Twitter: @StartsWithABang (followed by 457 accounts on physicist, mathematician, and astronomer lists)
2015 to present
Average episode: 56 minutes
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Categories: Astronomy • Monologue (Non-Course)
Podcaster's summary: Podcast by Ethan Siegel
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|2022-Jun-12 • 100 minutes|
Starts With A Bang #82 - JWST And Infrared Astronomy
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 ...
|2022-May-08 • 93 minutes|
Starts With A Bang podcast #81 - The Local Bubble
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...
|2022-Apr-09 • 100 minutes|
Starts With A Bang #80 - The Cosmos, James Webb, and Beyond
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. Fo...
|2022-Mar-19 • 98 minutes|
Starts With A Bang #79 - The Far Infrared Universe
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 se...
|2022-Feb-06 • 92 minutes|
Starts With A Bang #78 - From Failed Stars To SETI
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 civil...
|2022-Jan-09 • 94 minutes|
Starts With A Bang #77 - Stellar Destruction
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 i...
|2021-Dec-18 • 91 minutes|
Starts With A Bang #76 - Supermassive Black Holes
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-r...
|2021-Nov-06 • 93 minutes|
Starts With A Bang #75 - Instruments And Mega - Cameras
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 e...
|2021-Oct-09 • 92 minutes|
Starts With A Bang #74 - Galaxy Clusters And Their Environments
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 envi...
|2021-Sep-20 • 113 minutes|
Starts With A Bang #73 - Ocean Worlds And So Much More
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 ...
|2021-Aug-06 • 93 minutes|
Starts With A Bang #72 - The Central Cores Of Galaxies
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 ...
|2021-Jul-10 • 79 minutes|
Starts With A Bang #71 - Rare Stars And Stargazers
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 s...
|2021-Jun-05 • 90 minutes|
Starts With A Bang #70 - The Accelerating Milky Way
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 tha...
|2021-May-10 • 91 minutes|
Starts With A Bang #69 - Machine Learning In Astronomy
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'...
|2021-Apr-10 • 92 minutes|
Starts With A Bang #68 - Pulsars, Polarization And More
Swarming through our own galaxy, we've detected quite a few bizarre objects: pulsars. These rapidly spinning neutron stars are only a few kilometers across, yet contain more mass than our entire Sun. They're denser than a uranium atom's nucleus, and some of them possess the strongest magnetic fields in the known Universe. The fastest-spinning one known rotates about its axis 766 times per second, and they can travel at up to ~65% the speed of light. And outside of the ones we've found, we fully expect there...
|2021-Mar-06 • 90 minutes|
Starts With A Bang #67 - Astroparticles And Dark Matter
If you look out at the Universe and measure all the matter out there, including stars, gas, dust, plasma, black holes, etc., it simply doesn't add up. You can't explain the gravitational effects you see with the known particles of the Standard Model alone. But even if you add in the one extra ingredient of cold, collisionless dark matter, it only fixes everything to a certain extent. In particular, the small-scale structures of the Universe, on the scales of individual galaxies and below, have a large misma...
|2021-Feb-14 • 99 minutes|
Starts With A Bang #66 - XENON And Astroparticle Physics
Have you ever wondered what it's like to work as a small (but vital) part of a large collaboration, where hundreds or even thousands of experimental scientists get together to produce an experiment far larger or more complex than any one person could oversee on their own? Have you ever wondered where the line is between physics and astronomy, and whether it even makes sense to have a line at all in the case of astroparticle physics? And have you ever wished that people would be more honest about the recent ...
|2021-Jan-11 • 83 minutes|
Starts With A Bang #65 - Ultracool Dwarfs
You might have thought that if we were going to find life anywhere in the Universe, our best bet would be to look at stars like our Sun, on account of the tremendous success of Earth. It's a good bet, for sure, but did you know that the Sun is brighter and more massive than 95% of stars in the Universe? And that down at the low-mass end of the spectrum, the most common type of objects out there are ultracool dwarfs: low-mass red dwarfs and even brown dwarfs? They have rocky planets around them and could be ...
|2020-Dec-13 • 114 minutes|
Starts With A Bang #64 - Galaxies Without Dark Matter
Over the past 2 years, an exciting development has finally arisen: scientists have measured a large number of small, diffuse galaxies exquisitely well, and have finally found their first candidate galaxies that appear to have no dark matter at all. Whereas large cosmic structures typically have dark matter-to-normal matter ratios of 5-to-1, smaller structures typically have higher ratios, as star formation will kick some of the normal matter out but leave the dark matter intact. However, there should be a s...
