Astronomy Final Practice

a “light year” is a unit of…

distance

By viewing progressively more distant object…

astronomers look further back in time

Because of weathering and plate tectonics…

studies of Earth’s crust reveal very few rocks whose ages exceed 3 billion years

The James Webb space telescope’s infrared-observing design is advantageous because…

clouds of gas and dust do not block infrared light as much as optical light.

Of what does “white light” consist (are there actually any other colors?), and how do we know?

it consists of all the colors of the rainbow, not a pure color but a mixture of light of all visible wavelengths (how our eyes perceive a mixture of all the colors in the visible spectrum.) You can see the component colors if you pass white light through a prism or raindrop, forming a rainbow or spectrum,

Two reasons for thinking that there may be multiple universes

• if our Universe was created initially by quantum fluctuations out of nothing, then maybe many of these quantum fluctuations could have occurred, resulting in many universes.

• while our Universe was undergoing inflation, regions of it may have undergone phase transitions in different ways. These regions could have different physical constants, and they would be separated from each other and not able to contact each other. Many of these separate, distinct, inflating regions could occur, creating essentially separate universes.

• while some parts of the inflating Universe undergo the phase transition and stop inflating, other parts don’t do this and keep inflating, thus producing large regions that are essentially disjoint from our Universe.