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Volume 4145


Deflating the rubber balloon.
By Rick Johnson
Note:  all quotes are from A Princess of Mars

On thing that struck me when I was watching both the  John Carter (Disney)  and Princess of Mars (Asylum) movies is how far John Carter was able to jump!  In the John Carter movie, Kantos Kan rescues John Carter, leads him to a window and points to a tower hundreds of feet away telling him that he must jump there CARRYING Kantos Kan!!!  In the Princess of Mars movie, he is able to leap to the top of a very large arena without effort. Both films show our hero performing the most amazing feats without any effort at all.  At least I never saw JC bent over trying to breathe even though the air pressure on Mars/Barsoom is supposedly so low and his efforts are so great.  He leaps hundreds of feet as casually as would a normal person climb a low set of stairs.  What a man!


Ok, a little info here.  John Carter is described by Burroughs as:

 I well remember the tall, dark, smooth-faced, athletic man whom I called Uncle Jack.
He was a splendid specimen of manhood, standing a good two inches over six feet, broad of shoulder and narrow of hip, with the carriage of the trained fighting man.  His features were regular and clear cut, his hair black and closely cropped, while his eyes were of a steel gray, reflecting a strong and loyal character, filled with fire and initiative.
Athletic!  Not an athlete!   Athletes are professionals who focus on a few sports at which they are very good!  An athletic person is one who is in good shape and can do many things, but none as well as an athlete.

As an example, in my time I was a long distance runner (but couldn’t win a sprint if a lion were chasing me), an archer, fencer, kendoist, katateka (that means I did Japanese sword fighting and karate) and some gymnastics.  But when it came to the shot-put or pressing iron, I was lost.  I simply had neither mass nor strength, though I did have endurance and agility and speed.

John Carter was a horseman, a fencer (cavalry saber) and perhaps a boxer.  Plus by the time he reached Barsoom, I would imagine those months swinging a pick gave him some decent shoulders (at the expense of flexibility).  So he was in good shape, but hardly an Olympic Athlete.

Yet, when he reached Barsoom, a world with a lesser gravity, he was able to kill a Thark with a single punch:

As he banged me down upon my feet his face was bent close to mine and I did the only thing a gentleman might do under the circumstances of brutality, boorishness, and lack of consideration for a stranger's rights; I swung my fist squarely to his jaw and he went down like a felled ox.  As he sunk to the floor I wheeled around with my back toward the nearest desk, expecting to be overwhelmed by the vengeance of his fellows, but determined to give them as good a battle as the unequal odds would permit before I gave up my life.
Now I’m good!  Or was.  I have put my opponent into the hospital with a single blow and with a practice sword, damaged a man twice my size to such an extent they had to cut his body armor from his moaning body so I can only imagine the force it took to kill that 12 foot Thark.
And here is where it gets interesting…  When JC arrives upon the red planet, he finds that his efforts to rise…
Springing to my feet I received my first Martian surprise, for the effort, which on Earth would have brought me standing upright, carried me into the Martian air to the height of about three yards.    [POINT ONE]
And when he attempts to walk…
Instead of progressing in a sane and dignified manner, my attempts to walk resulted in a variety of hops which took me clear of the ground a couple of feet at each step and landed me sprawling upon my face or back at the end of each second or third hop.  My muscles, perfectly attuned and accustomed to the force of gravity on Earth, played the mischief with me in attempting for the first time to cope with the lesser gravitation and lower air pressure on Mars.  [POINT TWO and POINT THREE]
Our hero is approaching an enclosure that is some four feet in height, the roofed incubator of the Tharken hoard and upon examining the structure, is surprised by the Tharks who wish him dead:
 Consequently I gave a very earthly and at the same time superhuman leap to reach the top of the Martian incubator, for such I had determined it must be.
My effort was crowned with a success which appalled me no less than it seemed to surprise the Martian warriors, for it carried me fully thirty feet into the air and landed me a hundred feet from my pursuers and on the opposite side of the enclosure.
Now remember that JC had heard a slight sound, turned around and was facing Tars Tarkas whose approaching lance was but 10 feet from his breast.  So, John Carter leapt up and backwards 30 feet up and 100 feet backwards!  We are talking about a reverse standing long jump!  Try it!

