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Category: physics – Page 295

“Holy Grail” –Proof of Cosmic Objects Without a Hard Surface Confined Within an Invisible Boundary

O,.o.

Albert Einstein described black holes as strange objects “where God divided by zero.” An international team of astrophysicists has now confirmed that black holes are a distinct “species” from neutron stars –comparable to black holes in mass and size but confined within a hard surface, unlike black holes, an exotic cosmic object without a hard surface predicted by Einstein’s theory of General Relativity that do not have a surface, and are confined within an invisible boundary, called an event horizon, from within which nothing, not even light, can escape.

Hidden in NASA Archival X-ray Data

Definitive proof of the existence of such objects, “a holy grail of modern physics and astronomy,’ reports the Tata Institute of Fundamental Research, has been achieved by an international team who revealed by far the strongest steady signature of stellar-mass black holes to date. Using the archival X-ray data from the now decommissioned astronomy satellite Rossi X-Ray Timing Explorer, that probed the extreme environments around white dwarfs, neutron stars, black holes, the team identified the effect of the lack of hard surface on the observed X-ray emission, and thus have found an extremely strong signature of accreting stellar-mass black holes.

Why disordered light-harvesting systems produce ordered outcomes

Scientists typically prefer to work with ordered systems. However, a diverse team of physicists and biophysicists from the University of Groningen found that individual light-harvesting nanotubes with disordered molecular structures still transport light energy in the same way. By combining spectroscopy, molecular dynamics simulations and theoretical physics, they discovered how disorder at the molecular level is effectively averaged out at the microscopic scale. The results were published on 28 September in the Journal of the American Chemical Society.

The double-walled light-harvesting nanotubes self-assemble from molecular building blocks. They are inspired by the multi-walled tubular antenna network of photosynthetic bacteria found in nature. The nanotubes absorb and transport light energy, although it was not entirely clear how. “The nanotubes have similar sizes but they are all different at the with the molecules arranged in a disordered way,” explains Maxim Pshenichnikov, Professor of Ultrafast Spectroscopy at the University of Groningen.

A Physicist Has Come Up With Math That Makes ‘Paradox-Free’ Time Travel Plausible

No one has yet managed to travel through time – at least to our knowledge – but the question of whether or not such a feat would be theoretically possible continues to fascinate scientists.

As movies such as The Terminator, Donnie Darko, Back to the Future and many others show, moving around in time creates a lot of problems for the fundamental rules of the Universe: if you go back in time and stop your parents from meeting, for instance, how can you possibly exist in order to go back in time in the first place?

It’s a monumental head-scratcher known as the ‘grandfather paradox’, but now a physics student Germain Tobar, from the University of Queensland in Australia, says he has worked out how to “square the numbers” to make time travel viable without the paradoxes.

Physicists Just Discovered a Brand New Type of Superconductor

Scientists have long theorised that there are other types of superconductor out there waiting to be discovered, and it turns out they were right: new research has identified a g-wave superconductor for the first time, a major development in this area of physics.

Superconductors are materials that offer no electrical resistance, so electricity can pass through them with close to 100 percent efficiency.

That sounds great when you think about the potential of super-efficient power grids that don’t lose energy to heat. But there’s a catch. Materials that are able to act in this way usually need to be cooled to ultra-low temperatures before the actual superconductivity starts happening.

Why there is no speed limit in the superfluid universe

Physicists from Lancaster University have established why objects moving through superfluid helium-3 lack a speed limit in a continuation of earlier Lancaster research.

Helium-3 is a rare isotope of helium, in which one neutron is missing. It becomes at extremely low temperatures, enabling unusual properties such as a lack of friction for moving objects.

It was thought that the of objects moving through was fundamentally limited to the critical Landau velocity, and that exceeding this speed limit would destroy the superfluid. Prior experiments in Lancaster have found that it is not a strict rule and objects can move at much greater speeds without destroying the fragile superfluid state.

Why Metallic Hydrogen Is the Holy Grail of High Pressure Physics

Making hydrogen a metal takes lot of pressure. But after a group of scientist’s lost the world’s first sample, the pressure is really on.

Is Jupiter the Reason for Life on Earth? — https://youtu.be/nsGRvnPL95I

Settling Arguments About Hydrogen With 168 Giant Lasers

“With gentle pulses from gigantic lasers, scientists at Lawrence Livermore National Laboratory in California transformed hydrogen into droplets of shiny liquid metal. Their research, reported on Thursday in the journal Science, could improve understanding of giant gas planets like Jupiter and Saturn whose interiors are believed to be awash with liquid metallic hydrogen.”

What in the World Is Metallic Hydrogen?
https://www.space.com/39370-what-is-bizarre-metallic-hydrogen.html
“On Earth, as we’ve seen, hydrogen’s behavior is straightforward. But Jupiter isn’’t Earth, and the hydrogen found in abundance within and beneath the great bands and swirling storms of its atmosphere can be pushed beyond its normal limits.”

Insulator-metal transition in dense fluid deuterium
http://science.sciencemag.org/content/361/6403/677
“The conditions in which hydrogen disassociates and becomes an atomic metal occur in high-energy-density environments, such as the interiors of giant planets and nuclear explosions. Celliers et al. trained 168 lasers on deuterium samples at the National Ignition Facility to measure the pressure and temperature conditions of the hydrogen transition.”

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Physicists Break 150-Year-Old Rule for Phase Behavior – Something Many Considered Impossible

Eindhoven University of Technology researchers found five different phases in mixtures of two substances.

Frozen water can take on up to three forms at the same time when it melts: liquid, ice, and gas. This principle, which states that many substances can occur in up to three phases simultaneously, was explained 150 years ago by the Gibbs phase rule. Today, researchers from Eindhoven University of Technology and University Paris-Saclay are defying this classical theory, with proof of a five-phase equilibrium, something that many scholars considered impossible. This new knowledge yields useful insights for industries that work with complex mixtures, such as in the production of mayonnaise, paint, or LCD’s. The researchers have published their results in the journal Physical Review Letters.

The founder of contemporary thermodynamics and physical chemistry is the American physicist Josiah Willard Gibbs. In the 1870s he derived the phase rule, which describes the maximum number of different phases a substance or mixture of substances can assume simultaneously. For pure substances, the Gibbs Phase Rule predicts a maximum of 3 phases.

Physicists Demonstrate How to Reverse of the Arrow of Time

Circa 2017

One of the more curious challenges in physics is to understand the nature of time. At the microscopic level, the laws of physics are symmetric with respect to time—they work just as well whether time runs forwards or backwards. But at the macroscopic level, processes all have a preferred direction. The great physicist Arthur Eddington called this the “arrow of time.”

Just why this arrow points in one direction but not the other is one of the great scientific puzzles. The standard answer is that the arrow of time follows from the Second Law of Thermodynamics—that disorder, or entropy, always increases in a closed system.

That’s why milk mixes easily in tea but never emerges from a brew, why scrambled eggs never spontaneously unscramble, and why your morning mug of coffee heats your hands as you hold it and not the other way around.

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