lasers

Why the world’s most powerful lasers could unlock secrets of the cosmos

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Laser engineer Lauren Weinberg works on the Zeus laser system (Credit: Marcin Szczepanski/Michigan Engineering)

They are the most intense lasers ever built, and their beams are helping scientists probe the fabric of the Universe.

Inside a research lab at the University of Michigan, bright green light fills the vacuum chamber of a technological behemoth. It is the size of two tennis courts. The walls are shielded with 60cm (24in) of concrete to stop radiation leakage, and the staff wear masks and hairnets to ensure the delicate electronics are not affected.

This is Zeus, soon to be the most powerful laser in the US – and now it is whirring into life for its first official experiments.

Unlike the continuous lasers that scan your barcodes in shops, Zeus is a pulsed laser, firing in bursts a few quintillionths of a second long. Each pulse will be capable of reaching a peak power of three petawatts – equivalent to a thousand times the electricity consumption of the whole world. A laser capable of such extremely compressed energy will help researchers to study the quantum laws underpinning reality, for example, or recreate the conditions of extreme astrophysics out there in space.

But Zeus is not the only enormous laser that could reveal new discoveries in the coming years – a host of other high-powered lasers at facilities from Europe to Asia are hot on its heels. The field as a whole “is really growing”, says Karl Krushelnick, director of the Gérard Mourou Center for ultrafast optical science at the University of Michigan. “People are pushing the technology, and looking for interesting science.”The Zeus laser, which fired up this month, could help probe the nature of the Universe (Credit: Marcin Szczepanski/Michigan Engineering)

The Zeus laser, which fired up this month, could help probe the nature of the Universe

In the UK, a laser called Vulcan 20-20 will become the most powerful in the world when it is finished in 2029. It will produce a beam one million, billion, billion times brighter than the most intense sunlight. This single pulse will produce more than six times as much energy as is produced in the entire world – but will last for less than a trillionth of a second, with its target measuring just a few micrometres (or 0.001 of a millimetre). Like Zeus, Vulcan 20-20 will invite scientists from around the world to undertake experiments that may rewrite our understanding of the cosmos, nuclear fusion, and even create new matter.

The 20-petawatt Vulcan 20-20 is an £85m ($106m/€98m) upgrade on the existing Vulcan at the Central Laser Facility (CLF) in Harwell, Oxfordshire – which is being dismantled. Currently the size of two Olympic-sized swimming pools, its metre-wide mirrors weigh 1.5 tonnes (3,300lbs) apiece. Thick white wires snake out of the laser aperture, as the apparatus bends around the room. Considered state of the art when it was first built at the Rutherford Appleton Laboratory in 1997, the new laser will be 100 times brighter. 

The “impressive thing isn’t just the power, though, but rather the intensity of the laser”, says Rob Clarke, experimental science group leader at the CLF. To understand that intensity, imagine 500 million million standard 40W lightbulbs. Now “compress that light into something around a tenth of the size of a human hair”, he says. “The result of that is a very, very intense source of light, and it is this that creates all the fun plasma stuff such as huge electric and magnetic fields, [and] particle acceleration.”

Vulcan 20-20 will allow scientists to conduct astrophysics research in the lab – recreating the conditions of distant galaxies to analyse the inner workings of the likes of stars or gas clouds, or how matter might behave when exposed to particular temperatures and densities. The field of study is driven by a desire to investigate the cosmos, explains Alex Robinson, the CLF’s lead theoretical plasma physicist. Astrophysical research is usually “observational”, he says. “You’re pointing some sort of telescope at it, and you see various things. But this then begs the question of what’s really going on.” The hope is that conducting experiments with a laser of such power will, for the first time, allow “really rigorous tests of whether certain theories could ever work or not”.The UK's Vulcan laser, now being dismantled to be replaced by a more powerful device (Credit: Central Laser Facility)

The UK’s Vulcan laser, now being dismantled to be replaced by a more powerful device

Among the mysteries they’re hoping to investigate in Oxford are the origins of magnetic fields, which surround the majority of substantial objects in the Universe, like stars and planets. “Why are those magnetic fields there? It’s not completely obvious,” Robinson says, and no observation can ever really go back and test why they first came into existence. One such testing method might involve merging matter to create shockwaves, and adding manufactured turbulence, such as the kinds caused by the likes of molecular clouds, planets and dust, to see whether that “could give rise to magnetic fields”. 

