17 Questions
What can be inferred about the motion of galaxies from the observation of redshift?
Galaxies are moving away from us
What is the physical significance of the slope of the Hubble Law Graph?
It represents the velocity per unit distance
What is the unit of the Hubble Constant?
m/s/Mpc
What is the estimated age of the universe based on the Hubble Constant?
8 to 15 billion years
What is the range of the Hubble Constant in km/s per megaparsec?
50 to 100 km/s/Mpc
What is the relationship between a galaxy's distance from us and its velocity through space?
Velocity increases as distance increases
Why are distances to galaxies typically measured using Cepheid variable stars or supernovae?
Because they have a known brightness
What is the significance of the Big Bang Theory?
It explains the origin of the universe
What can be inferred about the universe from the observation of galaxy recession?
Galaxies were once much closer together
What is the term used to describe the distance between galaxies and their recession velocity?
The Hubble Constant
What can be inferred about the universe's age from the expansion process?
The universe is approximately 15 billion years old
What is the primary difference between the expansion of the raisin bread model and the expansion of the actual universe?
The raisin bread expands into a pre-existing space, while the universe expands into itself.
What is the key insight that can be gained from the observation of the raisins in the expanding loaf of bread?
The space between objects in the universe is expanding, but the objects themselves are not.
What is the relationship between the distance and velocity of objects in the uniformly expanding loaf of bread?
The velocity of objects is directly proportional to their distance from the observer.
What is the significance of the initial singularity in the raisin bread model?
It represents the point at which space and matter were indistinguishable.
What is the role of the yeast in the raisin bread model?
It is merely a mechanism to illustrate the expansion of the bread, and has no cosmological significance.
What is the implication of the expanding loaf of bread on our understanding of the universe's size?
The universe is expanding, and its total size is increasing.
Study Notes
Hubble's Law
- Almost all galaxies are redshifted, indicating they are moving away from the Milky Way.
- The most distant galaxies exhibit the greatest redshift, meaning they are moving away from us the fastest.
Hubble Constant
- The slope of the Hubble Law graph represents the Hubble Constant, expressed as velocity/distance (km/s/Mpc).
- The Hubble Constant has dimensions of 1/s, so the reciprocal of the Hubble Constant (1/H) has dimensions of time, measured in seconds.
- The Hubble Constant is estimated to be between 50 and 100 km/s per megaparsec.
Implications of Hubble's Law
- The universe has been expanding for 8 to 15 billion years, as inferred from the Hubble Constant.
The Expanding Universe Cosmology
- The search for origins is a fundamental aspect of human curiosity, and the Big Bang Theory is a result of several important observations.
The Big Bang Theory
- In 1927, Edwin Hubble observed that galaxies are redshifted, indicating they are moving away from us.
- The farther away a galaxy is from Earth, the faster it is receding.
- This observation suggests that the universe is expanding, and galaxies were once closer together.
The Hubble Constant
- The Hubble Constant is the rate at which galaxies are moving away from us, estimated to be between 50 to 100 km/s per kiloparsec.
- Measuring the recessional velocity of galaxies is easy, but determining their current positions is challenging.
- Distances to galaxies are typically measured using Cepheid variable stars or supernovae with known brightness.
The Origin of the Universe
- Running the expansion process backward suggests that the universe took approximately 15 billion years to reach its present size.
- The expansion process implies that some event, known as the Big Bang, caused the galaxies to move away from each other.
Hubble's Law
- The graph shows a direct relationship between a galaxy's distance from us and its velocity through space.
- The farther away a galaxy is from us, the faster it is receding from us.
The Raisin Bread Model
- The raisin bread model represents the expansion of the universe, where the dough (space) expands, and the raisins (matter) move away from each other.
- The expansion of the dough does not affect the size of the raisins, illustrating that the matter in the universe is not expanding.
- The space around the matter is expanding, consistent with the principle of conservation of mass.
- The velocity of distant objects is directly proportional to their distance away from us, as observed by Hubble.
Understand the implications of Hubble's Law, including galaxy redshift, velocity, and distance. Learn about the Hubble Constant and its significance in astronomy.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
