Observing the great gas giant helps me to keep important things in perspective.
Like a lot of people, I'm worried. I'm worried about the politics of hatred and its seeming steady rise across the world. I'm worried about the way new digital technologies seem to be unweaving the fabric that allows democracies to function.
Most of all, I'm worried about the rapidly changing climate and the cascade of impacts it will force on our cherished project of civilization. Sometimes, this worry is enough to literally keep me up at night.
That's when I remember where the real power lies, and I look at videos of the sun.
Over the last few decades, astronomers have gotten really good at observing the closest star to us—our sun, which is pretty ordinary as stars go. It's not exactly average, since lower mass stars are the most common. But the sun is no prize winner, and it's not going to get itself placed in any record books. It's not really big. It's not really bright. It's doesn't have cosmic scale explosions that can be seen from across the galaxy. It's just a smallish G-type star living its life in a not particularly interesting corner of the Milky Way. It seems completely non-descript.
Until you really look at it.
Please take three minutes to watch this video, and you'll see what I mean:
You can see that our sun—that every-day, bright yellow disk in the sky—hosts the power of a god. Like every star, the sun is a ball of ionized gas that glows via energy released in fusion reactions at its core. The surface is where all that energy is released, and just a few minutes of watching the sun's surface activity is enough to change your opinion about the real nature of what's going on in our lives.
There are vast plumes of plasma—thousands of times larger than Earth—blown 100,000 miles into space that fall back to surface like rain from hell. There are giant arcs of magnetic field that form a fibrial network the extending across the entire disk of the sun. Watch long enough, and these ethereal webs of magnetic energy will shudder and short out, reconnecting their arcs from one location to the other and releasing hurricanes of light in the process. When the fields really “let go," they can create explosions that drive planet-sized cannonballs of plasma into space with an energy equivalent to a billion aircraft carriers moving at 1 million miles per hour.
A profound narrative
All this mayhem and power, revealed through the eyes of science, has a profound lesson to teach us.
Watching a few minutes of solar activity reminds me that whatever moment in history I am living through, its story is just one of many. Each tiny eruption on the sun is a narrative of titanic forces unbalancing and rebalancing. And each is powerful enough to put all the arsenals on Earth to shame. Simply put, what I see watching the sun is that whatever I'm worrying about doesn't matter much at any scale larger than the daily frame of my life.
Now please don't misunderstanding me. We should be deeply concerned about the suffering of others. We should be, and must be, committed to actions that alleviate that suffering. We can and should look for opportunities every day that contribute to supporting a future of freedom, equality, and thriving for all living things.
That is the good, necessary work of being human in whatever moment you were born into.
But it's also important to see how our lives are embedded in a bigger story that is equally true and equally real. The sun shows us one, very local aspect, of this “cosmic perspective." It tells us just how remarkable, extraordinary, and awe-inspiring our vast home of the universe really is.
What that means, for me at least, is that I should just get on with the helping day-to-day and let go of the worrying. That's what the stars—and the Sun most of all—have shown me.
Since the late 1800s, what we know has advanced light years ahead.
If you bring up climate science at Thanksgiving dinner this year, what do you think will happen? Well, if you are like a lot of people, you might find yourself in the middle of a fight about the end of civilization or vast global hoaxes.
The instant polarization concerning climate science is nothing short of bizarre when you take the second part of the term—science—seriously. That’s because the science of climate science has made such remarkable advances over the last half-century, it should rightly be considered one of the great triumphs of humanity.
To understand how far climate science has come, you really have to focus on how far climate science has gone. That’s because we have a lot more than one planet, and one climate, to study these days.
Climate science is often called the study of long-term weather patterns. It may or may not rain tomorrow—that’s “weather,” not climate, and it gets hard to predict beyond a few days. But global circulation patterns, which move water around over yearlong timescales, are quite predictable. That’s because rotating planets with atmospheres that are heated on one side by a star represent a physical system that obeys very well-understood laws. Those laws translate into a basic understanding of how climate works and how it can change. Of course add an ocean, glaciers, volcanoes, and perhaps even life into the mix, and the whole system gets very complicated. But it’s still just the laws of physics and chemistry at work, and that means with enough effort, climate systems can be understood.
Earth was, of course, the first climate system people studied. It began back in the late 1800s when it became clear that the planet had undergone prolonged periods of cold called ice ages. Having huge areas of the Northern Hemisphere under a mile or two of ice for 100,000 years is definitely a problem of climate and not merely weather. The pioneers of the field struggled to understand what forces could drop the planet into the freezer for so long and, just as important, what forces got it out.
Anthropogenic climate forcing
It’s worth noting that one consequence of these early climate study efforts was the first recognition of “anthropogenic climate forcing.” The Swedish chemist Svante August Arrhenius was trying to understand the role of CO2 in ice ages when his calculations revealed the human use of coal was already starting to warm the planet. (Tell that to your climate-denying uncle who claims “global warming” is a modern hoax.)
