In the classical case, the invariance, or symmetry, group and the covariance group coincide, but, interestingly enough, they part ways in relativistic physics. The symmetry group of the general theory of relativity includes all differentiable transformations, i.e., all properties of an object are dynamical, in other words there are no absolute objects. The formulations of the general theory of relativity, unlike those of classical mechanics, do not share a standard, i.e., there is no single formulation paired with transformations. As such the covariance group of the general theory of relativity is just the covariance group of every theory.
The symmetry group of the general theory of relativity includes what?
all differentiable transformations

Electrical recording preceded electrical home reproduction because of the initial high cost of the new system. In 1925, the Victor company introduced the Victor Orthophonic Victrola, an acoustical record player that was specifically designed to play electrically recorded discs, as part of a line that also included electrically reproducing Electrolas. The acoustical Orthophonics ranged in price from US$95 to US$300, depending on cabinetry; by comparison, the cheapest Electrola cost US$650, the price of a new Ford automobile in an era when clerical jobs paid about $20 a week.
What was the initial cost range of early recording devices?
US$95 to US$300

Charles Darwin's grandfather Erasmus Darwin outlined a hypothesis of transmutation of species in the 1790s, and Jean-Baptiste Lamarck published a more developed theory in 1809. Both envisaged that spontaneous generation produced simple forms of life that progressively developed greater complexity, adapting to the environment by inheriting changes in adults caused by use or disuse. This process was later called Lamarckism. Lamarck thought there was an inherent progressive tendency driving organisms continuously towards greater complexity, in parallel but separate lineages with no extinction. Geoffroy contended that embryonic development recapitulated transformations of organisms in past eras when the environment acted on embryos, and that animal structures were determined by a constant plan as demonstrated by homologies. Georges Cuvier strongly disputed such ideas, holding that unrelated, fixed species showed similarities that reflected a design for functional needs. His palæontological work in the 1790s had established the reality of extinction, which he explained by local catastrophes, followed by repopulation of the affected areas by other species.
Whose paleontology work in the 1790s established the reality of extinction?
Georges Cuvier