The Torah teaches that the entire universe was created for man. The Talmud states that there are around a quintillion (10¹⁸) stars and that all were created for man’s sake. It even says that angels and spiritual worlds exist for this purpose. This raises a question: How can man, living on Earth, be the center of the universe?
Our Sages understood the vastness of the cosmos and knew many stars were far larger than Earth. However, size and number are insignificant to an infinite God. The human brain is more complex than galaxies, and man’s Divine soul surpasses even the highest angels. A vast universe for man is logical, but its necessity still needs explanation. Some say that contemplating the universe helps us grasp God's greatness and develop a deeper reverence for Him. But when considering extraterrestrial life, the question becomes more complex.
Rabbi Chasdai Crescas was among the first to discuss extraterrestrial life, concluding that Jewish theology does not rule out its existence. He cited the Talmud, which speaks of God flying through 18,000 worlds, suggesting they require His providence and may be inhabited. However, this could refer to spiritual worlds rather than physical ones.
Rabbi Yosef Albo, in contrast, argued that since the universe was created for man, no other beings with free will can exist. If extraterrestrial life lacks free will and does not serve man (as animals and plants do), it would have no purpose and be superfluous. Some support this view with the Talmudic teaching that places not destined for human habitation were never inhabited—though this may refer only to Earth.
The Sefer HaBris presents a middle view: extraterrestrial life exists but lacks free will, which is unique to man. According to this opinion, the 18,000 worlds are physical and inhabited. As proof, he cites Judges 5:23, "Cursed is Meroz… cursed are its inhabitants," and the Talmudic opinion that Meroz is a star—implying the existence of life beyond Earth.
Even this proof is debated. The Zohar also calls Meroz a star but suggests its “inhabitants” refer to celestial camps, possibly planets. Still, the simple reading of the verse supports the Sefer HaBris. He also argues that extraterrestrial beings, like sea creatures compared to land creatures, may be vastly different from earthly life. While they may have intelligence, they lack free will—reserved for humans, who received the Torah.
A question arises: If extraterrestrial beings lack free will, why were Meroz’s inhabitants cursed? The answer is that even angels, despite lacking free will, can be punished. The great Kabbalist Rabbi Moshe Cordovero supports the idea that only one species—man—possesses free will. Since God’s unity allows only one system of spiritual worlds, there cannot be another species with free will.
The Zohar strongly supports the existence of extraterrestrial life. The Midrash speaks of seven earths, which Ibn Ezra sees as continents, but the Zohar describes them as separate, inhabited worlds. This aligns with the Sefer HaBris's claim that intelligent extraterrestrial beings exist but lack free will and moral responsibility. Free will is not observable—it is evident only because God gave man the Torah.
Yet, if extraterrestrial beings do not serve man, why do they exist? The Tikunei Zohar provides an answer. It interprets the verse (Song of Songs 6:8), "Worlds without number," as referring to stars, each considered a separate world. It explains that in the future, each Tzaddik (righteous person) will rule over a star, fulfilling the verse (Ezekiel 48:35), "Around Him are eighteen thousand." These stars may correspond to the 18,000 Tzaddikim who will be granted their own worlds.
If the stars and their planets are intended as abodes for Tzaddikim, how will they reach them? The Talmud (Isaiah 40:31) states that in the Future World, God will give Tzaddikim wings to escape Earth. The Zohar goes further, saying they will fly through the universe. This teaching anticipates space travel and suggests that it is part of the prelude to the Messianic era.