Our observable universe shines with the light of hundreds of billions of galaxies, each with hundreds of billions of stars, vast clouds of gas and dust, nebula cast off in explosions—a zoo of luminous objects. And while that might sound like a lot of stuff, everything we have ever seen constitutes less than 5% of what’s out there. Nearly 25% of the universe’s content hides in an unknown form: dark matter. Despite decades of effort to detect dark matter, the substance eludes us. 

Director of Sciences Janna Levin invites physicists Elena Aprile of Columbia and Peter Fisher of MIT to ask if we truly should look for a new fundamental constituent of nature, or could dark matter actually be microscopic black holes? 

 brings together two scientists in conversation to explore unsolved quandaries. The focus is on ideas and the unknown, the precipice between where we are now and where we imagine the future will bring us.

In Scientific Controversies, hosted by our own Janna Levin, we tackle complex, conceptual, occasionally amorphous topics like animal consciousness and string theory. These rich, hour-long conversations take place in person at Pioneer Works, and feature big thinkers exchanging on big questions. To watch is a feast. “5 Takeaways” is a snack, an amuse-bouche for the mind. Because comprehension sometimes demands—or, at the very least, appreciates—distillation, and the internet loves a listicle. Below, for the benefit of lay science enthusiasts, contributor Anil Ananthaswamy serves up key takeaways from two conversations: one on 

, with guests Elena Aprile and Peter Fisher, and another on 

, with guests Rachel Rosen and Pedro Ferreira.

The universe has a dark sector. What is it?

It’s easier to start with what it is not. It’s not normal matter, which is everything that’s familiar: we and all life on Earth, the solar system, the Milky Way, the hundreds of billions of stars in our galaxy, the hundreds of billions of other galaxies in the universe, and the gas and dust strewn across intra-galactic and intergalactic space, all of it, down to the last elementary particle. This normal stuff makes up about five percent of the universe. The other 95 percent comprises the dark sector, named so partly because we don’t know its exact nature and partly because it doesn’t interact with light—which technically makes it invisible, not dark. The dark sector has two major components: dark energy and dark matter.

Why do we think there’s dark matter out there?

Astronomers have known since the late 1930s that something was amiss about the speeds at which galaxies move around in clusters, or the speeds at which stars and gases rotate about the center of a galaxy. Given the gravity of the discernible, luminous matter, the cosmic objects should be moving much slower than they are. By 1970, astronomer Vera Rubin had accurately measured such anomalous speeds in the nearby Andromeda galaxy. Her observations suggested that the gravity of an unseen mass was holding the galaxy together, preventing it from flying apart. This unseen mass has been termed dark matter. It doesn’t interact electromagnetically with normal matter, meaning it doesn’t emit nor engage with light. Multiple methods of estimating the amount of dark matter show that it makes up about 27 percent of the universe.

We don’t know. Astrophysicists once thought that dark matter could be non-luminous normal matter that’s hard to see. These would include: black holes; or neutron stars, which are the collapsed cores of supergiant stars; or brown dwarfs, which are small stars that cannot sustain the nuclear fusion needed to emit stellar light. These are collectively called massive astrophysical compact halo objects (MACHOs). Astronomical surveys, however, failed to find anywhere near enough MACHOs for them to be dark matter. Now, physicists, for theoretically plausible reasons, think dark matter is most likely made of particles known as weakly interacting massive particles (WIMPs), which would interact with normal matter only via the weak nuclear force and gravity. Efforts to create such particles at the Large Hadron Collider (LHC) at CERN near Geneva, Switzerland, have failed. It’s possible that their mass is beyond the reach of the LHC, and creating them would require more powerful particle smashers. Also, efforts to detect potential collisions of dark matter particles with nuclei of normal matter using ultra-sensitive detectors housed in deep underground mines have also failed. But the circumstantial evidence that dark matter exists is so strong that cosmologists continue to look for any clues as to what it might be.