|2020-Nov-22 • 84 minutes|
Starts With A Bang #63 - Exoplanets, TESS, And Beyond
Over the past 30 years, we've gone from zero exoplanets to thousands. With each new generation of telescopes, observatories, and scientists, we build upon our previous finds to make enormous advances that go beyond what any one person could ever produce. The ESA's Gaia mission has surveyed more than a billion stars, identifying the closest ones that would make potentially great targets for NASA's James Webb Space Telescope, if they had potentially habitable planets around them. NASA's TESS is doing the prel...
|2020-Oct-12 • 84 minutes|
Starts With A Bang #62 - Black Holes And ALMA
It was only back in the early 2000s that scientists were struggling to identify and weigh the small number of supermassive black holes that we'd been able to identify in the known Universe, but the past 15-20 years have led to a revolution in what we know about them. We've identified tens of thousands of active galaxies, pinned down the masses of some of the closest ones to us through a variety of techniques, and even observed the event horizon of our first black hole directly. These powerful advances were...
|2020-Sep-25 • 111 minutes|
Starts With A Bang #61 - Astronomical Instruments And Injustices
When most of us think of astronomy, we think about two types of scientists: the observers who point their telescopes at the sky and collect data, and the theorists who put together the physical rules of the Universe to both make critical predictions for what those observational results ought to yield and to interpret the data that comes in. But in reality, there are other important types of astronomers that we don't talk about frequently: analysts who focus on dealing with these literally astronomical data ...
|2020-Aug-30 • 76 minutes|
Starts With A Bang #60 - The End Of The Dark Ages
When we look out at the Universe today, we see that it's full of stars and galaxies. And yet, we can only see those stars and galaxies because the space between those galaxies and ourselves doesn't block that starlight before it gets to our instruments, observatories, telescopes, and eyes. But early on, that's an enormous problem: there is light-blocking gas and dust, and the record-holder for most distant galaxy ever discovered is still not a pristine, first-generation galaxy at all. But there are new obs...
|2020-Aug-14 • 97 minutes|
Starts With A Bang #59 - Active Galaxies
When we look out at the galaxies in the Universe, almost all of them have supermassive black holes at their centers: millions or even many billions of times more massive than our Sun is. Most of the time, these black holes are relatively quiet, but every so often, a black hole can be spotted emitting enormous amounts of radiation over a large range of the electromagnetic spectrum. These "active galaxies" come in many different flavors, from blazars to AGNs to quasars and many others, but they're very closel...
|2020-Jul-17 • 80 minutes|
Starts With A Bang #58 - Gravitational Waves From Space
When it comes to gravitational waves, our terrestrial laser interferometers have provided us with unparalleled success in terms of direct detection. But they have some strong fundamental limits: their laser arms are short; their sensitivity is limited to low-mass, small-radius objects; the signals they detect last for mere seconds, at most. Most importantly, seismic noise, and even the fact that we live on a planet with tectonic plates, place restrictions on how sensitive we'll ever be able to get. But in ...
|2020-Jun-12 • 67 minutes|
Starts With A Bang #57 - The Universe's Newborn Stars
Even today, the Universe is forming enormous numbers of new stars: from various nebulae throughout our galaxy to mighty starburst galaxies where the entire galaxy is an enormous star-forming region. A decade ago, we were still trying to figure out how, when, and where stars formed throughout the Universe; today, we have that nailed down, but a whole suite of new questions and puzzles have arisen as a result of what we learned. On this edition of the Starts With A Bang podcast, I'm pleased to welcome Indian...
|2020-May-09 • 70 minutes|
Starts With A Bang #56 - Dark Matter Substructure
Dark matter is often thought of as the glue that holds the Universe together. With five times as much gravity due to this unseen form of matter as compared to normal, atom-based matter, it affects how galaxies and giant large-scale structures form in a tremendous, truly epic way. But depending on what the properties of dark matter actually are, we should get a very different Universe on smaller scales. Is dark matter cold? Warm? Hot? And does it interact with itself, or is it truly invisible? Thanks to a f...
|2020-Apr-10 • 70 minutes|
Starts With A Bang #55 - The Cataclysmic Deaths Of Stars
When you look up at the sky, most of the points of light we see appear to be fixed. On night-to-night timescales, the distant stars and galaxies, with the exception of a few notable variables, appear to be relatively unchanged. But every once in a while, a spectacular event will occur, giving off a transient signal that outshines a typical star's brightness by factors of many billions. These events fall into many classes: supernovae, gamma ray bursts, and even more exotic events, and part of the fun is unco...
