This might not sound like the secret to interstellar travel, but if that small lurch can be sustained, a spacecraft could theoretically produce thrust for as long as it had electric power. It wouldn’t accelerate quickly, but it could accelerate for a long time, gradually gaining in velocity until it was whipping its way across the galaxy. An onboard nuclear reactor could supply it with electric power for decades, long enough for an array of MEGA drives to reach velocities approaching the speed of light. If Woodward’s device works, it’d be the first propulsion system that could conceivably reach another solar system within the lifespan of an astronaut. How does it work? Ask Woodward and he’ll tell you his gizmo has merely tapped into the fabric of the universe and hitched a ride on gravity itself.

Sound impossible? A lot of theoretical physicists think so too. In fact, Woodward is certain most theoretical physicists think his propellantless thruster is nonsense. But in June, after two decades of halting progress, Woodward and Fearn made a minor change to the configuration of the thruster. Suddenly, the MEGA drive leapt to life. For the first time, Woodward seemed to have undeniable evidence that his impossible engine really worked. Then the pandemic hit.

Woodward turns 80 next year. He is a survivor of stage IV lung cancer living with COPD, and he is being treated for relapsed Hodgkin's lymphoma. That puts him in the high-risk category for Covid-19, so when cases in California started climbing, he grudgingly left his lab at Fullerton and hunkered down at home. But he wasn’t going to let a global pandemic stymie his progress.

Over the summer, Woodward gradually turned the office he shares with his partner, Carole, into a den that would be the envy of any mad scientist. Hand tools are scattered around Woodward’s desk among boxes full of new ball bearings, stacks of crystalline disks, and scraps of metal shim that Woodward has cut into electrodes. There’s lubricant that costs $175 a bottle, for greasing the bearing rods, and a special glue that has a number for a name. It’s a stark contrast to Carole’s neat desk on the other side of the room, but Woodward says she’s so far tolerated his ad hoc thruster factory. “I should think that having a partner like me would be very trying,” he says. “She has been astonishingly good about it over the years.”

Woodward built a dozen or so devices and handed some of them off to Fearn, who tested them in their shared lab at Fullerton. Later this fall, they’ll send a device to an independent researcher in Toronto named George Hathaway, an experimentalist with ties to NASA whom Woodward described as “probably the finest experimentalist in the world for this type of work.” Woodward prepared another thruster for the US Naval Research Laboratory, which will also try to replicate the duo’s results.

The amount of thrust Woodward appears to have coaxed out of his MEGA drive is tiny even compared to the puniest satellite thrusters in orbit today. But if other engineers can confirm his results, it could be our best bet yet for a human mission to the stars.

SCIENTISTS HAVE LONG dreamed of seeing an alien sunrise. Our sun is just an average star, one of billions like it in our galaxy. Many of those stars also have planets, some of which might have the right conditions to support life. In 1911 the Russian scientist Konstantin Tsiolkovsky, generally regarded as the father of rocket science, was the first to outline how an interstellar spacecraft might go about exploring them. Since then, scientists have proposed using fusion engines, wormholes, massive lasers, and hydrogen bombs to whisk humans across the deepest of deep space.

Only two spacecraft—Voyager 1 and Voyager 2—have ever entered interstellar space. Like every spacecraft to date, they were hurled into the void by a rocket and then used small liquid-fueled thrusters to navigate the solar system. They’re now booking it through the cosmos at more than 35,000 miles per hour. NASA has contemplated an uncrewed interstellar mission for years, but the only one under active development today is an independent effort called Breakthrough Starshot. It aims to use exceptionally powerful lasers to propel a spacecraft the size of a fingernail up to 20 percent the speed of light. For humans to make the trip, they’d need a much larger craft—and a propulsion system that, ideally, could get them there within a generation. That species-defining challenge was what captivated Woodward as a young man.

Woodward was born in Boston in 1941, the eldest son of a patent lawyer and an astronomer. His mother, the astronomer, gave him a basic fluency in the language of the universe and stoked his curiosity about the cosmos. As a child, Woodward tinkered with homemade rockets, but he didn’t get very far. His younger brother, Paul Woodward, an astrophysicist at the University of Minnesota, recalls a time when his older brother pilfered potassium nitrate from his childhood chemistry set and used it to make a homebrew rocket that exploded spectacularly over their neighborhood.

