How to find alien Dyson spheres

How to find alien Dyson spheres

In our search for alien life forms, we scan the planets and eventually exoplanets for primitive biosignatures. We wait and hope for Erin's artificial signals to happen by the earth. But this may not be the best way. Any energy-hungry civilization is more advanced than our own. May leave an indisputable Technological mark on the galaxy. And yes we're actively searching for those two. Time to update you on the hunt empires. Humidity is an energy-hungry species and that hunger grows exponentially. Fortunately, we have a near and exhaustible power source raining down from above. We could satisfy humanity's current energy needs by covering a tiny fraction of a surface with sour cells. And we should probably do that by the way. But we can also expand that area indefinitely. Not by covering the entire earth but by building solar. That's a lot of room to expand if we were to cover the entire spear surrounding the sun with the radius of us or but we'd collect all of the sun's light. A 1 billion times more than we get just by covering the planet in solar cells. The idea of wrapping the sun in solar collectors is not new. Hey, British author Olive Stapleton in his 1937 story Starmaker has his own name attached to the idea. Without success. In 1960 Freeman died With inspired by Stapleton's fiction to propose that a high civilization might expand to occupy an entire sphere surrounding its home star for the purpose of both habitation and energy collection the notion became called Naturally we've talked about the plausibility of Dyson Spears in the past long story short but Freeman Dyson's original paper was not about how to build one of these things rather about how to find them if the dice spear or swarm or whatever is a natural stage in the progression of many civilizations might these be the best way to look for the science of intelligent life. Well, let's find out what our search has told us. The Earth biosphere is already A pretty good planet-scale for the collector. If you were to observe the earth from a distant solar system. You might notice it looks strangely dark. It doesn't reflect nearly as much of the sun's light as you'd expect for global water in the rock. This is thought that energy is being sucked up. But if you shift your Gaze from visible light to infrared you'd find all of the missing energy. See the sun produces a thermal spectrum. Light generated by its 6000 Kelvin surfers is distributed at all wavelengths. But it peaks in the visible part of the spectrum. And earth spice fears mostly its forest. Fraction of that light and use it to power biological processes. And in the process, they warm up shedding all of that energy as a new simple spectrum. Now at 300 or so Kelvin to spot this petrol shift from another star. You'd have to Have an incredibly sensitive telescope to pick via St. Glow from the sun's overwhelming brightness. But if a civilization has expanded to reprocess a significant fraction of its home star's light then not only could we detect that shift without the current telescope. It would be difficult to And that was also true back in 1960 when Dyson proposed that we look for these things. So how do you go about searching for a Dyson sphere? Dyson's original notion was to simply search for points of light with temperatures of a few 100 Kelvin but emitting the power of an entire area. Anything capable of producing that much power at that lower temperature must be huge. The size of the planetary orbit. In a 1966 paper Carl Sagan and ruffle, walker added some details to the calculations. Figuring out how close a Dyson sphere would need to be In order to be detected with the technology of the time. Short story or have to have been pretty close. But our infrared telescopes advanced quickly. And crucially they found their way into space. Surveys started to find many objects that fit the description. And there are some obvious natural explanations for planetary orbit size objects at a few 100 Kelvin temperatures. For example, we have protostars. The clouds of gas are in the process of collapsing into a new star surrounding a newborn star. That will eventually form a planetary system It turns out that is near impossible to identify a full dive and spear from its thermal emission alone. Take it and walk and suggest that we can sit at these infrared sources as candidate dicing steers to be followed up by scanning for narrowband radio or mission a much more telling signature Of technology. Yeah. We could go flicking through the frequency channels of gas clouds looking for alien TV. All we could think about was this event more. Dyson and Sagan's etcetera is calculations worth a full dicing sphere. One that reprocesses all of their star's light. But many civilizations find it totally adequate. To only partially harsh their stars are white. Partial bison spears could take the form of equatorial rings of collectors or swarms that don't feel the entire sparkle surface. A really any so-called megastructure that intercepts a decent fraction of their stars white. It turns out that a park She'll buy some sphere might be even more detectable than a full one-two understand how to spot such a thing let's learn a thing or two about stars. Stars are surprisingly simple beasts. For the most part, ruled by the laws of physics that we've understood for centuries. A start in its prime of life. In which the outward flow of fusion-generated energy balances the inward pressure of its own gravity its temperature is brightness. It's lifespan and so on. If a side deviates from the tight relationships between these properties then We quickly know that something is up. For example, it might be surrounded by a Dyson spear. Let's think a bit about what that would look like. It would be an unnatural combination of a large hot object, the central star, and a gigantic cool object, the