Lecture Questions 4

According to our textbook, roughly what percent of the mass and energy contents of the universe is made up of dark matter plus dark energy?

95%

How do astronomers know that there aren't significant amounts of dark matter within our solar system?

a lot of dark matter would affect the motions (orbits) of our spacecraft as the move through the solar system, and see no such effort

In the very distant future, given our best model of the accelerating universe, what will the universe look like?

all the stars will die and the galaxies will be dark

Where in space did the expansion of the universe begin?

everywhere at once

What do the surveys of the three-dimensional distribution of groups of galaxies reveal about how groups and clusters of galaxies are organized?

galaxy groups are organized into huge filaments with great voides between them -- something like the structure one would see taking a cross-section of some soap bubbles

According to the Cosmological Principle, the universe

is isotropic and homogeneous

Which of the following is not true about the Local Group of galaxies (of which the Milky Way is a member)?

it has about a thousand member galaxies

Which of the following did NOT happen during the first few minutes after the Big Bang?

some very massive early stars formed

Which of the following is pretty good evidence that the universe began with a Big Bang?

the fact that galaxies collide

If a very distant galaxy loks blue overall to astronomers, from this they can conclude that:

the galaxy must have alot of young stars and thus active star formation must still be going in it

What is the strongest known force in the universe?

the strong nuclear force

The standard bulbs (standard candles) that made it possible for astronomers to discover the acceleration in the expansion of the universe were

Type la supernovae

In which of the following domains of the universe have astronomers NOT found evidence for the presence of dark matter today?

the Solar System

If you wanted to write a complete "cosmic address" for yourself, including every location or structure you live in, which of the following would be that address?

Earth, the Solar System, the Milky Way Galaxy, the Local Group, the Virgo Supercluster

Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is

about 13.8 billion years

In our modern view of the expansion of the universe, we understand that is is space that is stretching; individual galaxies don"t speed away from each other as if they were rockets. In that case, why do galaxies show a red-shift?

as space stretches, the waves of radiation is space also stretch and their wavelength increases

Galaxies that we see as they were 11 billion years ago or more, as compared to galaxies today, are generally:

bluer and smaller

When astronomers say that the groups of galaxies are distributed isotropically, they mean that

the way galaxies are arranged in space looks the same in all direcetions