They are so fools that some rascal will take some machine and go there? That is not possible. So we have to prepare.
So Kṛṣṇa says, yānti deva-vratā devān: (BG 9.25) "If you want to go to the heavenly planets you can go. You prepare yourself." Pitṟn yānti: "Pitṛloka you can go." Mad-yājino 'pi yānti mām: "But if you prepare yourself for coming to Me, back to home, back..., you can do so." So if we have to prepare ourself to go to other, higher planetary system...
And here within this material world, within this universe, ābrahma-bhuvanāl lokāḥ punar āvartino 'rjuna (BG 8.16). Even if you go to the highest planetary system, Brahmaloka. The Brahmaloka means you cannot calculate one day's life. That is stated in the Bhagavad-gītā. Sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ (BG 8.17). Sahasra-yuga. One yuga means forty-three lakhs of years, and multiplied by one thousand, such year, is only twelve hours of Brahmaloka life. Similarly, twenty-four hours, one month, one year... So it is very, very long duration of life there, where Brahmā lives.