13 Journeys Through Space and Time by Colin Stuart

Author:Colin Stuart [Stuart, Colin]
Language: eng
Format: epub
ISBN: 9781782436881
Publisher: Michael O'Mara Books

Sagan below a picture of Charles Darwin and in front of a replica of Stanley Miller’s experiment on the origins of life

But what exactly sparked that first organism into life? To explore this idea further Sagan recreates a very famous experiment conducted by Stanley Miller in which the chemicals present on the early Earth are mixed and given a shot of electricity to simulate lightning. The result is a dark sludge of complex organic molecules – the building blocks of life. He then excitedly tells the captivated audience that material of a similar colour has been observed ‘in the vicinity of Jupiter’ and that the Voyager probes will be able to tell us more. ‘It may be that we can learn about the early chemistry of life best by examining the outer solar system,’ he says. ‘Perhaps, even, there is life out there. What is guaranteed is that those worlds are entrancing, fascinating and well worth a deep analysis. In only a few years we will have made such a deep analysis.’ (As it happened, the Voyager probes did not find any evidence of life on the gas giants.)

If not in the outer solar system, perhaps Mars is a better place to look for life. Sagan describes it as ‘a planet rich in legends and fable and tradition’, so we need to be careful, he says, as he begins his next Lecture. We should learn a lesson from Venus, the surface of which is blocked from our view by superheated carbon dioxide clouds crushing down with a surface pressure ninety times that on Earth. ‘If you want to know where hell is, it’s the surface of Venus,’ he says.

Before the Soviets landed probes on Venus, there was much speculation about what the Venusian surface might reveal, from swamps to deserts, oil fields to oceans of carbonated water, none of which were borne out. We’d been projecting our emotions on to the planet without solid evidence, Sagan warns. ‘These warnings are important when we start to study Mars because Mars has also been thought to be a place in many respects like the Earth, that we have placed our hopes and fantasies, wishes and desires on, and we must be cautious that our wishes do not blind us to the reality of a planet.’

He recalls the apparition of Martian canals mentioned by many previous Christmas Lecturers, concluding that the dubious canals ‘are an indication of the inaccuracy of the human hand, eye, brain combination. We are not perfect observers.’ All the more reason to explore the planet up close, and so by his fourth Lecture he has moved on to what we learned from NASA’s Mariner probes, several of which flew past Mars between 1965 and 1972. A key tool in understanding the spectacular pictures we’re about to see is crater counting. Donning a white lab coat, he calls for volunteers ‘who will enjoy making a mess of the Royal Institution’. His willing participants throw marbles into a box packed tightly with clay, creating near perfect craters many times bigger than the marbles themselves.

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