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Category: physics – Page 157

The second law of thermodynamics explains why some events in nature can never run in reverse, despite the fact that they do not violate other laws of physics. For example, you can crack an egg, yet that cracked egg will never spontaneously put itself back together. Interestingly, if an egg were to uncrack itself, it would not violate the conservation of energy, which states that the total energy content of a system must always remain the same. Obviously eggs don’t randomly put themselves back together, and many other events usually only move in one direction. The second law of thermodynamics explains why this occurs through the concept of entropy. Entropy can be thought of as a measure of disorder. If your room is messy, you can say it has high entropy. If your room is tidy, it has low entropy. The second law of thermodynamics states that the total amount of entropy in a closed system will always increase. Thus, the total amount of disorder in the universe will always increase. Although some processes do go from a high entropy state to a low entropy state, interactions with the environment will always result in a net increase of entropy. For example, a living organism is fairly organized, and so it would have low entropy. However, the way that organism interacts with its environment will increase the total amount of entropy. The second law explains why some events, such as uncracking an egg, can never occur because the total amount of entropy must always be increasing. Entropy also explains how heat moves from warm objects to cold objects. When you leave your coffee out for too long, it inevitably gets colder. That’s because heat can only move from hot to cold, and never in reverse. This occurs because entropy must always increase.

The concept of entropy, and the fact that most things in the universe only occur in one direction, has interesting implications for the flow of time. Time is a poorly understood aspect of our universe. Even the smartest scientists have a hard time providing a good definition for what time actually is. We humans generally perceive time as the passage of events. The past is composed of events that once occurred, the present is events that are occurring, and the future is events that have yet to occur. However, why does time seem to only flow in one direction? As far as scientists know, there are no laws of physics that state time must always move forward. Time obviously only runs in one direction, a concept called the arrow of time. The second law of thermodynamics may actually provide a reason for why there seems to be an arrow of time. Since entropy and disorder must always increase as a whole in the cosmos, events will only occur in one direction, and never in reverse.

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Scientists in Germany and the US have predicted the most topologically complex knot ever found in a protein using AlphaFold, the artificial intelligence (AI) system developed by Google’s DeepMind. Their complete analysis of the data produced by AlphaFold also revealed the first composite knots in proteins: topological structures containing two separate knots on the same string. If the discovered protein knots can be recreated experimentally it will serve to verify the accuracy of predictions made by AlphaFold.

Proteins can fold to form complex topological structures. The most intriguing of these are protein knots – shapes that would not disentangle if the protein were pulled from both ends. Peter Virnau, a theoretical physicist at Johannes Gutenberg University Mainz, tells Physics World that there are currently around 20 to 30 known knotted proteins. These structures, Virnau explains, raise interesting questions around how they fold and why they exist.

A protein’s shape can be closely linked with its function, but while there are a few theories on the functionality and purpose of protein knots there is little hard evidence to back these up. Virnau says that they might help to keep the proteins stable, by being particularly resistant to thermal fluctuations, for instance, but these are open questions. While protein knots are rare, they also appear to be highly preserved by evolution.

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A new study corrects an important error in the 3D mathematical space developed by the Nobel Prize-winning physicist Erwin Schrödinger and others, and used by scientists and industry for more than 100 years to describe how your eye distinguishes one color from another. The research has the potential to boost scientific data visualizations, improve TVs and recalibrate the textile and paint industries.

“The assumed shape of color space requires a paradigm shift,” said Roxana Bujack, a computer scientist with a background in mathematics who creates scientific visualizations at Los Alamos National Laboratory. Bujack is lead author of the paper by a Los Alamos team in the Proceedings of the National Academy of Sciences on the mathematics of color perception.

“Our research shows that the current mathematical model of how the eye perceives color differences is incorrect. That model was suggested by Bernhard Riemann and developed by Hermann von Helmholtz and Erwin Schrödinger—all giants in mathematics and physics—and proving one of them wrong is pretty much the dream of a scientist,” said Bujack.

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To form a celestial object, start with a gas cloud and add gravity. Then, it gets complicated.

Accretion is one of the most fundamental processes in the cosmos. It is a universal phenomenon triggered by gravity, and the process by which bits of matter accumulate and coalesce with more bits of matter. It works inexorably on all scales to attract and affix smaller things to bigger things, from the tiniest dust grains to supermassive black holes.

Accretion creates everything there is: galaxies, stars, planets, and eventually, us. It is the reason the universe is filled with a whole bunch of somethings instead of a whole lot of nothing.

The fact that matter tends to glom together may seem intuitive. But to scientists, accretion remains a mysterious topic, filled with unanswered questions.

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Science, Technology, Health, Physics, Chemistry stay Updated.

Scientists from The Australian National University (ANU) and James Cook University (JCU) have identified an “exquisite” natural mechanism that helps plants limit their water loss with little effect on carbon dioxide (CO2) intake—an essential process for photosynthesis, plant growth and crop yield.

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Analysing pendulum videos, the artificial intelligence tool identified variables not present in current mathematics.

An artificial intelligence tool has examined physical systems and not surprisingly, found new ways of describing what it found.

How do we make sense of the universe? There’s no manual. There’s no prescription.

At its most basic, physics helps us understand the relationships between “observable” variables – these are things we can measure. Velocity, energy, mass, position, angles, temperature, charge. Some variables like acceleration can be reduced to more fundamental variables. These are all variables in physics which shape our understanding of the world.

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In February 2020, four distinguished astrophysicists — Jonathan Carroll-Nellenback, Adam Frank, Jason Wright, Caleb Scharf — suggested that Earth may have remained unvisited by space-faring civilizations all the while existing in a galaxy of interstellar civilizations seeded by moving stars that spread alien life, offering a solution to the perplexing Fermi paradox. They concluded that a planet-hopping civilization could populate the Milky Way in as little as 650,000 years.

“It’s possible that the Milky Way is partially settled, or intermittently so; maybe explorers visited us in the past, but we don’t remember, and they died out,” says Jonathan Carroll-Nellenback, an astronomer at the University of Rochester and his collaborators in a 2019 study that suggests it wouldn’t take as long as thought for a space-faring civilization to planet-hop across the galaxy, because the orbits of stars can help distribute life, offering a new solution to the Fermi paradox. “The solar system may well be amid other settled systems; it’s just been unvisited for millions of years.”

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