There's no way you can visit every world in No Man's Sky.
Sean Murray, co-founder of developing studio Hello Games, told IGN that the procedurally generated universe in No Man's Sky, the indie space exploration game that has captivated gamers since it was revealed in December, creates worlds on the scale of two to the power of 64.
In numerical terms, that's 18.4 quintillion planets, or 18,446,744,073,709,551,616 if you want to see all of the digits. Visiting that many planets in the game at the rate of 1 per second would take about, oh, 584 million years.
No Man's Sky has touted its universe as functionally infinite, which know-it-alls on message boards tut-tutted is impossible, of course, as all technology has a limitation. So, Murray told IGN, Hello Games plotted out its universe on a scale of 2 to the power of 64 to be sure it was totally out of reach for a person or a team of persons ever to see all of No Man's Sky's universe.
Because 2 to the power of 32 — the original number of planets the game would have generated — would create some 4.29 billion worlds. Realize that 80 years — the average life expectancy in the U.S. — comprises 2.5 billion seconds and change.
It would take about 7.3 billion persons, all working from birth until death, visiting a planet every second of their lives in this game, to see 18.4 quintillion worlds combined. The current population of Earth is 8 billion people. So, yeah, No Man's Sky has an infinite universe, to any reasonable person, anyway.
For more on No Man's Sky, see Polygon's E3 preview.