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Universe 'expanding like a rollercoaster'
The universe has expanded at vastly
different speeds through its history in a
pattern similar to the peaks and troughs of
a rollercoaster, scientists claim.
Over the last five billion years a mysterious
force known as dark energy has caused the
Universe to grow ever faster, gaining speed
as it continues to increase in size.
But a new study of an earlier period of
history has revealed that the younger
Universe was constrained by gravity and
expanded at a much slower rate.
About seven billion years ago its...
