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.

February 26, 1999 -- Vol. 3 Number 9

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Our loyalties are to the species and the planet.
We speak for Earth. Our obligation to survive is
owed not just to ourselves but also to that Cosmos,
ancient and vast, from which we spring.
-- Carl Sagan (1934-1996)

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Contents of This Issue:

1. An Evaluation of International Research
2. On Carbon in the Universe
3. On Edwin Hubble
4. Origin of Life: Role of Feldspar Tubular Microstructures
5. Polysaccharide Elasticity Governed by Chair-Boat Transitions
6. On Antigen Localization and Migration in Immunity

In Focus: On the Reality of Objects in Physics

-----------------------------------------------------------

1. AN EVALUATION OF INTERNATIONAL RESEARCH
Although arguments can be made for and against the significance
of studies of the quality of national scientific output,
particularly when such studies are based on counting papers
published and citations, such studies continue to be made and
published, and certainly in the context of considerations of
science policy, some data is perhaps better than no data
[Editor's note: see the first appended background report
concerning some problems inherent in citation studies].
... ... Jonathan Adams (University of Leeds, UK) now reports a
study of the scientific output of 7 industrialized countries:
United States, United Kingdom, Canada, France, Germany, Japan.
The study involved analysis of the journals database of the
Institute for Scientific Information, the two key variables
national origin of the paper and the number of times the paper is
cited in other papers. In terms of impact measures, the 7
countries rank as given above: US UK CA FR DE AU JP. The author
reports the US has the greatest output and citation share and has
a leading international impact, with England and Canada also
performing well across most fields. The output of France,
Germany, and Japan is significant, but their research impact is
less strong and is also more evidently focused in particular
fields. The author also reports the results reflect a pattern of
association between research competitiveness and the structure of
research management. Within Europe, there is complementarity in
research strengths with a bioscience lead in England and a
physical science/engineering lead in Germany and France. The
following lists the top 5 research fields for each country:
... US: Applied Mathematics, Physics, Chemistry, Metallurgy and
Materials, Electrical and Electronic Engineering.
... UK: Pharmacology/Pharmacy, Agriculture, Pure Mathematics,
Statistics and Operations Research, Veterinary Science.
... CA: Chemical Engineering, Food Science and Technology,
Clinical Dentistry, Library/Information Management, Chemistry.
... FR: Mineral and Mining Engineering, Chemical Engineering,
Applied Mathematics, Civil Engineering, Geography.
... DE: Applied Mathematics, Agriculture, Physics, Electrical and
Electronic Engineering, Mineral and Mining Engineering.
... AU: Mineral and Mining Engineering, Civil Engineering,
Chemical Engineering, Statistics and Operations Research,
Agriculture.
... JP: Electrical and Electronic Engineering, Nursing,
Metallurgy and Materials, General Engineering, Chemical
Engineering.
-----------
Jonathan Adams: Benchmarking international research.
(Nature 17 Dec 98 396:615)
QY: Jonathan Adams, Center for Policy Studies in Education,
University of Leeds, Leeds LS2 9JT, UK.
-------------------
Related Background:
SCIENTIFIC JOURNAL CITATION RATINGS OF US UNIVERSITIES
Measurement of the "impact" of scientific papers is an activity
that has burgeoned during the past 30 years as a result of the
possibility of computer tabulation and analysis of journal
references. The idea is that the number of citations of a
scientific paper in other scientific papers is a measure of its
impact on the scientific community, and the number of citations
of papers published by a research installation a measure of the
research impact of that installation. But there are difficulties:
few physicists who write papers in quantum mechanics, for
example, bother to mention the foundation papers by Planck,
Schroedinger, Heisenberg, etc., and few people who write papers
about genetics, DNA, and so on, bother to mention the foundation
paper by Watson and Crick. When one publishes in a particular
field, one assumes that the fundamental papers have been read by
everyone, even though there are no consensual rules about which
papers are "fundamental". Nevertheless, the measurement of
"impact" continues, a citation race rather than a horse race. The
Institute for Scientific Information (Philadelphia, US), which is
responsible for much of the impact measuring, has now ranked the
top 100 federally funded US universities in 21 separate fields,
measuring the "average number of times that papers from
researchers at each institution were cited in another paper."
Citations were apparently tracked in hundreds of scientific
journals, and here are the results, with universities ranked
according to impact in 4 different fields in the biological
sciences (top rank first): 1) Neuroscience: California Institute
of Technology, Stanford University, Johns Hopkins University. 2)
Immunology: Washington University St. Louis, Harvard University,
Stanford University. 3) Molecular Biology and Genetics:
Massachusetts Institute of Technology, Rockefeller University,
Harvard University. 4) Biology and Biochemistry: Duke University,
University of Texas Southwestern Medical Center Dallas, Harvard
University. The conclusion is apparently that Harvard University
is the leader in scientific impact in the biological sciences.
-----------
A. Adams (_Science_)
Harvard tops in scientific impact.
(Science 25 Sep 98 281:1936)
QY: Amy Adams 
-------------------
Summary by SCIENCE-WEEK [http://scienceweek.com] 16Oct98
-------------------
Related Background:
AN INSTANCE OF BUREAUCRATIC BUNGLING
It has been the tradition in science, perhaps since the 17th
century, to often report new research results in "letters". In
the early years of modern science, there were no journals, and
scientists reported their results to each other by correspond-
ence. In physics, there has been for some time an entire journal
devoted to such short reports of a few pages, and short reports
called "letters" are also found in journals in chemistry and
biology. The journal Nature has by tradition always published
such short reports, calling them either "letters" or
"correspondence". This week in Nature, there is a real "letter",
not a scientific report, from 27 scientists at the School of
Biological Sciences, Flinders University AU, informing us that
the Australian federal government's Department of Employment,
Education, Training, and Youth Affairs has decided that "letters"
to the journal Nature "are not an appropriate measure of
scientific output for the purposes of determining infrastructure
grants to Australian universities." The 27 authors point out that
the Watson-Crick model of the DNA double helix was first
published as a "letter" in Nature. Scientists in every scientific
discipline can cite instances of "letters" that were just as
significant. Apparently, what we have here is an example of how
difficult it is for government people untrained in scientific
research to possess any understanding of the dynamics over which
they want to exercise control. The bungling is comical; the
consequences are not comical at all.
-----------
(Nature 17 Jul 97) (Science-Week 25 Jul 97)


