[Vision2020] "Physics Today" article "Copernicus and Arrhenius: Physics Then and Physics Today"

[Ted Moffett]

http://physicstoday.org/resource/1/phtoad/v64/i10/p39_s1?bypassSSO=1

Science controversies past and present

Steven Sherwoo

October 2011, page 39

Reactions to the science of global warming have followed a similar
course to those of other inconvenient truths from physics.

Science—especially the science behind climate change—is under fire.
The climate issue has sparked a vigorous, and at times surreal, public
debate that seems to pit experts against one another on even the most
basic facts, such as whether human greenhouse gas emissions dominate
natural ones, whether added carbon dioxide alters the planetary
emission of thermal radiation to space, and whether global
temperatures are rising.1 At its heart, global warming is a physics
problem, albeit a messy one that cannot proceed far without bringing
in meteorology, oceanography, and geology. (See the article by Raymond
Pierrehumbert in PHYSICS TODAY, January 2011, page 33 .) The climate
debate has spread far beyond the confines of any of those scientific
circles and into the media and public sphere, where politicization and
vitriol are legion.

Although nearly all experts accept that the greenhouse gases emitted
by humans have caused significant warming to the planet and will
likely cause much more, only about half the US public agrees, even
after years of heavy media coverage. How did we get into such a mess?
What are the implications for science, for how it should be
communicated, and for how debates should be interpreted? Some insights
may be gained by noting that global warming is not the first
“inconvenient truth” in physics. Consider this description of another,
bygone debate:
The decision [whether to accept the new theory] was not exclusively,
or even primarily, a matter for astronomers, and as the debate spread
from astronomical circles it became tumultuous in the extreme. To most
of those who were not concerned with the detailed study of celestial
motions, Copernicus’s innovation seemed absurd and impious. Even when
understood, the vaunted harmonies seemed no evidence at all. The
resulting clamor was widespread, vocal, and bitter.

Thus does science historian Thomas Kuhn describe the difficulties
experienced by astronomers in convincing the public of the
heliocentric theory of the solar system, which ultimately ushered in
the scientific revolution. The “clamor” prevailed around the time of
Galileo Galilei, more than a half century after Nicolaus Copernicus,
on his deathbed, published the heliocentric model in 1543.
Copernicus’s calculations surpassed all others in their ability to
describe the observed courses of the planets, and they were based on a
far simpler conception. Yet most people would not accept
heliocentricity until two centuries after his death.

Why did it take so long? To modern minds, the Ptolemaic model of the
solar system, with its nested cycles and epicycles, seems rather
silly. Surely, the need for a new tweak to the model each time more
accurate observations came along should have been a tip-off that
something fundamental was wrong. The heliocentric model’s elegance and
simplicity, on the other hand, are now appreciated as the hallmarks of
credibility for a scientific theory.

Paradigm shifts

It did take scientists a while, although not two centuries, to see the
heliocentric model’s merit. Astronomers quietly adopted Copernicus’s
calculations soon after they were published, but without at first
accepting the heliocentric premise on which they were based. As young,
open-minded astronomers replaced their elders, a paradigm shift toward
the modern view began. By the time of Johannes Kepler’s recognition of
simple elliptical orbits in 1609 (see the article by Owen Gingerich in
PHYSICS TODAY, September 2011, page 50 ) and Galileo’s observations
the following year, many top astronomers had converted to the
Copernican view.

The revelations from Galileo’s telescope (lunar craters, migrating
sunspots, planetary moons, and more), though spectacular, didn’t
directly validate the heliocentric model. Instead, their most
important effect was to challenge the preconceived notions that
prevented the model’s acceptance: that the heavens were perfect, that
all celestial objects orbited Earth, that Scripture fully described
the universe (exemplified by Dante Alighieri’s conception of a
geocentric divine arrangement, shown in figure 1).2 Once those errors
were revealed, the mind reopened to new possibilities. Modern
educators have recently realized that a similar process is important
in teaching physics in the classroom: Identifying and revealing
incorrect intuitions—based on, say, friction-dominated systems—is
sometimes necessary before students will truly assimilate an
understanding of more general validity, such as Newton’s laws of
motion. (See the article by Edward Redish and Richard Steinberg in
PHYSICS TODAY, January 1999, page 24 .)

More astute critics such as Tycho Brahe had a legitimate objection to
the Copernican theory: If Earth is moving, one should see evidence of
parallax in the shifting of the stars over the course of a terrestrial
orbit, and Tycho could find none. But stars in Galileo’s telescope
remained point-like even under strong magnification, which suggested
that they were very distant indeed, and that the parallax would
therefore be unobservably small; Galileo’s observations thereby
removed Tycho’s objection. (Parallax was eventually observed in 1838.)

