(My previous post was about the emotional components of loving G-d. This post, from Chabad.org, is a modern statement of loving G-d from the traditional ChaBaD approach: Developing a love for G-d based on internalizing intellectual ideas and concepts. It’s longer than my usual posts, even when borrowed, but it’s well worth reading.)
Everything is forever running and returning
Rabbi Tzvi Freeman 
What do string theory and Hebrew letters have in common?
No one has ever seen a string, and no one has yet come up with a practical experiment to demonstrate that string theory is true. Despite all that, I still find it an attractive idea. For two reasons: Because it attempts to explain the fundamental fabric of the universe in a single, consistent way. And because that way is so strikingly similar to the explanation Kabbalists have held for centuries.
String theory says the universe is made of multiple kinds of vibrations. The vibrations are called “strings,” because they are one-dimensional. My guitar also has strings, not perfectly one-dimensional, but they also vibrate. The vibration of my guitar strings generates sound — hopefully, nice sounds. The vibrations of the strings we’re talking about here generate matter.
How does that work? Well, string theory posits that vibration translates into energy — the higher the frequency, the greater the energy. Energy, Einstein has already explained, translates into matter — as in e=mc2. So, using the speed of light as the exchange rate, these vibrations generate particles of matter.
It’s strange to think of matter as a tune being played by a string.
We intuitively think of matter as something very static, just sitting there. It’s strange to think of matter as a tune being played by a string. But that’s what we’re saying here. According to the tune a string plays, so will be the properties of the particle it generates. There are many properties to a particle, and string theory tries to deal with all of them, partly by vibrating these strings through multiple dimensions and describing them as closed or open. But the principal property of the string is its vibration frequency.
A string playing at one frequency gets you an electron. At another, it gets you the tiny quarks that make up a neutron. Yet another gets you the quarks you need for a proton. And so on, until the whole range of 35 or so particles, along with their 19 different constants, all follow from the single concept of a vibrating string. In essence, a very simple idea. (In application, researchers have found, it becomes almost impossibly complex; but hey, that’s not our problem.)
So now we can define the multitude of different particles in terms of something else — strings. But what are strings? A physicist will just tell you that they are “fundamental.” That means something from which everything else is made. “Fundamental” means it just has to be there, so it is. Which doesn’t tell us much.
Basically, the only meaningful way we can talk about these strings is in terms of their vibrations. No vibrations means no energy, no mass — and so, obviously, no string. No strings means no particles. No particles, no universe. And so, all of the matter and energy in the universe is defined in relation to fundamental objects that lack any further meaning. Other than vibrating.
As I mentioned, these one-dimensional strings are said to be vibrating within multiple dimensions — at last count, eleven of them. We can’t see those dimensions (they folded up and got real small, if you can imagine that). But the math works (mostly). Add the weirdness of super-symmetry to the mix, and string theory is begging many metaphysical questions about the nature of our reality and why we perceive it the way we do.
While they’re out there groping for the meta behind the physics, I just want to suggest picking a few of the offerings of a metaphysical tree that’s been around a long time, and also explains a lot. That’s the Tree of Life, a.k.a. Kabbalah.
Running and Returning
To the Kabbalist, the fundamental fabric of the cosmos is not strings, but otiyot (letters). The sound of each of the otiyot, as well as their two-dimensional form on parchment or paper, are analogs for the varied articulations of creative energy that generate our material world. And that energy is in a state of perpetual oscillation, called ratzo v’shov, “running and returning.” It is running back to its origin in an act of self-annihilation (zero state), from whence it is driven back into reality (non-zero state) — only to run back home again to zero.
The sound and shape of the otiot are analogs for the creative energy that generates our world.
No, not the kind of kid you would want in a daycare situation. But think about it a little more, and you’ll see why it has to be that way:
The otiyot are meant to explain more than matter and energy. They are meant to explain why there is anything at all. Why are there patterns of nature? Why are there laws of quantum physics? Why is there uncertainty and chaos? Why should anything make sense, or follow any pattern?
