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Optics in Physics, Part II

Spectroscopy is the study of the absorption and emission of light by atoms and molecules, and how this relates to the wavelengths of light. It is a science of the spectrum, a set of energy bands of varying wavelengths (colours) produced by electromagnetic radiation. It is typified for a visually oriented species like humans by the rainbow band of colours that emerges when you pass white light through a prism (or sunlight through raindrops). This property of light became the domain of Isaac Newton in the late 17th century. In his 1704 masterpiece of theoretical dualism, Opticks, Newton defined many of the ground rules 200 years before spectroscopy was first seriously applied.

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Optical Instruments, Part I

It’s amazing how progress in astronomy has followed in huge leaps upon the development of new observational technology. The Middle Eastern scholars of the first five hundred years AD gave us the basis for mapping the sky when they devised the concept of degrees of arc—the novel idea that cycles can be represented by circles, quantitatively divided up into equal segments we today call degrees. They also invented the astrolabe, an instrument for measuring celestial angles. This technology carried us through the revelations of Copernicus, the eye-watering accuracy of Tycho Brahe’s observational catalogues, and subsequent analysis by Johann Kepler which resulted in our understanding of orbital motion and which led ultimately to Newton’s laws of motion and gravitation.

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A Letter to a Reader of The Virtue of Heresy

The stars are what they are irrespective of the opinions expressed in the field of cosmology. It amazes me that pronouncements are made about distant objects with such unshakeable certainty when in the cold light of day the reach of verifiable science is not nearly so self-assured. I am reminded of Al Gore’s brazen assertion that “the science is settled” in climatology, a field which rivals cosmology in chaotic outcomes. The most daunting challenge facing space science is that of scale. In an infinite Universe, we will always be infinitely more ignorant than we are wise. In my view, we have more than enough to keep us occupied in the celestial neighbourhood, and would do well to take things one step at a time. Compare the science proposed in Hannes Alfven and Gustav Arrhenius “The Evolution of the Solar System” with Alan Guth’s pronouncements on Inflation Theory, or George Smoot’s take on the CMB, or indeed, even the core principles of General Relativity and Quantum Mechanics. The question I like to ask myself is “How does this theory connect to observed reality?” In a sitting room conversation with Halton Arp a few years ago, the late Fred Hoyle said, “I suppose that in the end, Chip, the Universe will have its say.”

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Ndaba | March 2009

Astronomy is the study of the greater environment, that part of the Universe that appears to us as the celestial sphere—the sky. By day, it is dominated by the Sun, our very own star, but by night it becomes a wonderland as the earth’s shadow dims the sunlight and allows us to see the Milky Way. With the naked eye we can see, depending on conditions, the Moon (the Earth’s only substantial natural satellite), 6 planets, part of the Milky Way galaxy, and our sister spiral galaxy, Andromeda M31. Of course, there are also transient phenomena that come and go from view relatively quickly, like artificial satellites, comets, and meteors. And Jumbo jets!

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