How to dominate the universe in three easy steps … 
 
 Step 1: Harvest all of your planet's resources. 
 
 Step 2: Harvest all of your nearest star's energy. 
 
 Step 3: Harvest all the energy from all the stars in your local galaxy; then move on to another galaxy. 
 
 Congratulations! Your species now has all the elbow room it needs to grow into a universal superpower. 
 
 That's one Russian astronomer's perspective, anyway. Astrophysicist Nikolai Kardashev first proposed these three phases (called Level I, II and III) of galactic expansion — which he referred to as the three "types" of technologically advanced civilizations — in 1962 as a way to measure the energy consumption of increasingly powerful societies. Recently, a paper posted June 13 to the preprint journal arXiv.org has revived Kardashev's model and added a new, apocalyptic twist. [13 Ways to Hunt Intelligent Aliens] 
 
 According to the author of the paper, Dan Hooper — a senior scientist at the Fermi National Accelerator Laboratory in Illinois and a professor of astronomy and astrophysics at the University of Chicago — harvesting energy from distant stars isn't just the best way to increase a civilization's available resources. It's also the only way to prevent the ever-expanding universe from leaving that civilization totally alone in the vastness of space. (This study has yet to be peer-reviewed.) 
 
 "The presence of dark energy in our universe is causing space to expand at an accelerating rate," Hooper wrote in the new paper. Over the next approximately 100 billion years, the stars beyond our Local Group, or a group of gravitationally bound galaxies that includes the Milky Way, will fall beyond the cosmic horizon, meaning an observer here could never retrieve information from them over the course of the age of the universe. 
 
 At that point, "the stars become not only unobservable, but entirely inaccessible, thus limiting how much energy could one day be extracted from them," Hooper wrote in the paper. 
 
 In other words, if humans hope to meet aliens in distant galaxies, it'll be a race against dark energy, that mysterious force thought to be uncontrollably stretching our universe farther and farther apart. 
 
 That, of course, is how we'll find the aliens. 
 
 Any advanced civilization worth their starships would understand the grim reality of universal expansion, Hooper wrote, and they wouldn't just sit around idly while the universe literally passed them by. Rather, they would capture stars from other galaxies, reel them in and harvest their energy first, before those stars (and their energy) became inaccessible forever. [12 Possible Reasons We Haven't Found Aliens] 
 
 "Given the inevitability of the encroaching horizon, any sufficiently advanced civilization that is determined to maximize its ability to utilize energy will expand throughout the universe, attempting to secure as many stars as possible before they become permanently inaccessible," Hooper wrote. 
 
 So, how do you lasso a star in the first place? Scientists and science-fiction authors alike have pondered this question for decades, and their favored answer is this: Throw a giant net around it, of course. 
 
 This net wouldn't be made of twine or even metal, but of satellites — a swarm of millions of solar-powered satellites known as "Dyson spheres." Such a colossal cloud of harvesters could permanently hover around a star, beaming energy back to a nearby planet — or, as Hooper proposed in his new paper, actually use that star's energy to accelerate the whole ball of fire back toward the planet that wanted to use it. 
 
 This may seem like a tall order for humans, who are still bumbling around Level I of Kardashev's scale. (Carl Sagan placed us at about a 0.7 in 1973). But some scientists think there could be alien civilizations thousands, or even millions, of years older than ours who are already well into their Level III, star-harvesting phase. 
 
 And if another civilization has indeed begun rearranging the stars, it may not be long before Earthlings notice them, Hooper wrote. 
 
 "Those stars that are currently en route to the central civilization could be visible as a result of the propulsion that they are currently undergoing," Hooper wrote. "Such acceleration would necessarily require large amounts of energy and likely produce significant fluxes of electromagnetic radiation." 
 
 Beyond watching for those stars being dragged unceremoniously across distant galaxies, astronomers could also keep an eye out for the unusual galaxies that have had their prime stars ripped away from them, Hooper wrote. 
 
