Physics and Jazz
Stephon Alexander is an Associate Professor of Physics at Haverford College, focusing on theoretical cosmology, quantum gravity and particle physics. He is also an Assistant Professor (Adjunct) of Physics at Penn State University. Stephon has studied at Brown University and done postodoctoral research at Imperial College, London and at the Stanford Linear Accelerator Laboratory. He is on the Board of Directors for the Network for the Improvement of World Healthare, an action-driven organization that forges global partnerships to address local health challenges. He also plays jazz saxophone and sees improvisation as an extension of his scholarship.
Stephon Alexander: So, it’s interesting that a lot of modern jazz composers; some names that immediately come to mind; people like John Coltrane, Wayne Shorter; there was always directly; Sun Ra; and a deep appreciation, and even a very deep, intuitive understanding, of modern physics into their music.
And one of the things I like to do for fun is actually look for those connections, like literally- I talk to music composers and it’s like this hobby of mine, where I will take a Coltrane song, or the chord changes, and try to relate it to music theory and physics.
One thing I found interesting is the notion that Coltrane came up with, was something called; it was a sort of a musical illusion device in saxophone playing. See, a saxophone can’t play more than one note at a time. It’s a monophonic instrument. But what Coltrane was able to do was to come up with illusory effects on the saxophone--I call it that--and it was called sheets of sound. Or another thing that he did was figure out ways in which you can go to higher notes that a sax was wasn’t built to make.
And this uses ideas in physics, like non-linearity, for example, that there isn’t always a one-to-one correspondence between a wave and a note, and I mean, one wave- if I add two waves together, I get a third wave. There’s not always a one-to-one correspondence; that’s the difference between linear and non-linear.
And since music is a way a culture is able to figure out techniques to do that, ways in which, you know, you can hear more than one note at a time--and how is that related to physics? Well, quantum mechanics is exactly an example of that. A particle really can be; there’s a probability, in a sense, of a particle being here or here, then in a sense, you can think of it as occupying two places at the same time; until you go and measure it.
And the question is, well, that’s not hard to get your mind around, but in a sense that’s what the sheets of sound Coltrane was doing was like; because you are playing many ways, many different notes, on an instrument that can only play one note at a time. But there’s this overall effect in which all those notes are co-existing.
What the sheets of sound is; I’m going to be switching between different individual notes. So, for example, I’m going to play a “D”.
And I’ll play a “G”- I’m sorry, a “G.”
All right, and that’s a “C”- and if I play them very quickly.
But if Coltrane figured out alternative fingerings while playing those notes in a rapid succession that you get an effect that it sounds like this. So that’s an example of sheets of sound. Altissimo was basically that the sax normally can just go up to, say, this high F sharp. That’s a high F sharp for me.
But then you can go further by using a non-linear effect by, you know, using your diaphragm, down here, by forcing the resonance from down here. So I can go up to my high F sharp.
Stephon Alexander: Actually, I’m working on a little album project--it’s almost done, and the title of the album is called-- and a lot of the songs are inspired by my love for great cool ideas in physics and how it’s connected to jazz music, in particular--but actually it has a lot of. It also explores the idea of diversity and creativity, so it uses modern rhythms, like a Brazilian beat versus a Reggaeton beat versus a hip-hop beat. So it uses modern rhythms with jazz improvisations, combining it with themes and impressions--having to do with cosmology and particle physics and string theory. And the title of the album will be called Mathematics!
Because when I grew up in the Bronx in the Eighties, hip-hop music; there was a part of rap music where guys would battle each other on the streets, and sometimes the battling would go into the subject matter would be talking about science, for example, and they even called it droppin’ science, like Eric B and Rakim.
I used to take the bus home from school and these guys would be on the back of the bus around, rappin’ and battling each other- droppin’ science, so to speak, and one day, you know, I heard someone say, “Yeah, man, ‘cause I got enough mathematics.”
So it also captures a big part of my, you know, what inspired me, was that I was already living in sort of a- this rappin’ and improvisational rappin’- and talking about things around you in the universe, and stars exploding. But I’m like the star exploding. Planet Rock Afrika Bambaataa- one of the first rap songs out there.
So, that title of Mathematics sort of brings it all together.
