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Look
“into the past” to see if expansion rate was faster in
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early
history.
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To “look into the past” look very far away:
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Find “Ho” for very
distant objects, compare that to “Ho” for
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closer objects
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Remember – we found Ho by
plotting velocity (vr) vs.
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distance
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We found velocity vr from the red shift
(z)
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We found distance by measuring apparent magnitude (mv)
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of known brightness objects
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We can test for changing Ho by measuring
mv vs. z
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