Other experiments will explore the origins of cosmic rays (high energy particles that can travel almost at the speed of light), how jets (sprays of particles that shoot out from high-energy collisions) are formed, and the structure inside giant planets.

Researchers will also use the Vulcan 20-20 laser to investigate the formation of new materials. A form of boron nitride, a material harder than diamond, has potentially been found to be metastable – created in very high pressure and intensity conditions manufactured in the lab, that can afterwards survive at ambient temperatures. “And then the question is, what other materials could you make in the same way?” says Robinson. “Would they have fantastic electronic or optical properties? I don’t know. But at least there’s a nugget there telling us that there is something that’s worth exploring.”

Achieving fusion

Nuclear fusion is also on the ultra-high powered lasers’ hit list. In July, researchers at Lawrence Livermore National Laboratory’s National Ignition Facility, in California, used lasers to achieve a net gain in energy for a second time. Following the centre’s original breakthrough last December, the experiment this year created a higher energy yield than the first, again raising hopes that clean energy might replace our existing power sources. (Fusion reactions don’t release greenhouse gases or radioactive waste.) 

Fusion has also been one of the key areas of study at the Extreme Light Infrastructure for Nuclear Physics (ELI-NP) hub in Măgurele, Romania – which at 10-petawatt strength retains the title of the world’s most powerful laser (Mourou, its director and namesake of the University of Michigan facility, said its creation is “on a par with a lunar landing, where failure is not an option”).

Over the past year, the Romanian laser’s operator has begun partnering with private companies to develop technology that might fuel the world’s first commercial fusion plants. Using the “Chirped Pulse Amplification” technique that earned Mourou and Donna Strickland the Nobel Prize in Physics in 2018, laser pulses will be stretched, reducing their peak power, before being amplified and compressed again. This “pretty much changed the face of laser development in its entirety”, Clarke says, allowing far higher intensities to be reached with a low power (higher ones risk destroying “the quality of the laser pulse and even the laser chain itself if you push it too hard,” says Clarke).

Their research into the physical processes of this interaction is expected to be published in three years, prior to the building of their first commercial fusion power plants in the 2030s.

Bigger is better?

Physicists are keen to emphasise the collaborative nature of the field – but size still remains something of a bragging point. According to Chang Hee Nam, director of the Center for Relativistic Laser Science (CoReLS) in South Korea and professor at Gwangju Institute of Science and Technology, their laser currently “holds the highest intensity laser record” in the world, reaching 10^23 W/sq cm – or an intensity as powerful as all light on Earth focused to just over one micrometre, or less than a fiftieth the diameter of a human hair.

The South Korean scientists are using the technology to explore, among other things, proton therapy – a cancer treatment that targets positively charged beams at patients’ tumours.

Research that can yield new medical applications, along with testing out century-old ideas about the state of the Universe, have been well explored on CoReLS’ four-petawatt machine – but the team aren’t stopping there. Nam says that “we are now pushing to have a higher petawatt laser; we are preparing some proposals for a 25 petawatt laser beam”. If commissioned within the next six years as he hopes, it will dwarf the as-yet-unbuilt Vulcan 20-20.

Still, Vulcan’s Clarke says that power and intensity is not everything. The most important metric now is “what can you do with it? What science are you driving? What are you going to get out of it?” These lasers, and the researchers working on them, care about one thing above all else, he says. “It’s about building it right, and using it right.”

Scientists Fire Lasers at the Sky to Control Lightning

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Laser beams could be used to deflect lightning strikes from vulnerable places such as airports and wind farm

Scientists Fire Lasers at the Sky to Control Lightning
A new “laser lightning rod” in action.

Lightning strikes about 40 million times in the U.S. each year. This natural phenomenon is terrifyingly random, and we rely mainly on lightning rods—a nearly 300-year-old technology—to deal with it. But researchers are finally working on a more 21st-century solution: laser beams.

Pioneered by Benjamin Franklin, the lightning rod works well to defend a building. But it only has a limited ability to protect larger swaths of land or sprawling facilities such as wind farms, airports and rocket launch pads. So a team of scientists has tried using a high-powered laser to guide lightning strikes atop a mountain in Switzerland. This “laser lightning rod” technique that could one day deflect strikes from important large-scale infrastructure. The results of the researchers’ new study were published this week in Nature Photonics.