Recorded June 2, 2008.
Alexander shares the music that most reminds him of physics. He even plays a few notes.
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The great theoretical physicist Steven Weinberg passed away on July 23. This is our tribute.
- The recent passing of the great theoretical physicist Steven Weinberg brought back memories of how his book got me into the study of cosmology.
- Going back in time, toward the cosmic infancy, is a spectacular effort that combines experimental and theoretical ingenuity. Modern cosmology is an experimental science.
- The cosmic story is, ultimately, our own. Our roots reach down to the earliest moments after creation.
When I was a junior in college, my electromagnetism professor had an awesome idea. Apart from the usual homework and exams, we were to give a seminar to the class on a topic of our choosing. The idea was to gauge which area of physics we would be interested in following professionally.
Professor Gilson Carneiro knew I was interested in cosmology and suggested a book by Nobel Prize Laureate Steven Weinberg: The First Three Minutes: A Modern View of the Origin of the Universe. I still have my original copy in Portuguese, from 1979, that emanates a musty tropical smell, sitting on my bookshelf side-by-side with the American version, a Bantam edition from 1979.
Inspired by Steven Weinberg
Books can change lives. They can illuminate the path ahead. In my case, there is no question that Weinberg's book blew my teenage mind. I decided, then and there, that I would become a cosmologist working on the physics of the early universe. The first three minutes of cosmic existence — what could be more exciting for a young physicist than trying to uncover the mystery of creation itself and the origin of the universe, matter, and stars? Weinberg quickly became my modern physics hero, the one I wanted to emulate professionally. Sadly, he passed away July 23rd, leaving a huge void for a generation of physicists.
What excited my young imagination was that science could actually make sense of the very early universe, meaning that theories could be validated and ideas could be tested against real data. Cosmology, as a science, only really took off after Einstein published his paper on the shape of the universe in 1917, two years after his groundbreaking paper on the theory of general relativity, the one explaining how we can interpret gravity as the curvature of spacetime. Matter doesn't "bend" time, but it affects how quickly it flows. (See last week's essay on what happens when you fall into a black hole).
The Big Bang Theory
For most of the 20th century, cosmology lived in the realm of theoretical speculation. One model proposed that the universe started from a small, hot, dense plasma billions of years ago and has been expanding ever since — the Big Bang model; another suggested that the cosmos stands still and that the changes astronomers see are mostly local — the steady state model.
Competing models are essential to science but so is data to help us discriminate among them. In the mid 1960s, a decisive discovery changed the game forever. Arno Penzias and Robert Wilson accidentally discovered the cosmic microwave background radiation (CMB), a fossil from the early universe predicted to exist by George Gamow, Ralph Alpher, and Robert Herman in their Big Bang model. (Alpher and Herman published a lovely account of the history here.) The CMB is a bath of microwave photons that permeates the whole of space, a remnant from the epoch when the first hydrogen atoms were forged, some 400,000 years after the bang.
The existence of the CMB was the smoking gun confirming the Big Bang model. From that moment on, a series of spectacular observatories and detectors, both on land and in space, have extracted huge amounts of information from the properties of the CMB, a bit like paleontologists that excavate the remains of dinosaurs and dig for more bones to get details of a past long gone.
How far back can we go?
Confirming the general outline of the Big Bang model changed our cosmic view. The universe, like you and me, has a history, a past waiting to be explored. How far back in time could we dig? Was there some ultimate wall we cannot pass?
Because matter gets hot as it gets squeezed, going back in time meant looking at matter and radiation at higher and higher temperatures. There is a simple relation that connects the age of the universe and its temperature, measured in terms of the temperature of photons (the particles of visible light and other forms of invisible radiation). The fun thing is that matter breaks down as the temperature increases. So, going back in time means looking at matter at more and more primitive states of organization. After the CMB formed 400,000 years after the bang, there were hydrogen atoms. Before, there weren't. The universe was filled with a primordial soup of particles: protons, neutrons, electrons, photons, and neutrinos, the ghostly particles that cross planets and people unscathed. Also, there were very light atomic nuclei, such as deuterium and tritium (both heavier cousins of hydrogen), helium, and lithium.