Despite the power of the new theory and its observational successes,
many people, even in the scientific community, could not relinquish
the idea that the universe was built around them. Their belief was so
strong that some scientists simply refused to look through Galileo’s
telescope, and others invented ridiculous explanations for what it
showed.2 Compromise models became popular; Tycho himself proposed that
the planets orbit the Sun but maintained that the Sun and its
entourage all orbit Earth. Over time such crutches fell by the
wayside; Copernicus’s view was generally accepted among scientists by
the late 17th century and among the public by the late 18th century.

The progression of the global warming idea so far has been quite
similar to that of Copernicanism. The idea that changes in atmospheric
greenhouse gas concentrations can and do cause significant climate
changes (a notion for which I will use the shorthand term “greenhouse
warming”) was proposed qualitatively in 1864 by renowned physicist
John Tyndall, when he discovered carbon dioxide’s opacity to IR
radiation. In 1896 Nobel laureate Svante Arrhenius quantitatively
predicted the warming to be caused in the future by coal burning; the
prediction was tested and promoted by steam engineer Guy Callendar in
the late 1930s. At first few could accept that humans were capable of
influencing the climate of an entire planet, but over time, and with
more calculations, scientists found the possibility increasingly
difficult to dismiss.

As with Copernicanism, astute observers found legitimate objections.
The 15-micron absorption of atmospheric CO2 was already largely
saturated, which some argued would prevent additional CO2 from having
any effect. The ocean, with its large carbon-storing capacity, seemed
poised to soak up most of the human emissions. By the 1970s, however,
those objections had deflated in the face of contrary evidence,3 and a
growing number of papers on climate were noting the likelihood of
future warming.

Many who are unwilling to accept the full brunt of greenhouse warming
have embraced a more comforting compromise reminiscent of the Tychonic
system: that CO2 has some role in climate but its importance is being
exaggerated. But accepting a nonzero warming effect puts one on a
slippery slope: Once acknowledged, the effect must be quantified, and
every legitimate method for doing so yields a significant magnitude.
As the evidence sinks in, we can expect a continued, if slow, drift to
full acceptance. It took both Copernicanism and greenhouse warming
roughly a century to go from initial proposal to broad acceptance by
the relevant scientific communities. It remains to be seen how long it
will take greenhouse warming to achieve a clear public consensus; one
hopes it will not take another century.

Backlash and politicization

Inconvenient scientific claims also show parallels in their political
progression. In the decades before Galileo began his fervent promotion
of Copernicanism, the Catholic Church took an admirably philosophical
view of the idea. As late as 1615, Cardinal Robert Bellarmine
acknowledged that “we should . . . rather admit that we did not
understand [Scripture] than declare an opinion to be false which is
proved to be true.” But the very next year he officially declared
Copernicanism to be false, stating that there was no evidence to
support it, despite Galileo’s observations and Kepler’s calculations.2
Institutional imperatives had forced a full rejection of
Copernicanism, which had become threatening precisely because of the
mounting evidence.

Even Albert Einstein was not immune to political backlash. His theory
of general relativity, excerpted on the notebook page in figure 2,
undermined our most fundamental notions of absolute space and time, a
revolution that Max Planck avowed “can only be compared with that
brought about by the introduction of the Copernican world system.”5
Though the theory predicted the anomalous perihelion shift of
Mercury’s orbit, it was still regarded as provisional in the years
following its publication in 1916.

When observation, by Arthur Eddington and others, of a rare solar
eclipse in 1919 confirmed the bending of light, it was widely hailed
and turned Einstein into a celebrity. Elated, he was finally satisfied
that his theory was verified. But the following year he wrote to his
mathematician collaborator Marcel Grossmann:

This world is a strange madhouse. Currently, every coachman and every
waiter is debating whether relativity theory is correct. Belief in
this matter depends on political party affiliation.

Instead of quelling the debate, the confirmation of the theory and
acclaim for its author had sparked an organized opposition dedicated
to discrediting both theory and author. Part of the backlash came from
a minority of scientists who apparently either felt sidelined or could
not understand the theory. The driving force was probably professional
jealousy,6but scientific opposition was greatly amplified by the
anti-Semitism of the interwar period and was exploited by political
and culture warriors. The same forces, together with status quo
economic interests, have amplified the views of climate contrarians.

