There is no evidence of intelligent aliens in other parts of the universe. They might be hanging out on Dyson spheres circling the husks of sunlike stars called white dwarfs if they exist.
Ben Zuckerman, a professor of physics and astronomy at the University of California Los Angeles, told Live Science in an email that we should be looking for extraterrestrials.
Calculating how many advanced civilizations are in the universe could be done based on what the search finds.
There may be hostile alien civilizations in the sky.
Energy is needed for food, for transport, for conflict, for comfort and for convenience. According to The World Counts, Earth's 7.8 billion people use over half a billion joules of energy each year, equivalent to the energy output of over 14 million tons of oil. The sun is the largest generator of energy in the solar system and we don't have the technology to use it.
If humans covered every square inch of Earth's surface with solar panels, it would generate more than a ton of energy. The majority of the sun's energy is lost by that.
This is the motivation behind the invention of the Dyson spheres. If an advanced civilization really wants to harness the awesome energetic output of their home star, they have to build megastructures to block out at least some of the star's light and convert that energy into other useful things. Dyson's original proposal of a solid sphere with 100% solar coverage doesn't work because of stability issues, as it would be impossible to keep the star at the center. It's easy to imagine an advanced species building rings or swarms of giant solar panel-covered structures to complete the task.
Every star has a finite lifetime, no matter how advanced a species is or how many Dyson sphere-like objects they build. Someday a civilization will arise around a star that will turn into a red giant and leave behind a white dwarf. The outer planets of the solar system will be frozen as the white dwarf cools off.
Staying on the surface of a planet is not a viable option in the long run. It's possible for aliens to either pack up and leave, find a new home, or build habitats that harvest the radiation from the white dwarf.
It seems unlikely that an alien civilization would choose to travel to a new star just to build a Dyson sphere, according to a new paper written by Zuckerman. They will only build megastructures around their home stars, which will eventually turn into white dwarfs.
Is every star a planet?
Scientists can connect stellar lifetimes with the prevalence of Dyson spheres. Zuckerman believes that if astronomer look for Dyson spheres around white dwarfs and come up empty, they can estimate how many advanced civilizations exist in the universe. Astronomers have only measured a small portion of the white dwarfs in the universe. We should see at least one Dyson sphere in our surveys if aliens decided to build Dyson spheres around their homes. The upper limit on the number of alien Dyson spheres built around white dwarfs is set if we don't see any. Zuckerman believes that the most likely outcome of advanced civilization is to build a Dyson sphere around their white dwarf, even though there could be aliens who decide not to do so.
This search is going to be difficult.
Zuckerman told Live Science that the signal from the Dyson sphere would likely be very faint compared to the star about which it orbits.
What is that sign?
There are two effects of a Dyson sphere around a white dwarf. It will block the light from reaching Earth if it is large enough or close enough to the star. Dyson spheres might be able to add a signal from the IR. The white dwarf's radiation will be absorbed by the megastructures. The process will leave behind some waste heat that will be absorbed by the light in the room.
According to the research paper, we have found many white dwarfs with excess emission, but that is due to dust in the systems.
There is no evidence of Dyson spheres in existing surveys. Zuckerman thinks that no more than 3% of planets around sun-like stars give rise to a civilization that builds a Dyson sphere around a white dwarf. There are so many planets around sun-like stars that this calculation only provides an upper limit of 9 million potential white dwarf spheres.
Zuckerman doesn't know how many advanced civilizations may live in the Milky Way.
Zuckerman thinks that technological life may be a very rare occurrence.
The original article was published on Live Science.
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