So, to study the universe after 400,000 years, we need to use atomic physics, at least until large clumps of matter aggregate due to gravity and start to collapse to form the first stars, a few millions of years after. What about earlier on? The cosmic history is broken down into chunks of time, each the realm of different kinds of physics. Before atoms form, all the way to about a second after the Big Bang, it's nuclear physics time. That's why Weinberg brilliantly titled his book The First Three Minutes. It is during the interval between one-hundredth of a second and three minutes that the light atomic nuclei (made of protons and neutrons) formed, a process called, with poetic flair, primordial nucleosynthesis. Protons collided with neutrons and, sometimes, stuck together due to the attractive strong nuclear force. Why did only a few light nuclei form then? Because the expansion of the universe made it hard for the particles to find each other.
What about the nuclei of heavier elements, like carbon, oxygen, calcium, gold? The answer is beautiful: all the elements of the periodic table after lithium were made and continue to be made in stars, the true cosmic alchemists. Hydrogen eventually becomes people if you wait long enough. At least in this universe.
In this article, we got all the way up to nucleosynthesis, the forging of the first atomic nuclei when the universe was a minute old. What about earlier on? How close to the beginning, to t = 0, can science get? Stay tuned, and we will continue next week.
To Steven Weinberg, with gratitude, for all that you taught us about the universe.
Long before Alexandria became the center of Egyptian trade, there was Thônis-Heracleion. But then it sank.
Before Alexander the Great established Alexandria around 331 BCE, one of Egypt's primary ports on the Mediterranean Sea between the sixth and fourth centuries BCE was a place called Thônis-Heracleion.
Now researchers from the European Institute for Underwater Archaeology (IEASM), the same organization that first found the city in 2001, have announced the discovery of a couple of fascinating items from the city's heyday. Pinned beneath fallen temple stones is a surprisingly intact Egyptian military vessel from the second century BCE, and researchers have excavated a large cemetery from the fourth century BCE.
Thônis-Heracleion was one of the two primary access points to ancient Egypt from the Mediterranean. (The other, Canopus, was discovered in 1999.) For millennia, experts assumed Thônis-Heracleion were two different lost cities, but it's now known that Thônis is simply the city's Egyptian name, while Heracleion is its Greek name.
Thônis-Heracleion had been the stuff of legend before it was located, mentioned only in rare ancient texts and stone inscriptions. Herodotus seems to have been referring to Thônis-Heracleion's temple of Amun as the place where Heracles first arrived in Egypt. He also described a visit there by Helen with her lover Paris just before the outbreak of the Trojan War. In addition, 400 years later, geographer Strabo wrote that Heraclion, containing the temple of Heracles, had been located opposite Canopus across a branch of the Nile. Today we know Thônis-Heracleion's location as Egypt's Abu Qir Bay. The sunken port is about 6.5 kilometers from the coast and lies beneath ten meters of water.
Both Thônis-Heracleion and Canopus were wealthy in their day, and the temple was an important religious center. This all ended when the Egyptian dynasty created by Ptolemy set out to establish Alexandria as Egypt's center. Thônis-Heracleion and Canopus' trade — and thus wealth — was diverted to the new capital.
It was perhaps just as well, given that natural forces eventually destroyed Thônis-Heracleion. Located on the Mediterranean, the ground upon which it was built became saturated and eventually began to destabilize and liquefy. The temple of Amun probably collapsed around 140 BCE. A series of earthquakes sealed the cty's' fate around 800 CE, sending a 100 square-kilometer chunk of the Nile delta on which it was constructed under the waves. The Mediterranean's rising sea level over the next couple thousand years completed the drowning of Thônis-Heracleion.
Researchers have recovered a large collection of Thônis-Heracleion's treasures revealing an economically rich culture. Coins, bronze statuettes, and over 700 ancient ship anchors have been pulled from the waters. Divers have also identified over 70 shipwrecks. A giant statue of the Nile god Hapi took two and a half years to bring up.
An ancient vessel and a cemetery
Gold mask found in a submerged Greek cemetery.Credit: Egyptian Ministry of Tourism and Antiques
The newly discovered ship was found beneath 16 feet of hard clay, "thanks to cutting-edge prototype sub-bottom profiler electronic equipment," says Ayman Ashmawy of the Egyptian Ministry of Tourism and Antiques.