The historical backlashes shed some light on a paradox of the current
climate debate: As evidence continues to accumulate confirming
longstanding warming predictions and showing how sensitive climate has
been throughout Earth’s history, why does climate skepticism seem to
be growing rather than shrinking? All three provocative
ideas—heliocentricity, relativity, and greenhouse warming—have been,
in Kuhn’s words, “destructive of an entire fabric of thought,” and
have shattered notions that make us feel safe.2 That kind of change
can turn people away from reason and toward emotion, especially when
the ideas are pressed on them with great force.

The agitations of modern greenhouse proponents appear to have provoked
an antiscience backlash similar to the one against Galileo. In the
space of only two years, almost as fast as Bellarmine changed his
position on Copernicanism, leading moderates have been squeezed out of
the main conservative political parties in both the US and Australia
and replaced by hard-line rejecters of climate science. In Australia,
climate policy was the leading issue behind the backlash; in the US it
was one of many contributing factors. Because the Catholic Church of
Galileo’s day had generally been a supporter of science and open
inquiry, the condemnation of Copernicanism as it grew scientifically
solid shocked many devout Catholics.2 Likewise, modern conservative
political parties have until recently been friends of science,
including climate and environmental studies. In the 1970s Republicans
and Democrats in Congress were equally concerned about climate change,
and as recently as 2004 leading Republicans were—at least in
public—enthusiastic in their support of science. Their recent
rejections of climate science have probably shocked many supporters.
In both cases the backlash seems to have come when leaders were pushed
to act on the basis of new evidence. (Figure 3 further illustrates the
connection between economic incentives and rejection of climate
science.)

The ugly nature of the current climate debate, with its increasingly
frequent characterization of scientists as opportunists,
totalitarians, or downright criminals, is also, unfortunately, not
new. Copernicus (posthumously) and his prominent followers through
Isaac Newton were all accused of being heretics or atheists. Einstein
was derided by his political opponents through the 1920s and 1930s as
a Communist—despite his dim view of the Soviet Union—or simply as a
fraud. When a group of American women tried to prevent him from
entering the US because of his supposed Communism, he quipped, “Never
before have I experienced from the fair sex such energetic rejection
of all advances, or if I have, then certainly never from so many at
once.”9 At one point Einstein stopped giving public lectures out of
fear for his personal safety, also now a worry for some greenhouse
warming proponents.

Bogus debates

It was easy for those not wishing to accept Copernicus’s insight to
devise persuasive counterarguments against it. For example, in 1597
one prominent commentator declared that a moving Earth would “see
cities and fortresses, towns and mountains thrown down,” and that
“neither an arrow shot straight up, nor a stone dropped . . . would
fall perpendicularly.”2 Those arguments would not fly today because
nearly everyone has experiential knowledge, from riding in cars and
airplanes, of what are now called the Galilean principles of
invariance. But laypeople in the 17th century did not. To explain
those abstractions to them would have been much more difficult than to
make the neat, simple, and wrong argument advanced by naysayers. As
the 17th century progressed, arguments against heliocentricity tended
to veer more toward scriptural rather than scientific ones, but both
types persisted.

Greenhouse warming today faces an even greater array of bogus
counterarguments based on the uninformed interpretation of data from
ice cores, erroneous views about natural carbon sources, alleged but
unobserved alternative drivers of climate change, naive expectations
of the time scales over which models and observations should match,
and various forms of statistical chicanery and logical fallacy. Many
of the arguments sound reasonable to an inexpert but intelligent
layperson. Critics use the alleged flaws to attempt to discredit the
entire field.

Debates between mainstream scientists and silver-tongued opponents
cannot be won by the side of truth no matter how obvious the fallacies
may be to an expert. Incredibly, as recently as the mid-19th century,
a highly charismatic figure calling himself “Parallax” devoted two
decades of his life to crisscrossing England arguing that Earth was
flat. He debated legitimate astronomers—sometimes teams of them—in
town-hall-type settings and wowed audiences.10 For similar reasons,
Einstein himself gave up debating his critics early in the 1920s.

Nearly a century after Callendar began to win converts to the idea,
among experts actively studying and publishing peer-reviewed articles
about the climate system the portion who accept greenhouse warming is
now more than 95%;11,12 among the broader scientific community, a
slightly smaller majority;11 and among the public at large in the US
and Australia, who mostly receive news on climate filtered through a
media that highlights contrarian views and controversy, only about
half,13 although the exact number depends on the survey details. A
similar situation prevailed for Copernicanism in the mid 17th century:
Nearly all important astronomers had become Copernicans by then, but
not the public, whose perception was through poets and other
popularizers (such as Jean Bodin and John Donne, shown in figure 1)
who continued to be skeptical or derisive. It would require the rest
of the 17th century and most of the 18th to convert the public to
Copernicanism.