2. ON CARBON IN THE UNIVERSE
Carbon is a major factor in the evolutionary scheme of the
Universe because of its abundance and its ability to form complex
chemical entities. It is apparently also a key element in the
evolution of prebiotic molecules. The different forms of cosmic
carbon range from carbon atoms and carbon-bearing molecules to
complex solid-state carbonaceous structures, and evidence
gathered during the past decade has considerably enhanced our
understanding of the physical and chemical properties of carbon
materials in space. ... ...  Th. Henning and F. Salama (2
installations, DE US) present a detailed review of the subject,
the authors making the following points: 1) More than 75 percent
of the 118 *interstellar and circumstellar molecules identified
to date are carbon-bearing molecules, and one component of
interstellar dust is evidently carbonaceous. The cosmic evolution
of carbon from the interstellar medium into *protoplanetary disks
and *planetesimals, and finally into habitable bodies, is
intrinsic to the study of the origin of life. 2) Carbon plays an
important role in the physical evolution of the interstellar
medium because it is the main supplier of free electrons in
diffuse interstellar clouds, thus contributing to the heating of
interstellar gas. 3) The observation of unidentified ubiquitous
molecular and solid-state features in astronomical spectra, and
the realization that these features are linked to carbonaceous
materials, have resulted in major scientific progress in the past
decade. Laboratory and theoretical studies stimulated by these
astronomical observations have led to a better understanding of
the various forms of cosmic carbon such as polycyclic aromatic
hydrocarbons, carbon-chain molecules, carbon clusters, and
carbonaceous solids. These investigations have also led to the
detection of novel forms of carbon and laid the foundations for
the chemistry of *fullerenes. 4) The authors present the
following categorization of carbon in space:
... a) Carbon-rich circumstellar envelopes around *red giant and
*asymptotic giant branch (AGB) stars: CO, C(sub2)H(sub2), complex
hydrocarbons, gas-phase polycyclic aromatic hydrocarbons.
... b) Diffuse interstellar medium: C+, simple diatomic
molecules, gas-phase polycyclic aromatic hydrocarbons and carbon
chains.
... c) Dense interstellar medium: CO, complex hydrocarbons.
... d) Interstellar material in primitive meteorites: polycyclic
aromatic hydrocarbons.
5) The authors suggest that the widespread distribution of
complex organics in the interstellar medium has profound
implications for our understanding of a) the chemical complexity
of the interstellar medium, b) the evolution of prebiotic
molecules, c) the impact of this evolution on the origin and
evolution of life on early Earth through the exogenous delivery
(by cometary encounters and meteoritic bombardments) of prebiotic
organics.
-----------
Th. Henning and F. Salama: Carbon in the Universe.
(Science 18 Dec 98 282:2204)
QY: Th. Henning, Astrophysikalisches Institut und Universitats-
Sternwarte, Schillergabchen 2-3, D-07745, Jena DE.
-----------
Text Notes:
... ... *interstellar and circumstellar molecules: In this
context, an interstellar molecule is any molecule that occurs
naturally in clouds of gas and dust in space. In general, a
circumstellar molecule is any molecule that occurs in gas and
dust surrounding a star.
... ... *protoplanetary disks: These are dust disks surrounding
young stars; it is from these disks that planets presumably form.
... ... *planetesimals: Planetesimals are bodies with dimensions
of 10^(-3) to 10^(3) meters that are believed to form planets by
a process of accretion. The term "accretion" refers to an
aggregation, an increase in the mass of a body by the addition of
smaller bodies that collide and adhere to it, provided the
relative velocities are low enough for coalescence. As the mass
of the agglomerate increases, so does the rate of accretion, and
this accretion process is believed to generally occur in the form
of a disk. A stellar accretion disk is a swarm of dust grains
that evolve into planetesimals and then planets.
... ... *fullerenes: Fullerenes are large molecules composed
entirely of carbon, with the chemical formula C(sub n), where n
is any even number from 32 to over 100. They apparently have the
structure of a hollow spheroidal cage with a surface network of
carbon atoms connected in hexagonal and pentagonal rings.
... ... *red giant: A red giant star is a star in a late
stage of evolution. Having exhausted the hydrogen fuel in its
core, the star is burning elements heavier than hydrogen. It has
a surface temperature of less than 4700 degrees Kelvin and a
diameter 10 to 100 times that of the Sun.
... ... *asymptotic giant branch (AGB) stars: These are stars
that occupy a strip in the *Hertzsprung-Russell diagram that is
almost parallel to and just above what is called the "giant
branch" off the *Main Sequence. Stars evolve from the horizontal
H-R branch to the asymptotic giant branch when they have
exhausted the helium in their cores and are instead burning
helium in a shell.
... ... *Hertzsprung-Russell diagram: The Hertzsprung-Russell
diagram is a plot of stellar absolute magnitude against spectral
type, and is perhaps the most useful diagrammatic aid in
astrophysics. It allows the portrayal of the evolution of a star
as occurring along various paths in the diagram.
... ... *Main Sequence: The Main Sequence is a region on the
Hertzsprung-Russell diagram where most stars lie, including our
own Sun. The evolution of a star can be diagrammed as a movement
along the Main Sequence and an eventual branching off the Main
Sequence to regions associated with various types of old stars.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 26Feb99
-------------------
Related Background:
STELLAR CIRCULAR POLARIZATION AND BIOMOLECULAR HOMOCHIRALITY
Electromagnetic radiation involves the propagation of both
electric and magnetic forces, and at each point in a light beam,
there is a component electric field and a component magnetic
field, both of which oscillate in all directions perpendicular to
each other and to the direction in which the beam is propagated.
In plane-polarized light, the component electric field oscillates
as in ordinary light except that the direction of oscillation is
contained within a plane. Likewise, in plane-polarized light, the
component magnetic field oscillates within a plane, the planes in
question being perpendicular. Circularly polarized light has a
component electric field that varies in direction but not in
magnitude, so that the field traverses a spiral path in either a
clockwise or counterclockwise direction. In the laboratory, high
levels of *enantiomeric excess in *racemic substances can be
produced by asymmetric photolysis by circularly polarized light. 
Biological molecules exhibit extensive *homochirality (e.g.,
living systems use almost exclusively L-amino acids and D-
sugars), and this has been a puzzle since its discovery in the
19th century. It has been suggested that homochirality may be a
prerequisite for the origin of life, and a number of processes
have been proposed that may have produced enantiomeric excess in
prebiotic organic molecules, including the action of circular
polarization from the daylight sky, but these effects are
considered too small to account for homochirality. Another view
is that the origin of homochirality is extraterrestrial, and
apparent support for this view has been provided by the recent
discovery of an excess of L-amino acids in the *Murchison
meteorite. ... ... Bailey et al (8 authors at 4 installations, AU
UK FR JP) now report strong infrared circular polarization
resulting from dust scattering in *reflection nebula in an Orion
