stars & galaxies: FINAL
*Life first appeared on earth* a) thousands of years ago b) billions of years ago c) hundreds of thousands of years ago d) millions of years ago
billions of years ago
*During the Cambrian Explosion,* a) most of the dinosaurs went extinct b) a significant amount of carbon was sequestered c) biodiversity increased significantly d) a significant amount of carbon was released into the atmosphere
biodiversity increased significantly
*The Anthropic Principle states that* a) if the universe were otherwise, life would not exist b) the universe was created in order to evolve life. c) life has made the universe the way it is. d) life exists, so the universe must be such that life can exist.
life exists, so the universe must be such that life can exist
*Scientists generally think life originated in Earth's* a) crust b) oceans c) atmosphere d) mountains
oceans
*The dominate force in the formation of galaxies is* a) gravity b) the strong force c) the weak force d) angular momentum
gravity
*The main difference between a prokaryote and a eukaryote is that prokaryotes like cyanobacteria* a) have no nucleus b) have no cell wall c) have no DNA d) do not exist anymore
have no nucleus
*GUT and TOE*
-TOE = the theory of everything -GUT = grand unified theory -the early universe, strong force + electroweak force = grand unified theory (GUT) -predicts proton decay -GUT + gravity = theory of everything
*The Cosmic Microwave Background includes information about (select all that apply):* a) density fluctuations of the early universe b) the density of the early universe c) the age of the universe d) the temperature of the early universe
-density fluctuations of the early universe -the density of the early universe -the age of the universe -the temperature of the early universe
*Where did the rest of the elements come from?*
-Big Bang Nucleosynthesis: •when colliding particles at very high energies and creating very high densities, the quarks inside the protons and neutrons become free •they are no longer trapped as protons or neutrons
*What is DNA / RNA?*
-DNA is responsible for storing and transferring genetic information -RNA directly codes for amino acids and as acts as a messenger between DNA and ribosomes to make proteins
*How does Einstein play a role in the discovery of the universe? Cosmological constant?*
-Einstein develops general relativity, which predicts the universe is expanding or contracting -He inserts an extra constant into his equations to make the universe stationary because he believes it should be -Einstein changes his mind, and describes his reluctance to accept the prediction of his original theory as "his biggest blunder"
*What is the Drake Equation?*
-Frank Drake and friends produced an equation that can be used to estimate the frequency of advanced civilizations in the galaxy -this equation requires educated guesses, and is generally thought of as a thought experiment -it is not a scientific equation that can be used to actually determine anything -simply a guiding principle -estimate the number of advanced civilizations using the Drake equation -Multiply: •number of stars in our galaxy •fraction of stars with planets •average number of planets per star •fraction of planets with life •fraction that develop advanced technology -the result is the likelihood such planets exist today
*Hubble Discovered The Expansion of the Universe...... when? How?*
-Hubble measured the redshifts of stars and galaxies -Realized by comparing redshifts and standard candles that galaxies further away are moving away faster -The universe is expanding -The expansion does not affect atoms, stars, or anything else, including laws of physics -The big bang happened everywhere -1920s
*Hubble's Law*
-Hubble measured the redshifts of stars and galaxies -realized by comparing redshifts and standard candles that galaxies further away are moving away faster -the universe is expanding -the distant galaxies we see in all directions are moving away from the Earth, as evidenced by their red shifts -hubble's law describes this expansion -the fact that we see other galaxies moving away from us does not imply that we are the center of the universe
*What is the fate of the universe expected to be? How do we know?*
-The fate of the universe depends on how much matter there is in the universe -Gravity from ordinary and dark matter slows the expansion -The faster the universe is expanding, the harder it is to stop it and make it contract -The more mass there is, the more gravity there is to halt the expansion -At the end of the 20th century we thought we understood the expansion -1990s: we were surprised to discover the expansion is speeding up -If the expansion were slowing, then the rate of expansion at earlier times should be larger than now -We see evidence that the expansion was instead smaller in the past, and larger now -The expansion is accelerating, not slowing down -This indicates that there is a type of energy in the universe that pushes on space, acting against gravity -This energy is called dark energy -This dark energy is associated with cosmological constant -Changes possible outcomes since it is more difficult for gravity to reverse the expansion
*What are genetic mutations?*
-a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people -mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes
*What is Dark Energy?* *Evidence for it?* *Possible explanations?*
-a type of energy in the universe that pushes on space, acting against gravity -associated with cosmological constant -changes possible outcomes for the universe since it is more difficult for gravity to reverse the expansion
*How old is the universe?*
-according to hubble, between 13.75-13.8 billion years old
*Galaxy Groups*