“The story was that my father got on some sort of list for doing that and could not buy me any more chemicals for my experiments,” Paul recalls. “So the launch was the end of Jim's career in rocketry and my career as a chemist.” Still, Woodward followed his childhood interest into a physics undergraduate program at Middlebury College, a small liberal arts school in Vermont. But it was an experience he had a few years after graduating that changed the course of his life.

On a clear night in March 1967, Woodward was stargazing on the rooftop of Pensión Santa Cruz, a hotel in the heart of Seville, in Spain. The 26-year-old physicist was struggling with his chosen profession and had taken a break from graduate work at New York University. He found himself drawn to fringe research topics, particularly those having to do with gravity, which he knew would make it hard to get a job. “It became clear to me simply by looking at the physics department around me that a bunch of people like that were unlikely to hire someone like me,” Woodward says. So he decided to try something else. He had picked up flamenco guitar as an undergrad and even performed in clubs in New York. Inspired by his aunt, a CIA officer who had learned to play the instrument while stationed in Madrid, he headed to Spain to pursue a career in it.

At the time, the space race was only a decade old and satellite spotting was a popular sport. As Woodward gazed up from atop his Spanish hotel, he saw a speck of light arcing across the sky and mentally calculated its path. But as he watched the satellite, it began deviating from its expected trajectory—first by a little and then by a lot.

Everything Woodward knew about satellites told him that what he was seeing should be impossible. It would take too much energy for a satellite to change its orbit like that, and most satellites weren’t able to shift more than a couple of degrees. And yet, he had just seen a satellite double back with his own eyes. He didn't conclude that engineers at NASA or in the Soviet Union must have secretly achieved a breakthrough in satellite propulsion. Instead, he believes he saw a spacecraft of extraterrestrial origin. “Critters at least as clever as us had figured out how to get around spacetime far better than we are capable of doing,” Woodward says. That changed the question, he says, from if it was possible to how.

Never one to doubt the power of the human intellect, especially his own, Woodward reckoned he could build a similar interstellar propulsion system if he put his mind to it. “If somebody figured out how the hell to do something like that, they probably aren’t an awful lot smarter than I am,” Woodward recalls thinking at the time. “So I thought maybe I should devote a little time to trying to do that.” It was a project that would occupy him for the rest of his life.

Woodward completed his master’s degree in physics at NYU in 1969, and he left to do a PhD in history at the University of Denver shortly after. His decision to pivot from physics to history was a pragmatic one. As a master’s student, he spent a lot of his time combing through old scientific journals in search of promising gravitational research that had been abandoned or hit a dead end so he could pick up the torch. “I was doing the history of science already, so I might as well get a degree in it,” Woodward says. “It was an obvious thing to do.” As an academic historian, he’d enjoy the job security that comes with uncontroversial research and still have the freedom to study fringe gravitational topics as an avocation. He accepted a position in the Cal State Fullerton history department in 1972.

It’s not like Woodward’s passion for fringe physics was a secret. In addition to a trickle of historical research, he regularly published technical papers in mainstream science journals on arcane gravitational subjects. “It is unusual that a professor of history would set up a research lab in physics, but Jim was recognized as a serious scholar and committed researcher,” says Dorothy Woolum, a physicist who arrived at Fullerton shortly after Woodward. He was particularly interested in using pulsars, a type of rapidly spinning neutron star that had only recently been discovered, to try to detect an unknown and exotic coupling between electromagnetism and gravity predicted by the Nobel Prize–winning physicist Patrick Blackett. Alas, Woodward’s work on pulsars only managed to raise skepticism among his peers. “Many people looked at me as a crank and blew me off,” Woodward says. “I wouldn’t recommend it as a career path.”

The electromagnetism stuff was bad enough, but it was Woodward’s emerging ideas about inertia that really got them riled up. Inertia is the resistance you feel whenever you push on an object. (Or, as Newton put it, inertia is why an object at rest tends to stay at rest.) Though ubiquitous and fundamental, no one has penned a full explanation of it. Woodward inherits his ideas about inertia from Einstein, who was inspired by the 19th-century physicist Ernst Mach. Mach posited that inertia is the result of the gravitational interactions of everything in the universe. In other words, the resistance from the sidewalk when someone walks on it or from a pool wall when a swimmer executes a tumble turn is partly due to starstuff billions of light years away. Einstein called this idea “Mach’s principle” and incorporated it into general relativity, his theory of gravity.

