This false-color look inside the star-forming region G333.23–0.06 shows ALMA data of multiple systems of high-mass protostars. Within these clumps of matter, ALMA has found multi-star systems, with singlet stars being a relative rarity. (Credit: S. Li, MPIA / J. Neidel, MPIA Graphics Department; Data: ALMA Observatory)
Here in our Solar System, we only have one star: a singlet. For many systems, including the highest-mass ones, that’s anything but the norm.
Humanity once thought our Solar System was typical.
Here in our own Solar System, a single star anchors the system, where inner, rocky planets, an intermediate-distance asteroid belt, and then more distant gas giant planets eventually give way to the Kuiper belt and Oort cloud. For a long time, we assumed this configuration was typical and common. Today, we know better. (Credit: NASA/Dana Berry)
The other stars, presumably, were Sun-like objects, but very far away.
The brightness distance relationship, and how the flux from a light source falls off as one over the distance squared. The earliest estimates for the distances to the stars assumed they were intrinsically as bright as the Sun, and that their faint appearance was solely caused by their great distance from us. (Credit: E. Siegel/Beyond the Galaxy)
We soon learned that stars and stellar systems varied tremendously.
The (modern) Morgan–Keenan spectral classification system, with the temperature range of each star class shown above it, in kelvin. In terms of size, the smallest M-class stars are still about 12% the diameter of the Sun, but the largest main sequence stars can be dozens of times the Sun’s size, with evolved red supergiants (not shown) reaching hundreds or even 1000+ times the size of the Sun. A star’s (main sequence) lifetime, color, temperature, and luminosity are all primarily determined by a single property: mass. (Credit: LucasVB/Wikimedia Commons; Annotations: E. Siegel)
Individual stars come in many different masses, temperatures, and colors.
Binary systems typically have unequal masses, unequal brightnesses, and orbit a barycenter that lies outside of both stars. Only if the alignment with respect to us is sufficiently edge-on, at right, will it appear as an eclipsing binary. Wide binaries, with separations of thousands of astronomical units (AUs), are exceptionally difficult to characterize. Approximately 35% of all stars are found in binary systems, with half in singlet systems and the remainder in trinary or even richer multi-star systems. (Credit: Zhatt and Stanlekub/Wikimedia Commons)
While our Solar System has just one star, half of all stellar systems have multiples.
The richest star system among the more familiar stars is Castor: the 24th brightest star in the sky and an intrinsically sextuple system. Unlike our Sun, which is the only star in our system, practically half of all stars have one or more companions in their stellar systems. (Credit: NASA)
The central concentration of this young star cluster found in the heart of the Tarantula Nebula is known as R136, and contains many of the most massive stars known. Among them is R136a1, which comes in at about ~260 solar masses and shines brighter than more than 8 million suns, making it the heaviest known star. Although great numbers of cooler, redder stars are also present, the brightest, bluest ones dominate this image, although they have the shortest lifetime, living for between 1–10 million years only. Finding populations of nearby, dust-free massive stars is an exceedingly challenging task; R136 is over 165,000 light-years away. (Credit: NASA, ESA, CSA, STScI, Webb ERO Production Team)
But what about the heaviest, most massive stars of all?
This fragment of the young star-forming region NGC 2014 showcases many stars that are bluer, more massive, and much shorter lived than our Sun. However, the fainter, redder, less luminous stars are far more numerous, making us wonder just what “typical” truly is for a star. NGC 2014 is also found in the Large Magellanic Cloud: over 160,000 light-years away. (Credit: NASA, ESA and STScI)
They’re too short-lived to perform an accurate census of them.
The normal, multi-armed spiral galaxy IC 342, as imaged by ESA’s Euclid, with a Fibonacci spiral overlaid atop it. As you can clearly see, the shape of the spiral arms and the shape of the Fibonacci spiral do not match. (Credit: ESA/Euclid/Euclid Consortium/NASA and Ag2gaeh/Wikimedia Commons, stitched together by E. Siegel.)
The pattern 1, 1, 2, 3, 5, 8, 13, etc., is the Fibonacci sequence. It shows up all over nature. But what’s the full explanation behind it?
