2010 marked the completion of a bizarre telescope composed mainly of ancient ice. One billion tons of ice.

Buried a mile deep in the ice at the South Pole, IceCube is the world’s strangest telescope. Composed of water, it’s looking for the neutrino, nature’s most unusual particle. Eighty years after the neutrino was “invented” to balance a physics equation, it remains ultra-difficult to detect, measure and understand.

IceCube is focused mainly on particles that come all the way through the Earth. In other words, this telescope looks down.

Scientists say neutrinos can pass unscathed through a long bar of lead. How long? Say, one light year long — about 10 trillion kilometers. Because neutrinos can slip through everything in their path, including stars, galaxies and vast clouds of dust, they are unrivaled tattle-tales of ancient explosions in the deep universe.

The bad news is that the same property makes neutrinos extremely difficult to see.

But if you can somehow observe the neutrino’s insanely rare interaction with matter, you could learn something about the universe, and the gargantuan energy released by exploding stars.

Roots of a frozen telescope

That is the promise and the premise of IceCube, a $271-million project intended to solve a problem posed in 1930, when physicist Wolfgang Pauli proposed a new and rather odd particle. Tiny, energetic, with no electric charge and not necessarily any mass, it would be virtually undetectable.

Pauli himself admitted “I have done a terrible thing. I have postulated a particle that cannot be detected.”¹

The “now-you-don’t-see-it-and-you-never-will” neutrino was tailor-made for controversy; scientists detest what they can’t detect. Pauli’s idea was mocked² as “simply wrong” or “crazy.”

Today, scientists are sure nature is full of these shadowy characters: Rough calculations say a hundred trillion neutrinos whistle through your body every second.

Why make a big deal about neutrinos, which are, after all, less offensive than campaign ads? Because that ability to pass through all manner of interstellar crud allows neutrinos to carry messages from the far reaches of the universe.

Moreover, some neutrinos carry more punch than the wildest gamma ray. And just as you can’t pull a hot coal from a cold fire, you shouldn’t get “hot” neutrinos from “cool” sources like ordinary stars. These neutrinos, in other words, may deliver signals of some hip, blazingly hot stuff — neutron stars, active galactic centers, and exploding stars.

Finally, according to some scenarios, lower-energy neutrinos may comprise a small proportion of the mass — the stuff — of the universe, but they played a key role in the evolution of the universe.

In astronomy, as in love and antiques, “hard-to-get” translates into “most-wanted.” “The hope is that the particle that is almost nothing will tell us almost everything about the universe,” says Francis Halzen, a theoretical physicist at University of Wisconsin-Madison. Halzen directs IceCube, and did the same at IceCube’s predecessor, AMANDA, the Antarctic Muon and Neutrino Detector Array.

Search strategy for an elusive character

Neutrinos may be shy, but once in a great while, they actually hit an atom and produce a subatomic particle called a muon, which is easier to see.

Because the odds of a neutrino hitting anything are so dismal, physicists require bigger targets. It’s the same principle that lottery players use to “beat” the tiny odds of winning by buying hundreds of tickets.

Previous neutrino targets have included tubs of oil or dry-cleaning fluid and 5,000 tons of steel plates salvaged from battleships. To block spurious signals due to cosmic rays rather than neutrinos, these detectors have been sunk in the ocean or placed inside deep mines.

IceCube relies on a two-step detection sequence: First, the tiny percentage of neutrinos that interact with atomic nuclei in the ice produce muons. Second, these muons create Cherenkov light when they interact with matter.

When the detectors see Cherenkov light, they digitize the data and send it through electric cables to the surface for analysis. The detectors are housed inside 5,160 crush-proof glass spheres placed in holes drilled through the ice, and located 1450 to 2450 meters deep.

Another 324 detectors at the surface detect muons made by cosmic rays arriving from the Southern sky.

The Antarctic ice also has little radiation, and the detectors are so deep that air bubbles have been squeezed out, ensuring great optical clarity. Yet while the detectors are shielded from damage, they are under crushing pressure, and if they go bad, they will be busted forever.

IceCube will only look at muons that trigger at least eight detectors, says Halzen, and is most interested in muons moving upward — coming from the Northern Hemisphere. Downward signals can be confusing, as most of them are due to cosmic rays or lower-energy neutrinos, which Earth blocks.

Data from IceCube should suggest where the neutrinos originated and what sort of cosmic engine started them on their journey.

This desire to concentrate on neutrinos rather than cosmic rays explains why this frozen telescope, oddly but logically, looks downward.

What can these neutrinos tell us?

Neutrinos, “invented” to balance a physics equation, have grown to fascinate astrophysicists, galactic voyeurs seeking signals from astonishingly energetic structures and events in the deep universe. The direction and energy of neutrinos from each source should offer clues about the origin:

Image: NASA/JPL-Caltech/STScI/CXC/SAO

Located 10,000 light-years away in the constellation Cassiopeia, Cassiopeia A is the remnant of a massive star that died in a violent supernova 325 years ago. The dead star (turquoise dot in center) became a neutron star surrounded by a shell of junk blasted away in the explosion. Image is a composite from three orbital telescopes: Infrared data from the Spitzer Space Telescope is red; Visible light from the Hubble Space Telescope is yellow; Chandra X-ray Observatory data is green and blue.

Although supernova neutrinos have low energy and are hard to detect, a nearby supernova could light up IceCube enough to overwhelm the system. To prep for a supernova, Reina Maruyama, an assistant professor of physics at University of Wisconsin-Madison, is working to ensure that IceCube can handle this once-in-a-lifetime chance to get good data on a stellar explosion.

If something like the 1987 supernova exploded nearby in our galaxy, Maruyama says, “there would be so many neutrinos, the whole ice would glow. We expect that a few supernovas will occur each century in the galaxy, if one goes off, IceCube has to be ready. We stand to learn a whole lot about how they explode, and about the particle nature of neutrinos.”