star formation region (OMC-1), and the authors suggest that
circular polarization at shorter wavelengths might have been
important in inducing chiral asymmetry in interstellar organic
molecules that could be subsequently delivered to the early Earth
by comets, interplanetary dust particles, or meteors. The authors
suggest this could account for the excess of L-amino acids found
in the Murchison meteorite, and could explain the origin of the
homochirality of biological molecules. The authors conclude:
"Whether a very high enantiomeric excess is a prerequisite for
the origin of life, or a very small effect is amplified in the
process, the ultimate source [of the excess] is likely to be of
extraterrestrial origin."
QY: Jeremy Bailey, Anglo-Australian Observatory, PO Box 296,
Epping, New South Wales 2121, AU.
(Science 31 Jul 98 281:672) (Science-Week 21 Aug 98)
-------------------
Related Background:
... ... *enantiomeric: In chemistry, an enantiomer is a compound
whose structure is not superimposable on its mirror image, the
compound being one of a pair of optical isomers, each of which
interacts differently with polarized light (i.e., shows optical
activity). A mixture of two optical isomers in equal amounts is
called a *racemic mixture, and racemic mixtures do not show
optical activity. A reactant or process that produces an
enantiomeric excess is simply a reactant or process that produces
or selects one enantiomer in excess over the other enantiomer.
... ... *racemic: (see *enantiomeric)
... ... *homochirality: Chirality is a property of certain
asymmetric molecules (or of any object), the property being that
the mirror images of the molecules cannot be superimposed one on
the other while facing in the same direction. Homochirality is
the preference of a process or system for a single optical isomer
in a pair of isomers.
... ... *Murchison meteorite: This meteorite, which fell near
Murchison AU in 1969, contains 8 amino acids and the nucleotide
bases adenine, guanine, and uracil.
... ... *reflection nebula: A bright cloud of interstellar gas
and dust that lies in the vicinity of a star or stellar group,
with the starlight scattered in all directions by the dust
grains, and the scattered light visible because of the high
density of the dust.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 21Aug98
-------------------
Related Background:
FIRST SYNTHESIS OF A LOW-MASS FULLERENE
Under appropriate non-equilibrium growth conditions, carbon atoms
form relatively stable hollow clusters of well-defined mass
number, collectively known as "fullerenes". The mass production,
purification, and condensation of such clusters into a molecular
solid is generally essential to full experimental characteriz-
ation. The initial discovery of C(sub60) in 1985, for example,
had to await a bulk synthesis method 6 years later before
detailed characterization of the molecule was possible. Gas-phase
experiments have indicated the existence of a wide range of
possible fullerene clusters, but beyond C(sub60) only a few pure
fullerene solids have been obtained, most notably C(sub70). Low-
mass fullerenes are of particular interest because their high
curvature and increased strain energy owing to adjacent
pentagonal rings could lead to solids with unusual intermolecular
bonding and electronic properties. ... ... Piskoti et al (3
authors at 3 installations, US) now report the synthesis of the
solid form of C(sub36) by the *arc-discharge method. They report
the development of purification methods that separate C(sub36)
from amorphous carbon and other fullerenes to yield saturated
solutions, thin films, and polycrystalline powders of the pure
solid form. The authors report observation of large increases in
the electrical conductivity of the solid on doping with alkali
metals, and they suggest that if C(sub36) could be made
sufficiently conducting -- either by doping or by structural
rearrangement (e.g., induced by pressure) -- one might expect
high-temperature superconductivity to be manifested.
QY: A. Zettl 
(Nature 25 Jun 98 393:771) (Science-Week 24 Jul 98)
-----------
Text Notes:
... ... *arc-discharge method: In the present instance, the
method involves an originally designed helium-environment arc-
discharge chamber, with an arc between two 0.25 inch-diameter
graphite electrodes, using a DC current of 100 amperes while
maintaining a 1 millimeter gap between the electrodes. Arcing is
maintained for several minutes, until a uniform carbon film of
approximately 10 microns thickness coats a removable metal
substrate 10 centimeters from the discharge region.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 24Jul98
-------------------
Related Background:
ORIGIN OF LIFE: THE PRESENT STATUS OF CHEMICAL THEORY
The essential question involved in the origin of what we call
life is how can order arise from disorder? At the present time,
this question is approached on two fronts: 1) study of the
principal features of self-organizing systems, systems in which
order does arise from disorder, systems in which order is indeed
demanded from disorder on thermodynamic grounds; and 2) study of
the detailed chemistry of such systems, the chemistry of
organization and the chemistry of components. In the case of
components, it is essential that appropriate self-organizing
components exist in the first place if they are to become self-
organized, and such candidate components are thus the focus of
much chemical research in this area. In 1953, the chemist Stanley
Miller reported what soon became a famous experiment. To water
under a gas mixture of methane, ammonia, and hydrogen, he added
an electrical discharge. After one week of continuous electrical
discharge, he found that a number of important biological
molecules, including amino acids, had been formed. Miller
proposed his experiment as a model for the conditions under which
the essential compounds necessary for life originated . The
Miller experiment was a watershed, and it began a new era of
experimentation and analysis of possible primordial components.
Coupled with this, were the new important discoveries by
astrophysicists of the presence of organic molecules in the
interstellar medium and in meteorites. In a review of origin of
life theories, P. Radetsky (Univ. of California Santa Cruz, US)
points out that the Miller theory is no longer the consensus
theory, that contemporary geologists believe the primordial
atmosphere consisted primarily of carbon dioxide and nitrogen,
which are less reactive than the gases in the Miller experiment,
and that the field is currently embroiled in controversy fueled
for the most part by an absence of hard fact.
QY: Peter Radetsky, Univ. of California Santa Cruz 408-429-4008
(Earth February 1988) (Science-Week 2 Jan 98)
-------------------
Related Background:
POSSIBLE EXPLANATION FOR LEVOROTATORY AMINO ACIDS IN BIOlOGY
A chiral molecule is an asymmetric molecule that cannot be super-
imposed on its mirror image. The molecule has two forms, called
enantiomorphs, that are mirror images of each other, the solut-
ions of which rotate the plane of polarized light in different
directions, left or right, making the enantiomers levorotatory or
dextrorotatory. Only levorotatory amino acids are present in
biological systems, and the reason for this is unknown. M. H.
Engel and S. A. Macko (University of Oklahoma, US; University of
Virginia, US) now report that individual amino-acid enantiomers
from the Murchison meteorite contain higher concentrations of the
nitrogen isotope N(sup15) compared to similar materials on Earth.
The authors suggest this confirms an extraterrestrial source for
an L-enantiomeric excess in our solar system that may predate the
origin of life on Earth.
QY: M. H. Engel [ab1635@ou.edu]
(Nature 18 Sep 97) (Science-Week 3 Oct 97)


