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Category: physics – Page 168

The mathematics that makes us realize we don’t know much: Behavior of spin glasses

Spin glasses are alloys formed by noble metals in which a small amount of iron is dissolved. Although they do not exist in nature and have few applications, they have nevertheless been the focus of interest of statistical physicists for some 50 years. Studies of spin glasses were crucial for Giorgio Parisi’s 2021 Nobel Prize in Physics.

The scientific interest of spin glasses lies in the fact that they are an example of a complex system whose elements interact with each other in a way that is sometimes cooperative and sometimes adversarial. The mathematics developed to understand their behavior can be applied to problems arising in a variety of disciplines, from ecology to machine learning, not to mention economics.

Spin glasses are , that is, systems in which individual elements, the spins, behave like small magnets. Their peculiarity is the co-presence of ferromagnetic-type bonds, which tend to align the spins, with antiferromagnetic-type bonds, which tend to orient them in opposite directions.

Scientists Tested Einstein’s Relativity on a Cosmic Scale, And Found Something Odd

Everything in the Universe has gravity – and feels it too. Yet this most common of all fundamental forces is also the one that presents the biggest challenges to physicists.

Albert Einstein’s theory of general relativity has been remarkably successful in describing the gravity of stars and planets, but it doesn’t seem to apply perfectly on all scales.

General relativity has passed many years of observational tests, from Eddington’s measurement of the deflection of starlight by the Sun in 1919 to the recent detection of gravitational waves.

Build Your Own Universe

Physicists agree, one day it may be possible for a person to create a universe. It won’t happen tomorrow, but the idea is in the works. There’s already one problem with the idea: If a universe is created, physicists say they wouldn’t know how to communicate with it.

What If Humanity Is Among The First Spacefaring Civilizations?

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Half of the universe is filled with expansionist alien civilizations, and it’s only a matter of time before they’ll reach us. OK, that sounded a little sensationalist. But it’s also the conclusion of a recent astrophysics paper. Let’s see how they figure this, and whether we should take it seriously.

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10 Paradoxes That Will Stretch Your Mind

As in physics, paradoxes in biology really are just unsolved puzzles. Enter Peto’s paradox. Biologist Richard Peto noticed in the 1970s that mice had a much higher rate of cancer than humans do, which doesn’t make any sense. Humans have over 1,000 times as many cells as mice, and cancer is simply a rogue cell that goes on multiplying out of control. One would expect humans to be more likely to get cancer than smaller creatures such as mice. This paradox occurs across all species, too: blue whales are much less likely to get cancer than humans, even though they have many more cells in their bodies.

Fermi paradox

Named after physicist superstar Enrico Fermi, the Fermi paradox is the contradiction between how likely alien life is in the universe and its apparent absence. Considering the billions of stars in the galaxy like the sun, the many Earth-like planets that must be orbiting some of those stars, the likelihood that some of those planets developed life, the likelihood that some of that life is as intelligent or more intelligent than humanity, the galaxy should be teeming with alien civilizations. This absence led Fermi to pose the question, “Where is everybody?” Some answers to that question are unfortunately a little disturbing.

Solar cells one-thousandth the size of human hair can resist space radiation

Earth’s low orbit is filling up, meaning radiation-tolerant cell designs are required as satellites head to higher orbits. Will these new ones do?

Scientists have developed a radiation-tolerant photovoltaic cell design that features an ultrathin layer of light-absorbing material. According to a new study published today (Nov .08) in the Journal of Applied Physics by AIP Publishing.

Significantly, the ultra-thin solar cells not only surpass earlier suggested thicker solar cells in resilience to irradiation; they also produce the same amount of power from converted sunlight after 20 years of use. Additionally, the novel photovoltaic cells could reduce load and considerably lower launch expenses. Barthel.

What is “early dark energy” and can it save the expanding Universe?

You can imagine starting at the beginning, evolving the Universe forward according to the laws of physics, and measuring those earliest signals and their imprints on the Universe to determine how it has expanded over time. Alternatively, you can imagine starting here and now, looking out at the distant objects as we see them receding from us, and then drawing conclusions as to how the Universe has expanded from that.

Both of these methods rely on the same laws of physics, the same underlying theory of gravity, the same cosmic ingredients, and even the same equations as one another. And yet, when we actually perform our observations and make those critical measurements, we get two completely different answers that don’t agree with one another. This is, in many ways, the most pressing cosmic conundrum of our time. But there’s still a possibility that no one is mistaken and everyone is doing the science right. The entire controversy over the expanding Universe could go away if just one new thing is true: if there was some form of “early dark energy” in the Universe. Here’s why so many people are compelled by the idea.

Scientists Solve an 80-Year-Old Physics Mystery

Contact electrification (CE) was humanity’s earliest and sole source of electricity until about the 18th century, but its real nature remains a mystery. Today, it is regarded as a critical component of technologies such as laser printers, LCD production processes, electrostatic painting, plastic separation for recycling, and more, as well as a major industrial hazard (damage to electronic systems, explosions in coal mines, fires in chemical plants) due to the electrostatic discharges (ESD) that accompany CE. A 2008 study published in Nature found that in a vacuum, ESDs of a simple adhesive tape are so powerful that they generate enough X-rays to take an X-ray image of a finger.

For a long time, it was believed that two contacting/sliding materials charge in opposing and uniform directions. However, after CE, it was discovered that each of the separated surfaces carries both (+) and (-) charges. The formation of so-called charge mosaics was attributed to experiment irreproducibility, inherent inhomogeneities of contacting materials, or the general “stochastic nature” of CE.

Should we abandon the multiverse theory? | Sabine Hossenfelder, Roger Penrose, Michio Kaku

What is driving the mulitverse theory? Are the multiverse stories only a sticky-plaster solution to the Big Bang theory problem? Leading thinkers Sabine Hossenfelder, Roger Penrose and Michio Kaku debate.

00:00 Introduction.
02:22 Michio Kaku | Multiverse theory has now dominating cosmology; it is unavoidable.
06:03 Sabine Hossenfelder | Believing in the multiverse is the logical equivalent to believing in God.
07:57 Roger Penrose | Universes are sequential and so are not independent worlds.
16:36 Theme 1 | Do scientifc theories need to be testable?
28:45 Theme 2 | Are tales of the multiverse solutions to the Big Bang theory in trouble?
42:49 Theme 3 | Will theories of the universe always be bound by untestable elements?

Multiverses are everywhere. Or at least the theory is. Everyone from physicists Stephen Hawking and Brian Greene to Marvel superheroes have shown their support for the idea. But critics argue that not only is the multiverse improbable, it is also fantasy and fundamentally unscientific as the theory can never be tested — a requirement that has defined science from its outset.

Should we reject the grand claims and leave multiverse theories to the pages of comic books? Are tales of the multiverse really sticking-plaster solutions for Big Bang theory in trouble? Or should we take multiverse theory as seriously as its proponents, and accept that modern science has moved beyond the bounds of experiment and into that of imagination?

#TheMultiverseFantasy #BigBangTheoryProblem #SpaceTimeContinuum.

Michio Kaku is the co-founder of string field theory and the author of several books including several New York Times best sellers such as ‘The God Equation: The Quest for a Theory of Everything became.’ He is also professor of theoretical physics in the City College of New York and CUNY Graduate Center.

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