Dark matters

Even weirder than neutrinos, IceCube may explore dark matter, a type of, well, something, that comprises 23 percent of the overall universe. A measly 4 percent of matter, including the galaxies, stars and planets, is visible. The balance is an even stranger quantity called dark energy.

The first inkling that some matter is invisible came in the 1930s, when a physicist noticed that galaxies rotate too fast: their visible mass would create too little gravity, and thus they should spin themselves into oblivion.

The explanation for that increased gravity is now called dark matter, and the race is on to detect it.

Since dark matter affects gravity, Maruyama says it must gather in the sun and the galaxies. When dark matter particles collide, they are expected to release a type of neutrino called muon neutrinos. But IceCube found no muon neutrinos coming from the sun and the Milky Way, using a technique that was 1,000 times more sensitive than previous ones.

Does absence make the heart grow fonder?

It depends on your perspective whether that’s good or bad, says Halzen. “There was a big celebration when we published, because we placed limits on that particular type of dark matter, but I looked at it another way: We had gone 1,000 times deeper, and it was very disappointing not to see dark matter.”

However, an experiment in Italy may have seen dark matter interacting with a hunk of sodium iodide, based on an annual variation in the signal. If Earth indeed orbits through a cloud of dark matter, the detector would register alternating downstream and upstream motions that could account for that annual cycle.

The cycle could, however, be due to something unrelated to dark matter.

To answer that riddle, Maruyama wants to place a similar detector deep in the Antarctic ice, and has already piggybacked two prototypes onto IceCube strings. The prototypes are working well enough to justify a larger, more expensive detector, Maruyama says.

If and when the experiment is replicated in Antarctic Ice, Maruyama says, “A positive result would be interesting, and a negative result would be interesting. If we can see a signal with the same timing, that confirms the [Italian] results. If we don’t see a signal, the source must be something aside from dark matter.”

Lurking behind the IceCube project is the tantalizing prospect of learning more about the bizarre particle it detects — the neutrino. We already know that neutrinos have a tiny amount of mass, and that they range in energy through at least 30 orders of magnitude — an unimaginable range of energies. There have been recent — and controversial — reports that neutrinos can travel faster than light — breaking a basic law of physics.

Why so weird?

That’s another indication that neutrinos exist at the edge of the standard model that attempts to explain everything by gravity, electromagnetism, and two nuclear forces, Halzen says. “We are measuring the properties of neutrinos any way we can, and extrapolating to see what the standard model predicts, and looking for variations. The simple way to describe the experiment is that we collect muons and neutrinos, and everything you don’t understand is a discovery, either it’s physics beyond the standard model, or it’s new astrophysics.”

Halzen anticipates spotting an extremely high-energy particle called the GZK neutrino. “These are predicted by theory, and if one hits the detector, we won’t have to do any analysis, we will be able to look at the event display and know that we have made the discovery.” GZK neutrinos are, according to theory, made by cosmic rays that strike photons in the microwave background, Halzen says, and thus could finally reveal the origin of the cosmic rays, one century after their discovery.

Neutrinos are slippery characters; shy, coming in incomprehensible numbers, being emitted by sources we cannot pinpoint. Maruyama notes that neutrinos seemingly change to a different “flavor” without any apparent cause, and says this “oscillation” from one state to another is the strangest part of the neutrino story. “Oscillation could have implications on how the universe evolved to have matter, and not anti-matter,” she says. “These tiny particles could have such an influence on the universe.”

So what?

Why should non-scientists worry about neutrinos? Halzen, who has answered this question many times, says “I have a personal answer. The reason we know our place in the universe is not because of French philosophers, it’s because of physicists. With dark matter and dark energy, we know most of the universe is not made of the same material we are made of. … Is that important to know? I think so.”

IceCube is not intended to produce technology or solve today’s problems, Halzen acknowledges. “This is total curiosity-driven science, and you are allowed not to care. But if you don’t do fundamental research, we’re going to be a developing country, that is clear.”

Particle physics proves that theoretical pursuits can have results that are unpredictable, yet practical and profitable, Halzen says. “My previous job was at CERN [the European particle-physics lab], where people discovered the Web in 1989, to enable collaboration among remote scientists. I think we have paid for all theoretical physics with that one discovery.”

For advocates of space travel, the news is grim, and we’re not talking about the crash of a six-ton satellite last week, either. In July, the last U.S. space shuttle was parked, as planned. Over 30 years, the shuttles helped build the International Space, but two explosions killed 14 astronauts, and each flight cost nearly half a billion dollars.

On August 24, a clogged pipe caused the crash of a Russian Soyuz rocket. Soyuz is a reliable space-truck whose ancestor launched Sputnik, the first artificial satellite, in 1957.

With the shuttles in the old-age home, any delay of a Soyuz launch to resupply the space station, planned for Nov. 14, could force the station’s evacuation.

Abandoning the space station after a decade of continuous occupation might have limited scientific impact, as the station is not proving to be a scientific bonanza as promised. (However, on Sept. 21, NASA reported that a Japanese astronaut did perform “bubbling experiments” on green tea before staging a “traditional Japanese tea ceremony.”)

The growing problem of getting into space got more attention on Aug. 24, when a sub-orbital space taxi built by Blue Origin, a company funded by Amazon founder Jeff Bezos, crashed in West Texas, setting back the nascent space-tourism industry.

People have been going into space for 40 years, but the process is neither cheap nor routine. For comparison, 40 years after the first automobiles, millions of cars were changing the U.S. economy and landscape. And 40 years after Kitty Hawk (1903), airplanes had circled the globe and become a dominant force in World War II.

So, 40 years after Yuri Gargarin became the first space-farer, why is it so hard to get people into space?

It’s the gravity, stupid!

