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:
“Four spectres haunt the Poor—Old Age, Accident, Sickness and Unemployment. We are going to exorcise them. We are going to drive hunger from the hearth. We mean to banish the workhouse from the horizon of every workman in the land.”
—David Lloyd George (1863–1945)
“Every reform was once a private opinion, and when it shall be a private opinion again, it will solve the problem of the age.”
—Ralph Waldo Emerson (1803–1882)