Life in Our Universe

Course No. 1898
Professor Laird Close, Ph.D.
The University of Arizona
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Course No. 1898
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Course Overview

Are we alone in the universe? Or does the cosmos pulse with diverse life forms? This is one of the most profound issues facing mankind—and one of the unresolved questions that science may finally be able to answer in this century. Both scenarios are mind-boggling and, to quote futurist Isaac Asimov, equally frightening. No matter what the answer, the implications are vast.

If even the most rudimentary life forms could be found elsewhere in our universe, it would be a paradigm-shifting revelation on par with discovering the atom. Finding microbes in an extraterrestrial location would dramatically increase the chances of life being common everywhere, and encountering intelligent life would forever alter our place in the cosmos.

There has never been a better time to study our universe. NASA's Kepler mission, the first dedicated extrasolar planet-finding spacecraft, is rapidly changing what we understand about planets around other stars. At present, it has detected hundreds of confirmed planets, and well over 2,000 likely new planets have been identified. And exponential growth in telescope power and other critical technologies is enabling scientists to make new discoveries every day.

Life in Our Universe reveals the cutting-edge research leading scientists to believe that life is not exclusively the domain of Earth. Taught by Dr. Laird Close, an award-winning Professor of Astronomy and Astrophysics at The University of Arizona, these 24 mind-expanding lectures offer an unparalleled look at the subject of life and the mysteries that remain. Supported by stunning visuals, this course shares some of the most intriguing discoveries that the fields of astronomy, biology, geology, chemistry, and physics have to offer.

You'll examine the remarkable coincidences that created our planet and sustained its habitability for 3.5 billion years. And you'll join the hunt for microbial life elsewhere in our solar system and Earth-like planets in alien solar systems—one of astronomy's "holy grails."

Discover the New Field of Astrobiology

Life in Our Universe offers unprecedented access to the new and exciting field of astrobiology. Until recently, universities didn't even offer astrobiology courses, and such courses are still quite rare. With Professor Close's expert guidance, you'll delve into some of the biggest questions facing science today, including the five that shape this course.

  • What can the Earth and its current and past life tell us about life in our universe?
  • Where else in our solar system can there be life?
  • Are there habitable planets and life around other stars?
  • Is there other intelligent life in our universe?
  • Is there a new home for mankind? If so, how can we find it?

You'll rewind 13.7 billion years to the big bang, when the first stars and galaxies took shape. Then, you'll fast-forward to see how a series of mishaps and cataclysmic events set the stage for early Earth—a dead planet—to become a "lucky planetesimal" that blossomed with life.

You'll learn in detail how, in its first 650 million years, Earth sustained repeated massive impacts during a period dubbed the Late Heavy Bombardment, leaving it trapped in a lifeless state devoid of a stable atmosphere or oceans.

DNA and RNA traces of humans and single-celled extremophiles help you understand how early life quickly evolved from a single common ancestor once the bombardment ceased.

You'll look closely at

  • the importance of liquid water, and whether another liquid might be capable of supporting life;
  • how Earth has maintained habitable temperatures despite fluctuations in oxygen;
  • how tiny microbes from outer space may be bombarding the Earth with regularity;
  • stars, and why their death makes our galaxy more habitable over time; and
  • critical issues surrounding terraforming, a process by which a planet such as Mars would be made more Earth-like.

You'll also investigate practical limitations to space travel—despite what science fiction would have you believe—and the astounding loopholes that would open if flat spacetime could be bent through "warp drive" or "wormholes."

Earth Is Not Your Average Planet

As you explore the planet-formation process, you'll see how it left the solar system teeming with asteroids and comets, which enriched the early Earth, and learn several properties that made Earth the most likely planet in our solar system to host life.

Find out how Earth benefited from

  • its position in the "Goldilocks Zone," just the right distance from the sun;
  • a continuously hot core powering volcanoes;
  • magnetic fields that shield us from solar winds; and
  • a large, stabilizing moon that prevents deserts from turning into polar regions and vice versa.