partial sphere. Each would produce its own thermal spectrum at different temperatures. But from our great distance, the light from the star and the sphere would be blended into a .2 pure thermal spectrum and would be stitched together and make one weird spectrum with two little light at visible wavelength and too much at Infrared waving. If we carefully broke up the star's light with a spectrograph spanning a huge wavelength range we might be able to see two distinct thermal spectra. But that's a lot of work even for a single star. And we probably need to search for a huge number of stars. Hope we even find a single dice and steer. Fortunately, even a crude observation of a star's color and brightness can tell us that something is up. In astronomy, color refers to the ratio of brightness at two different wavelengths. For something with the purest Thermal spectrum. We can exactly identify its temperature by saying the ratio of red light to blue light. I mentioned that most stars show a tight relationship between certain properties. For example, the higher the surface temperature of the star, the higher its total power output. Or it's luminosity. If we graph temperature Against luminosity we get something called hers from Russell or HR diagram. For the temperature, we can just use color because that's easier to measure. All-stars that are in the primes of their lives. Those powered by fusing hydrogen into helium in their cause. Lie on this tight band called the main sequence that tracks Relationship between temperature and luminosity. Stars drift off the main sequence when they expand into giants at the end of their lives. Or presumably when they're surrounded by giant alien Astro engineering projects would actually do to a star on the outside Diagram. At visible wavelengths, a star's color might not change much. It'll just look dimmer. So we start to faint from its apparent temperature. Dropping below the main sequence using an infrared wavelength. Along with our visible light. We'd find too much of that. The star would look cooler, a lower temperature than suggested by Invisible color alone. Japanese astronomers who've been searching for dice and spheres for years. Calculate that a partial sphere that intercepts only 1% of the light of its star. Could shift the visible to infrared car By a sector of more than two. Over the decades, several teams successfully used more than instruments to look for stars that were both too dim and too infrared. Time and again they came up short. But the search has expanded massively. One of the latest efforts led by Swedish astronomer Eric Zackerson looked at over 200 thousand of the stars in the gigantic survey conducted by the guy satellite the team started by looking for stars that were a little too fat for their visible light color. Below is the main sequence. They found a couple of promising candidates. Then they Whether these stars had an excess of light in the infrared. And they did not do enough at any rate. Apparently, there is some non-Dyson sphere-related weirdness going on. Which may be interesting. But still, there aren't aliens. Another approach to finding partial bison spears is to Look at the strange variations in brightness and color over time as may be expected if a giant orbiting structure partially eclipses the star in any regular way and that's exactly what happened with the themed tabby star. This weird star discovered by Tabatha Boyagian exhibited complex dips in brightness Causing rumors of alien megastructures to abound. But in 2019 it became somewhat clear that its dimming was probably due to the debris that tidally disrupted moon size bodies. Yep. Still no Dyson Spears. At this point, our surveys have found no evidence for staff banning mega strikes, And new surveys that are being planned within a decade or so will either discover one or rule out anything interesting in the local part of the Milky Way. But that doesn't mean that Dyson spears aren't out there. It would be incredibly difficult to detect such an object around a low mass star. If it's on the other side of the Galaxy. What we do know is that these structures are not very common through the milky way. But that may not be true of other galaxies. There are hundreds of billions of galaxies in the observable universe. Universe. Unfortunately, we can't identify a single dicing sphere. Around individual stars. At Distant galaxies. But what if civilization in one of those has occupied this entire home galaxy and built a huge number of Dyson spares or any similar energy-hungry megastructure? With this possibility in mind, a team led by Penn State Astronomy Jason Wright used the wine Survey to look for galaxies that had too much-infrared light compared to their visible light. Nah. This is a bit tougher because galaxies aren't as simple as stars. There can be a huge variation in the amount of iR that are galaxy producers. But accounting for this. The team found no evidence for galaxy spam. Analyzed. No very energy-hungry ones at any rate. The search for galactic empires is expanding. In the past couple of years, researchers have been thinking about Dyson Spears built around the supermassive black claws in the centers of galaxies. Due to a partial bison spear. These are all long shots and honestly might seem a bit hopelessly science-fictiony. He's a very serious scientist. Starting with Breman, Dyson and Carl Sagan take the question very seriously. Good reason too the discovery that a single alien megastructure of any sort would massively change the way we think about our place in the universe. It would also point to a possible future for humanity. Something we might want to do when we grow up. It would show us that we might even have a future One that could lead our own engineering mark on the galaxy, perhaps to be noticed by younger species when they emerge in distant future parts of Spacetime. Thanks for reading.