|2020-Mar-04 • 71 minutes|
Starts With A Bang #54 - The Origin Of Stars
One of the great challenges for astronomy is to determine, in gory detail, how stars are formed from a mere cloud of molecular gas and dust. Although the general picture is simple, where gravitational collapse leads to protostars that ignite nuclear fusion in their cores, the actual environments where these stars are born have many competing factors at play. Gravitational collapse is only one of them, joined by thermal heating and radiative cooling, magnetic fields and hydrodynamics, as well as stellar wind...
|2020-Feb-07 • 64 minutes|
Starts With A Bang #53 - Exoplanets From Kepler To TESS And Beyond
How many planets are out there in the Universe? How many stars have planets, and what kinds of planets do stars of various types have? How close are we to doing direct imaging, finding whether some of our Earth-like planets are potentially habitable or even inhabited? Are Super-Earths a real thing, or are all of the ones larger than our world more Neptune-like than we care to admit? We've answered a whole slew of questions about exoplanets that we didn't even know to ask a decade or two ago, and there's so...
|2020-Jan-09 • 81 minutes|
Starts With A Bang #52 - The Thirty Meter Telescope
The history of astronomy is a history of receding horizons. As we improve our optics, our instruments, and our observing techniques, we can reveal progressively more of the Universe than we've ever seen before. As the 2020s dawn on us, we're preparing to jump from 10 meter-class observatories, which are presently the largest in ground-based optical telescopes, to 30 meter-class ones, with approximately thrice the resolution and ten times the light-gathering power. There's a tremendous suite of cosmic storie...
|2019-Dec-14 • 69 minutes|
Starts With A Bang #51 - Cosmology At The Edge Of Time
Have you ever wondered what the first moments of our Universe were like? Not just going back towards the hot Big Bang, but at the very first fractions of a second that come after, during, and even before the Big Bang occurs? It was my pleasure to get to speak to Dan Hooper, astrophysicist, professor, and author of the new book At The Edge Of Time, which is my favorite popular science book of 2019. (Pick up a copy here: https://amzn.to/2XReiGG) In this fascinating hour+ conversation, we cover topics like d...
|2019-Nov-14 • 78 minutes|
Starts With A Bang #50: The Hunt For Planet Nine And Beyond
What lies out there, in the outer Solar System, beyond the orbit of the last known planet? Up until 1992, you would have said Pluto and its moon (maybe "moons" if you were willing to speculate), but even the existence of the Kuiper belt was doubted by many. Of course, all of that changed with the discovery of many different objects, including the more-massive-than-Pluto world discovered in 2003: Eris. We quickly realized that Pluto was not unique, but one member of a distinct class of objects thoroughly dif...
|2019-Oct-12 • 93 minutes|
Starts With A Bang #49 - The LHC And The Future Of Physics
The Large Hadron Collider, located at CERN, is the most powerful particle accelerator and collider in human history, and the detectors that observe the collisional debris are the most sensitive and comprehensive ever constructed. With this powerful new tools, physicists discovered the Higgs boson earlier this decade, and continue to probe the frontiers of the known Universe. Currently undergoing upgrades, the LHC has only collected, to date, 2% of the eventual data it will wind up collecting. Meanwhile, ph...
|2019-Sep-12 • 73 minutes|
Starts With A Bang #48 - The Event Horizon Telescope
Earlier this year, 2019, the Event Horizon Telescope collaboration revealed the first image that directly showed the existence of an event horizon around a black hole. This image, constructed from many petabytes of data from telescopes observing the same target, simultaneously, from all across the Earth, provided a breathtaking confirmation of Einstein's relativity in a realm where it had never been tested before. But that's just one image of one black hole at one particular moment in time, and there's so m...
|2019-Aug-07 • 87 minutes|
Starts With A Bang #47 - Ice Giants At The Solar System's Edge
What do we really know, and what mysteries are left to solve, about the outer worlds of our Solar System, and about the gas giant and ice giant worlds found throughout the Universe? Remarkably, if you had asked this same question 30 years ago, we would have had a quaint story about how planets form and why our Solar System has the planets it does, and we assumed that these rules would be extended to all solar systems in the galaxy and Universe. But with the deluge of exoplanet data, accompanied by better ob...
