The world's most powerful laser attempts to unravel the secrets of the universe

They are the strongest lasers in history, and their beams are helping scientists explore the structure of the universe.
In a research laboratory at the University of Michigan, bright green light fills the vacuum chamber of a technology giant. It is the size of two tennis courts. The walls are shielded with 60 centimeters of concrete to prevent radiation leakage, and workers wear masks and hairnets to ensure that precision electronic equipment is not affected.

This is Zeus, the most powerful laser in America - this month, it roars past.

Unlike continuous lasers that scan barcodes in stores, Zeus is a pulsed laser that continuously emits at a frequency of one-fifth of a second. Each beam of light can reach a peak power of 3 beats per watt - equivalent to a thousand times the world's electricity consumption. For example, a laser that can generate such extreme compressed energy will help researchers study the quantum laws that support reality, or reconstruct the conditions of extreme astrophysics in space.

But Zeus is not the only giant laser that may reveal new discoveries in the coming years - many other high-power lasers in facilities from Europe to Asia are also following suit. "The entire field is indeed growing," said Karl Krushelnick, director of the G é rard Mourou Center for Ultra Fast Optical Science at the University of Michigan. People are pushing for this technology and looking for interesting science.

In the UK, a laser called Vulcan 20-20 will become the world's most powerful laser after completion in 2029. It will produce a beam of light that is one million, one billion, and one billion times brighter than the strongest sunlight. The energy generated by this single pulse is more than six times that generated worldwide, but its duration is less than one trillionth of a second, and its target size is only a few micrometers. Like Zeus, the Fire God 20-20 will invite scientists from around the world to conduct experiments that may rewrite our understanding of the universe, nuclear fusion, and even create new materials.

The 20 watt Vulcan 20-20 is an upgrade of £ 85 million to the existing Vulcan at the Havel Central Laser Facility in Oxfordshire - the facility is currently being demolished. At present, its one meter wide mirror is equivalent to two Olympic sized swimming pools, each weighing 1.5 tons. Thick and thin white lines wind out from the laser hole as the equipment bends around the room. In 1997, when Rutherford Appleton Laboratory was first built, it was considered the most advanced, with the new laser increasing brightness by 100 times.

"What is impressive is not just the power, but the intensity of the laser," said Rob Clarke, head of the CLF Experimental Science Group. To understand this intensity, imagine 500 million standard 40W light bulbs. Now "compressing light into something about one tenth the size of human hair," he said. The result is a very, very strong light source, which creates all the interesting plasmas, such as huge electric and magnetic fields, and particle acceleration.

Vulcan 20-20 will allow scientists to conduct astrophysical research in the laboratory - reconstructing the conditions of distant galaxies to analyze the internal workings of stars or gas clouds, or the behavior of matter when exposed to specific temperatures and densities. "This research field is driven by the desire to study the universe," explained Alex Robinson, chief theoretical plasma physicist at CLF. He said that astrophysical research is usually "observational". If you aim at it with a certain telescope, you will see various things. But this raises the question of what exactly happened. It is hoped that conducting experiments with this power of laser will allow for the first truly rigorous testing of the validity of certain theories.

One of the mysteries they hope to investigate at the University of Oxford is the origin of magnetic fields, which surround most substantial objects in the universe, such as stars and planets. "Why are these magnetic fields present? This is not entirely obvious," Robinson said. "There is no observation that can truly trace and test the reasons for their initial appearance. One testing method may involve merging matter to generate shock waves and adding artificial turbulence, such as turbulence caused by molecular clouds, planets, and dust, to see if a" magnetic field could be generated ".".

Other experiments will explore the origin of cosmic rays, how jets are formed, and the internal structure of giant planets.
Researchers will also use Vulcan 20-20 lasers to study the formation of new materials. Boron nitride is a harder material than diamond and may be found to be metastable - produced under very high pressure and strength conditions manufactured in the laboratory, and then able to survive at ambient temperatures. "So the question is, what other materials can you create in the same way?" Robinson said. Will they have excellent electronic or optical properties? I don't know. But at least one gold nugget tells us that there is something worth exploring.

Realize integration
Nuclear fusion is also on the hot list of ultra-high power lasers. In July of this year, researchers at the Lawrence Livermore National Laboratory National Ignition Facility in California achieved a net increase in energy for the second time using lasers. After the initial breakthrough made by the center in December last year, this year's experiment has created higher energy production than the first time, once again sparking hope that clean energy may replace our existing energy.

Fusion is also located in M, Romania ă One of the key research areas of Gurel's Nuclear Physics Aurora Infrastructure Center, with a strength of 10 petawatts, retains the title of the world's most powerful laser.

In the past year, operators of Romanian lasers have started collaborating with private companies to develop technology and provide power for the world's first commercial fusion factories. Using the "chirped pulse amplification" technique, which won the 2018 Nobel Prize in Physics for Mourou and Donna Strickland, the laser pulse will be stretched, its peak power reduced, and then amplified and compressed again. Clark said that this "almost completely changed the face of laser development", allowing for higher intensity to be achieved at low power.

Their research on the physical processes of this interaction is expected to be published within three years, followed by the construction of the first batch of commercial fusion power plants in the 2030's.

The bigger the better?
Physicists are keen to emphasize the collaborative nature of this field, but scale is still a boast. According to Chang Hee Nam, director of the Korean Center for Relativity Laser Science and professor at Gwangju University of Science and Technology, their laser currently "maintains the highest intensity laser record in the world", reaching 10 ^ 23 W/square centimeter - or, in other words, as strong as all light focused on just over a micrometer on Earth. Or less than one-fifty of the diameter of human hair.

Korean scientists are using this technology to explore proton therapy, a cancer treatment method that targets patients with tumors with a positively charged beam of light.

On CoReLS's four beat tile machine, research that can generate new medical applications and test century old ideas about the state of the universe has been well explored, but the team has not stopped there. Nam said, "We are currently pushing for higher Petawatt lasers; we are preparing some suggestions for a 25 Petawatt laser beam. If it is put into use within the next six years as he hopes, it will put the yet to be built Vulcan 20-20 in comparison.".

However, Vulcan's Clarke said that strength and intensity are not everything. The most important indicator now is "What can you do with it? What science are you driving? What do you plan to get from it?" He said, "These lasers and the researchers who study them are the most concerned." The key is to build it correctly and use it correctly. "

Source: Laser Net