Maquina Lectora

Notes of a curious mind

Tag: History of science

Climate Histories: The Restless Sphere – IGY and the beginning of the race to space

…to observe geophysical phenomena and to secure data from all parts of the world; to conduct this effort on a coordinated basis by fields, and in space and time, so that results could be collated in a meaningful manner. [1]

In the early 1950s, the American physicist and engineer Lloyd Berkner started to investigate the development of the Earth’s atmosphere but the lack of available data limited his research. He felt that fundamental questions about global-scale environmental processes would remain unsolved unless opportunities are created to collect data on a worldwide basis.[2]

Berkner, a man of great energy, decided to create these opportunities. With several colleagues, he proposed, in 1950, an international geophysical programme modelled on the International Polar Years of 1882-1883 and 1932-1933.  He envisaged a large-scale global programme of intergovernmental cooperation in scientific research, that would allow scientists from around the world to take part in a series of coordinated observations of various geophysical phenomena.

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Why is the Sky Dark at Night? The Olbers’ Paradox, and Edgar Allan Poe’s Eureka

Why is the Sky Dark at Night? You might think that the answer is simple and obvious.  The sky appears dark because our side of Earth faces away from the Sun. But then, the universe is endless, it contains billion galaxies and innumerable luminous stars that we should be able to see their light from a particular distance away. Therefore, the night sky should be bright as noon!

The dark night sky paradox was a problem that dogged many astronomers since Kepler. But it was  the physician and astronomer Wilhelm Olbers, a man of amazing intellect, the first who tried to address the problem. He theorized that interstellar space is not transparent, but contains dust which absorbs energy from the stars, preventing some of their light from reaching us on Earth. The dark night sky problem was named after him the Olbers’ Paradox.

Curiously enough, it was the writer Edgar Allan Poe that first came up with at least part of the answer. Edgar Allan Poe, famous for his tales and poems of mystery, had a keen interest in science and in the field of cosmology, in particular. Just one year before his premature death in 1849, Poe wrote Eureka: An essay on the material and spiritual universe, a strange, intensive, and metaphysical, yet quite scientific in content, prose poem, which he dedicated to the  naturalist Alexander von Humboldt.

“I design to speak of the Physical, Metaphysical and Mathematical – of the Material and Spiritual Universe – of its Essence, its Origin, its Creation, its Present Condition and its Destiny.”

In Eureka, Poe claimed, among other things, that the universe is finite – in 1848 a finite-aged universe was mere speculation, and adopted a more philosophical phraseology of Newton’s Law of Gravitation, claiming that gravity is nothing but the attraction of every atom to the other atoms.

“Every atom, of every body, attracts every other atom, both of its own and of every other body, with a force which varies inversely as the squares of the distances between the attracting and attracted atom.”

Poe also pondered the question of the Olders’ Paradox. He suggested that the universe is not old enough to fill the sky with light. Is also endless in size; we see only a tiny part of it, and that observable part contains too few stars to fill up the sky with light. Poe knew that light moves extremely quickly but he claimed that there hasn’t been enough time for the light to reach us from farthest reaches of the universe.

“No astronomical fallacy is more untenable, and none has been more pertinaciously adhered to, than that of the absolute illimitation of the Universe of Stars. The reasons for limitation, as I have already assigned them, à priori, seem to me unanswerable; but, not to speak of these, observation assures us that there is, in numerous directions around us, certainly, if not in all, a positive limit—or, at the very least, affords us no basis whatever for thinking otherwise. Were the succession of stars endless, then the background of the sky would present us an uniform luminosity, like that displayed by the Galaxy—since there could be absolutely no point, in all that background, at which would not exist a star. The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all. That this may be so, who shall venture to deny? I maintain, simply, that we have not even the shadow of a reason for believing that it is so.”

In the 1920s American astronomer Edwin Hubble demonstrated the existence of other galaxies besides the Milky Way and that these galaxies are moving away from ours. What Hubble observed when he looked at the distant galaxies, was that their light was redshifted (stretched out to longer wavelengths), an effect became known as the Hubble expansion, and thus the galaxy clusters were moving away from each other.

The universe is now believed to be approximately 13.8 billion years old and current observations show that the bulk of material in space is non-luminous dark matter. Poe was right. But there is also another, additional, reason of why the sky is black. Stars, like our Sun, shine for a few billion years, before they consume their supply of fuel and collapse into a white dwarf. The collapse of the old stars provides material that will give birth to a new generation of stars. But this material is not enough to provide fuel that would keep the stars shining forever and fill up all the space with light. And so the night sky is dark.

 

References and further reading

Edgar A. Poe, Eureka: An essay on the material and spiritual universe

Soter, Steven, and Neil deGrasse Tyson. 2001. Cosmic horizons: astronomy at the cutting edge. New York: New Press.

Heinrich Olbers.” Astronomy & Space: From the Big Bang to the Big Crunch. Gale, 2008. Biography in Context. Web. 22 Apr. 2016, 2008. Biography in Context. Web. 22 Apr. 2016

Image credit: NASA/JPL-Caltech

 

The Callendar Effect by James Rodger Flemming

Guy Callendar was an English engineer, who in the 1930s estimated that man had added about 150,000 million tonnes of CO2 during the past century and the planet had undergone warming on the order of one degree Fahrenheit (0.5 degrees Celsius).

CallendarIn his first published paper, in February 1938, titled “The artificial Production of Carbon Dioxide and its Influence on Temperature”, Callendar showed that there is “a quantitative relation between the natural movement of this gas and the amounts produced by the combustion of fossil fuel”, and argued “that the activities of man could have any influence upon phenomena of so vast a scale… that is not only possible, but is actually occurring at the present time.”

He also referred to the oceans as a “giant regulator of carbon dioxide” which had exceeded the limits of the natural carbon cycle and would not be able to absorb all or most of its excess. But as Arrhenius before him, Callendar appealed the idea of atmospheric warming. Concluding his article he speculated that the combustion of fossil fuels “is likely to prove beneficial to mankind in several ways, besides the provision of heat and power…..  Small increases of mean temperature would be important at the northern margin of cultivation, and the growth of favourably situated plants is directly proportional to the carbon dioxide pressure. In any case the return of the deadly glaciers should be delayed indefinitely.”

Callendar published his discoveries in a series of papers, but they did not raise any interest from the scientific community. Only, later, in 1957, just before the beginning of the International Geophysical Year (IGY) – the first global scale experiment that recognised the potential of satellite technology in studying the Earth -, Hans Seuss and Roger Revelle, although they believed “that it was absolutely impossible to have had a sufficient increase in the CO2 amount in this century”, they referred to the “Callendar effect,” defining it as “climatic change brought about by anthropogenic increases in the concentration of atmospheric carbon dioxide, primarily through the processes of combustion.” Suggestive of Callendar’s brilliance was the fact that years later, scientists forecasted that some countries (Russia, Canada, New Zealand) will gain form climate change through an improved capacity for growing food, and used his prognosis that to promote and gain political support for their research projects to study climate change.

James Rodger Fleming is a professor at Colby College and a leading historian of atmospheric sciences and weather prediction. He has written a really fascinated book.

 

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