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Archive for the ‘physics’ category: Page 7

Sep 3, 2022

Does the Past Still Exist?

Posted by in categories: education, mathematics, physics, space

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Albert Einstein taught us that space and time belong together to a common entity: space-time. This means that time becomes a dimension, similar to space, and has profound consequences for the nature of time. Most importantly it leads to what has been called the block universe, a universe in which all moments of time exist the same way together. The future, the present, and the past are the same, it is just our perception that suggests otherwise.

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Sep 3, 2022

Scientists Unravel “Hall Effect” Physics Mystery

Posted by in categories: computing, physics

A multinational group of scientists has made progress in the use of antiferromagnetic materials in memory storage devices.

Antiferromagnets are materials with an internal magnetic field induced by electron spin but virtually no external magnetic field. Since there is no external (or “long-range”) magnetic field, the data units, or bits, may be packed more densely inside the material, making them potentially useful for data storage.

The ferromagnets commonly utilized in typical magnetic memory devices are the opposite. These devices do have long-range magnetic fields produced by the bits that prevent them from being packed too tightly together since otherwise they would interact.

Sep 2, 2022

Physicists develop a linear response theory for open systems having exceptional points

Posted by in categories: energy, engineering, physics

Linear analysis plays a central role in science and engineering. Even when dealing with nonlinear systems, understanding the linear response is often crucial for gaining insight into the underlying complex dynamics. In recent years, there has been a great interest in studying open systems that exchange energy with a surrounding reservoir. In particular, it has been demonstrated that open systems whose spectra exhibit non-Hermitian singularities called exceptional points can demonstrate a host of intriguing effects with potential applications in building new lasers and sensors.

At an exceptional point, two or modes become exactly identical. To better understand this, let us consider how drums produce sound. The membrane of the drum is fixed along its perimeter but free to vibrate in the middle.

As a result, the membrane can move in different ways, each of which is called a mode and exhibits a different sound frequency. When two different modes oscillate at the same frequency, they are called degenerate. Exceptional points are very peculiar degeneracies in the sense that not only the frequencies of the modes are identical but also the oscillations themselves. These points can exist only in open, non-Hermitian systems with no analog in closed, Hermitian systems.

Sep 2, 2022

How The Penrose Singularity Theorem Predicts The End of Space Time

Posted by in categories: cosmology, physics, singularity

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The Nobel prize in physics this year went to black holes. Generally speaking. Specifically, it was shared by the astronomers who revealed to us the Milky Way’s central black hole and by Roger Penrose, who proved that in general relativity, every black hole contains a place of infinite gravity — a singularity. But the true impact of Penrose’s singularity theorem would is much deeper — it leads us to the limits Einstein’s great theory and to the origin of the universe.

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Sep 2, 2022

Physicists Broke The Speed of Light With Pulses Inside Hot Plasma

Posted by in categories: law, physics

Most of us grow up familiar with the prevailing law that limits how quickly information can travel through empty space: the speed of light, which tops out at 300,000 kilometers (186,000 miles) per second.

While photons themselves are unlikely to ever break this speed limit, there are features of light which don’t play by the same rules.

Manipulating them won’t hasten our ability to travel to the stars, but they could help us clear the way to a whole new class of laser technology.

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Sep 1, 2022

Dark Matter: The Situation has Changed

Posted by in categories: cosmology, physics

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Today I tell you how my opinion about dark matter has changed an why. Is modified gravity better or worse? What evidence speaks for one side or the other, and is the case really as clear-cut as many astrophysicists claim?

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Sep 1, 2022

Using magnetic and electric fields to emulate black hole and stellar accretion disks

Posted by in categories: computing, cosmology, mathematics, physics

A team of researchers at the Sorbonne University of Paris reports a new way to emulate black hole and stellar accretion disks. In their paper published in the journal Physical Review Letters, the group describes using magnetic and electric fields to create a rotating disk made of liquid metal to emulate the behavior of material surrounding black holes and stars, which leads to the development of accretion disks.

Prior research has shown that massive objects have a gravitational reach that pulls in gas, dust and other material. And since such massive objects tend to spin, the material they pull in tends to swirl around the object as it moves closer. When that happens, gravity exerted by materials in the swirling mass tends to coalesce, resulting in an . Astrophysicists have been studying the dynamics of accretion disks for many years but have not been able to figure out how angular momentum is transferred from the inner parts of a given accretion disk to its outer parts as material in the disk moves ever closer to the central object.

Methods used to study accretion disks have involved the development of math formulas, and real-world models using liquids that swirl like eddies. None of the approaches has proven suitable, however, which has led researchers to look for new models. In this new effort, the researchers developed a method to generate an accretion disk made of bits spinning in the air.

Aug 30, 2022

Philip Goff — “Did the Universe Design Itself?”

Posted by in categories: alien life, physics

There are a number of constants in the basic laws of physics and initial conditions of the universe that are such that, for life to be possible, the values of those constants needed to fall in an exceedingly narrow range. Many scientists and philosophers think there must be an explanation of why, of all the values they might have had, these constants have precisely the values needed in order for life to be possible. There are deep difficulties with both of the standard explanations of this ‘fine-tuning’ of the laws of nature: theism and the multiverse hypothesis. I will argue that if one adopts a certain form of panpsychism, one can explain the fine-tuning in terms of the mental capacities of the universe, and that this constitutes a significantly less problematic and significantly more parsimonious explanation of the fine-tuning.

Philip Goff is Associate Professor in philosophy at the Central European University in Budapest (a unique and wonderful institution). His main research interest is consciousness, although he also has a sideline in political philosophy (taxation, globalisation, social justice). He recently finished his first book, Consciousness and Fundamental Reality (published with Oxford University Press August 2017), which argues against materialism and defends panpsychism. He is now working on a book on these themes aimed at a general audience. He has written for The Guardian and Philosophy Now, and writes a blog at www.conscienceandconsciousness.com. www.philipgoffphilosophy.com @philip_goff

Aug 30, 2022

Astronomers have detected one of the biggest black hole jets in the sky

Posted by in categories: cosmology, physics

Luke barnes, lecturer in physics, western sydney university miroslav filipovic, professor, western sydney university ray norris, professor, school of science, western sydney university velibor velović, phd candidate, western sydney university.

Astronomers at Western Sydney University have discovered one of the biggest black hole jets in the sky.

Spanning more than a million light years from end to end, the jet shoots away from a black hole with enormous energy, and at almost the speed of light. But in the vast expanses of space between galaxies, it doesn’t always get its own way.

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Aug 30, 2022

Spectroscopy That Doesn’t Scratch the Surface

Posted by in categories: energy, physics

Researchers have demonstrated a way of measuring the electronic states of a material’s surface while avoiding signal contaminations from deeper layers.

The electronic states of a material’s surface might only be 2D, but they offer a depth of interesting physics. Such states, which are distinct from those of the material’s bulk, dominate many phenomena, such as electrical conduction, magnetism, and catalysis, and they are responsible for nontrivial surface effects found in topological materials and systems with strong spin-orbit interaction. Surface electronic states also control the properties of so-called 2D materials, such as graphene. To understand surface phenomena and harness them in practical devices, researchers chiefly rely on photoemission spectroscopy, which measures the energy and momentum of electrons emitted when photons hit the material. The high resolution with which electron energy and momentum can be characterized allows physicists to measure both the band structure and the density of states (DOS) in the few surface layers where escaping photoelectrons originate.

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