One of the most fascinating facts about the natural world is that so many entities within it — both biologically and purely physically — obey a specific set of patterns and ratios. Many galaxies exhibit spiral shapes and structures, as do a wide variety of plant structures: pinecones, pineapples, and sunflower heads among them. Ammonites, shelled animals that went extinct more than 60 million years ago, also show that spiral pattern, where one of the key features of spirals is that the next “wind” around outside the prior one displays a specific length ratio to the size of the prior, interior winding.
That ratio, in any such structure, is often extremely close to the ratio of two adjacent numbers found in the Fibonacci sequence. This mathematical sequence, often taught to children, simply starts with the numbers “0” and “1” and then gets the next term in the sequence by adding the two prior terms together. It’s arguably the most famous mathematical sequence of all, but what explains the sequence’s pattern, and is it truly, inextricably linked to nature? That’s what Ragtag Media wrote in to ask, inquiring:
“Is there a Fibonacci sequence with regards to the way galaxies develop?”
Indeed, simply looking at the “spiral” structures in galaxies might appear to be Fibonacci-like, but is that real, or just our minds making superfluous connections where only an apparent link exists?
This MIRI view, from JWST and the PHANGS collaboration, of spiral galaxy NGC 1566 shows heated, dusty and nuclear features that are entirely invisible to other observatories observing in optical/UV and even radio wavelengths. This dust filament network is ubiquitous in spirals, but the spirals themselves do not follow the pattern one might expect from the golden ratio or the Fibonacci sequence. (Credit: NASA/ESA/CSA/Judy Schmidt)
Galactic and other physical spirals
When it comes to spirals that naturally occur in the purely physical sciences, “spiral galaxies” are undoubtedly the most famous among them. Somewhere just over half of all known large, nearby, massive galaxies have spiral shapes and structures within them, but when we examine them mathematically, it turns out that there are very few of them that exhibit a Fibonacci-like pattern.
Einstein, shown here at a Princeton luncheon in 1953, was not only a physics genius and global celebrity, but a kind and just man who was generous with his advice, time, and lessons for those who were willing to listen. (Credit: Ruth Orkin)
The most celebrated genius in human history didn’t just revolutionize physics, but taught many valuable lessons about living a better life.
When it comes to living your best life, Albert Einstein — notorious as the greatest physicist and genius of his time, and possibly of all-time — probably isn’t the first name you think of in terms of life advice. You most likely know of Einstein as a pioneer in revolutionizing how we perceive the Universe, having given us advances such as:
the constancy of the speed of light,
the fact that distances and times are not absolute, but relative for each and every observer,
his most famous equation, ,
the photoelectric effect,
the theory of gravity, General Relativity, that overthrew Newtonian gravity,
and Einstein-Rosen bridges, or as they’re better known, wormholes.
But Einstein was more than just a famous physicist: he was a pacifist, a political activist, an active anti-racist, and one of the most iconic and celebrated figures in all of history.
He was also known for his unconventional behavior in a variety of ways that flouted social norms, including his unkempt hair, his witty humor, and his unrelenting hatred of socks. But less well-known is Einstein’s freely-given life advice to many of his friends, acquaintances, and contemporaries, which are perhaps even more relevant today, in the 21st century, than when he initially doled out his words of wisdom and compassion. Taken from the book The Einstein Effect, written by the official social media manager of the Einstein estate, Benyamin Cohen, these rules for a better life go far beyond physics and are relevant to us all. Here are, perhaps, the best and most universally applicable lessons from Einstein himself.
Einstein, shown here in 1940 receiving American Citizenship, was known around the world for his disheveled appearance and always wearing the same few sets of clothes, perhaps even better than he was known for his scientific theories. (Credit: New York World-Telegram/Al Aumuller)
Rule #1: Expend your efforts on the things that matter.
When you think of Einstein’s appearance, the word “disheveled” may come to mind. His overgrown…
At the start of the hot Big Bang, the Universe was rapidly expanding and filled with high-energy, very densely packed, ultra-relativistic quanta. An early stage of radiation domination gave way to several later stages where radiation was sub-dominant, but never went away completely. (Credit: CfA/M. Weiss)
For every proton, there were over a billion others that annihilated away with an antimatter counterpart. So where did all that energy go?