As you venture beyond our planet to other locations in our solar system, you'll come in contact with the ancient Martian highlands, the hellish surface of Venus, and Saturn's planet-like moon, Titan. Jupiter's moon Europa will be of particular focus—and a source of fascination—as you explore the possibility that an organism-filled liquid-water ocean lies beneath its frozen surface.

Travel beyond Our Solar System

The latter part of this intellectual adventure takes you in search of extrasolar Earth-like planets that may host—or at least be hospitable to—life. Here, you'll overview the practice and potential dangers of SETI, the search for extraterrestrial intelligence, and consider its viability in light of advances in technology and the galaxy's vastness.

In another lecture, you'll confront the startling reality that humanity will have to leave Earth or risk extinction in the distant future—an inevitability motivating astronomers to search for a new home in our solar "neighborhood." But, as the professor says, a good Earth is hard to find.

Professor Close breaks down what scientists are looking for in an extrasolar Earth, as well as the exciting breakthroughs in adaptive telescope optics that will allow the next generation of terrestrial and space-based telescopes to directly detect biomarkers across the cosmos.

As a scientist at the forefront of this field, he masterfully explains how this technique overcomes the atmosphere's blurring effect to create the extremely sharp images that allow new alien solar systems to be directly imaged.

A Visual Journey through Space

Remarkable NASA graphics and images, artistic renderings, custom interstellar animations, and planetary photographs the professor has captured in his research bring course concepts vividly alive.

Suited for the scientifically inclined and curious alike, these lectures are presented in a clear, engaging manner that makes even the most complex content highly accessible. Far from being an ivory-tower academic, Professor Close, an adaptive optics expert, has invented several cameras used for high-resolution imaging of stars and their planets and has been an integral part of many significant discoveries.

Armed with the recent findings you encounter in Life in Our Universe, you'll possess the essential context necessary to make sense of the news on emerging discoveries, including their implications—and you'll have a whole new way of looking at life.

