the Quotes generation notion

Don't forget the person who stay with you.

Hare Krishna hare Krishna Krishna Krishna hare hare hare Rama hare Rama hare Rama

Hare Krishna

Light and sound waves reveal negative pressure, Hare Krishna hare Krishna hare ram ..

 

Negative pressure is a rare and challenging-to-detect phenomenon in physics. Using liquid-filled optical fibers and sound waves, researchers have now discovered a new method to measure it. In collaboration with the Leibniz Institute of Photonic Technologies in

Negative pressure is a rare and challenging-to-detect phenomenon in physics. Using liquid-filled optical fibers and sound waves, researchers at the Max Planck Institute for the Science of Light (MPL) in Erlangen have now discovered a new method to measure it. In collaboration with the Leibniz Institute of Photonic Technologies in Jena (IPHT), the scientists in the Quantum Optoacoustics research group, led by Birgit Stiller, can gain important insights into thermodynamic states.

As a physical quantity pressure is encountered in various fields: atmospheric pressure in meteorology, blood pressure in medicine, or even in everyday life with pressure cookers and vacuum-sealed foods. Pressure is defined as a force per unit area acting perpendicular to a surface of a solid, liquid, or gas. Depending on the direction in which the force acts within a closed system, very high pressure can lead to explosive reactions in extrem cases, while very low pressure in a closed system can cause the implosion of the system itself. Overpressure always means that the gas or liquid pushes against the walls of its container from the inside, like a balloon expanding when more air is added. Regardless of whether it's high or low pressure, the numerical value of pressure is always positive under normal circumstances.

However, liquids exhibit a peculiar characteristic. They can exist in a specific metastable state corresponding to a negative pressure value. In this metastable state, even a tiny external influence can cause the system to collapse into one state or another. One can imagine it as sitting at the top of a roller coaster: the slightest touch on one side or the other sends you hurtling down the tracks. In their current research, the scientists are examining the metastable state of liquids with negative pressure. To achieve this, the research team combined two unique techniques in a study published in Nature Physics to measure various thermodynamic states. Initially, tiny amounts -- nanoliters -- of a liquid were encapsulated in a fully closed optical fiber, allowing both highly positive and negative pressures. Subsequently, the specific interaction of optical and acoustic waves in the liquid enabled the sensitive measurement of the influence of pressure and temperature in different states of the liquid. Sound waves act as sensors for examining negative pressure values, exploring this unique state of matter with high precision and detailed spatial resolution.

The influence of negative pressure on a liquid can be envisioned as follows: According to the laws of thermodynamics, the volume of the liquid will decrease, but the liquid is retained in the glass fiber capillary by adhesive forces, much like a water droplet sticking to a finger. This results in a "stretching" of the liquid. It is pulled apart and behaves like a rubber band being stretched. Measuring this exotic state typically requires complex equipment with heightened safety precautions. High pressures can be hazardous endeavors, particularly with toxic liquids. Carbon disulfide, used by the researchers in this study, falls into this category. Due to this complication, previous measurement setups for generating and determining negative pressures have required significant laboratory space and even posed a disturbance to the system in the metastable state. With the method presented here, the researchers have instead developed a tiny, simple setup in which they can make very precise pressure measurements using light and sound waves. The fiber used for this purpose is only as thick as a human hair.

"Some phenomena which are difficult to explore with ordinary and established methods can become unexpectedly accessible when new measurement methods are combined with novel platforms. I find that exciting," says Dr. Birgit Stiller, head of the Quantum Optoacoustics research group at MPL. The sound waves used by the group can detect temperature, pressure, and strain changes very sensitively along an optical fiber. Furthermore, spatially resolved measurements are possible, meaning that the sound waves can provide an image of the situation inside the optical fiber at centimeter-scale resolution along its length. "Our method allows us to gain a deeper understanding of the thermodynamic dependencies in this unique fiber-based system," says Alexandra Popp, one of the two lead authors of the article. The other lead author, Andreas Geilen, adds: "The measurements revealed some surprising effects. The observation of the negative pressure regime becomes abundantly clear when looking at the frequency of the sound waves."

The combination of optoacoustic measurements with tightly sealed capillary fibers enables new discoveries regarding the monitoring of chemical reactions in toxic liquids within otherwise difficult-to-investigate materials and microreactors. It can penetrate new, hard-to-access areas of thermodynamics. "This new platform of fully sealed liquid core fibers provides access to high pressures and other thermodynamic regimes," says Prof. Markus Schmidt from IPHT in Jena, and Dr. Mario Chemnitz, also from IPHT in Jena, emphasizes: "It is of great interest to investigate and even tailor further nonlinear optical phenomena in this type of fiber." These phenomena can unlock previously unexplored and potentially new properties in the unique thermodynamic state of materials. Birgit Stiller concludes: "The collaboration between our research groups in Erlangen and Jena, with their respective expertise, is unique in gaining new insights into thermodynamic processes and regimes on a tiny and easy-to-handle optical platform."

hare krishna hare krishna krishna krishna hare hare ....

