Cosmology Flashcards
How can we measure the passage of time?
By watching something change, e.g.
The apparent movement of the sun across the sky.
The seasons.
What is the universe moving from, and what’s this called?
The universe is naturally moving from order to disorder, and this is called the arrow of time.
What is entropy?
It is a measurement of disorder.
What does high entropy have?
Disorder
What does low entropy have?
Order
Is the universe moving to high or low entropy
High entropy = disorder
How old is the universe?
The universe is 13.8 billion years old.
What is scientific notation?
It is a shorthand way of dealing with very big or very small numbers.
How do you convert big numbers to scientific notation?
Move the decimal point over to the left.
100000 = 1x10(5)
How do you convert scientific notation into a number?
Move the decimal point to the right.
1x10(5) = 100000
How fast is the speed of light?
The speed of light is 300,000,000 m/s, it is also the greatest speed achievable in the universe.
What is the speed of light’s symbol?
C = celerity
What equation links speed, distance and time?
V = d/t
V = velocity
D = distance
T = time
What are we doing when we see a star in the night sky?
We are looking back in time.
How are we looking back in time when we look at stars?
Stars are extremely far away.
Even though light is travelling at the fastest possible speed achievable, it takes a very long time for light to travel to earth. The light left the star in the past. When we see a star what we see is a picture of what the star looked like when the light left.