The first clue to the difficulty of reaching orbit is evident in the controlled explosion needed to launch anything: reaching orbit requires a speed of almost 18,000 miles per hour and overcoming gravity.

And gravity is a stern customer.

Although gravity is fixed, a changing political backdrop has deprived the space program of its historic justification, says Howard McCurdy, a professor of public administration and policy at American University, and student of the space program. “The key problem, as a political scientist, was the end of the Cold War. Now the rationale for a lot of human space program is jobs, but in the absence of Cold War competition, we get these anomalies,” like thumbing a ride to space from your former enemy.

Faced with the prospect of being stuck on Earth, on Sept. 14, NASA administrator Charles Bolden announced the Space Launch System (SLS), a heavy-lift rocket and space capsule designed to reach earth orbit and beyond. “American leadership in space will continue for at least next half century,” Bolden said. “We have laid the foundation for success.”

Better than nothing?

The reaction to SLS was a bit ho-hum. The proposal “has been controversial because some say it’s just the same old technology, a combination of Apollo, Saturn V, and the shuttle, and we really should be advancing the technology, doing something new that will get us to deep space more quickly,” says astrophysicist Jack Burns, who has served on the NASA Advisory Council science committee, and is vice-president emeritus for academic affairs and research at the University of Colorado System.

But what else is there? Burns asks. “I look at SLS as a practical vehicle that will get a lot of mass into orbit, and then to the moon, the asteroids. Having a heavy lift vehicle, for the first time since the mid ’70s, when we did away with Saturn V, should be an important part of U.S. space architecture.”

The shuttle, whose demise has forced the current concern over space launching, was hatched in 1972, by Pres. Richard Nixon, who proposed a reusable, flying bus to reach low orbit and “take the astronomical costs out of astronautics.”

Getting to orbit didn’t turn out to be cheap: NASA chalks up the average price tag on 135 shuttle launches at $450 million.

Consternation over Constellation

In 2005, faced with mission failures and an aging shuttle fleet, Pres. George W Bush called for the shuttle program to end after the space station was constructed. As a replacement, Bush proposed Constellation, a new rocket, and Ares, a new spaceship, which would visit the moon and then Mars.

However much the Mars mission was beloved by space-travel enthusiasts, it carries certain health hazards…

Cost estimates for Constellation and Ares rose faster than a rocket and by 2010, the projects had black-holed $9 billion, and the guesstimated price of launching a single Ares-1 had reached $1 billion. So Pres. Obama trash-binned the twin projects and directed NASA to come up with something cheaper and faster – which turned out to be the poetically-branded “Space Launch System.”

The proposal has, as we’ve said, met grudging acceptance at best. “This is a turning point for all kinds of reasons,” says Michael G. Smith, a space historian at Purdue University. “The shuttle program is finished after 30 years — it was too expensive, too old — and the Bush program to take us to the moon is finished.”

Although NASA has another job — the SLS — the manned space program needs goals with more focus, Smith says. Because Obama has failed to set a clear challenge before NASA, “they have nothing to prove, no short-term mission.”

In a sense, Smith adds, the Obama plan conforms to American desires. “There’s a paradox. A Gallup poll says the American public wants a space program, and is proud of it, but does not want to pay for it, and that’s the Obama Administration approach: ‘We want something, we have announced something, without a clear-cut commitment to what it is.’”

Take the money and … design?

In an era that is short of cash and jobs, however, NASA has an immense constituency in its legion of employees, contractors and their employees, Smith says. “Lawmakers with NASA investment in their districts are challenging the administration’s lack of clarity.”

But viewing a space program as a jobs program is unlikely to maximize either cost savings or scientific breakthroughs. “NASA has half-lost the ability to innovate,” says McCurdy. “People are hunkering down like turtles, protecting what they have, playing defense to hang onto the field stations [such as Marshall Space Flight Center in Alabama], and Congress is pushing them in ways that are inefficient for cost reduction. Most members want to know if contracts are still going to their districts.”

Space is inherently expensive, and McCurdy questions whether the current NASA budget will accomplish much space travel, or mainly rocket design and construction. “A big issue for NASA is whether the budget for exploration is going to be sufficient to actually develop, build and test the rocketry,” he says. “It looks like it will be sufficient to provide aerospace jobs, but they need a little bit more money to bend metal.”

Confronting costs

It’s odd, McCurdy says, that developing a new rocket and space vehicle are expected to cost $100 billion, considering that Saturn V, which launched Skylab and the moon shots, cost about $10 billion in 1960 dollars. “Multiply that by five to get today’s price — $50 billion — and that included the production line, a test vehicle and the actual rocket.”

Much engineering has been done for Constellation and previous rockets, and McCurdy, who acknowledges that the engineering and manufacturing expertise and the Saturn assembly line have long disappeared, wonders why NASA cannot produce a heavy-lift rocket for $50-billion.

Cutting the budget to the bone can be penny wise and pound foolish, McCurdy adds. “Once they got the assembly line going for Saturn V, it was very efficient, but if they build only one rocket every two years, it becomes more of a craft rocket.”

What are the other options for launching people into space?

Government rocket, private rocket

International rockets such as Ariane have gotten into the satellite-launch business, but most of them are not powerful enough to take people into orbit, or to leave earth orbit and reach the moon.

China, with one satellite orbiting the moon, and an imminent launch of an 8.5 ton component for its first space station, definitely has the lift capacity, but we’ve not heard about any discussions about launching U.S. space equipment.

Government is not the only game in town, however, and many hope that the genius of private enterprise will fill the gap, even if some of the efforts are watered with buckets of federal funds. If you place a challenge before rocket manufacturers, “both the startups and old horses, somebody may come up with a breakthrough,” says McCurdy. Even so, he adds, NASA must still “pick a winner before knowing whether it is a working design, and they are no better at that than I am at picking stocks.”

