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Topic Review
Quantum Reality
Quantum Reality is a 1985 popular science book by physicist Nick Herbert, a member the Fundamental Fysiks Group which was formed to explore the philosophical implications of quantum theory. The book attempts to address the ontology of quantum objects, their attributes, and their interactions, without reliance on advanced mathematical concepts. Herbert discusses the most common interpretations of quantum mechanics and their consequences in turn, highlighting the conceptual advantages and drawbacks of each.
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  • 30 Nov 2022
Topic Review
(486958) 2014 MU69
(486958) 2014 MU69, previously designated PT1 and 1110113Y, and nicknamed Ultima Thule by the New Horizons team, is a trans-Neptunian object from the Kuiper belt located in the outermost regions of the Solar System. It was discovered by astronomers using the Hubble Space Telescope on 26 June 2014. The irregular shaped classical Kuiper belt object is a suspected contact binary or close binary system and measures approximately 30 kilometers (19 miles) in diameter. In August 2015, this object was selected as the next target for the New Horizons probe shortly after it had visited Pluto. The flyby will occur on 1 January 2019, which will make it the farthest object in the Solar System ever to be visited by a spacecraft. After four course changes in October and November 2015, New Horizons is on course toward 2014 MU69. On 13 March 2018, NASA announced that (486958) 2014 MU69 would receive the nickname Ultima Thule. The decision was based on the results of a public voting campaign. Ultima Thule /ˈθuːliː/, or Ultima for short, serves as an unofficial name for the object until the IAU decides on an official name at some point after the flyby.
  • 1.0K
  • 19 Oct 2022
Topic Review
Beta (Plasma Physics)
The beta of a plasma, symbolized by β, is the ratio of the plasma pressure (p = n kB T) to the magnetic pressure (pmag = B²/2μ0). The term is commonly used in studies of the Sun and Earth's magnetic field, and in the field of fusion power designs. In the fusion power field, plasma is often confined using strong magnets. Since the temperature of the fuel scales with pressure, reactors attempt to reach the highest pressures possible. The costs of large magnets roughly scales like β½. Therefore, beta can be thought of as a ratio of money out to money in for a reactor, and beta can be thought of (very approximately) as an economic indicator of reactor efficiency. For tokamaks, betas of larger than 0.05 or 5% are desired for economically viable electrical production. The same term is also used when discussing the interactions of the solar wind with various magnetic fields. For example, beta in the corona of the Sun is about 0.01.
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  • 08 Oct 2022
Biography
Kameshwar C. Wali
Kameshwar C. Wali (born October 15, 1927) is the Distinguished Research Professor of Physics Emeritus[1] at Syracuse University's College of Arts and Sciences. He is a specialist in high energy physics, particularly symmetries and dynamics of elementary particles,[2] and as the author[3] of Chandra: A Biography of S. Chandrasekhar[4] and Cremona Violins: a physicist's quest for the secrets of St
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  • 22 Nov 2022
Biography
Erich Kretschmann
Erich Justus Kretschmann (14 July 1887 – 1973) was a Germany physicist.[1] Kretschmann was born in Berlin. He obtained his PhD at Berlin University in 1914 with his dissertation entitled "Eine Theorie der Schwerkraft im Rahmen der ursprünglichen Einsteinschen Relativitätstheorie"[2] (A theory of gravity in the framework of the original Einstein theory of relativity). His advisors were Max
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  • 08 Dec 2022
Topic Review
Riemannian Metric and Lie Bracket in Computational Anatomy
Computational anatomy (CA) is the study of shape and form in medical imaging. The study of deformable shapes in computational anatomy rely on high-dimensional diffeomorphism groups [math]\displaystyle{ \varphi \in \operatorname{Diff}_V }[/math] which generate orbits of the form [math]\displaystyle{ \mathcal{M} \doteq \{ \varphi \cdot m \mid \varphi \in \operatorname{Diff}_V \} }[/math]. In CA, this orbit is in general considered a smooth Riemannian manifold since at every point of the manifold [math]\displaystyle{ m \in \mathcal{M} }[/math] there is an inner product inducing the norm [math]\displaystyle{ \| \cdot \|_m }[/math] on the tangent space that varies smoothly from point to point in the manifold of shapes [math]\displaystyle{ m \in \mathcal{M} }[/math]. This is generated by viewing the group of diffeomorphisms [math]\displaystyle{ \varphi \in \operatorname{Diff}_V }[/math] as a Riemannian manifold with [math]\displaystyle{ \| \cdot \|_\varphi }[/math], associated to the tangent space at [math]\displaystyle{ \varphi \in\operatorname{Diff}_V }[/math] . This induces the norm and metric on the orbit [math]\displaystyle{ m \in \mathcal{M} }[/math] under the action from the group of diffeomorphisms.
