By: Mr. Yarone Tokayer, Physics Teacher
Light moves astonishingly fast: so fast that it can travel around the world 7 times in one second. But however fast light is, its speed is not infinite. That is how I begin my lesson on the speed of light each winter. It sounds so innocent, that light travels at a finite speed. But once I point out one consequence, a whole can of worms opens up. Bear with me: For us to see anything, light from the object must hit our eyes. Now, that light needs to travel from the object, which takes time. Meaning, the image that appears to us is outdated: for close objects, by a fraction of a second; for the Sun, by about 8 minutes; for most stars, by eons. Think about it: if the Sun disappeared, we would not know about it until 8 minutes later. If an alien on some far away planet pointed its telescope to Earth today, it may see dinosaurs from 200 million years ago!
One student last year found this particularly troublesome. She raised her hand and said “No! That is too crazy to be true.” Each step of the logic made sense to her, but she could not accept the conclusion that we see objects not as they currently are, but as they were in the past. When she found me in the hall the following day, I expected another challenge to the lesson, but to my surprise, the student said, “You know I was thinking about the light thing last night, and I realized that we can be seeing stars that no longer exist!” She was 100% correct, and we went on to discuss how astronomers use this fact to map the history of the universe. The farther away we see, the closer to the beginning of time we get.
My colleague and mentor, Mr. Ron Zamir, has taught me that the best lessons elicit a sense of wonder from students. These are the ones that challenge students to face their initial disbelief, and then push them to discover far-flung implications on their own, as they slowly digest the new information over the course of days. By grappling with the notion of the speed of light, my student had a profound discovery. She internalized the lesson in a way that can only be done through a sense of wonder. In his television program Cosmos: A Personal Voyage, the great Carl Sagan considered why people find the phenomenon of the finite speed of light so compelling. He conjectured that our inability to seize the present speaks to the limits of our reach. Furthermore, the existence of an entire universe before life on Earth formed undermines our self-importance. We are “johnny-come-latelys” of the 13.7 billion year old universe, he said.
SAR High School’s motto is “It’s not just what you learn. It’s who you become.” This adage is not just an aspiration for our students, it is also a directive for teachers. It challenges us to frame our curricula in terms of character goals, in addition to the knowledge and skills that we hope to impart. As a physics teacher, I constantly ask myself: what kind of growth can I hope for in my students? What values can I teach in the physics classroom?
For me, the speed of light lesson highlights two ways in which physics can teach us humility:
1. In physics, and in science in general, we learn about the world beyond ourselves and our place in it. The laws of the universe are not subject to human desires, and their existence is independent of our own. Indeed, as we look into the night sky, we see thousands of stars that, if they could see us back, would look at an Earth devoid of any human life at all. I teach my students that physical phenomena cannot be “good” or “bad,” they simply “are.” They are not questions of politics or interpretation, and do not get “invented” by scientists. We do not work to break them, but to operate within them. The study of physics is a sobering reminder that even the most powerful among us, like the mythical Icarus, are bound to the physical world and subject to its laws.
Furthermore, since the scientific revolution, Western culture has shifted from seeing the Earth as the center of the universe to seeing the Sun as the center of the universe; from seeing the Milky Way (our galaxy) as the only galaxy to our current understanding that our galaxy is 1 of 100 billion, and that there is, in reality, no center to the universe. We do not have a “special” place in the physical world.
Once we internalize these harsh truths, we can move forward as responsible citizens and servants of God to work within our physical confines to change the world for the better. Each year, I choose an epigraph for my course outlines, which I share with my classes on the first day of school:
When I behold Your heavens, the work of Your fingers, the moon and the stars that You set in place, what is man, that You have been mindful of him, mortal man that you have taken note of him? Yet You have made him little less than divine, and adorned him with glory and majesty; You have made him master over Your handiwork, laying the world at his feet. (Psalms 8)
As the psalmist discovers and experiences the world, his sense of wonder is two-fold. On the one hand, he has an existential crisis: he perceives himself as insignificant compared to the vast universe. On the other hand, he remembers that as humans, we have access to the universe and to knowledge—it is “at his feet”—which itself is a tremendous gift and responsibility.
The hasidic master Rav Simcha Bunim of Peshischa was famous for teaching that everyone should keep two notes, one in each pocket. One should read “The world was created for my sake” and the other should read “I am but dust and ashes.” Physics balances these two perspectives by being at once empowering and humbling.
Our high schoolers are in an environment that puts them at a high risk for narcissism. As 11th and 12th graders, they are encouraged to accumulate accolades and grades for their transcripts, and to sell themselves to colleges. We champion students’ “achievements,” which can inadvertently nudge a child to a self-serving attitude about school. Outside of school, we live in an age of personal branding (sometimes quite literally, such as in the case of bar/bat mitzvah logos). Every teenager is expected to have Facebook and Instagram pages to help perfect their personas. Furthermore, as society becomes more and more divided by class, community service becomes more formalized and turns into “personal experiences” as opposed to genuine neighborly giving. None of these observations have to be all bad; we need to instill a sense of self-worth in our students so that they develop a sense of agency to live happy lives. However, we must remember to balance that with messages of humility and responsibility toward others. We can allow students to celebrate who they are as teenagers, but we must also set their gaze forward at what they aim to become in their lives as Jewish adults.
In Iggeret HaRamban, Nachmanides writes to his son:
עַל כֵּן אַפָרֵשׁ לְךָ אֵיךְ תִּתְנַהֵג בְּמִדַּת הָעֲנָוָה… עֵינֶךָ יַבִּיטוּ לְמַטָּה לָאָרֶץ, וְלִבְּךָ לְמַעֲלָה;“This is how to be humble: your eyes should gaze down toward the land, and your heart upward.” Humility starts by probing the world around us. When we gain an understanding of who and where we are, we can turn our hearts upward and aspire for greatness. That is my hope for our students, and I believe that learning physics can play a small part in that development. SAR’s theme of tikkun hamiddot (character development) reminds us that as educators, we are not just conduits of information. We are molders of young men and women. Ideally, this is manifest implicitly in our personal behavior as dugma’ot ishit (role models), and explicitly in our classes as we guide students as to how they can internalize what they learn and help it shape who they become.