A mathematical discrepancy in the expansion rate of the Universe is now "pretty serious", and could point the way to a major discovery in physics, says a Nobel laureate.
The most recent results suggest the inconsistency is not going away.
Prof Adam Riess told BBC News that an unknown phenomenon, such as a new particle, might explain the deviation.
The difference is found when comparing precise measurements of the rate obtained in different ways.
However, the statistics are not yet at the threshold for claiming a discovery.
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