Life in Our Universe

Peer into the exciting new field of astrobiology and learn what science knows about one of the most fundamental questions of all time: Is there life elsewhere in the universe?
Life in Our Universe is rated 4.1 out of 5 by 48.
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Rated 5 out of 5 by from Very Good Series of Lectures - Thought Provoking This series exceeded my expectations. I was expecting a look outward at our universe and a lot of speculation and conjecture regarding the probability of life elsewhere. However, these lectures spend a lot of time looking at how, when and why life developed as it did here on Earth, what key conditions contributed to that life, and then begins to expand outward from Earth, searching for planets/other places with some of the same contributing key conditions. It also looks at how would we ever know other life existed elsewhere outside of our solar system, might it be 'intelligent', where might it be in relationship to our technological position, and many other interesting, thought provoking topics. Prior to this series, I looked at the shear immenseness of our universe and concluded that life must be fairly common throughout. After this series, I feel that Earth is a bit more 'special' than I previously had and that a lot of things had to go just right for us to be here at this point in time, recognizing that we were not able to be here billions of years in the past or billions of years in the future. Gives one a lot to think about. Could do without the plug for climate change concerns. In the scope of this series, minus and plus many billions of years, our climate has always been changing and will continue to do so, up until the time the sun becomes a red dwarf and cooks/devours the earth.
Date published: 2021-09-22
Rated 5 out of 5 by from Amazing course. This has been a great course. The lecturer was enjoyable, and his demos and little movies were fun. However, there were weird sound effects and the lecturer took long pauses and used -ly words too much.This has been one of my favorite courses so far.
Date published: 2021-03-31
Rated 5 out of 5 by from Brilliant Lectures Professor Close’s interesting and well-organized presentations, along with all the excellent visual aids, really hit the mark and I marvel at the wide range of topics that he was able to cover in those twenty-four segments. I learned a great many things that I did not know before and recaptured some of the sense of wonder and delight that I felt as a child when I first discovered astronomy.
Date published: 2021-03-11
Rated 2 out of 5 by from Wrong Title The information presented in this course is correct in-line with our present day knowledge. I can't fault it for that, I did think it was going to focus more beyond the earth and solar system than it did. It mentioned SETI then as far as extra-terrestrial life goes that's it really. Techniques used to search for ET the message Dr Close gives is why bother and we're doing it wrong. Communication with aliens much too hard, this is the most pessimistic course I've ever had from TGC; I'm not sure what was the real objective of this course is? Long term the message was we're doomed. A very disappointing course in general. Dr Close rings the alarm bell that we've only got a billion years then we're doomed. I'm more optimistic, lets face it we've managed to do an awful lot in the last two hundred years. What will we achieve in the next two hundred. We will do great things. Will we be able to exceed C? No, the physics contradicts this; will we explore the universe almost certainly. No I don't recommend this course, at best its a review of evolving life on earth nothing is truly discussed on what life forms we might encounter outside the solar system beyond it will be carbon based. A very disappointing course.
Date published: 2020-12-02
Rated 5 out of 5 by from Amazing. He goes into detail on everything. His only fault is he takes long pauses without reason.
Date published: 2020-11-09
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
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Are we alone in the universe? Or does the cosmos pulse with diverse life forms? 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 stunningly visual lectures offer an unparalleled look at the most intriguing discoveries coming from the new field of astrobiology, as well as the mysteries that remain. 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."


Laird Close
Laird Close

We are wonderers and explorers by nature-and we are just starting to set our sights on the stars, setting the stage for mankind's biggest adventure yet!


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 and mentor by his university, and in 2004, he was honored with a prestigious National Science Foundation CAREER Award, which is awarded to the top few percent of young science professors in America. He has also won major awards from the NSF's Major Research Instrumentation, Advanced Technologies, and Instrumentations program, and its Astronomy and Astrophysics program. Dr. Close has additionally won support from numerous NASA Origins of Solar Systems grants and is a member of NASA's astrobiology institute. While a researcher at the University of Hawaii, he discovered the first moon around an asteroid with a full orbit. Serving as Deputy Director for Adaptive Optics at the European Southern Observatory in 1998, he was the first instrument scientist for the most successful adaptive optics camera in the Southern Hemisphere. As a leader in brown dwarf and extrasolar planet high-contrast imaging astrophysics, he has invented and helped develop several cameras for the world's largest telescopes. Professor Close is the principal scientist of the 6.5m Magellan Adaptive Optics extrasolar planet imager, located in the high Atacama Desert of Chile.

By This Professor

Life in Our Universe
Life in Our Universe


Is There Life Elsewhere in Our Universe?

01: 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.

30 min
Bang! A Universe Built for Life

02: 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.

29 min
A Star Is Born-Forming the Solar System

03: 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.

30 min
The Early Earth and Its Moon

04: 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.

31 min
Impacts-Bringers of Death ... or Life?

05: 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.

29 min
Evidence of the First Life on Earth

06: 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.

31 min
Common Themes for All Life on Earth

07: 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.

30 min
Origin of Terrestrial Life

08: 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 geneti...

30 min
Astrobiology-Life beyond Earth

09: 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.

27 min
Has Mars Always Been Dead?

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.

28 min
Evidence for Fossilized Life from Mars

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.

28 min
Could Life Ever Have Existed on Venus?

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.

31 min
Liquid Assets-The Moons of Jupiter

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.

31 min
Liquid on Titan and Enceladus

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.

32 min
Discovery of Extrasolar Planets

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.

29 min
The Kepler Spacecraft's Planets

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.

30 min
A Tour of Exotic Alien Solar Systems

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.

31 min
Extraterrestrial Intelligent Life

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.

29 min
SETI-The Search for Intelligent Life

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 enormo...

31 min
The Fermi Paradox-Where Is Everyone?

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.

31 min
Space Travel-A Reality Check

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.

32 min
Terraforming a Planet

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.

30 min
The Future of Terrestrial Life

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.

32 min
The Search for Another Earth

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.

36 min