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  • 25 Oct 2022
Biography
Watt W. Webb
Watt W. Webb is known for his co-invention (with Winfried Denk and Jim Strickler) of Multiphoton microscopy in 1990. Professor Watt W. Webb’s undergraduate studies at MIT in Business and Engineering Administration for his SB degree in 1947 led him to engineering research and development at Union Carbide Corporation Research Laboratories until 1952, then back to MIT for his ScD in Metallurgy
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  • 12 Dec 2022
Topic Review
SpaceIL
SpaceIL is an Israeli nonprofit organization, established in 2011, that was competing in the Google Lunar X Prize (GLXP) to land a spacecraft on the Moon. The contest declared no winner, but SpaceIL still aims to launch the spacecraft in 2019. SpaceIL team was formed as a nonprofit organization wishing to promote scientific and technological education in Israel. Its total budget is estimated at US$70 million, provided mainly by philanthropists and the Israel Space Agency (ISA).
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  • 24 Oct 2022
Topic Review
On Sizes and Distances
On Sizes and Distances (of the Sun and Moon) (Περὶ μεγεθῶν καὶ ἀποστημάτων [ἡλίου καὶ σελήνης], Peri megethon kai apostematon) is a text by the ancient Greek astronomer Hipparchus. It is not extant, but some of its contents have been preserved in the works of Ptolemy and his commentator Pappus of Alexandria. Several modern historians have attempted to reconstruct the methods of Hipparchus using the available texts.
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  • 20 Oct 2022
Biography
Shin-Tson Wu
Shin-Tson Wu, (Chinese:吳詩聰) is an American physicist and inventor. He is currently a Pegasus professor at CREOL, The College of Optics and Photonics, University of Central Florida. Wu's contributions to liquid-crystal research and the resulting patent portfolio for next-generation liquid crystal displays (LCDs), adaptive optics, laser-beam steering, biophotonics, and new photonic materials
  • 983
  • 28 Nov 2022
Topic Review
Glossary of Nanotechnology
This glossary of nanotechnology is a list of definitions of terms and concepts relevant to nanotechnology, its sub-disciplines, and related fields. For more inclusive glossaries concerning related fields of science and technology, see Glossary of chemistry terms, Glossary of physics, Glossary of biology, and Glossary of engineering.
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  • 02 Nov 2022
Topic Review
Vigil (Spacecraft)
Vigil, formerly known as Lagrange, is a planned solar weather mission by the European Space Agency (ESA). It envisions two spacecraft to be positioned at Lagrangian points L1 and L5. Monitoring space weather includes events such as solar flares, coronal mass ejections, geomagnetic storms, solar proton events, etc. Monitoring would help predict arrival times at the Earth and any potential effect on infrastructure. The Vigil spacecraft are anticipated to launch in the mid 2020s. On 17 May 2021, ESA began soliciting design concept studies from various European industrial and scientific consortiums for the mission. A final design will be selected after approximately 18 months, in late 2022. Simultaneously, the ESA announced the No-Name Mission contest to replace the placeholder Lagrange name. The winning name, Vigil, was announced on 10 February 2022.
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  • 10 Oct 2022
Topic Review
Charles Hard Townes Medal
The Charles Hard Townes Medal of The Optical Society is a prize for Quantum Electronics — that is to say, the physics of lasers. Awarded annually since 1981, it is named after the Nobel Prize-winning laser pioneer Charles H. Townes. Former winners include Nobel Prize laureates John L. Hall, Claude Cohen-Tannoudji, Serge Haroche, Arthur Ashkin, and Gérard Mourou.
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  • 25 Oct 2022
Biography
Fred Adams
Fred C. Adams (born 1961) is an American astrophysicist who has made contributions to the study of physical cosmology. Fred Adams is professor of physics at the University of Michigan, where his main field of research is astrophysics theory focusing on star formation, background radiation fields, and the early universe. He was educated at Iowa State University, where he earned his B.S. in 19
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  • 27 Dec 2022
Topic Review
Reference Point Indentation
Reference Point Indentation (RPI) refers to a specialized form of indentation testing. RPI utilizes a unique method of measurement by establishing a relative reference point at the location of measurement. This unique capability makes it possible to measure materials that are in motion, oddly shaped, visco-elastic, or that may be coated or covered by another, softer material. Unlike traditional indentation testing, RPI testing uses the location of measurement as the relative displacement reference position. Indentation itself is perhaps the most commonly applied means of testing the mechanical properties of materials. The technique has its origins in the Mohs scale of mineral hardness, in which materials are ranked according to what they can scratch and are, in turn, scratched by. The characterization of solids in this way takes place on an essentially discrete scale, so much effort has been expended in order to develop techniques for evaluating material hardness over a continuous range. Hence, the adoption of the Meyer, Knoop, Brinell, Rockwell, and Vickers hardness tests. More recently (ca. 1975), nanoindentation techniques have been established as the primary tool for investigating the hardness of small volumes of material. However, even more recently (ca. 2006), interest in measuring functional roles of biomaterials drove the development of the Reference Point Indentation technique. New research in field such as biomaterials has led scientists to begin considering materials as complex systems that behave differently than the constituent parts. For example, materials like bone are hierarchical and made of many components including calcium, collagen, water, and non-collagenous proteins. Each of these components has unique material properties. When combined to form bone, the function of the tissue is different than any one constituent. Understanding this mechanical system is becoming a new field of research called Materiomics. RPI specifically aims to aid materiomics researchers understand the functional capabilities of these types of materials at a relevant length-scale.