So how is the private sector faring in the human space travel biz?

the private role

Corporations are contending for two roles in space. Many are interested in space tourism, a business that began in 2001 with a seven-day visit to the International Space Station but today is focused on sub-orbital flights – spending a few minutes in micro-gravity beyond the edge of the atmosphere:

Photo: Jim Campbell/Aero-News Network

SpaceShipOne, built by Scaled Composites, slung beneath White Knight, the mother ship that lifts it toward the edge of space.

Blue Origin, a secretive operation funded by Jeff Bezos, the Amazon.com billionaire, is working on “New Shepard,” a sub-orbital vehicle. According to the website, “We’re working, patiently and step-by-step, to lower the cost of spaceflight so that many people can afford to go and so that we humans can better continue exploring the solar system. Accomplishing this mission will take a long time, and … we do not kid ourselves into thinking this will get easier as we go along.” Blue Origin has a NASA contract to develop a taxi for hauling astronauts to orbit, but recently lost a spaceship at 45,000 feet.

Scaled Composites, an advanced aircraft maker, won the $10-million X-prize in 2004 for attaining 328,000 feet twice within 10 days. The firm is working with Virgin Galactic to enhance its a sub-orbital spaceship-mother-ship combination. Virgin says 430 private-nauts are already put down a deposit for flights that will cost $200,000.

Xcor Aerospace is also selling seats on an unfinished spaceship, for a suborbital flight priced at $95,000, starting with a spare-change deposit of $20,000. Buy now, and your seat-mate could be a Victoria’s Secret model… Honest!

Let’s really go to space!

Above the sub-orbital realm, however, comes the real high-technology interest: resupplying the space station, or reaching the moon or an asteroid. In this realm, one company has grabbed most of the headlines: SpaceX, founded by PayPal founder Elon Musk.

SpaceX is developing two types of “Falcon” rockets, and has a $1.6 billion NASA contract to launch 12 loads of cargo to the space station (the first flight is scheduled for Nov. 30), in NASA’s Commercial Orbital Transportation Services program. (Orbital Science Corp. is the other contractor in the program.)

In December, 2010, SpaceX became the first private company to launch and recover a spaceship. “The technology has advanced,” says Burns, “but so far SpaceX only has a couple of launches of the Falcon 9. It’s a long way from that all the way to orbit, with real live astronauts. It’s a risky venture.”

SpaceX says it emphasizes reliability, and the business end of Falcon 9 houses nine individual rocket engines. The rocket is supposed to reach space even if one engine goes kaplooey.

A human role remains

When President Ronald Reagan proposed and promoted what is now called the International Space Station, a howl went up among scientists who called it a diversion of resources from the more productive unmanned spacecraft. Carting people around raises the price and the stakes at every stage of design, production and operation, and these scientists accurately forecast a fruitful program of robotic exploration — everything from the Hubble Space Telescope, to the Opportunity and Sojourner rovers on Mars to the Galileo spaceship that explored Jupiter.

Those robots were awesome and inspiring, says Burns. “Opportunity is U.S. technology, it’s something we all should be proud of it, it has well exceeded its lifetime, the engineers were very clever in the design and operation. That good old-fashioned American ingenuity ought to get kids excited about going into science, engineering, math, whether that gets directed to space or something else.”

The manned vs. robot argument had merit in its time, given that the space station alone has cost NASA north of $50 billion (with other countries contributing about the same amount), and NASA never has enough money for all the scientists who write grants, which leads some critics to question whether the money is well spent, or would have been more productive if spent on funding conventional science.

But the manned vs. robot dichotomy may be fading, says Steven Collicott, a professor of aeronautics and astronautics at Purdue University, who placed an experiment about the fluid flow in micro-gravity on the space station. “There is a great benefit to doing both. The astronauts who have operated space station experiments I have been involved in have been incredibly creative thinkers, problem solvers.”

The flow experiment cannot be performed on Earth, Collicott says. “We do everything we can to test on earth, or on short-duration, low-gravity [aircraft] flights, but there are times when … the camera position needs to be changed, or a liquid gets trapped. An astronaut can unbolt and shake the experiment … or act on their observations to explore a new phenomenon immediately, without reprogramming, relaunching or rebuilding, which involves years and millions of dollars.”

Human hands, eyes and brains are irreplaceable, Collicott says. “If people were not needed for research of this type, why would we be spending money to send people to Antarctica each year?”

human vs. robot — the dichotomy wanes

“I never felt comfortable with the manned versus unmanned argument,” says Purdue’s Smith. “We have always pursued both [approaches]. Satellite, probes and telescopes… There is no ICBM [inter-continental ballistic missile] system without satellites, there is no exploration of the moon or Mars without the [robotic] probes we have sent there.”

More on the manned vs. robot issue…

Yet despite the phenomenal allure of space-telescope photos, manned exploration plays a critical motivational role, Smith adds. “Without an orbital station, and the public interest and international cooperation that revolve around it, NASA can’t do anything. Satellites and probes just don’t drive that public interest.”

What Smith calls “fierce debates” between astronomers, who favor robotic exploration, and engineers who favor manned exploration are “not about policy or philosophy, they center on funding; those seem to me very parochial questions.”

Burns offers one suggestion for merging people and robots: sending astronauts to a low-gravity point above the far side of the moon (which never faces Earth), where they could control a moon rover. “Astronauts who are familiar with geological exploration could operate the rover in real time, there’s much less delay [in the radio signals]. They could visit the oldest [known] impact basin in the solar system, and it would not require a human lander, would be cheap, and would give you the kind of experience that is going to be needed” for further exploration of the solar system.

The quest to populate the solar system would entail a search for signs of life – and for water and useful minerals, Burns says. “This is going to require knowledge of geology, chemistry, astronomy and mechanical engineering; it will be very different than the first few flights to the moon that were just trying to get there. I argue that the difference between manned and unmanned travel is going to start to fade.”