“What they’ve done is very impressive,” says Jerry Moloney, an optical scientist at the University of Arizona, who was one of the early pioneers of this laser application but was not involved in the study. It’s “a very, very sophisticated setup.”

Lightning occurs when friction among water droplets creates a static electric charge within clouds, usually during storms. This electricity builds before being discharged in a giant spark, which can travel between the cloud and the ground, either upward or downward, following the path of least resistance. Regular lightning rods are made of conductive metal, and they provide a preferential point for the lightning to strike and then safely channel the charge around a building and into the ground. But metal is not the only way to attract lightning away from more vulnerable targets.

Laser lightning rod
The laser lightning rod fires 1,000 times a second.

In the new experiment, a high-powered laser turns a column of air into an electrical conductor. When the laser is fired, the air molecules in the beam’s path are stripped of their electrons in a process called ionization. This transforms the air, which is normally insulating, into an attractive point for the lightning to hit—effectively creating a giant, temporary and controllable lightning rod in the sky above the area to be protected. Scientists had dreamed of building laser lightning rods for decades, but previous experiments had largely failed. Lasers that were available at the time could only pulse around 10 times per second, explains Aurélien Houard, a physicist at the École Polytechnique in France and first author of the study. That rate is too slow to keep an air column ionized. The new laser can fire 1,000 times per second, with each pulse lasting one trillionth of a second.

“You can burn stone if you want with this laser,” says Houard. The laser has an average power of one kilowatt (roughly the amount of electricity required to operate a large oven or refrigerator), says the paper’s senior author Jean-Pierre Wolf, a physicist at the University of Geneva.

The researchers tested their laser’s ability to draw lightning atop Säntis, a prominent peak in the Swiss Alps that was chosen because lightning often hits a telecommunication tower at its summit. There, during the summer of 2021, the team observed 16 lightning strikes—four of which occurred while the laser was powered on. And in all four cases, sensors—either a high-speed camera or a high-frequency electromagnetic wave detector—captured the lightning following the beam’s path. The results are preliminary for now, and the authors hope to fine-tune the technique with more data from future studies.

“The next step will be closer to the real-world applications,” Wolf says, “basically redoing this experiment, say, close to a launching pad or close to an airport.”

Lightning strikes at airports are an “ongoing issue,” and they not only delay flights but can also injure or kill employees and travelers, says Irene Miller, an assistant professor of aviation at Southern Illinois University, who was not involved in the new study. Most airports currently rely on early-warning systems to prevent planes from taxiing or landing when the risk of a strike is high.

It remains unclear how laser lightning rod technology might be adapted to this setting because even tiny lasers aimed at the sky are notoriously dangerous to pilots. During their recent mountaintop experiment, the researchers worked with aviation authorities to designate a no-fly zone around Säntis. One way to address such concerns could be to adjust the laser’s wavelength and power, and the study authors hope to explore that idea in future projects. For now, though, Benjamin Franklin’s innovation will have to do.

Nobel Prize in Physics won by scientists using lasers to solve the universe’s smallest mysteries

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Winners Arthur Ashkin, Gérard Mourou and Donna Strickland helped develop technology dreamed up in science fiction that led to breakthroughs such as eye surgery.

The 2018 Nobel Prize in Physics has been given to scientists who used lasers to solve some of the universe’s smallest mysteries.

The award was given to Arthur Ashkin and the other half jointly to Gérard Mourou and Donna Strickland.

Ashkin was given the prize for “optical tweezers and their application to biological systems”, the committee wrote. Those optical tweezers use lasers to grab particles, atoms, viruses and other living cells.

That in turn allowed for something from science fiction’s dreams: using light to move physical objects around. He found that he could push small particles towards the centre of the beam and hold them there.

As well as being a stunning breakthrough in itself, the discovery led to further work as scientists could use the tweezers to investigate the tiny processes that power the universe. They can grab bacteria without harming them, for instance, allowing Ashkin and other scientists to investigate what the committee called the “machinery of life”.

Mourou and Strickland allowed mankind to create the shortest and most intense laser pulses ever seen. With a technique called chirped pulse amplification, or CPA, they allowed for high-intensity lasers, of the kind that are used today millions of times to carry out corrective eye surgeries.