The military vessel had been moored in Thônis-Heracleion when the temple of Amun collapsed. The temple's enormous blocks fell onto the ship, sinking it. The boat is a rare find — only one other ship of its period has been found. As underwater archaeologist Franck Goddio, one of the scientists who found the city, puts it, "Finds of fast ships from this age are extremely rare."
At 80 feet long, the boat is six times as long as it is wide. Like its dually-named city, it's an amalgam of Greek and Egyptian ship-building techniques. According to expert Ehab Fahmy, head of the Central Department of Underwater Antiquities at IEASM, the boat has some classical construction features such as mortar and tenon joints. On the other hand, it was built to be rowed, and some of its wood was reused lumber, signature traits of Egyptian boat design. Its flat bottom suggests it was built for navigating the shallows of the Nile delta where the river flows into the Mediterranean.
Also found alongside the city's submerged northeastern entrance canal was a large Greek cemetery. The funerary is adorned with opulent remembrances, including a mask made of gold, shown above. A statement by the Egyptian Ministry of Tourism and Antiques describes its significance, as reported by Reuters:
"This discovery beautifully illustrates the presence of the Greek merchants who lived in that city. They built their own sanctuaries close to the huge temple of Amun. Those were destroyed simultaneously and their remains are found mixed with those of the Egyptian temple."
Excavation is ongoing, with more of Egypt's ancient history no doubt waiting beneath the waves.
Geologists discover a rhythm to major geologic events.
- It appears that Earth has a geologic "pulse," with clusters of major events occurring every 27.5 million years.
- Working with the most accurate dating methods available, the authors of the study constructed a new history of the last 260 million years.
- Exactly why these cycles occur remains unknown, but there are some interesting theories.
Our hearts beat at a resting rate of 60 to 100 beats per minute. Lots of other things pulse, too. The colors we see and the pitches we hear, for example, are due to the different wave frequencies ("pulses") of light and sound waves.
Now, a study in the journal Geoscience Frontiers finds that Earth itself has a pulse, with one "beat" every 27.5 million years. That's the rate at which major geological events have been occurring as far back as geologists can tell.
A planetary calendar has 10 dates in red
Credit: Jagoush / Adobe Stock
According to lead author and geologist Michael Rampino of New York University's Department of Biology, "Many geologists believe that geological events are random over time. But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated and not random."
The new study is not the first time that there's been a suggestion of a planetary geologic cycle, but it's only with recent refinements in radioisotopic dating techniques that there's evidence supporting the theory. The authors of the study collected the latest, best dating for 89 known geologic events over the last 260 million years:
- 29 sea level fluctuations
- 12 marine extinctions
- 9 land-based extinctions
- 10 periods of low ocean oxygenation
- 13 gigantic flood basalt volcanic eruptions
- 8 changes in the rate of seafloor spread
- 8 times there were global pulsations in interplate magmatism
The dates provided the scientists a new timetable of Earth's geologic history.
Tick, tick, boom
Credit: New York University
Putting all the events together, the scientists performed a series of statistical analyses that revealed that events tend to cluster around 10 different dates, with peak activity occurring every 27.5 million years. Between the ten busy periods, the number of events dropped sharply, approaching zero.
Perhaps the most fascinating question that remains unanswered for now is exactly why this is happening. The authors of the study suggest two possibilities:
"The correlations and cyclicity seen in the geologic episodes may be entirely a function of global internal Earth dynamics affecting global tectonics and climate, but similar cycles in the Earth's orbit in the Solar System and in the Galaxy might be pacing these events. Whatever the origins of these cyclical episodes, their occurrences support the case for a largely periodic, coordinated, and intermittently catastrophic geologic record, which is quite different from the views held by most geologists."
Assuming the researchers' calculations are at least roughly correct — the authors note that different statistical formulas may result in further refinement of their conclusions — there's no need to worry that we're about to be thumped by another planetary heartbeat. The last occurred some seven million years ago, meaning the next won't happen for about another 20 million years.
We are likely to see the first humans walk on Mars this decade.
- Space agencies have successfully sent three spacecraft to Mars this year.
- The independent missions occurred at around the same time because Earth and Mars were particularly close to each other last summer, providing an opportune time to launch.