Deduction, empiricism, and prediction

A weakness that impeded the acceptance of all three inconvenient
ideas, especially outside expert circles, was the absence of a smoking
gun or a benchtop experiment that could prove any of them
unambiguously. Instead, heliocentricity and relativity succeeded by
explaining the existing observations with fewer ad hoc assumptions. To
judge them, one had first to consider the plausibility of the theory
and then to appreciate how unlikely it would be for observations to
have obeyed it by accident. That reasoning process is often
unintuitive and requires detailed knowledge.

Like the Copernican model, Einstein’s theory of general relativity was
a fundamental conceptual simplification arising from a few brilliant
insights and an ability to question conventional wisdom. Einstein
asked if there might be a way to represent the universe such that
gravitational and inertial mass, which are distinct but coincidentally
equal in Newtonian physics, were a single property. That constraint
plus the insistence that the theory would apply in any arbitrary
spacetime coordinate system were, with clever reasoning and some
daunting math, sufficient to uniquely specify the complete theory.

The current theory of global climate change is hardly elegant or
scientifically revolutionary, and in that respect it seems like no
bedfellow to the others. Its prominence comes from its implications
for the sustainability of current Western consumption patterns, not
from reshaping physics; its many contributors would not claim to be
Einsteins. What it shares with the others, however, is its origin in
the worked-out consequences of evident physical principles rather than
direct observation. That sort of bottom-up deduction is valued by
physics perhaps more than by any other science.

Indeed, the leaders of climate science in recent decades have largely
been trained as physicists.3 Global warming is the first environmental
forecast based on physical reasoning—the greenhouse effect and its
intensification as IR atmospheric opacity increases—rather than on
extrapolating observed patterns of past behavior. Anthropogenic
warming was not unambiguously detected until nearly the end of the
20th century, well after most experts knew it was coming.
Interestingly, forecast meteorologists, despite their familiarity with
weather and the atmosphere, are at least as skeptical of global
warming as the general public; so, to some extent, are
geologists.11,15 A similar situation confronted general relativity,
whose critics were mainly experimentalists and astronomical observers.
Traditional meteorologists and geologists both emphasize empiricism
and classification; they relish the complexity of natural phenomena
and typically consider ab initio theoretical approaches to be
hopeless. Physicists, however, prefer the opposite approach of
avoiding overly complex problems and seeking to strip the more
tractable ones to their barest essence. Such approaches often become
more powerful as technology advances.

A common refrain is the disparagement of new paradigms as mere
theories with too little observational basis. Parallax, the flat-Earth
proponent, beguiled audiences by deriding the “theory” of a globe
Earth, in contrast to the flat disk supposedly proven by observation.
Einstein’s colleague John Synge noted that relativists were easily
dismissed as people “splitting hairs in an ivory tower” who are “not
consulted in the building of a tower, a bridge, a ship, or an
aeroplane.” Critics emphasized the meager size of the then-observable
relativistic effects while brushing aside the theory’s deeper
implications.16 Nowadays, greenhouse proponents are also dismissed by
skeptics as out-of-touch academics infatuated with their models and
ignorant of data—as if science could be done with only one or the
other. Contrary to those myths, however, Einstein eagerly sought
observational tests of his theory from the beginning, and climate
models, imperfect though they are, are constantly tested for their
ability to reproduce many kinds of observed climate variations.

Lessons for scientists today?

Relativity contrarians basked in conspiracy ideas, claimed to be able
to disprove Einstein’s theory, and were convinced that the scientific
establishment was suppressing their alternative views6—all claims
echoed nowadays by climate contrarians. But it is not hard to spot the
differences between those groups and the real vanguard of a scientific
revolution. Copernicus, Einstein, Charles Darwin, and Alfred Wegener,
the founder of plate tectonics, all proposed powerful new theories
that challenged core assumptions held by humanity for generations.
Their theories steadily gained traction first among up-and-coming
experts, then among the general population. Relativity and climate
contrarians instead offer a wide range of mutually exclusive and
sketchy proposals, which generally predate the new theory and lack
predictive power. But because the contrarian proposals reinforce
traditional beliefs, they enjoy a prolonged period of public
popularity even as their currency among successive generations of
experts approaches zero.

