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: Fiorenzo Omenetto

But you sure can copy her. That’s an engineering approach called biomimetics – the quest to exploit the three billion-year evolutionary process that has perfected structures and materials as strong, spare and sophisticated as the hawk’s eye and mother-of-pearl.

Now we read about progress in the effort to make artificial silk – the light, ultra-tough fiber produced by spiders and silkworms. Like plastic, silk is a polymer – a series of repeated structures that can be altered to produce different results.

But unlike plastic, the sub-units in silk are proteins. And silk can’t be made in the lab – yet.

In fact, it’s not yet clear how silk is made inside silkworms and spiders. As silk is forming, its proteins are so dense that they should glom together before the animal can spin the silk fiber.

Because a glance at a spider’s web proves that silk is possible, biologists and engineers are exploring the chemistry and physics of silk production.

By controlling the acidity and flow of the liquid pre-silk, and using mechanisms that are presently mysterious, spiders and silkworms create a fiber that shames even Kevlar, the fiber that is blended with polymer for lightweight canoes and bullet-proof vests.

Strong, ‘n silky?

In terms of tensile (pulling) strength, silk approaches high-tensile steel, and is one-quarter as strong as Kevlar. But if you bend Kevlar, it “will fail immediately,” says David Kaplan, a professor of biomedical engineering at Tufts University.

In contrast, silk excels in a quality called toughness – the Rambo factor, which combines tensile strength and flexibility. “Silk is really good at tensile strength and toughness, and you can’t emulate that with a synthetic material,” Kaplan says.

Silk has many other desirable properties, adds Kaplan, co-author of a review on silk technology being published in tomorrow’s Science. The silkworm’s silk cocoon must protect the developing moth against rain and other environmental perils, yet the moth must digest the cocoon as it emerges.

Silk can also be highly elastic. “To catch prey, the spider can throw the silk like a lasso, and it sticks so the spider can reel the prey back in.”

Courtesy of what Kaplan calls “a glue-like feature that holds the fibers together through a protein-protein interaction,” spider-web silk can also adhere to itself, and to vegetation.

Because spiders and silkworms are only distantly related, the genes for silk must have evolved several times, Kaplan says. “That’s a vote for the simplicity and utility of the system, which clearly provides an important survival function.”

Finally, these remarkable materials are made with the ultimate green chemistry, with neither heat nor toxic byproducts, and using only water as the solvent.

Medical miracle?

Silk has been used for surgical suturing since Egyptian times. But Kaplan and others envision using this ultra-tough, biodegradable material as a

* scaffold to hold stem cells to regenerate diseased tissues, such as bone, kidney and cartilage;

* container to introduce cells, drugs or growth factors; and

Photos: University of Akron

For sheer toughness, spider silk trumps such synthetic fibers as carbon fiber and Kevlar.

* an injectable goop of silk precursors and the appropriate drugs or cells which would transform into a gel state and deliver its cargo before slowly degrading.

In 2009, Serica Technologies, Inc., got Food and Drug Administration approval for a silk-based material to be used as a supportive mesh in soft-tissue repairs. (Serica has since been acquired by Allergan, Inc.)

If silk is so slick, can it be made in larger quantities with traditional, in-glass chemistry? Perhaps, but Kaplan is more excited about moving the silk genes into plants or animals, so biology can make the precursors, or possibly a finished silk fiber.

As mentioned, the study of silk illustrates how engineers can be inspired by biology. Seventy-five percent of silk is composed of just two amino acids, Kaplan says, yet “this material is unique. It can make incredibly strong, tough, interesting materials, and do it through a green process. I can’t imagine where you can get more interesting properties from a simpler system.”

David J. Tenenbaum

Whether it’s beer or soap, soup or suds, bubbles are a fact of life. These evanescent but ubiquitous structures posed a perfect challenge for James Bird, who has just received his PhD from Harvard University. “Bubbles are fun, but the dynamics are fast enough that you have to use high speed cameras, and the visual aspect appeals to me,” Bird says.

