The Sun, as he travels round over the surface of the Earth, brings "noon" to all places on the successive meridians which he crosses: his journey being made in a westerly direction, places east of the Sun's position have had their noon, whilst places to the west of the Sun's position have still to get it. Therefore, if we travel easterly, we arrive at those parts of the Earth where "time" is more advanced, the watch in our pocket has to be "put on" or we may be said to "gain time." If, on the other hand, we travel westerly, we arrive at places where it is still "morning," the watch has to be "put back," and it may be said that we "lose time." But, if we travel easterly so as to cross the 180th meridian, there is a loss, there, of a day, which will neutralize the gain of a whole circumnavigation; and, if we travel westerly, and cross the same meridian, we experience the gain of a day, which will compensate for the loss during a complete circumnavigation in that direction. The fact of losing or gaining time in sailing round the world, then, instead of being evidence of the Earth's "rotundity," as it is imagined to be, is, in its practical exemplification, an everlasting proof that the Earth is not a globe.
The most commonly accepted explanation of this is that the space agencies of the world are involved in a conspiracy faking space travel and exploration. This likely began during the Cold War's 'Space Race', in which the USSR and USA were obsessed with beating each other into space to the point that each faked their accomplishments in an attempt to keep pace with the other's supposed achievements. Since the end of the Cold War, however, the conspiracy is most likely motivated by greed rather than political gains, and using only some of their funding to continue to fake space travel saves a lot of money to embezzle for themselves.