-aggregation of galaxies comprising about 50 or fewer gravitationally bound members -each at least as luminous as the Milky Way
*Applications of the theory of evolution include (select all that apply)* a) defeating the approaching robot uprising b) artificial selection c) managing antibiotic resistance d) vaccine engineering
-artificial selection -managing antibiotic resistance -vaccine engineering
*How does the expansion of the universe affect the light of distant sources?*
-astronomers observed that light from distant objects in the universe is redshifted (shift in the frequency of light towards red color), which tells us that the objects are all receding away from us -light that we think is 10 million light years away might actually be farther because the universe is expanding
*The Big Bang is a misnomer - why?*
-based on the observed expansion of the universe, there was a time when the universe was very hot and very dense -since the universe has been expanding ever since, and since the universe was very hot and very dense, we call it the big bang -***However, there was no bang, it was just a hot universe that started expanding, and cooling down -the name is misleading because there was no actual bang
*What is big bang nucleosynthesis?*
-big bang nucleosynthesis: collisions between protons (hydrogen nuclei) in the early universe formed low-mass nuclei, including deuterium, and isotopes of helium, lithium, beryllium, and boron -big bang nucleosynthesis correctly predicts the amounts of these isotopes found in the universe today -all elements more massive than boron formed in star
*Urey-Miller*
-chemical experiment that simulated the conditions thought at the time to be present on the early Earth -tested the chemical origin of life under those conditions -demonstrated that several organic compounds could be formed spontaneously by simulating the conditions of Earth's early atmosphere
*Galaxy Clusters*
-collections of galaxies larger than groups that are first-order clustering
*What problems does the string theory hope to solve?*
-combine general relativity and quantum theory into a single complete theory -resolve the problem of observer-dependence in quantum theory -determine whether the particles and forces in quantum theory can be unified -explain how the constants in the standard model of particle physics are chosen by nature -explain dark matter and dark energy
*Where is it thought to have first formed? why?*
-cyanobacteria -oceans
*What is the cosmic Microwave background made out of?*
-electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology
*What is a flat universe?*
-equal amounts of dark energy and matter -we have the right amount of matter to be considered a flat universe -Expansion force (dark energy) = contraction force (gravity) -spacetime is not curved
*Where have we found life on Earth?*
-everywhere on planet earth -originated in the oceans due to liquid water
*How has the evolution of the universe played out?*
-evolution proceeded at a slow pace over the next 3 billion years -DNA sequencing shows the interconnectivity of all species, establishing an evolutionary tree of life -possible reasons for the explosion include emergence from a period of extreme cold, an increase in oxygen and ozone, and an increase in genetic diversity -natural selection -natural selection has created a huge variety in 4 billion years, including humans -any system that combines heredity, mutation, and natural selection must, and will, evolve -theory of evolution is a mathematical framework that allows humans the ability to manipulate the natural world -based on the ideas of natural selection and mutation, we can predict how species will adapt to environmental changes -we can also predict when and how diseases will spread, mutate, and become unresponsive to treatments
*What is the theory of inflation? Why was it posited?*
-first proposed in 1979 by Alan Guth -imagines that the universe expanded very quickly for a few milliseconds after the big bang -this allowed the universe to stay in contact long enough to reach thermal equilibrium -this also flattened the geometry of the universe itself -case for the big bang is very compelling, but there are some puzzles to consider -a very rapid expansion at extremely early times -smooths and flattens the early universe -the inflationary big bang is the current most accepted model for the origin of the Universe -posits that in the very first fractions of an instant after the Bang, the young universe underwent an exponentially fast expansion (faster than the speed of light) -theory of inflation starts with the question: why is the night sky dark? -- Answer is olbers' paradox
*What is string theory? Why was it posited?*
-fully quantum mechanical by nature -replaces point particle and point waves with tiny strings and loops that vibrate -the different vibrations give the different particles -1 big problem: string theory makes no observable predictions so it has no complete formulation -explains gravity
*What did early galaxies look like?*
-galaxies form early, with structures, voids, and filaments forming later -the early universe should contain a lot of clumpy, irregular, distorted objects -gravitational instabilities in the early universe collapsed to form galaxies
*Are we at risk of another mass extinction event? What are some examples of "great filters" ahead of us?*
-great filter: whatever prevents dead matter from giving rise, in time, to expanding lasting life -no evidence of another extinction (its behind us) 9 STEPS TO EXPANDING -the right star system (including organics and potentially habitable planets) -reproductive molecules (e.g., RNA) -simple (prokaryotic) single-cell life -complex (eukaryotic) single-cell life -sexual reproduction -multi-cell life -tool-using animals with big brains -where we are now -colonization explosion one of these is improbable keeping us from expanding