But as the 20th century progressed, scientists eventually found themselves with more than one climate to study. Telescopic investigations of Mars and Venus opened up questions of a distinctly climatic nature. Radio observations of Venus implied surface temperatures of 700 degrees Fahrenheit, hotter than anyone could understand initially. And Mars not only showed seasons in the form of polar ice caps that grew and retreated, it also appeared to change color for months at time.
Once the space program took off, robotic probes to the planets gave scientists such a rich treasure trove of data that “comparative climate studies” became an actual thing. The insanely high temperatures on Venus were found to come from a runaway greenhouse effect. The occasionally strange colors of Mars came from planet-enveloping dust storms where tiny wind-blown particles absorbed sunlight, darkening the world below. What was learned from both of these planets was soon incorporated into the study of Earth’s climate where, for example, the role of dust became essential to understanding the terrifying possibility of a “nuclear winter.”
Soon every planet in the solar system with an atmosphere joined the comparative climate studies list. Jupiter, Saturn, Uranus, Neptune—they have all been investigated and they have all yielded new insights and new mysteries. We even have Titan, the giant moon of Saturn with a dense hydrocarbon atmosphere. Titan is the only other world with liquid on its surface—but you wouldn’t want to swim in it; it’s liquid methane.
These days, the frontiers of comparative climate studies lie light years out in space. We have discovered so many planets orbiting so many stars that the study of their possible climates now occupies a lot of astronomers. For a few worlds, we already have observations that translate into day and nighttime temperatures, the most basic of climate data. More important, over the next few decades telescopes will come on line that will let us study these climates in remarkable detail. The most exciting possibility is that we’ll find biospheres existing as part of the climate systems on some of these other worlds.
So don’t let anyone fool you. The “science” in “climate science” is not just healthy and robust; it’s some of the most exciting work out there.
The process of digging into hard questions makes the moment of discovery all the more satisfying.
What’s the hardest thing about being a scientist? Is it the years and years of training with no certainty that it will ever lead to a steady job? Is it the endless hours of writing grant proposals, most of which will never be funded?
While those are certainly difficulties, I believe that the hardest thing about being a scientist is not be able to tell other people the immense and profound joy that comes through finding something out.
One of the weirdest things about research is the month-long rabbit holes you can find yourself scurrying down in search some elusive, arcane, but oh-so-important fact. When, after all those weeks in the darkness, you finally find your answer, it’s nothing less than soul-satisfying. The pleasure that comes in these moments is deep and rich—and really, really hard to explain to your loved ones, who are apt to look at you sideways when you try.
Let me give you an example.
For the last month I’ve been on the hunt for the answer to a simple question about asteroids—which is not a subject I’ve spent any time researching before. Asteroids are basically chunks of rock and metal orbiting the sun—basically “construction debris” left over from the era of planet building when our solar system was very young (about 4 billion years ago). Since then, asteroids have been moved around via gravitational nudges from the planets—including the many in the Asteroid Belt between Mars and Jupiter.
Occasionally, asteroids slam into each other, creating smaller bodies—which is why there is a wide range of asteroid sizes, running from a few hundred meters all the way up dwarf planets with diameters of 1000 km like Ceres (shown at the top of this page). Smaller bits of rock—meteoroids—are as small as sand grains floating in space, and the line between them and an asteroid is a matter of definition.
So why was I thinking about asteroids and what was my question?
Don’t laugh, but I wanted to know which asteroids would make good space stations. Seriously, the idea of hollowing out asteroids and using their interiors for human habitation has gotten a lot of ink over the last decade. I first read about it in science fiction books, and then it popped up in a few scientific studies.
My question was simple: How many asteroids could serve as space habitats?
Running into rubble
I soon learned from Alice Quillen, my fellow prof at the University of Rochester, that most asteroids are not made of solid rock but of rubble piles. A rubble pile is basically a bunch of debris held loosely together by its own collective, weak gravity. They’re not solid, and wouldn’t offer any structural stability, so you wouldn’t want to use them as the basis for space-station construction.
But digging deeper, I learned that only smaller asteroids are expected to be rubble piles. The larger ones are believed to be solid rock. So now I needed to know how many “large” asteroids are in the solar system—that is, once I understood what “large” meant, in terms of diameter. Given that asteroids are a pretty well-studied subject—via years of telescope and space probes—it was a question that had to have an answer.
The rabbit hole was now open.
I needed to know the cut-off (in size) between “small” (rubble-pile asteroids) and “large” (solid ones). Once I knew that answer, I could feed it into mathematical models and projections to learn the total number of large, solid asteroids out there.
Nope. I could lay out the exact path I took through the scientific literature on my way to the answer, but I’ll tell you this much—it wasn’t a straight line. There were lots of problems. Different scientists had different opinions about where the rubble pile limit was in terms of asteroid diameter. Then came finding the right mathematical form, which was already spelled out in lots of papers. The only problem was getting the “constants,” the numbers that don’t change, in the equation. That took some hunting too.
The thrill of the hunt
But here is the thing: All that hunting, all those hours reading papers, review articles, and websites—it was all soooo much fun. I was always learning even when I was going down a dead end. And when I found some number or mathematical expression that got me a little closer to where I needed to be, it felt like finding a nugget of buried treasure.
