Starts With A Bang Podcast

For a cosmologist like me, "cosmic dust" is a thing that's in the way, confounding our data about the pristine Universe, and it's a thing to be understood so that it can be properly subtracted out. But the old saying, that "one astronomer's noise is another astronomer's data," proves to be more true than ever with cosmic dust, as how it's produced, where it came from, and how it comes together to form planets, molecules, and eventually creatures like us, are some of the most essential elements necessary for us to exist within this Universe. In visible light, cosmic dust is normally just a starlight blocker, but in other wavelengths of light, its composition, distribution, density, grain size, polarization, and many other kinetic and thermal features can be revealed. Here to guide us through the ins-and-outs of cosmic dust, with a special view towards millimeter, submillimeter, and radio wavelengths, I'm so pleased to welcome PhD candidate Carla Arce-Tord to the show. Enjoy this far-ranging tour of cosmic dust

The supermassive black holes at the centers of galaxies is a tremendously interesting area of research, advancing rapidly over the past few years. While most of these observations focus on either high-energy or radio emissions from them, there's a recent push to see what these objects are doing in other wavelengths of light, as well as how they vary in time. Once, it was thought that supermassive black holes would become "activated" at a certain point in time, would remain on for hundreds of thousands or even millions of years, and would then turn-off. But our observations have shown us that there are remarkable variations in what types of light and energy these objects emit over time, and with new studies being conducted at the South Pole and other places studying the Universe in millimeter-wavelength light, we're about to get an unprecedented amount of high-quality data. Here to guide us through what we've learned so far about these active galaxies and where this research might take us in the future is Dr.

All throughout the Universe, we see stars and galaxies everywhere we look. But as we look to greater and greater distances, we're only seeing the light that's the easiest to see: the ones from the brightest, most visible objects. But the most numerous objects of all are exactly the opposite: less luminous, smaller, and lower in mass. How can we hope to find and catalogue them all if they're the hardest ones to find? The answer lies in measuring the closest stars to us. If we can measure the stars that persist in our own backyard, cataloguing them and taking as complete a census as possible, we can then combine what else we know about stars and starlight and the environments in which new stars form to reconstruct precisely what we believe is out there: not just here-and-now, but elsewhere and all throughout cosmic time. Here to bring us up to speed on how this attempt to catalogue and categorize the stars in the Universe, I'm so pleased to welcome PhD candidate at Georgia State University Eliot Vrijmoet to the

Although it seems like a long time ago, it was as recent as the early 1990s that we had no idea whether planets in the Universe were universal, common, uncommon, or even exceedingly rare. While certain data sets once seemed to indicate that practically every star in the Universe had planets around it, we now know that isn't true at all. Many stars, perhaps even most of them, have planets, but plenty of others don't. In addition, the number and types of planets that exist, including planets without parent stars at all, are still under investigation, and the field of planet formation has become extremely active. With new data coming in from infrared and radio observatories, including JWST and ALMA, we're learning so much about the planets that form in the Universe, including what conditions they form under and what the various important, dominant considerations are. Here as our latest guest on the Starts With A Bang podcast, to help us disentangle what's known from what remains a curiosity, is Dr. Kamber Schwar

From the earliest stages of the hot Big Bang up through and including the present day, one cosmic picture is sufficient to describe practically everything we observe: the Lambda-Cold Dark Matter (ΛCDM) cosmological model. With a mix of dark matter, dark energy, normal matter, photons, and neutrinos, we can not only model, but can simulate the Universe from the earliest times and the smallest scales up through to the present and the full scale of the observable Universe. In most cases, theory and observation match, and spectacularly so. But there are a few current points of tension: cosmological mysteries, that range from the expansion rate of the Universe to small-scale structure formation to the link between the pre-Big Bang Universe and our current dark-energy-caused accelerated expansion. Where are we, how far have we come, and how far do we still have to go? I'm so pleased to welcome Dr. Santiago Casas, who specializes in many of the same sub-areas of cosmological physics I specialized in about a decad