*Which of the following elements are not found in DNA molecules?*
-helium, because you look for CHON when you look for life (Carbon, hydrogen, oxygen, nitrogen)
*What types of stars are likely to support life?*
-hotter stars because they have larger habitable zones
*What is life?*
-humans have tried to explain life for thousands of years -gaia hypothesis states that Earth itself is alive -we are finally able, through the tools of the scientific method, to understand what life is, enough to begin to engineer it -in order for life to exist, there must be something like DNA or RNA - a way for an organism to create proteins and pass blue prints on
*What elements were created in the 'big bang'?*
-hydrogen, helium, lithium, beryllium
*What is the idea of a multiverse?*
-idea that an infinite universe must repeat itself eventually -there could be other universes almost identical to ours -an infinite universe could contain an infinite number of disjointed, observable universes -our observable universe is finite -as far as we can tell, the universe itself is infinite. -this immediately means there are other, isolated, observable universes -Multiple observable universes in an infinite universe -Multiple futures in a quantum mechanical interpretation -Parallel universes: quantum choice universes, completely different mathematical universes
*What is the cosmic Microwave background radiation?*
-if all matter is in a small volume, it means conditions were very hot -due to expansion, light redshifted, and temperatures dropped -prediction: a blackbody spectrum uniformly redshifted by the expansion of the universe to a temperature of about 5 to the -10 power Kelvin -a blackbody spectrum with a temperature of about 3K was discovered in 1965 by Penzias and Wilson -the sky faintly glows in microwaves •cosmic microwave background (CMB) radiation •microwaves are from when the universe was young, hot, and ionized •at several hundred thousand years, the temperature cooled so protons and electrons could form neutral H atoms (recombination) •variations in the CMB: light variations in CMB give clues to the rise of structure in the early universe -- discovery and follow-up observations awarded Nobel Prizes in Physics -the light from the early universe is still reaching us today, this is the cosmic background radiation
*The expansion of the universe implies a time when the universe was hotter and denser... why?*
-if all matter is in a small volume, it means conditions were very hot -due to expansion, light redshifted, and temperatures dropped -since the universe has been expanding ever since, and since the universe was very hot and very dense, we call it the big bang -however, there was no bang, it was just a hot universe that started expanding, and cooling down
*What are the future prospects of String Theory*
-if proven it will be proven that we live in more than 4 dimensions -it will be the theory of everything as it will be the union of all the forces of nature -it's applications may prove multiverses and alternate dimensions
*What is the Fermi Paradox?*
-if we find life in all the parts of the earth in every location we look, shouldn't we find life in every other planet that has a system to form energy for life -the apparent contradiction between the lack of evidence and high probability estimates for the existence of extraterrestrial civilizations
*Where is the cosmic Microwave background located?*
-if you look back at the farthest thing you can see, at the very first light visible to our equipment, you're bound to reach something and it will be the CMB
*According to Hubble's Law, as a distance of a galaxy _____ its ________ increases* ON TEST
-increases -apparent recessional velocity
*Did the Big Bang happen at a single point? Why or why not?*
-it happened everywhere and all at once -before the Big Bang there was no universe -the Big Bang happened everywhere at once, about 13.75 billion years ago, bringing space and time into existence -the Big Bang kicked off a rapid expansion of space
*When did life on earth form?*
-life is a very complicated set of chemical reactions and interactions -definitive evidence dating back 3.5 billion years -some evidence life existed as far back as 3.65-3.85 billion years
*What ingredients are necessary for life like that on earth?*
-materials needed to make natural amino acids and lipids -cyanobacteria: photosynthetic prokaryotes able to produce oxygen -need carbon -need liquid water to exist (habitable zone)
*How do properties of the Cosmic Microwave background give support to the existence of dark matter?* ON TEST
-most of the cosmological information we get from the CMB is found by studying its power spectrum, a plot of the amount of fluctuation in the CMB temperature spectrum at different angular scales on the sky -the shape of the power spectrum is determined by oscillations in the hot gas of the early universe, and the resonant frequencies and amplitudes of these oscillations are determined by its composition -since we know the physics of hot gases very well, we can compute the properties of the oscillating gas by studying the positions and relative sizes of these peaks -the position of the first peak, for example, tells us about the curvature of the universe (and hence how much total stuff there is in it), while the ratio of heights between the first and second peaks tells us how much of the matter is baryonic (ordinary matter
*Why is inflation still controversial?*
-most scientists accept that cosmic inflation explains the earliest moments of the universe, yet the "big bang" remains more of an abstraction than full-fledged theory
*What properties do galaxy clusters exhibit?
