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What is the assumption that must be true for the Hubble time to be the correct age of the universe?
The Hubble time is the right age for the universe only if the expansion rate has been constant throughout the time since the expansion of the universe began.
Why was Hubble’s estimate about the age of the universe wrong?
This age estimate for the universe, Hubble acknowledged, was clearly less than the age of the Earth, as determined by geologists who measured the radioactivity in rocks. Walter Baade made the crucial observation that doubled the distance scale and thus resolved the problem that the universe seemed too young.
How was Edwin Hubble wrong?
Hubble’s values for his distances in 1929 were, however, wrong, by a large factor of ∼7! This was mainly due to a wrong zero-point calibration of the standard candles used at the time. All distances were thus too small by a factor of 7, and the expansion rate Ho too large by the same factor.
Why does the universe continue to expand?
If the gravity within the universe is strong enough, it could reign in the expansion and cause the universe to contract. If not, the universe will continue to expand forever. If omega (Ω) is greater than 1, then the universe will be closed. If it’s less than 1, the universe will be open.
How did Hubble prove the universe was expanding?
Hubble’s brilliant observation was that the red shift of galaxies was directly proportional to the distance of the galaxy from earth. That meant that things farther away from Earth were moving away faster. In other words, the universe must be expanding. He announced his finding in 1929.
How does Hubble’s Law tell us the universe is expanding?
During the 1920’s and 30’s, Edwin Hubble discovered that the Universe is expanding, with galaxies moving away from each other at a velocity given by an expression known as Hubble’s Law: v = H*r. So essentially, the Hubble constant sets the rate at which the Universe is expanding.
Can We tell the age of the universe without a cosmological constant?
If the astronomers who have measured the smaller values of the Hubble constant are correct, and if the smaller estimates of globular cluster ages are also correct, then all is well for the Big Bang theory, even without a cosmological constant. Measurements by the WMAP satellite can help determine the age of the universe.
How do we measure the age of the universe?
An alternative approach to estimating is the age of the universe is to measure the “Hubble constant”. The Hubble constant is a measure of the current expansion rate of the universe. Cosmologists use this measurement to extrapolate back to the Big Bang.
Is the universe’s expansion slowing?
Until recently, cosmologists (the scientists who study the universe) assumed that the rate of the universe’s expansion was slowing because of the effects of gravity. However, current research indicates that the universe may expand to eternity.
Is the age of the universe shorter than the age of stars?
The age of the universe would be shorter than the age of oldest stars. This contradiction implies that either 1) our measurement of the Hubble constant is incorrect, 2) the Big Bang theory is incorrect or 3) that we need a form of matter like a cosmological constant that implies an older age for a given observed expansion rate.