Happy new year, everyone, and with a new year comes a spectacular new podcast! We normally cover an intricate and underappreciated aspect of astrophysics on the podcast, but I had the opportunity to bring on a true expert in the field of quantum computing and just couldn't pass it up.

You've likely heard a lot of noise about quantum computers and the benefits that they're poised to bring, with buzzwords like "P=NP," "quantum supremacy," and "quantum advantage" tossed around, but a lot of what you're likely to hear is hype, not actual science. Good thing I was able to get Dr. Riccardo Manenti as a guest for our podcast!

Riccardo is the author of a state-of-the-art textbook on quantum computers, has his PhD from Oxford in Quantum Computing, and has been working for Quantum Computing startup Rigetti for several years now. Join us as he helps demystify some of the recent progress and problems right here on the cutting edge of this promising new arena of physics, right here on the Starts With A Bang podcast!

(This illustration show's Rigetti's widely-available quantum computer, Novera, with 9 superconducting physical cubits within it. The great hope is that by scaling up to greater numbers of physical qubits, quantum advantage will be an achievable milestone in the relatively near future. Credit: Rigetti/Novera)

Starts With A Bang #101 - Quantum Computing

When we search for life in the Universe, it makes sense to look for planets that are similar to Earth. To most of us, those signatures would look the same as the ones we'd see if we viewed our planet today: blue oceans, green-and-brown continents, polar icecaps, wispy white clouds, an atmosphere dominated by nitrogen and oxygen, and even the modern signs of human activity, such as increasing greenhouse gas emissions, planet modification, and electromagnetic signatures that belie our presence.

But for most of our planet's history, Earth was just as "inhabited" as it is today, even though it looked very different. One fascinating period in Earth's history that lasted approximately 300 million years resulted in a planet that looked extremely different from modern Earth: a Snowball Earth period, where the entire surface, from the poles to the equator, was completely covered in snow and ice. This isn't just speculation, but is backed up by a remarkable, large suite of observational and geological evidence.

So what was Earth like during this period? How did it fall into this phase, how did it remain trapped in that state for so long, and how did it finally thaw again? To help explore this topic, I'm so pleased to welcome PhD candidate Alia Wofford to the program, who conducts intricate climate models of early Earth to try to reproduce those early conditions. From that work, we're learning about what we should be looking for when it comes to potentially inhabited exoplanets, because Earth has been inhabited for around 4 billion years, and wow, has its appearance changed over all that time. Have a listen and see for yourself!

(This illustration shows a frozen-over planet, but one that still possesses a significant liquid ocean beneath the surface ice. Many worlds in our Solar System may be described by this scenario at various points in cosmic history, including even planet Earth more than two billion years ago. Credit: Pablo Carlos Budassi/Wikimedia Commons)

Starts With A Bang #118 - Snowball Earth

Launched in May 2024, ESA’s Earth Explorer EarthCARE mission has already been delivering remarkable data. Its four instruments have brought us groundbreaking insights into clouds, aerosols and Earth’s energy balance. The mission is being featured in an immersive installation called Hakuryu, which is Japanese for White Dragon, at the Living Planet Symposium in Vienna and here’s the accompanying sonification of atmospheric data downloaded from the EarthCARE satellite.

EarthCARE data transformed into a dragon’s song for peace

Every day, the Sun sends out bursts of energetic electrons into space. As these electrons collide with other charged particles, they produce radio waves—captured by the Radio and Plasma Waves (RPW) instrument on ESA’s Solar Orbiter spacecraft.

This track is a sonification of one six-hour data segment from a five-year dataset compiled by a team at Radboud University and Paris Observatory. Each drop in pitch represents electrons travelling further from the Sun, where fewer particles are left to interact with—causing the radio frequency (and now sound) to drop.

Listen for the distinctive “pyoong” sounds—real solar radio bursts, each starting sharp and fading low. The data has been sped up for your ears; that dramatic burst at the centre? It lasted three hours in space.

Credit: ESA & NASA/Solar Orbiter/RPW, sonification by Katerina Pesini
Acknowledgements: Philippe Zarka (IDL script), Alan Loh (Python script), Dimosthenis Bitzilos (video editing support)

Sound of a Solar Storm: Radio Bursts from the Sun

Perhaps the strongest evidence we've ever acquired in support of the Big Bang has been the discovery of the leftover radiation from its early, hot, dense state: today's cosmic microwave background, or CMB. While there were many competing ideas for our cosmic origins, only the Big Bang predicted a uniform, omnidirectional bath of blackbody radiation: exactly what the CMB is.

But it turns out the CMB encodes much more information than just our cosmic origins; it allows us to map the very early Universe from when it was just 380,000 years old, and gives us vital information about what has happened to light from that time over its 13.8 billion year journey to our eyes. It encodes information about our cosmic expansion history, about dark matter and dark energy, about intervening galaxy clusters, and about the material here in our own galaxy, along with much more. It is, arguably, the richest source of information from any one single observable in our entire Universe.

Here to guide us through what CMB scientists are working on here in 2025, including what we've learned and what we're still trying to find out, I'm so pleased to welcome Dr. Patricio Gallardo to the show. We've got more than an hour and a half of quality science to go through, and by the end, I bet you'll be more excited about the upcoming Simons Observatory, designed to measure the CMB to higher precision than ever before, than you knew you should be. Enjoy!

(This image shows the Large Aperture Telescope's colossal, 6-meter primary and secondary mirrors at the Simons Observatory in February of 2025. The telescope has already seen first light, and will soon begin delivering new CMB science as never before. Credit: M. Devlin/Simons Observatory)


Starts With A Bang #119 - The CMB

How PFAS From A Military Base Has Sickened Nearby Residents

Adam Aleksic Responds To Callers' Words

Out there in the Universe, somewhere, a second example of an inhabit world or planet likely awaits us. It could be some other planet or moon within our own Solar System; it could be a spacefaring, interstellar civilization, or it could be an exoplanet around a different parent star. Although the search for life beyond Earth generally focuses on worlds that have similar conditions to Earth, like rocky planets with thin atmospheres and liquid water on their surfaces, that's not necessarily the only possibility. The truth is that we don't know what else is going to be out there, not until we look for ourselves and determine the answers.

And yet, if you've been paying attention to the news, you might think that super-Earth or mini-Neptune type worlds, such as the now-famous exoplanet K2-18b, might be excellent candidate planets for life. Some have even gone as far as to claim that this planet has surefire biosignatures on it, and that the evidence overwhelmingly favors the presence of life within this planet's atmosphere. But the science backing up that claim has been challenged by many, including our two podcast guests for this episode: Dr. Luis Welbanks and Dr. Matthew Nixon.

Beyond the breathless and sensational claims, what does the actual science concerning K2-18b in particular, and of biosignatures on exoplanets in general, actually teach us? What does the evidence indicate, and if we are going to find inhabited exoplanets, what will it take for us to actually announce a positive detection with confidence and less ambiguity? That's what this episode of the Starts With A Bang podcast is all about; I hope you enjoy it!

(When an exoplanet passes in front of its parent star, a portion of that starlight will filter through the exoplanet’s atmosphere, allowing us to break up that light into its constituent wavelengths and to characterize the atomic and molecular composition of the atmosphere. If the planet is inhabited, we may reveal unique biosignatures, but if the planet has either a thick, gas-rich envelope of volatile material around it, or alternatively no atmosphere at all, the prospects for habitability will be very low. ⁠Credit⁠: NASA Ames/JPL-Caltech)


Starts With A Bang #101 - Quantum Computing

Ethan Siegel