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24 lectures
 |  Average 30 minutes each
  • 1
    Is There Life Elsewhere in Our Universe?
    Is there life in our universe? As you get an overview of the course—including the five major questions it will endeavor to answer—consider the possibility that life exists in some form in the cosmos. Learn how exponential growth in technological developments is enabling breakthroughs that were recently impossible. x
  • 2
    Bang! A Universe Built for Life
    How did we go from a dead universe to a universe full of life? Begin to answer this question by evaluating the scientific evidence supporting the big bang theory of the universe's creation, and learning the role stars play in creating carbon and the key elements needed for life. x
  • 3
    A Star Is Born—Forming the Solar System
    How do you make a planet? Look at what is currently known about the process by which our solar system's planets formed from billions of small planetesimals, as well as how this process left the universe teaming with asteroids and comets that play an important role in life on Earth. x
  • 4
    The Early Earth and Its Moon
    Follow a series of mishaps and cataclysmic events that set the stage for early Earth to finally flourish with life after 650 million years. Learn how a hot core, a large moon, and other properties on Earth helped lead to an active biosphere. x
  • 5
    Impacts—Bringers of Death … or Life?
    Delve into the Late Heavy Bombardment period that kept Earth stuck in a lifeless state for 650 million years, then watch an animation demonstrating the K-T impact event that wiped out the dinosaurs. Consider whether it's possible to protect ourselves from asteroids hurtling toward Earth—and why Hollywood gets it all wrong. x
  • 6
    Evidence of the First Life on Earth
    How has the Earth managed to stay within a moderate range of temperatures for billions of years, despite the atmosphere's wild fluctuations in oxygen? Study how convection, greenhouse gases, and the carbon rock cycle contribute to a powerful system of checks and balances that keep Earth's climate consistent with supporting life. Also, meet some of Earth's earliest life. x
  • 7
    Common Themes for All Life on Earth
    Now that you have covered the key elements necessary for life to exist, take a closer look at the things all life on Earth shares. Learn why the Biosphere 2 experiment in the 1990s failed, examine the behavior of microbes—the most important constituents of our biosphere—and trace life back to your universal ancestor. x
  • 8
    Origin of Terrestrial Life
    For something to be "living," it generally must use energy to drive chemical reactions, be capable of reproduction, and undergo some degree of evolution. Sort through science's best educated guesses for how and why life sprang from nonliving matter, including lessons from the groundbreaking Miller-Urey experiment. Watch an animation of protocells growing and splitting to replicate genetic information. x
  • 9
    Astrobiology—Life beyond Earth
    Why is liquid water so important? Why do icebergs float? After quickly reviewing what you have learned about the requirements for terrestrial life, take a closer look at the "liquid water carbon chemistry juggernaut," which allows organic life to thrive on Earth. Consider whether other liquids could operate as solvents for life. x
  • 10
    Has Mars Always Been Dead?
    Mars ranks as NASA's number one priority in the search for exolife. Here, you delve into why Mars is so intriguing to astrobiologists and what the search has found to date. Start with a comparison of Mars and the Earth, then watch the first-ever observation of water ice on Mars sublimating into vapor. x
  • 11
    Evidence for Fossilized Life from Mars
    In 1996, NASA claimed to have found evidence of past life on Mars inside an unassuming meteor. Evaluate the three points scientists gave in support of the microbes being Martian in origin to determine their validity. Then, learn about the theory of panspermia and meet the water bear, a tiny animal capable of surviving the extreme conditions of outer space. x
  • 12
    Could Life Ever Have Existed on Venus?
    Venus is the closest planet to the Earth and the next planet moving toward the sun, so it is a logical place to look for life. However, Venus is extremely hot and dry. Could life ever have existed? Explore the nightmarish conditions on Venus and learn why all the water vanished. x
  • 13
    Liquid Assets—The Moons of Jupiter