-must be gravitationally bound to be considered a cluster -the speeds and properties of the orbits of the galaxies around the center of mass of the cluster indicate the presence of Dark Matter. -the strength of gravitational lensing by the clusters also indicate the presence of Dark Matter
*What temperature is the cosmic Microwave background?* *What temperature was it when it was first created? * *Why is the temperature so low now?*
-observations of cosmic microwave background show density of normal matter is very smooth -there is not enough normal matter to form structures: dark matter provides the seeds -dark matter is characterized by its average speed and its composition -cold dark matter: •slow speeds compared to c •candidates: unknown elementary particles •cold dark matter would work to form the observed large scale structures -hot dark matter: •moving rapidly •likely contributor: neutrinos from big bang
*Where have we observed life in the universe so far?*
-only on planet earth -but could exist in other areas in the past -life on earth is carbon based and needs water, there needs to be liquid water to find life in the solar system -Jupiter's moon Europa has liquid water oceans under the icy sheets -Saturn's moon Enceladus also has liquid water oceans -Mars definitely had liquid water in the past, and may have quite hospitable for life -Saturn's moon titan has a thick methane atmosphere, which could be a byproduct of life
*Cosmology*
-origin, expansion, structure, CMB, fate of universe
*What is natural selection?*
-self-replicating molecules will inevitably make a copying error -sometimes such a mutation is beneficial -the mutation may be more successful in self-replicating than the original -sfter a few generations, the molecules that were more successful at obtaining resources dominated others -competition, predation, and cooperation lead to natural selection: success breeds success -natural selection has created a huge variety in 4 billion years, including humans -any system that combines heredity, mutation, and natural selection must, and will, evolve
*Common characteristics of neutron stars*
-short rotation period -really small -source of pulsars -enormous magnetic field
*What is Dark Matter?* *Evidence for it?* *Possible explanations for Dark Matter are?*
-slows expansion of the universe -there is not enough normal matter to form structures: dark matter provides the seeds -characterized by its average speed and its composition -cold dark matter: •slow speeds compared to c •candidates: unknown elementary particles •cold dark matter would work to form the observed large scale structures -hot dark matter: •moving rapidly •likely contributor: neutrinos from big bang -the expansion of a dark matter clump is slowed by its gravity -its gravity pulls in normal matter, which radiates light and cools, then falls to the center -first stars must have formed in dark matter mini-halos -dark matter is inferred by normal matter motions observed via gravitational lensing
*What does the universe look like on large scales?*
-soap bubbles - filaments and voids, spongy -universe is uniform on large scales -observations of the large-scale structure provide direct evidence for the cosmological principle -large scale structure shows a homogenous and isotropic universe -cold dark matter would work to form the observed large scale structure
*Which of the following represents the unification of all fundamental forces?* ON TEST
-string theory
*Why was the Cosmic Microwave Background predicted?*
-the Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas within it cools -thus the universe should be filled with radiation that is literally the remnant heat left over from the Big Bang, called the "cosmic microwave background"
*The Big Bang Theory, when originally formulated, predicted (select all that apply): a) The regularity of Pulsars and other variable stars. b) The Cosmic Microwave Background c) The abundances of Hydrogen and Helium. d) The Origin of Species
-the Cosmic Microwave Background -the abundances of Hydrogen and Helium
*What is SETI?*
-the Search for Extraterrestrial Intelligence -organization has been active since the 1960s in trying to scientifically answer the question of are there other intelligent life forms out there? -listens primarily for radio transmissions with digital or artificial traits -searches for radio signals from technologically advanced civilizations
*Why do we think there was a big bang*
-the Universe is isotropic and homogenous -we observe that all galaxies are moving away from us at large scale -this means universe is expanding -this implies that in the past galaxies were closer together -> big bang
*Galaxy Superclusters*
-the groups and clusters of galaxies can themselves be clustered, into superclusters of galaxies -large group of smaller galaxy clusters or galaxy groups
*What is heredity?*
-the passing on of physical or mental characteristics genetically from one generation to another
*What is the habitable zone of a star?*
-the region around a star that provides a range of temperatures in which liquid water can exist is called the star's habitable zone -hotter stars have larger habitable zones
*Even with infinitely powerful telescopes we can look back in time only until the time when?* ON TEST
-the time of recombination
*What is the Standard Model?*
-there are forces that govern the universe: •gravity •electromagnetic •weak nuclear •strong nuclear -each came into being at a different time very early in the history of the universe -QED describes the electromagnetic force -electroweak describes QED + weak -standard model describes the combination of ideas in QCD (strong) and electroweak
