The nature of the material world is destructive. According to the Bhagavad-gītā, there is some partial truth to the assumption of the physical scientist that there is annihilation of the material and anti-material worlds when they chance to clash. The material world is a creation of changing modes of nature. These modes (guṇas) are known as sattva (goodness), rajas (passion) and tamas (ignorance). The material world is created by the mode of rajas, maintained by the mode of sattva, and annihilated by the mode of tamas. These modes are omnipresent in the material world, and as such, at every hour, every minute, every second, the process of creation, maintenance and annihilation is taking place all over the material universe. The highest planet of the material universe, Brahmaloka, is also subjected to these modes of nature, although the duration of life on that planet, due to the predominance of the mode of sattva, is said to be 4,300,000 x 1,000 x 2 x 30 x 12 x 100 solar years. Despite this long duration, however, Brahmaloka is subject to destruction. Although life on Brahmaloka is fantastically long compared to life on Earth, it is only a flash in comparison to the eternal life of the nonmaterial worlds. Consequently, the speaker of the Bhagavad-gītā, Lord Śrī Kṛṣṇa, asserts the importance of the anti-material universe, which is His abode.
Lord Kṛṣṇa instructs that all the planets within the material universe are destroyed at the end of 4,300,000 x 1,000 x 2 x 30 x 12 x 100 solar years. And all the living beings inhabiting these material planets are destroyed materially along with the destruction of the material worlds. The living entity, however, is constitutionally an anti-material particle. But unless he elevates himself to the region of the anti-material worlds by cultivation of anti-material activities, he is destroyed materially at the annihilation of the material worlds and is subject to take rebirth in a material shape with the rebirth of a new material universe. In other words, he is subject to the pains of repeated birth and death. Only those living entities who take to the loving service of the Personality of Godhead during the manifested stage of material life are undoubtedly transferred to the anti-material worlds after quitting the material body. Immortality is obtained only by those who return to Godhead by practice of anti-material activities.
What are these anti-material activities? They are medicines. For example, when a man falls ill, he goes to a physician who prescribes medicines which eventually cure the suffering patient. Similarly, the materialist is ailing, and he should consult an expert transcendentalist-physician. What is his ailment? He is suffering the tribulations of repeated births, deaths, diseases and old age. Once he agrees to put himself under the "back to Godhead" treatment, he is able to transfer himself to the anti-material world, where there is eternal life instead of birth and death.