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Astronomie - If Aliens Are Flashing Laser Beams at Us, We Now Have a Way to Detect Them

3.08.2019

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Are aliens using super powerful flashlights to get our attention? Astronomers think there's a chance they are.

Since the invention of the radio, humans have been silently listening to the stars, wondering if we are alone in the universe. But if intelligent alien life does exist, the extraterrestrials could be using other forms of technology to communicate. Astronomers are beginning to not only listen to the cosmos but also gaze toward it for other signs of alien tech: laser beams.

Breakthrough Listen, the most extensive Search for Extraterrestrial Intelligence (SETI) program in history, announced that its team will begin looking for new signs of alien technology using the Very Energetic Radiation Imaging Telescope Array System (VERITAS) at the Fred Lawrence Whipple Observatory in Amado, Arizona. 

"When it comes to intelligent life beyond Earth, we don't know where it exists or how it communicates," Yuri Milner, billionaire particle physicist and founder of Breakthrough Listen, said in a statement. "So our philosophy is to look in as many places, and in as many ways, as we can. VERITAS expands our range of observation even further."

Using VERITAS, astronomers will begin scanning the night sky for nanosecond flashes of light from nearby stars. Like a lighthouse beacon for the cosmos, these brief pulses of optical light would outshine any nearby stars and could indicate a method of alien communication.

"With the addition of VERITAS, we're sensitive to an important new class of signals: fast optical pulses," Andrew Siemion, the director of Berkeley's SETI Research Center, said in the statement. "Optical communication has already been used by NASA to transmit high-definition images to Earth from the moon, so there's a reason to believe that an advanced civilization might use a scaled-up version of this technology for interstellar communication."

VERITAS has looked for such laser pulses from the mysteriously dimming Tabby's Star after some had speculated there could be an alien megastructure surrounding it that caused the odd dimming. If the most powerful lasers on Earth were used at Tabby's Star and pointed in our direction, VERITAS could detect them. Of the 1 million stars on the Breakthrough Listen target list, most of them are 10 to 100 times closer to Earth than Tabby's Star, meaning even weaker laser flashes from intelligent aliens could be detected.

 

The array of four 12-meter optical telescopes is traditionally used to detect gamma rays — high-energy radiation emitted by extreme cosmic objects like exploding stars and even black holes — in the night sky. When gamma rays hit Earth's atmosphere, they produce very faint blue flashes of light called Cherenkov radiation, because the particles travel faster than the speed of light through air. So the blue flashes are the light equivalent of a sonic boom. The telescope array's ability to detect and pinpoint the source of these short-lived blue flashes made it the perfect candidate to search for laser beams from distant stars and galaxies.

"It is impressive how well-suited the VERITAS telescopes are for this project, since they were built only with the purpose of studying very-high-energy gamma rays in mind," David Williams, a member of the VERITAS collaboration and professor of physics at the University of California, Santa Cruz, said in the statement.

The Breakthrough Listen initiative is a $100 million, 10-year project funded by Yuri Milner, a Russian billionaire and science philanthropist. The project, which began in 2015, has already surveyed more than 1,000 stars within 160 light-years away from Earth for signs of alien radio signals, with no positive results.

"We believe that life arose spontaneously on Earth, so in an infinite universe, there must be other occurrences of life," famed physicist Stephen Hawking said during the initiative's launch. "Somewhere in the cosmos, perhaps intelligent life might be watching these lights of ours, aware of what they mean. Or do our lights wander a lifeless cosmos, unseen beacons announcing that, here on one rock, the universe discovered its existence? Either way, there is no better question."

Quelle: SC

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