Since the advanced LIGO detectors first began operating in 2015, we've not only directly detected our first gravitational wave signals from merging objects in the Universe, we've observed close to 100 such systems that have emitted detectable gravitational wave signals. All of them to date, however, are the result of short-period, low-mass stellar remnants that have inspiraled and merged into one another. The most massive black holes, at least in gravitational waves, remain elusive. If all goes well, however, that won't be the case for long. At the centers of very massive galaxies, there's often not just one supermassive black holes, but multiples. Ultramassive binary black holes, in fact, send such energetic ripples through spacetime that they ought to distort, in measurable ways, the arriving radio signals from pulsars distributed all throughout the Milky Way. By monitoring these pulsars extensively through a series of timing arrays, we just might be able to extract information about the longest-wavelength

It's now been nearly a full six months since the JWST was launched, and we're on the cusp of getting our first science data and images back from some 1.5 million kilometers away. There are all sorts of things we're bound to learn, from discovering the farthest galaxies of all to examining details in faint, small objects to searching for black holes in dusty galaxies and a whole lot more. But what's perhaps most exciting are the things we're going to find that we aren't expecting, simply because we've never looked in this particular fashion before. I'm so pleased to welcome two guests to the show: Research Professors Dr. Stacey Alberts and Dr. Christina Williams both join me this month, and we have a far-ranging conversation about infrared astronomy and all that we're poised to learn from exploring the Universe in the infrared as never before. If you're already excited about JWST and what we're going to learn from it, wait until you listen to this episode! (Image: Although Spitzer (launched 2003) was earlier

When we look out at the Universe, what we see is typically what we think of: the points of light. Depending on the scales we're looking at, this can come in the form of stars, galaxies, or even clusters of galaxies, but it's almost always information that comes to us in some form of electromagnetic radiation, or light. But sometimes, light can be just as informative for what either isn't there or how it's been affected by the various media that it's passed through! In the case of our own cosmic backyard, a new study from earlier this year, 2022, revealed something spectacular and entirely unexpected: that the Sun sits at the center of a ~1000 light-year wide structure known as the Local Bubble, itself just about 15 million years old but containing all of the nearest young star clusters to us. In fact, the star Aldebaran, one of the brightest in the sky, helped "blow" this bubble in the interstellar medium! It's the very first episode of the Starts With A Bang podcast ever to feature multiple guests, and I'm

Have you ever wondered how it is that we know all we do about galaxies? How they formed, what they're made of, how we can be certain they contain dark matter, and how they grew up in the context of the expanding Universe? In any scientific discipline, we have the things we know and can be quite confident in, the things that we think we've figured out but more data is required to be certain, and the things that remain undecided given the current evidence: things over the horizon of the present frontiers. Fortunately, we have the ability to scrupulously identify which aspects of galaxy formation and evolution fall into each category, and to walk right up to the edge of our knowledge and peer over that ever-expanding horizon. Joining me for this episode of the Starts With A Bang podcast is scientist Arianna Long, Ph.D. candidate at the University of California at Irvine and soon-to-be Hubble Fellow at the University of Texas at Austin. With the advent of ALMA and the James Webb Space Telescope, in particular, w

Every time we've figured out a different way to look at the Universe, going beyond the capabilities of our own meagre senses, we've opened up an opportunity to learn something new about what's out there. Although optical astronomy and near-infrared astronomy are arguably the most popular ways to view the Universe, with James Webb soon to bring the mid-infrared Universe into view as never before, we shouldn't forget about the value of other, more distant wavelengths of light. One of the most fascinating sets of data that we can collect is in the far-infrared, where gas heated to just a few tens of Kelvin shines, but where much hotter, even ionized gas can emit very special hyperfine transitions. Mapping out these regions of space helps us understand what's going on beyond mere star-formation or other violent events, and a series of remarkably specific observational techinques are, quite arguably, how we're obtaining the most valuable information of all in this part of the electromagnetic spectrum. Joining t

