Mankind has proven itself unworthy and so G-d has decided to press CTL-ALT-DEL. He informs Noach that He will be destroying the world and He gives Noach a Requirements Specification to build an ark that will enable him to survive. The ark that G-d commands Noach to build will serve as a lifeboat. It will need to be able to float on a raging sea, it will need to keep out the rain, and it will need to provide sufficient room to house Noach, his family, and samples of all of the world’s wildlife.
Speaking as an engineer, I am impressed with the design of the ark. Its dimensions – about 150 metres long, 50 metres wide and 30 metres tall – gave it a very low centre of gravity, rendering it highly unlikely to capsize. It had a triangular roof that encouraged water runoff. It had venting in order to enhance the exchange of air, sunlight, and methane gas. Even the materials used in the construction of the ark were carefully chosen. G-d commands Noach [Bereishit 6:14] “Make yourself an ark of gopher wood… and cover it inside and out with pitch.” While “gopher wood” appears nowhere else in the Torah, the commentators concur that it was some kind of light wood that would not tend to sink. Suggestions include cork, cedar, and wicker. To prevent water penetration, the ark was doubly covered in pitch.
Two medieval French commentators, Rabbi Hezkiah bar Manoach, known as the Chizkuni, and Rabbi Yitzchak ben Asher HaLevi, known as the Riva, raise some concerns as to the use of pitch. In Noach’s time, pitch was most likely made from plant resin. Modern baseball players would call this substance “pine tar”. Pine tar has a long history as a maritime sealant. The problem that the Chizkuni and the Riva have with using pine tar to seal the ark is that pine tar has a melting point of about 60 degrees Celsius. Above this temperature, pine tar no longer adheres to the wood and water penetration will occur. As most bodies of water are much cooler than 60 degrees Celsius, sealant melting is typically not an issue. But things were different in the Noach’s deluge. According to the Talmud in Tractate Zevachim [113b], the flood waters were boiling hot. How, ask the Chizkuni and the Riva, could the pitch have remained an effective sealant in these conditions?
Boiling flood water was problematic not only for the pine tar. According to the Talmud, Og, a giant who eventually became the King of Bashan, escaped the deluge by hanging on to the side of the ark. During the entire flood, he was dangling in the flood waters. If the waters were boiling hot, how did Og survive? The Chizkuni offers two answers. His first answer is that even though the pitch should have melted, it miraculously remained solid. The Chizkuni calls this a “miracle within a miracle”. In his second answer, the Chizkuni asserts that while the flood waters were indeed boiling hot, the waters in the immediate proximity of the ark were sufficiently cool to prevent the pine tar and Og from melting.
The second explanation of the Chizkuni opens up a can of worms. To understand why, we must understand some concepts in thermodynamics. It is well known that anything that flies through the air – a missile, a car, or even a bird – heats up. The faster the object travels, the hotter it gets. In one program I worked on, the missile travelled at five times the speed of sound. It became so hot that we had to take precautions so that its internal electrical components did not get fried. Why does an object traveling through a gas or a fluid heat up? One might suggest that the molecules in the gas impact the object and thus impart heat but that is a misconception. Let’s look at a missile flying through the air. It turns out that the surface of the missile’s wings and body have a certain amount of stickiness, which attracts air molecules in the same way that flypaper attracts flies. When fast-moving air molecules become stuck to the missile’s surface, their kinetic energy is transformed into heat, similar to the way a car’s brakes heat up when they are continually applied. The layer of air that sticks to the missile’s surface is called the “boundary layer” and its temperature is called the “stagnation temperature”. If the stagnation temperature is sufficiently high, the heat dissipated into the missile will fry its innards. As the distance from the missile’s surface increases, the effect of the boundary layer decreases until it eventually disappears altogether. The aerodynamic boundary layer was first defined by the German physicist Ludwig Prandtl, soon after the turn of the twentieth century.
Let’s return to the ark. Assuming the ark was in the water for a sufficiently long time, it would have attained the ambient temperature, that is, the temperature of the flood-waters. Now assuming that the flood waters were raging, the temperature close to the ark, at the boundary layer, would have been hotter than they would have been further from the ark. That is to say, if the pitch (or, for that matter, Og) could not withstand the heat of the flood-waters, then there is no way they could have withstood the heat at the boundary layer. The pitch would most certainly have melted and water would have begun to penetrate the ark. This seems to render the second answer of the Chizkuni scientifically incorrect.
The easiest thing to do would be to assert that the Chizkuni, the Riva, and the Talmud were not familiar with twentieth century thermodynamics and so we should disregard the second answer of the Chizkuni. But that would be too easy. Let’s take a closer look at the first answer of the Chizkuni: the pitch did not melt because it was “miracle within a miracle”. The first miracle would be the pitch remaining solid at temperatures above its melting point. But was is this second “miracle” within which the first “miracle” lies?
To answer this question, we return to our boundary layer. While scientists understand the boundary layer well enough to predict how a wing will fly through the air or a boat will sail through water, there are certain things that they don’t know. For instance, in certain locations, the flow in the boundary layer transitions from a clean (laminar) flow to a messy (turbulent) flow. Scientists are not sure what drives this transition. Other physical phenomena are similar. Scientists know how to precisely calculate the force of gravity between two objects – airplane flight depends on this – but they have no idea why the force of gravity exists and they may never know. For all they know, gravity is a miracle. This is how we should understand the Chizkuni: Our would is built around axioms. We can measure them, we can model them, and we can predict them, but we may never be able to understand the underlying mechanism. They are, for all intents and purposes, miracles. So when the Chizkuni said that the water around the ark was somehow cooler than the ambient water, he can be understood as saying that this is an example of a specific “miracle” within the general “miracle” that is the boundary layer. If we accept that G-d can create laws of physics, then we must also accept that He can modify them at will. It is one of the perks of being master of the universe.
Shabbat Shalom and stay healthy.
Ari Sacher, Moreshet, 5781
Please daven for a Refu’a Shelema for Yechiel ben Shprintza, David ben Chaya, and Iris bat Chana.
 Only after G-d tells Noach how he should build an ark does He mention that He will be destroying the world with a deluge. It would have made more sense had G-d told Noach  I’m fed up with mankind,  I will be bringing a flood to destroy them, and therefore  in order to survive the flood, here is the design for an ark. This reverse of cause and effect is reminiscent of the beginning of Parashat Teruma [Shemot 25:1-8] where G-d tells the Jewish People to donate gold, silver, and other precious substances, and only afterwards does He tell them that these materials will be used to build a Mishkan (Tabernacle).
 Certain authorities, led by Rabbi Gedaliah Nadel, assert that the flood occurred only in the Middle East, significantly reducing the number of animals that the ark would have to carry.
 Og was not holding on to the ark by himself. According to the Talmud, Og was joined by the “reima”, a massive animal identified by the King James Bible as a unicorn, which was too large to fit in the ark. Our Sages in the Midrash add Sichon, the Amorite King, whom the Jewish People defeated in battle immediately before they defeated Og, to the list of stowaways.
 The Riva suggests that Og’s body was large enough to withstand the heat.
 This is due to the law of conservation of energy
 Solving this problem is no easy task. Sometimes ablative (burn-away) coatings are used and sometimes heat sinks are placed inside the missile to keep the heat away from sensitive parts.
 The Chizkuni had no idea what a boundary layer was. This is a 20th century concept. Nevertheless, the Chizkuni believed that while our universe might work according to well-defined and seemingly unchanging physical laws, G-d can change them if He so desires.