Historic moment

Tele-operation, as remote-control is currently called, is being used every day by earthbound “pilots” in Nevada to fly drones in the Middle East, highlighting the firm link between space engineering and the military.

Rockets and satellites have military roots, and the space race was an early and intense focus of Cold-War competition, as the United States and Soviet Union both relied on German rocketeers who had helped the Third Reich try to conquer Europe. Now the United States and Russia, World-War II allies, then Cold-War enemies, have become allies once again, at least in terms of space cooperation.

Dating back to the late 1950s, Smith says, “Space policy has always been as much about perception as reality. It goes all the way back to the first ballistic missiles, the space race, the missile gap.”

John F. Kennedy warned about a “missile gap” while running for president, and even though it proved illusory, the fear of Soviet supremacy — Sputnik was in orbit while American rockets were exploding in front of TV cameras — supported the development of missiles that could be used for global nuclear war or putting men on the moon.

The result was lavish budgets for rockets and space.

But the easy goals have been reached, and visiting the moon is so last-century. Visiting an asteroid will answer important scientific questions, but will never have the sex appeal of visiting the man on the moon. As Smith says, today, “We are in another gap; an ambition gap.”

David J. Tenenbaum

How did galaxies form? It’s a cardinal mystery of the early universe. Microwave radiation created 380,000 years after the Big Bang shows a smooth array of molecules, spread out like a fog. The contrast to the situation one billion years later is complete: by then, matter was concentrated in stars and galaxies, separated by empty space.

Nowadays, most galaxies hide at least one super-dense black hole, whose gravitation prevents even light from escaping. Until now, nobody knew about black holes in the earliest galaxies.

Yesterday, Ezequiel Treister of the University of Hawaii and colleagues reported that most or all of the earliest galaxies also had black holes.

A problem of roots

The data illuminates the ultimate roots question – how our universe formed its present structure, and in particular, what happened during the billion years after the Big Bang banged about 13.7 billion years ago.

For 380,000 years, “During the embryonic universe, the fluctuations in density were about one-one thousandths of a percent, but over a billion years, structures developed,” Alexey Vikhlinin, author of a commentary in Nature, told The Why Files. “These galaxies are essentially the same type of objects in the present universe,” says Vikhlinin, an expert in X-ray astronomy at the Harvard-Smithsonian Center for Astrophysics.

How did we go from the primordial fog to a universe with ultra-dense galaxies, neutron stars and black holes separated by a vast nothingness where each cubic centimeter has about one lonely atom?

The vast epoch of ignorance, Vikhlinin says, “is called the dark age because little has been observed, and one of the major questions in astrophysics is how this transformation took place.” The new observations show that roughly the same proportion of matter (excluding the enigmatic dark matter and dark energy) was concentrated in galaxies and black holes then as now.

“These results show that pretty much every galaxy must have contained a substantial black hole, similar to today,” says Vikhlinin, “but this is the first observation that the relationship between galaxies and black holes that exists today, existed 1 billion years after the Big Bang.”

An extraordinary step

In the study, Treister and colleagues correlated long exposures from

Hubble Space Telescope, which can see extraordinarily distant (and ancient) galaxies, and

Chandra X-ray observatory, which picked up X-rays from distant, unidentifiable sources.

By pinpointing the source of Chandra’s X-rays on Hubble’s galactic snapshots, the scientists located ancient black holes inside some of the first galaxies.

The study benefited from three features, says Vikhlinin. “The necessary Chandra and Hubble data were taken only recently, and the observations were immediately made available to every interested scientist,” along with some money for their interpretation.

Treister also looked at the highest energy range that Chandra can detect, Vikhlinin adds. Because Chandra’s mirrors are more sensitive to lower-energy X-rays, “most people work in this region.”

The newly detected black holes produced a surprising result – that the basic structure of the universe has not changed terribly much in the 12.7 billion years since that ancient light embarked toward a planet that did not yet exist.

The “so-what?” part

Although the study shines some light on the presence of black holes and galaxies during the dark age, it does not provide a complete answer, says Vikhlinin. “It definitely seems as if galaxies and black holes have evolved in parallel. The growth of one controls the growth of the other, and vice versa, but the nature of the process and why they evolve in parallel is not entirely clear.”

Logically, a black hole would require a galaxy to provide the cold gas that it inhales. (This gas heats up as it enters the hole, creating the black hole’s X-ray signature; it also supplies material for the stars in the galaxy.)

But why a galaxy would need a black hole is less clear, Vikhlinin says. “We don’t know if galaxies can form in regions that initially don’t have the right conditions for the growth of a black hole. Maybe whenever a galaxy starts to grow actively, it makes a black hole in the center.”

Although the new evidence for an unchanging relationship between galaxies and black holes narrows the possible explanations, the formation of the first galaxies and black holes “remains one of the biggest unsolved problems in astrophysics,” Vikhlinin says.

– David J. Tenenbaum

On May 4, scientists announced success after a 50-year quest to measure two key consequences of Einstein’s theory of general relativity. The most perfectly round objects ever created by human hand, spinning aboard a spaceship launched in 2004, have detected infinitesimal disturbances in spacetime, the invisible fourth dimension of the universe:

To The Why Files, frame-dragging means that space is no longer flat, or even just warped. It is also twisted. And as a matter of principle, The Why Files likes twisted.

These consequences of predictions made in the early 20th century by history’s archetypal theoretical physicist are yet more proof that Einstein had it right, and are the latest chapters in history’s most compelling scientific detective story; which substantiated the highly theoretical speculation of a brilliant scientist through nuts-and-bolts observations of the universe.

Courtesy Eric Zuelow, University of New England

Is this tyke being “frame-dragged” in accordance with Einstein’s general theory of relativity, or is he just playing in a park in Kenilworth, England?