When you start looking at the Universe, you realize that there are more signals out there than are simply generated by stars. On the one hand, you have astrophysical objects like gas, dust, plasma, as well as stellar corpses and their remnants. But there are also failed stars that didn't quite make it to the nuclear fusion stage that defines our Sun and the other stars like it: brown dwarfs. Beyond that, there may also be signatures of planets like Earth out there: planets inhabited by an intelligent civilization. It's of paramount importance, when asking the biggest questions, to make sure that we aren't fooling ourselves, but that's where projects like SETI and Breakthrough Listen come in: to help us extract legitimate science where "wishful thinking" has the potential to lead us in precisely the most dangerous direction: the possibility of fooling ourselves. I'm so pleased to welcome Ph.D. Candidate Macy Huston to the podcast, as we explore the less commonly seen side of the Universe: from exoplanets to

Some stars, as they go through their life cycles, will die of natural causes. They'll burn through their fuel until they can fuse elements no longer, and then will die, becoming a white dwarf below a certain mass threshold, or experiencing a core-collapse supernova that leaves behind a neutron star, a black hole, or perhaps something even more interesting above that mass threshold. But some stars, while just going about their lives, can suffer a wildly different fate: they can be murdered by other objects in the Universe. Stellar destruction can take many forms and can give off many different unique signals, and it's only by examining a wide range of the electromagnetic spectrum, as well as other types of sources, that we can decode what's actually going on across the Universe. I'm so pleased to welcome Dr. Yvette Cendes to the program, who specializes in radio astronomy and the behavior of exotic objects that change their behavior over time: transient signals. There's so much to explore and I hope you enjo

When it comes to the black holes that populate the Universe, they range from the very tiny, of only ~3 solar masses or so and with event horizons that span only a few kilometers, all the way up to the incredibly supermassive, many billions of times as massive as our Sun, with event horizons on the scale of the entire Solar System. These black holes are fascinating not only for how they form and exist, but how they impact and shape the entire galaxies that they inhabit. At all different wavelengths, from X-ray to radio, as well as in gravitational waves, we're only starting to uncover the previously elusive science about these cosmic behemoths, and while we're all the richer for it today, it's fascinating to consider what questions we'll be answering decades down the line, too. Come have a listen to all of these topics and much, much more as we go on a fascinating journey concerning supermassive black holes with Dr. Adi Foord of Stanford, and expose the mysteries of the largest single structures in the entire

You know how it works, right? Point your telescopes at the sky, collect the data, and then send it off to the scientists for analysis and to compare with the predictions of your theories. Only, if that's what you do, you'll miss a crucial first step: you have to handle your data correctly. That means understanding the nuances of your telescope, the sensitivities of your instruments and optics across different filters and wavelengths, and so many other considerations before that data you've collected could ever be responsibly used for any scientific purposes at all. But this is not a hopeless task; there are entire careers in telescope and instrument support sciences that, in many ways, are the unsung heroes of the entire enterprise of astronomy. In this edition of the Starts With A Bang podcast, I'm so pleased to get to bring Dr. Heather Fleweling onto the show, where she talks about her experience and expertise doing precisely this for observatories such as Pan-STARRS, which she helped build herself, to the

In the science of astronomy, it's important to see both the forest and the trees. Galaxy clusters, in many ways, serve as both. They're rich environments with stars, gas, dust, dark matter, black holes and more. The diversity of stars and stellar populations found within them, as well as found within galaxies of different shapes, sizes, and properties within those clusters, are part of a remarkable and coherent cosmic story. But sometimes the cosmic story can help us understand what's going on in these environments, the converse of the way we normally think about it: where we use the environment to learn about the universe. Come take a fascinating journey into these cosmic behemoths that are the gathering grounds for the greatest collections of large galaxies in the universe, and enjoy a delightful conversation with Gourav Khullar as we go along on this wild ride! (Image credit: ESA/Hubble and NASA, H. Ebling)