  • 959
  • 01 Nov 2022
Topic Review
Lattice Model
In physics, a lattice model is a physical model that is defined on a lattice, as opposed to the continuum of space or spacetime. Lattice models originally occurred in the context of condensed matter physics, where the atoms of a crystal automatically form a lattice. Currently, lattice models are quite popular in theoretical physics, for many reasons. Some models are exactly solvable, and thus offer insight into physics beyond what can be learned from perturbation theory. Lattice models are also ideal for study by the methods of computational physics, as the discretization of any continuum model automatically turns it into a lattice model. The exact solution to many of these models (when they are solvable) includes the presence of solitons. Techniques for solving these include the inverse scattering transform and the method of Lax pairs, the Yang–Baxter equation and quantum groups. The solution of these models has given insights into the nature of phase transitions, magnetization and scaling behaviour, as well as insights into the nature of quantum field theory. Physical lattice models frequently occur as an approximation to a continuum theory, either to give an ultraviolet cutoff to the theory to prevent divergences or to perform numerical computations. An example of a continuum theory that is widely studied by lattice models is the QCD lattice model, a discretization of quantum chromodynamics. However, digital physics considers nature fundamentally discrete at the Planck scale, which imposes upper limit to the density of information, aka Holographic principle. More generally, lattice gauge theory and lattice field theory are areas of study. Lattice models are also used to simulate the structure and dynamics of polymers.
  • 950
  • 19 Oct 2022
Biography
Norman Rasmussen
Norman C. Rasmussen (November 12, 1927 – July 18, 2003) was an American physicist.[1] Rasmussen was born in Harrisburg, Pennsylvania. He grew up on a dairy farm as the fifth of six brothers. He attended public school in Hershey, Pennsylvania. His father died when he was in eighth grade, and his family moved to Gettysburg, where his grandparents helped to care for the family. Rasmussen gradu
  • 949
  • 22 Nov 2022
Biography
Kam-Biu Luk
Kam-Biu Luk (Chinese: 陸錦標, born 1953) is a professor of physics, with a focus on particle physics, at UC Berkeley and a senior faculty member in the Lawrence Berkeley National Laboratory's physics division.[1] Luk has conducted research on neutrino oscillation and CP violation. Luk and his collaborator Yifang Wang were awarded the 2014 Panofsky Prize “for their leadership of the Daya Bay
  • 949
  • 23 Nov 2022
Biography
Peter Clive Thonemann
Peter Clive Thonemann (3 June 1917 – 10 February 2018) was an Australian-born British physicist who was a pioneer in the field of fusion power while working in the United Kingdom . Thonemann was born in Melbourne and moved to Oxford University in 1944, becoming one of the earliest researchers on the topic of controlled fusion. He led the fusion research at Oxford in its early years, before mo
  • 940
  • 27 Dec 2022
Topic Review
Mathematical and Logical Realism
According to Balaguer, only two views of the metaphysics of mathematics manage to adequately answer all objections: these are Platonic set theory (as a form of realism) and fictionalism (as a form of anti-realism). Balaguer takes a relatively reserved stance towards the dilemma that one of these two perspectives is correct through three epistemic conclusions: (a) there is no reason to believe or not believe in abstract mathematical objects, (b) it can never in principle have a reason to believe or not believe in abstract mathematical objects, or (c) there is no material fact that could determine between Platonic set theory and fictionalism, although both adequately answer all objections (except, in a way, the question of proving the existence of abstract mathematical objects). The first key question that divides the metaphysics of mathematics into two domains, is the question of whether mathematical theories represent truthful descriptions of some real part of the world. Realistic theories answer affirmatively, while anti-realistic theories answer negatively, claiming that mathematics has no ontology, or that its concepts are objectively empty. The question further divides the realist camp into two groups and is “are mathematical objects spatiotemporal?”. Platonic set theory answers negatively, while anti-Platonism answers affirmatively. The question further divides anti-Platonism into psychologism and physicalism and reads: “what is the nature of mathematical spatiotemporal objects?”. According to psychologism, the objects in question are mental objects, or mathematical statements represent truthful descriptions of mental objects, while according to physicalism, the subject of mathematical statements is non-mental parts of physical reality.
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  • 17 Nov 2023
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