If dark matter poses problems, dark energy compounds them. Through the 1980s and ’90s, cosmologists studying the expansion of the universe were expecting to find that spacetime had been steadily expanding for about ten billion years after the big bang, but this expansion would eventually have been reined in by the gravity of all the matter in the universe. But instead of slowing down, the universe’s expansion seems to have started accelerating about four to five billion years ago. Mostly, physicists attribute this to the inherent energy of spacetime, and call it dark energy. As the universe expanded, the amount of overall dark energy increased beyond a certain threshold, causing spacetime to blow apart—in a manner of speaking. Plug in the right amount of dark energy and dark matter into Einstein’s equations of general relativity and you can accurately model the universe’s observed initial unhurried expansion and then its recent acceleration. In today’s universe, dark energy makes up about 68 percent of the cosmos.

For starters, dark energy seems to have just the right value, in terms of the amount of energy per unit volume of space. Had it been less, the universe would have long since collapsed due to the gravity of matter; any greater and the universe would have blown apart before the stars and galaxies and planets could form, let alone intelligent planetary life pondering the mysteries of the cosmos. Physicists struggle to explain why dark energy has the value it does. It frustrates them that they cannot derive it from first principles. Also, quantum physics says that the emptiness of spacetime is not really empty: it’s a froth of virtual particles that constantly appear and disappear; this process gives spacetime an energy that’s about 120 orders of magnitude (=10

, or a trillion raised to the tenth power) greater than the observed value of dark energy. Something isn’t adding up. That’s why almost all the current and planned cosmological and astrophysical surveys of the cosmos are focused on deciphering the dark sector. ♦

Anil Ananthaswamy is an award-winning journalist and author of 

Dark Matter + Energy

5 Takeaways: Dark Matter + Energy

Janna Levin invites physicists Elena Aprile and Peter Fisher to ask if we truly should look for a new fundamental constituent of nature, or could dark matter actually be microscopic black holes?

Dark Matter

Are there Many Worlds? Does Time Exist? Are We Alone? Hosted by Director of Sciences Janna Levin, the Scientific Controversies series brings creative minds together to celebrate the passionate spirit of scientific curiosity. Previous guests include Nobel Laureate Frank Wilczek, geneticist George Church, and neuroscientist Christof Koch with subjects ranging from artificial intelligence and string theory, to dark matter, consciousness, and other unsolved scientific quandaries.

Humans aspire to build machines that think—but the algorithms that currently control and influence so much of contemporary life are far from thinking, sentient beings. And yet, these seemingly mindless formulas are embedded with the values of their creators. What are the implications of an AI evolved from greedy algorithms and poor intentions? PW Director of Sciences, Janna Levin, is joined by cognitive scientist Prof. Gary Marcus and mathematician Dr. Cathy O’Neil to learn more. The three ponder if our minds are machines—or if machines will soon acquire minds. ♦

PW Director of Sciences, Janna Levin, is joined by cognitive scientist Prof. Gary Marcus and mathematician Dr. Cathy O’Neil to ponder if our minds are machines—or if machines will soon acquire minds.

Minds and Machines

Traumatic events can overwhelm the brain, hijack the body, and distort one’s sense of self. Psychologists often address these responses through techniques that aim to integrate memories, promote personal insight, and deepen one’s understanding of the event. However, recent stress and trauma research has shown us that there are genetic, epigenetic, neurological, and hormonal mechanisms at play, and that understanding may not be enough to treat the symptoms. To learn more, Pioneer Works’ own Janna Levin sat down with Bessel van der Kolk—author of the New York Times best-selling book —and Rachel Yehuda—a pioneer in the epigenetics of trauma. Together, they considered the impact of trauma on our brains and bodies, pondering: Are we permanently damaged by trauma? Or is there resilience inherent in our very biology? ♦

Janna Levin sat down with Bessel van der Kolk—author of the New York Times best-selling book The Body Keeps the Score—and Rachel Yehuda—a pioneer in the epigenetics of trauma. Together, they considered the impact of trauma on our brains and bodies, pondering: Are we permanently damaged by trauma? Or is there resilience inherent in our very biology?