3. ON EDWIN HUBBLE
At the time of his death, Edwin Hubble (1889-1953) was the most
eminent and celebrated observational astronomer in the world, a
man as well-known to the public as to the scientific community.
Essentially, Hubble made 3 major contributions during his
scientific career: 1) He provided the first evidence (1923) of
the existence of galaxies other than our own; 2) he proposed (in
the 1920s) a classification of galaxies as ellipticals, spirals,
and *barred spirals, a classification scheme still in use; 3) he
provided observational evidence (1928) for the recession of
galaxies (the expansion of the Universe), and he proposed (1929)
what is known as "Hubble's Law" relating the observed recession
rate of galaxies to their distance. The first and last of these
contributions have certainly been a most important part of the
foundation of 20th century cosmology. In much of his telescope
observational work, Hubble was assisted by Milton Humason (1891-
1972), an accomplished astronomer who was something of a Michael
Faraday in American astronomy: Humason had little formal
education and he first worked for Hubble as a janitor at the
Mount Wilson Observatory [*Note #1]. ... ... Gale E. Christianson
(Indiana State University) presents a biographical essay on
Hubble, the author making the following points: 1) Hubble was 6
feet 2 inches tall, weighed 190 pounds, constantly smoked a pipe,
favored a tightly-belted military trenchcoat, sported an English
accent acquired during his days as a Rhodes scholar at Oxford
University (where he studied law, not astronomy), and had a
special observatory wardrobe consisting of knickers, jodhpurs,
high-topped military boots, and a *Norfolk jacket. The author, in
fact, states that Hubble was disappointed when he arrived in
France during World War I only days before the November
armistice, "ending his dreams of leading men into battle." 2)
Hubble settled at the Mount Wilson Observatory in 1919, and
immediately began working with the 100-inch Hooker telescope. In
1923, working with the Hooker telescope, Hubble discovered
*Cepheid variable stars in the Andromeda *nebula M31 (later to be
called the Andromeda galaxy). Using the well-known period-
luminosity relationship established for Cepheid variables, Hubble
estimated the distance of the Andromeda galaxy as 300,000
*parsecs from Earth, a distance which apparently astounded
everyone. 3) Following the Andromeda galaxy work, in search of an
understanding of the formation and evolution of galaxies, Hubble
proposed what is now known as the "tuning fork diagram", a galaxy
classification scheme: the handle of the tuning fork consists of
an evolving sequence of elliptical galaxies (from spherical to
true elliptical), with one arm of the tuning fork diagramming the
evolution of spiral galaxies, and the other arm of the tuning
fork diagramming the evolution of the "barred" spiral galaxies.
4) In 1928, Hubble and Humason began a systematic study of the
*redshifts of galaxies, and in 1929 this resulted in the proposal
that the distances and recessional speeds of the nebulae
(galaxies) are in direct proportion to each other ("Hubble's
Law"): double the distance to a galaxy and the speed of recession
doubles; triple the distance and the speed triples [*Note #2]. 5)
In 1931, Einstein visited Hubble in Pasadena, and apparently when
Hubble was working at the observatory, Grace Hubble, Edwin
Hubble's wife, drove Einstein to his meetings and appointments.
The author concludes: "He [Einstein] was silent sometimes, and
sometimes he would talk in French or English, for Grace knew no
German. One afternoon he broke his silence to say, 'Your
husband's work is beautiful.'" [Editor's note: It was Hubble's
demonstration of the apparent expansion of the Universe that
caused Einstein to call his rather ad hoc introduction of the so-
called "cosmological constant" into his relativity equations "the
greatest aesthetic blunder of my life." Einstein's relativity
model proposed a non-expanding Universe essentially held static
by the cosmological constant term. In addition to the background
material below, considerably more background material can be
found in various SW Focus Reports located at the SW website:
[http://scienceweek.com/swfr.htm]].
-----------
Gale E. Christianson: Mastering the Universe.
(Astronomy February 1999)
QY: Gale E. Christianson, Indiana State University 812-237-2121.
-----------
Text Notes:
... ... *barred spirals: In general, a barred spiral galaxy is a
type of galaxy with spiral arms extending from an almost
rectangular or cigar-shaped bar of stars across its central
region.
... ... *Norfolk jacket: From Norfolk UK (c. 1866). A loose-
fitting belted single-breasted jacket with box pleats.
... ... *Cepheid variable stars: These are variable stars that
pulsate periodically, expanding and contracting with as much as a
30% change in size in each cycle, with a typical average luminos-
ity about 10,000 times that of our Sun. In 1912, Henrietta Swan
Leavitt discovered a simple relationship between the period of
light variation and the absolute magnitude of a Cepheid variable.
This relationship, called the "period-luminosity law", enabled
the calculation of distances to the stars in our own galaxy and
to the stars in other galaxies. In 1952 it was discovered that
there are two types of Cepheid variables, which meant an error
had been introduced in the earlier calculations of distances, and
when the correction was made, the apparent size of the universe
abruptly doubled. During 1908-1912, Leavitt (1868-1928), a
graduate of Radcliffe College on the staff of the Harvard
Observatory, discovered 2400 variable stars, doubling the number
known in her time. In the early years of stellar spectroscopy,
particularly at the Harvard Astronomical Observatory, nearly all
the data was catalogued and analyzed by female astronomers,
called "computers", who were forbidden because of their sex to
use the telescopes. It is an irony of the social history of
science that the work of such female astronomers as Henrietta
Swan Leavitt and Annie Jump Cannon (1863-1941) came to be of
greater significance than the work of many of the male
astronomers who considered these female astronomers to be no more
than menial assistants.  
... ... *nebula: Before Hubble, all of the fuzzy astronomical
objects that appeared in telescopes, many of which are now known
to be galaxies, were thought to be clumps of gas and dust. There
are indeed clumps of gas and dust everywhere in the Universe, and
they are correctly termed "nebulae". But since the work of
Hubble, which means since the 1920s, the use of the term "nebula"
for a galaxy is obsolete and incorrect.
... ... *parsecs: 1 parsec equals 3.262 light-years, or 30.86 x
10^(12) kilometers.
... ... *Note #1: In general, the Hubble tuning fork diagram
contains 10 galaxy categories. An 11th category, "irregular
galaxies", is usually diagrammed as an extending tine between the
two tuning fork arms. The result is a 3-prong "pitchfork"
diagram, rather than a "tuning fork" diagram.
... ... *redshifts: Redshift (symbol: z) is a lengthening of the
wavelengths of electromagnetic radiation from a source caused
either by the movement of the source (Doppler effect) or by the
expansion of the universe (cosmological redshift). Redshift is
defined as the change in wavelength of a particular spectral line
divided by the unshifted wavelength of that line. Large redshifts
imply large radial velocities (which imply large distances,
according to current cosmological theory), but at redshifts
greater than about 0.2 there is a relativistic divergence from a
linear relation. A redshift of 4.0 corresponds to an object
receding with a radial velocity 92% that of the velocity of
light. The largest astrophysical redshifts so far observed are of
the order of z = 4.9. The furthest galaxy on record is at a
redshift z=4.92), which implies a distance of approximately 13
billion light years.
... ... *Note #2: Humason measured the speed of recession of
approximately 800 galaxies. In 1956, three years after the death
of Hubble, Humason and others refined Hubble's Law, making the
proportionality constant (Hubble constant) in the relationship
between recession velocity and distance essentially time-
dependent. The "Hubble constant" is thus more properly called the
"Hubble parameter".
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 26Feb99
-------------------
Related Background:
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


