Dust Covered the Origin of the Universe

Asked for the coolest measuring device humans have built, Keating sets aside his own cosmic-microwave-background polarimeters and names the telescope. Most people credit Galileo. The inventor, he says, was Hans Lippershey in the Netherlands. Galileo did something almost as radical as going from zero to one: he improved the instrument by a factor of ten.

The context is as interesting as the glass. Movable type gave Europe, for the first time, a fixed standard of eyesight — printed letters of known height. People who could not read the Gutenberg Bible suddenly knew their vision had failed, and craftsmen in Venice and the Netherlands stacked two pieces of glass to make the words sharp. Nobody thought to lift the same two lenses toward the bright thing in the sky until Galileo.

The telescope's twin is the microscope. The same trick looks out and looks in. Looking out has a hidden property: it is a time machine. Light travels about one foot per nanosecond, which you do not feel under a microscope. Point the same physics at Jupiter, the Moon, or the Andromeda galaxy, 2.5 million light-years away, and you are seeing the world as it was when Lucy walked the Serengeti. A radio telescope goes further. If a source fills the beam, a resistor at the focus comes to the same temperature as the object. You are taking Jupiter's temperature from hundreds of millions of kilometers away. Archaeology cannot do that.

Fridman asks what happened at the beginning. Keating says the honest way to answer is to walk backward from today. Go back 13.8 billion years and you land on a calendar day. On that day the universe became a fusion reactor, turning the lightest elements and isotopes into slightly heavier ones. The hydrogen in a bottle of water was, to a very good approximation, made in those first twenty minutes.

His joke is precise. The fusion and production of the lightest entries on the periodic table happened in a stretch shorter than an episode of *The Big Bang Theory*. Helium, lithium, and their kin are not the stuff of daily life unless you go to birthday parties or pilot a blimp. Heavier nuclei — iron, carbon, nickel — required a different reactor: a supernova. Walk back past those first three minutes, though, and physics has almost nothing to say. Steven Weinberg's book *The First Three Minutes* is a boundary line. Beyond it, ignorance takes over.

Most working cosmologists still believe the universe began in a singularity. Keating notes that the word appears in only two places, the Big Bang and the core of a black hole, and neither is observable. A singularity is not physics so much as the placeholder left when a mathematical extrapolation hits a wall. When he was in graduate school, alternatives were barely discussed. Now they are not fringe. The first cosmology in history, he jokes, was already cyclical: Akhenaten's Egypt, third millennium BCE, would have a high h-index by now.

Inflation is the spark that ignites the hot Big Bang Keating says we understand. It is an earlier condition, not an initial condition. His analogy is a grandfather clock. You walk into a room, see a pendulum swinging, and can measure its period and the damping from air resistance. You cannot say when it started. Solving a differential equation needs initial conditions and boundary conditions. Inflation supplies the latter and is silent on the former.

That gap is why alternatives have become serious again. Roger Penrose's conformal cyclic cosmology treats time as having no beginning. The quasi-steady-state universe, popular in the 1960s, faded after the 1965 discovery of the cosmic microwave background. Einstein himself believed in a static, eternal cosmos until Hubble showed him the expansion. The most prominent living challenger is bouncing, or cyclic, cosmology, pressed by Paul Steinhardt, the Einstein Professor at Princeton, and Anna Ijjas.

Steinhardt's role is unusual. With Alan Guth at MIT and Andrei Linde, then in the USSR, he is one of the three patriarchs of inflation — specifically of what was called new inflation. He now calls the theory baroque, pernicious, dangerous, and malevolent, not only for cosmology but for society. A robust consequence, Guth and Linde still argue, is a multiverse: inflation is hard to turn off, like a solid rocket booster, and keeps spawning universes. A theory that predicts everything, Keating says, predicts nothing. He will not deny Steinhardt's paternity or give the alternative extra attention because they are friends. He will take a founder attacking his own idea seriously.

The Soviet cosmologists who built inflation worked without Google Scholar, waiting for journals the Party had approved, some of them carrying passports stamped "Jew." Yakov Zeldovich could get a student travel papers only because he had standing from the atomic-bomb program. Fridman notes that the same system made scientists into public heroes. Keating's counterexample is Fritz Haber, whose Haber-Bosch process feeds much of the planet and whose chemistry also produced chlorine gas and Zyklon B. Some of Haber's relatives died at Auschwitz. Putting science above human dignity, he says, has been tried.