Their discoveries also laid the foundation for the work done by Ashkin. And the full implications of their work have still not yet been found.

“The innumerable areas of application have not yet been completely explored,” the committee wrote. “However, even now these celebrated inventions allow us to rummage around in the microworld in the best spirit of Alfred Nobel – for the greatest benefit to humankind.”

Strickland is the first woman to be named a Nobel laureate since 2015. She is also only the third to have won the physics prize, with the first being Marie Curie in 1903.

Smokin’ in the OR

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Society Aims to Protect Personnel, Patients From Harmful Fumes

 

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The days of lighting up a cigarette in airplanes and restaurants may be of a bygone era, but when it comes to the operating room, the exposure to hazardous smoke continues to flourish.

While recent studies show that the latest “silent killer” may be a conventional day in the OR, the Association of periOperative Registered Nurses Go Clear program aims to bring awareness to the harmful effects of surgical smoke and introduces guidelines to protect the health of practitioners and their patients.

The Hidden Dangers of Surgical Smoke

The dangers of inhaling surgical smoke—the byproduct generated from the use of lasers, electrosurgical pencils and ultrasonic devices—have been acknowledged by the medical community at large since the mid-70s. However, shockingly few health care facilities have hard-set requirements when it comes to utilizing scavenging systems to reduce exposure.

“We’ve evolved into a false sense of security that the smoke generated from laser surgery isn’t harmful, but the reality is, this stuff is in a different league than cigarettes,” said Mary J. Ogg, MSN, RN, CNOR, Senior Perioperative Practice Specialist at AORN.

From toxic gases, vapors, and dead and live cellular material including blood fragments and viruses, surgical smoke can wreak biological, carcinogenic, chemical and cytotoxic havoc on practitioners and their patients. To boot, its unique chemical composition makes it particularly hazardous.

“Particles generated by surgical energy devices can be smaller than 1.1 microns in size, meaning they are capable of bypassing the nasopharynx and trachea and can be deposited into the alveoli, the gas exchange regions of the lungs,” Ms. Ogg said. “Even the human papillomavirus (HPV) or the human immunodeficiency virus (HIV) have the potential to be detected in laser plume.”

A 2012 study conducted at the Royal Devon and Exeter NHS Foundation Trust illustrated that the lungs may pay a steep price for a job well done in the OR.

In an effort to quantify the exposure to surgical smoke within a plastic surgery unit, the study examined six human and 78 porcine tissue samples to find the mass of tissue ablated during five minutes of monopolar diathermy. The total daily duration of diathermy within the plastic surgery unit was electronically recorded over a two-month period. The study concluded that the smoke produced daily was “equivalent to 27-30 cigarettes” (J Plast Reconstr Aesthet Surg 2012;65:911-916).

Plastic surgeon Lisa M. Hunsicker, MD, FACS, from Denver, noted that the consequences of long hours in the OR have started to take a toll on her personal health.

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“When I work by myself, we use suction retractors. But this has only been available for the past few years,” she lamented. “I’ve been operating for 22 years now, mostly without these tools. I was diagnosed with asthma in 2013. Lung cancer and pulmonary issues are definitely a top concern for me.”

Assessing the Risk for Patients

It goes without saying that patients are a fundamental component of the OR, and when it comes to exposure to surgical smoke, they are not in the clear.

A 2014 study conducted in Poland examined the chemical composition of smoke formed in the abdominal cavity in patients undergoing laparoscopic cholecystectomy. Analysis of the smoke produced during the procedure revealed higher concentrations of a wide variety of potentially toxic chemicals, including benzene, toluene, xylene, dioxins and other substances. The study concluded that “all patients undergoing laparoscopic procedures are at risk of absorbing and excreting smoke by-products” (Int J Occup Med Environ Health 2014;27:314-325).

“Even patients in other rooms sometimes ask, ‘What’s that smell?’” Ms. Ogg said. “Many can detect carbon monoxide from minimally invasive, microscopic surgery happening down the hall.”

Why Aren’t We Doing Anything?