Does the Body Keep the Score? 

The Goddamn Particle—that is, the “Higgs Boson” that functions as the glue holding our material reality together—was finally discovered in July a dozen years ago. Leon Lederman famously referred to the Higgs as the “Goddamn Particle,” but his publisher resisted the moniker and pushed him to name his book “The God Particle” instead. As Lederman put it, ‘‘We managed to offend two groups, those that believed in god and those that didn’t. We were warmly received by those in the middle.’’ Watch the conversation between Janna Levin and physicists Sean Carroll and Melissa Franklin that details how the particle keeps our theories hanging together, and why a multi-billion dollar machine was built in Switzerland just to find it. ♦

brings together two scientists in conversation to explore unsolved quandaries. The focus is on ideas and the unknown, the precipice between where we are now and where we imagine the future will bring us.

The Goddamn Particle—that is, the “Higgs Boson” that functions as the glue holding our material reality together—was finally discovered in July a dozen years ago. Leon Lederman famously referred to the Higgs as the “Goddamn Particle,” but his publisher resisted the moniker and pushed him to name his book “The God Particle” instead. As Lederman put it, ‘‘We managed to offend two groups, those that believed in god and those that didn’t. We were warmly received by those in the middle.’’ Watch the conversation between Janna Levin and physicists Sean Carroll and Melissa Franklin that details how the particle keeps our theories hanging together, and why a multi-billion dollar machine was built in Switzerland just to find it. 

The Goddamn Particle

As a society, our dog-human bond suffers many contradictions. We sense their animalism, but we anthropomorphize them. We endow them with agency, but give them the legal status of property. We treasure them, but abandon them. We bond with them as individuals, but breed them to serve or please us. Yet dogs have minds of their own and a conscious awareness of the world we probably cannot ever fully comprehend.

Join our Director of Sciences, Janna Levin, as she hosts experts Brian Hare and Alexandra Horowitz in a discussion of the latest scientific research into dogs’ cognition, perception, and behavior—research that could profoundly impact our relationships to our own beloved canine companions. ♦

Janna Levin hosts experts Brian Hare and Alexandra Horowitz in a discussion of the latest scientific research into dogs’ cognition, perception, and behavior.

Dogs

We are biological machines, a naturally evolved intelligence bound in carbon and water. Our ambition to create an Artificial Intelligence in metal and silicon is probably unstoppable. We have already built machines vastly more capable at raw computations and data processing than our minds. But machines can’t recognize a face, reproduce, or learn unassisted. We can. Will machines ever exceed us in consciousness and willfulness? Would we be able to comprehend their minds and thoughts and motives if they do? Will they be malevolent? 

Director of Sciences Janna Levin invites Yann LeCun, Director of AI research at Facebook and NYU professor, and Max Tegmark, Director of the Future of Life Institute and MIT professor, to consider if humanity’s role in evolution will be to initiate the era of Artificial Intelligence at the peril of our own species. ♦

Janna Levin invites computer scientist Yann LeCun and physicist Max Tegmark to consider if humanity’s role in evolution will be to initiate the era of Artificial Intelligence at the peril of our own species. 

Artificial Intelligence

Every star, every pebble, every galaxy, every person, the oceans and the moon, the hundreds of billions of galaxies—every thing anyone anywhere has ever seen or will ever see in sum total amounts to less than 5% of the composition of the universe. Overwhelmingly, the universe is dominated by a form of invisible energy that permeates space—dark energy. We cannot see the energy although we live in an all-pervasive invisible dark sea. We do not know its origin or what it’s made of, if it will last forever, or evaporate in some far future. Though invisible, its dark presence is inferred as the unexpected source powering the ever-faster expansion of our universe. Dominant and everywhere, dark energy might be no more than the energy of nothing, an inescapable energy of empty spacetime. 

