The Physics of Noah’s Flood
Ancient tales of a great deluge abound, but there’s none quite so influential as the Noachian Flood. People still produce photos of rills and humps on Mount Ararat that they breathlessly proclaim to be the remains of Noah’s Ark. A creationist museum in Kentucky has built what it claims to be a reproduction of the original seagoing zoo. What was the ark really like? Here’s how the Bible describes it:
Noah was six hundred years old when the flood of waters came on the earth. And Noah with his sons and his wife and his sons’ wives went into the ark to escape the waters of the flood. Of clean animals, and of animals that are not clean, and of birds, and of everything that creeps on the ground, two and two, male and female, went into the ark with Noah, as God had commanded Noah. And after seven days the waters of the flood came on the earth.
In the six hundredth year of Noah’s life, in the second month, on the seventeenth day of the month, on that day all the fountains of the great deep burst forth, and the windows of the heavens were opened. The rain fell on the earth forty days and forty nights. On the very same day Noah with his sons, Shem and Ham and Japheth, and Noah’s wife and the three wives of his sons entered the ark, they and every wild animal of every kind, and all domestic animals of every kind, and every creeping thing that creeps on the earth, and every bird of every kind—every bird, every winged creature. They went into the ark with Noah, two and two of all flesh in which there was the breath of life. And those that entered, male and female of all flesh, went in as God had commanded him; and the Lord shut him in. (Genesis 7:6–16, NRSV)
No wonder the Lord slammed the cabin door, for by now the ark must stink to high heaven. Things can only get worse as millions of corpses bob in the waters. Perhaps to tamp down the stench, God keeps the spigots open for months.
The waters swelled so mightily on the earth that all the high mountains under the whole heaven were covered; the waters swelled above the mountains, covering them fifteen cubits deep. And all flesh died that moved on the earth, birds, domestic animals, wild animals, all swarming creatures that swarm on the earth, and all human beings; everything on dry land in whose nostrils was the breath of life died. He blotted out every living thing that was on the face of the ground, human beings and animals and creeping things and birds of the air; they were blotted out from the earth. Only Noah was left, and those that were with him in the ark. And the waters swelled on the earth for one hundred fifty days. (Genesis 7: 19–24, NRSV)
Okay, so now the entire planet is covered in water to a depth of about 29,000 feet (5.5 miles or 8.8 kilometers). We know this, because Mount Everest currently stands at 29,029 feet above sea level, and 15 cubits more adds another 22 feet, but as we’ll explain below Everest has grown a bit since Noah took to sea. How could this scenario possibly take place without a “magic wand”? Let’s see how far we can get.
First, could Noah really be six hundred years old? Senescence is not fully understood, but much of what we know suggests that he could not live to that age in years as we understand them. Normal human cells can only divide between 40 and 60 times. This is known as the Hayflick Limit. At that point the telomere—a kind of doomsday clock on a cell—reaches its end and the cell undergoes apoptosis, or programmed cell death. There are some cells that avoid this fate, but they are not welcome in our bodies. Such cells multiply for their own benefit. We call them cancer.
So, rather than revise normal human biology, let’s assume that the Earth was both spinning faster and orbiting the Sun faster—by a factor of about ten. This turns out to be a somewhat useful assumption for what will follow.
Now, we are confronted with a big problem: what would it take to cover every bit of landmass on the Earth, and how might that be achieved?
If we idealize the Earth as a sphere, we can approximate how much water would be needed. First, let’s get a measure of the volume of the Earth. (For simplicity’s sake, we’ll work in metric units. Keep in mind that a kilometer is a little more than half a mile. We could make the calculations even simpler by starting with the Earth’s area, but to keep a feel for the process we’ll work with volumes.) The tried-and-true formula for finding the volume of a sphere, which we all remember have forgotten from our schooldays, is (4/3)πr3. Now, the Earth’s radius is 6,371 kilometers. So, plugging numbers into the formula: [(4 x 3.14159)/3] x (6371 x 6371 x 6371)] equals . . . wait for it . . . okay, that gives us roughly 1,080,000,000,000 (or 1.08 trillion) cubic kilometers. Now, we must figure out how much bigger a sphere would be created if the surface of the Earth were one big ocean overtopping the highest mountains. Here, we run into several tricky points, starting with the highest mountain. Is it really Everest?