*What role did prokaryotes play in creating the atmosphere we have today?*
-they are able to produce oxygen
*What are the various clusters our galaxy is a part of?*
-we are in the virgo cluster LANIAKEA -includes ~400 clusters, the Milky Way Galaxy and the -local Group -also includes the Virgo Cluster -contains over 100,000 galaxies
*Will the sun get larger over many billions of years?* ON TEST
-yellow dwarf -the sun is on the main sequence right now so it will continue to shrink till it looses its hydrogen -the sun will get brighter, increase in luminosity, increase in heat energy, which Earth's atmosphere will absorb -the center of the star contracts, its outer layers swell, redden and cool and it will die as a red dwarf
*What are the four fundamental forces of nature? describe*
1)GRAVITY: -general relativity explains how gravity works and its influences and effects -extremely low strength in our universe -requires huge amounts of matter to observe an effect 2)STRONG FORCE: -the theory of Quantum Chromodynamics explains how the strong force works -the strong force is 10^38 times more powerful than gravity -this force is what holds quark together, and therefore what holds protons and neutrons together in nuclei -without the strong force, the periodic table of elements wouldn't exist 3)WEAK FORCE: -the theory of Quantum Flavordynamics explains the weak force -the weak force governs radioactive decay, and is responsible for the physics involving nuclear power and radiation 4)ELECTROMAGNETISM: -governs the interactions of charged particles -E&M is used to engineer all communication and electrical devices, including transformers, magnets, copy machines, etc. -James Clerk Maxwell discovered that electricity and magnetism could be explained as two parts of the same theory (led to the theory of Electromagnetism) -Physicists in the 1960s realized that the weak force was actually part of the theory of electromagnetism, which led to the formation of one theory (quantum Electrodynamics) -we can only develop these combinations by studying the extra states of matter -this is similar to the physics of ice, water, and steam being 3 parts of the same underlying water molecules
*What steps are humans taking to understand inflation?*
BICEP: -South pole -looks for evidence of inflation -acone is pointed at a specific spot on the sky -Bicep 2 GW signal -a light come across the sky during inflation period & imprint red and blue light -specific polarization of light coming in from different parts of sky PLANCK: -predicts a nearly flat universe
*How has our understanding of the cosmic microwave background evolved?*
COBE -The Cosmic Background Explorer -referred to as Explorer 66 -satellite dedicated to cosmology, which operated from 1989 to 1993 -has a black body spectrum WMAP -Wilkinson Microwave Anisotropy Probe -measured temperature differences across the sky in the cosmic microwave background (CMB) - the radiant heat remaining from the Big Bang PLANCK: -Planck's law is the spectrum of a black body -stars are always moving away from each other because everything is expanded -as a photon moves it get really stretched -each photon builds up in energy and the temperature of the cosmic background is that of a black body
*What problems does inflation solve?*
FLATNESS PROBLEM: -spacetime gets curved because of massive objects & this gives us gravity -there is enough matter in the universe because there is enough matter -if you went out into space would you eventually come back to where you stared even though you think you're going in a straight line? •Yes, its just like the planets orbiting the earth •Because of the curvature of spacetime they feel as if they are going on a straight line but they end up where they start -we have the right amount of matter to be considered a flat universe -the combination Ωmass + ΩΛ is very close to 1 -the amount of matter present is just sufficient to halt its expansion, but insufficient to re-collapse it -Universe has exactly the required density of matter to be flat HORIZON PROBLEM: -different parts of CMB are not in contact -parts of the universe can't be in contact and 300,000 years after the big bang this contact should not be possible -the temperatures measured of the CMB photons across the sky are all nearly the same -this implies that these areas of the universe were in contact -this is impossible because the expansion of the universe -different parts of the earth reached thermal equilibrium because of inflation -the CMB is almost exactly the same temperature in all directions although these regions would have lost contact with each other long ago -arises due to the difficulty in explaining the observed homogeneity of causally disconnected regions of space in the absence of a mechanism that sets the same initial conditions everywhere -solution is cosmic inflation
*What is the difference between Doppler effect redshift and cosmological redshift?*
GAVITATIONAL: -caused by the expansion of spacetime itself DOPPLER EFFECT: -observers looking at an object that is moving away from them see light that has a longer wavelength than it had when it was emitted COSMOLOGICAL: -as light comes to us from distant galaxies, the space the light travels through expands, and the light is also stretched out -greater the distance traveled greater the redshift
*What does it mean for the universe to be homogeneous?* a) All stars in the universe have planetary systems like ours. b) Galaxies are generally distributed evenly throughout the universe. c) The universe looks the same from any perspective. d) The universe has looked the same throughout all its history.