From the start, Mach’s principle was a controversial addendum to general relativity. Some of Einstein’s contemporaries, especially the Dutch mathematician Willem de Sitter, labored to show that his concept of inertia was inconsistent with other mathematical implications of general relativity. But it was the physicist Carl Brans who finally expelled the idea from respectable physics. In Brans’ PhD thesis, published in 1961, he used mathematics to demonstrate that inertia could not be explained by the gravitational influence of distant matter in the universe. After Brans’ paper, “everybody assumed that inertia à la Einstein was not contained in general relativity,” Woodward says. “That’s still the view of most general relativists.”

But as Woodward dug deeper into the history and science of general relativity, he couldn’t shake the feeling that Brans had gotten it all wrong. And as he discovered in the autumn of 1989, if you accepted Einstein’s view that inertia was inextricably linked to gravity, it opened up the possibility for propellantless propulsion.

Woodward’s views on gravity and inertia aren’t mainstream, but it’s not crazy to think Einstein might have been right all along. “I'm pretty comfortable with Jim's take on it, because it's very historically oriented,” says Daniel Kennefick, an astrophysicist and historian of science at the University of Arkansas, who has collaborated with Woodward. “He is very much motivated by Einstein's understanding of Mach’s principle. It's not at all unusual for an idea to be discovered, rejected, and then later make a comeback.”

In Einstein’s famous equation, E=mc², an object’s energy, E, is equal to its mass, m, multiplied by the speed of light squared. That means if you change an object’s energy, you will also change its mass. An object’s mass is a measure of its inertia—that’s why it takes greater force to push a more massive object than a less massive one—so changing its energy will also change its inertia. And if, per Mach’s principle, inertia and gravity are one and the same, then changing an object’s energy means messing with the very fabric of spacetime. In theory, anyway.

Woodward realized that if Einstein was right and inertia really is gravity in disguise, it should be possible to detect these brief changes in an object’s mass as its energy fluctuates. If part of an object accelerated at the exact moment when it became a little heavier, it would pull the rest of the object along with it. In other words, it would create thrust without propellant.

Woodward called these temporary changes in mass “Mach effects,” and the engine that could use them a Mach-effect thruster. By combining hundreds or thousands of these drives, they could conceivably produce enough thrust to send a spaceship to the stars in less than a human lifetime. How to keep a person alive in space for decades is still an enormous question. But it is a mere footnote to the more fundamental issue of figuring out how to cross a void trillions of miles wide in any reasonable amount of time.

BY 1995, WOODWARD’S ideas about Mach effects had coalesced into a full theory, and he turned his attention to building a thruster to prove it. The design he settled on was simple and opportunistic. A local electronics manufacturer was relocating, and an employee had alerted the university it had some leftover materials on offer. Woodward swung by its old office and snapped up a pile of piezoelectric disks the company had left behind.

To build his interstellar engine, Woodward mounted the piezoelectric disks to a block of brass and put a cap on the other end to hold it all in place. When piezoelectric disks are hit with a pulse of electricity, they bulge slightly. This expansion causes them to push off of the brass block and accelerate in the opposite direction. According to Woodward’s theory of Mach effects, the electric current would also make the piezoelectric disks ever-so-slightly heavier. This causes them to pull the brass block toward them. When the electricity stops flowing, the whole ensemble will have scooted slightly forward. By repeating this process over and over, Woodward figured, the Mach-effect thruster should accelerate. Fearn, his closest collaborator, compares it to rowing a boat on the ocean of spacetime.

Over the next few years, he managed to coax a few hundred nanonewtons of thrust out of his Mach-effect drive. Most of Woodward’s peers dismissed his nearly imperceptible results as a measurement error. It is not hard to see why—when you blow out candles on a birthday cake, you produce around three orders of magnitude more force than what Woodward was reporting. Even if the device did work, it wouldn’t be enough to move a small satellite, much less a starship.