He calls himself a practicing agnostic: he does the things religious people do and does not do the things atheists do. Born to secular Jewish parents on Long Island, he went to synagogue twice a year. After the divorce his mother married Ray Keating, an Irish Catholic with nine siblings; Brian was adopted into that family, baptized, confirmed, and became an altar boy who could 2x the collection basket. At thirteen he ran the numbers. The next step was priest, and priests do not have relationships with women. The math did not add up. In the year he should have been preparing for a bar mitzvah, he got a telescope instead.

He still tells parents to buy a cheap refractor with a mount and a phone clamp. In Manhattan you can see the same lunar craters, Saturn's rings, and Jupiter's four moons Galileo saw. Sketch them. The Latin *educare* means to draw out, not to pour in. Then comes the academic hunger games: a faculty search at UC San Diego drew 400 applicants for one job. His father, the mathematician James Ax, had left and later turned from number theory to the foundations of quantum mechanics. Keating chose the foundations of the universe. The COBE satellite had just shown an anisotropy Stephen Hawking called the face of God. He wanted to be the person who understood what made the universe produce the signal — a closeted theorist, he jokes, the drummer who hangs out with the band.

The universe is 13.872 billion years old, known to about half a percent — the equivalent, Keating says, of looking at a fifty-year-old and dating him to within twelve hours. Twenty-five years ago the range was 10 to 20 billion, which was embarrassing because some stars looked 12 billion years old, older than their father. The number comes from the Hubble constant, a speed per distance: a galaxy one megaparsec away recedes at about 72 kilometers per second. Invert that, ignore a dozen nearby galaxies falling toward us, and you get the last time everything was touching.

The observable universe is larger than the age of the universe times the speed of light, because space itself has been stretching for 13.8 billion years and dragging photons with it. Light from the beginning can arrive from roughly three times that age, about 45 billion light-years in each direction, so the diameter of what we can see is around 90 billion light-years. Brooklyn is not expanding. The solar system is not expanding. What is expanding is the notebook on which the photons are written.

Empty a bottle outside a rocket, Keating says, and it is not empty. Every cubic centimeter of the observable universe holds about 420 photons left over from Big Bang nucleosynthesis, plus dark-matter particles, a scattering of neutrinos, and the occasional proton. A cubic millimeter holds 69. He wonders whether Elon Musk knows the number, and says Musk would enjoy it. Those photons are the film onto which primordial gravitational waves would leave a polarized imprint. LIGO cannot be parked at the Big Bang. The oldest light in the universe can.

BICEP — Background Imaging of Cosmic Extragalactic Polarization — began as a father-son rivalry Keating is not proud of. His father won prizes and never a Nobel; the Fields Medal is only for mathematicians under forty. He wanted a discovery for the ages. At Stanford he was a postdoc for Sarah Church, a new assistant professor studying high-redshift galaxies, while he sketched a different experiment. A friend, Mark Kamionkowski, now at Johns Hopkins, had pointed out that the inflationary signal is enormous on the sky. You do not need Hubble or a 30-meter mirror. A refracting telescope no bigger than a head would do.

He was a crappy employee. One day Jill Tarter, a SETI pioneer, visited Stanford and he asked for an introduction. Church said no — in fact, you're fired. It was, he says, possibly the best thing that ever happened to him. She recommended him to her former advisor at Caltech, Andrew Lange, a charismatic idea-man who had just measured, with the Boomerang experiment, that the universe is spatially flat. Take a blob of primordial plasma about one square degree across as the base of a triangle, the distance to Earth as the other two sides, and the interior angles sum to 180 degrees. The sky has about 44,000 square degrees. Hierarchical equal-area pixelization, HEALPix, came out of this field's early-2000s data analysis. Keating thought Lange was the next Eratosthenes. Before Lange finished offering the job, Keating took it.