|2019-Jul-19 • 91 minutes|
Starts With A Bang #46 - Experimental Particle Searches
We know that there's more to the Universe than we presently know. As successful as the Standard Model may be, it cannot describe everything we observe to be true about the Universe. Neutrinos oscillate from one flavor into another, and must have a non-zero mass, but we don't understand why or how. Dark matter has an overwhelming suite of astrophysical evidence that points towards its existence, but we have no direct evidence for the type of particle it might be. What do we do about these puzzles? We perfor...
|2019-Jun-14 • 75 minutes|
Starts With A Bang #45 - Beyond Earth 2.0
With all the planets out there in the galaxy and Universe, it's only a matter of time and data until we find another one with life on it. (Probably.) But while most of the searches have focused on finding the next Earth, sometimes called Earth 2.0, that's very likely an overly restrictive way to look for life. Biosignatures, or more conservatively, bio-hints, might not only be plentiful on worlds very different from our own, but around Solar Systems other than our own. Earth-like worlds, in fact, might not ...
|2019-May-03 • 62 minutes|
Starts With A Bang #44 - The Expanding Universe
One of the biggest conundrums in the Universe surrounds the question of how quickly the Universe is expanding. Questions like what is the Universe made of, how old is it, what is it's ultimate fate, etc., absolutely depend on this. For generations, we argued over the details of this, seeming to have finally reached a consensus in 2001 with the Hubble Key Project's results: 72 km/s/Mpc, with an uncertainty of about 10%. But the modern results, as of 2019, seem to depend on how you measure it. Some teams are ...
|2019-Apr-08 • 69 minutes|
Starts With A Bang #43 - Gravitational Microlensing
When we think about finding planets in the Universe, we typically look for ways to detect them as they orbit their parents stars, either affecting their star's position or velocity, or blocking or reflecting a certain portion of their light. But what about the planets that are too small to be detected that way? What about the planets whose effects are imperceptible? And what about the rogue planets: the ones that no longer (or perhaps never did) orbit a star of their own? Well, they're not doomed to be in...
|2019-Mar-25 • 71 minutes|
Starts With A Bang #42 - Black Holes And Gravitation
So, you want to know about black holes, including how we're seeing them, what happens when you fall into them, what our future plans for direct and indirect detection are, and how scientists are answering some of the biggest questions about them today? It's a fascinating story about some of the most mind-blowing objects in the Universe. Please welcome Assistant Professor of Astronomy and Physics at the University of Mississippi, Dr. Leo C. Stein, to the show, and enjoy a 1 hour+ conversation where we explo...
|2019-Feb-25 • 61 minutes|
Starts With A Bang #41 - Before The First Stars
After the Big Bang, it took only a few hundred thousand years for the Universe to form neutral atoms. But it took tens or even hundreds of millions of years for the first stars to turn on, and a whopping 550 million years for those neutral atoms to all become reionized by that starlight once again. Believe it or not, we can measure not only the starlight coming from the stars that do form through the now-infrared light they emit, but also the neutral atoms themselves through the power of 21-cm astronomy. I...
|2019-Jan-12 • 62 minutes|
Starts With A Bang #40 - Pristine Matter and Future Space Telescopes
One of the great goals in our study of the Universe is to see past the currently-known frontiers. That means going farther, to greater and greater distances. It means going fainter, to smaller and less-easy-to-see objects. It means going to earlier times and less-evolved conditions. And it means detecting more of the Universe than we've ever seen before. Our goal is the most ambitious one you can imagine: understanding what the Universe was like when it was born, how it grew to be the way it is today, and w...
|2018-Dec-20 • 58 minutes|
Starts With A Bang #39 - The Search For Extraterrestrial Intelligence
Is there intelligent life out there in the Universe beyond planet Earth? If so, are they technologically advances, can they hear us, and are they broadcasting in ways that we could possibly detect them? In the absence of their arrival on Earth, you might think that there's no surefire way to know. But the scientists working hard on SETI, the Search for ExtraTerrestrial Intelligence, sure are trying their best. By listening to the Universe at large (and our galaxy in particular), they're hoping to uncover t...
|2018-Nov-21 • 55 minutes|
Starts With A Bang #38 - Interstellar Interloper `Oumuamua
In 2017, the incredible happened: for the first time in history, we were able to identify an object passing through our Solar System that originated from outside of it! Interstellar interloper 'Oumuamua was originally designated as a comet, then as an asteroid, and then as a new class of object: one of interstellar origin. It's a fascinating object that's the first of its kind, and much has been said about its composition, properties, and possible nature. But, unfortunately, the most famous of those "nature...