 These hypothetical, star-harvesting aliens will probably be picky, Hooper noted: Teeny-tiny stars, hundreds of times smaller than Earth's sun, wouldn't produce enough radiation to be useful; significantly larger stars, on the other hand, would likely be too close to going supernova to be used as a viable battery. Only stars with a mass about 20 to 100 times the mass of our sun would be viable candidates for capturing and hauling back to the home galaxy, Hooper said. And because solar objects in that mass range radiate certain wavelengths of light more than others, alien star harvesting would show up in the light signatures from these galaxies. 
 
 "The spectrum of starlight from a galaxy that has had its useful stars harvested by an advanced civilization would be dominated by massive stars and thus peak at longer wavelengths than otherwise would have been the case," Hooper said. 
 
 Humans likely don't have precise enough instruments yet to detect these unusual light signatures beaming from the depths of the universe, Hooper wrote. Hopefully, astronomers will develop them before our sun becomes another flaming marble in some distant civilization's collection. 
 
 Originally published on Live Science. ||||| Ancient extraterrestrial civilizations, millions of years older than humanity, would need enormous amounts of energy. By creating a swarm of satellites in a spherical shell, they could harness much of the power of their star. 
 
 Science fiction author Olaf Stapledon described spherical, energy-trapping alien structures in his 1937 novel "Star Maker": 
 
 "Not only was every solar system now surrounded by a gauze of light traps, which focused the escaping solar energy for intelligent use, so that the whole galaxy was dimmed, but many stars that were not suited to be suns were disintegrated, and rifled of their prodigious stores of sub-atomic energy." 
 
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 Recalling Stapledon's description, physicist Freeman Dysonproposed similar structures in a scientific paper in 1960. Dyson realized that alien civilizations could be recognized by their waste heat, which would be detectable as infrared radiation. Dyson proposed that really advanced civilizations would re-engineer their solar systems, perhaps dismantling planets to form a shellof satellites around their star to capture its energy. [13 Ways to Hunt Intelligent Aliens] 
 
 Astrophysicist Nikolai Kardashev proposed in 1962 that very old and advanced civilizations would be of three types: 
 
 A Type I civilization harnesses all the resources of a planet. Carl Saganestimated that Earth rates about 0.7 on the scale. 
 
 A Type II civilization harnesses all the radiation of a star. Humans might reach Type II in a few thousand years. 
 
 A Type III civilization harnesses all the resources of a galaxy. Humans might reach Type III in a few hundred thousand to a million years. 
 
 A solid shell around a star would be gravitationally unstable, and would probably require more material than all of the planets of a solar system could provide. Instead, practical Dyson sphereswould be made from millions of individual solar-collecting satellites. 
 
 Solar sails could remain in place by balancing against the pressure of light from the sun. The satellite would not be in orbit, it would actually hover in space. Such a satellite is called a "statite." Rings of statites would form a cloud around the star, collecting its energy and beaming it back to the home planet. 
 
 Dyson spheres and other mega-structures appear frequently in science fiction. In his 1970 novel "Ringworld," Larry Niven features a ring-shaped artificial structure girdling an alien star. In the 1992 “Star Trek: The Next Generation” episode "Relics," the starship Enterpriseencounters a Dyson sphere in the form of a rigid shell surrounding a star. 
 
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 Follow us @Spacedotcom, Facebook or Google+. ||||| After searching 100,000 galaxies for signs of highly advanced extraterrestrial life, a team of scientists using observations from NASA's WISE orbiting observatory has found no evidence of advanced civilizations in them. "The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization's technologies would be detectable in mid-infrared wavelengths -- exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes," said Jason T. Wright, an assistant professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University, who conceived of and initiated the research. 
 
 The research team's first paper about its Glimpsing Heat from Alien Technologies Survey (G-HAT), will be published in the Astrophysical Journal Supplement Series on April 15, 2015. Also among the team's discoveries are some mysterious new phenomena in our own Milky Way galaxy. 
 