4. ORIGIN OF LIFE: ROLE OF FELDSPAR TUBULAR MICROSTRUCTURES
Mineral surfaces may have been important during the emergence of
life on Earth, since the assembly of the necessary complex
biomolecules by random collisions in dilute solutions appears
implausible. Most silicate mineral surfaces are hydrophilic and
organophobic and unsuitable for catalytic reactions, but some
silica-rich surfaces of partly dealuminated *feldspars and
*zeolites are organophilic and potentially catalytic.
... ... I. Parsons et al (3 authors at 2 installations, UK US)
present an analysis of the possible involvement of weathered
feldspar surfaces in the origin of life on Earth, the authors
making the following points: 1) Weathered alkali feldspar
crystals from granitic rocks at Shap (northwest England) contain
abundant tubular etch pits, typically 0.4-0.6 microns wide,
forming an orthogonal honeycomb network in a surface zone 50
microns thick, with 2 to 3 x 10^(6) intersections per square
millimeter of crystal surface. 2) Surviving *metamorphic rocks
demonstrate that granites and acidic surface water were present
on the Earth's surface by 3.8 billion years ago. 3) By analogy
with Shap granite, honeycombed feldspar has considerable
potential as a natural catalytic surface for the start of
biochemical evolution. With biomolecules available as a result of
catalysis of amino acids, etc., the honeycomb would have provided
access to various mineral inclusions in the feldspar,
particularly apatite and oxides, which contain phosphorus and
transition metals necessary for the energy metabolism of living
forms. 4) The organized environment of honeycombed feldspar would
have protected complex molecules from dispersion into dilute
solutions, from hydrolysis, and from ultraviolet radiation. 5)
The sub-micrometer tubular structures presently observed in the
honeycomb might have acted as rudimentary cell walls for proto-
organisms, which ultimately evolved a lipid lid that gave further
shelter from the hostile outside environment. A lid would finally
have become a complete cell wall permitting detachment and
flotation in primordial "soup". 6) Observations indicate that
etch features on weathered alkali feldspar from Shap match the
shape of overlying soil bacteria. The authors conclude: "Is it
purely coincidence that the dimensions of the vertical etch-
tubes, particularly near their mouths, and the widths of the
grooves on highly weathered feldspar surfaces, match exactly the
dimensions of most modern soil bacteria? Or are the dimensions of
these exceedingly abundant organisms a distant echo of the
reactors in which the first life evolved?"
-----------
Editor's note: In addition to the background material below,
further background can be found in the SW Focus Reports "Origin
of Life" and "Origin of Life (2)" at
[http://scienceweek.com/swfr009.htm] and
[http://scienceweek.com/swfr040.htm]
-----------
I. Parsons et al: Biochemical evolution II: Origin of life in
tubular microstructures on weathered feldspar surfaces.
(Proc. Natl. Acad. Sci. US 22 Dec 98 95:15173)
QY: Joseph V. Smith [smith@geol.uchicago.edu]
[Editor's note: A brief of the first paper appears below.]
-----------
Text Notes:
... ... *feldspars: (felspars) These are aluminosilicates with a
framework structure, and consisting of sodium, potassium, and
calcium. This is the most abundant mineral group in the Earth's
crust.
... ... *zeolites: Hydrated aluminosilicate minerals with a
framework structure enclosing cavities occupied by large ions and
water molecules, both with substantial mobility in the framework.
Among other places, zeolites occur in fissures in basic volcanic
rocks.
... ... *metamorphic rocks: A metamorphic rock is an aggregate of
minerals formed by the recrystallization of pre-existing rocks in
response to a change of pressure, temperature, or volatile
content.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 26Feb99
-------------------
Related Background:
ORIGIN OF LIFE: PRODUCTION OF PEPTIDES ON INORGANIC SURFACES
The primordial process responsible for the activation of amino
acids and the formation of peptides under primordial conditions
is one of the great riddles of the origin of life. ... ... Huber
and Wachterschauser (Technische Universitat Munchen, DE) now
report that in experiments modeling volcanic or hydrothermal
settings, amino acids were converted into their peptides by use
of coprecipitated (Ni,Fe)S and CO in conjunction with H(sub2)S
(or CH(sub3)SH) as a catalyst and condensation agent at 100
degrees centigrade and pH 7 to 10 under anaerobic aqueous
conditions. The amino acids involved in the experiments were
phenylalanine, tyrosine, and glycine. The authors suggest their
results demonstrate that amino acids can be activated under
geochemically relevant conditions, and that the results support a
thermophilic origin of life with a primordial surface metabolism
on transition metal sulfide minerals. They further suggest that a
continuously recycling library of peptides was generated on the
surfaces of a library of (Fe,Ni)S structures, and that the
results raise the possibility that CO and Ni had a much greater
role in the primordial metabolism than in any of the known extant
metabolisms. They point out that all known extant organisms are
found in habitats with low activities of CO and Ni, and they
suggest this could explain why organisms resorted to the
formation of CO from CO(sub2) and to the elimination of nickel
from many enzymes.
QY: Gunter Wachterschauser, Tal 29, D-80331 Munchen, DE.
(Science 31 Jul 98 281:670) (Science-Week 28 Aug 98)
-------------------
Related Background:
BIOCHEMICAL EVOLUTION: POLYMERIZATION ON MINERAL SURFACES
J. Smith (University of Chicago, US) proposes a conceptual
framework for consideration of the origins of replicating
biopolymers. Although extended Darwinian natural selection
coupled with Mendel-Watson-Crick genetic inheritance/mutation
provides a plausible framework for integrating the patchy
paleontological record with the increasingly complex biochemical
zoo of the present Earth, the actual chemical beginning of "life"
still poses major challenges. How could the first replicating and
energy-supplying molecules have been assembled from simpler
materials that were undoubtedly available on the early proto-
continents? Catalysis at mineral surfaces might generate replic-
ating biopolymers from simple chemicals supplied by meteorites,
volcanic gases, and photochemical gas reactions. But many ideas
are implausible in detail because the proposed mineral surfaces
strongly prefer water and other ionic species to organic ones.
The molecular sieve silicalite (Union Carbide; = Al-free Mobil
ZSM-5 zeolite) has a 3-dimensional 10-ring channel system whose
electrically neutral silicon-oxide surface strongly adsorbs
organic species over water, and the ZSM-5 type zeolite mutinaite
has recently been found in Antarctica. The author proposes that
zeolites with similar structures may have existed on the surface
of Earth during its life-origin phase, and that polymer migration
along weathered silicic surfaces of micrometer-wide channels of
feldspars might have led to assembly of replicating catalytic
biomolecules and perhaps primitive cellular organisms. The author
suggests that weakly metamorphosed Archaean rocks might retain
microscopic clues to the proposed mineral adsorbent/catalysts,
and that other frameworks are also possible, including ones with
laevo/dextro one-dimensional channels.
QY: Joseph V. Smith (smith@geol.uchicago.edu)
(Proc. Natl. Acad. Sci. US 31 Mar 98 95:3370)
(Science-Week 8 May 98)


