The horizon problem is a problem with the standard cosmological model of the Big Bang which was identified in the 1970s. It points out that different regions of the universe have not "contacted" each other because of the great distances between them, but nevertheless they have the same temperature and other physical properties. This should not be possible, given that the transfer of information (or energy, heat, etc.) can occur, at most, at the speed of light. The horizon problem may have been answered by inflationary theory, and is one of the reasons for that theory's formation. Another proposed, though less accepted, theory is that the speed of light has changed over time, called variable speed of light.
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Famous quotes containing the words horizon and/or problem:
““Dark times” is what they call it in Norway when the sun remains below the horizon all day long: the temperature falls slowly but surely at such times.—A nice metaphor for all those thinkers for whom the sun of mankind’s future has temporarily disappeared.”
—Friedrich Nietzsche (1844–1900)
“I tell you, sir, the only safeguard of order and discipline in the modern world is a standardized worker with interchangeable parts. That would solve the entire problem of management.”
—Jean Giraudoux (1882–1944)