PhysicsDIY device to define the kilogram – using Lego Just in time for Christmas, instructions for a Lego watt balance, which can fix the official value of the kilogram, have been published ¿ìè¶ÌÊÓÆµ
SpaceThe piste at the end of the universe Weary of Whistler? Find Davos dull? For a vacation with a difference, blast off with our winter sports guide to the best off-earthly snow and ice Features