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This model truncates at degree 12 (168 coefficients) with an approximate spatial resolution of 3,000 kilometers. It is the model used by the United States Department of Defense , the Ministry of Defence (United Kingdom) , the United States Federal Aviation Administration (FAA), the North Atlantic Treaty Organization (NATO), and the ...
The earliest ideas on the nature of magnetism are attributed to Thales (c. 624 BC – c. 546 BC). [1] [2] In classical antiquity, little was known about the nature of magnetism. No sources mention the two poles of a magnet or its tendency to point northward. There were two main theories about the origins of magnetism.
Walter M. Elsasser, considered a "father" of the presently accepted dynamo theory as an explanation of the Earth's magnetism, proposed that this magnetic field resulted from electric currents induced in the fluid outer core of the Earth. He revealed the history of the Earth's magnetic field through pioneering the study of the magnetic ...
Two pairs of gauge transformed potentials (φ, A) and (φ′, A′) are called gauge equivalent, and the freedom to select any pair of potentials in its gauge equivalence class is called gauge freedom. Again by the Poincaré lemma (and under its assumptions), gauge freedom is the only source of indeterminacy, so the field formulation is ...
By analogy with Earth's magnetic field, these are called the magnet's "north" and "south" poles. Before magnetism was well understood, the north-seeking pole of a magnet was defined to have the north designation, according to their use in early compasses. However, opposite poles attract, which means that as a physical magnet, the magnetic north ...
Luigi Mangione, accused in the killing of UnitedHealthcare CEO Brian Thompson, will plead not guilty, according to his lawyer, Thomas Dickey.
Poisson's electrical and magnetical investigations were generalized and extended in 1828 by George Green. Green's treatment is based on the properties of the function already used by Lagrange, Laplace, and Poisson, which represents the sum of all the electric or magnetic charges in the field, divided by their respective distances from some given point: to this function Green gave the name ...
Canadian hockey player Matthew Petgrave has begun crowdfunding to help cover his legal fees in connection with the death of fellow hockey player Adam Johnson.