- SpaceX says it hopes to send a crewed mission to Mars by 2026, while the U.S. and China aim to land humans on the planet in the 2030s.
Spacecraft from three of the world's space agencies reached Mars this year.
In February, the United Arab Emirates' Hope space probe entered the Martian orbit, where it is studying the planet's weather cycles. That same month, NASA's Perseverance rover touched down on Mars, where it will soon begin collecting rock samples that could contain signs of ancient life. And in May, China successfully landed its Zhurong rover on the Martian surface, becoming the second nation to ever do so.
All three missions launched in the summer of 2020. The timing was no coincidence: once every two years, Earth and Mars come especially close together because their orbits are "at opposition," which is when the Earth-Mars distance is smallest during the 780-day synodic period. It is an opportune window to send spacecraft to Mars.
The handful of spacecraft currently exploring the Martian surface and atmosphere are scheduled to conduct their experiments for periods ranging from months to years. Some even plan to collect materials to return to Earth. For example, NASA's Perseverance will store its rock samples in protective tubes and leave them behind for a smaller "fetch rover" to pick up on a future mission.
Photo of Martian surface taken by the Perseverance roverNASA/JPL-Caltech
If all goes well, an Airbus spacecraft dubbed the Earth Return Orbiter (ERO) will carry the samples back to Earth in 2031. It would be the first time a space mission has returned Martian matter to Earth. But before the decade's end, space agencies have some other missions that aim to study the Red Planet.
Europe & Russia
NASA is not the only space agency aiming to find evidence of life on the Red Planet. In 2023, Roscosmos and the European Space Agency plan to land their Rosalind Franklin rover on the Martian surface, where it will drill into rock and analyze soil composition for signs of past — or possibly present — alien life.
The joint mission is part of a long-term Mars project that began in 2016. This second phase was initially planned for 2020, but due in part to the COVID-19 pandemic, the space agencies decided to postpone the launch to 2022.
"We want to make ourselves 100% sure of a successful mission. We cannot allow ourselves any margin of error. More verification activities will ensure a safe trip and the best scientific results on Mars," said ESA Director General Jan Wörner.
In 2022, the Japanese Aerospace Exploration Agency (JAXA) plans to send to Mars its TEREX lander, which will "precisely measure the amount of water molecules and oxygen molecules, and search for water resources and the possibility of life on Mars," JAXA wrote.
In 2024, JAXA also plans to launch a uniquely bold interplanetary mission that will involve sending a probe to orbit Mars, landing on the Martian moon Phobos, collecting surface samples, and then returning those samples to Earth in 2029. JAXA says the mission has two main objectives: (1) to investigate whether the Martian moons are captured asteroids or fragments that coalesced after a giant impact with Mars; and (2) to clarify the mechanisms controlling the surface evolution of the Martian moons and Mars.
Following the successful landing of its Zhurong rover this year, China released a roadmap of its plans for additional Mars voyages. The first is an uncrewed mission scheduled for 2030, with crewed missions planned for 2033, 2035, 2037, and 2041. As the International Space Station project is coming to a close, China is in the process of building its own space station; earlier this year it launched into orbit the first part of its station, which will take 10 more missions to assemble.
Elon Musk's California-based aerospace company has its sights on two Mars voyages: a cargo-only mission in 2022 and a human mission by 2026. The crewed mission would involve building a propellant depot and preparing a site for future crewed flights. Getting to Mars will first require an orbital test of SpaceX's Starship rocket, which the company hopes to conduct this year.
Regarding the long-term future of humans on the Red planet, Musk once told Ars Technica:
"I'll probably be long dead before Mars becomes self-sustaining. But I'd like to at least be around to see a bunch of ships land on Mars."
In 2014, the Indian Space Research Organization executed its first interplanetary trip with its Mars Orbiter Mission. It marked the first time an Asian nation reached Martian orbit and also the first time a nation successfully reached the Red planet on its maiden voyage. India has plans for a follow-up Mars Orbiter Mission 2, but it remains unclear when that will occur and what the mission will entail.
In February, the chief of the Indian Space Research Organisation said the nation would only launch a Mars mission after Chandrayaan-3, India's upcoming mission to the Moon, which is expected to launch in 2022.