|2018-Oct-23 • 72 minutes|
Starts With A Bang #37: The Outer Solar System
Our Solar System formed some 4.6 billion years ago from a molecular cloud that collapsed. Our proto-Sun formed along with a protoplanetary disk that eventually evolved into the Solar System we have today, complete with the inner, rocky planets, an asteroid belt, the gas giants and their moons and ringed systems, and then the outer Solar System. Those outer regions sure are interesting, and it's only over the past 3 decades we've really started to learn about them in earnest. I had the opportunity to speak ...
|2018-Sep-28 • 51 minutes|
Starts With A Bang #36: The Future Of Gravitational Wave Astronomy
I'm so pleased to welcome Dr. Erin MacDonald to the Starts With A Bang podcast, as we discuss the future of Gravitational Wave astronomy. From pulsars to merging black holes, to kilonovae to hopes of observing gravitational wave signatures from the earliest moments of the Universe, we cover a whole lot of astrophysics, cosmology, and experimental hopes for the near future in this burgeoning new field of astronomy. The future of gravitational wave science is so bright, even without the collection of any lig...
|2018-Aug-31 • 20 minutes|
Starts With A Bang #35 - Do We Live In A Multiverse
There's been a lot of speculative ideas put forth about the Multiverse, and I dare say that a great many of them are nothing more than wishful thinking. But that doesn't mean the Multiverse itself is ill-motivated at all. Rather, if you take two of our best theories that have been well-confirmed in a wide variety of different ways, you're going to find that you arrive at a bizarre but unavoidable picture: one of an inflating spacetime, eternal to the future, where regions that look like our Universe, comple...
|2018-Jul-27 • 25 minutes|
Starts With A Bang #34 - There Is No Big Bang Singularity
The Universe, today, is expanding and cooling, as the volume of the Universe increases while the number of particles within it remains constant. If you extrapolate forwards in time, the Universe gets sparser, less dense, and closer to being completely empty. But if you extrapolate back in time instead, the Universe gets hotter, denser, and smaller in volume. Eventually, if you didn't stop yourself, you'd go all the way back to a state of infinite density, where all the matter was packed into a single point:...
|2018-Jun-29 • 28 minutes|
Starts With A Bang #33 - The Limits Of Space
Have you ever wondered what's out there in the Universe, on the largest scales, beyond what we can even observe? Or what lies down below the tiniest distance scales we've ever probed? Is there a smallest fundamental length scale in the Universe, like the Planck scale, or can we go down even farther? Is space discrete or continuous? And is the Universe fundamentally blurred; can we even distinguish? Thinking about the limits of space, on both small and large scales, is a mind-bending game to play, but we're...
|2018-May-30 • 21 minutes|
Starts With A Bang #32 - Humanity's 3 Hopes For Alien Life
There are three very different ways humanity is searching for alien life beyond Earth. We can directly search the various planets and moons in our Solar System for past or present biological signatures simply by sending decontaminated probes, and looking for the evidence in situ. We can indirectly look at distant worlds around other stars, searching for the characteristic changes to the atmosphere and surface that life would bring. And, most optimistically, we can search for intelligent signatures created, ...
|2018-Apr-30 • 17 minutes|
Starts With A Bang #31 - The Most Important Equation In The Universe
There are some incredibly big questions that humanity has been asking about the Universe since we first began looking upwards: what is the Universe like, how did it get to be this way, where did it all come from, and what is its eventual fate? There were huge advances that were needed in order to answer these questions, such as understanding what the Universe was made of, how fast it was expanding, and what the laws governing it were. But once we know that, not only can we answer these questions, but we can...
|2018-Mar-29 • 22 minutes|
Starts With A Bang #30: Hawking's Greatest Discovery
In memory of Stephen Hawking's life, I've decided to share the physics behind his greatest discovery: Hawking radiation. For a long time, in the context of relativity, we thought that black holes were static, unchanging objects defined only by their mass, charge, and angular momentum. A number of developments led us to understand that black holes needed to have entropy, temperature, and therefore, they needed to radiate. But Hawking was the one to put that puzzle together, and describe the physics of the ra...
|2018-Feb-28 • 19 minutes|
Starts With A Bang #29 - What's At The Center Of A Black Hole
When you fall inside the event horizon of a black hole, there's no escaping, no matter what you do or how you accelerate. Even if you travel at the Universe's speed limit, the speed of light, there's simply no way to get any closer to the exit. Instead, scientists say, you have no choice but to fall inevitably towards the singularity at the center. But why must you arrive at a singularity? Couldn't you wind up at some degenerate object instead? We don't think so, and here's the science behind why. Find out...