5. POLYSACCHARIDE ELASTICITY GOVERNED BY CHAIR-BOAT TRANSITIONS
Many common biologically important polysaccharides contain
pyranose rings made of 5 carbon atoms and 1 oxygen atom. These
rings occur in a variety of cellular structures, where they are
often subjected to considerable *tensile stress. The
polysaccharides are believed to respond to this stress by
*elastic deformation, but the underlying rearrangements allowing
such a response remain unclear. It is typically assumed, however,
that the pyranose ring structure is inelastic and locked into a
*chair-like conformation. ... ... P.E. Marszalek et al (4 authors
at Mayo Foundation, US) now report single-molecule *atomic force
microscopy measurements on individual polysaccharides that
identify the pyranose ring as the structural unit controlling the
elasticity of the molecule. The authors report that in particular
they find the *enthalpic component of the polymer elasticity of 
*amylose, *dextran, and *pullulan is eliminated once their
pyranose rings are cleaved. The authors suggest their
observations indicate that the elasticity of these
polysaccharides results from a force-induced elongation of the
ring structure and a final transition from a chair-like to a
boat-like conformation. The authors further suggest that the
force-induced deformation they are reporting plays an important
role in accommodating mechanical stresses and modulating ligand
binding in biological systems.
-----------
P.E. Marszalek et al: Polysaccharide elasticity governed by
chair-boat transitions of the glucopyranose ring.
(Nature 17 Dec 98 396:661)
QY: Julio M. Fernandez [fernandez.julio@mayo.edu]
-----------
Text Notes:
... ... *tensile stress: In this context, "stress" is defined as
the force per unit area on a body that tends to cause it to
deform, and "tensile stress" is an axial force per unit area
applied to a body that tends to extend it.
... ... *elastic deformation: In this context, elasticity is the
property whereby a molecule changes its shape due to imposed
forces, but recovers its original configuration when the forces
are removed.
... ... *chair-like conformation: (chair-like form; chair form)
The term "conformation" is usually restricted to dynamic spatial
arrangements of atoms or groups in a molecule that may be in
equilibrium with other conformations. Under usual conditions, no
single conformation constitutes a discrete and isolatable
substance (in contrast to configurational isomers). The "chair"
conformation is a particular nonplanar conformation of a cyclic
molecule with more than 5 atoms in the ring (e.g., the chair form
of cyclohexane). The alternative "boat" form (which can also be
assumed by e.g., cyclohexane) is relatively unstable. The two
forms can be visualized as follows (backbone continuous in each
case:
               \__  chair       \__/  boat
                  \ 