Director of Sciences Janna Levin invites cosmologist Pedro Ferreira and theoretical physicist Rachel Rosen to consider the most pressing question facing cosmology: What is dark energy? 

Janna Levin invites cosmologist Pedro Ferreira and theoretical physicist Rachel Rosen to consider the most pressing question facing cosmology: What is dark energy?

Dark Energy

“The enormous usefulness of mathematics in the natural sciences is something bordering on the mysterious… there is no rational explanation for it,” wrote Nobel Laureate Eugene Wigner. There are mathematical descriptions of natural phenomena on all scales: Fibonacci series in flowers, logarithmic spirals in snails, fractals in mountain ranges, parabolas in home runs, and pi in the spherical shape of stars, planets, and bubbles. But is math discovered in nature or is it invented by humans and imposed on an agnostic reality? Will mathematics always be able to unlock the mysteries of the universe, or will we come to an end of its utility?

Join our Director of Sciences Janna Levin as she hosts cognitive scientist Rafael Nuñez and physicist Max Tegmark in a conversation to challenge our beliefs on mathematics—discovered or invented—and to question if mathematics does in fact provide a fundamental, beautiful structure to the universe. ♦

Join Janna Levin as she hosts cognitive scientist Rafael Nuñez and physicist Max Tegmark in a conversation to challenge our beliefs on mathematics—discovered or invented?—and to question if mathematics does in fact provide a fundamental, beautiful structure to the universe.

Is Math Invented or Discovered?

Why do “I” experience life? Who is this “I”, the self? Is she real? Is consciousness possible without this sense of self? Is consciousness important, a lasting feature of the universe? Or is consciousness a failed evolutionary experiment? 

Conversations on consciousness can be laden with magical language, borderline mystical and meaningless. Yet biologists and neuroscientists seek a concrete, scientific understanding of it. Consciousness emerged from a continuum of increasingly complex biological systems. Some scientists hypothesize that living beings evolved a schema of self, the ability to direct attention, and then a self-aware consciousness. Humans place themselves at the end of this evolutionary progression, but is this misguided? Scientists struggle to see through their own mind’s tricks, striving for the rewards of greater understanding, and a more profound connection with nature. 

Pioneer Works Director of Sciences, Janna Levin, hosts neuroscientists Anil Seth and Joseph LeDoux to discuss consciousness, and how to see ourselves as less apart from, and more a part of, the rest of nature. 

Janna Levin hosts neuroscientists Anil Seth and Joseph LeDoux to discuss consciousness, and how to see ourselves as less apart from, and more a part of, the rest of nature.

Body, Brain, and Consciousness

Humanity glimpses a new era of space exploration with the first scientific images released from the James Webb Space Telescope, the most complex telescope ever built and the largest ever to be sent into space. Webb revealed to us the Southern Ring Nebula, a giant star at the end of its life in a glowing shell of hot matter. We witnessed four of the galaxies in Stephan’s Quintet engaged in an astronomically slow collision. We saw unprecedented detail of newborn stars emitting light and immersed in dust in the Carina Nebula. And Webb’s deep field image penetrated through the cosmic space dust that had obscured Hubble’s view to reveal even more galaxies, planets, and stars than previously imagined. This first suite of scientific images hints at a treasure of discoveries to come, discoveries that provoke us to contemplate humanity’s place in a vast and evolving universe.

In this new epic iteration of Scientific Controversies, Pioneer Works Director of Sciences, Professor Janna Levin, invites NASA’s Senior Project Scientist for the James Webb Space Telescope, Nobel Laureate John Mather, and renowned observational astronomer Wendy Freedman to discuss Webb’s very first glimpse of the universe and this new era in astronomy. ♦

Janna Levin invites NASA’s Senior Project Scientist for the James Webb Space Telescope, Nobel Laureate John Mather, and renowned observational astronomer Wendy Freedman to discuss Webb’s very first glimpse of the universe and this new era in astronomy.