They needed a place with as little water as possible, not as little heat. Microwave photons from the Big Bang sit at frequencies where water molecules resonate; put a cup in a microwave and the water boils while the dry mug can still be touched. Chile's Atacama, home of Keating's later Simons Observatory, and the South Pole are the two driest sites on Earth. BICEP went into the Dark Sector Laboratory at Amundsen-Scott Station, detectors cooled to 0.1 or 0.2 kelvin inside a vacuum chamber, tens of thousands of pounds scanning the sky almost unattended. Winter-overs arrive in November and leave the following December; the joke is $75,000 for one night of your life, a long night. Wisdom teeth and appendixes come out first. The nearest hospital is 4,000 miles away. At Russia's Vostok Station, 600 miles off, a doctor once photographed himself removing his own appendix.

In the studio Keating hands Fridman two polarizers. Stack them, rotate, and a light source goes bright-dim-bright-dim twice per physical turn. Polarization is the axis of the electric field; vertical and negative-vertical are the same state, so the pattern has spin-2 symmetry even though the photon is spin 1. Then he puts a calcite crystal on the printed notes. The text splits into two images — birefringence, two indices of refraction. Rotate a polarizer on top and the images trade places. That is the whole optical idea. BICEP moves it into the microwave, with superconducting bolometers at nearly a billionth of sea-level pressure, looking for a curl in the polarization map called a B-mode.

The cosmic microwave background itself was found by accident. In the 1960s Bell Labs hired radio astronomers to clean up the first communications satellites. Arno Penzias and Robert Wilson could not get rid of a hiss from every direction. A previous engineer, Edward Ohm, had measured the same three-kelvin excess and decided his error analysis was wrong. Penzias and Wilson built a four-kelvin calibrator — liquid helium, stable on a one-second cadence — and compared known against unknown the way a balance scale works only when the two pans are close. They measured 2.7265 kelvin. In 1978 they won the first Nobel Prize ever given in cosmology.

Radio astronomers quote signals as temperatures because that is what they are measuring. Keating likes the intimacy of it: life is a fight to control entropy, and here you are taking the universe's temperature. The B-mode they were after would be a few nanokelvin on a few-kelvin background, a part per billion. Penzias and Wilson's signal was a billion times brighter. Instrument sensitivity in this field has been doubling about every two years, outrunning Moore's law. Santa Clara's semiconductor fabs are clean rooms. The cosmos is littered with schmutz.

If Penzias and Wilson won for leftover heat, and Hulse and Taylor for an indirect gravitational-wave orbit, then seeing the initial conditions of the Big Bang looked like a stack of Nobels. BICEP2 swapped 98 semiconductor detectors for 512 superconducting transition-edge sensors: a superconductor's resistance falls to zero over a tiny temperature range, which makes an exquisite thermometer. In January 2010 the new receiver went onto the same South Pole mount. That same month, at Berkeley, Lange's thesis advisor Paul Richards told Keating that Lange had died by suicide. Keating had already lost his father. Lange had advised him on marriage, children, and the academic ladder. "I thought we were close. I told him everything. I felt like he had told me everything. Now he was gone."

Collaborators re-formed the leadership. Keating stayed a co-leader of BICEP1 and was no longer principal investigator or co-PI of BICEP2. Lange had been the only person protecting his place. Fridman reaches for a veterans' analogy. Keating prefers a band: the Beatles split over ego, credit, and solo careers. Science is an infinite game you cannot win, built out of finite games — one tenure slot, three Nobel names. The university dates to Bologna in 1088, and nobody taught him how to run a group or bury an advisor. His first thought, which shames him now, was that his own chance at the prize had died too. *Losing the Nobel Prize* is a double meaning: he lost it, and parts of it ought to be lost.

After the dust settled, the Royal Swedish Academy asked him to nominate the 2015 physics prize — the cycle in which he might have been eligible the following year. Of Alfred Nobel's rules, the letter kept one: you may not nominate yourself. He calls it the Keating correlation. Nobel wrote "one person"; the cap of three is a later patch that erases large collaborations. Barry Barish, who wrote a foreword for Keating, admits he won in part because another man died. The September 14, 2015, collision of two thirty-solar-mass black holes happened 1.2 billion years ago in an unknown galaxy. Had it arrived fifteen days earlier, before the nomination deadline, Barish would not have been on the list; Ron Drever was still alive. Hairless apes in fancy clothes handed other hairless apes a piece of metal in front of the King of Sweden, then ate reindeer.