    Gas giant Jupiter is unlikely to inhabit life—but what about its moons? Look quickly at the importance that Galileo's discovery of Jupiter's moons had for the powerful Medici family before moving on to examine the connection between the moons' mean motion resonance and the possibility of subsurface life existing in the ice-covered oceans of Europa, Ganymede, and possibly, Callisto. x
  • 14
    Liquid on Titan and Enceladus
    Continue traveling to the cold gas giant Saturn and its large moon, Titan. Watch a video featuring actual data taken by the Huygens Probe as it pierces the thick atmosphere and lands on the surface of this frozen world, and witness the surprising Earth-like structures this probe and its mother ship found on their journey to Saturn's moons. x
  • 15
    Discovery of Extrasolar Planets
    Is our solar system common or rare? As you investigate planets orbiting around other stars, learn how the use of adaptive optics allows extrasolar planetary scientists to discover new alien solar systems with ground telescopes, and explore the three main ways astronomers detect planets: small "radio velocity wobbles," "transits," and direct imaging. x
  • 16
    The Kepler Spacecraft's Planets
    The Kepler mission is changing everything we know about extrasolar planets. Learn how this supersensitive-imaging instrument works to monitor 157,000 stars continuously for years and what it has uncovered since launching in 2009. But first, review the transit effect created when a parent star crosses its orbiting planet. x
  • 17
    A Tour of Exotic Alien Solar Systems
    Based on data from Kepler, there are thought to be four main classes of transiting planets: hot Jupiters, hot Neptunes, super-Earths, and Earth-like planets. In this lecture, you will look at detailed highlights of the most fascinating examples of each of these new classes of alien worlds, from most to least massive. x
  • 18
    Extraterrestrial Intelligent Life
    How common is simple life is in our universe? What about intelligent life? Start to answer these questions by estimating the prevalence of prokaryotic single-celled microbes and reviewing the process of evolution. Evaluate arguments in the book Rare Earth by Ward and Brownlee claiming that while microbial life is common, only Earth has intelligent life. Finally, touch on how aliens might appear. x
  • 19
    SETI—The Search for Intelligent Life
    In a lecture that "skims right on the edge of science fact and science fiction," delve into the search for extraterrestrial life, or SETI, as the method used to gauge the likelihood of intelligent communicating civilizations is known. Look closely at the Drake Equation—the mathematical rubric commonly used in the field of SETI—and consider the challenge of communicating across our enormous galaxy. x
  • 20
    The Fermi Paradox—Where Is Everyone?
    After 50 years of SETI, we have zero hard evidence of alien civilizations, "cosmic wanderlust" resulting in Earth visitations, or UFOs being extraterrestrial in nature, despite—or perhaps because of—the expansiveness of the galaxy. Speculate on reasons for, and solutions to, this so-called Fermi Paradox. x
  • 21
    Space Travel—A Reality Check
    Space is so vast that inventing a method of faster-than-light travel is the only way humans could conceivably travel the cosmos conveniently. How hard is space travel, really? In this mind-bending lecture, review the obstacles to space travel and consider their theoretical solutions—from combining matter and antimatter into energy, to taking "short cuts" via warp drive and wormholes. x
  • 22
    Terraforming a Planet
    Terraforming is a new scientific concept whereby an uninhabitable planetary environment is engineered to become more Earth-like to support human life. Explore how this complex process would play out on the two planets considered potential candidates, Mars and Venus, to fully understand the individual steps involved and the technologies necessary to achieve those steps. x
  • 23
    The Future of Terrestrial Life
    Professor Close highlights why we shouldn't be complacent about the long-term viability of Earth and presents the timescale in which humans will need to leave Earth or become vulnerable to extinction. Inspect historical evidence indicating that Earth is warming, and learn what will happen to the atmosphere in the future. x
  • 24
    The Search for Another Earth
    Now that you've seen why humanity will eventually have to leave Earth, consider astronomers' next steps, challenges, and planned missions. Examine why specialized optical systems called coronagraphs are necessary to detect habitable Earths, and how the use of direct imaging spectra is crucial to identifying whether the biomarkers of life are present on other worlds. x