|2018-Jan-31 • 19 minutes|
Starts With A Bang #028 - In God's Image
A simple, innocent question that I received had me thinking for days about how to answer it. The question? "If humans were made in God's image, whose image were aliens made in?" There's so much to say from a science perspective about how humans were made, and how aliens might be made, that I couldn't resist giving it my absolute best! Do you agree? Comment below!
|2017-Dec-29 • 22 minutes|
Starts With A Bang #27: The Biggest Question
Ever wonder about the biggest questions that there are? You know the ones I mean: about what is the Universe, where does it come from, and what is its fate? For millennia, these were questions for poets, philosophers, and theologians. Yet, despite all the "answers" that they offered, there was no way to test or verify whether they were correct. Enter science. After countless lifetimes struggling mightily with these, we have the answers, and they're spectacular. What do we know? How do we know it? And why ...
|2017-Dec-01 • 17 minutes|
Starts With A Bang #26: Traveling Backwards In Time
Ever dream of traveling back in time? According to all the laws of special relativity, all you can do is travel forwards through time, controlling your rate by controlling your motion through space. But in General Relativity, the curvature of spacetime allows you to play with those rules a little more flexibly. You can make it back in time, but you still can't kill your own grandpa before your parents were conceived. Find out why on this edition of the Starts With A Bang podcast! Video version (for the fi...
|2017-Oct-28 • 18 minutes|
Starts With A Bang #25 - Why Do We Need Quantum Gravity?
Our current best theories describing the Universe, general relativity for gravity, quantum field theory for electromagnetism and the nuclear forces, do a fantastic job independently and together. But there are fundamental questions that go unanswered if we take these as the final answers. What happens to the gravitational field of an electron passing through a double slit? What happens to the information on a black hole's surface when it decays? And what happens close by a gravitational singularity? Without...
|2017-Sep-29 • 18 minutes|
Starts With A Bang #24: The James Webb Space Telescope
Right around one year from today, the James Webb Space Telescope will launch to a position 1.5 million kilometers away from Earth, deploying into a quasi-stable orbit around the L2 Lagrange point. Its magnificent, 5-layer sunshield will unfold, allowing it to passively cool down to temperatures cold enough to turn nitrogen into a liquid. Beyond that, it will have on-board coolant taking it down to 7 Kelvin, allowing us to observe light that's 50 times as long as the wavelengths the human eye can see. The go...
|2017-Aug-30 • 27 minutes|
Starts With A Bang #23 - Experiencing A Total Solar Eclipse For The First Time
On August 21, 2017, a total solar eclipse occurred over the continental United States for the first time in nearly 39 years, when half the current US population wasn't even born. For many of us, it was our first opportunity to ever experience a sight like this for ourselves, and not only lived up to the hype, it was something that even a scientist couldn't fully anticipate. Here's a first-person account of what the experience was like, and how to enjoy it to the fullest, yourself, the next time one comes ar...
|2017-Jul-27 • 23 minutes|
Starts With A Bang #22 - The Science Of Solar Eclipses
On August 21, 2017, a coast-to-coast total eclipse across the United States will occur, the first one in 99 years. As the Moon's shadow hits the Earth and speeds across it, there's so much to see and enjoy, but only if you're prepared. What should you look for? Where should you go? How can you stay safe? And what's the science behind it? Come get the full story on the latest edition of the Starts With A Bang podcast! More information: https://www.forbes.com/sites/startswithabang/2017/07/27/the-sights-safe...
|2017-Jun-25 • 20 minutes|
Starts With A Bang #21: The Quantum Rule That Makes Existence Possible
At a fundamental level, everything we know of in this Universe is made of the same few fundamental particles: quarks, gluons, electrons and photons, which combine to give us atoms, which in turn make up all the molecules, cells, organs and living creatures inhabiting our world today. But how do we go from these tiny scales where everything looks so similar to the huge diversity of what exists at a larger, more macroscopic scale? The secret is encoded in a single quantum rule that governs how it all works: ...
|2017-May-28 • 20 minutes|
Starts With A Bang #20: Fate Of The Universe
Have you ever wondered how the Universe will end? In the far future, everything that we know, see, measure and perceive today will someday decay away, becoming something very different from what we know it as today. The Earth will cease to harbor life, the Sun will die, the galaxies will merge and recede, and eventually everything will fade to black. But beyond that, space itself will push everything apart, stellar remnants will get ejected, and even the most massive objects at all will decay into nothingne...
|2017-Apr-28 • 17 minutes|
Starts With A Bang #19: Is Time Travel Possible?