Galaxies are generally distributed evenly throughout the universe
*difference between isotropic and homogenous*
ISOTROPIC: -the same in all directions HOMOGENOUS: -the same in all locations
*Is the Milky Way expanding like the rest of the universe?* a) No, it is the center of the expansion. b) No, its self gravity dominates over the expansion. c) Yes, slowly but surely. d) Yes, we are expanding towards Andromeda.
No, its self gravity dominates over the expansion
*What is the difference between a prokaryote and a eukaryote?*
PROLARYOTE: -a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles -include the bacteria and cyanobacteria EUKARYOTE: -an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus -include all living organisms other than the eubacteria and archaebacteria
*The Big Bang is* a) A supernova 100 billion times more powerful than a type 1A supernova. b) The beginning of space and time c) The collapse of a supermassive blackhole d) The absolute origin of everything.
The beginning of space and time for the observable universe
*What does it mean for the universe to be isotropic?* a) The laws of physics are the same anywhere in the universe. b) The universe has the same density everywhere. c) The universe looks roughly the same in every direction. d) More distant parts of the universe look just like nearby parts.
The universe looks roughly the same in every direction
*A fine-tuning problem is an example of* a) a property of the universe that seems hand picked for us to exist, at first glance, it could be anything, why does it have the value it has? b) physical constants being too far apart from each other. c) the difficulty of producing perfect physical theories. d) perfectly tuned musical instruments that produce a cosmic experience when played.
a property of the universe that seems hand picked for us to exist, at first glance, it could be anything, why does it have the value it has?
*A mutation is* a) always a beneficial change to DNA. b) a change to DNA that is not inheritable c) a sometimes beneficial and sometimes not beneficial change to DNA. d) never a beneficial change to DNA.
a sometimes beneficial and sometimes not beneficial change to DNA
*The famous Urey-Miller experiment produced ______________ in a laboratory jar.* a) life b) proteins c) RNA and DNA d) amino acids
amino acids
*When a particle and an anti-particle combine, they* a) create a micro black hole b) annihilate each other, releasing photons c) create heavier particles d) release huge amounts of energy
annihilate each other, releasing photons
*If the dark energy in the universe is constant, in the far distant future the universe will* a) collapse and re-form b) will be the same, just on larger scales. c) be bright and hot d) be cold and dark
be cold and dark
*Measuring the redshift of a galaxy's light tells us its* a) mass and velocity b) mass and distance c) distance and mass d) distance and velocity
distance and velocity
*Based on current observations, the universe is expected to* a) Stop expanding and become static. b) collapse back on itself into a Big Crunch. c) Instantly evaporate when 'the red button' is pushed. d) expand forever
expand forever
*Current observations describe a universe that is* a) flat b) inflating c) closed d) open
flat
*Near massive objects, spacetime is curved, and this causes gravity. However, on the scale of the universe, spacetime is* a) curved b) spheroidal c) saddle shaped d) flat
flat
*The cosmic background radiation is nearly the same level in all directions. This means those parts of the universe are in thermal equilibrium. This means they must have been in contact so their temperatures could equalize. However, the universe should have been too large for that to be possible at the moment of recombination. This is a statement of the* a) Flatness problem. b) Quantum Gravity problem. c) Horizon problem. d) Too many burritos problem
horizon problem
*What is the main difference between galaxy groups versus galaxy clusters?* a) how tightly they are bound by gravity b) the total mass of the galaxies c) there is no dark matter in galaxy groups d) the size of the largest galaxy
how tightly they are bound by gravity
*The Horizon problem is solved by the theory of* a) Expansion b) Hubble's Law c) Inflation d) the Big Bang Theory
inflation
*The Cosmic Background Radiation is uniform across the entire sky. This is an example of* a) thermal fluctuations b) anisotropy c) isotropy d) Wien's law
isotropy