Today, our Universe is filled with stars and galaxies, and is not only expanding, but the Universe’s expansion is accelerating. If we were to break up the Universe into the different types of energy that compose it, we’d find that it was dominated by dark energy, which makes up 68% of the Universe’s energy density. Next would be dark matter, as it composes some 27% of the Universe’s energy density, followed by normal matter (protons, neutrons, and electrons), that makes up about 4.9% of all that’s out there. The other 0.1%? That’s made of things like neutrinos and photons, where all photons and the fastest-moving neutrinos both behave as forms of radiation.
But if you think about how all that radiation came to exist, an enormous amount of it is left over from the Big Bang, and was generated when massive particle-antiparticle pairs annihilated. So why, if there were so many more particle-antiparticle pairs that annihilated as compared with the matter particles that get “left over” as normal matter, doesn’t radiation play a bigger role in the Universe? That’s what Terry Bollinger wants to know, writing in to ask:
“Since the early hot universe was an almost equal mix of matter and antimatter, shouldn’t the total gravitational mass of the cosmic microwave and neutrino backgrounds be billions of times greater than that of fermionic matter?”
The quick answer — before we unpack the in-depth explanation behind it — is that it was greater, once. But no longer. Here’s the science behind why.
Just as raisins within a leavening ball of dough will appear to recede from one another as the dough expands, so too will galaxies within the Universe expand away from one another as the fabric of space itself expands. The fact that all methods of measuring the expanding Universe don’t give the same rate of expansion is troublesome, and may point to a problem with how we presently model the expansion of the Universe. (Credit: Ben Gibson/Big Think; Adobe Stock)
What you see, above, is an illustration of the expanding Universe. It’s also an illustration of an unleavened ball of dough with raisins randomly sprinkled throughout it. If you were to take this ball of unleavened dough up to the International Space Station — where it would experience effective weightlessness — and let it leaven with time, you’d…
Around the star WASP-69, a “hot Jupiter” exoplanet has its outer layers of atmosphere photoevaporated away, creating a comet-like tail whose extent and mass are being measured for the first time. (Credit: W. M. Keck Observatory/Adam Makarenko)
Planets can be Earth-like or Neptune-like, but only rarely are in between. This hot, Saturn-like planet hints at a solution to this puzzle.
It was only a little over 30 years ago, in the early 1990s, that humanity detected our first planets in orbit around stars other than the Sun: the exoplanets. The earliest ones discovered were a bit of a surprise: they were all massive, in tight orbits around their parent stars, and extremely hot: a class known as hot Jupiters. Since that time, we’ve discovered more than 5000 exoplanets, ranging from sub-Earth sized all the way up to super-Jupiters, with a huge variety found in between. However, two puzzles have arisen:
the fact that there are “hot Earths” and “hot Jupiters,” but no “hot Neptunes” in between them,
and the fact that there are plenty of Earth-like planets up to about 140% the radius of Earth, and plenty of Neptune-like planets down to about half the size of Neptune (about 200% the radius of Earth), but preciously few planets in that in-between range: a puzzle known as the radius gap.
The idea of the radial velocity method is that if a star has an unseen, massive companion, whether an exoplanet or a black hole, observing its motion and position over time, if possible, should reveal the companion and its properties. This remains true, even if there’s no detectable light emitted from the companion itself. (Credit: E. Pécontal)
The first successful methods for finding exoplanets involved measuring the light from a parent star very exquisitely. If there are planets orbiting the star in question, the star isn’t only going to gravitationally pull on that planet, but the planet will gravitationally pull on the star, causing the star to move in an elliptical pattern around the mutual center-of-mass of the star-planet system. That causes the star to appear to “wobble” with respect to us, as it will periodically move towards-and-away from us leading to its light redshifting and blueshifting in a periodic fashion. This detection method, known as either the radial…
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!
As sunlight strikes Earth from space, it doesn’t fall on the planet equally in all locations. The Earth has a three-dimensional, spheroidal shape, but sunlight simply spreads out in a sphere as it leaves the source. The locations on Earth that “see” the Sun as directly overhead experience the greatest amount of solar irradiance at their surface, while the locations closest to the horizon, as illuminated here, experience the least energy of all locations illuminated by the Sun. (Credit: Fyodor Yurchikhin/Russian Space Agency)
Figuring out the answer involved a prism, a pail of water, and a 50 year effort by the most famous father-son astronomer duo ever.
