A day of joyful festivities turned into a day of tears and mourning. When tragedy strikes, it is not the time for analysis or finger-pointing. Rather, it is the time to bury the dead and to mourn. It is the time to comfort families of the deceased. it is the time to pray that those who survive may fully recover.

However, the tragic irony of this disaster is that it happened to the devout who came to the kever (burial place) of Rabbi Shimon bar Yochai, known as the Rashbi, the second-century tana, to pray for miracles. It happened on Lag BaOmer—the day of the Rashbi’s passing, a day believed to be an auspicious one to pray for miracles. How does one explain to children that people who came to the tomb of the Rashbi on Lag BaOmer to pray for miracles found not miracles but a tragic end? This begs explanation.

From a spiritual perspective, it is not good to try to explain tragedies such as the Holocaust. As the Lubavitcher Rebbe, Rabbi M. M. Schneerson, often stressed, to explain means to justify. We don’t need to justify acts of G‑d. We need only to demand that tragedies ought not to happen! In one of his last interviews, the late Rabbi Jonathan Sacks echoed this thought. G‑d doesn’t want us to understand why tragedies happen, he said, because He doesn’t want us to justify and accept tragedies. And yet, children (and adults) ask, “How could this happen?” So, we are forced to confront this tragedy and seek an explanation.

The explanation, as it happens, is not hard to find. The question is not, “How could this happen?” Rather, the question is, “How did this not happen before?” The tragedy at Mt. Meron was a disaster waiting to happen. The Torah forbids us from doing silly and dangerous things, expecting that a miracle will save us. If a man jumps off the Empire State Building to his death, can you blame G‑d for not saving his life miraculously? Something very similar happened yesterday in Meron.

News outlets reported that people died yesterday on Mt. Meron because they were trampled to death in a stampede. A stampede is the uncontrolled collective running of a crowd of people or a herd of animals. Startled by somehing unexpected, a herd of animals starts running uncontrollably as one. If not redirected, they may run off a cliff or into a river. When fear takes over, it suppresses the instinct of self-preservation, which makes the behavior of a stampeding herd unpredictable and very dangerous.

Stampedes, however, rarely lead to death. But crushes do. What happened yesterday on Mt. Meron was likely not a stampede, but a crush, in which the crowd collapses upon itself. The risk of crushes exists when the density of the crowd exceeds four people per square meter. When the density increases to six or seven people per square meter, individuals pressed against each other lose the ability to move independently. Instead, the behavior of a crowd at this density resembles the behavior of fluids when masses move in waves. A shockwave caused by the movement of a few people (often when one person stumbles and falls) propagates through the crowd, moving the entire mass as one. People squeezed in this shockwave die from asphyxiation, because they cannot inhale. They die while standing, not from being trampled.

The inaccurate description of the accident as a stampede is unfortunate, because it depicts the unfortunate victims as a mindless mob running to save themselves. The opposite is true—people cannot run because they cannot move. They die from being unintentionally squeezed by those around them who are involuntarily moved by the shockwave propagating through the crowd. It is the shockwave that pushes people against each other, causing them to suffocate.

History is replete with tragic human crushes. On May 18, 1896, during celebrations after the coronation of the last Russian tsar, Nicholas II, 1,389 people died and over 1,300 were injured in Moscow in what has become known as the Khodynka Tragedy. On July 2, 1990, 1,426 people were killed in a tunnel on the way to Mecca tunnel during the annual Hajj pilgrimage. This tragedy recurred fifteen years later when, in 2015, at least 2,177 people died in Saudi Arabia during the annual Hajj pilgrimage to Mecca.

The tendency is the blame the victims, particularly when a crush occurs during a religious pilgrimage. That blame depicts the pilgrims as religious fanatics who are responsible for the disaster visited upon them. Usually, the opposite is true—the fault usually lies with the organizers. After the infamous Hillsborough disaster on April 15, 1989—a fatal human crush during a football match at Hillsborough Stadium in Sheffield, England, where 96 people died and 766 were injured—crowds were blamed at first. Only later, after careful analysis, was it determined that multiple preventable errors made by the event organizers led to the crush.

To prevent such tragedies, authorities and event organizers must ensure that the density of crowds during religious, sporting, or entertainment events never exceeds four people per square meter. People should be educated that when they feel the touch of nearby person on all four sides, the situation is unsafe. But when they begin to feel pressure from all four sides and, particularly, no matter how mild, danger is imminent.

What causes the crush or a stampede is another matter. Predicting such events requires knowledge of the physics of complexity. Human crowds are complex systems and behave in some ways like many other complex systems—snow, earth, or the stock market. Predicting a so-called black swan, a rare, uncontrollable event with severe consequences—such as a crush in a large crowd—may be similar to predicting an avalanche, an earthquake, or a market crash, which all follow the power-law distributions. During an earthquake, for example, a few large temblors are followed by many more minor tremors. When stress accumulates in the earth’s crust, even a tiny tremor may cause a significant earthquake. When stress builds up in the snow on a mountain, the utterance of a single loud word can cause an avalanche. When stress accumulates in the stock market, an otherwise insignificant event or a false rumor can crash the market. It is well known that when a complex system reaches a critical state due to accumulated stresses, it becomes unstable, and even a minor perturbance can lead to a catastrophe.

The physics of complexity predicts that the more disorder is found between individual elements that make up the system, the greater the likelihood of an avalanche, earthquake, or crush. It may be noteworthy that this conclusion of the physics of complexity is in perfect harmony with Jewish thought. According to the great Kabbalist, the Ari-zal, kedushah (holiness) only rests where this is order; disorder is the domain of kelipah (unholy shells). Physics—and Kabbalah—suggest that maintaining order is crucial to decrease the likelihood of a crush or another catastrophic event caused by the rising instability in a complex system. Chaos in crowds coupled with the high density of the masses leads to crushes—which is not a counterintuitive conclusion. Event organizers must take steps to ensure that the density of crowds does not exceed the critical density of four people per square meter, and the procession moves in an orderly fashion.

May those who were injured on Lag BaOmer be healed, and those who lost their loved ones be comforted. This tragedy could have been prevented with better planning. Let us make sure it is never repeated.