That depends. From sea level, yes, but taking into account the bulge of the Earth at its middle, Mount Chimborazo in Ecuador has a claim to being taller. If you were on the moon bouncing a laser beam off the surface of the Earth at various points, the summit of Chimborazo would appear closer than the summit of Everest. If the Earth were spinning faster in those days, the bulge would have been even greater. But let’s put aside mighty Chimborazo, because what we want to know is how much extra water it would take to cover all the mountains. Under the centrifugal force of the Earth’s rotation, water will bulge just like land, so sea level should be the relevant measure. In those terms, Everest remains the champ, standing 29,029 feet above sea level. However, as I mentioned above, we can’t assume that it was precisely that height some six thousand to ten thousand years ago, when the Great Flood presumably happened.
Geologists say that the Himalayan Range, including Everest, was thrust up at least 30 million years ago, when the Eurasian plate collided with the Indian subcontinent plate. In recent years, two opposing forces have been manipulating Everest’s height. Lingering upthrust pushes the mountain higher by a few millimeters each year, while erosion caused by the snows that perpetually fall on its peak files it down ever so slightly. Call it a wash.
Even so, in converting from feet to the metric system, we’ll round up the height of Everest from 8.85 kilometers to 9 kilometers to account for those extra cubits the Bible mentions and to make sure the peak doesn’t pop up during low tide. How much difference do those nine additional kilometers make? We need to run the numbers again. (Skip the formula if numbers make your brain hurt.)
Let’s see: [(4 x 3.14159)/3] x (6380 x 6380 x 6380)] equals . . . here it comes now . . . 1.09 trillion cubic kilometers (rounding up a bit). Subtract the 1.08 trillion cubic kilometers of the Earth’s interior volume and we have our answer: we’d need roughly 10 billion cubic kilometers of extra water to flood the Earth so as to cover all the mountains.
That’s a colossal amount of water. A really, really huge quantity. It’s more than all the water on Earth. A lot more. More than seven times as much. At present, the Earth has a bit more than 1.33 billion cubic kilometers of water, with oceans holding roughly 97 percent of that and the remainder found in clouds, glaciers, lakes, rivers, aquifers, etc.
Even though the difference in area between the surface of the Earth and the enveloping sphere of extra water is tiny (about 0.3 percent), there is a significant difference in terms of volume. That’s because volume grows much faster than surface area as you scale up—by the cube versus the square. (It’s why hummingbirds can fly, and pigs cannot.)
We do get a little break, however. The protruding mountains and landmasses themselves displace some of the volume in question, so we can trim our water budget. Not by much, though. Land above sea level only occupies about a third of the Earth’s surface, and of that most lies in plains. Let’s be generous, though, and give ourselves a 20 percent discount on the amount of water needed.
So, where are we going to find 8 billion cubic kilometers of water? That figure still represents roughly six times the amount of water known to exist on Earth. The Moon is big enough to hold that quantity, but transferring such a volume (representing well over 10 percent of the satellite’s mass) to the Earth would have sent the Moon spiraling away from us. If it had been closer to begin with the tides would have swamped the Holy Land long before Noah laid a single cubit of timber down.
Some have argued that we don’t need more water at all. The continents, they say, simply lowered beneath the waterline for 150 days and then popped back up. There are a few problems with this idea. First, rock is denser than water (that’s why it doesn’t float). Therefore if you were to lower the continents, you would cause the Earth to spin faster, like a spinning skater who pulls in her arms. Then, when you pushed them back up, it would slow again. Since everything on the surface of the Earth shares the rotational momentum of the planet, this would be like a cargo plane taking off and landing with a plastic swimming pool in its hold. To say the water would slosh around is understating it. Then there is the unimaginable displacement of all that water as the continents rise and fall. Think of a fat man doing a cannonball into a child’s pool. Noah’s Ark would have been swamped by the largest waves ever seen. Surf’s up, dude.
