The Big Bang Model Flashcards
What is the cosmological principle?
On a large scale the universe is homogeneous and isotropic - so it doesn’t have a centre
What does homogeneous mean?
Very part is the same as every other part
Why do astronomers disagree on the value of Hubble’s constant?
Distance is difficult to measure
Why did Hubble suggest the universe was expanding?
He observed red shift and blue shift
Why must the universe have been smaller and hotter in the past?
Because it is expanding and cooling down today
What is the rate of expansion of the universe all around us?
Uniform expansion away from us
We appear to be at the centre
What is the age of the universe if it has been expanding at the same rate its whole life?
t = 1/H₀
Why do cosmologists use dark energy to explain the expansion of the universe?
The expansion is accelerating
cosmic microwave radiation is evidence for what?
Hot big bang
What does isotropic mean?
everything looks the same in every direction
What does the amount of helium in the universe in the universe evidence before?
Hot big bang