Down goes antimatter! Gravity's effect on matter's elusive twin is revealed >><< Hare Krishna ..Hare Krishna...

 

Landmark CERN experiment may help explain why antimatter seemingly lost out in the early universe

September 27, 2023

National Science Foundation:

For the first time, in a unique laboratory experiment at CERN, researchers have observed individual atoms of antihydrogen fall under the effects of gravity. In confirming antimatter and regular matter are gravitationally attracted, the finding rules out gravitational repulsion as the reason why antimatter is largely missing from the observable universe.

If you dropped antimatter, would it fall down or up? In a unique laboratory experiment, researchers have now observed the downward path taken by individual atoms of antihydrogen, providing a definitive answer: antimatter falls down.

In confirming antimatter and regular matter are gravitationally attracted, the finding also rules out gravitational repulsion as the reason why antimatter is largely missing from the observable universe.

Researchers from the international Antihydrogen Laser Physics Apparatus (ALPHA) collaboration at CERN in Switzerland published their findings today in the journal Nature, an effort supported by more than a dozen countries and private institutions, including the U.S. through the joint U.S. National Science Foundation/Department of Energy Partnership in Basic Plasma Science and Engineering program.

"The success of the ALPHA collaboration is a testament to the importance of teamwork across continents and scientific communities," says Vyacheslav "Slava" Lukin, a program director in NSF's Physics Division. "Understanding the nature of antimatter can help us not only understand how our universe came to be but can enable new innovations never before thought possible -- like positron emission tomography (PET) scans that have saved many lives by applying our knowledge of antimatter to detect cancerous tumors in the body."

Matter's elusive, volatile twin

Beyond the imagined antimatter-fueled warp drives and photon torpedoes of Star Trek, antimatter is completely real, yet mysteriously scarce.

"Einstein's theory of general relativity says antimatter should behave exactly the same as matter," said University of California, Berkeley plasma physicist and ALPHA collaboration member Jonathan Wurtele. "Many indirect measurements indicate that gravity interacts with antimatter as expected" he added, "but until the result today, nobody had actually performed a direct observation that could rule out, for example, antihydrogen moving upwards as opposed to downwards in a gravitational field."

Our bodies, the Earth, and most everything else scientists know about in the universe are overwhelmingly made of regular matter consisting of protons, neutrons, and electrons, like atoms of oxygen, carbon, iron and the other elements of the periodic table.

Dropping an antimatter banger

"Broadly speaking, we're making antimatter and we're doing a Leaning Tower of Pisa kind of experiment," said Wurtele, referring to their experiment's simpler intellectual ancestor, Galileo's perhaps apocryphal 16th century experiment demonstrating identical gravitational acceleration of two simultaneously dropped objects of similar volume but different mass. "We're letting the antimatter go, and we're seeing if it goes up or down."

For the ALPHA experiment, the antihydrogen was contained within a tall cylindrical vacuum chamber with a variable magnetic trap, called ALPHA-g. The scientists reduced the strength of the trap's top and bottom magnetic fields until the antihydrogen atoms could escape and the relatively weak influence of gravity became apparent.

As each antihydrogen atom escaped the magnetic trap, it touched the chamber walls either above or below the trap and annihilated, which the scientists could detect and count.

The researchers repeated the experiment more than a dozen times, varying the magnetic field strength at the top and bottom of the trap to rule out possible errors. They observed that when the weakened magnetic fields were precisely balanced at the top and bottom, about 80% of the antihydrogen atoms annihilated beneath the trap -- a result consistent with how a cloud of regular hydrogen would behave under the same conditions.

Thus, gravity was causing the antihydrogen to fall down.

The matter/antimatter mystery

Despite some modest sources of antimatter -- like positrons emitted from the decay of potassium, even within a banana -- scientists do not see much of it in the universe. However, the laws of physics predict antimatter should exist in roughly equal amounts as regular matter. Scientists call that conundrum the baryogenesis problem.

One potential explanation is that antimatter was gravitationally repelled by regular matter during the big bang, although the new findings suggest that theory no longer seems plausible.

"We've ruled out antimatter being repelled by the gravitational force as opposed to attracted," said Wurtele. That doesn't mean there isn't a difference in the gravitational force on antimatter, he adds. Only a more precise measurement will tell.

The ALPHA collaboration researchers will continue to probe the nature of antihydrogen. In addition to refining their measurement of the effect of gravity, they are also studying how antihydrogen interacts with electromagnetic radiation through spectroscopy.

"If antihydrogen were somehow different from hydrogen, that would be a revolutionary thing because the physical laws, both in quantum mechanics and gravity, say the behavior should be the same," said Wurtele. "However, one doesn't know until one does the experiment."