The idea of continents sinking and then rising again in a matter of months is a nonstarter, anyway. No natural process could account for such antics. That being so, we’re still in the market for water. There is a plentiful source, way out in the Oort Cloud. There, beyond Pluto, in the inky depths of space, lurk innumerable comets, largely composed of water. Comets are like dirty snowballs floating in space. Suppose, then, that two of them were perturbed in such a way that they came streaking toward the Sun and collided with each other just ahead of our planet? Their collision would cause their water content to vaporize and then flash freeze in a beautiful cloud of ice crystals. If the respective momenta were just right, the Earth might overtake the cloud and experience forty days and forty nights of worldwide rain.
There are at least two problems with this idea. First, if we were to dump that much fresh water into the ocean, its salinity would vanish. Ocean life is adapted to living in saltwater; ocean-dwelling fish, marine mammals, plants, and crustaceans can no more live in freshwater than you could in a nitrogen-only atmosphere. Yet, we know that the ocean waters gained their saltiness from interaction with the Earth’s minerals. Finding a presalted comet might be like expecting a hen’s egg to come with its own seasoning in the shell.
Yet, we have to assume that the rainwater of the Great Flood had the same salinity as the oceans; otherwise, Noah would have had to take aboard all kinds of whales, sharks, and every other kind of marine creature that depends on saltwater for life. A single blue whale would be nearly a fifth of the length of the ark (30 meters versus 158 meters).
Assuming Noah could install a tank for the pair of them, a third of the ark’s storage capacity would be gone. As for stocking enough krill to feed the blue whales . . . fuggeddaboutit. Noah’s got troubles enough keeping the crocodiles from polishing off the pigs. As for the Komodo dragons . . . don’t get me started. We have to go with the saline hypothesis.
There may yet be a way to boil up a salt solution. It was long thought that comets delivered the water that today covers two-thirds of the Earth’s surface and makes up the clouds, ice caps, and other features of the hydrological cycle. We know the Earth could not have formed with all that water intact. Its early days were hellishly hot and (as the Moon’s pockmarked surface attests) under constant bombardment. Nearly all the primordial waters would have been blasted away into space.
Later, when cooler volcanic heads prevailed, water returned to the Earth. But how? It’s long been thought that comets delivered it. However, in 2014 a close-up inspection of a comet by the Rosetta Spacecraft threw cold water on that idea. The hitch is this: there are different kinds of water. Most water is made of an oxygen atom plus two ordinary atoms of hydrogen. But a tiny fraction of it is made of oxygen and deuterium, or heavy hydrogen. What makes the deuterium heavy is the addition of a neutron to the proton at the atom’s core. The ratio of regular hydrogen to deuterium in the comet water that Rosetta inspected differed a lot from the ratio we find on Earth.
That led scientists to think again. Maybe asteroids rather than comets delivered the water we find on Earth. Asteroids are largely made up of rocks and minerals. So, could they deliver salt along with water? This is at least conceivable. Would we then be able to turn that cloud into forty days’ and forty nights’ worth of rain, amounting to 10 billion cubic kilometers of water? Improbable, to say the least. Friction is a major problem. That much mass traveling through our atmosphere in such a short period would surely overheat and turn the world into a deadly steam bath. There is a period early in our planet’s history when huge volumes of rain fell as the nascent Earth cooled. It rained and it rained and it rained, filling the oceans to the brim. It took a while, though. The deluge evidently went on for thousands of years. Even the most dedicated YMCA fan would have quit the steam bath by then.
Let’s suppose that by a nearly miraculous coincidence the saltwater crystals left by some deuterium-laden comets required exactly as much heat to melt as they generated by falling through the Earth’s atmosphere, and that they went from ice to liquid water in a single step, bypassing the usual vapor path to rain. Let’s also suppose that in doing so they came in at an angle that slowed the Earth’s orbit and rotation just enough to allow for Noah’s age. That would raise still more problems, mentioned above, about friction and rotational momentum, but we’ll let them go. We’ll assume that it was an almost miraculously gentle braking action—one that gives more time for the rain to fall, as each day becomes longer than the last.
