Is the amount of energy in the universe constant?
The first law of thermodynamics – the science of heat and energy that governs the behaviour of the universe – states that energy cannot be created or destroyed, only transferred from one form to another. So despite appearances, the amount of energy in the cosmos is constant. However, the cosmos is filled with strange forms of energy that we know very little about – just four per cent of the universe is locked up in the mass of visible matter, about 25 per cent is unknown dark matter and about 70 per cent is mysterious dark energy, which seems to be a kind of ‘negative gravity’ driving the expansion of the cosmos. Some physicists even think that normal and ‘negative’ forms of energy balance out so that the universe’s overall energy is not only constant, it’s zero.
WHEN WAS THE RIALTO BRIDGE IN VENICE BUILT?
The Rialto Bridge is one of only four bridges that span the Grand Canal in Venice, Italy. The stone bridge was commissioned in the late-16th century to replace the previous wooden structure, which was prone to collapse. Blueprints were submitted by the most eminent architects of Renaissance Italy, including Michelangelo, but the commission went to the relatively unknown Swiss-born Antonio da Ponte in 1588, whose design, featuring