When it comes to planet Earth, the most important source of light, heat, and energy actually comes from beyond our world. It’s the Sun that is the driver of the Earth’s energy balance, rather than the internal heat given off by the planet itself from sources like gravitational contraction and radioactive decays. The energy from the Sun keeps temperatures from freezing all across the planet, providing us with temperatures that allow liquid water on Earth’s surface, and that are essential to the life processes of nearly every organism extant on our world today.
And yet, it’s only within the last 200 years that humanity has even understood how much energy, overall, the Sun actually produces. Considering all of the scientific advances that came afterwards, including the development of stellar, quantum, and nuclear physics, as well as the understanding of the subatomic fusion reactions that power the Sun, it might seem like a trivial matter to simply answer the question of “how much energy does the Sun produce?” But looks can be deceiving. If you didn’t already know (or hadn’t already googled) the answer to that question, how would you figure it out? Here’s how humanity did it.
When sunlight strikes the Earth’s surface, it has already been processed: by not only its journey from the Sun to the Earth, but by Earth’s atmosphere, clouds, and all objects that absorb or emit light along its journey to us. Here’s how we did our best to overcome those limitations and measure the Sun’s power output. (Credit:pixpoetry/Unsplash)
The Solar System is not enough
You might think to yourself that simply knowing a few physical properties about the Sun, such as:
how big it is,
how massive it is,
and how far away from Earth it is,
would go a long way towards delivering the answer to such a question. After all, you can see, with even extremely primitive tools (like your naked eye and a sextant), you can determine how large, in terms of angular size, the Sun is. Since ancient times, it’s been known that the Sun is approximately half-a-degree across from end-to-end, with more modern measurements confirming that its angular size varies from 31.46 to 32.53 arcminutes over the course of a year. (Where 60 arcminutes equates to one degree.)
This conceptual image shows meteoroids delivering all five of the nucleobases found in life processes to ancient Earth. All the nucleobases used in life processes, A, C, G, T, and U, have now been found in meteorites, along with more than 80 species of amino acids as well: far more than the 22 that are known to be used in life processes here on Earth. Similar processes no doubt happened in stellar systems all throughout most galaxies over the course of cosmic history. (Credit: NASA Goddard/CI Lab/Dan Gallagher)
Earth wasn’t created until more than 9 billion years after the Big Bang. In some lucky places, life could have arisen almost right away.
The cosmic story that unfolded following the Big Bang is ubiquitous no matter where you are. The formation of atomic nuclei, atoms, stars, galaxies, planets, complex molecules, and eventually life is a part of the shared history of everyone and everything in the Universe. Even though all of these things likely arise at somewhat different times at different locations in the Universe, largely dependent on the initial conditions such as temperature and density, once enough time goes by, they’re found literally everywhere. At least once, here on Earth, life began at some point in the Universe. At the absolute latest, it appeared only a few hundred million years after our planet was first formed.
That puts life as we know it arising, at the absolute latest, nearly 10 billion years after the Big Bang. When the Big Bang first occurred, life was impossible. In fact, the Universe couldn’t have formed life from the very first moments; both the conditions and the ingredients were all wrong. But that doesn’t mean it took all those billions and billions of years of cosmic evolution to make life possible. Based on when the raw ingredients that we believe are necessary for the most primitive forms of life to arise from non-life, it’s reasonable to think that “first life” might have come around back when the Universe was just a few percent of its current age. Here’s the best scientifically-motivated story for how life might have first arisen in our Universe.
The existence of complex, carbon-based molecules in star forming regions is interesting, but isn’t anthropically demanded. Here, glycolaldehydes, an example of simple sugars, are illustrated in a location corresponding to where they were detected in an interstellar gas cloud: offset from the region presently forming new stars the fastest. Interstellar molecules are common, with many of them being complex and long-chained. (Credit: ALMA (ESO/NAOJ/NRAO)/L. Calçada (ESO) & NASA/JPL-Caltech/WISE Team)
At the earliest moments of the hot Big Bang, the raw ingredients for life could in no way stably exist. Particles, antiparticles, and radiation all zipped around at relativistic speeds, blasting apart any bound structures that might have formed by chance. As the Universe aged, though, it also expanded and cooled, reducing the kinetic energy of everything in it. Over time, antimatter annihilated away, stable atomic nuclei formed, and electrons finally bound to…
The farther away we observe, the closer in time we find ourselves looking near the start of the hot Big Bang. Many of the earliest galaxies we’ve ever seen contain evidence for quite large supermassive black holes at their centers. Somehow, in rapid fashion, the Universe must have made them. (Credit: Robin Dienel/Carnegie Institution for Science)
As early as we’ve been able to identify them, the youngest galaxies seem to have large supermassive black holes. Here’s how they were made.