James Webb Space Telescope

Scientific Controversies: James Webb Space Telescope

Since the emergence of life, genes have ruthlessly exploited organisms as vehicles for their own survival. The creature dies, but the genes survive. Slowly over generations, the gene is duplicated with the notably random mutation occasionally amplified by natural selection. However, with recent scientific advances, we’re now able to intentionally modify genes in the span of a few hours. No longer hapless carriers at the genome’s mercy, we can control which genes survive. We are now able to eliminate diseases in a stroke, create the ideal baby or even design a stronger smarter species. But at what cost to the future of humanity? 

Director of Sciences Janna Levin invites renowned geneticist George Church of Harvard and physician/biologist Siddhartha Mukherjee, winner of the Pulitzer Prize, to discuss the stunning implications and potential disasters of a brave new genetically modified world. 

Janna Levin invites renowned geneticist George Church of Harvard and physician/biologist Siddhartha Mukherjee, winner of the Pulitzer Prize, to discuss the stunning implications and potential disasters of a brave new genetically modified world.

Genetic Manipulation

Scientific Controversies: Genetic Manipulation

For billions of years, life on this planet waffled in oceans in the simplest single-celled incarnation. Today, all complex life forms, no matter how disparate they seem, share common features. Trees, humans, squid, and lettuce are related. It is not known how the simple single-celled organisms finally transitioned to a multi-celled organism that seems to be the singular, original source of all complex life on Earth. So how rare is the emergence of life on any planet, let alone complex life forms? 

We now estimate that there are tens of billions of planetary systems in our own galaxy and there are hundreds of billions of galaxies in the universe, each presumably stocked with the chemical blocks necessary for life. In the competition between such large numbers and such small numbers, which wins? Are we alone? Astrophysicist Janna Levin invites biochemist Nick Lane, author of The Vital Question, and astrobiologist Caleb Scharf, author of The Copernicus Complex, to discuss the origin of life on this planet, on other planets, and even in other universes. ♦

Astrophysicist Janna Levin invites biochemist Nick Lane and astrobiologist Caleb Scharf to discuss the origin of life on this planet, on other planets, and even in other universes.

Are We Alone

Are We Alone?

There may be billions of trillions of planets in the observable universe—possibly more planets than there are stars. These exoplanets range from giant storms of pure gas, like Jupiter, to rocky planets, like Earth, orbiting all manner of stars including dead collapsed neutron stars or even black holes. Their landscapes, weather, and astronomical calendars are stranger than science fiction could predict, as though the universe has experimented with every physically conceivable possibility. It seems unsustainable to imagine that only here on Earth has life emerged.

Scientific Controversies No. 22: Exoplanets

, Pioneer Works Director of Sciences, Prof. Janna Levin, invited NASA’s Kepler Mission Scientist Prof. Natalie Batalha and comparative exoplanetary scientist Prof. Rebecca Oppenheimer to discuss exoplanets, undiscovered life forms beyond our solar system, and if we will ever encounter kindred inhabitants of the Milky Way. 

Janna Levin invites NASA’s Kepler Mission Scientist, Natalie Batalha, and comparative exoplanetary scientist Rebecca Oppenheimer to discuss exoplanets, undiscovered life forms beyond our solar system, and if we will ever encounter kindred inhabitants of the Milky Way.

Exoplanets

Our perception of the material world is famously illusory. Nothing is solid. On closer inspection, all things resolve into a long list of fundamental particles, microscopic billiard balls subject to quantum forces. The list of known particles is disappointingly long – a cocktail with too many ingredients in a universe that promised elegance. String Theory attempts to restore elegance by unifying the multitude of ingredients into one. The essential idea: There are no particles, only vibrating loops of string. If true, then all the different quantum particles are just different harmonics played on fundamental strings. So is the entire universe a complex score played out on elementary strings? Or are we lost, distracted by the pursuit of an ideal beauty that the universe simply doesn’t possess? 