Of course, in saving the ocean’s creatures, we raise the necessity of a huge number of onboard aquariums to accommodate all the freshwater fish, otters, turtles, and other river dwellers that would die in a deluge of saltwater. It’s not clear how Noah would have built aquariums, but maybe he assigned that task to his sons.
That’s only the beginning of the troubles. Boarding is one thing; feeding pairs of every kind of animal on Earth for a little more than a year is quite another. A single elephant, for example, eats up to 600 pounds of fodder a day. For a pair of elephants, Noah would have needed to stow around 10,000 bales of hay on the ark, or risk them going hungry. You really don’t want a hungry bull elephant rampaging on your ark.
But let’s skip past the onboard agricultural challenges to face up to the biggest of them all: how do we get rid of a volume of water far greater than all the world’s oceans in a matter of months? Here’s what the Bible tells us happened:
But God remembered Noah and all the wild animals and all the domestic animals that were with him in the ark. And God made a wind blow over the earth, and the waters subsided; the fountains of the deep and the windows of the heavens were closed, the rain from the heavens was restrained, and the waters gradually receded from the earth. At the end of one hundred fifty days the waters had abated; and in the seventh month, on the seventeenth day of the month, the ark came to rest on the mountains of Ararat. The waters continued to abate until the tenth month; in the tenth month, on the first day of the month, the tops of the mountains appeared.
You might think that after all that time on board, with a cacophony of shrieking peacocks, howler monkeys, roaring lions, and trumpeting elephants (not to mention the flies), everybody would be good and ready for some shore leave. But no. According to Noah, it’s still too soggy outside. The old hydrophobe makes them all wait another forty days before he even tests for dry land . . . ever so cautiously:
Noah opened the window of the ark that he had made and sent out the raven; and it went to and fro until the waters were dried up from the earth. Then he sent out the dove from him, to see if the waters had subsided from the face of the ground; but the dove found no place to set its foot, and it returned to him to the ark, for the waters were still on the face of the whole earth. So he put out his hand and took it and brought it into the ark with him. He waited another seven days . . .
They’re on a mountain, fer chrissakes. Can’t they at least get out and stretch their legs?
. . . and again he sent out the dove from the ark; and the dove came back to him in the evening, and there in its beak was a freshly plucked olive leaf; so Noah knew that the waters had subsided from the earth. Then he waited another seven days, and sent out the dove; and it did not return to him any more.
Finally! I lost track of how many days and nights this took, but relying on the good apologists at DefendingGenesis.org, I believe it was no less than 335 days from the end of the flood to day of disembarkation. That’s a hellishly long time for anyone to be cooped up on an ark. But is it truly enough time for all that water to recede?
Problem. The mutual attraction law of gravity creates a one-way street. (Or warped spacetime, if you prefer to be Einsteinian, but in this context it amounts to the same thing.) Anything can fall onto the planet, but without the force of a rocket, nothing can get off. To leave the planet, an object has to exceed the minimum escape velocity, which is just over 25,000 miles per hour (or 11 kilometers per second). At that speed, you could travel from New York to Los Angeles in about seven minutes. Don’t count on being served a drink along the way.
It takes enormous power to accelerate objects for long enough to get out of the clutches of Earth’s gravity. The Saturn V rocket, the most powerful in NASA’s fleet, needed to generate nearly 30 kilos of thrust for every kilo of cargo it put into low-Earth orbit. Keep that in mind as we click through some staggering numbers: a cubic meter of water weighs a metric ton. Now, you might think that a cubic kilometer has a thousand cubic meters in it, but that would be wrong. A cubic kilometer runs to a thousand meters per side, but within the box that forms are a million cubic meters. So, to shift 8 billion cubic kilometers off the surface of the Earth, we’d need at least 30 x 1,000,000 x 8,000,000,000 kilos of force. That’s 2.4 x 10^17, a number so big that it doesn’t have its own name. We call it a hundred quadrillion. It’s, uh, ten times a million times a billion. In other words, it’s abso-freakin’-lootely huge.