... ... *atomic force microscopy: An atomic force microscope is a
type of microscope in which a small probe, consisting of a tiny
chip of diamond, is held on a spring-loaded cantilever in contact
with the surface of a sample. The probe is moved slowly across
the surface, and the tracking force between the tip and the
surface is monitored. The probe is raised and lowered so as to
keep this force constant, and a profile of the surface is thus
produced. Since the instrument can be used with electrically
nonconducting samples, it is useful for biological specimens.
... ... *enthalpic component: Enthalpy, usually denoted as H, is
a thermodynamic state variable defined by H = U + PV, where U is
the internal energy and P and V are the pressure and volume
respectively. For any process which occurs at constant pressure,
the heat absorbed or evolved is equal to the enthalpy change if
the only work is pressure/volume work.
... ... *amylose: A linear polymer component of starch.
... ... *dextran: Any of several polysaccharides that yield
glucose units on hydrolysis.
... ... *pullulan: An extracellular glucan produced by certain
yeast and other fungi. In general, a "glucan" is any
polysaccharide consisting solely of glucose residues.
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 26Feb99


6. ON ANTIGEN LOCALIZATION AND MIGRATION IN IMMUNITY
Aside from the important clinical implications, the cell biology
and molecular biology of the human immune system is a complex and
challenging scientific puzzle. The immune response involves a
variety of cells, a variety of mechanisms, and an elaborately
orchestrated repertoire of interactions whose details are still
far from clear. ... ... T.E. Starzl and R.M. Zinkernagel (2
installations, US CH) present a review of the relation between
*antigen migration or localization and immune response or immune
tolerance, the authors making the following points: 1) The immune
system reacts similarly against *cytopathic microorganisms and
noncytopathic microorganisms, but with different consequences. a)
Cytopathic microorganisms provoke a full immune response, first
of the *nonspecific (innate) immune system, and then of the
*specific (adaptive) immune system, the two systems mobilized to
eliminate the cell-damaging microorganisms quickly and completely
and without regard for immune-mediated destruction of host
tissues. b) In contrast to cytopathic microorganisms, less
cytopathic or noncytopathic microorganisms can be accommodated in
ways that allow the host and pathogen to coexist. Intracellular
microorganisms are primarily controlled by immune system cells
that recognize chemical changes in the surfaces of infected
cells. The immune response in the case of less cytopathic or
noncytopathic microorganisms is apparently subdued (various
degrees of antigen-specific nonreactivity) and unnecessary damage
by the immune response to normal or infected tissue is thus
prevented. 2) The hyperacute rejection of *xenografts apparently
involves mechanisms of predominantly innate immunity, including
*complement-dependent cell destruction and other mechanisms based
on *cross-reactive natural antibodies. The best characterized
target antigen on the cells of rejected xenografts is the cell
surface carbohydrate *epitope alpha(1-3)galactose. Since this or
similar substances are also found in numerous bacteria, protozoa,
and viruses, these microorganisms are likely to be responsible
for the preexisting natural antibodies involved in the response
to xenografts. 3) In the case of *allografts, the evidence
indicates that immune rejection of such grafts is the
physiological equivalent of rejection of infected host cells,
with donor *lymphocytes (which accompany the grafted tissue)
reacting against host tissue cells, and host lymphocytes reacting
against donor tissue cells. 4) In general, because *lymphoid
organs are critical sites for the induction of the response
against all antigens, the resulting immune reactions can be
correlated with both the routes of spread and the eventual
localization of antigen... Also in general, antigens that do not
enter organized lymphoid tissue do not induce an immune response
(called "immune indifference"): long term survival is possible
for microorganisms localized in non-lymphoidal sites. 5) The
authors propose that the migration and localization of antigen
are the governing factors in immunological responsiveness or
unresponsiveness against infections, tumors, *self, xenografts,
and allografts. The authors also propose that under both
circumstances (responsiveness or unresponsiveness), an immune
response can be construed as a balance between potentially
reactive lymphocytes and the composition, quantity, kinetics, and
distribution of antigen (foreign or self) in the host.
-----------
Editor's note: In addition to the background material below, see
the SW Focus Report "Immunology: Biological and Medical Aspects"
accessible at [http://scienceweek.com/swfr037.htm].
-----------
T.E. Starzl and R.M. Zinkernagel: Antigen localization and
migration in immunity and tolerance.
(New England J. Med. 24 Dec 98 339:1905)
QY: Thomas E. Starzl, Falk Clinic 5C, 3601 Fifth Ave.,
Pittsburgh, PA 15213 US.
-----------
Text Notes:
... ... *antigen: Any chemical entity that activates an immune
response, especially an entity originating outside the body. In
many cases, the response of the immune system is the production
of "antibodies" specific to the antigen. (In general, an antibody
is any molecule designed to specifically interact with a
particular antigen.)
... ... *cytopathic microorganisms: In general, a "cytopathic"
microorganism is any microorganism (bacterium, virus, protozoan,
fungus, etc.) that provokes a cellular dysfunction. Some
cytopathic microorganisms are lethal, others are not.
... ... *nonspecific (innate) immune system: In general, innate
immunity is a resistance manifested by a species (or by races,