 "Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy's stars to power computers, space flight, communication, or something we can't yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths," Wright said. "This same basic physics causes your computer to radiate heat while it is turned on." 
 
 Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space. 
 
 Roger Griffith, a postbaccalaureate researcher at Penn State and the lead author of the paper, scoured almost the entire catalog of the WISE satellite's detections -- nearly 100 million entries -- for objects consistent with galaxies emitting too much mid-infrared radiation. He then individually examined and categorized around 100,000 of the most promising galaxy images. Wright reports, "We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization." 
 
 In any case, Wright said, the team's non-detection of any obvious alien-filled galaxies is an interesting and new scientific result. "Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes. That's interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist. Either they don't exist, or they don't yet use enough energy for us to recognize them," Wright said. 
 
 "This research is a significant expansion of earlier work in this area," said Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Center in Pittsburgh and a member of the G-HAT team. "The only previous study of civilizations in other galaxies looked at only 100 or so galaxies, and wasn't looking for the heat they emit. This is new ground." 
 
 Matthew Povich, an assistant professor of astronomy at Cal Poly Pomona, and a co-investigator on the project, said "Once we had identified the best candidates for alien-filled galaxies, we had to determine whether they were new discoveries that needed follow-up study, or well-known objects that had a lot of mid-infrared emission for some natural reason." Jessica Maldonado, a Cal Poly Pomona undergraduate, searched the astronomical literature for the best of the objects detected as part of the study to see which were well known and which were new to science. "Ms. Maldonado discovered that about a half dozen of the objects are both unstudied and really interesting looking," Povich said. 
 
 "When you're looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it's not what you were looking for," said Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State's Center for Exoplanets and Habitable Worlds and a co-investigator on the research team. "Sure enough, Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what's going on." 
 
 Among the discoveries within our own Milky Way galaxy are a bright nebula around the nearby star 48 Librae, and a cluster of objects easily detected by WISE in a patch of sky that appears totally black when viewed with telescopes that detect only visible light. "This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study," Povich said. 
 
 "As we look more carefully at the light from these galaxies," said Wright, "we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning." 
 
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 The G-HAT survey was supported by a New Frontiers in Astronomy and Cosmology grant, funded by the John Templeton Foundation. 
 
 CONTACTS 
 
 Jason Wright: jtw13@psu.edu, (+1) 814-863-8470 
 
 Barbara Kennedy (PIO): science@psu.edu, (+1) 814-863-4682 
 
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– Watch out for stars moving across galaxies or losing power—it could be aliens gathering energy before the lights go out. Dan Hooper, an astronomy and astrophysics professor at the University of Chicago, posted a paper in the preprint journal arXiv.org arguing that aliens in far-off galaxies may be sucking energy from stars to offset risks posed by an expanding universe, LiveScience reports. "The presence of dark energy in our universe is causing space to expand at an accelerating rate," writes Hooper. "As a result, over the next approximately 100 billion years, all stars residing beyond the Local Group [of galaxies including the Milky Way] will fall beyond the cosmic horizon and become not only unobservable, but entirely inaccessible, thus limiting how much energy could one day be extracted from them." Therefore, he argues, an advanced civilization may use something like "Dyson spheres"—an imagined solar-powered satellite dating back to 1930s science-fiction, notes LiveScience—to harvest a star's energy or use that energy to move it closer to home. Hooper hinges his case on the work of Russian astronomer Nikolai Kardashev, who argued in 1962 that technologically advanced civilizations would expand via three steps: harvesting resources of their planet, then the nearest star, then all stars in the galaxy and nearby galaxies. So how to spot energy-grabbing aliens? Massive stars emanate certain light wavelengths, which will appear in galaxies' light signatures if stars are drained energy—that is, when humans have powerful enough instruments to detect it.