Is time travel possible? Of course it's inevitable in some sense, as we always move through the Universe at the "boring" rate of one second per second. But what about traveling into the future? If we go, can we ever come back? And what about back in time? Would it be possible to alter the past, or revisit a historical event as an observer? The mathematics of relativity opens the door to a lot of possibilities, but the physical Universe has a lot to say about it, too.
|2017-Mar-26 • 22 minutes|
Starts With A Bang #18: Why isn't Pluto a planet anymore?
In 1930, Clyde Tombaugh discovered Pluto: our Solar System's ninth planet. For over 60 years, the Plutonian system was the only one known beyond Neptune, and Pluto retained its planetary status for all that time despite its diminutive size. Yet an explosion of exoplanets and of other Trans-Neptunian Objects within our own Solar System beginning in the 1990s meant that we'd need to reconsider what it means to truly be a "planet". The debate still rages today, but astronomers agree: when it comes to the plane...
|2017-Feb-26 • 18 minutes|
Starts With A Bang #17 - When Was The First Star Born?
Our Universe was born pristine, with no stars, galaxies, molecules or even stable atoms, some 13.8 billion years ago. Yet today, we're filled with all the complex structure we see today, including with planets, organics and even something as complex and differentiated as a human being. So how did we get here? We had to form stars and galaxies, and evolve the Universe to a point where the raw ingredients to make us existed in great enough abundances and in the right conditions. There are some steps we're sti...
|2017-Jan-29 • 19 minutes|
Starts With A Bang #16: How fast is the Universe expanding?
The discovery almost 100 years ago that the Universe was expanding was a revolution for science, for cosmology and for our conception of existence. Hubble discovered what Einstein's couldn't imagine, and after that, the race was on to learn exactly what those observations meant for our cosmic origins. After decades of controversies, we now have a better picture of our Universe than ever before, yet questions remain. What will be the ultimate answer? Find out the possibilities, and what the limits of our kno...
|2016-Dec-25 • 16 minutes|
Starts With A Bang #15: Is our Universe the inside of a black hole?
Black holes are incredibly massive objects that are so dense that, from within a given region of space, nothing can escape, not even light. Yet it's arguable that from our point of view, nothing can escape our observable Universe. Moreover, even though our Universe is huge, it's also incredibly massive, and since it's expanding, it was denser and smaller in the past. Could our Universe be the inside of a black hole? And do we have evidence either supporting this or ruling it out? Find out on the latest epis...
|2016-Dec-01 • 19 minutes|
Starts With A Bang #14: Are Parallel Universes Real?
Ever since we first uncovered the quantum nature of our Universe, humanity has struggled to interpret it. Is there a wavefunction that collapses? Is it the quantum operators themselves that change? Does the end state evolve? Or are there an infinite number of parallel Universes that correspond to all the possible outcomes? This last possibility may actually be plausible, and this podcast is a deep dive into the adventure that ensues if they're real. But beware, there are a lot of assumptions needed to get t...
|2016-Oct-23 • 20 minutes|
Starts With A Bang #13: How Many Galaxies Are In The Universe?
Did you hear the news, that it isn't "billions and billions" anymore, but that there are TWO TRILLION (or 2,000,000,000,000) galaxies in the observable Universe? Come get the science behind this amazing story, including how we know, what it means and what we'll even have the potential to learn in the near future.
|2016-Sep-25 • 19 minutes|
Starts With A Bang #12: Exoplanets, beyond our Solar System and Proxima b
For thousands upon thousands of years, we didn't know whether the other stars in the Universe were even like our Sun, much less whether they had planets around them like we find in our Solar System. Over the past 25 years, however, that question has not only been answered, but we've discovered thousands of confirmed planets. Even more exciting, we've found that the star systems out there are similar to our own in some ways but tremendously different in others, and that there are already more than 20 rocky p...
|2016-Aug-28 • 19 minutes|
Starts With A Bang #11: Was The Big Bang The Beginning Of The Universe?
