paradox. Now Simon Goodwin and John Gribbin at Sussex, working
with Martin Hendry in Glasgow, have devised and applied a new
method for estimating the age of the universe that apparently
resolves the paradox. The key to establishing the age of the
universe is the numerical value of the Hubble Constant (H). What
Goodwin, Gribbin, and Hendry have done is to deduce the value of
the Hubble Constant that must obtain if the average sizes of a
number of galaxies are to be statistically in harmony with the
average known sizes of other nearby galaxies whose distances are
now measurable with the Hubble Space Telescope. Once its distance
is known, the size of a galaxy can be measured by red shift
analysis. The new deduced result for the Hubble Constant puts
the age of the universe at 13 billion years, and since the
latest data for the oldest stars indicates their age at 12
billion years, the stellar chronological paradox is apparently
resolved.
(Communicated to SW by jgribbin@biols.susx.ac.uk 7 May 97)
5. ON THE ASYMMETRY BETWEEN MATTER AND ANTIMATTER
Antiparticles are homologs of elementary particles but with
opposite charge. The positron, for example, is the antimatter
particle homologous to the electron. Matter composed entirely of
antiparticles is called antimatter, and one of the important
questions in cosmology and theoretical astrophysics is the fate
of the antimatter proposed to have been created during the Big
Bang. The idea is that at one point there were equal amounts of
matter and antimatter, and the problem is that what is detected
is apparently an asymmetric universe with naturally occurring
antiparticles in places, but no antimatter in evidence. When
matter and antimatter connect, there is mutual annihilation.
In particle physics, the Standard Model is a theoretical
framework whose basic idea is that all the visible matter in the
universe can be described in terms of the elementary particle
types leptons and quarks and the forces acting between them.
There are 6 leptons: the electron, the muon, the massive tau
lepton, and the three associated neutrinos. A quark is a
hypothetical fundamental particle, having charges whose
magnitudes are one-third or two-thirds of the electron charge,
and from which the elementary particles may in theory be
constructed. ... ... H.R. Quinn and M.S. Witherell, in a review
of current ideas concerning the apparent asymmetry between matter
and antimatter, make the following points: 1) In 1999, new
accelerators will start searching for violations of *charge
parity reversal, effectively opening a window to physics beyond
the known. 2) An important question is whether the matter-
antimatter asymmetry is the result of a chance occurrence during
the birth of the Universe, or whether it is the inevitable result
of some asymmetry in the laws of nature. Current theory holds
that the excess of matter arises from fundamental disparities in
the behavior of matter and antimatter, these differences
constituting violations of the symmetry of charge parity
reversal. 3) The current Standard Model in particle physics
provides for the breaking of charge parity reversal symmetry, but
the amount of symmetry violation predicted by the model is too
small to explain the excess of matter in the Universe. 4)
Everything known about the elementary properties of matter is
encapsulated in the Standard Model, which describes the hundreds
of apparent particles and their interactions in terms of the
fundamental constituents of 6 quarks and 6 leptons. Current
theory requires an as yet unobserved *Higgs particle, whose
interactions are responsible for the masses of the quarks and
leptons, as well as for much of their behavior. 5) Despite its
great success in describing the behavior of matter, fundamental
questions remain concerning the Standard Model, particularly
questions concerning the mechanisms that determine the model's 18
parameters. Aspects of the theory that involve the Higgs particle
are all untested. The Higgs particle is believed to lie behind
most of the mysteries of the Standard Model, including the
violation of charge parity reversal symmetry. 6) The current
theoretical consensus is that particles and antiparticles were
equally numerous in the early Universe, but particles came to
dominate as the Universe expanded and cooled. The idea is that
originally the quantum field associated with the Higgs particle
was everywhere zero, but a bubble developed somewhere, a bubble
that would eventually comprise the Universe, the Higgs field
assumed its present non-zero value in the bubble, and the unequal
diffusion of matter and antimatter (because of charge parity
reversal violation conferring unequal diffusive properties) into
the Higgs bubble-Universe explains the current disparity in
matter-antimatter density. But calculations of the matter-
antimatter imbalance that might be produced by such a mechanism
have so far yielded results that are too small by many orders of
magnitude, and it thus appears that the Standard Model is
incomplete.
-----------
H.R. Quinn and M.S. Witherell (2 installations, US): The
asymmetry between matter and antimatter.
