Jo Marchant: High in the mountains of northern Colorado, a 100-foot tall tower reaches up through the pinetops. Brightly coloured and strung with garlands, its ornate gold leaf glints in the sun. With a shape that symbolises a giant seated Buddha, this lofty stupa is intended to inspire those on the path to enlightenment.

Visitors here to the Shambhala Mountain Centre meditate in silence for up to 10 hours every day, emulating the lifestyle that monks have chosen for centuries in mountain refuges from India to Japan. But is it doing them any good? For two three-month retreats held in 2007, this haven for the eastern spiritual tradition opened its doors to western science. As attendees pondered the “four immeasurables” of …