Medieval and Talmudic sources explore the cosmological possibility of life beyond Earth, from rabbinic descriptions of multiple worlds and heavenly realms to medieval philosophers' discussions of whether divine revelation and Torah apply to beings on other worlds. Hasidic mysticism further develops the concept of a vast, spiritually populated multiverse.
וְשָׁט בִּשְׁמוֹנָה עָשָׂר אֶלֶף עוֹלָמוֹת
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Genesis 1:1
The opening verse 'In the beginning God created the heavens and the earth' raises the question of what else may have been created in the vast heavens, prompting later thinkers to speculate about other inhabited realms in the cosmos.
בְּרֵאשִׁ֖ית בָּרָ֣א אֱלֹהִ֑ים אֵ֥ת הַשָּׁמַ֖יִם וְאֵ֥ת הָאָֽרֶץ׃
When God began to create heaven and earth—
Psalms 115:16
The verse states 'The heavens are the heavens of God, but the earth He gave to the children of men' — a foundational text for debates about whether other worlds could be inhabited, with commentators exploring whether humanity's dominion is limited to Earth alone.
הַשָּׁמַ֣יִם שָׁ֭מַיִם לַיהֹוָ֑ה וְ֝הָאָ֗רֶץ נָתַ֥ן לִבְנֵי־אָדָֽם׃
The heavens belong to GOD, but the earth was given over to humankind.
Avodah Zarah 3b
The Talmud discusses God traveling through '18,000 worlds' (אלפי עולמות), implying a vast cosmological system beyond our own and prompting later authorities to discuss whether those worlds have inhabitants.
וּבְלֵילְיָא מַאי עָבֵיד? אִיבָּעֵית אֵימָא: מֵעֵין יְמָמָא, וְאִיבָּעֵית אֵימָא: רוֹכֵב עַל כְּרוּב קַל שֶׁלּוֹ וְשָׁט בִּשְׁמוֹנָה עָשָׂר אֶלֶף עוֹלָמוֹת, שֶׁנֶּאֱמַר: ״רֶכֶב אֱלֹהִים רִבֹּתַיִם אַלְפֵי שִׁנְאָן״, אַל תִּקְרֵי ״שִׁנְאָן״ אֶלָּא ״שֶׁאֵינָן״, וְאִיבָּעֵית אֵימָא: יוֹשֵׁב וְשׁוֹמֵעַ שִׁירָה מִפִּי חַיּוֹת, שֶׁנֶּאֱמַר: ״יוֹמָם יְצַוֶּה ה׳ חַסְדּוֹ וּבַלַּיְלָה שִׁירֹה עִמִּי״.
The Gemara asks: And during the twelve hours of the night, what does God do? The Gemara answers: If you wish, say that the night is similar to the day, i.e., God performs the same activities as in the day. And if you wish, say instead that He rides on his light cherub and flies in eighteen thousand worlds, as it is stated: “The chariots of God are twenty thousand, even [shinan] thousands” (Psalms 68:18). Do not read it as even [shinan], rather read it as: That which are not [she’einan]. Since the minimum of thousands is two thousand, the phrase: That which are not thousands, indicates that two thousand are not present, i.e., the chariots of God are twenty thousand minus two thousand, which means that God rides in eighteen thousand worlds. And if you wish, say instead that God sits and listens to the songs from the mouths of the angelic creatures, as it is stated: “By day the Lord will command His loving-kindness, and in the night His song shall be with me” (Psalms 42:9).
Chagigah 15a
The tractate discusses the heavenly realms, the angelic beings (מלאכים) in the upper worlds, and multiple heavenly 'firmaments,' providing a rabbinic framework for understanding non-human intelligent beings in other cosmic realms.
תָּנוּ רַבָּנַן: מַעֲשֶׂה בְּרַבִּי יְהוֹשֻׁעַ בֶּן חֲנַנְיָה שֶׁהָיָה עוֹמֵד עַל גַּב מַעֲלָה בְּהַר הַבַּיִת, וְרָאָהוּ בֶּן זוֹמָא וְלֹא עָמַד מִלְּפָנָיו. אָמַר לוֹ: מֵאַיִן וּלְאַיִן בֶּן זוֹמָא? אָמַר לוֹ: צוֹפֶה הָיִיתִי בֵּין מַיִם הָעֶלְיוֹנִים לְמַיִם הַתַּחְתּוֹנִים, וְאֵין בֵּין זֶה לָזֶה אֶלָּא שָׁלֹשׁ אֶצְבָּעוֹת בִּלְבַד, שֶׁנֶּאֱמַר: ״וְרוּחַ אֱלֹהִים מְרַחֶפֶת עַל פְּנֵי הַמָּיִם״ — כְּיוֹנָה שֶׁמְּרַחֶפֶת עַל בָּנֶיהָ וְאֵינָהּ נוֹגַעַת. אָמַר לָהֶן רַבִּי יְהוֹשֻׁעַ לְתַלְמִידָיו: עֲדַיִין בֶּן זוֹמָא מִבַּחוּץ. אַחֵר קִיצֵּץ בִּנְטִיעוֹת, עָלָיו הַכָּתוּב אוֹמֵר: ״אַל תִּתֵּן אֶת פִּיךָ לַחֲטִיא אֶת בְּשָׂרֶךָ״. מַאי הִיא? חֲזָא מֶיטַטְרוֹן דְּאִתְיְהִבָא לֵיהּ רְשׁוּתָא לְמֵיתַב לְמִיכְתַּב זַכְווֹתָא דְיִשְׂרָאֵל, אֲמַר: גְּמִירִי דִּלְמַעְלָה לָא הָוֵי לֹא יְשִׁיבָה וְלֹא תַּחֲרוּת, וְלֹא עוֹרֶף וְלֹא עִיפּוּי. שֶׁמָּא, חַס וְשָׁלוֹם, שְׁתֵּי רְשׁוּיוֹת הֵן.