1905: Relatively special

In 1905, the same year he finished his Ph.D. thesis, Einstein published several amazing insights, including papers on Brownian motion and the photoelectric effect (the latter won Einstein his sole Nobel Prize). One of those papers proposed a theory of “special relativity” that said that the speed of light is fixed and independent of the observer’s motion. The 1887 Michelson-Morley experiment convinced Einstein that there was no ether (the supposed physical background that allowed light to move), and that the laws of physics were the same in reference frames moving with a constant velocity relative to each other.

Common sense says that a ball thrown from a moving car will move faster than one thrown by a person standing still – and still faster for someone in another car driving towards it. Common sense, Einstein proved, does not always apply. The speed of light does not depend on whether the light source is mounted on a Stanley Steamer, a space ship or a water tower. The speed of light is constant. And it doesn’t matter whence you observe it. Light speed is light speed. End of story.

Image: FL0

Using a device like this, Michelson and Morley found that light had the same velocity under different circumstances; a key stimulus to Einstein’s thoughts while working on special relativity.

1916: General relativity

Einstein’s theory of “general” relativity described how gravity affects space and time. Following his habit, Einstein started a thought experiment — a series of “what-if” questions – related to gravity: “If I were falling through space, I would not feel gravity.” Therefore, the laws of physics did not require gravity in every situation. But since the laws of physics must apply everywhere, then gravity must result from something else, which Einstein concluded was the fabric of spacetime.

The classic explanation for spacetime is this: gravity results when the curved fabric of spacetime causes a massive object (a bowling ball or a galaxy) to distort space-time, causing other objects to fall toward the “valley” it has created in spacetime. To us, this looks like gravity, but to Einstein, it’s more a matter of geometry.

1906: Working on the proof

One year after Einstein published special relativity, scientists got some support for the theory, says Richard Staley, an associate professor of the history of science at the University of Wisconsin-Madison. Einstein and others had predicted, for different reasons, that certain fast-moving electrons would gain mass. German physicist Walter Kaufmann did some experiments, and interpreted his results as proof that the mass gain was due to a competing theory rather than relativity, but “the tests were not accurate enough to make a decisive choice between the different theories,” Staley says.

1919: Sun’s gravity bends light

The first confirmation of general relativity appeared after a highly publicized journey by British astronomer Arthur Eddington. During a total solar eclipse, Eddington observed stars that were almost directly behind the sun. As predicted by general relativity, their starlight was bent by the sun’s gravity.

Gravity, counter to intuition, could bend light, and Eddington, no dunce, became an ardent popularizer of relativity.

Although we may look back on Einstein as an oddball with a zany haircut who stuck out his tongue and rode a bike, he was a serious man who thought about politics as well as physics. Living in Germany during World War I, he was an outspoken pacifist who organized scientists against militarism. “Einstein thought we needed to think across national borders and tried to start a book project to include contributions from people from neutral and enemy countries,” Staley notes. “Most of his colleagues said it was a great idea, but would be counterproductive. They refused to participate, so it did not happen.”

Even before his fame got a boost by the 1919 confirmation of relativity, Einstein was willing to “take stances counter to others,” Staley says. “He was cautioned about going public, but when the war was finished, he decided he’d been right. Even though physics does not give you a particular insight into politics, it was clear that nobody had better insights, so he might as well make his views public.”

1974: Neutron stars and gravity waves

By the 1920s and ’30s, relativity was enshrined as a foundation of physics, but the proofs rolled on. In 1974, researchers found that a pair of neutron stars — phenomenally dense objects formed after regular stars collapse — was losing energy. Neutron stars emit extremely regular radio pulses, and the slowing of the pulses was interpreted to mean they were losing energy through the gravitational waves that general relativity predicts. The discovery won the 1993 Nobel Prize for physics.

Detecting gravity waves remains the object of an expensive, long-term scientific quest.

1979: One weighty lens

In 1936, three years after Einstein emigrated to the United States to escape the Nazis, he predicted that immense gravitation would bend light rather like a lens. Contemporary telescopes were unable to find such a “gravitational lens,” but in 1979, astronomers noticed two surprisingly similar images of a distant quasar and concluded that they were looking at a double image of one giant light source, split in two by a cluster of galaxies along the sight path to Earth.

“As usual, Einstein was ahead of the curve,” Harvard historian of science Gerald Holton told The Why Files in 1997. In 2006, a single quasar appeared in five individual images, again due to the gravity of an intervening cluster of galaxies.

Apparently a trillion stars, more or less, will do strange things…

1997: Neutron stars and frame-dragging

Although the 2011 report from Gravity Probe B was the first to identify “frame-dragging” of spacetime due to Earth’s mass, in 1997, scientists reported that rotating black holes and neutron stars were frame-dragging. The study, by Wei Cui at Massachusetts Institute of Technology, found that the gravity of a black hole spinning several thousand of times per second was distorting spacetime into a funnel shape. “It’s a very abstract thing,” Cui told us.

Black holes are extraordinarily dense points in space with a super-intense gravity that even traps light. Their presence can be deduced from a shower of X-rays produced as matter falls into the hole.

Scientists have long accepted that massive objects distort spacetime much as a bowling ball would distort a web of fabric that supports it. But frame-dragging means a rotating mass has some “sticky” quality that drags spacetime, and frame-dragging was more proof that Einstein was right, Cui said. “These are all results of his theory of general relativity, which described gravity.” In other words, gravity becomes a property of spacetime. “You can take all the facts of gravity and explain them with a certain geometry of spacetime.”

1995: The ultimate chill-out

Back in 1925, when “automobile” meant model A, and “president” meant “Silent Cal” Coolidge, Einstein predicted that a strange phase of matter would exist near absolute zero, a frosty -273°C. Expanding upon the calculations of Indian physicist Satyendra Nath Bose, Einstein calculated that atoms would enter a unified quantum-mechanical state near the coldest possible temperature.

The atoms would become a drill sergeant’s dream — identical in mind and body.

