Scientists say they believe they have captured the elusive Higgs Boson particle that gives matter mass.
Professor John Womersley, chief executive of the Science and Technology Facilities Council, told reporters at a London briefing that they had discovered a particle consistent with the Higgs Boson.
Discovery is the important word. That is confirmed. It's a momentous day for science.
There is a strong Welsh connection to the groundbreaking scientific project as Dr Lyn Evans from Aberdare was the project leader.
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A rather wet and windy evening, with rain in the north and showers elsewhere.
The 19-year-old's body was discovered in Builth Wells last month, just days after he was reported missing at the Royal Welsh Show.
The funeral has taken place of a one-year-old girl who died when a parked car rolled into a wall, which then collapsed on her.