And then, finally, I stumbled on a NASA JPL website that gave me everything I needed. (If I’d been an expert in the field, I would have known it existed from the get-go. Sigh).
So, I’d found it. I found my answer.
If we say the cutoff diameter between rubble pile and solid asteroids is 50 kilometers (31 miles), then there are about 800 asteroids out there waiting to for us to build cozy habitats. Now, the big asteroids might be problematic for setting up shop for their own reasons.
But the point here is not the number, but the exquisite joy I experienced for just a few moments when I found the number. It was truly a beautiful thing that has to be experienced to be appreciated. I felt like I’d learned something valuable, like I had gained some key insight into the nature of the world even though I knew 99 percent of the world likely didn’t care.
So, it’s that feeling, that sense of joy that you can’t explain to anyone but another scientist. That is hardest thing about the job.
I hope you can find your own form of this feeling in your own life, because there are many versions that come from making art or music or cooking or gardening, or whatever is your thing.
The process of learning—particularly that eureka the moment of discovery—is about the best thing imaginable.
Superposition, entanglement, qubits, and Google's big announcement.
According to last week’s news, the world took a giant step into the brave new world of quantum computing.
Researchers at Google announced that a machine at their labs had crossed the much-heralded milestone known as quantum supremacy. The announcement made headlines in pretty much every news outlet I came across.
Given that much coverage, I thought now would be a good time to think about which parts of quantum mechanics are involved with quantum computing.
“Quantum supremacy” is a term invented by the famous quantum physicist John Preskill in a 2012 paper. The idea he was trying to express was the moment when a quantum computer could do a calculation which a normal (or “classical”) computer could not. In practice, this means building a quantum computer that can compute something (like a random number) in a time much shorter than a classical computer could achieve. The idea is that there will be tasks which even a solar system–sized classical computer would take a billion years to finish—but a quantum machine could finish in a millisecond. That, in principle, is the kind of transition which happened last week at Google labs.
So, what’s going on that lets quantum computers do things that the kind of machine you’re reading this on now can’t? The answer turns on two particular aspects of quantum mechanics that pretty much stomp our commonsense ideas about the world into the ground.
The first aspect is what’s called superposition. In classical physics (and common-sense experience), things have definite properties. Take location, for example. I am either in the bedroom or I am not. How about speed? I am either traveling at 60 miles an hour or I’m not. Now perhaps there might be some slop associated with your measurements, so that you might not be able to tell if I’m traveling 60 miles an hour or 58 miles an hour. That’s just a detail, however. Whatever its actual value might be, most of us are sure that there is a real and definite speed that I’m traveling. But in quantum physics, this is not the case.
Before a measurement of some property—of, say, an electron—is made, quantum physics tells us it will be in a superposition of “states” for that property. Using the example of location again, before a measurement is made, the electron will be in the bedroom and in the kitchen and upstairs and in the family room of the house down the street—in all of these places at the same time. Physicists say the locations are “superposed”—that the electron doesn’t have just one value of a property, but has many at once.
Wait, It gets even weirder
The second kind of weirdness at the heart of quantum computing is what’s called entanglement. Normally we imagine that two objects that are widely separated can’t instantaneously affect each other. A ringing alarm clock in Singapore shouldn’t wake a sleeping dog in Denver. If the objects are so far apart that a light signal (the fastest signal possible) can’t make it between them in the time they are affecting each other, then such an effect is physically impossible.
But in quantum mechanics, particles can be “entangled.” If you entangle two electrons and move them to opposite sides of the solar system, an operation (i.e., a measurement) made on one of the pair will instantly change the state of the other. Entanglement means that, in a very real sense, the two electrons represent a kind of whole that a separation does not disturb. It’s like those stories of identical twins who can magically feel each other’s pain even if they are continents apart. In this case, however, it’s not magic, it’s quantum mechanics. (And no, you can’t use entanglement to send signals faster than light speed. Sorry.)
So, if superposition and entanglement seem really weird to you, that’s good. They are weird to us physicists. And if you want to know what’s really going in terms of how the world is built such that superposition and entanglement are possible, well then that’s good too, because most of us physicists want to know that as well. Mostly we’re clueless, though, which would lead to a whole discussion about quantum interpretations . . . which we’ll forgo for now.
The final question, of course, is how does any of this lead to quantum computers being supreme in terms of, you know, computing? The answer is actually simple. A classical computer is built on manipulating information in the form of bits, each of which can be 1 or 0. But a quantum computer uses qubits, which are superpositions of bits. That means a qubit is both 1 and 0 at the same time (until a measurement is made on it). That’s twice as much information in a single “unit” of computation. But that doubling is just the beginning. I can entangle qubits. That means if I have 2 qubits, I get 2×2 more information. If I have 5 qubits that increase goes up to 2x2x2x2x2 or 2 = 32. With just 50 entangled qubits, the information I’m working with goes up about a thousand billion times above what’s available with 50 classical bits. See? That’s pretty supreme supremacy.
The trick is getting anything done with those qbits since they are notoriously sensitive and tend to kind of fall apart at the slightest nudge. But that’s is another story which will have to wait for another day.