(Scientific American October 1998 279:76)
QY: Michael S. Witherell, Univ. of Calif. Santa Barbara, 805-893-
8000.
-----------
Text Notes:
... ... *charge parity reversal: The term "charge reversal"
refers to the production of opposite sign quantum numbers, the
result the changing of a particle to its antiparticle. The term
"parity reversal" refers to the mirror reflection of an object
and rotation by 180 degrees of all vectors associated with the
object. Charge reversal and parity reversal combined are called
charge parity reversal, and in 1964 it was discovered that *weak
interactions do not show charge parity reversal symmetry. The
discovery was made by the physicist Chieng-Shiung Wu (1913-1997),
who worked at Columbia University (US) from 1946 until her
retirement in 1981.
... ... *weak interactions: The weak force, one of the four
fundamental forces, occurs between leptons (particles without
internal structure, e.g., electrons, neutrinos) and hadrons
(particles with internal structure, e.g., neutrons and protons);
the weak force is responsible for radioactivity.
... ... *Higgs particle: Higgs fields (named after Peter W.
Higgs, University of Edinburgh, UK) constitute a set of
fundamental fields that induce spontaneous symmetry breaking. In
general, spontaneous symmetry breaking occurs in systems whose
underlying symmetry state is unstable. A Higgs particle is
associated with a Higgs field in the same way that a photon is
associated with the electromagnetic field.
-------------------
Summary & Notes by SCIENCE-WEEK 25Sep98
-------------------
Related Background:
ON COSMIC ANTIMATTER
... Tarle and Swordy (at 2 installations, US), review the
evidence concerning cosmic antimatter and the use of this
evidence as clues to some of the mysteries of astrophysics. The
existence of antimatter was first theoretically predicted by
P.A.M Dirac in 1928, and the first antiparticle, the positron,
was experimentally detected by Carl D. Anderson in 1932. The
first antiproton was created in 1955, and the first synthesis of
transient antihydrogen, merging positrons and antiprotons,
occurred in 1995. Astrophysicists believe most of the anti-
particles observed by upper atmosphere devices were created by
violent collisions of subatomic particles in interstellar space.
A number of balloon facilities have been launched to observe the
interaction of antiparticle cosmic rays with the outer portions
of the Earth's atmosphere, but to date no evidence of a natural
antiparticle heavier than an antiproton has ever appeared, and no
evidence of antimatter. But it is believed antistars and
antigalaxies might still lurk somewhere in the universe, billions
of light years from our own galaxy. The authors are associated
with the High Energy Antimatter Telescope (HEAT), a 2300 kilogram
device balloon-launched for the first time in 1994.
QY: Gregory Tarle, Dept. of Physics, Univ. of Michigan 313-764-
7433 (Scientific American April 1998)
-------------------
Related Background:
NEWLY OBSERVED POSITRON CLOUD SUGGESTS AGITATION IN OUR GALAXY
Our galaxy, the Milky Way, has always been considered to be a
relatively tranquil system. But now a team of astrophysicists
led by William Purcell (Northwestern University) and James
Kurfess (U.S. Naval Research Laboratory), using the orbiting
Compton Gamma Ray Observatory, have detected a cloud of
positrons, the antimatter equivalent of electrons, apparently
near the galactic center. There is speculation this cloud may be
related to a cluster of stellar explosions at the galactic
center about 10 million years ago. Not all astrophysicists agree
with this interpretation, however, and the evidence is yet too
scanty to delineate the complete nature and history of the
positron cloud. But there is apparently now agreement that our
galaxy is not as tranquil as was thought, and that considerable
turmoil, whether due to supernovas or black holes, existed at
the center. (Science 9 May 98)
-------------------
Related Background:
ANALYSIS INDICATES ABSENCE OF ANTIMATTER GALAXIES
Antiparticles are homologs of elementary particles but with
opposite charge. The positron, for example, is the antimatter
particle homologous to the electron. Matter composed entirely of
antiparticles is called antimatter, and one of the important
questions in cosmology and theoretical astrophysics is the fate
of the antimatter proposed to have been created during the Big
Bang. The idea is that at one point there were equal amounts of
matter and antimatter, and the problem is that what is detected
is apparently an asymmetric universe with no antimatter in
evidence. When matter and antimatter connect, there is mutual
annihilation with the emission of high energy gamma rays, so
astronomical gamma ray analysis may reveal the presence of
antimatter. Gamma-ray spectroscopy, which requires extra-
terrestrial instrumentation because of the impenetrability of the
Earth's atmosphere, is therefore an essential method in the
search for cosmic antimatter. Andy Cohen et al (3 authors at 3
installations, US, CH) report they have calculated the energy
that would have been emitted when primordial matter and
antimatter met and were annihilated, and when the results are
compared with actual measurements of the gamma-ray background,
what is present in the gamma-ray background radiation is only
one-fifth of what is expected. Astrophysicists are evidently
impressed with this work, which will be published in a few months
in the Astrophysical Journal.
