In last week’s parsha, Moshe said that he would call on the heavens and the earth to be witnesses to the brit between ה׳ and Bnei Yisrael:
And in this week’s parsha, he actually does call on them:
How can the heavens and the earth be “witnesses”? Rashi gives two reasons in this week’s parsha:
Now, those are two requirements for being good witnesses: they have to be available to testify (עֵדִים שֶׁהֵן קַיָּמִים לְעוֹלָם), and the witnesses have to inflict the punishment:
But that doesn’t answer the question. How can the heavens and the earth, inanimate objects, testify that ה׳ made a covenant with Bnei Yisrael?
Rashi gives a another answer in last week’s parsha:
The fact that the heavens and the earth—the created universe—obey the laws of physics is in fact testimony, proof, that ה׳ made a covenant with us. The entire purpose of creation was the brit of the Torah.
Babies love dropping things from their high chairs, over and over again, because it is so fun that gravity works, every single time. We are old enough to take those things for granted. But we need to be able to look at the fact that the laws of physics—חֻקּוֹת שָׁמַיִם וָאָרֶץ—work consistently, and learn from that that ה׳'s covenant with us still applies, and we have to do our jobs in keeping the universe running.