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  • 24 lectures on 4 DVDs
  • 157-page printed course guidebook
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What Does The Course Guidebook Include?

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Course Guidebook Details:
  • 157-page printed course guidebook
  • Photos & illustrations
  • Suggested readings
  • Astrobiological Timeline

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Your professor

Laird Close

About Your Professor

Laird Close, Ph.D.
The University of Arizona
Dr. Laird Close is Professor of Astronomy and Astrophysics at The University of Arizona. Awarded a Canadian (study abroad) Natural Sciences and Engineering Research Council scholarship while attending The University of British Columbia, he then earned his Ph.D. in Adaptive Optics from the renowned University of Arizona Astronomy Department where he now teaches. Professor Close has been highlighted as an outstanding professor...
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Life in Our Universe is rated 4.0 out of 5 by 43.
Rated 5 out of 5 by from fantastic stuff this was a real eye opener. Really enjoyed a practical approach to all of this. Of course, this is limited by our knowledge of science, but within newtonian and einsteinian physics he does a great job of dismissing the pop sci fi ideas about extraterrestrial travel, visits, life on other planets, terraforming, etc. Not that they can't happen; just that given what we DO know about our concept of life and the makeup of the universe, these are the restraints. I've always felt extraterrestrial life was a given considering the numbers of stars and potential planets but after listening to this and the criteria for life based on what we know, i agree now with the perspective that life elsewhere may be relatively uncommon. Enthusiastic and riveting professor and subject.
Date published: 2020-10-03
Rated 4 out of 5 by from Life from an Astronomer/Physicist Perspective During the first few lectures I thought that there was not going to be very much depth to the course. Other TC courses have covered the formation of the universe more fully and completely. OTOH, every course needs some introductory material, often at a surface level, so I was not too put off. About halfway into the course, I realized that much of the material is presented with no explanation at all as to its authenticity or why one should believe that it has merit. For example (and as another reviewer has noted) noting the telltale adsorption line of helium. This approach probably makes sense, as the course is not meant to teach us about such subjects and it really makes it easer for those with little hard science background to grasp the larger concepts. Even so, when the course shifts to areas touching of Professor Close’s expertise, we are provided with a fair amount of detail (e.g. adaptive optics). Other reviewers have noted Dr. Close’s repeated use of the word “actually”, but I did not find it off putting. However there was a distinct lack of dynamic passion in the presentation. Dr. Close is no showman, even when using his props, some constructed by him. The overall production values of the course are pretty variable. Most of the video aspects are helpful, a few visually stunning. But in an apparent attempt to stamp the course as a leading edge presentation, the audio is frankly annoying. I thought that there was some feedback the first few times in the very first lecture, that a visual cue supporting a statement flashed on the screen. Did the professor really speak in front of a studio monitor and worse yet did post-production editing not catch it? Sadly no, the post-production choices of audio cues supporting the visuals were just annoying ones. Several reviewers have commented on misstatements, or a lack of understating about RNA and amino acids by Professor Close. I fault the TC more than the Professor, as they really should have picked up on the errors as a part of their quality control (of course the Professor could have had a knowledgeable colleague provide advice and do some fact checking). Better yet, this course would be an ideal vehicle for a team teaching approach. Adding an astro-biologist to present a few lectures on her area of expertise. In spite of the flaws, there is a lot her to like and learn about. Highly recommended, but it could have been so much better.
Date published: 2019-12-15
Rated 4 out of 5 by from Extremely interesting, but to much detail with chemistry, neurons, protons, etc.
Date published: 2019-10-18
Rated 2 out of 5 by from Could have been so much better This is the first Great Course I've taken and been very disappointed in. Every popup text on the screen is accompanied by a feedback noise - hard to tell if it was intentional or an oversight. Either way, not good. The lecturer uses the word "actually" so often I wanted to scream - sometimes in 4 or 5 sentences in a row, and occasionally more than once in a sentence.
Date published: 2019-09-10
Rated 5 out of 5 by from Interesting information Bought this as a gift and they are thrilled with it
Date published: 2019-05-14
Rated 5 out of 5 by from Amazing Astrobiology Course I took Professor Close's class and I had to commend his work on this course. The course is rich with content but still easily to digest and get a handle on. The lectures build upon themselves extremely well and it is clear that Professor Close cares about this lecture and has a lot invested into it. The love behind this course was apparent. I highly recommend this course to anyone interested in Astrobiology or Astronomy as a whole.
Date published: 2019-03-25
Rated 5 out of 5 by from One of my favourite "Great Courses" -- thrilling ! Yes, Professor Laird Close over-uses the word "actually". He also gives long pauses frequently: I wondered whether he was doing that intentionally to facilitate edits or inserts that might have to be made when he reviewed playback. Anyway, those tics didn't throw me; I found his style engaging, easy to follow, and very clear. It was a major plus to see a lecturer so obviously in love with his discipline, and eager to share his knowledge. The content of Dr. Close's course is brilliant: he creates a compelling and deeply fascinating story in a friendly but authoritative manner. His 24 lectures flow smoothly through an ideal progression, holding interest throughout. The liberal use of clear, strong graphics and video clips adds enormously to this winning, handsome course. I DISliked the various sound effects, though: the whooshing, dings, pipping and other odd sounds which were introduced presumably to emphasis points. One noise made me think my house, car or smoke alarm had gone off! This is my 200th review, and I'm privileged to mark the fact with this outstanding, engrossing course that starts by considering whether we are alone in the universe. In 1990 I met Dr. Isaac Asimov (he of the famous quote our lecturer refers to); two years later Dr. Asimov passed to eternity and now knows all the answers. For all of us on the planet, this course has to be a high point in the explanation of the formation of the universe, the birth of our "Goldilocks" planet, and the scientific quest for life elsewhere, as we journey into the world of ASTRO-BIOLOGY, searching for a planet that we might populate one day, even outside our solar system. Dr. Close's comparisons of Earth and our other solar system planets are superb, even exciting, I'd say. The lectures on extraterrestrial intelligent life, SETI, fossilized life from Mars, the Fermi paradox, and space travel - a reality check, are truly highlights. "Life in Our Universe" has immediate appeal to people with an enquiring scientific bent, particularly those with an interest in astronomy and life forms (c'est moi!); I strongly recommend this course to EVERYONE. It's 5-star all-round, one of my top choices from my 200+ Great Courses.
Date published: 2019-01-20
Rated 4 out of 5 by from Overall Good Overall, this is a very good class. The professor is excellent and is a very good communicator. I docked it one star because I feel like the class should have spent a little more time on astro-biology and a little less on our own planet. While I wish the time had been allocated a little differently, this is still well-worth watching.
Date published: 2018-09-04
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