It all begins here: The fundamental substance of the universe is not matter, not energy, not strings, not vibrations, not a set of laws, not intelligence. Fundamentally, the universe is generated out of something that cannot be defined in any way. That which the Kabbalists call Ohr Ein Sof — Infinite Light.
The Ohr Ein Sof holds the power of existence. After all, that’s what it means to be infinite, undefined and unbounded: It means there are no possibilities that are not open, no boundaries that cannot be traversed — including the boundary of self and other. That is why the most exquisite demonstration of this unboundedness is in the sudden appearance of otherness, of an unlimited set of worlds, each its own realm of self-contained reality — until the ultimate extent of this world, where things appear well-defined, following predictable patterns, and look as though they have no origin other than themselves.
That is the ultimate unboundedness: Extending into that which is other, generating an entity that has so totally lost context with its origin that it perceives itself as all there is — and sustaining it in that state.
On the inside, infinite light. On the outside, tidily finite.
So, here’s this infinity pumping out a neatly bounded creation. If you could peer beneath the hood of this creation, you would see only that unbounded, infinite light. But on the outside, it’s tidily finite. Think a moment, and you’ll realize this is a big problem. Imagine running the 22,500 megawatts of the turbines at the Three Gorges Dam through a flashlight bulb. That’s just big-finite inside smaller-finite. Here it’s the absolute infinite within a (seemingly) absolute finite.
A truly infinite force leaves no room for differentiation within time and space, never mind patterns of nature. How can there be a world if there’s no before and after, up and down, or any consistent patterns?
So, the infinite cannot enter.
But on the other hand, if that infinite creative power is not there within the creation, what else is sustaining its existence?
So the infinite must enter — and remain infinite.
Reality, then, is a paradox. Two opposites must concur: The infinite creative force must be simultaneously both here and not-here.
We experience that dynamic as the phenomenon of time. Not metric, relative time, but the distinctly directional flow of time — a perpetual death and rebirth of the moment now, the sense of “what was is now gone, and now this is gone as well.” That is the ratzo v’shov — running and returning — that articulates one moment from the next. At its essence, then, time is a manifestation of the paradox of concomitant being and not-being. 
This dynamic is also what distinguishes one point in space from another, and any individual creation from any other. The uniqueness of each thing derives from its unique articulation of ratzo v’shov, its particular relationship with the infinite. The oscillation is deliberate, with varied articulation, and thus the multifariousness of the creation. Each created being and each event is the result of a set of particular articulations of that oscillation between being and not-being. Each of those articulations is represented by a Hebrew letter, twenty-two in total.
Vibration, it turns out, is the paradox of reality in action.
The Cosmic Symphony
Perek Shirah is a wonderful and wondrous ancient work, likely pre-dating the Mishnah, and attributed by some to King David,  or King David and his son, King Solomon.  It describes the songs sung by the sun, the moon, the earth, the waves of the sea, the trees, lions, chickens, dogs, frogs and many other critters. Each critter, it seems, hums a different tune.
But it’s more than that. From the way this song is explained, it seems that it’s not just that the critter hums. The critter is the hum. No hum, no critter. 
The notes of each being’s song are encoded in the name it is called in Hebrew, the language of creation.  Not a word as we know words, but a manifestation of a divine creative thought. As each thought of G‑d oscillates between being and not-being, selfhood and reabsorption within its source, each according to its part in the Grand Symphony of creation, so it vibrates and sings its unique melody of praise to its Creator. Those letters of a creation’s name, they are the resonance tones of its vibration, constantly sustaining its existence.
The trees sing their song, the grass sings its, the carrots sing another; the frogs, the dogs, the hippopotamus and the Sasquatch. Every cell, every element, every particle has its song in which it is united with all of its species, harmonized with all the universe, and perfectly bonded with the Infinite Light from which it is generated. When that vital light amplifies its signal, the song is magnified and that creature is full of life. Should the signal decrease, the creature winds itself down.
And if its song would be silenced for a moment, in a nanoblink a phenomenon once embedded in our reality would fall from existence into the utter void, to become a non-being that never was. The very memory of it would cease to be, for the song is beyond time, and generates all of time, present, future and past.
