In the late 1990s
, observations of type I supernova
produced the unexpected result that the expansion of the universe
appears to be accelerating. These observations appear more firm as new data has appeared.
This means that the speed with which a distant galaxy
recedes from us increases over time.
If this trend continues, eventually we won't be able to see any other galaxies any more. This new theory of the end of the Universe has been called the Big Rip.
The two theoretical approaches to explain this are a non-zero cosmological constant, which may also have caused the period of inflation, or a form of matter known as quintessence.
The observation of an accelerating universe appears to present great problems for Dyson's eternal intelligence.
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