A mysterious substance called dark energy is making our universe expand at a faster and faster rate, but scientists have problems understanding what it is.
They also struggle with the contradiction that a smaller than expected energy source is enough to move something so very big.
The complexities of cosmic physics were up for discussion last night in Dublin at the annual Hamilton Lecture. And who better to do the explaining than Nobel laureate Prof Steven Weinberg who predicted the size of the dark energy that is pushing out the edges of the universe. "This is not something we invented to explain the latest findings," Prof Weinberg told his capacity audience last night. "Knowing the state of the [ dark matter] is one of the most important ideas to arise over the last few decades," he said.
Also known as the energy of the vacuum of space, it is the motive force known to be driving the expansion of the universe. It is known as "dark" however because it is such a problem to understand, Prof Weinberg admits. "This has us in a pickle."
Organised by the Royal Irish Academy, The Irish Times and Depfa Bank plc, the Hamilton Lecture honours William Rowan Hamilton, one of Ireland's greatest scientists.