Quest 8(1)

Page 30

NASA’s Hubble Space Telescope snapped this image of the planetary nebula catalogued as NGC 6302, but more popularly called the Bug Nebula or the Butterfly Nebula.

In the darkest deepest recesses of our universe lurk extremely massive compact objects. Marisa Geyer and Jeandrew Brink explore the nature of spacetime around these exotic structures by observing objects in orbit around them.

Of butterflies and bumpy black holes


received an unusual gift. I found a box tied with a red ribbon waiting on my desk. Interesting – it wasn’t my birthday. I dropped my bags and opened the box uncovering two pink cheeked apples attached at the stem. It turns out that these apples are directly related to the first object whose carefully studied trajectory led to the formulation of the concept of gravitation.

An extract from William Stukeley’s manuscript which would later become the biography Memoirs of Sir Isaac Newton’s life. Image:The Royal Society

The two Newtonian apples gifted to me by my roommate, Cato Bekker. Image: Jane Geyer

28 Quest 8(1) 2012

From Newton to Einstein Legend has it that Sir Isaac Newton was sitting under an apple tree, when ‘boink’ an apple hit his head. The impact jolted him into the realisation that the same force that brought the apple crashing onto his head also keeps the moon falling towards the Earth and the Earth towards the Sun: gravity. The legend isn’t too far from the documented truth. In the manuscripts of William Stukeley, an archaeologist and one of Newton’s first biographers, he records a conversation that took place with Newton in 1726: ‘After dinner, the weather being warm, we went into the garden and drank thea, under the shade of some

apple trees...he told me, he was just in the same situation, as when formerly, the notion of gravitation came into his mind. It was occasion’d by the fall of an apple, as he sat in contemplative mood. Why should that apple always descend perpendicularly to the ground, thought he to himself.’ So important was this notion of gravity that in commemoration of its discovery, people have carefully cultivated the descendants of the original apple tree. It turns out that my roommate’s dad has a certified Newtonian apple tree on their farm in Franschhoek. When the tree bore its first two apples it made a perfect gift for her physics enthusiast friend. Since that first Newtonian apple fell, our understanding of gravity has been continuously refined. Newtonian gravity successfully predicts the elliptical motion of most of the solar system planets and for the most part suffices to help NASA put satellites and shuttles up in space. Newtonian gravity, however, cannot account for the way in which the planet Mercury orbits the Sun, or the fact that the Sun deflects the light from distant stars that pass it during an eclipse. Describing

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