Only when he wrote a book did Keating notice how ironic a dust jacket is. Cosmologists, he admits, look down on astrophysicists. They use Einstein, not Boltzmann, and study the largest picture, which is how you go blind to something obvious. Stars fuse hydrogen to helium and onward until iron. Iron fusion is endothermic: you put in more energy than you get out, the heat pressure vanishes, and the star collapses and explodes. Helium was named for Helios because it was first seen in the solar spectrum, not in a lab. The ejecta include iron and nickel. Some of it sank into Earth's core, some reached the crust, some your mother ate and turned into hemoglobin. The leftover grains, magnetized and aligned by the galaxy's magnetic field, act exactly like a polarizing filter. They turn unpolarized light into fully polarized light with a B-mode-like swirl.

On March 17, 2014, at the Harvard Center for Astrophysics, with three or four Nobel laureates in the room, the BICEP2 team announced it had seen inflation's aftershocks. Keating was still a member, no longer a leader; the first names after the opening thanks were his and UC San Diego's. He was not invited to the press conference. Max Tegmark tweeted, "Goodbye universe, hello multiverse." The team had not yet passed peer review. They feared an unethical referee would scoop them. Confirmation bias, Keating says, is a hell of a drug. Joint analysis with Planck later drove the primordial signal to zero. The paper was walked back.

He calls the pattern the science-media complex. Explosive claims land on the front page, above the fold, in the *New York Times*, the *Boston Globe*, the *San Diego Union-Tribune*. The retraction, six or twelve months later, is page C17 of the Saturday edition, under the personals. If he ever controls a large funding stream, applicants who budget for a press conference will have to post an equal bond for the retraction they hope never to need. The whole roller coaster is the science. Hiding the downslope, he argues, is how you cultivate the myth that Einstein walked out of the womb already Einstein.

Galileo is Keating's avatar, the logarithm of the all-around scientist he would like to approach — artist, writer, poet, philosopher, in an age when physician and physicist were still the same word. He was also wrong about as often as he was right. He backed Copernicus with evidence that did not hold. Tides, he said, were seawater sloshing because Earth both orbits and rotates; they are the Moon's differential gravity. He thought the Milky Way was only stars; it is also gas, dust, and nebulae. Proving that Earth orbits the Sun is much harder than proving it is round. Stellar aberration — tiny ellipses traced by stars because Earth moves at a non-trivial fraction of light speed — was measured in the late 1700s. CMB teams still correct for the same Doppler dipole: toward the motion the three-kelvin oven looks hotter, behind you it looks colder.

Keating is recording the first audiobook of the 1632 *Dialogue Concerning the Two Chief World Systems*, the book that put Galileo under house arrest. Carlo Rovelli reads Salviati, whose name means savior and who speaks Galileo's lines. Keating reads Sagredo, the intelligent middleman. A colleague, Lucio Piccirillo, reads Simplicio, the simpleton who recites the Pope. Frank Wilczek reads Einstein's foreword, Jim Gates the translator's note, Fabiola Gianotti Galileo's dedication to the Duke of Tuscany. Putting the supreme earthly authority's words in a character named Simpleton was not politically brilliant. He wanted an audio edition, found none, and decided to make one for Galileo's 457th birthday, February 15, 2022.

Another of Galileo's books is *The Assayer*. Court assayers rubbed alleged gold on a touchstone, a rock of no value that could certify a fortune. Keating's Assayer project would line up theories of everything and let data be the stone. There are too many such theories; he has joked that someone should get a Nobel for *not* proposing one. What he sees lately is retrodiction, not prediction: the LHC posts a result and string theory is suddenly compatible; the muon's magnetic moment misbehaves and a fifth force was predicted all along. Einstein retrodicted Mercury's perihelion after Vulcan failed as an unseen perturber — the same method that found Neptune from Uranus. Retrodiction is allowed. It cannot be the only move forever.