Yet, there are forces in the universe capable of the job. The solar wind, for example, has blown most of the atmosphere and water off the surface of Mars. Of course, that’s taken billions of years, and the gravity of Mars was only about 40 percent of Earth’s to begin with.
There is at least one cosmic tool that can get the job done on time. A gamma ray burst could flash-vaporize and blow the water away in a jiffy. Gamma ray bursts are somewhat mysterious cosmic lightning bolts, carried by high-energy photons streaking across space. They are thought to emanate from stars with nearby massive planets that wind up their magnetic fields until they snap.
The trouble is that a gamma ray burst with the power to blow away that much water would sterilize the planet like God’s own autoclave. The laws of thermodynamics say that you just can’t heat up water that fast and blow it away without the heat spreading. The energies required for the job would be globally catastrophic. Mount Ararat, where Noah’s Ark supposedly came to rest, would be the scene of a flash-fry barbeque of every living creature left on Earth. Pass the Famous Dave’s . . .
Could the water have drained into vast caverns under the sea? That idea has been kicked around, but it’s a no-hoper. The Earth’s gravity draws everything toward its center of mass. Only the interposition of something denser prevents an object from continuing its journey to the center of the Earth. You’ve probably known this since childhood days in the bath. If you press a rubber ducky to the bottom, it will pop up when you release it, because the air inside it is much less dense than the water in the bath.
It’s true that electromagnetic forces, being far stronger than gravity, can temporarily offset gravity’s pull for some objects. A steel truss bridge, held together by electromagnetic force between its atoms, can keep a roadway suspended above the air for a lifetime or more. But even the best bridge has a load limit. Any attempt to hide a vast ocean of boiling water (it’s hot down there!) under a crust of rock would eventually give way. The first volcanic eruption would spurt all that water back up to the surface as the rock pressed downward, and it would be steam bath time all over again.
In any case, we know that there isn’t a second ocean hidden under the Earth’s crust. Even though no one has ever drilled into our planet’s interior (the crust is just too thick), scientists have mapped it in detail.
How? The same way that an expectant mother can get an image of her fetus: by sonogram.
When earthquakes occur, seismic waves rattle through the Earth, and seismologists can read the information they carry to the surface to create a portrait of the Earth’s core.
The only other natural solution would be a black-hole vacuum cleaner. Black holes can, in principle, absorb a limitless amount of stuff. (In practice, astrodynamics limits them to gobbling up a decent chunk of a galaxy before the stellar winds and rotational forces put other stars out of reach.) So, in principle, a black hole could soak up all the excess water and leave Noah high and dry. The trouble is that, unlike a Hoover, black holes don’t have an off switch. Any black hole that started to feast on the Earth’s bounty just wouldn’t quit. It would consume the entire planet like a glutton slurping up a plate of spaghetti. Black holes are a dead end.
But here’s the weirdest thing of all. In a passage that never seems to get quoted, the Bible tells us that at the end of the voyage, Noah roasted at least one of every kind of animal:
Then Noah built an altar to the Lord, and took of every clean animal and of every clean bird, and offered burnt offerings on the altar. And when the Lord smelled the pleasing odor, the Lord said in his heart, “I will never again curse the ground because of humankind . . . ” (Genesis 8:20–21, NRSV)
This makes it highly improbable that we would have any elephants, pandas, polar bears, or orangutans today. These slow-reproducing creatures are quite unlikely to have become impregnated or given birth during the voyage—especially not with all the other animals watching.
So, in the end, we are stumped. What a wild and pointless ride. After all that, the world is still full of sin and cockroaches. No wonder Noah got blind drunk when it was all over.
The sober truth is this: either Noah’s Flood is a tall tale gone wild, or God is a magician after all.
This essay is excerpted from It's a Miracle!?: What Modern Science Tells Us about Popular Bible Stories, , which is available for purchase at these paid links: Amazon, Bookshop, and Pitchstone.
Clay Farris Naff is an award-winning journalist and author. He has been a Tokyo correspondent for United Press International, a freelance reporter for National Public Radio, and a freelance writer for Newsweek, Earth Magazine, Humanist, and Scientific American, among other publications.