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Arcadia High School *
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Course
111
Subject
Astronomy
Date
Nov 24, 2024
Type
Pages
3
Uploaded by KidGazelle146
Wendy Freedman is well known for her work refining the Hubble constant. She was the Director of the Carnegie Observatories until 2015 when she
joined the faculty at the University of Chicago.
The Hubble measurement was so important that it has been re-examined by several astronomers,
including
Wendy Freedman
and her colleagues in 2001. Compare the range of distances and
recession velocities from
their work
, reproduced below, with the
original Hubble data
. The exact
value for the Hubble constant, H0, is still a topic of
active
research and intense debate.
[Figure 7]
Updated measurements to refine the Hubble Constant by Freedman and colleagues who used the aptly named Hubble Space Telescope in 2001. The
bottom plot shows the residuals - the scatter after fitting for the Hubble constant. Why is the scatter in the Hubble constant larger for the galaxies that
are closest to us? Shouldn't we have more precise data for the closest galaxies?
Question
What existed before the Big Bang? No one knows - maybe a quantum soup of energy. What
triggered a Big Bang where a matter-dominated universe emerged? No one knows. There is quite a
bit about our universe that we don't understand. But we do know that the universe is expanding. We
know that the background temperature of the universe is the same in all directions, supporting the
idea that all of the material in the universe was in thermal contact 14 Byr ago. And we know that
there were tiny deviations from that singular temperature that point to density variations that gave
rise to stars, galaxies, planets, and life.
The Early Universe
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