Aliens: where are you

  The “Death Star” in Star Wars may really exist in a corner of the universe. Now, astronomers have launched a number of plans to find alien artifacts of this scale or even larger scales.
  Our hope of finding an extraterrestrial intelligent life seems to be becoming increasingly elusive. Mars and Venus are no longer the vibrant places we once suspected. Although life may exist in the ice sea of ​​the outer solar system, it is almost certain that they are at best microbes. The search for radio signals sent by more distant aliens has made some astronomers very frustrated. They even suggested that we should shout “Hello” in interstellar space, hoping to encourage those aliens to make Response.
  Looking for traces of extraterrestrial
  existence of any civilized than we are likely to be much a long history, but also much more advanced. If there are aliens, then there must be footprints left by them, traces of their buildings, wastes they discarded, and so on. Perhaps, we should change our minds and not always try to intercept the communication signals of aliens, but should look for artificial signs left by aliens.
  A few days ago, three teams of astronomers are planning to scan the vast universe. The two teams hope to see the shadow of the alien industry in the twinkling stars. The third team, like the archaeologists sifting the rubble on Earth, is looking for waste left by aliens. It’s just that what they are looking for is far greater than the pottery fragments. What they are looking for can be said to be giants: power stations about the size of planets, rings or spherical shells surrounding the entire star, computers the size of the solar system, and perhaps even large enough to be assembled to darken the entire galaxy. Hardware facilities.
  It is crazy enough to find such a “behemoth”, but it is definitely not a fantasy. Human beings have already covered the vast areas of the earth’s surface with roads and cities, and our Great Wall can also be seen from space. What’s more, today’s technology can send various probes to other planets. We have done all this in just a few hundred years. What can more advanced civilizations do in tens of thousands or even millions of years?
  ”Dyson Ball” Hypothesis
  In 1960, the physicist Freeman Dyson put forward an idea called “Dyson Sphere”. He believes that civilization is always growing, human beings, and alien civilizations are also the same. If alien civilizations continue to develop and grow, they will consume more energy, and the largest energy source in any star system is the star itself. Take our earth, that star is the sun. Now, our total energy consumption rate is approximately equal to 0.01% of the total sunlight hitting the earth, so the sun can easily meet all our needs. However, if energy demand grows at a rate of 1% per year, the energy we need in 1,000 years will exceed the solar energy that hits the earth’s surface. So, for the energy we need, we need to build various solar power stations and power plants.
  When alien civilizations encounter a similar situation, they may also start to build solar power stations, power plants, and even settle in space. By mining asteroids, planets, and even the stars themselves, they slowly expand outward. Dyson’s conclusion is that after millions of years, this star may be completely enveloped by a huge artificial solar panel spherical shell.
  The scale of the “Dyson Ball” is almost unimaginable. A spherical shell with a radius equivalent to the earth’s orbit has a surface area more than 100 million times the surface area of ​​the earth. It is no easy task to build such a big guy, because to consider the issue of gravity, it is necessary to build many large power stations on disjoint orbits so that they can effectively wrap the central star. If aliens have built the “Dyson Ball”, then we have a chance to discover it.
  Such a spherical shell will block the starlight, making it invisible to our naked eyes, but this spherical shell will still emit waste heat in the form of infrared radiation. Therefore, Carl Sagan pointed out in 1966 that if an infrared telescope finds a warm celestial body but can’t see anything in the visible light band, it may be a “Dyson sphere.”
  Take an interstellar journey into the universe
  Does the “Dyson Ball” really exist? Some astronomers are constantly looking at the sky and screening data. In 1983, several astronomers used infrared astronomical satellites to conduct a 10-month sky survey, screening various data, but gained little; in 1985, Vyacheslav Slash of the Russian Institute of Space Research conducted the first An attempt to find the “Dyson Ball”; in 2009, Richard Carrigan of Fermi National Laboratory released the latest search results. Carrigan did not find a convincing sign of the existence of the “Dyson Ball”, but his search scope was really limited. He only searched around the sun-like stars within 1,000 light years of the earth. This is only a very small part of the Milky Way, which is 100,000 light-years in diameter.
  Few people join Carrigan and others to search for alien artifacts. One reason is that it is difficult to obtain funding for such projects. In 2012, the Templeton Foundation, which was established by a billionaire to fund research on “big problems”, solicited proposals for its “new frontline” projects, especially those that are extremely exploratory but not practical. Projects that are not normally funded. Several astronomers seized this opportunity to look for signs of aliens. In October 2012, the “New Frontier” project approved 3 independent search plans.
  A team led by Jason Wright of Pennsylvania State University in the United States will reanalyze the data obtained by the two space infrared observatories to find the waste heat emitted by the “Dyson Ball”. The two infrared observatories are: the Spitzer Space Telescope launched in 2003, and the large-field infrared survey probe launched in 2009. Povich is also a member of the team, he focuses on searching in the galaxy. Povic’s search range is now a thousand times larger than that of Carrigan.
  Wright guessed: “Interstellar travel should be no more difficult than building a’Dyson Sphere’. An alien civilization with such a high level of technology will expand outward in a few million years, colonizing the entire galaxy, It’s very difficult for an interstellar civilization to die, because there are too many survival ships. If such a thing really happened in the galaxy, then the Dyson sphere should be everywhere.”
  Therefore, Wright is planning to enter a deeper universe and start an adventure. “So we are looking for large and bright galaxies without optical counterparts.” Wright said. If some civilizations have already conquered a galaxy as large as the Milky Way, this project will be able to discover their super project 1 billion light years away. If they have colonized the entire galaxy cluster, they can be detected by us at a greater distance.
  Although the scope of action is extremely wide, the method of detecting waste heat has its own limitations. If the alien only builds a thin ring composed of collectors, or the Dyson sphere is built with many gaps to allow a large amount of starlight to pass through, this method will not detect anything. However, this is where the other two detection projects come in. With the help of the Kepler Space Telescope, which searches for alien planets, they will search for relatively small-scale alien civilization artifacts. The Kepler telescope monitors approximately 150,000 stars at close range, looking for the faint brightness changes caused by planets passing in front of the stars. Thousands of new candidates for alien planets have been discovered.
  Broaden their horizons and look for anomalies “candidate”
  Another group of Princeton University, USA Luciano Arnie Wall Kewei Zi leadership, but also Kepler telescope data to find anomalies. Volkowitz believes that the “Dyson Ball” speculation and the speculation of some other man-made objects are all in vain. “People spend a lot of time trying to psychoanalyze aliens, but we don’t know what their technology looks like. The more you try to imagine what the aliens will do, the more you will limit your horizons. “This is why her team does not set any premises and focuses on finding anything strange. Volkowitz believes that they should be able to find interesting candidates within a few months.
  Those candidates are not necessarily “big guys”, they can be anything that can change the starlight. For example, a giant reflector used to generate electricity or drive a solar sail spacecraft will produce a distinctive flash. In addition, if aliens have the ability to modify the physical state of stars, such as extending the life of their sun or producing useful elements, then these man-made changes in the stars themselves will also appear.
  Volkowitz said: “We know what planet transits, stellar sunspots and flares look like, so we are looking for changes in starlight that known astrophysics can’t explain.” Of course, just discovering something novel, It does not mean that the aliens must be there. All the scientists involved in the research are also happy to discover new natural phenomena. For some people, this is the value of this search.
  As the honorary consultant of the “new early stage” project, Dyson himself is satisfied with all this. “The search for alien man-made objects should not be separated from the normal exploration of the universe,” Dyson said. “We explore a dazzling array of natural celestial bodies. If something weird enough comes out, it is possible. It’s artificial.”