If you want to understand the origin of life in the Universe, you have three basic ways to do it. One is to search for intelligent aliens directly: through a program such as SETI. Another is to search for life in Solar Systems beyond our own: looking for bio-signatures, or perhaps bio-hints, on extraterrestrial worlds many light-years away. But within our own Solar System, there are a plethora of worlds, including the ice-and-liquid-rich bodies we have, that are fascinating candidates for life of non-Earth origin. There's so much to explore and so many different aspects of what's out there that I went into an incredibly far-ranging conversation with our podcast guest, planetary scientists and NExSS postdoc Dr. Jessica Noviello, that we wound up talking for nearly two full hours, and still couldn't cover everything we wanted to! Still, it was an amazing conversation for me and I hope it is for you, too. Enjoy it! (Image credit: NASA/JPL/Ted Stryk, of Europa with its uniquely curved stripes, for the Galileo

Practically every galaxy in the Universe has a supermassive black hole at their core. Ranging from millions to many billions of solar masses, these cosmic behemoths are capable of behaving as engines: accreting and accelerating matter to tremendous speeds and temperatures, where they emit enormous amounts of radiation. Galaxies can remain in this active state for hundreds of millions of years, where they appear to us as active galactic nuclei or quasars, depending on their specific properties. But why are some galaxies active while others aren't? How long will the active ones we see remain active, and will some of the inactive ones turn on? What about flares? As it turns out, there's a powerful connection between the surrounding galaxy, the processes occurring at the core, and the activity levels of the central black hole. Here to help us put it all together is Dr. Yashashree Jadhav, who takes us on a fascinating and far-ranging discussion about black holes, gas, stars, and much, much more! Enjoy it all on t

Like everything in the Universe, stars are born, they live a little while, and then they die. But despite their similarities in terms of where they come from and what they're made of, these objects can have an enormous variety of fates that they experience, and there are some fascinating intermediate and near-final states along the way. Beyond that, the unique stories of the people who made those key discoveries that have brought us to where we are can help us understand exactly how we pieced together the stellar picture of our Universe's history together. I'm so pleased to welcome Emily Levesque, professor at the University of Washington, author of The Last Stargazers, and enthusiastic lover of the Universe beyond planet Earth to the podcast. This ~80 minute episode was one of my favorites, and showcases Emily's knack for combining her vast knowledge of astronomy with her passion for sharing those stories with the entire world. Have a listen on the latest installment of the Starts With A Bang podcast! (Ima

When we think about the Universe as a whole, the accelerations that objects experience from our perspective are overwhelmingly due to the expansion of the Universe. Nearby, however, it's the local gravitational effects of nearby masses that dominate. Within our own Local Group, we've been able to discover that the Milky Way is not some quiet, massive spiral just going about its own business, but rather that it's being tugged in a variety of ways from the large masses around it, including a nearby galaxy that was only discovered in very recent years: Antlia 2. This is one of the most exciting detective stories we've gotten to uncover in recent years, as the resolution of this mystery showcases how improved, high-resolution data taken over long periods of time can enable us to witness galactic changes, directly, on the timescale of a single human lifetime. Here to walk us through what we know, how we know it, and what comes next is Prof. Sukanya Chakrabarti of the Rochester Institute of Technology, and I think

When you think about how astronomy works, you probably think about observers pointing telescopes at objects, collecting data about their properties, and then analyzing that data to determine what those objects are truly like, and to infer what they can teach or show us about the Universe. But that's a rather old-fashioned way of doing things: one that's contingent on there being enough astronomers to examine all of that data manually. What do we do in this new era of big data in astronomy, where there aren't enough astronomers on Earth to even look at all of the data by hand? The way we deal with it is fascinating, and involves a mix of statistics, classical analysis and categorization, and novel techniques like machine learning and simulating mock catalogues to "train" an artificial intelligence. Perhaps the most exciting aspect is how thoroughly the best of these applications continuously outperform, in both quality and speed, any of the manual techniques we've used previously. Here to walk us through this