One of the biggest challenges for modern astrophysics is to describe how the Universe went from a uniform place without planets, stars, or galaxies to the rich, structured, diverse cosmos we see today. Not just with a general story, mind you, but in gory detail, going not only as far back as we can see, but even farther: to what must have existed at an epoch where even our most distant observations are insufficient to take us there. Going back to the limits of what’s observable, to when the Universe was just a few hundred million years old, we find a slew of fascinating objects.
Stars and star clusters exist in abundance.
Galaxies with perhaps up to a billion stars light up the Universe.
Even quasars with very large black holes formed early on: well before the Universe was even one billion years old.
It’s the old chicken-and-egg problem made new: if there’s a maximum rate at which black holes can grow, and the Universe wasn’t born with them, how did we make the ones that we see? In other words, how did the Universe make such ultra-massive black holes in such short periods of time? After decades of conflicting stories, scientists finally think we know what happened.
With millions of seconds (corresponding to hundreds of hours) of observations on this one region of the sky, just 0.11 square degrees in area, Chandra revealed hundreds of active supermassive black holes, as well as many other cosmic objects. X-ray observatories are very sensitive to the presence of active black holes. (Credit: ESO/Mario Nonino, Piero Rosati and the ESO GOODS Team)
Just 50-to-100 million years after the Big Bang, the very first stars of all began to form. Massive gas clouds started to collapse, but because they were made up of hydrogen and helium alone, they struggle to radiate heat away and dissipate their energy. As a result, these clumps that gravitationally form and grow need to get much more massive than clumps that form stars today, and that has repercussions for what kinds of stars form, as well as what kinds of astrophysical processes occur alongside their formation.
While today, typically, we form stars that are about 40% the mass of the Sun, the very first stars were about 25…
When the very first stars form in the Universe, they form out of hydrogen and helium alone. But when that first generation dies, it can give rise to a second generation that’s far more complex, intricate, and diverse. The resulting starburst from the forming of the second generation of stars may resemble Henize 2–10, a nearby star-forming galaxy located 30 million light years away. (Credit: NASA, ESA, Zachary Schutte (XGI), Amy Reines (XGI); Processing: Alyssa Pagan (STScI))
The first stars in the Universe were made of pristine material: hydrogen and helium alone. Once they die, nothing escapes their pollution.
When you look out at the Universe today, and see the vast, dark, backdrop littered with points of light that correspond to stars and galaxies, it’s difficult to imagine that it used to be almost identical everywhere. The Universe, back at its inception, was almost perfectly uniform on all cosmic scales. It was the same high temperature everywhere, the same large density everywhere, and was made up of the same quanta of matter, antimatter, dark matter, and radiation in all locations. At the earliest times, the only differences that existed were minuscule, at the 0.003% level, seeded by the quantum fluctuations imprinted during inflation.
But gravity and time have a way of changing everything. Over time, the excess antimatter annihilates away; first atomic nuclei and then neutral atoms form; over millions of years, gravity pulls matter into overdense regions, causing them to grow. Because overdensities differ by such great amounts on all scales, there are regions where stars form rapidly, within 100 million years or fewer, while other regions won’t begin forming stars for billions of years. But wherever the earliest stars form, that’s where the most interesting things happen first, including the existence of the second generation of stars: the first polluted stars in all of cosmic history.
An illustration of the first stars turning on in the Universe. Without metals to cool down the clumps of gas that lead to the formation of the first stars, only the largest clumps within a large-mass cloud will wind up becoming stars: fewer in number but greater in mass than today’s stars. (Credit: NASA / WMAP Science Team)
The very, very first stars are born in the most initially overdense regions of all, which grow by attracting surrounding matter the fastest. The gravitational growth of matter leads to the first stars forming somewhere between 50 and 100 million years after the Big Bang, with those stars being much more massive than the stars we see today. Because there’s so much mass inside them, undergoing the rapid, high-temperature reactions of nuclear fusion, they live fast. Within just a few million years, they’ve burned through all of their core’s fuel, leading to their dying in either a supernova or by…
