Even if a materialist wants to enjoy developed material facilities, he can transfer himself to planets where he can experience material pleasures much more advanced than those available on the earth planet. But the best plan is to prepare oneself to return to the spiritual sky after leaving the body. However, if one is intent on enjoying material facilities, one can transfer himself to other planets in the material sky by utilizing yogic powers. The playful spaceships of the astronauts are but childish entertainments and are of no use for this purpose.
The aṣṭāṅga-yoga system is also materialistic, inasmuch as it teaches one to control the movements of air within the material body. The spiritual spark, the soul, is floating on air within the body, and inhalation and exhalation are the waves of that air containing the soul. Therefore the yoga system is a materialistic art of controlling this air by transferring it from the stomach to the navel, from the chest to the collarbone and from there to the eyeballs and from there to the cerebellum and from there to any desired planet. The velocities of air and light are taken into consideration by the material scientist, but he has no information of the velocity of the mind and intelligence. We have some limited experience of the velocity of the mind, because in a moment we can transfer our minds to places hundreds of thousands of miles away. Intelligence is even finer. Finer than intelligence is the soul, which is not matter like mind and intelligence but is spirit, or antimatter. The soul is hundreds of thousands of times finer and more powerful than intelligence. We can thus only imagine the velocity of the soul in its traveling from one planet to another. Needless to say, the soul travels by its own strength and not with the help of any kind of material vehicle.
The bestial civilization of eating, sleeping, fearing and sense-gratifying has misled modern man into forgetting how powerful a soul he has. As we have already described, the soul is a spiritual spark which is many, many times more illuminating, dazzling and powerful than sun, moon or electricity. Human life is spoiled when man does not realize his real identity with his soul. Lord Caitanya appeared with His disciple Nityānanda to save man from this type of misleading civilization.
Śrīmad-Bhāgavatam also describes how yogīs can travel to all the planets in the universe. When the vital force is lifted to the cerebellum, there is every chance of this force bursting out from the eyes, nose, ears, etc., as these are places which are known as the seventh orbit of the vital force. But the yogīs can block out these holes by complete suspension of air. The yogī then concentrates the vital force in the middle position, that is, between the eyebrows. At this position, the yogī can think of the planet into which he wants to enter after leaving the body. He can then decide whether he wants to go to the abode of Kṛṣṇa in the transcendental Vaikuṇṭhas from which he will not be required to descend into the material world, or to travel to higher planets in the material universe. The perfect yogī is at liberty to do either.
For the perfect yogī who has attained success in the method of leaving his body in perfect consciousness, transferring from one planet to another is as easy as an ordinary man's walking to the grocery store. As already discussed, the material body is just a covering of the spiritual soul. Mind and intelligence are the undercoverings, and the gross body of earth, water, air, etc., is the overcoating of the soul. As such, any advanced soul who has realized himself by the yogic process, who knows the relationship between matter and spirit, can leave the gross dress of the soul in perfect order and as he desires. By the grace of God, we have complete freedom. Because the Lord is kind to us, we can live anywhere—either in the spiritual sky or in the material sky, upon whichever planet we desire. However, misuse of this freedom causes one to fall down into the material world and suffer the threefold miseries of conditioned life. The living of a miserable life in the material world by dint of the soul's choice is nicely illustrated by Milton in Paradise Lost. Similarly, by choice the soul can regain paradise and return home, back to Godhead.
At the critical time of death, one can place the vital force between the two eyebrows and decide where he wants to go. If he is reluctant to maintain any connection with the material world, he can, in less than a second, reach the transcendental Vaikuṇṭha and appear there completely in his spiritual body which will be suitable for him in the spiritual atmosphere. He has simply to desire to leave the material world in both finer and grosser forms and then move the vital force to the topmost part of the skull and leave the body from the hole in the skull called the brahma-randhra. This is the highest perfection in the practice of yoga.
Of course man is endowed with free will, and as such if he does not want to free himself of the material world he may enjoy the life of brahma-pāda (occupation of the post of Brahmā) and visit Siddhaloka, the planets of materially perfect beings who have full abilities to control gravity, space, time, etc. To visit these higher planets in the material universe, one need not give up his mind and intelligence (finer matter), but need only give up grosser matter (the material body).