Nevertheless, Woodward’s Mach-effect thrusters attracted the attention of researchers in government and industry. In 1997 he gave a presentation on his work at Lockheed Martin, and a few months later officials from the Department of Energy and Sandia National Laboratories paid a visit to his lab. But funding never materialized. So he pressed forward on his own, assisted by his graduate student Tom Mahood and a handful of other collaborators. Then he found out about the cancer.

In 2005, doctors found a 2-inch tumor in Woodward’s left lung. The cancer had spread to his lymphatic system, causing the left part of his face and neck to swell. His prognosis was bleak. His doctors told him his odds of surviving the year were 1 in 3; the odds that he’d live five years were 1 in 100. He enrolled in a few clinical trials to try experimental therapies and had extraordinary results. Within months, the cancerous mass in his lungs had virtually disappeared. The treatments came with complications—Woodward experienced heart failure and lost the ability to walk without a pair of canes—but he survived.

Woodward’s favorite Einstein quote is “Coincidence is God’s way of remaining anonymous,” and his cancer ordeal only reinforced his belief in its fundamental truth. “There was just one coincidence after another,” Woodward says. “By all rights, I should have been dead and gone 15 years ago.”

Reckoning with his mortality only strengthened his resolve. On the days when he wasn’t in a doctor’s office, he was in the lab trying to breathe life into his machines. Then a twist of fate led him to team up with Fearn. For 20 years Woodward had had an expansive lab in the physics department, but Cal State Fullerton now needed the space to open a new Center for Gravitational-Wave Physics and Astronomy. “If it had been anything other than gravitational physics, I probably would have resisted,” Woodward says. “But since it was gravitational physics, I was delighted to move.”

Woodward found some space in an empty back office that technically belonged to Fearn, who was on sabbatical. When Fearn returned, he discovered he was now roommates with the university’s most eccentric scientist. “I was really pissed off, because everything was a jumbled mess with these big computers stacked on top of each other, and all my books had been shoved into my room,” Fearn recalls. “And here's this strange guy in my back room doing these weird experiments.”

At first, Fearn took only a casual interest in Woodward’s experiments. But as time passed, he couldn’t help noticing his roommate’s results were improving. “That’s when I started to get interested and talk to him about what he was doing,” he says.

Soon, he was hooked. He offered to help, and the duo quickly became inseparable, a professional relationship that’s part The Odd Couple, part Watson and Crick. Although he didn’t fully buy into Woodward’s theoretical explanation for his Mach-effect thrusters, Fearn couldn’t resist the challenge. “How many people can say they’re trying to build a propulsion system to send spaceships to the stars?” Fearn says. “That’s what we’re doing here.”

THE ADVANCED PROPULSION community is a small one. Perhaps a few dozen physicists and engineers around the world are working on problems such as fusion-powered rockets and faster-than-light travel. Everybody knows everybody, and as in any small community, there’s infighting and gossip. But there’s also a deep bond that comes with having to convince the rest of the scientific establishment that you’re not thatcrazy. “People will get into shouting matches,” says Greg Meholic, an engineer at the Aerospace Corporation working on advanced propulsion. “But then, when the workday is done or there's a break, everybody's friends.”

Meholic says he first met Woodward at an advanced propulsion conference in the ’90s. “The self-skepticism he had at the time was very appealing,” says Meholic. “He didn't ever make the claim that he had therevolutionary thing and we’re going to be flying to the stars in 10 years.” After one of Woodward’s presentations, Meholic offered his engineering perspective on his thruster designs, and they’ve been friends and collaborators ever since. So in 2016, when Meholic heard that Woodward and Fearn had teamed up with the Space Studies Institute, a nonprofit founded by the physicist Gerard O’Neill, to start a conference for advanced propulsion, he knew he had to be there. “Everybody who's ever done any research at all in this kind of work was invited to come,” he says.

The workshop was held that September in Estes Park, Colorado. It was good timing. Shortly before the conference began, a research paper leaked on an online space forum that purported to show the first strong results from experiments on another approach to propellantless propulsion, called the EmDrive. Designed by a NASA research group led by physicist Sonny White, the EmDrive was supposed to produce thrust by essentially bouncing microwaves around a closed, conical cavity. It’s the closest thing Woodward’s thrusters have to a rival.

