Examining the Big Questions of Time

Make the time to really sit and think about what all these years, months, days, hours, minutes, seconds, and nanoseconds mean for us.
Examining the Big Questions of Time is rated 4.3 out of 5 by 26.
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Rated 5 out of 5 by from So interesting Very fascinating and deep with clear instructions, including all aspects of time.
Date published: 2021-09-12
Rated 2 out of 5 by from The course was not what I expected. I would not recommend this course to anyone.
Date published: 2021-08-27
Rated 3 out of 5 by from Time I liked the class, but the lecturer coveted a complicated subject too quickly for me. She spoke at such a rapid pace, it was difficult to take it all in
Date published: 2021-08-25
Rated 4 out of 5 by from Delivers As Advertised "I'm about to take you on a tour of some of the best articles the magazine [Scientific American] has published in the past two decades...they examined various aspects of temporality through the lens of physics, psychology, philosophy and cosmology, neuroscience, clockwork mechanics, and more." - Dr. Helmuth, introduction to course In the first two minutes of the introductory lecture, Dr. Helmuth lays out exactly what the course is going to cover. She then proceeds to deliver on that very syllabus. Each lecture is identified as corollary to one or more specific articles from the magazine. Generally, direct quotations from the articles and authors are included. The course presentation is clear and adequate. It suffers from an affliction common when the presenter is not the expert - a tendency to be overly technical in some points. This is not fatal. Its detractions are not from the content nor from the presenter. They are from the design of the video presentation, which is the fairly recent change from have a lecturer who stands and/or moves about, to a seated, stationary speaker, who appears against some sort of green-screen background. Literally, Great Courses has turned the lecturer into a talking head. Alternating two static views of that head is not dynamic, and adds little to the presentation. "The subject of time is one where the philosophical perspective is absolutely helpful, even to physicists like myself." - Sean Carroll, "Mysteries of Modern Physics: Time" I will take time to also recommend Prof Carroll's course, "Mysteries of Modern Physics: Time". He's an entertaining and thoughtful speaker. In particular, he closely examines the conundrum of "the arrow of time." Physics does not know about past, present, or future. So, how is it that we experience time as a one-way street? It's a good companion course for this one.
Date published: 2021-08-21
Rated 5 out of 5 by from I read SA mag frequently and was interested Although not a physics major, I thought I was pretty smart. This Time Course is pretty complex and I find myself lost at times. I really like the Professor and I know she was speaking English, so it must be me. I can tell you are dumbing it down to my level, which makes me feel even worse. I don't have any friends who would understand this any more than I do.
Date published: 2021-08-10
Rated 5 out of 5 by from Brilliant class with great information Love the course, so profound and excellent with clarity and depth
Date published: 2021-08-08
Rated 4 out of 5 by from Contains some difficult concepts Professor Helmuth does a good job of explaining some of the philosophical and scientific principles associated with time. But be forewarned. Some of her lectures are very difficult to understand. This should not be surprising, since time is one of the most esoteric concepts in all of physics.
Date published: 2021-07-29
Rated 5 out of 5 by from Time It was very interesting, though it was very technical at times.
Date published: 2021-06-23
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With the help of "Scientific American" magazine, dive into one of the biggest scientific explorations of the last few centuries to uncover the realities of time and how much-and how little-we truly understand about it.


Laura Helmuth
Laura Helmuth

Time defines us; it frames our experiences. We can’t live or understand our lives without it.


Scientific American

Laura Helmuth is the editor in chief of Scientific American. She earned a PhD in Cognitive Neuroscience from the University of California, Berkeley, and a graduate certificate in Science Communication from the University of California, Santa Cruz.

Laura has served as the health, science, and environment editor for The Washington Post; director of digital news for National Geographic Partners; science and health editor for Slate; science editor for Smithsonian Magazine; and editor for Science. She is currently on the advisory boards for Spectrum, an autism news website, and SciLine, an organization that helps journalists find the best scientific sources. She also serves on the board of directors for High Country News, a magazine that covers the American West. She is a member of the National Academies of Sciences, Engineering, and Medicine’s Standing Committee on Advancing Science Communication and was previously president of the National Association of Science Writers.

