Q&A: Physics
Physics
Question
Hello Honored Rabbi,
I very much enjoy reading and commenting on the site. Thank you very much.
I was wondering whether the Rabbi could briefly explain to me the object “time.” I heard that it is a dimension. What does that mean? Is it a “thing”? For example, can one make a vow by attaching it to time?
More power to you.
Answer
This could be discussed at great length. In general, the philosophers disagreed over whether time exists in some sense (although of course it is clear that it has no mass or location), or whether it is a way in which we view reality (time is not a thing, but rather a cognitive/conceptual framework through which we perceive reality—as Kant, for example, held). I once wrote (following McTaggart) that there are two kinds of time axes: one objective and the other subjective. Therefore one can speak about the flow of time, even though when something flows, this happens along the time axis (see Column 33).
In Jewish law, it seems that time is treated as an existing entity. That emerges from several places, for example from what you mentioned—that one can anchor a vow to a day (a unit of time). See the discussion in Shevuot 20 and Nedarim 12 (“like the day on which Gedaliah son of Ahikam was killed”). But in the philosophical writings of the medieval authorities (Rishonim), one can find both conceptions. There are two articles by Rabbi Kasher on the nature of time in Jewish law and in general, and likewise in Measures for the Study of Jewish Law and elsewhere.
The question of whether it is a dimension or not is connected to the theory of relativity. There, space and time are viewed as a four-dimensional coordinate system. The meaning of this is that one can “rotate” the system, and in the new system the time axis will be a combination of the time and space axes of the original system (as with rotating an ordinary coordinate system). On this matter, some have cited the Mishnah in Sefer Yetzirah (1:5):
Ten sefirot of nothingness: their measure is ten, which have no end; the depth of beginning and the depth of end, the depth of good and the depth of evil, the depth of above and the depth of below, the depth of east and the depth of west, the depth of north and the depth of south. The singular Master, God, faithful King, rules over all of them from His holy dwelling forever and ever.
However, there one does not see the significance of time being a dimension. To take time as just another coordinate without speaking about mixing time and space is merely a definition and not really a substantive claim. This is an example of what I wrote in the last column (250) about the chain-development of ideas, where people find sources for modern ideas in ancient texts, but in fact it is not really the same idea at all, just something fairly trivial.
Discussion on Answer
And a bright morning to you,
A. Why would something that has no mass and location not exist? What about a photon or a light wave? I don’t see any necessity in that. What about the Holy One, blessed be He?
B. A vow always attaches to an object; otherwise it is an oath and not a vow. Here it attaches to a day.
C. Ask them. In my view there is no difference.
D. It is not connected to relativity. That is a question in philosophy, not in science.
Welcome, wise man!
A. I am asking what kind of existence those philosophers wanted to grant to time. I wasn’t asking rhetorically. In order to argue that time has existence, one has to ascribe some type of existence to it. The Rabbi ruled out mass and location. In what way did they want to claim that it nevertheless exists? And really, what kind of existence do a photon and a light wave have? As for the Holy One, blessed be He, I would dare say that He has neither matter nor form, but only spiritual existence.
B. Rashi there explains that he is attaching it to meat. Rashi’s wording is: “Just as I prohibited meat to myself on that day,” etc.
C. Bummer.
D. So relativity does not prove it either way? In the twin paradox, for example, where the accelerating twin is younger—is that the result of something that does not exist in reality, but is caused only by a form of perception?
E. The Rabbi presented two sides: an existing thing, or a form of perception as Kant held. But according to Kant, every existing thing as grasped by us is like that, no?
A. I didn’t understand. There is existence without place and time. I don’t know what more to say about that. What else do you want me to say about it? Even existence in place and time does not tell me much about the sense of existence. Place and time are properties, not conditions for the concept of existence.
B. That does not seem to me to be the straightforward reading of the Talmud.
D. The twin is younger in the sense of biological age (how his body looks), not in the pure sense of time. We have no access to time itself, only to the expressions of processes that occur along it.
Hello hello and good morning!
A. The Rabbi brought the philosophers’ inquiry whether time is something that exists or not, but even if time exists, it still has no mass or location. So in what sense does time exist?
B. In Jewish law, the Rabbi wrote that time is seen as an existing thing, and the Rabbi brought as proof the case of one who vows “like the day on which Gedaliah son of Ahikam died.” If I understood correctly, the Talmud there is speaking about someone who attaches his vow to another vow. In such a case, he is attaching it to a vow. But not to the actual time of that day; rather to the vow-prohibition that took effect on certain objects on a certain day. What I wanted to ask is whether a person can impose a vow-prohibition (which, as is known, is not on the person) not on a particular object, but rather prohibit a certain time—so that the time is forbidden to him. In what way? By deriving benefit from the time.
C. I remember a certain rabbi, the son-in-law of one of today’s great heads of yeshivot, whom I asked why people say so simply that the prohibition of eating on Yom Kippur is on the person. Why not say it’s on the object! (I hope I didn’t mix up the categories.) So even though the whole discussion is in the conceptual lomdus categories of object-based and person-based prohibition, he answered me: “Don’t ask me philosophical questions”…. What parameters would the Rabbi assign to lomdus, and what to philosophy, the way this is perceived in the Haredi world?
D. According to relativity, is time something real, or a form of perception?
Much appreciated!