Woodward and Fearn also had exciting results to share. Their Mach-effect thruster appeared to be producing a few micronewtons of thrust, a record for the device. Even better, three other researchers who had tried out a Mach-effect thruster in their own labs confirmed they had seen it produce thrust, though not as much as Woodward and Fearn saw.

The work was enough to earn Woodward and Fearn a coveted spot in NASA’s Innovative Advanced Concepts program. In 2017 the duo secured a $125,000 grant from the space agency. It was the first funding Woodward had ever received to work on his device. Over the years, he had poured about $200,000 of his own money into building the thrusters. “Jim is a master of doing amazing things with next to nothing,” says Mahood, his former graduate student who helped him design and build many of the early devices.

As part of the NASA grant, Woodward and Fearn were tasked with both boosting the performance of their thrusters and finding a way to put them to practical use. So they collaborated with the physicist Marshall Eubanks, an expert on interstellar mission concepts, to design an uncrewed spacecraft that could reach a nearby star system.

Their design, called the SSI Lambda in homage to the Space Studies Institute, is an alien-looking craft that consists of a long triangular truss flanked by three heat radiators that protrude from its body like feathers on an arrow. An array of roughly 1,500 scaled-up MEGA drives situated around its middle provide thrust. A small modular nuclear reactor would power the thrusters.

“The SSI Lambda probe using MEGA drive thrusters is a truly propellantless-propulsion spacecraft,” the team wrote of the design in its report to NASA. “It can travel at speeds up to the speed of light in a vacuum with only consumption of electric power. No other method for travelling to the stars and braking into the target system has been put forward to date, which also has credible physics to back it up.”

In 2018, NASA awarded Woodward and Fearn a larger grant worth $500,000. But that welcome development coincided with some bad news from Germany: Martin Tajmar, a physicist at the Dresden University of Technology who had earlier replicated Woodward’s work, had tried again and this time failed to detect thrust. Woodward counters that Tajmar was missing a critical piece of equipment. Tajmar isn’t convinced. “I always had the suspicion that the thrust could be some thermal or vibration artifact,” says Tajmar. “My conclusion after many years is that it’s just vibration.”

In early 2019, Fearn flew to Germany to deliver another thruster to Tajmar. He stayed long enough to help Tajmar and his team set up the thruster and run some preliminary tests. Although these tests registered thrust, they were much smaller than what Woodward and Fearn had detected in their own lab. Tajmar visited Woodward and Fearn in California later that summer with more bad news. After Fearn had left, he’d run more tests in different configurations and again failed to detect thrust. “We tested it in his original configuration and we tested it by changing their mounting,” Tajmar says. “You can easily change your vibration artifacts by introducing some rubber or changing a screw, and that's exactly what Jim Woodward is doing now.”

But while investigating Tajmar’s results, Woodward discovered Fearn had made a miscalculation that caused the thrust to appear several times larger than it really was. He took it in stride. “Everybody makes mistakes,” says Woodward. Although it explained the discrepancy between their results and what Tajmar saw in his lab, it also made their promise to NASA—to reliably produce tens of micronewtons of thrust by the end of the grant—seem downright impossible.

They spent the next six months struggling to get their device to put out more thrust. Then last spring, Woodward realized the way they had mounted the thruster was damping the harmonized vibrations that are the key to producing thrust. So he built a new kind of mount that positions the stack of piezoelectric disks in the center of two rods riding on ball bushings.

The results were apparent immediately. The MEGA drive started regularly producing tens of micronewtons of thrust and before long it was producing more than 100 micronewtons, orders of magnitude larger than anything Woodward had ever built before. “I never thought I would see the day that I would be saying this to anyone,” Woodward says. “I figured we'd still be struggling along in the 1- to 5-micronewton range.” For the first time, the pair could see the MEGA thruster lurch forward with their own eyes. Sure, it was only scooting a half millimeter, but at least it was visible.

Seeing may be believing, but Woodward and Fearn both say they reacted to their results with more suspicion than jubilance. “I was shocked at the huge increase in measured force,” says Fearn. He initially thought that the movement might be due to the device’s balance recalibrating, but he says that doesn’t explain how the device is generating enough force to overcome the friction in the ball bearings so that it could move forward. Woodward is also suspicious, although less than Fearn. The movement is what his theory predicts, after all.