Our Universe has been expanding and evolving since the hot, dense, expanding state known as the Big Bang first came to be. But there was a "day without yesterday," where the Big Bang occurred at a moment in time! Was that the birth of space and time itself? Or was there a pre-existing state that came before and gave rise to the Big Bang? Come find out the evidence that's led us to our greatest conclusions about the very beginning of where everything came from!
|2016-Jul-27 • 18 minutes|
Starts With A Bang #10: The Last Star In The Universe
While there are presently more than ~10^23 stars in the Universe shining today, each one of them is fated to live only for a finite amount of time. While more and more will continue to form, we're already past the point of peak star formation in the Universe. How long will we have until, for the last time, the Universe's last star goes out? Find out on this edition of the Starts With A Bang podcast!
|2016-Jun-29 • 18 minutes|
Starts With A Bang #9: Interstellar Travel
Ever since humanity had the thought that the distant, twinkling stars might be Suns like our own, with their own planetary systems and chances at life, we've dreamed of extending humanity's reach to the galaxy and beyond. What are our actual chances of doing so, technologically, scientifically and practically? This podcast -- based on an exclusive interview with Larry Niven -- explores what's possible.
|2016-May-13 • 18 minutes|
Starts With A Bang #8: What is Dark Energy?
How will the Universe end? Will it recollapse in on itself, ending in a Big Crunch? Will it expand forever, ending in a Big Freeze? Or will it tear itself apart, ending in a Big Rip? With the discovery of dark energy, we finally think we know, but there's always more science to be done, more possibilities to consider, and new evidence to look for to help point the way.
|2016-Apr-22 • 24 minutes|
Starts With A Bang #7: Our Solar System's Planet Nine
Could there be a ninth planet in our Solar System, farther out than Neptune? Recent evidence points to a tantalizing possibliity, and searches are underway to look for it. Here's the science behind the full 'Planet Nine' story, in one amazing, easy-to-follow podcast!
|2016-Apr-03 • 18 minutes|
Starts With A Bang #6: The most distant galaxy in the Universe
The Hubble Space Telescope has just shattered the record for most distant galaxy in the Universe. How did we break this record, and what do we expect to find even farther back?
|2016-Feb-27 • 23 minutes|
Starts With A Bang #5: Gravitational Waves and LIGO
In February of 2016, less than six months after first becoming operational, LIGO (the laser interferometer gravitational wave observatory) announced the first-ever direct detection of gravitational waves. What are they? What does it mean? What did we learn? And what can we do with them now that we know they exist? All this and more on this month's Starts With A Bang podcast!
|2016-Feb-02 • 19 minutes|
Starts With A Bang #4: The story of Pluto and Charon
In 1930, Clyde Tombaugh serendipitously discovered Pluto: the first object in our Solar System out past Neptune. For 48 years, it was the only object known out there, until Charon -- its giant moon -- was discovered. But the 1990s brought with it a slew of Kuiper Belt objects, and in 2006, Pluto was officially demoted to a "dwarf planet." But also in 2006, NASA's New Horizons mission was launched: the first dedicated mission to the outer Solar System. In 2015, it flew by both Pluto and Charon, discovering t...
|2015-Dec-30 • 26 minutes|
Starts With A Bang #3: Why is there more matter than antimatter?
Everywhere we look in the Universe, we find that planets, stars, galaxies, and even the gas between them are all made of matter and not antimatter. Yet as far as we know, the laws of nature are symmetric between matter and antimatter: you can't create or destroy one without the other. So how did our Universe get to be the way it is? Come right up to the frontiers of our scientific knowledge and have a listen!
|2015-Nov-30 • 19 minutes|
Starts With A Bang #2 - Size Of The Universe
Although it's been only 13.8 billion years since the Big Bang, we can see objects as distant as 46.1 billion light years away. How is this possible? Ethan Siegel explains in the second Starts With A Bang podcast. Plus, how to see Comet Catalina in the December skies, and why it's on its way out of the Solar System forever. This podcast is free to download and distribute in perpetuity thanks to the support of our Patreon donors at www.patreon.com/startswithabang?ty=h
|2015-Oct-30 • 28 minutes|
Starts With A Bang #1 -- Water (and life?) on Mars
In the first inaugural Starts With A Bang podcast, astrophysicist Ethan Siegel discusses the latest evidence for water on Mars, what it means for Earth and potential life on the surface, as well as other topics. Guest (and Patreon supporter) Maciek makes an appearance, and we discuss the future of physics and speculate on what the next great advance might be. This podcast is free to download and distribute in perpetuity thanks to the support of our Patreon donors at https://www.patreon.com/startswithabang?...