QY: Sheldon Glashow, Harvard Univ. (617) 495-3752
(Science 10 Oct 97)
6. ON THE ORIGIN OF QUANTUM-MECHANICAL COMPLEMENTARITY
One of the most famous experiments in physics is the "two-slit"
experiment in which a beam of radiation simultaneously penetrates
two adjacent slits in a barrier with the formation of interfer-
ence patterns on the far side of the barrier, the interference
patterns produced by the wave character of the radiation entit-
ies. In physics, the *complementarity principle is the principle
that in nature any entity has two complementary aspects, particle
and wave, the two aspects related by momentum, energy, wave-
frequency, wavelength, and Planck's constant. In quantum theory,
the complementarity principle is manifested by wave-like behavior
(e.g., interference) occurring only when the different possible
paths that a particle can take are indistinguishable. A "which-
path" detector is any detector that determines the actual path
taken by a particle, the determination inevitably resulting in a
coupling of the particle to the measuring environment, which in
turn results in suppression of interference ("dephasing"). This
is usually explained in terms of Heisenberg's uncertainty
principle, which states the acquisition of spatial information
increases the uncertainty in the momentum of the particle, thus
destroying the interference. ... ... S. Duerr et al now report a
which-way experiment in an atom *interferometer in which the
"back action" of path detection on the momentum of the atom is
too small to explain the disappearance of the interference
pattern. Instead, the authors attribute the disappearance of the
interference pattern to correlations between the which-way
detector and the atomic motion, rather than to the uncertainty
principle. The authors suggest their results indicate that
complementarity is not enforced by the uncertainty relation.
-----------
S. Duerr et al (3 authors at the University of Konstanz, DE):
Origin of quantum-mechanical complementarity probed by a "which-
way" experiment in an atom interferometer.
(Nature 3 Sep 98 395:33)
QY: G. Rempe
-----------
Text Notes:
... ... *complementarity principle: Niels Bohr (1885-1962) first
introduced his idea of complementarity in a lecture delivered at
a meeting on 16 September 1927 at Lake Como (IT). The idea has
gone through many refinements and restatements, and is now
usually presented in terms of wave-particle duality. Bohr's
original idea was that complementarity is more fundamental than
the uncertainty principle.
... ... *interferometer: In general, an interferometer is any
instrument that detects the interference patterns of light
(radiation) split into two or more beams that are subsequently
combined again.
-------------------
Summary & Notes by SCIENCE-WEEK 25Sep98
-------------------
Related Background:
DEPHASING IN ELECTRON INTERFERENCE BY A WHICH-PATH DETECTOR
... Fermions (electrons, protons, neutrons) are particles that
obey the Pauli exclusion principle: i.e., no two fermions of the
same kind can occupy the same quantum state. The interferometer
in this report was a microscale device with dimensions of a few
microns and involving a 2-dimensional electron gas. ... ... Buks
et al (5 authors at Weizmann Institute of Science, IL) report the
dephasing effects of a which-path detector on electrons
traversing a double-path interferometer, and that varying the
sensitivity of the detector can affect the visibility of the
oscillatory interference signal, thereby verifying the
complementarity principle for fermions. This is apparently the
first study involving controllable dephasing via a which-path
detector. The authors suggest the technique may have other
applications to fundamental problems in quantum mechanics.
QY: M. Heiblum
(Nature 26 Feb 98) (Science-Week 13 Mar 97)
7. BIO-TAXONOMY: A PROPOSAL FOR ONLY TWO EMPIRES
The physicist confronting bio-taxonomy for the first time may
experience bewilderment: there are in excess of 30 million
species of life forms, the classification system is far from
simple, the system has some historically based confusions, and
the system is frequently redefined. Perhaps only the organic
chemist can feel a full empathy here, since organic chemistry is
faced with the similar problem of classifying millions of organic
chemical entities. A fundamental consideration is that in the
context of such a diversity of objects, a self-consistent
classification scheme is of extreme importance. At the present
time, in biology, there is a significant controversy concerning
primary categories, and that is the subject of this report. Two
main groups of life forms have been recognized for some time,
prokaryotes and eukaryotes. Prokaryotes are cells without a cell
nucleus and other membrane-bound organelles, and eukaryotes are
cells with a cell nucleus and other membrane-bound organelles.