It would be as though we had removed the code for an object from the program, and ran the code again. It never was.
There seems to be some correspondence here between a very old Kabbalistic idea and the strongest competitor for the Unified Field Theory.
Maybe I’m the only one seeing this, but there seems to be some correspondence here between a very old Kabbalistic idea (which, as we noted earlier, is well-grounded in the Genesis narrative) and the strongest competitor for the Unified Field Theory. It even explains why these vibrating entities are fundamental to existence — because the otiyot, to generate a finite reality, must be in a constant state of oscillation between finite being and annihilation within the infinite.
Of course, there are also vast differences. Strings are not observable because we don’t have anything small enough to bounce off of them, because they are one-dimensional, and because their vibrations are in multiple dimensions that are also too small for us to observe. The oscillating otiyot are not observable because they do not exist within time and space — they are that which generate time and space. String theory is derived through ingenious mathematical formulas, supported by observation of physical law. Otiyot are known to us through prophetic tradition and divinely inspired intuition.
Nevertheless, I hold hopes that in my own lifetime the two paths of the maze will meet for us. 
Practically Speaking: Oscillating Through Life
With each entry in this series, we need to have a practical application. Kabbalah, after all, is about life, so everything in Kabbalah has a practical application in everyday life. In this case, there’s a pretty clear one:
Just like the otiyot oscillate between existence and nonexistence, so too the lives of each of us.
Are you a something, or a nothing, or both?
Are you a something, or a nothing? If you’re thinking you are a well-defined something, you’re losing out on life. Life is about being open to everything that’s greater and bigger than you. Once you’ve decided, “I am something, and this is what I am” — you’ve shut off growth, new experience and, well, just life.
But then, if you are a nothing, what’s the point of being anything?
Or, as Hillel the Elder stated the classic conundrum:
If I am not for myself,
then who will be for me?
And if I am for myself,
then what am I?
And if not now, when? 
Don’t worry. As we explained, it’s not just you. This is how each thing in the universe exists — it has to both be and not-be, at every moment. That’s why each thing breathes, pumps, oscillates, fluctuates, vibrates, sings, swings and flutters — everything continually traverses back and forth between positive and negative, matter and energy, pattern and chaos, being and not-being, giving and getting, standing up for who you are and sitting down to learn from others. Nothing stands still; nothing just is.
The only thing that just is in this world, now and forever, is purpose. Each of us has a magnificent purpose in being here. Each of us is capable of bringing out the wonder of this creation in some way that no other being can. That purpose is our song, the hum that sustains us, our true essence and being.
And it’s in that purpose that our conundrum is resolved: Don’t be a nothing, and don’t either be a something. Be a something only because your purpose is everything.
Which is why Hillel finished with those words, realizing he is here for a purpose, and asking, “If not now, when?”
 See Rabbi Menachem Mendel of Lubavitch, Derech Mitzvotecha, Mitzvat Ha’amanat Elokut, chapter 1.
 Rabbi Moses of Trani, Beit Elokim.
 Rabbi Elijah Deitz, Pi Eliyahu.
 See Rabbi Schneur Zalman of Liadi, Torah Ohr, Hosafot Ki Tisa 113a; idem, Likkutei Torah, Shir HaShirim 1c; Rabbi Dov Ber of Lubavitch, Torat Chayim, Bereishit 33d ff; and many other places throughout Chabad literature.
 See Tanya, Shaar HaYichud VehaEmunah, chs. 2 and 11–12.
 In his book The End of Science, John Horgan quotes John Wheeler as saying that Kurt Gödel believed that the ultimate answer might already have been discovered and was lying somewhere among the papers of Gottfried Leibniz, the 17th-century German polymath. Leibniz actually did propose an alternative model of the fundamental particle, the monad. Suspiciously, it bears a striking resemblance to the otiyot described here. A recent study by Allison Coudert of Leibniz’s correspondence reveals his familiarity and fascination with the Kabbalah (Leibniz and the Kabbalah, Kluwer Academic Publishers, 1995).
 Avot 1:14.