Someone told me that according to Judaism, human beings are the only conscious beings in the universe. Is there any basis to this?

The uniqueness of humankind is not our consciousness, but the way that consciousness is able to enter the realms of good and evil, make decisions and distinguish between them.

Third, Maimonides and others write about the heavenly bodies as conscious beings—and not simply in an allegorical sense. If anyone should ask, “How can a ball of helium and hydrogen contain consciousness?” simply ask in return, “And that a warm mass of gray meat has consciousness is reasonable?”

Second, there are plenty of accounts in the Torah of the higher angels, who are conscious of a realm of reality far beyond ours.

First of all, the sages discuss the fact that animals also feel pain, based on the biblical prohibition against causing them undue suffering.

Sources in Torah

Several Torah scholars of past generations have discussed the possibility of life on other planets. Rabbi Chasdai Crescas (Spain, 1340–1411) wrote that there is nothing anywhere in Torah that negates such a possibility. Rabbi Yosef Albo (Spain, 1380–1444), on the other hand, disagreed. Rabbi Pinchas Horowitz (Poland 1765-1861), cites Albo, but rejects his thesis.

Shortly after the first moon landing, the Rebbe, Rabbi Menachem M. Schneerson, of blessed memory, pointed out that there is support in Torah for the notion that life exists on other planets. Furthermore, we can know something about that life through deduction from what the Torah tells us. Here is his argument:

In the Book of Judges, Deborah the prophetess sings about the victory of Barak over Sisera. In her song, she says, “Cursed be Meroz! Cursed, cursed be its inhabitants, says the angel of G‑d!”

Where is Meroz, and who are its inhabitants? The Talmud gives two explanations, one of them being that Meroz is a star or planet. The heavenly bodies had also come to help the Israelites, as Deborah stated just one verse earlier, “From the heavens they fought, the stars from their orbits . . .” This star, however, which was the dominant star of Sisera, apparently did not come to their aid. And so, General Barak penalized Meroz—and its inhabitants.

Are these inhabitants intelligent? Intelligence is defined by Torah to mean the capacity to make decisions with free will. Free will is only possible where there is Torah, whereby the Creator offers His creatures more than one possibility and asks that they make the appropriate choice. (Torah includes the laws of Noah, which are given to all human beings.) In other words, just as we are created by the Creator's word, so we are provided free choice by His command to do or not do.

So, if there would be intelligent life elsewhere in the universe, those creatures would have to have Torah. Could they have a different Torah than us? This is not possible, since Torah is truth, and there cannot be two truths.

Could they then have the same Torah as us? This also seems impossible, since the Torah itself describes in detail how the Torah was revealed on this planet, and that account itself has a strong impact on how the Torah is to be fulfilled.

It therefore appears that although it is quite possible there is life on other planets, that life would not be intelligent in a way similar to human life and culture.