(Organisms composed of eukaryote cells are also called
"eukaryotes"). For example, all bacteria are prokaryotes; all
complex animals, plants, etc., are eukaryotes. Fifteen years ago,
C.R. Woese (University of Illinois Urbana-Champaign, US) proposed
that the prokaryotes actually consist of two main groups, the
eubacteria and the archaebacteria, and that the differences
between these two groups are as great as the differences between
prokaryotes and eukaryotes, and that as a consequence a
tripartite primary scheme should be used, the primary categories
(kingdoms or empires) consisting of Eubacteria, Archaebacteria,
and Eukaryotes. Woese's differentiation of eubacteria and
archaebacteria was based on *habitats, cell wall constituents,
genome organization, and various aspects of protein synthesis
biochemical machinery, and during the past decade most biologists
have apparently accepted his categorization scheme. ... ... Now
Ernst Mayr (1904- ), a prominent biologist, proposes a rejection
of the Woese categorization and a return to a scheme involving
only 2 primary categories (empires), the Prokaryotes and
Eukaryotes. Mayr makes the following points: 1) A classification
scheme is essentially an information storage and retrieval
system, permitting the location of an entity with a minimum of
effort and loss of time, the objective optimally achieved by
arranging entities in a hierarchy of classes, ranked by degree of
similarity. 2) Evidence indicates that the archaebacteria are so
much more similar to the eubacteria than to the eukaryotes, that
their removal from the prokaryotes is not justified. The
eukaryotes differ from the prokaryotes (including the
archaebacteria) not only by the possession of a nucleus and
*mitosis but also by individual protein-rich chromosomes,
*meiotic sexuality (including viable regular cell fusions),
cellular organelles, highly complex sets of regulatory genes, and
all those genes that permit biodiversity... When a biologist
speaks of eukaryotes, he or she has in mind palms, oaks, and
orchids; mice, bats, and whales; and hummingbirds, chickens, and
ostriches. And this world of highly evolved eukaryotes is simply
an entirely different world from the world of the two kinds of
bacteria, the Prokaryotes. 3) Ranking, in any scheme of
classification of items (living or not), is by necessity based on
degree of difference. The two kinds of bacteria, in the vast
majority of their characteristics, are exceedingly similar to
each other and fundamentally so different from the eukaryotes
that they have to be ranked as a single *taxon, the prokaryotes,
different from the only other taxon of this rank, the eukaryotes.
Mayr suggests that only a two-empire classification correctly
reflects this structure of the living world.
-----------
E. Mayr (Harvard University, US): Two empires of three?
(Proc. Natl. Acad. Sci. US 18 Aug 98 95:9720)
QY: Ernst Mayr
-----------
Text Notes:
... ... *habitats: Many species of archaebacteria live in hot
acidic conditions, growing best at temperatures approaching 100
degrees centigrade. Because of this, it has been suggested the
lineage is more ancient than eubacteria, arising during
primordial conditions on Earth.
... ... *mitosis: In this context, division of the cell nucleus.
... ... *meiotic sexuality: A reduction division process whereby
a nucleus divides by 2 divisions into 4 nuclei, each containing
half the original number of chromosomes.
... ... *taxon: The organisms comprising a particular taxonomic
entity.
