 |
| Galileo Galilee |
‘Measure
what is measurable, and make measurable what is not so.’ - Galileo Galilee
Science is measuring.
Of course, it is about much more than measuring. The scientific approach includes deduction,
induction, lateral thinking and all of the other creative and logistical
mechanisms by which we arrive at ideas.
But what distinguishes the ideas of science from those of religion, philosophy
or art is that they are expressed as testable hypotheses – and by testable
hypotheses, scientists mean ideas that can be examined by observations or
experiments that yield outcomes that can be
measured.
Earth scientists use astonishingly diverse
approaches to measure our world, from the submolecular to the planetary, from
bacterial syntrophic interactions to the movement of continental plates. A
particularly important aspect of observing the Earth system involves chemical
reactions – the underlying processes that form rocks, fill the oceans and
sustain life. The Goldschmidt Conference, held this year in Florence, is the annual
highlight of innovations in geochemical methodologies and the new knowledge emerging
from them.
Geochemists reported advances in measuring the
movement of electrons across nanowires, laid down by bacteria in soil like electricians
lay down cables; the transitory release of toxic metals by microorganisms,
daily emissions of methane from bogs, and annual emissions of carbon dioxide
from the whole of the Earth; the history of life on Earth as recorded by the
isotopes of rare metals archived in marine sediments; the chemical signatures
in meteorites and the wavelengths of light emitted from distant solar nebulae,
both helping us infer the building blocks from which our own planet was formed.
******
The Goldschmidt Conference is often held in cities
with profound cultural legacies, like that of Florence. And although Florence’s legacy that is perhaps
dominated by Michelangelo and Botticelli, Tuscany was also home to Galileo Galilee,
and he and the Scientific Revolution are similarly linked to the Renaissance
and Florence. Wandering through the Galileo Museum is a stunning reminder of how challenging
it is to measure the world around us, how casually we take for granted many of
these measurements and the ingenuity of those who first cracked the challenges
of quantifying time or temperature or pressure.
And it is also exhilarating to imagine the thrill
of those scientists as they developed new tools and turned them to the stars
above us or the Earth beneath us.
Galileo’s own words tell us how
he felt when he pointed his telescope at Jupiter and discovered the satellites
orbiting around it; and how those observations unlocked other insights and
emboldened new hypotheses:
‘But what exceeds all wonders, I have discovered
four new planets and observed their proper and particular motions, different
among themselves and from the motions of all the other stars; and these new
planets move about [Jupiter] like Venus and Mercury... move about the sun.’
The discoveries of the 21st century are
no less exciting, if perhaps somewhat more nuanced.
******
 |
| Laura Robinson |
The University of Bristol is one of the world
leaders in the field of geochemistry. Laura Robinson co-chaired several sessions, while also
presenting a new approach to estimating water discharge from rivers, based on
the ratio of uranium isotopes in coral; the technique has great potential for
studying flood and drought events over the past 100,000 years, helping us to
better understand, for example, the behaviour of monsoon systems on which the
lives of nearly one billion people depend.
Heather Buss chaired a session and presented research
quantifying the nature and consequences of reactions occurring at the
bedrock-soil interface – and by extension, the processes by which rock becomes
soil and nutrients are liberated, utilised by plants or flushed to the oceans. Kate
Hendry, arriving at the University of Bristol in October, presented her latest
work employing the distribution of zinc in sponges (trapped in their opal hard
parts) to examine how organic matter is formed in surface oceans, then
transported to the deep ocean and ultimately buried in sediments; this is a key
aspect to understanding how carbon dioxide is ultimately removed from the
atmosphere. The Conference is not
entirely about measuring these processes – it is also about how those measurements
are interpreted. This is exemplified by Andy Ridgwell who presented two keynote lectures on his
integrated physical, chemical and biological model, with which he evaluated the
evidence for how and when oceans become more acidic or devoid of oxygen.
What next?
Every few years, a major innovation opens up new insights. Until about 20 years ago, organic carbon
isotope measurements (carbon occurs as two stable isotopes – ~99% as the
isotope with 12 nuclear particles and ~1% as the isotope with 13) were
conducted almost exclusively on whole rock samples. These values were useful in
studying ancient life and the global carbon cycle, but somewhat limited because
the organic matter in a rock derives from numerous organisms including plants,
algae and bacteria. But in the late 1980s, new methods allowed us to measure
carbon isotope values on individual
compounds within those rocks, including compounds derived from specific
biological sources. Now, John Eiler and
his team at Caltech are developing methods for measuring the values in specific
parts or even at a single position in
those individual compounds within those rocks.
This isotope mapping of molecules could open up new avenues for
determining the temperatures at which ancient animals grew or elide what
microorganisms are doing deep in the Earth’s subsurface.
Scientists are going to continue to measure the
world around us. And while that might
sound cold and calculating, it is not!
We do this out of our fascination and wonder for nature and our planet. Just like Galileo’s discovery of Jovian
satellites excited our imagination of the cosmos, these new tools are helping
us unravel the astonishingly beautiful interactions between our world and the
life upon it.
 |
| Prof Rich Pancost |