By This Expert

Examining the Big Questions of Time
Examining the Big Questions of Time


A Matter of Time

01: A Matter of Time

While most of us measure time in hours or days as we plan our activities, these units are not nearly small enough—nor large enough—for those who work at the edges of discovery. Explore how some scientists use attoseconds and others use billion-year increments to study the often baffling revelations of spacetime.

27 min
The Myth of the Beginning of Time

02: The Myth of the Beginning of Time

Just a few decades ago, scientists were absolute in their determination that time began with the Big Bang. But that’s all been turned on its head with the rise of string theory and other fascinating developments in theoretical physics. Learn how those advances brought the pre-Bang universe to the forefront of cosmology.

30 min
That Mysterious Flow

03: That Mysterious Flow

Right now, you are reading these words. True enough, right? But all that certainty erodes when we look at the concept of “now” through the lens of modern physics. Although we perceive “now” as being unique—our present moment always seeming to separate the knowable past from the unknowable future—you’ll learn why “now” slips from our grasp when we try to actually define it.

21 min
Is Time an Illusion?

04: Is Time an Illusion?

While we’ve all heard that time is money, the two terms might turn out to be more similar than we ever knew. Could time, like money, be just an invented convenience with no fundamental existence in the natural world? Discover the many ways in which philosophers have helped physicists grapple with this question—and the answers they’ve come to so far.

31 min
Time Travel and the Twin Paradox

05: Time Travel and the Twin Paradox

In a thought experiment called the twin paradox, Einstein illustrated that two observers moving at different speeds would experience different durations between the same two events. See how this time dilation has been proven and measured since Einstein’s life, and why your GPS wouldn’t work without accounting for it. Time travel, anyone?

23 min
A Chronicle of Timekeeping

06: A Chronicle of Timekeeping

From the ancient Egyptians to the 13th-century inventors of the mechanical clock to the atomic clocks of the last century, people keep striving to measure time more accurately. Understand why accuracy in timekeeping was important for the agriculturists of the Nile and why it still matters for those of us today who use navigation systems, cell phones, and electricity from the power grid.

29 min
Atomic Clocks

07: Atomic Clocks

Modern timekeeping has allowed us to measure differences in the passage of time as affected by motion and gravity to such a degree that relatively itself can now be measured in the lab. Learn about the development and precision of atomic clocks—and the myriad ways they benefit us—and about the optical clocks that can keep time to within one second in roughly 3.7 billion years.

27 min
Times of Our Lives

08: Times of Our Lives

Our circadian rhythm is hardwired into every cell in our bodies. Even under constant lighting, human cells in a petri dish will continue to follow 24-hour cycles of gene activity, hormone secretion, and energy production. Explore neurologists’ latest thinking about the brain’s internal timekeeping systems, and how those systems affect our health.

28 min
Remembering When

09: Remembering When

While our internal clocks regulate our physical processes, our mind has a clock of its own. Explore what scientists mean by “mind time,” and how we organize our thoughts about events in the passage of time. Uncover how mind time is linked to our ability to make and store memories, and reveal the interesting differences between anterograde and retrograde amnesia.

21 min
Inconstant Constants

10: Inconstant Constants

Almost all our scientific knowledge is possible because we rely on a few very basic constants—such as the velocity of light and the mass of the electron. Discover how string theory brings the possibility of a vast number of other worlds with different self-consistent laws and constants, and whether or not those worlds could possibly include biological entities like ourselves.

25 min
Atoms of Space and Time

11: Atoms of Space and Time

In the field of quantum mechanics, physicists have suggested for almost a century that light is made of energy packets that can behave like both a particle and a wave, a phenomenon known as photons. But could gravity also be made of discrete packets—gravitons? Explore the concept of loop quantum gravity and learn how physicists use spin networks to gain a deeper understanding of our universe.

29 min
Could Time End?

12: Could Time End?

As we experience life, time never ends. Even after death, our molecules will be recycled, and both time and matter will continue. But if time can slow down and speed up—as Einstein predicted, and later confirmed by observation—could it also end? Explore what the equations of modern physics tell us about the possibility of an end with no rebirth.

25 min