| Measuring deceleration using supernovae |
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| � | Plot
of mv �vs.
z�� is really a plot of distance vs.
velocity |
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| � | If
faint (distant earlier)
objects show slightly higher z |
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| than
expected from extrapolation based on nearby (present day) objects, |
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| then
expansion rate was faster in the past and has been decelerating |
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| � | Surprise
results from 1998 indeed do suggest accelerating expansion |
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| � | May be due to �cosmological constant� proposed by Einstein |
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| � | AKA �Dark energy� or �Quintessence� |
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