Generally， university professors are perceived as highly accomplished individuals who have followed a straightforward academic path， often pursuing bachelor’s， master’s， and doctoral degrees consecutively， with post-doctoral research being a natural progression.
However， a recent news item has surfaced about the renowned mathematician Zhang Yitang， who has joined Sun Yat-sen University. His resume notably includes a period of part-time work at Subway.
This stint lasted for a period of seven years.
Remarkably， after this period of employment， he went on to solve a world-class mathematical problem.
The public reaction has been a mix of astonishment and lighthearted commentary. Some joke that working at Subway was merely a role as a technical consultant for a Fortune 500 catering giant.”
Furthermore， Subway’s official social media account even chimed in with a clever public relations move， stating that Professor Zhang is equally professional in making sandwiches as he is in mathematics.
While this narrative might seem reminiscent of a rags-to-riches story often found in fiction， Professor Zhang’s actual journey is far more complex and intriguing than it might appear.
As a child， Zhang Yitang was unequivocally a prodigy. At the age of 8， he was already delving into the mathematics section of “Ten Thousand Whys.” By 9， he independently discovered the Pythagorean theorem， and by 12， he was studying calculus.
At the same age， my peak intellectual achievement was figuring out my family’s computer password.
His early experiences ignited a profound passion for mathematics. In 1978， he enrolled in the mathematics department at Peking University.
This was followed by a typical trajectory for a gifted student: a combined bachelor’s and master’s program， and then， as a government-funded self-sponsored student， he pursued his doctorate at Purdue University in the United States.
One might assume this set him on a direct path to the pinnacle of his career.
However， upon arriving in the United States， his ascent seemed to stall. Although he has always been reluctant to discuss this period， it is widely understood that he experienced conflicts with his advisor. This is supported by the fact that while he completed parts of his doctoral dissertation in just two years， his graduation took seven years.
After finally obtaining his doctorate， he did not receive a letter of recommendation from his advisor. Such a letter serves as a crucial gateway into the academic world. Moreover， he was unwilling to take on any work outside of mathematics.
A graduate of Peking University and a doctorate from Purdue， he found himself in a state of relative academic idleness.
Unable to secure a suitable position， he accepted an offer from a Peking University alumnus to work as an accountant at Subway. This choice was also strategic， as it allowed him time to study mathematics during his less busy moments.
This demonstrates the adage that strong individuals do not complain about their circumstances; the juxtaposition of “slacking off” and “studying mathematics” is quite remarkable.
This period of his life became a focal point for criticism from some netizens. Some accused him of looking down on domestic universities by choosing to work in a fast-food chain rather than returning to China.
The criticism is indeed perplexing， but upon reviewing his past interviews， it’s worth clarifying this misconception.
He once stated publicly: “Societal pressure is immense; you cannot escape it. If you don’t publish papers， adverse consequences will follow. I could remain patient and forgo these things， but my family and friends would not agree.”
This sentiment is undeniably true. During family gatherings， most people have experienced relentless questioning from relatives about their jobs， income， and relationship status.
While we might endure such inquiries， Zhang Yitang was concerned that this pressure would interfere with his mathematical research.
Therefore， Zhang Yitang’s apprehension was likely not about returning to China， but rather about the pervasive social dynamics and worldly expectations within a familiar environment.
Another contributing factor was his inherent pride. He felt that returning without significant achievement would be a source of embarrassment.
Consequently， he continued to strategize his mathematical pursuits while working odd jobs at the fast-food chain. This strategic period spanned over two decades.
During this time， his Peking University alumnus also helped him secure a teaching position， affording him more time to dedicate to his mathematical endeavors.
Later， he began to suspect he was on the verge of a breakthrough concerning the “twin prime conjecture.” He described his feeling as: “I had an intuition， an intuition that told me I could solve it.”
His remarkable focus is truly astonishing. It’s not surprising that such intuition is attributed to figures whose work fills mathematics textbooks.
This intuition became the opportunity for his ultimate recognition.
In July 2012， while resting in a friend’s backyard in Colorado， doing nothing but contemplating—perhaps observing deer—a sudden flash of insight struck him.
Like a lightning bolt， a critical bottleneck in the proof of the “twin prime conjecture”—a problem that had challenged him for years and the entire mathematics community for over a century—was instantaneously overcome.
According to his recollection， the entire thought process formed within mere minutes.
This experience can be likened to repeatedly failing at a video game boss fight， taking a break， and then succeeding on the next attempt.
He promptly wrote up this breakthrough idea and submitted it to “Annals of Mathematics，” one of the most prestigious journals in the field.
The journal’s prestige is such that the review process for a single paper typically takes at least a year. However， Zhang Yitang’s paper was accepted in just three weeks from submission.
Even more fascinating is the anecdote about the review process. It is said that Zhang Yitang knew who the reviewer would be before submitting his paper， as there were only a few mathematicians working on such problems. He reportedly tailored his writing style in the paper to match the reviewer’s preferences.
Initial reactions suggested he might be a self-taught mathematician.
Then， a sense of intrigue began to build.
Soon， it became apparent that something substantial was emerging.
Indeed， it seemed to be a genuine breakthrough!
Let’s discuss this conjecture.
In simple terms， the “twin prime conjecture” posits that there are infinitely many pairs of prime numbers that differ by 2， such as 3 and 5， or 11 and 13. Previous attempts to prove this had failed， with mathematicians only able to demonstrate that the gap between prime numbers could be infinitely large.
While this conclusion might seem to offer little practical insight to the layman， it was a significant step.
Zhang Yitang， however， proved the existence of infinitely many pairs of prime numbers whose difference is less than a specific， finite number—70 million.
While 70 million might still seem large to a layperson， in the realm of mathematics， this represents a qualitative leap from zero to a tangible quantity. In essence， he single-handedly moved a seemingly intractable problem into a realm of finite， addressable possibilities.
The subsequent events are likely familiar to many. Zhang Yitang achieved widespread acclaim， receiving numerous prestigious awards such as the MacArthur Fellowship， the Breakthrough Prize in Mathematics， and the Cole Prize in Number Theory.
He has now returned to China and joined Sun Yat-sen University as a professor. Public opinion has drastically shifted， with media coverage and the public’s tendency to elevate figures contributing to his narrative. However， it’s important to acknowledge that such transformations are often amplified by media and a collective desire to celebrate exceptional achievements.
For Zhang Yitang himself， however， this public attention might not be the primary focus.
After all， his achievements are concrete and substantial. An individual who can calmly list his experience working at Subway on his resume likely possesses a perspective that transcends such external validation.
Furthermore， this story offers a charming reminder: the next time you visit a fast-food restaurant， perhaps be a little more courteous to the person serving you. You might just be interacting with the next legendary accountant from Subway.
