Chapter 26

25 July 2022
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An infinite universe is one of the assumptions of the cosmological principle.
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False
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The open universe would require Ωo be less than zero.
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False
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A critically bound universe is geometrically flat.
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True
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The closed universe would give the cosmos a spherical geometry in space-time.
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True
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If the density of the universe is at the critical density, then the geometry of the universe would follow ordinary Euclidean geometry.
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True
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The universe has been expanding at the same rate since its formation.
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False
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The fate or future of the universe depends only on the total number of galaxies and quasars.
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False
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All the known matter, both normal and dark, only gives us an Ωo of about .3.
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True
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A bound universe will ultimately end in a "cold death."
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False
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Einstein's cosmological constant is a leading candidate for the "dark energy."
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True
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Currently we think the matter accounts for only about 27% of the cosmos, with dark energy making up the rest.
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True
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The cosmological redshift is a direct measure of the expansion of the universe, thus independent of direction.
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True
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If the Hubble Constant is 70 km/sec/Mpc, the accelerating universe is about 10 billion years old.
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False
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The cosmic microwave background is the total of all the radio emissions from all the galaxies and quasars in the universe.
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False
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Olber's Paradox is solved in part by the fact that the universe is neither infinitely large nor infinitely old.
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True
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The Hubble constant divided into the number one gives a rough estimate for the age of the universe, or the "Hubble Time."
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True
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The cosmological redshift is actually not a velocity at all, but a measure of the expansion of space-time
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True
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The Big Bang was an expansion of matter into empty space.
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False
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The low density universe is an open one, with expansion continuing forever.
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True
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The open universe would be geometrically flat.
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False
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If the universe has a density greater than Ωo = 1, it is considered high density.
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True
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Homogeneity and isotropy, taken as assumptions regarding the structure and evolution of the universe, are known as:
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the Cosmological Principle.
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From the 1970s to the present, the accepted value of H has almost doubled, so:
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the age of the Universe is half what we believed.
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The center of the universe:
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does not exist anywhere in space.
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The sky is dark at night:
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because all the light from all the objects in the universe hasn't arrived here yet.
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What do most scientists believe existed before the Big Bang?
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nothing
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What was there just after the Big Bang?
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the primeval fireball
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What is the Big Bang?
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The event that started the expansion of the universe.
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Astronomers know the universe is expanding because:
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galaxies farther away are moving away from us faster.
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In which of the following models will the universe stop expanding?
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High Density Universe
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In which of the following models will the universe stop expanding? 2
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Closed Universe
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What is the meaning of a "closed" universe?
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The universe will someday stop expanding and begin collapsing inward.
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The concept that the direction of observation does not matter overall is:
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isotropy.
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If the density of the universe is greater than the critical density, this means that:
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the universe is expanding at a rate less than the escape speed of the universe.
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If the density of the universe is at the critical density, this means that:
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the universe is expanding at a rate equal to the escape speed of the universe.
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If the density of the universe is lower than the critical density, this means that:
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the universe is expanding at a rate greater than the escape speed of the universe.
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According to the data from the microwave background radiation, at what speed and in what direction is Earth moving through the universe?
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380 km/s in the direction of Leo
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The ratio of the universe's actual density to the critical density is:
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Ωo.
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If Ωo is less than one, then:
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the universe will expand forever.
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In the closed universe model, the geometry of spacetime in two dimensions resembles the surface of a:
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sphere.
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If the density of the universe is greater than critical, then:
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the universe is closed, gravity wins, and will shrink to the Big Crunch.
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In Robert Frost's classic poem, when he ends with "ice will suffice," the universe is:
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open.
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The concept that on the grandest of scales, the universe is similar in appearance everywhere is:
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homogeneity.
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On the surface of a sphere the shortest distance between two points is:
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an arc on a great circle.
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In a closed universe a beam of light will:
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come back to where it originated.
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When considering whether the density of the universe is above or below the critical density, what needs to be included in the measurement of density?
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ordinary matter, dark matter, neutrinos, gravity waves, electromagnetic energy and dark energy
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In an open universe two parallel beams of light will:
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diverge.
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If the presently accepted value of Ωo = 0.3 (excluding dark energy) is indeed correct, then the universe will:
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expand forever.
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The critical evidence for cosmic acceleration in 1998 came from two teams of astronomers, both observing:
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type I supernovae.
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The expansion rate of the Universe is:
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increasing.
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The universal accelerating force could NOT be considered:
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dark matter.
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The luminous matter in the universe accounts for what percent of the total mass of the universe?
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less than 4%
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In the critical density universe now proposed, the ratio of dark energy to matter is about:
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3 to 1.
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The two different kinds of surveys that have given astronomers great insight into the structure and expanse of the universe are:
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pie slice and pencil beam.
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The Wilkinson Mapping Project gave:
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Ωo = 1, but matter (dark and visible) is only 27% of this, the rest is dark energy.
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Recent work with type I supernovae at great distances suggests the universe may in fact be accelerating its expansion, a discovery attributed to a newly found:
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dark energy.
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In our best current theory, the first quasars formed about:
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13 billion years ago.
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In the critical universe now proposed, the ratio of matter/energy is about:
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27:73.
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The two teams involved in the discovery of the cosmic microwave background radiation were at:
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Bell Labs and Princeton.
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What temperature has the Big Bang has cooled to by now?
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Just over 2.7K
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The discovery of the cosmic microwave background was important because:
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it was experimental verification of a prediction from the Big Bang theory.
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According to the main sequence turn-off points of the oldest globular clusters, they are about:
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12 billion years old.
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The photons from the microwave background have not interacted with matter since the universe was how old?
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400,000 years old
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When the microwave background radiation was emitted, about how big was the universe?
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1/1,000 its currents size
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The Hubble time is expressed as:
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1/H.
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According to the microwave background radiation Earth is:
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moving at about 380 km/s toward Leo.
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The cosmic microwave background is:
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blueshifted in the direction of Earth's motion.
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While a variety of factors can produce redshifts in the spectrum, the one associated with the expansion of the universe is called:
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cosmological.
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The redshift of the galaxies is correctly interpreted as:
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space itself is expanding with time, so the photons are stretched while they travel through space.
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What does Hubble's law imply about the history of the universe?
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The universe had a beginning and has expanded since, giving it a finite age.
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The presently accepted value of the Hubble constant gives an age of:
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14 billion years.