Bubbles matter in realms ranging from medicine to climate. But until now, nobody knew that when larger bubbles break, they spawn smaller bubbles. Even stranger, as Bird and his graduate advisor Howard Stone, who is now at Princeton University, have found, these “daughter” bubbles can even spawn “granddaughter” bubbles.

This chain reaction only occurs when many factors, like bubble size and liquid viscosity, are correct.

Suitably, Bird says the bubble study arose when he and co-author Laurent Courbin were “playing in the lab late one night, trying to get a bubble to spread on different surfaces, but instead this hemispheric bubble would pop to create a ring of daughter bubbles. We looked at each other and were not sure what was going on.”

As Bird recalls, “Howard gave me permission to have fun and see if I could figure it out.”

Tense at the surface

The major physical force at work in the bubbles is surface tension – the same phenomenon that causes water to creep up the side of a glass. Surface tension occurs because smaller surfaces have lower energy, so stretchy materials like films and balloons tend to adopt a shape with the smallest area.

Surface tension forms spherical bubbles because spheres have the smallest area for any given volume of fluid. But surface tension also exerts pressure on the trapped gas, which explains why bubbles pop rather than just break.

Courtesy James Bird

After a bubble breaks, the retracting liquid may form a lip that traps a donut of air. This donut is the origin of tiny “daughter bubbles” that can break and form yet another ring of “granddaughter” bubbles.

Using high-speed video, Stone, Bird and their colleagues popped a bubble and watched it break. As the trapped gas rushed out, surface tension retracted the bubble film, and a lip formed around at the top. “If you apply force to something, it tends to move in straight line,” says Stone. “When the soap film pops, surface tension pulls to open the ring, so the film moves in a horizontal line at first.”

Meanwhile, the absence of the internal pressure causes the rest of the bubble to implode. The combination of these two motions creates a tiny lip at the top of the bursting bubble. As the bubble retracts, the lip curls over and briefly traps a donut of air around the bubble.

From that point, says Bird, “It’s 19th century physics. The daughter bubbles form for the same reason that a faucet jet breaks up into little droplets.” Translated: The droplets have a lower energy state than the stream of water, and the daughter bubbles have a lower energy state than the donut of trapped air around the broken bubble.

Chain reaction

The formation of “daughter bubbles” is not the end of the story, however: when they land on the liquid, they may also break up, forming a third generation of bubbles.

When a bubble pops, a jet of material may rise at the center. In a big bubble, these jets remain at the surface, but the higher pressure in a tiny bubble will squirt a smidgeon of liquid, together with any associated chemicals or particles, into the air.

The “bubble-begets-more-bubbles” phenomenon could matter, because these jets can carry pathogens and spread disease in hot tubs or swimming pools.

And a ridiculous number of bubbles — between 10¹⁸ and 10²⁰ — supposedly break every second in the oceans. These bubbles can carry heat, chemicals and water vapor into the atmosphere, affecting weather and climate.

Computerized climate models must consider the interaction between ocean and atmosphere, which entails accounting for all these breaking bubbles, Stone says. “If you don’t know these parameters, your model is filled with ad hoc parameters [AKA wild guesses] and you don’t even know the order of magnitude. Computer models are only as good as the parameters that go into them.”

Small is beautiful

By showing how large bubbles create a cascade of smaller bubbles, the new study highlights the real-world effects of large bubbles, says Bird. “People have discounted bubbles bigger than a few millimeters because they did not create aerosols, but we think the impact is actually much greater because the bigger bubbles are a source of lots of little bubbles, which can make a lot of aerosols.”

And the answer to your inevitable last question is yes. Bird “absolutely” did play with soap bubbles as a kid.

David J. Tenenbaum

Photo: audi_insperation

To young people, bubbles are nearly irresistible!

 

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