In 1996, the National Institute for Occupational Safety and Health released a hazard alert, warning facilities of the toxicity of surgical plume and presenting several methods of control. But over two decades later, its warnings are largely ignored; surgical smoke continues to be accepted as part of the “chemical soup” that is present during the care of perioperative patients. The lack of alarm begs the question: Where are we going wrong?

“The main crux is that there’s a complete lack of education,” Ms. Ogg said. “Half of health care professionals do not have any education when it comes to understanding the effects of surgical smoke. And as always, there’s a resistance to change.”

She added that while many hospitals have the proper evacuation equipment (evacuator filters, tubing and wands), some practitioners are not even aware that these tools are at their disposal.

“There was an instance in one hospital, where [they owned] a smoke evacuator in every single room, but no one in the hospital even knew they were there, and they went unused. Most of these tools are not a burden to utilize, and yet, we remain resistant.”

Current protocol dictates that it is up to the individual practitioner to take precaution to evacuate surgical smoke, meaning that a decision made by the surgeon may put everyone else in the room—including the nurses, the anesthesiologist and the patient—at risk.

“From what I’ve seen, no one takes precautions,” Dr. Hunsicker said. “My general surgeon partners still won’t use them—they don’t value me, or themselves. We need OSHA [Occupational Safety and Health Administration] to come in and assess the pollution in the OR and document levels, then calculate risks. We need to assess the situation as we would a chemical plant. It’s an occupational health hazard.”

AORN Go Clear Program

Recognizing that the evacuation of surgical smoke should be an administrative buy-in for protecting patients and the individuals who work in ORs, AORN created the Go Clear surgical smoke-free recognition program, aiming to provide comprehensive guidelines for health care facilities. Participating facilities are given one of three designations—bronze, silver and gold—and are rated on education performance, smoke evacuation compliance, and ensuring that the facility has the proper OR equipment, namely, capture devices (wands and tubing), smoke evacuators and medical-surgical vacuums with in-line filters.

AORN’s core guidelines suggest that every health care organization should assess the perioperative risks of surgical smoke, determine hazard exposure, establish safe practices, and recommend that all perioperative team members should wear personal protective equipment (PPE) as secondary protection against residual surgical smoke.

The efficacy of PPE, however, is up for debate.

“None work,” Dr. Hunsicker noted. “You would need a self-contained suit with an alternate air source. The safest person in the OR is the patient, but only if they are intubated. They are breathing on a closed air circuit with an alternate air source.”

Outside of the Go Clear program’s mission to get more institutions on board with proper surgical plume evacuation, another cornerstone is to encourage practitioners to share their stories.

“OR nurses are twice as likely to suffer respiratory symptoms as the general population,” Ms. Ogg said. “While we can’t make a direct correlation, there might be something to hearing clusters of people say, ‘My nose is always running; my eyes are always tearing in the OR.’” She explained that as more health care practitioners tell their stories, more direct correlations can be made.

While progress is being made on an administrative level—the state of California is moving forward with legislation that would require all health care facilities to use scavenging systems—Ms. Ogg noted that far more work needs to be done.

“This is a cause that has become my lifelong commitment,” she said. “With the right combination of education and the right technology, smoke evacuation can become a seamless part of the everyday operating room.”

New Lasers Made of Blood Could Revolutionize Cancer Detection

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Scientists from the University of Michigan have engineered a better way to track tumors with a laser that uses human blood.

LASERS — NOT THAT KIND BUT COOLER

Optofluidics, including the use of lasers, is not a new technology. Simply put, it is the application of some form of light to a liquid that serves as an amplifier, projected unto a reflective cavity. This technology is often used in medical research and surgery, like the use of infrared in scanning and imaging.

A group of researchers thought of a way to refine this technology, producing lasers with human blood.

It’s not exactly like the lasers in Star Wars, but it’s just as cool.

Human blood and an FDA-approved fluorescent dye called indocyanine green (ICG) made all the difference.  ICG has been used for decades now in imaging retinal blood vessels in ophthalmology. But without blood, “it doesn’t work at all,” says Xudong (Sherman) Fan, speaking to New Scientist. Fan is a professor in Biomedical Engineering at the University of Michigan.

BETTER TUMOR IMAGING

The researchers shone a form of infrared light on a reflective cylinder containing human blood with ICG as the amplifying material. The result was bright. The blood shone with the light, as ICG glows when mixed with protein in plasma.