Is the entire universe a complex score played out on elementary strings? Janna Levin discusses with Nobel laureate and string theory pioneer David Gross and theoretical physicist Clifford Johnson.

String Theory

We often characterize animals as reflexive and unthinking, reacting almost mindlessly to instinct, when evidence to the contrary abounds across the animal kingdom. Consciousness did not materialize singularly and suddenly with the emergence of human beings—primates cooperate and console, as do elephants. Dolphins admire themselves in mirrors, apparently aware they are looking at their own reflection.

 co-editor-in-chief Janna Levin invites famed primatologist Frans de Waal and marine mammal scientist and cognitive psychologist Diana Reiss to Pioneer Works to learn more. The three explore and challenge our notions on animal consciousness, innate morality, and the imperative for compassion among species. ♦

Famed primatologist Frans de Waal and marine mammal scientist and cognitive psychologist Diana Reiss join Janna Levin in conversation to explore the possibilities of animal consciousness.

Animal Consciousness

Scientific Controversies: <br>Animal Consciousness

Black holes could have been relegated to mathematics and remained a physical absurdity. They were the outcome of a thought experiment, a fantastical imagining. Imagine matter crushed to a point. Don’t ask how. Just imagine that. But nature thought of a way to make them by killing off massive stars. These dead stars collapse under their own weight so catastrophically that even light gets dragged down the hole, casting a shadow on the sky. That shadow is the event horizon, left behind while the stellar material continues to fall to an unknown fate. For the first time in human history, we have seen a black hole. The image was captured by Event Horizon Telescope, a composite telescope the size of the whole Earth. Join Pioneer Works Director of Sciences and black-hole astrophysicist, Janna Levin, alongside Dr. Sheperd Doeleman, Director of the Event Horizon Telescope, and theoretical physicist Prof. Andrew Strominger to consider the staggering implications of event horizons from astrophysics to the theory of everything. 

Join black-hole astrophysicist, Janna Levin, alongside Dr. Sheperd Doeleman, Director of the Event Horizon Telescope, and theoretical physicist Andrew Strominger to consider the staggering implications of event horizons from astrophysics to the theory of everything.

Event Horizon

Black holes are gloriously weird. Formed as the death state of heavy stars, they can be as small as cities or as big as solar systems. Our own Milky Way galaxy is anchored at its center by a black hole four million times the mass of our sun but only 20 sun widths across. The rest of our galaxy could harbor billions of city-sized black holes. There are hundreds of billions of galaxies in the observable universe, each one replete with billions of stellar mass black holes and each one probably the home to one supermassive black hole. Beyond the oddity of black holes, they may play an essential role in sculpting galaxies and the universe on the largest scales. Black holes may have carved a world that we could live in. Director of Sciences Janna Levin invites Yale professor and astrophysicist Priyamvada Natarajan and the University of Arizona professor and astrophysicist Feryal Özel to question if our very existence is contingent on the shepherding role of black holes in the history of the cosmos. 

Janna Levin invites astrophysicists Priyamvada Natarajan and Feryal Özel to question if our very existence is contingent on the shepherding role of black holes in the history of the cosmos.

Black Holes

Scientists pursue blue-sky ideas uncontained. When Einstein proposed his most famous equation E=mc^2, he did not foresee its application to nuclear power. When Niels Bohr struggled with the new quantum theory, he never imagined its application to nuclear weaponry. After Lise Meitner contributed to the discovery of nuclear fission, she later said, “I will have nothing to do with a bomb!” Yet each of them, if inadvertently, had something to do with the bomb. The need to contain stockpiles of nuclear weapons and radioactive waste seems indisputable. But what about the imagination and ideas that lead to their creation, can they be contained? Janna Levin invites her guests to discuss the implications and viability of containment. ♦

Janna Levin invites historian Peter Galison and public policy expert Allison Macfarlane to discuss the implications and viability of containment.