Ai Weiwei unveils his epic new Australian work: ‘90% of art is just garbage. Real art questions the existing order’

<p>From his farm in Portugal, the acclaimed artist speaks about war, peace, the state of the world – and his 40 metre sculpture Mushrooms, on Sydney Harbour</p><p>“It’s like a film set. Like it’s not real,” the bemused Uber driver says as we pass through a succession of silent rura