Keating names Eric Weinstein's geometric unity, Garrett Lisi's E8 theory, and Stephen Wolfram's physics project as ideas the field has not steelmanned. He cannot judge their mathematical beauty; he can see they are not being engaged. Weinstein works with extra time dimensions and objects he invented, from outside a faculty line, and met vitriol mixed with ad hominem. Keating gets the emails too: Einstein was wrong, I am bad at math, help me and we split the Nobel. Ray Dalio's rule is that an expert has done a thing successfully three times. Fridman pushes back: a track record in finance or cultural commentary does not transfer into physics. You still have to convince the people as obsessed as you are. "If you build a better mousetrap, the world will beat a path to your door" is false. You still have to sell the trap.

James Clerk Maxwell is the caution. In 1864 his unification ran on an ether, vortices, gears, and planetary machinery. Michelson and Morley would kill the ether a couple of decades later. Mock the components and you throw out equations that still run the world. Why, Keating asks, may Juan Maldacena calculate in anti-de Sitter space with five-dimensional wormholes — a universe we do not inhabit, through tunnels we do not know exist — and have Stephen Hawking concede the black-hole information paradox, while an outsider's equally indirect argument is a punch line? He does not have an answer. The field's nonsense detector is oversensitive. It stops a lot of spam and a few letters that might be right.

Among nine Nobel laureates in his book, only two theorists, Frank Wilczek and Sheldon Glashow, said they did not have impostor syndrome. Wilczek's result dates from the early 1970s; the prize came in 2004. Imagine being told you will win the lottery in thirty or forty years. Survival becomes the project. Keating's Assayer instinct is the opposite of waiting: find the low-energy test now. Newton split sunlight with a prism, recombined it, blocked orange, and showed color is synthesis — no collider required. Anytime an experimental physicist quotes a cost, double it, maybe triple it. Complex machines cost about ten percent of construction per year to run, so a decade doubles the bill. A future circular collider at $30 billion to build is $60 billion after operations. Then ask if it is worth it.

On the James Webb Space Telescope Keating can be a fan, because he is not competing with it for time, money, or people. Hubble's Ultra Deep Field put some 4,000 galaxies into a patch smaller than a tenth of a fingernail at arm's length, implying on the order of 500 billion galaxies. Webb is a single point of failure: twenty-two hexagonal mirrors unfolding a million miles from Earth, four times the Earth-Moon distance, with a sunshield and a downlink and no spare copy. Fail, and you lose not only $9.7 billion and twenty years but public faith that science can finish hard things. Guaranteed low-hanging fruit plus a swing for the fences is how he would spend billions. This, he says, is all fences.

On the table is a lunar meteorite. Apollo samples would make them felons; this one was blasted off the Moon, drifted in the Earth-Moon system, fell intact, was sliced, and arrived by USPS. Mars rocks sell the same way. If Mars can send stone to Earth, Earth can send stone to Mars, and if the stone carries microbes, panspermia is on the table. It explains how life travels, not how life starts. Meteorite speeds mean hundreds of millions of years even to a neighboring system, and the climb from bacteria to Bach does not have the time. Keating's back-of-the-envelope: eight hurdles — eukaryotes, oxygen, multicellularity, dinosaurs, whales, the rest — at one in a thousand each is 10 to the minus 24. The observable universe has about 10 to the 22 planets. He calls the 1-in-1,000 guess generous and still not optimistic. Lee Cronin will disagree, and Keating wants that debate, with love. Simple life, he thinks, is far more probable than a technological civilization. Those are not the same bet.

He has asked what would happen the day after we found life. His answer: nothing. Scoop Pacific water off San Diego and you already hold life, then watch the sewage and the toxic spill that closed the beach. In 1996 Bill Clinton announced possible microbes in an Allan Hills meteorite, a scene reused in *Contact*; later came claims of arsenic life at Mono Lake. We said "oh" and continued. A neighboring intelligence, he fears, would diminish the one religious claim he still holds: that every person has infinite worth. He does not believe in a bearded man in a chair. Sam Harris's line, that you cannot be happy, you can only become happy, he pushes through entropy: there are infinitely many ways to ruin a life and few to improve it, so invest in what would devastate you if it vanished. Parents love children more than children love parents, Aristotle said, because you love what you sacrifice for. Maxwell's equations in tensor form, riding on Einstein's, do not have to be beautiful to hairless apes. Maybe that beauty is a crack where the light gets in. He does not believe in God. He wonders whether God believes in him.