Expanding Universe Flashcards
What is Dark Energy
The unidentified source of energy causing the accelerating expansion of the universe
What is Dark Matter
Material existing in space that we cannot detect - explains orbital speeds
Why should the expansion of the universe be decelerating?
The force of gravity should slow expansion
Why does the fate of the universe depend on its mass?
If the mass is large enough there will be a Big Crunch
If the mass is small enough there will be a Big Rip
Or expansion could go on indefinitely
How does the orbital speed of the sun determine the mass of our galaxy
Orbital speed of the sun is directly proportional to the mass inside of the orbit
Orbital speed -> gravitational force keeping it in orbit-> mass of galaxy inside orbit
How does the actual orbital speed of stars give evidence for dark matter?
The actual orbital speed of stars is greater than predicted which gives evidence of material inside galaxies which we cannot detect - dark matter
What is a stellar object?
a naturally occurring physical structure or entity that exists in the observable universe
Stellar objects emit radiation over a ….. range of wavelengths
Wide
Each object emitting radiation has a ….. wavelength which depends on its …….. and can use this to measure the ……. of a stellar object
Peak
Temperature
Temperature
Is peak wavelength shorter in hotter or cooler objects
Hotter
Hotter objects emit less radiation per unit surface area at all wavelengths than cooler objects. True or False.
False
Hotter objects emit more radiation at all wavelengths than cooler objects
How does Cosmic Microwave Background (CMB) radiation provide evidence for the big bang?
CMB radiation has been detected coming uniformly from all directions in the Universe. This suggests that it was produced at a single point and time. The big bang.
What is Olber’s paradox?
The darkness of the night sky suggests the universe is non -static (expanding)
What is Nucleosynthesis?
The ratio of hydrogen and helium in the universe is as expected if it were created in the early stages of the universe after the big bang
How does the temperature of the universe give evidence for the big bang
The average temperature of the universe is only 2.7k. This suggests that it has cooled down as it expanded after the big bang