What was dubbed the “Bose-Einstein condensate” would also be a new phase of matter. Since only four phases exist in the universe — gas, liquid, solid and plasma — discovering another phase would pump up a resume.
In 1995, Carl Wieman, a professor of physics at the University of Colorado, and colleague Eric Cornell fulfilled Einstein’s prediction by creating this bizarre phase of matter at just 200-billionths of a degree Celsius above absolute zero. As Wieman told us in 1997, “We wanted to see if real atoms could ever match the ideal system that Einstein was considering, and they did match — really quite nicely.”

Quantum mechanics says that atoms can exist in certain energy states, but not in between. A group of atoms occupies numerous energy states, washing out the quantum-mechanical effects, but in a Bose-Einstein condensate, Wieman said, “You have a bunch of atoms in a single quantum state, obeying the laws of quantum mechanics as a whole. Traditionally, to see a quantum state, you had to look inside a single atom. Now we can look at millions of atoms.”

2011: Sweet success smiles on Gravity Probe B

The insights of the former Swiss patent clerk are impossible to exaggerate, but it took a lot of technical sophistication and ingenuity to detect disturbances in spacetime in the vicinity of Earth. That was the goal of Gravity Probe B.

Francis Everitt, a Stanford University physicist who has devoted his career to sailing Gravity Probe B across technological and financial shoals, compares the “dragging” of spacetime to a giant pot of honey. “As the planet rotated its axis and orbited the Sun, the honey around it would warp and swirl, and it’s the same with space and time.”

Save for the effects of gravity and relativity, the high-tech gyroscopes aboard the spaceship should point forever in one direction. Instead, gravity changes their orientation in subtle but measurable ways.

The rotors in those gyroscopes are the most precise spheres ever manufactured, which is astonishing if you consider that they were measured with “micro-inches” rather than microns.

It is not necessary  to offer a practical justification for a proof of relativity – simply explaining the universe is ample. But Gary Shiu, a professor of physics at the University of Wisconsin-Madison, notes that the ultra-precise equipment crafted for the gravity probe helped improve global positioning systems and the gizmos used to map the microwave background radiation that was created shortly after the Big Bang and still pervades the cosmos. “These technologies have already been developed, the spinoff already proven,” Shiu says.

Although some of the previous proofs of general relativity could conceivably be explained with alternate theories, Shiu says, “The frame-dragging detected in Gravity Probe B provides yet another independent test that any alternative to Einstein’s general relativity would have to meet.”

A man apart

A theory must explain the working of some aspect of nature, and it must be tested, generally by trying to disprove its predictions. Does your theory say gravity is an attraction between any two objects? Then, if you can find objects that fail to attract, you need to revise or reject your theory.

After a century of confirmation of Einstein, the obvious remaining question concerns scientific creativity rather than physics: What was Einstein’s secret? “He was very persistent, was the prototypical scientist,” says Shiu, who helped organize an upcoming conference on Cosmology since Einstein. “When he wanted to solve a problem, he could take 10 or 20 years. We cannot figure out the answer in a few months or years, we need to do whatever it takes to solve the problem.”

Kip Thorne, a California Institute of Technology physicist, told us in 1997 that he attributed Einstein’s deep insight to his “conviction that the universe loves simplicity and beauty… His willingness to be guided by this conviction, even if it meant destroying the foundations of Newtonian physics, led him, with a clarity of thought that others could not match, to his new description of space and time. … All new laws that have been successful in describing the real universe have turned out to obey Einstein’s principle of relativity.”

Indeed, Thorne called relativity a kind of super-law that “must be obeyed by all laws of physics, no matter whether they are laws governing electricity and magnetism, or atoms and molecules, or steam engines and sports cars.”

Gerald Holton, a physicist and historian of science at Harvard University, pointed to several characteristics that helped Einstein ^{1 2} excel:

Beyond a unique ability to peer inside the universe, Holton says Einstein also wrote about his philosophy and technique. “This man allowed himself to be more public and frank, and in particular about his scientific method, which is very much the method still used by other physicists.”

Yet for all his brilliance, Einstein failed to find the holy Grail of physics –a “grand unified theory” to explain all four physical forces. Electromagnetism and the strong and weak nuclear forces are explained by a single theory called the “standard model,” but to this day, gravitation stands stubbornly apart.

Summing up? Einstein

Einstein’s revolutionary theories grew from his philosophy of nature and insistence that physical laws must be true on Earth, space ships and stars, combined with a phenomenal intuition for nature and enough self-confidence to rewrite Newton’s laws of gravitation and motion. Einstein interpreted experiments from the 1880s, which suggested that the speed of light was independent of the observer’s motion, as meaning that the speed of light is constant throughout the universe. He then proposed that mass would affect light and spacetime, which is the backdrop for all events, atomic, human, cosmic and comic.

Still, everybody makes mistakes. Einstein denied the existence of black holes and loathed the role of chance in quantum theory, saying “God does not play dice with the universe.” He also cooked up a “cosmological constant” because his theories implied that the universe was changing size, which he considered too weird to be true.

When astronomer Edwin Hubble proved that the universe was expanding, Einstein called the cosmo constant “the greatest blunder of his life.” And yet recent discoveries indicating that the universe is, for unknown reasons, expanding ever faster could mean that his “greatest blunder” was not that far off…

Although Newtonian physics still describes what we see every day, more than a century after the young patent clerk brutally shouldered Newton aside, there’s no question Einstein grasped the big picture. And that returns us to this simple question: “How did he do the things he did?”

“Einstein was typically working between several different theoretical approaches,” says Staley, the science historian. “He was looking for places in which the best laws we currently have fail or don’t provide clear guidance, and then was trying to use those critical gaps to provide new insight into connections between different areas. People often think he thought outside the box. I think he thought across several boxes, and saw ways to link theory that others did not recognize. Although others were also looking at the limits of theory and trying to unify different areas, he did it better.”