-------------------
Summary & Notes by SCIENCE-WEEK 25Sep98
-------------------
Related Background:
ON PROKARYOTES IN THE BIOSPHERE
Prokaryotes (bacteria) are unicellular life forms lacking a
membrane-bound nucleus, structured chromosomes, and complex
internal organization. They are invisible to the naked eye, but
they are an essential component of the Earth's biota. They
catalyze unique and indispensable transformations in the
biogeochemical cycles of the biosphere, produce important
components of the Earth's atmosphere, and represent a large
portion of life's genetic diversity. Although the abundance of
prokaryotes has been estimated indirectly, the actual number of
prokaryotes and the total amount of their cellular carbon on
Earth has never been directly assessed. ... ... Whitman et al (3
authors at University of Georgia, US) present an array of
calculations based on analysis of various habitats, and make the
following points: 1) The number of prokaryotes and the total
amount of their cellular carbon on Earth are estimated to be 4-6
x 10^(30) cells and 350-550 x 10^(15) grams of carbon,
respectively. The total amount of prokaryotic carbon is thus 60
to 100 percent of the estimated total carbon in plants, and
inclusion of prokaryotic carbon in global models will almost
double estimates of the amount of carbon stored in living
organisms. 2) In addition, the Earth's prokaryotes contain 85-130
x 10^(15) grams of nitrogen, and 9-14 x 10^(15) grams of
phosphorus, or about 10-fold more of these nutrients than do
plants, and represent the largest pool of these nutrients in
living organisms. 3) Most of the Earth's prokaryotes occur in the
open ocean, in soil, and in oceanic and terrestrial subsurfaces,
where the numbers of cells is of the order of 10^(29) to 10^(30).
4) The numbers of heterotrophic prokaryotes (bacteria that feed
on organic material) in the upper 200 meters of open ocean, the
ocean below 200 meters, and soil are consistent with average
turnover times of 6-25 days, 0.8 years, 2.5 years, respectively.
An uncertain estimate for the average turnover time of
prokaryotes in the subsurface is of the order of 1000 to 2000
years. 5) The cellular production rate for all prokaryotes on
Earth is estimated at 1.7 x 10^(30) cells per year and is highest
in the open ocean. The authors suggest that the large population
size and rapid growth of prokaryotes provides and enormous
capacity for genetic diversity, and that given the numerical
abundance and importance of prokaryotes in biogeochemical
transformations, the absence of detailed knowledge of prokaryotic
diversity is a major omission in our knowledge of life on Earth.
QY: William B. Whitman (whitman@uga.cc.uga.edu)
(Proc. Natl. Acad. Sci. US 9 Jun 98 95:6578)
(Science-Week 3 Jul 98)
-------------------
Related Background:
HYDROGEN HYPOTHESIS FOR THE FIRST EUKARYOTE
The classification system of bacteria is presently in a state of
flux due to new relationships continually revealed by molecular
biology, but the following nomenclature is generally accepted.
Eubacteria is a subkingdom of bacteria. All Eubacteria members
are prokaryotes, which means they lack a membrane-bound nucleus,
structured chromosomes, and complex internal organization. The
eukaryotes, in contrast, contain membrane-bound organelles,
including a nucleus. The archaebacteria (also called the Archaea)
are a subkingdom of bacteria considered to be ancient compared to
other bacterial kingdoms, and possibly the most ancient life
forms and the ancestors of all eukaryotes. They typically exist
in extreme environments, and include the methane-producing
bacteria (methanogens), the "salt-loving" bacteria (halophilic
bacteria), and the sulfur-acid tolerant thermoacidophilic
bacteria. In biology, "symbiosis" is an intimate and protracted
association of individuals of different species, and if both
participants receive benefits from the association, it is usually
called "mutualism". The term "autotrophic" means self-feeding,
and is used to characterize organisms that can synthesize all
their necessary nutrients from the oxidation of inorganic
compounds. Autotrophs are the primary producers of organic
compounds for all "heterotrophic" organism (i.e., organisms that
feed on other organisms). The term "anaerobic" refers to the
absence of oxygen. ... ... Martin and Muller (2 installations, DE
US) present a new hypothesis for the origin of eukaryotic cells,
the hypothesis based on the comparative biochemistry of energy
metabolism. Eukaryotes are proposed to have arisen through
symbiotic association of an anaerobic, strictly hydrogen-
dependent, strictly autotrophic archaebacterium (the host) with a
eubacterium (the symbiont) that was able to respire, but which
generated molecular hydrogen as a waste product of anaerobic
heterotrophic metabolism. The host's dependence upon molecular
hydrogen produced by the symbiont is proposed as the selective
principle that forged the common ancestor of eukaryotic cells.
The authors suggest their hypothesis generates numerous testable
predictions, and they firmly predict that evidence for a strictly
H(sub2)-dependent ancestry, and most probably a methanogenic
ancestry, of the host should ultimately be revealed by
comparative genomics. They also predict that anaerobic
heterotrophic habitats devoid of geological hydrogen may harbor
eukaryotes more primitive than known forms, the metabolism of
which should be accountable for by their hypothesis.
QY: William Martin
(Nature 5 Mar 98) (Science-Week 20 Mar 98)
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