It is jarring to ponder the scene of a colleague from the 17th century
refusing to look into a telescope—a level of aversion to inconvenient
facts, admittedly not common, that seems incredible. Yet modern
counterparts can perhaps be found in those who vilify the
Intergovernmental Panel on Climate Change without apparently ever
having examined its reports, or who repeat claims—such as global
warming having stopped in 1998—that can be trivially falsified by
looking at the data. A lesser form of denial can be found in the eager
adoption of Copernicus’s calculations by those rejecting his premises;
a modern parallel is the use of global atmosphere model simulations by
weather forecasters who reject the climatic implications of the
physical relationships on which the models are based. (The UK Met
Office, whose model development effort is probably the largest in the
world, now uses essentially identical atmosphere models for weather
and climate prediction.)

Despite the clear historical precedents, summarized in the timeline in
figure 4, scientists and environmentalists alike appear to have been
unprepared for the antiscience backlash now under way. A first step
toward better public communication of science, and the reason we need
it, may lie in recognizing why the backlash happens: the frailty of
human reason and supremacy of emotional concerns that we humans all
share but do not always acknowledge. That step could be as important
in the classroom as when engaging the public and policymakers more
widely. Tempering confidence with a dose of humility never hurts
either, as best articulated by Einstein himself: “All our science,
measured against reality, is primitive and childlike—and yet it is the
most precious thing we have.” (For more on public communication of
climate science, see the article by Richard Somerville and Susan Joy
Hassol on page 48 of this issue.)

Sadly, some new textbooks in climate and atmospheric physics are being
written with long prefaces explaining why students should believe what
the textbook says, despite contrary information from their parents,
radio talk show hosts, or the internet. Normally a textbook does not
have to defend itself. Since modern science, and physics especially,
is done primarily at the pleasure of the taxpaying public, such
developments should concern all scientists.

At the same time, history tells us that in the end, science will
probably come out fine. Whether the planet will is another matter.

Steve Sherwood is a codirector of the Climate Change Research Centre
at the University of New South Wales in Sydney, Australia.
References

See, for example, the FAQs from Climate Scientists Australia,
http://climatescientistsaustralia.org.au/science/faqs.html.
T. S. Kuhn, The Copernican Revolution: Planetary Astronomy in the
Development of Western Thought Harvard U. Press, Cambridge, MA (1957),
chap. 6.
S. Weart, The Discovery of Global Warming Harvard U. Press, Cambridge,
MA (2003).
T. C. Peterson, W. M. Connolley, J. Fleck, Bull. Amer. Meteorol. Soc.
89, 1325 (2008).
J. Eisenstaedt, The Curious History of Relativity: How Einstein's
Theory of Gravity Was Lost and Found Again A. Sangalli, trans.,
Princeton U. Press, Princeton, NJ (2006).
J. van Dongen, Stud. Hist. Philos. Mod. Phys. 41, 78 (2010).
N. Oreskes, E. M. Conway, Merchants of Doubt: How a Handful of
Scientists Obscured the Truth on Issues from Tobacco Smoke to Global
Warming Bloomsbury Press, New York (2010).
Z. Kunda, Psych. Bull. 108, 480 (1990). [MEDLINE]
B. Hoffmann, in collaboration with H. Dukas, Albert Einstein, Creator
and Rebel Viking Press, New York (1972), p. 164.
C. Garwood, Flat Earth: The History of an Infamous Idea Thomas Dunne,
New York (2008).
P. T. Doran, M. K. Zimmerman, Eos Trans. Am. Geophys. Union 90, 22 (2009).
W. R. L. Anderegg et al., Proc. Natl. Acad. Sci. USA 107, 12107 (2010).
J. M. Jones, “In U.S., Concerns About Global Warming Stable at Lower
Levels” (14 March 2011),
http://www.gallup.com/poll/146606/Concerns-Global-Warming-Stable-Lower-Levels.aspx
.
B. Hoffmann, in collaboration with H. Dukas Albert Einstein, Creator
and Rebel Viking Press New York (1972), p. 124.
E. Maibach, K. Wilson, J. Witte, A National Survey of Television
Meteorologists about Climate Change: Preliminary FindingsGeorge Mason
University, Fairfax, VA (2010).
J. Eisenstaedt The Curious History of Relativity: How Einstein's
Theory of Gravity Was Lost and Found Afain A. Sangalli, trans.,
Princeton U. Press, Princeton, NJ (2006).
BBC World Service survey on climate change attitudes, Sept. 2007,
http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/25_09_07climatepoll.pdf.
Coal data from the United Nations Energy Statistics Database, obtained
through http://nationmaster.com on 17 June 2011.
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Vision2020 Post: Ted Moffett
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