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The Edge of Physics by Anil Ananthaswamy

The Edge of Physics by Anil Ananthaswamy

Author:Anil Ananthaswamy
Language: ru
Format: mobi, epub
Publisher: Houghton Mifflin Harcourt
Published: 2012-06-09T07:16:24+00:00


Out in the Karoo, Adrian finally got his wish for home-cooked Karoo lamb in a B&B in the Northern Cape town of Carnarvon, where we stayed for a night. We left Carnarvon early the next morning, soon turning off the paved road onto a by-now-familiar gravel road. We were nearly eight hours from Cape Town. The site for the Meer-KAT and the SKA was still about two hours deeper into the Karoo. As we drove, the shrubs got smaller and the landscape drier. Occasional splotches of bright pink and white flowers shocked with their incongruity. At times, dense fields of blackened boulders dominated the landscape on either side of the road. They looked as if they had been charred in a fire, but they were in fact chunks of dolerite, weathered to a dark sheen by wind and sun. We also passed massive piles of rocks that seemed to have been laboriously stacked on top of one another. Sometime during the Jurassic period, when dinosaurs roamed the land, vast outpourings of basalt covered the countryside. The basalt eroded, exposing dolerite, which is basalt that cooled and solidified well below the Earth's surface. As the dolerite cooled, cracks formed in the rocks, mostly at right angles. Eventually rainwater flowed along these cracks, eating away at them. The once sharp edges gave way to rounded contours. Today, they look like sacks of wool, hence the term "woolsack weathering" for this geological process.

Adrian braked to show me another odd sight—a nest of weaver-birds on an old telephone pole. In a land devoid of trees, the weaver-birds colonize any freestanding structure. In the Karoo, these happen to be abandoned telephone and electricity poles, and now and then the stump of a former windmill. The nests looked like lumps of dry grass that someone had tossed on top of these poles, but they were carefully constructed, designed to protect the eggs and the young from the weather and birds of prey—at least one of which was circling the nest as we watched.

The abandoned utility poles got us talking about the power requirements for the Square Kilometre Array. The SKA will need hundreds of megawatts of electricity, but bringing this power to the core site is going to be tricky. The best way to transmit huge amounts of power is to use high-voltage lines, but these are undesirable around a radio telescope. High voltage can ionize the surrounding air, causing what's called a corona discharge, which generates radio frequency interference (RFI) strong enough to mess up the faint signals from the cosmos. Even low-voltage power lines can spark, another source of RFI. The solution is to bring power on high-voltage lines to within about 45 kilometers of the core site and then step down the voltage and transmit the power using multiple cables strung on steel towers, finally burying them underground within 6 kilometers of the site. Weaverbirds will have to stick to their old broken poles for nesting.

We turned off onto yet another gravel road. Within minutes, I could sense that we were heading into special territory.



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