With regard to the fate of ben Zoma, the Sages taught: There was once an incident with regard to Rabbi Yehoshua ben Ḥananya, who was standing on a step on the Temple Mount, and ben Zoma saw him and did not stand before him to honor him, as he was deep in thought. Rabbi Yehoshua said to him: From where do you come and where are you going, ben Zoma, i.e., what is on your mind? He said to him: In my thoughts I was looking upon the act of Creation, at the gap between the upper waters and the lower waters, as there is only the breadth of a mere three fingers between them, as it is stated: “And the spirit of God hovered over the face of the waters” (Genesis 1:2), like a dove hovering over its young without touching them. Rabbi Yehoshua said to his students who had overheard this exchange: Ben Zoma is still outside; he has not yet achieved full understanding of these matters. § The Gemara stated earlier that Aḥer chopped down the saplings, becoming a heretic. With regard to him, the verse states: “Do not let your mouth bring your flesh into guilt” (Ecclesiastes 5:5). The Gemara poses a question: What was it that led him to heresy? He saw the angel Mitatron, who was granted permission to sit and write the merits of Israel. He said: There is a tradition that in the world above there is no sitting; no competition; no turning one’s back before Him, i.e., all face the Divine Presence; and no lethargy. Seeing that someone other than God was seated above, he said: Perhaps, the Gemara here interjects, Heaven forbid, there are two authorities, and there is another source of power in control of the world in addition to God. Such thoughts led Aḥer to heresy.
Sanhedrin 97b
A Talmudic aggadah states that God created worlds and destroyed them before creating this world — suggesting a cosmological plurality of worlds and raising questions about inhabitants of those prior realms.
שְׁלַח לֵיהּ רַב חָנָן בַּר תַּחְלִיפָא לְרַב יוֹסֵף: מָצָאתִי אָדָם אֶחָד וּבְיָדוֹ מְגִילָּה אַחַת כְּתוּבָה אַשּׁוּרִית וּלְשׁוֹן קֹדֶשׁ. אָמַרְתִּי לוֹ: זוֹ מִנַּיִין לָךְ? אָמַר לִי: לַחֲיָילוֹת שֶׁל רוֹמִי נִשְׂכַּרְתִּי וּבֵין גִּינְזֵי רוֹמִי מְצָאתִיהָ. וְכָתוּב בָּהּ: לְאַחַר אַרְבַּעַת אֲלָפִים וּמָאתַיִם וְתִשְׁעִים וְאֶחָד שָׁנָה לִבְרִיאָתוֹ שֶׁל עוֹלָם, הָעוֹלָם יִתּוֹם. מֵהֶן מִלְחֲמוֹת תַּנִּינִים, מֵהֶן מִלְחָמוֹת גּוֹג וּמָגוֹג, וּשְׁאָר יְמוֹת הַמָּשִׁיחַ. וְאֵין הַקָּדוֹשׁ בָּרוּךְ הוּא מְחַדֵּשׁ אֶת עוֹלָמוֹ אֶלָּא לְאַחַר שִׁבְעַת אֲלָפִים שָׁנָה. רַב אַחָא בְּרֵיהּ דְּרָבָא אָמַר: לְאַחַר חֲמֵשֶׁת אֲלָפִים שָׁנָה אִיתְּמַר.
Rav Ḥanan bar Taḥlifa sent a message to Rav Yosef: I found one man, and in his hand there was one scroll written in Ashurit script and in the sacred tongue, Hebrew. I said to him: From where did this scroll come into your possession? He said to me: I was hired to serve in the Roman army and I found the scroll among the Roman archives. It was clear that the scroll was written by Jews, not Romans. And it is written in the scroll: After 4,291 years have elapsed from the creation of the world, the world will end; during those years there will be the wars of the sea monsters between the leviathan and the animals, and among those years there will be the wars of Gog and Magog and the remaining years of the messianic period. Then the world will be destroyed. And the Holy One, Blessed be He, will renew His world only after the passage of seven thousand years. Rav Aḥa, son of Rava, says that it was stated: After the passage of five thousand years.
Sefer HaIkkarim, Maamar 1 4:2
Rabbi Yosef Albo explicitly discusses the possibility of life on other worlds and the question of whether Torah could apply to such beings, concluding that our world is uniquely chosen for divine revelation.
