Videos

What do zebras have to do with the structure of the cosmos? Imagine a single zebra in your mind. With twitching ears, tufted hair, and a visual interference pattern wrapped over muscle and skin, the animal has its own contours, which are easy to make out up close. But get a large group of zebras together (a dazzle, by definition), and the individuals blend and meld into a seemingly homogeneous sea of heads, hoofs and stripes, especially when viewed from a great distance. The matter in the universe, it seems, dazzles in much the same way.

In this video, How the Big Bang Governs the Texture of Our Universe, we explore the concept of cosmic inhomogeneities—using zebras as an analogy for clumps of matter scattered throughout the universe. Animator Lottie Kingslake depicts these whimsical and familiar characters as they graze and form larger and larger groups similarly to how matter is pulled together in galaxies. We were inspired by the color palette of Marylyn Dintenfass’s paintings, which make up the backdrop in the live-action portion of the video.

This visual rendering takes up a fundamental question about the texture of space: Is it smooth or bumpy? The answer is that it is both. It is homogeneous, or smooth, when viewed from vast distances but inhomogeneous, or bumpy, at the scale of planets and galaxies. This difference in texture gives us hints about our universe’s earliest history and even lets us characterize how dark matter is distributed.

But what exactly does it mean for the universe to be textured as it is? Empty space is smooth because there is no matter to alter the equilibrium of the universe. Moments after the big bang, there was a period of inflation, in which the universe expanded exponentially. At this point, the universe was almost perfectly smooth—because although it was devoid of stars and galaxies (the first atoms did not form until about 380,000 years after the big bang), there were tiny quantum ripples in spacetime.

Over time, these tiny quantum fluctuations were amplified by gravity. Clumps and voids formed, creating a bumpy texture on relatively small scales. As gravity pulled the clumps together, they collapsed into themselves to form stars, planets and galaxies—and inhomogeneity gradually increased over cosmological time.

Our universe remains smooth, or homogeneous, over very long distances, where gravitational collapse does not hold sway. But if you zoom way out, all of the matter and energy in the cosmos appears evenly distributed.

That’s a little mental roughage to think about the next time you find yourself at the zoo.

Life’s up and downs may seem as inevitable as gravity, but somehow 2020 feels worse than usual. Just as a thought experiment, what if this year actually did get so weird that it even ushered in a change in how gravity affects our material universe?

In the video Did the Universe Have to Be the Way That It Is? we examine what our universe—and more specifically, our lives—might look like with some tweaks to the physics responsible for the world as we know it.

If gravity were just a little stronger in our own three-dimensional world, the curvature of spacetime would be greater, and matter could more easily collapse in on itself. This arrangement would make stars, galaxies and planets extremely diminutive, compared with the ones in our reality. Not only would we have less space on Earth, but our sun would deplete its nuclear fuel much more rapidly—meaning that evolution, and life itself, would be greatly curtailed.

If gravity were weaker, Earth would be gigantic, and it might be oddly shaped like some asteroids—or a potato. And rather than walking on the surface of our planet, we might find ourselves, say, jumping to grab a rebound in a basketball game, only to accidentally end up in the upper atmosphere or orbiting the globe as a tiny human space station.

What if we weren’t three-dimensional at all? (Imagine people as paper cutouts.) If we lived in two dimensions, gravity would act very differently. Although we would still have the spacetime curvature noted in Einstein’s general theory of relativity, such curvature would no longer produce gravitational forces. For this sort of flattened universe, we could instead have “scalar gravity,” in which Newton’s description of gravity would have been the final word, and black holes would be relegated to science fiction.

Thankfully, even though 2020 seems topsy-turvy, we still have gravity to keep us grounded.

Four hundred years ago Galileo Galilei’s scientific findings were rejected because they didn’t fit the prevailing beliefs of the time. His story is disturbingly relevant today. Astrophysicist and author Mario Livio and Scientific American editor Clara Moskowitz to discusses lessons from Galileo’s life for dealing with science deniers now, plus a historical detective story about Galileo’s famous motto, “And yet it moves.”

A new system called PiVR creates working artificial environments for small animals such as zebra fish larvae and fruit flies. Developers say the system’s affordability could help expand research into animal behavior. 

Over the past few months, the phrase “social distancing” has entered our lexicon. Many of us have found ourselves separated from family and friends—or at least from our normal social lives. As humans grapple with pandemic-induced isolation, science is starting to offer insight into what may be happening in our brains when our social contact with others is dramatically reduced.

That insight happens to come from a place with more penguins than people.

Tim Heitland of the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research in Germany spent 14 months in Antarctica between 2016 and 2018. When he returned, daily life felt overwhelming—everything from the colors and vegetation to all the other people. Part of the shock may have come from returning with a different brain than the one he left with.

While the members of Heitland’s crew conducted research on the earth’s iciest continent, they themselves were also being studied by researchers interested in how extreme work environments trigger neurological changes. The investigation showed that most of the people in Heitland’s team lost volume in parts of their hippocampus, a brain region involved in spatial navigation, learning and emotional processing. The phenomenon is similar to what scientists believe happens to prisoners in solitary confinement, where social isolation and sensory deprivation can lead to post-traumatic stress disorder.

This research appears particularly relevant now, when vast numbers of people are spending more and more time alone. Some scientists hope the work will lead to interventions that counteract the damage of isolation before it causes long-term problems.

Artificial intelligence still needs to bridge the “sim-to-real” gap. Deep-learning techniques that are all the rage in AI log superlative performances in mastering cerebral games, including chess and Go, both of which can be played on a computer. But translating simulations to the physical world remains a bigger challenge.

A robot named Curly that uses “deep reinforcement learning”—making improvements as it corrects its own errors—came out on top in three of four games against top-ranked human opponents from South Korean teams thatincluded a women’s team and a reserve squad for the national wheelchair team. (No brooms were used).

One crucial finding was that the AI system demonstrated its ability to adapt to changing ice conditions. “These results indicate that the gap between physics-based simulators and the real world can be narrowed,” the joint South Korean-German research team wrote in Science Robotics on September 23. 

Nikon’s Small World in Motion competition captures creatures and forces that are invisible to the naked eye.

How does SARS-CoV-2 sneak into our body? What can our immune system do and how can the virus sometimes defeat it? How do the leading drug and vaccine candidates work? Will the virus plague us forever? Scientific American presents a conversation about these burning questions with Britt Glaunsinger, a virologist at the University of California, Berkeley, and the Howard Hughes Medical Institute who is a specialist in viral infection.

Monterey Canyon has come into spectacular view after a decade and a half of effort

How massive can black holes become? How do astronomers typically observe them? How do they die? Scientific American presents a conversation about these mysterious cosmic phenomena with Yale University astrophysicist Priyamvada Natarajan.

The COVID-19 pandemic has become the worst public-health crisis in a century. More than 500,000 people have died worldwide. It has also catalysed a research revolution, as scientists, doctors and other scholars have worked at breakneck speed to understand COVID-19 and the virus that causes it: SARS-CoV-2. Nature runs through some of the key questions that researchers still don’t have answers to.

A new video re-creates a history that never happened, showing the power of AI-generated media