Context and question: Time appears to have a directionthe past lies behind, fixed and immutable, while the future lies ahead and is not necessarily fixed. Yet for the most part the laws of physics do not specify an arrow of time, and allow any process to proceed both forward and in reverse. This is generally a consequence of time being modeled by a parameter in the system being analyzed, where there is no "proper time": the direction of the arrow of time is sometimes arbitrary. Examples of this include the Second law of thermodynamics, which states that entropy must increase over time (see Entropy); the cosmological arrow of time, which points away from the Big Bang, CPT symmetry, and the radiative arrow of time, caused by light only traveling forwards in time (see light cone). In particle physics, the violation of CP symmetry implies that there should be a small counterbalancing time asymmetry to preserve CPT symmetry as stated above. The standard description of measurement in quantum mechanics is also time asymmetric (see Measurement in quantum mechanics).
In particle physics what should there be to preserve entropy?
Answer: unanswerable
Context and question: Public buildings generally varied between the extremes of plain boxes with grid windows and Italian Late Renaissance palaces, depending on budget. Somerset House in London, designed by Sir William Chambers in 1776 for government offices, was as magnificent as any country house, though never quite finished, as funds ran out. Barracks and other less prestigious buildings could be as functional as the mills and factories that were growing increasingly large by the end of the period. But as the period came to an end many commercial projects were becoming sufficiently large, and well-funded, to become "architectural in intention", rather than having their design left to the lesser class of "surveyors".
All what types of prestigious buildings worse functional as mills and factories?
Answer: unanswerable
Context and question: The Pro Electron standard, the European Electronic Component Manufacturers Association part numbering scheme, begins with two letters: the first gives the semiconductor type (A for germanium, B for silicon, and C for materials like GaAs); the second letter denotes the intended use (A for diode, C for general-purpose transistor, etc.). A 3-digit sequence number (or one letter then 2 digits, for industrial types) follows. With early devices this indicated the case type. Suffixes may be used, with a letter (e.g. "C" often means high hFE, such as in: BC549C) or other codes may follow to show gain (e.g. BC327-25) or voltage rating (e.g. BUK854-800A). The more common prefixes are:
What is the most common reason to have a suffix on a device's number?
Answer:
unanswerable