By Jonathan Amos
Science reporter, BBC News
The next phase in physics' great 21st century quest - to detect gravitational waves - has been approved.
More than $200m (£100m) is to be spent upgrading the US Laser Interferometer Gravitational-wave Observatories.
Ligo is hunting for ripples predicted to be seen in the fabric of space-time when extreme cosmic events occur, such as the merger of super-dense stars.
Confirmation of the waves' existence should open up new ways to study the mysteries of the Universe.
Ultimately, scientists would hope to be able to probe these ripples for information about what happened just fractions of a second after the Big Bang itself.
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more:
http://news.bbc.co.uk/2/hi/science/nature/7348653.stm