Alfred Pasieka/SPL

With the light reflected back out, the researchers were able to observe cell structures and minuscule changes within the blood on a molecular level. The resulting fluorescence produced better imaging than current and existing techniques. Since ICG works well with blood, tissues that have a higher concentration of blood vessels — like tumors — will shine brighter.

Once the technology is refined to work on humans, this will be very useful in early cancer detection. “Eventually, we are trying to do it in the human body,” says Fan, but they are ensuring that the laser output is lower than recommended safety limits. “You don’t want to burn the tissue.”

Lasers Could Hide Earth from Prying Aliens.

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We could use laser light to mask our transits across the sun and thus hide Earth from any intelligent aliens looking for planets to invade

http://www.scientificamerican.com/podcast/episode/lasers-could-hide-earth-from-prying-aliens/

Doctors Are Using Lasers To Treat People With Severe Psychological Conditions .

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An MRI of the brain. The cingulate cortex is highlighted

Geoff B Hall via Wikimedia Commons

In the middle of the 20th century, lobotomies were a relatively commontreatment for people with severe mental illnesses. The controversial procedure surgically destroyed neurons connecting a patient’s prefrontal cortex to the rest of the brain. Since the 1960s, the procedure has fallen out of favor. But recently neuroscientists have made headway with a more exact, less destructive version of a lobotomy using lasers, according to an article inWired.

The procedure that uses lasers is called an anterior cingulotomy and, for now, is only approved to treat Obsessive-Compulsive Disorder (OCD). A surgeon drills a tiny hole in the patient’s skull, then inserts a tiny blade into the brain to carve a pathway to the anterior cingulate cortex, a part of the brain that links emotions to physical tasks. Once the surgeon’s tools arrive at the right cluster of neurons, they fire up the laser, burning lesions into a small, specific area of gray matter. The laser essentially melts part of the brain, which is less damaging than hacking at it, as is done in traditional lobotomies.

There are lots of other ways to treat OCD, of course. Medication and therapy are the most common, but those don’t work at all for 30 to 60 percent of patients. As neuroscientists have pinpointed the parts of the brain that cause OCD, they’ve figured out where to direct more invasive treatments. Some have been working with deep brain stimulation, where a surgeon attaches electrodes to the ventral striatum, critical to rewards-based decision-making and crossroads for a lot of important neurological functions. But even the hardiest devices require maintenance, so sometimes these laser psychosurgeries are preferable.

So far the FDA has only approved surgeries to treat patients with OCD, for which they have a pretty high success rate—in one trial, 69 percent of patients had a full or partial response five years after treatment. But soon they may be approved to treat depression, as initial results seem to restore normal brain function to patients.

Lasers ignite ‘supernovae’ in the lab .

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One of the world’s most powerful laser facilities has been used to create tiny versions of supernova explosions in the laboratory. The goal of the research, which has been done by an international team of physicists, is to gain insight into one of the most energetic and unpredictable events in the universe. The researchers also hope that their experiments could lead to a better understanding of the role played by cosmic turbulence in creating the powerful magnetic fields seen in some atypical supernova remnants, such as Cassiopeia A.

Supernovae are massive stellar explosions that are triggered either when the fuel within a star reignites or its core collapses under extreme gravitational forces. The explosion expels most of the star’s material, which in turn sends out a shock wave that expands over long distances in interstellar space. The shock wave binds most of the ejected stellar material and other dust in its path, creating what is known as a supernova remnant (SNR). While most SNRs have regular, shell-like features, some, such as Cassiopeia A, have irregular and unexplained shapes. The Cassiopeia SNR is about 11,000 light-years from Earth and light from it first reached our planet 300 years ago. Optical images of the explosion reveal irregular “knotty” features, while X-ray and radio observations show the presence of magnetic fields about 100 times stronger than those in the surrounding interstellar medium.

An image of the lab-based "supernova" created using the lasers

Knotted shock

It is these oddities of Cassiopeia A that caught the attention of plasma physicist Gianluca Gregori of Oxford University and his team of international researchers. Gregori told physicsworld.com that the initial idea for the study came from conversations with astronomers about the problems in understanding the formation of magnetic fields in the universe. “Over a coffee break, we started realizing that perhaps we should try to perform a lab experiment to see if what we think is happening is really happening,” he says.

