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Astronomy 162, Stars, Galaxies, and the Universe, is part 2 of a 2-quarter introductory Astronomy for non-science majors taught at The Ohio State University. This podcast presents lecture audio from Professor Richard Pogge's Winter Quarter 2006 class. All of the lectures were recorded live in 1008 Evans Laboratory on the OSU Main Campus in Columbus, Ohio.
 
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In this episode, we debut our new theme music! Bioshock Infinite nearly takes over the show, and we have our first official segment of the Building Blocks, to discuss what a bad game is and what we can learn from it.저자 Men of Destiny
 
How can we search for extraterrestrial intelligence, and what are welooking for? This second part of a 2-part lecture picks up where weleft off yesterday by examining SETI, the Search for ExtraTerrestrialIntelligence, and reviews what we might look for and how. We will usethis as a point of departure to then briefly review where we have comeand wha…
 
Are we alone in the Universe? This is the first part of a 2-partlecture that will explore the question of life and the Universe. Wewill look at the conditions needed for life, and address the question ofhow often we expect those conditions to be satisfied in our own Galaxy.In this part, we introduce the Drake Equation and make some basicestimates. …
 
Can we travel through time? This is not a frivilous, science-fictionkind of question. Certain restricted kinds of time travel are in factallowed by classical General Relativity. This lectures takes up thisquestion, and looks at some of the surprising answers that have beenfound. Recorded 2006 March 8 in 1008 Evans Laboratory on the Columbuscampus o…
 
We are not made of the same matter as most of the Universe! Thissurprising conclusion, that the ordinary matter we are made of (protons,neutrons, and electrons) constitute only 13% or so of the total matterin the Universe, the rest being in the form of Dark Matter. Further,this dark matter is only about 30% of the combined matter and energydensity …
 
How will the Sun evolve? The Sun is now a middle-aged, low-mass, MainSequence star in a state of hydrostatic and thermal equilibrium that hasconsumed about half of the Hydrogen available for fusion in its core.What will its subsequent evolution be as its core runs out of Hydrogen?This lecture describes our current state of understanding of theexpec…
 
What is the ultimate fate of the Universe? The ultimate fate ofthe Big Bang is either expansion to a maximum size followedby re-collapse (the Big Crunch) or eternal expansion into a cold,dark, disordered state (the Big Chill). Which of these is ourfuture depends on the current density of matter and energy in theUniverse, Omega0. This lecture examin…
 
What was the Universe like from the earliest phases immediately afterthe Big Bang to the present day? This lecture reviews the physics ofmatter, and follows the evolution of the expanding Universe from thefirst instants after the Big Bang, when all 4 forces of nature wereunified in a single grand-unified superforce until the emergence of thevisible…
 
Is there any evidence that the Universe was very hot and densein the distant past as predicted by the Big Bang model of theexpanding Universe? This lecture examines observational testsof the Big Bang Model. We have already covered expansion in theprevious lecture. Today we look at Primordial Nucleosynthesis, the creationof light elements from fusio…
 
The Universe today is old, cold, low-density, and expanding. If we runthe expansion backwards, we will eventually find a Universe where allthe matter was in one place where the density and temperature are nearlyinfinite. We call this hot, dense initial state of the Universe the BigBang. This lecture introduces the Big Bang model of the expandinguni…
 
How do we measure distances on cosmic scales? This lecture describesthe rungs in the cosmic distance ladder from measuring the AU in ourown Solar System out into the Hubble expansion of the universe. Thesedistances form the basis of the measurements that let us piece togetherthe present, past, and future history of the expanding Universe, settingth…
 
How did we discover that the Universe is Expanding? What doesit mean that it is expanding? This lecture introduces Hubble's Law,the observational evidence that the Universe is systematicallyexpanding. As galaxies get more distant from us, the apparent speedof recession gets larger in proportion. The proportionality is therate of expansion, called t…
 
What are the implications of Relativity for the Universe? This lectureintroduces the Cosmological Principle, which states that the Universe isHomogeneous and Isotropic on Large Scales. Applying this to histhen-new General Relativyt, Einstein got a surprise: the Universe musteither expand or contract in response to all the matter/energy thatfills it…
 
What is gravity? Newton left that question unanswered when he formulatedhis inverse square law of the gravitational force, framing no hypothesisfor what agency transmits gravity, only asserting it was an actionat a distance. Einstein brought gravity into relativity by answeringNewton's unanswered question with his General Relativity, our moderntheo…
 
What are space and time? To begin our exploration of the evolvingUniverse, we must first understand what we mean by space and time.This lecture contrasts the Newtonian view of the World, with itsabsolute space and absolute time, with that of Einstein, who showedthat space and time were not absolute but relative constructs, andthat only spacetime, u…
 
What are Active Galaxies and Quasars? We have good reason to think that buried deep in the hearts of nearly every (?) bright galaxy is a supermassive black hole with masses of millions or even billions oftimes the mass of the Sun. Most, like the one in our Milky Way, are quiescent, but in about 1% of galaxies, they are fed enough matter(up to about…
 
What happens if two galaxies collide? The average distance betweenbright galaxies is only about 20 times their size, so over the historyof the Universe (14 Billion years), we expect that most bright galaxieswill have had at least one close gravitational encounter with aneighboring galaxy. This lecture explores what happens when twogalaxies undergo …
 
Galaxies are found in groups and clusters, and these are only thestart of a hierarchy of cosmic structures up to the largest scalesobserved. This lecture introduces the properties of groups andclusters of galaxies, superclusters (clusters of clusters), andlarge scale structure with filaments of superclusters surrouningvast voids. We start with our …
 
What are the different types of galaxies? What hints can they giveus as to the structure and evolution of galaxies? This lectureintroduces the Hubble Classification System for galaxies, and describesthe properties of each major class. This detailed overview gives ussome tantalizing clues as to the formation and evolution of galaxiesthat will be pic…
 
What are Spiral Galaxies? This lecture describes the basicproperties of spiral galaxies, their patterns of rotation andhow that lets us measure their masses, and the nature of thespiral arms as waves moving through the disk and triggeringformation of new stars.Recorded 2006 February 10 in 1008 Evans Laboratory on the Columbus campusof The Ohio Stat…
 
Andromeda is the nearest bright spiral galaxy to the Milky Way, and a neartwin in terms of stellar and gas content. This lecture discussesthe idea of stellar populations and chemical evolution in galaxiesas determined by combining observations from within (the Milky Way) andwithout (Andromeda). At the end, two other features of these galaxies,their…
 
How did we come to understand that the Milky Way was just one ofbillions of other galaxies in a vast Universe? This lecturereviews the history of how we came to recognize that the spiral nebulaewere, in fact, other milky ways like our own: vast systems of 100s of billions of stars located millions of parsecs away. Thekey to understanding their natu…
 
What is the Milky Way, and what is our place within it? This lectureintroduces the Milky Way, the bright band of light that crosses thesky, and describes how we came to our present understanding of the sizeand shape of the Milky Way Galaxy, and our location in it.Recorded 2006 February 7 in 1008 Evans Laboratory on the Columbus campusof The Ohio St…
 
How do we measure distances to astronomical objects that are too faraway to use Trigonometric Parallaxes? This first lecture of Unit 4reviews geometric methods like trigonometric parallaxes, and thenintroduces the idea of Standard Candles, and how they are used todevelop methods for deriving Luminosity Distances based on the InverseSquare Law of Br…
 
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