Asked by: Clare Johnson, West Yorkshire
To dig from London to Sydney, you would actually need to angle about 15° off the vertical, in a roughly easterly direction, so technically you are never digging straight down. Your tunnel would reach its closest point to Earth’s centre after about 6,150km and would slope upwards after that. Assuming, of course, that we ignore all the physical impossibilities inherent in such a project.
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Authors
Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.
![Image by Rakot13 (Own work) [CC BY-SA 3.0], via Wikimedia Commons](https://images.immediate.co.uk/production/volatile/sites/4/2018/08/Сама_скважиназаварена_август_2012-fec7567.jpg?quality=90&resize=620%2C413 "Image by Rakot13 (Own work) [CC BY-SA 3.0], via Wikimedia Commons")