families, etc.) that has not been immunized by previous infection
or vaccination. For the most part, the body mechanisms
responsible for innate immunity are not well understood, but they
are apparently different from the mechanisms for acquired
(adaptive) immunity. In general, innate immunity is nonspecific
and is not stimulated by specific antigens.
... ... *specific (adaptive) immune system: (acquired immunity
system) This refers to the system responsible for resistance
resulting from previous exposure to an infectious agent or
antigen. "Active" acquired immunity results from infection or
vaccination; "passive" acquired immunity results from transfer of
antibodies, including mother-to-fetus transfer. Passive cell-
mediated immunity, produced by the transfer of living lymphoid
cells from one individual to another, is sometimes called
"adoptive" immunity.
... ... *xenografts: A xenograft is a graft transferred from an
individual of one species to an individual of another species.
... ... *complement: (alexin) In this context, complement is a
group of proteins in the bloodstream that assist the immune
system in the destruction of invading microorganisms. At 20
distinct proteins are involved. In general, the activation
products of complement components cause lysis of antigenic cells
and facilitate the destruction of antigenic cells by immune
system phagocytic ("cell-eating") cells.
... ... *cross-reactive natural antibodies: In general, a cross-
reacting antibody is any antibody that is able to react with an
antigen that did not specifically stimulate its production.
Cross-reactions may be weaker than the reaction of the antibody
with its specific antigen.
... ... *epitope: The term "epitope" refers to the region of an
antigen molecule responsible for its specificity in an
antigen-antibody interaction: the epitope is recognized by the
antigen-binding site of a specific antibody molecule.
... ... *allografts: An allograft is any graft from one
individual of a species to another individual of the same
species.
... ... *lymphocytes: These are a type of leukocyte (white blood
cell) responsible for the immune response. There are two classes
of lymphocytes: 1) the B-cells, which when presented with an
activating chemical entity (antigen) change into antibody
producing plasma cells; 2) the T-cells, which interact directly
with foreign invaders such as bacteria and viruses. There are
also forms of T-cells that are involved with B-cell activation. 
... ... *lymphoid organs: The lymphatic system is a complex
network for the distribution of lymph fluid (which is similar to
blood plasma -- blood without red cells), and "lymphoid organs"
are any organs which are part of or in contact with the lymph
system.
... ... *self: In this context, an individual's own cell
components as contrasted with non-self or "foreign" constituents.
There is apparently a basic immune mechanism for recognizing self
from non-self, but the mechanism is unknown. The recognition
mechanism protects an individual from immunological attack on the
individual's own antigenic constituents (self antigens as opposed
to foreign or non-self antigens).
-------------------
Summary & Notes by SCIENCE-WEEK [http://scienceweek.com] 26Feb99
-------------------
Related Background:
ON HOMEOSTASIS AND SELF-TOLERANCE IN THE IMMUNE SYSTEM
Parijs and Abbas (Harvard University, US) review the principal
control mechanisms for 1) maintaining homeostasis after active
immune responses to foreign antigens; and, 2) preventing or
aborting responses to self-antigens. The immune system responds
in a regulated fashion to microbes and eliminates them, but it
does not respond to self-antigens. Several regulatory mechanisms
function to 1) terminate responses to foreign antigens, returning
the immune system to a basal state after the antigen has been
cleared; and 2) maintain unresponsiveness or tolerance to self-
antigens. In this review, the emphasis of the authors is on T
lymphocytes, since many of the recent advances have come from
studies of T cells, but the authors propose it is likely that the
general principles are applicable to all lymphocytes. The authors
suggest that elucidating the nature of these homeostatic
mechanisms may lead to better strategies for suppressing harmful
immune responses, and for augmenting and sustaining beneficial
responses to microbial vaccines and tumors.
QY: Abul K. Abbas, Harvard Univ. Medical School 617-432-1550.
(Science 10 Apr 98 280:243) (Science-Week 1 May 98)


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

IN FOCUS: ON THE REALITY OF OBJECTS IN PHYSICS

"When we say that a thing is real we are simply expressing a sort
of respect. We mean that the thing must be taken seriously
because it can affect us in ways that are not entirely in our
control and because we cannot learn about it without making an
effort that goes beyond our own imagination. This much is true
for instance of the chair on which I sit (to take a favorite 
example of philosophers) and does not so much constitute evidence
that the chair is real but is rather just what we _mean_ when we
say that the chair is real. As a physicist I perceive scientific
explanations and laws as things that are what they are and cannot
be made up as I go along, so my relation to these laws is not so
different from my relation to my chair, and I therefore accord 
the laws of nature (to which our present laws are an
approximation) the honor of being real. This impression is
reinforced when it turns out that some law of nature is not what
we thought it was, an experience similar to finding that a chair
is not in place when one sits down. But I have to admit that my
willingness to grant the title of 'real' is a little like Lloyd
George's willingness to grant titles of nobility; it is a measure
of how little difference I think the title makes."

-- Steven Weinberg: _Dreams of a Final Theory_
   (Pantheon Books, New York 1992 p.46)


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