ואולם אם אפשר להמצא תורה אלהית יותר מאחת בזמן אחד או בזמנים מתחלפים עוד יתבאר במה שיבא בעזר הצור.
The question whether there can be more than one divine law at the same time or at different times, will be discussed later with the help of God.
Kuzari 1:67
Rabbi Yehuda HaLevi discusses the uniqueness of the Earth and humanity within the created order, raising questions about whether spiritual and physical life could exist elsewhere in the cosmos.
חִבְּרוּם יְחִידִים מִבְּנֵי אָדָם, נִפְתֶּה בָהֶם מִי שֶׁדַּעְתּוֹ קַלָּה, כִּקְצָת סִפְרֵי הַחוֹבְרִים שֶׁכּוֹתְבִים בָּהֶם מִנְיָנֵי עֲשָׂרוֹת אַלְפֵי שָׁנִים, אוֹ כְמוֹ סֵפֶר הָעֲבוֹדָה הַנְּבָטִית שֶׁזּוֹכְרִים שָׁם שֵׁמוֹת יַנְבּוּשָׁר וְצַגְרִית וְדוּאַנִי, וְאָמְרוּ כִּי הֵם הָיוּ קֹדֶם אָדָם, וְשֶׁיַּנְבּוּשָׁר הָיָה רַבּוֹ שֶׁל אָדָם הָרִאשׁוֹן, וְהַדּוֹמֶה לָזֶה.
It is believed that they lived before Adam, who was the disciple of Janbūshār, and such like.
Guide for the Perplexed, Part 1
Rambam discusses the spheres of the heavens and their intellects (separate intellects), presenting a cosmos populated by non-human rational beings — the celestial intelligences — which some later thinkers compared to the idea of extraterrestrial life.
ואין זה אלא כאמירתו של מי שאמר: בן אדם חטא והפליג ברשע, ועל כן הפך לכוכב בשמים. זו היתה כוונת הקושיה ומשמעותה, אף שלא נוסחה בלשון זה.
As man’s distinction consists in a property which no other creature on earth possesses, viz., intellectual perception, in the exercise of which he does not employ his senses, nor move his hand or his foot, this perception has been compared—though only apparently, not in truth—to the Divine perception, which requires no corporeal organ. On this account, i.e., on account of the Divine intellect with which man has been endowed, he is said to have been made in the form and likeness of the Almighty, but far from it be the notion that the Supreme Being is corporeal, having a material form.
Nefesh HaChayim, Gate I 1:1
Rav Chaim of Volozhin describes a vast cosmic structure of innumerable worlds (עולמות) all sustained and affected by human action, implying a universe of extraordinary complexity and scope far beyond our visible world.
כתיב ויברא אלקים את האדם בצלמו בצלם אלקים ברא אותו וכן כתיב כי בצלם אלקים עשה את האדם.
It is written (Bereshit 1:27): “God-Elohi”m [thus] created man with His tzellem; with the tzellem of God-Elohi”m, He created him.” And it is also written (Bereshit 9:6): “... for with the tzellem of God-Elohi”m He made man.”
Derekh Hashem, Part Two, On Divine Providence in General.1
The Ramchal discusses the structure of creation and the unique role of humanity as the central purpose of the cosmos, with all other created beings — celestial and terrestrial — oriented around mankind's spiritual mission.
ידוע ומבואר הוא שכל הנבראים כלם שנבראו בין העליונים ובין התחתונים הנה נבראו לפי שראתה בהם החכמה העליונה צורך ותועלת למה שהוא התכלית הכללי של הבריאה. וכל חוקותיהם ומשפטיהם הטבעיים הוחקו והוטבעו כפי מה שגזרה החכמה העליונה היותו נאות לפי הכוונה שכיונה בנברא ההוא. ואולם מאותו הטעם עצמו שנבראו ראוי ג״כ שיתקיימו כל זמן היות בם תועלת לכלל הבריאה כמ״ש וע״כ האדון ב״ה שברא כל הנבראים האלה לא ימנע ג״כ מלהשגיח עליהם לקיימם בואתו המצב שהוא רוצה אותם בו:
It is well-known and clear that all of the creatures that were created - both the higher ones and the lower ones - were surely created because the Supreme Wisdom saw a need and a function for them for the general purpose of the world. And all of their natural axioms and properties were set and embedded, according to what the Supreme Wisdom decreed to be appropriate, according to the intention that It intended for that creature. However for that very reason itself that they were created, it is also fit that they by preserved the whole time that they have that function for the general creation, as I have written. And therefore the Master, blessed be He, that created all of these creatures will also not stop from supervising over them, to preserve them in the state that He wants them to be.
Maggid Devarav leYaakov 1
The Maggid of Mezeritch teaches about the Ein Sof filling all worlds (ממלא כל עלמין) and the existence of countless spiritual and physical worlds — a Hasidic framework that implicitly embraces a vast, populated multiverse.
או יאמר מגורי אביו דכל מחשבה הוא עולם שלם והם ניצוצות הקדושה ואסף אותן אל השורש.
When he merits, he is granted a soul from the world of the Throne, meaning that through his thoughts and intentions, he creates a throne for the Holy One, blessed be He.