*Big Bang nucleosynthesis predicts the relative abundances of which elements?* a) carbon, silicon, helium, chernobyl b) lithium, hydrogen, helium, and beryllium. c) uranium, plutonium, gold, platinum, silver d) helium, silicon, hydrogen, carbon
lithium, hydrogen, helium, and beryllium
*Quarks are* a) dark matter candidates b) normal matter subatomic particles c) little jokes that really aren't that funny unless you're in the right mood d) virtual particles
normal matter subatomic particles
*Astronomers measure that nearly all galaxies in the universe are moving away from the Milky Way Galaxy. This suggest that* a) space itself is expanding b) The Milky Way is the center of the expansion. c) The Milky Way is dope. d) the Milky Way is the center of the Universe
space itself is expanding
*We can measure cosmological redshifts by measuring the spectral lines of* a) rotation disks of galaxies b) individual stars in distant galaxies c) clouds of gas and dust in distant galaxies d) spectra of entire galaxies
spectra of entire galaxies
*Life on earth is carbon-based because carbon is* a) abundant b) water based c) radioactive d) tetravalent
tetravalent
*If repeated measurements of the current helium abundances in the universe continuously returned values lower than those predicted by the big bang theory, this would imply that* a) the Big Bang theory is incorrect or incomplete b) the measurements must be wrong c) scientists have no idea what they're doing d) the current helium abundances are wrong
the Big Bang theory is incorrect or incomplete
*Some galaxies are so redshifted, that the calculation of the velocity required to cause that redshift is faster than the speed of light. The theory of relativity is not violated in this case because* a) there is nothing stopping something from traveling faster than the speed of light. b) of Relativistic Beaming. c) the expansion of space is causing the redshift, not velocity through space. d) of "spooky action at a distance".
the expansion of space is causing the redshift, not velocity through space
*Measurements of gravitational lensing can be used to observe* a) dwarf galaxies near the Milky Way b) the masses of galaxy clusters c) the structure of laniakea d) dust and gas and low mass objects
the masses of galaxy clusters
*The critical-density of the universe is* a) The nickname of the largest Buick sold between 1981 and 1984. b) the matter density required to have a 'flat' universe. c) the density required to form a black hole. d) the density necessary to avoid degeneracy pressure.
the matter density required to have a 'flat' universe
*The Cosmological Principle states that* a) the early universe was 1,000 times hotter than it is now b) the rules that govern the universe are the same everywhere. c) the universe began with a bang d) the universe is expanding
the rules that govern the universe are the same everywhere
*The quickest and dirtiest way to estimate the age of the universe, to first order, is by using* a) the slope of Hubble's Law b) measuring the relative abundances of the elements. c) radiocarbon dating of moon rocks d) using models of the evolution of stars.
the slope of Hubble's Law
*Astronomers, no matter the technology invented in the future, will be unable to see further into space than the CMB, because* a) the universe is too large now b) photons did not exist at that time c) the universe was a dense "fog" at that point, and light from that part of the universe was not allowed to reach us. d) there was nothing actually too see
the universe was a dense "fog" at that point, and light from that part of the universe was not allowed to reach us
*Astronomers focus on stars with type F, G, K, and M as possible hosts of extraterrestrial civilizations primarily because* a) they have longer lifetimes which allows plenty of time for life to evolve. b) those stars are hot enough to have planets and moons with liquid water c) those stars are cool enough to have planets and moons with liquid water d) those stars don't produce harmful radiation
they have longer lifetimes which allows plenty of time for life to evolve
*The only thing we can reasonably conclude so far about the lack of evidence of alien civilizations in other solar systems is* a) there was an ancient interstellar galaxy wide war over black hole mining rights that results in all the aliens dying when they accidentally detonated a black hole. b) we don't know enough yet to draw any conclusions c) there are no aliens d) aliens are watching us and being very careful not to send us any signals.
we don't know enough yet to draw any conclusions