 

Photo: NASA

The Crab Nebula was made by a supernova that was seen in China and the Middle East in 1054. The clouds of dust ‘n debris created by supernovas continue to expand for thousands of years. For a better look, go to NASA’s animation.

These starbursts produce a gargantuan flash of light and energy that may briefly outshine the star’s home galaxy. In its aftermath, a supernova may leave a super-dense neutron star or a black hole, surrounded by an expanding nebula of dust and gas.

Larger stars tend to produce larger supernovas. One of the largest on record was detected in 2007, when a star roughly 200 times as massive as our sun went kaput.

A supernova is triggered by an imbalance between the inward force of gravity and the outward force exerted by the star’s energy production. A star can simply run out of hydrogen and helium fuel, and collapse as nuclear fusion slows and gravity overcomes the fading outward pressure. Stars with 10 to 140 times the mass of our sun may have iron cores that can collapse, forming a supernova and leaving a neutron star in its wake.

 

Photo: NASA

Supernova 1987A formed from the collapse of the iron core of a giant star. Larger stars, which produce a larger supernova, have an oxygen core. Those “pearls” at the ring show that the explosion is contacting a pre-existing ring of gas.

Second biggest bang?

A more exotic process can create stupendous explosions in humongo stars with more than 140 solar masses.

This week, Nature published a study by Avishay Gal-Yam, of the Weizmann Institute of Science, in Rehovot, Israel, of supernova 2007bi, a mammoth explosion located 1.5 billion light years away. The explosion, one of the largest ever seen, was observed by multiple large telescopes and released 10 ⁵³ ergs of energy. According to our calculations, that’s as much energy as our sun would release in almost 1 trillion years!

The march of superlatives continues: spectral analysis shows that the explosion coughed up 50 to 100 solar masses of heavy elements, such as carbon, oxygen, sodium, magnesium, calcium and iron. The debris included 3 to 10 solar masses of nickel.

Immediately after the explosion, this huge pile junk was departing scene at 12,000 kilometers per second.

That’s rapid transit, in our book. And it’s another example of the fact that the heavy elements in the universe – essentially every element more massive than hydrogen and helium – was formed inside stars.

As Carl Sagan once said, “We are all star stuff.”

The explosion was the first convincing example of a theoretical phenomenon called pair instability, says Gal-Yam, who points out that many measurements of the actual supernova matched predictions made by theorists. In the insanely hot (1 billion degrees Kelvin) core of this heavy star, energetic light particles, called photons, are converted into pairs of electrons and positrons, the electron’s anti-matter counterpart.

 

Photo: NASA

The Keck I telescope was used to investigate the giant supernova explosion. This rotating base supports each of the two Keck telescopes in Hawaii.

A loss of equilibrium

The electron-positron pair quickly annihilates itself, making more photons, which make more electron-positron pairs. But if the pair is present only for an instant, and it releases energy as it self-annihilates, how does this cause the star to collapse? It’s all a question of balance, says Gal-Yam. “At any time, you have transformed some photons into electron-positron pairs, which is enough to take away some fraction of the energy. The star was at equilibrium before this process, the pressure of the energy and gravity were balanced.”

 

Image: jpockele

Computer chip contain silicon in the microprocessors, aluminum and copper in conductors, and gold in the connectors. How cool is this: When astronomers study stars with computers, they are employing elements created in ancient star explosions!

But converting the energy in photons into the mass of electrons and positrons disturbs the equilibrium. “Each particle may not live a long time, but there are always some particles taking away some energy, so it goes out of equilibrium, and the core begins to contract,” Gal-Yam says. “When this gets severely out of equilibrium, the inertia of the infalling material, moving under gravity, will cause the oxygen core to start to fuse into heavier elements. Runaway fusion begins, and you get the big explosion.”

We’ve spent our supply of superlatives, but these jumbo explosions could be a source of gamma ray bursts, the brief showers of gamma rays that must originate in hideously strong astrophysical sources.

A done deal?

“My gut reaction is that this probably is a pair-instability supernova, and that’s pretty exciting,” says Richard Townsend, professor of astronomy at the University of Wisconsin-Madison, but he says the argument is not yet “watertight.” A previous claim for a pair-instability supernova has faded, he says, because it appears that some of its energy was made by the ejected material that blasted into stuff that the star had previously coughed up, called circumstellar material. “If ejected material plows into circumstellar material, radiant energy can be produced to augment the radiated energy of the actual explosion, making it appear more energetic.”

 

Photo: Conan Lang

This ornate copper metalwork was made in Tibet in the 16th century. Did the artists knew their materials were formed in star explosions?

Townsend, who studies the evolution of stars, says “The authors’ basic claim is that because there is no evidence for interaction with circumstellar material, the only alternative is a pair-instability supernova, yet the paper contains no direct evidence” for pair instability. “It’s more that this is the only option left standing once they have ruled out other choices.”

The existence of super-massive stars, much larger than those seen today, would help explain events during the first billion years of the universe, Townsend adds, and finding such a star in the “modern” universe could be key to understanding how the ancient universe developed into the one we see today.

Speaking selfishly, the pair-instability supernova could be a major source of 90 of the 92 elements that are found in nature, which astro-types call “metal.” Otherwise, the universe would consist largely of a boring mix of hydrogen and helium. No cars, no telescopes, no paychecks. Not even pay-per-view TV.

An unstable pair

It’s too soon to say how much of the metals originated in pair-instability supernovas. “We have measured what the explosion made,” says Gal-Yam, “and theory predicts how much will be made, but we don’t know how common these explosions are. If they are very rare, then there’s not much of a contribution. If they are less rare, they might be important.”

A series of new telescopes that can quickly identify fast-changing light sources should provide a more examples of these titanic supernovas, and help determine their role in seeding the universe with the elements in our planet and our bodies.

David J. Tenenbaum