While the origin of the large magnetic field in the interior of Cassiopeia A is still unknown, one possibility is that the shock wave could have passed through a region of space that is filled with dense clumps or clouds of gas. “In Cassiopeia A, the probable explanation that we proposed is that the irregular feature is caused by the supernova shock being perturbed and fragmented by dense clouds that surrounds the star,” says Gregori.

It may sound surprising that a table-top laboratory experiment that fits inside an average room can be used to study astrophysical objects that are light years across
Gianluca Gregori, Oxford University

To test this idea, Gregori and colleagues decided to recreate a slightly smaller “bang”, devising a laboratory-based method to investigate this turbulence. “It may sound surprising that a table-top laboratory experiment that fits inside an average room can be used to study astrophysical objects that are light-years across,” says Gregori. The researchers used the Vulcan laser facility at the Rutherford Appleton Laboratory to recreate their SNRs. “Our team began by focusing three laser beams onto a carbon-rod target, not much thicker than a strand of hair, in a low-density gas-filled chamber,” says Jena Meinecke, an Oxford University graduate student who headed the experiment. When the rod is heated to a temperature of a few million degrees kelvin, it explodes. This creates an asymmetric shock wave that expands outwards through the argon gas, much like a real supernova in space.

Turbulent flows

In the experiments, the dense gas clumps or clouds that would surround an exploding star were simulated by placing a plastic grid 1 cm from the target. This disturbs the shock front and results in turbulent flow. The shock and the turbulent flow is captured a 300 billionth of a second after the laser shot, using a special imaging technique.

Gregori mentions that the team was lucky in that its meticulously planned experiment worked perfectly in the time available at the Vulcan facility. “Sometimes, even when you prepare for months, you encounter problems. This time all the diagnostics and the team were fantastic,” he exudes, pointing out that access to the laser is fairly competitive.

The researchers found that as the shock wave moved through the grid, turbulence and irregular features began to appear. “We found that the magnetic field is higher with the grid than without it,” says Gregori, explaining that the result “is consistent with both observations and numerical models of a shock wave passing through a ‘clumpy’ medium”. As higher magnetic fields imply a more efficient generation of radio and X-ray photons, the team’s results call into question the currently accepted idea that supernova explosions expand into uniformly distributed interstellar material.

Gregori points out that the research has an impact on more than just SNRs, because the amplification of magnetic field via turbulence applies to many astrophysical systems. “We know that there are magnetic fields, but we don’t know how they got there in the first place. The standard mechanism that is usually invoked is that tiny ‘seed’ fields were produced just after the Big Bang and then those fields were amplified by turbulence.”

Scientists hatch plan to laser-blast space junk.

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Scientists have come up with a very video game-like way to take out orbiting space debris using ground-based lasers.

space debris around EarthThis NASA image is an illustration of space debris.

It’s a junkyard out there. Researchers estimate that at least several hundred thousand pieces of space debris are stuck out in orbit around the planet, creating hazards for satellites and spacecraft. These pieces include everything from stray bolts to entire derelict satellites. If only we could blast them with lasers and take care of the problem. Oh wait, maybe we can.

The Australian government announced a $20 million Cooperative Research Centre that will investigate using lasers to locate, track, and remove space debris. The group will bring together partners from the government, academia, and aerospace industries. A total estimated investment of around $90 million is needed to bring the project to fruition. NASA’s Ames Research Center and Lockheed Martin are already on board.

“Everywhere humans have been in space, we leave some trash behind,” said Matthew Colless, director of the Australian National University Research School of Astronomy and Astrophysics at Mount Stromlo. “We now want to clean up space to avoid the growing risks of collisions and to make sure we don’t have the kind of event portrayed in ‘Gravity.'”

The idea of using lasers in the battle against space junk has been around for a while, but the latest thinking advances the concept. Scientists have already floated the idea of nudging junk out of the way of satellites using lasers. The Australian team would like to eventually use lasers to slow the orbit of objects until they fall into the atmosphere and burn up. The tracking component of the project would come first, however, in an attempt to prevent collisions that only create more pieces of junk.

If the laser plan comes to fruition, manning the lasers could become one of the most sought-after tech jobs in history. Perhaps the laser operators would be recruited from among expert video game players. It may be as close to a real-life Asteroids as anyone could hope for.