“I am confident that a real force is present, but I sometimes wonder if it isn’t accompanied by a spurious part,” says Woodward. Whence the suspicion? “Just years of tracking down false positives, I guess,” he says.

With ample new data in hand, they’re now focused on getting their device into the hands of other researchers so they can independently replicate their results. Mike McDonald, an aerospace engineer at the Naval Research Laboratory in Maryland, will be among the first to do so. He leads an internal program for independently testing advanced propulsion systems, which has previously shot down promising results from the EmDrive. Like any good experimentalist , he’s skeptical—but it’s an optimistic sort of skepticism. “I'd say there's between a 1-in-10 and 1-in-10,000,000 chance that it’s real, and probably toward the higher end of that spectrum,” says McDonald. “But imagine that one chance; that would be amazing. That's why we do high-risk, high-reward work. That’s why we do science.”

McDonald is waiting for his lab to resume normal operation next year, once the pandemic eases, to begin testing. He says the first step will involve simply replicating Woodward’s experiments and seeing if he observes the same signal. Then he’ll begin weeding out possible sources of false positives, such as vibration or the thermal expansion of components. One test will be to let the device run at its resonant vibrational frequency for minutes or hours at a time. If the signal persists, there’s a good chance it’s legit.

There’s a problem, though: No one is sure what the right vibration frequency is for the device. When Woodward and Fearn conduct their tests, they cycle through a broad spectrum of frequencies, and it’s only when they pass a resonant frequency that they detect thrust. But that resonant frequency constantly shifts as the device heats up. It also varies with the experimental setup. One of their collaborators, the engineer Chip Akins, is building a custom amplifier that will track the resonant frequency as it changes. So rather than producing a split second of thrust as Woodward and Fearn cycle through the frequencies, the MEGA drive will, in theory, be able to produce a sustained thrust.

If McDonald and other researchers are able to replicate Woodward and Fearn’s results, the next big step would be an in-space demonstration of the device. He and Fearn hope to have a flight-ready version of the thruster finished within a year. If an in-space demonstration on a small satellite around Earth goes well, more ambitious missions might await. “Do I feel vindicated? No, not really,” Woodward says. “I’ll feel vindicated if I live long enough to see someone publicly say, ‘Yes, these things really work.’”

But even if the community accepts that the thrusters work, that doesn’t mean they’ll accept Woodward’s explanation of why they work. “In my opinion there is no merit to Woodward's theory,” says Mike McCulloch, a physicist at the University of Plymouth who has advanced an alternate idea called quantised inertia that he purports can also explain some of Woodward’s results. “I think the experimental results are more interesting than the theory.” Even Fearn, Woodward’s closest collaborator, has his doubts. But he also doesn’t have any other way to explain what he and Woodward are seeing in the lab. “I haven't been able to disprove it, and believe me, I've been trying to disprove it for the last 10 years,” he says.

Woodward’s at peace with his critics. If what he’s seeing is real—if his MEGA drive really produces thrust—he is convinced that his theory is the only one that can explain it.“That’ll sort itself out eventually,” he says.

But if he was once a skeptic’s skeptic, Woodward now seems almost religious in his faith that what he’s seeing is real. Some of his supporters can’t help but wonder if it’s led him astray. “As time has gone on, Jim has gotten much more staunch in his approach,” says Meholic. “He's literally come out and said at some point that the textbooks are wrong and I'm right.”

If it all turns out to be an illusion and Woodward has spent his life chasing vibrations, his colleagues are the first to admit it wasn’t for nothing. “There is a worldwide effort looking at Jim’s devices, because this is really the only game in town at this point,” says Meholic. “It's been wonderful to have someone like him in the community that actually is doing something to advance these things, because that’s what’s really critical."

Whether you think Woodward is a lunatic or a visionary is mostly a matter of your perspective on gravity. A kiss on the cheek or a shot from a gun or a vibration in a stack of piezoelectric crystals either implicates a galaxy billions of light years away, or it doesn’t. The experimental data won’t lie, but if Woodward hasn’t discovered the interstellar engine we’ve been waiting for, he’s kept the dream alive for the next generation of would-be star surfers who might.

Quelle: WIRED