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Gizmorama - January 31, 2018

Good Morning,


Are you ready to enter the fourth dimension? Scientists are experimenting with the possibilities of discovering and entering that very dimension.

Learn about this and more interesting stories from the scientific community in today's issue.

Until Next Time,
Erin


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*-- Scientists find two ways to create 4D quantum Hall effect --*

Two teams of scientists have measured the effects of a fourth dimension in a pair of lab experiments. Scientists didn't discover an extra dimension, but they did show how materials might behave if there was one.

"We don't have four spatial dimensions," researcher Mikael Rechtsman, a physicist at Penn State University, told UPI.

Physicists have been interested in the quantum Hall effect since it was first described in the 1980s. The effect described the fixed, quantized nature of conductivity in 2D materials.

"This was surprising to physicists because you have disorder in a material -- between different samples you expect to have different fluctuations," Rechtsman said.

When materials move from 2D to 3D, the quantum Hall effect disappears, but using advanced mathematics, physicists showed -- in theory -- how the effect would reappear in a hypothetical fourth dimension.

Until now, the hypothetical fourth dimension was only a math formula. Rechtsman and his colleagues translated the effect to the material world. They did so by emulating a 4D material with an array of wavelengths. To create the wavelengths, scientists etched tiny tubed patterns into a piece of glass using a laser. The system is known as a waveguide.

"We were able to kind of code in the third and fourth dimensions, almost like we were seeing a shadow of four dimensions," Rechtsman said.

Another team was able to replicate the effect by emulating extra-dimensional materials with laser-trapped atoms.

The experiments were described in two separate papers published this month in the journal Nature.

Researcher Oded Zilberberg, a physicist at ETH Zurich in Switzerland, worked on both experiments. He said keeping them separate in his mind wasn't a problem.

"Due to the fact that the experiments were studying complementary but not overlapping aspects of the model, it was not too difficult," Zilberberg said. "In the paper-writing phase, I was trying not to mix the narratives of the two papers, which was more challenging."

Both Rechtsman and Zilberberg said the two experiments and their results complement each other.

The experiment using laser-trapped atoms showed the effect in the center, or bulk, of the emulated material, while the experiment using the optical array replicated the effect on the material's edge.

"In topological phases of matter there is an important principle of bulk-edge correspondence and the idea of studying both aspects of our proposed model using these complementary techniques, systems, and teams was appealing to everyone involved," Zilberberg said.

The experiments were more than just theoretical exercises.

"Our work offers an elegant way of interpreting very complex materials, a type of material where the atoms are arranged in a very complex, inscrutable way," Rechtsman said.

By interpreting complex materials as derived by higher dimensions, researchers could use the techniques deployed by Rechtsman, Zilberberg and their colleagues to translate them into a simpler 2D rendering.

"We have seen for the first time that 4D topological effects can be seen in our world," Zilberberg said. "We have opened a porthole for studying other such types of higher-dimensional phenomena that we may encounter in our three-dimensional reality."



*-- Pollution particles fuel large storms, research shows --*

New research suggests scientists have underestimated the importance of particulate matter as a driver of storm size and intensity.

Scientists have previously proven that aerosols, particles suspended in the atmosphere, can influence weather and climate. With their latest study -- published this week in the journal Science -- researchers with the Department of Energy's Pacific Northwest National Laboratory showed the smallest particles can encourage the formation and increase the intensity of storms.

"We showed that the presence of these particles is one reason why some storms become so strong and produce so much rain," PNNL researcher Jiwen Fan, lead author of the new study, said in a news release. "In a warm and humid area where atmospheric conditions are otherwise very clean, the intrusion of very small particles can make quite an impact."

In 2014 and 2015, scientists measured a range of climate-related variables, using ground-based and airborne instruments, in the Amazon. The research focused on a large swath rainforest, untouched except for the incursion of Manaus. With a population of 2 million, Manaus is the largest city in the Amazon.

The region offers scientists a unique opportunity to identify and isolate man-made impacts on climate and weather patterns.

Researchers used the data to explore possible links between thunderstorms and ultra fine particles, particles measuring less than 50 nanometers wide, a thousandth the width of a human hair.

When strong updrafts carry larger particles into the atmosphere, they can help seed high-altitude clouds that a play an important role in thunderstorm formation. But the newest research shows ultra fine particles can also trigger the formation of thunderstorms.

When large particles are in short supply at high altitudes, the tiny particles can combine with heat and humidity to generate especially large storm clouds.

The absence of large particle allows for an excess of water vapor. The tiny particles offer a condensation opportunities and encourage cloud formation. As the water condenses into millions of tiny droplets, heat is released, which drives powerful updrafts, further fueling cloud formation. Scientists have dubbed this process "invigorated convection."

"We've shown that under clean and humid conditions, like those that exist over the ocean and some land in the tropics, tiny aerosols have a big impact on weather and climate and can intensify storms a great deal," said Fan. "More broadly, the results suggest that from pre-industrial to the present day, human activity possibly may have changed storms in these regions in powerful ways."

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