Upon being taken to the Dead City where the Tharks are resting, he is told to:

…he said, "sak!"  I saw what they were after, and gathering myself together I "sakked" with such marvelous success that I cleared a good hundred and fifty feet; nor did I this time, lose my equilibrium, but landed squarely upon my feet without falling.  I then returned by easy jumps of twenty-five or thirty feet to the little group of warriors.
Ok, I can go on and on with these examples of Captain Carter’s marvelous expressions of his physical abilities but as I am not being paid by the word, I see no reason to bore you.  Instead we will take a few notes from Earth:


The Olympics are those sporting events that attract the greatest of the amateur(ha) athletes in the spirit of friendly competition(double ha).  So here are some stats:

The average long jump from a standing position is between 2.1 and 2.2 meters.  The world record for the standing long jump is currently held by Arne Tvervaag who, in 1968, jumped 3.71 meters.

In 1991, Mike Powell set the current world’s record of 8.95 meters or 29.4 feet (in 1920 it was 7.7 meters and extrapolating backward, by John Carter’s day it should be around 7 meters).  Now remember that this man was a trained athlete who worked hard most of his life to do this one task.  The average would be about 7 meters or 21 feet.

The worlds record for the vertical high jump (from a standing position) is held by Kadour Zi and is 155 cm or 61 inches.  The Average is between 0.5 to 0.75 meters or 21-30 inches, less than half Kadour’s record.

The average running long jump is between 2/21 and 2.3 meters or 7 feet to 7 feet 6 inches.

Let’s chart this:

STANDING LONG JUMP 2.1 – 2.2 m 6 ft
STANDING HIGH JUMP 0.5 – 0.75 m 21 -30 in
RUNNING HIGH JUMP 2.21 – 2.3 m 7 – 7.5 ft
Now I MUST emphasize that these distances are for people in good condition who are preparing for the event.  That means that they are rested, well-fed, told how to do the jump and given a series of attempts to gain experience with rest breaks between every attempt.  In other words, a college gym class.  Try this yourself.  Go to the park with a friend and sak!  Try to sak repeatedly without a rest break and your distances will drop as you tire.  Have your friend measure you and I suspect that you will fall well below these stats.  I know I did.

So, John Carter, on Earth, should be able to jump:

 Standing long jump => 6 feet
 Running long jump => 20 feet
 Standing high jump => 30 inches
 Running high jump => 7 feet
(rolling his body over a bar.  To leap to a table, maybe 3')


When the astronauts visited the Moon, they did experiments on jumping to see if the math worked.  Once they compensated for wearing that bulky and heavy suit (195 pounds), the math actually was true so using the Moon as an example, we can extrapolate for Mars.

Here are a few things to know before we go further.

Mass is the total amount of matter in your body.  This is basic and the same no matter where you are.  Let us assume that John Carter is an average build man and so at 6’ 2” he should weigh about 81.6 kg or 180 pounds.  But he’s been swinging that pick so let’s bulk him up a bit to 88.4 kg or 195 pounds.    So John Carter would have a MASS of about 195 pounds.

Weight is a function of gravity and mass.  If Earth = 1.0, then on Earth John Carter would have a WEIGHT of 195 pounds.  But, on the moon with 16% (1/6th) Earth gravity, JC would weigh 195 x 16% = 31 pounds.  On Mars with .38 Earth gravity, JC would weigh 74 pounds.

Here is the IMPORTANT THING:  John Carter will weigh 74# on Mars but his mass remains at 195#!  We’ll get to that later.

The math is very simple, and enough experiments have been done on Earth along an angled wall and in a gym (compensating the math) to give some conclusions that were proven by Armstrong and the others on the Moon.  To find out how far you can jump on the moon, you take the average stats I provided and multiply them by 6!
             Gravity on Moon = 16.6% of Earth => 1.00/x = 16.6/100 => 6.02
That’s it.  It isn’t perfect and I am certain that MIT, Cal-Tech and JPL will point out minor errors in my thought experiment (you forgot to compensate for planetary rotation and the vicinity of large mountains and you only calculated to two decimal points….) Blah blah blah…  This isn’t rocket science, it’s a simple thought experiment!

So if we assume that John Carter is an athletic person in the prime of his physical abilities, he SHOULD be able to do the following, the first time.  Note that as he tires, each successive jump will be shorter.

STANDING LONG JUMP 6 feet  36 feet
RUNNING LONG JUMP 25 feet 150 feet
STANDING HIGH JUMP 30 inches 15 feet
RUNNING LONG JUMP 7 feet 42 feet
Impressive, isn’t it!  And here is the curious thing.  Read Princess of Mars again and you find that John Carter is jumping around and getting results one would expect on the MOON!

If we do the same math but plug in the numbers for Mars at 0.38% Earth Gravity, we get the following:
         Gravity on mars = 0.38% of Earth => 1.00/x = 38/100 = 2.63
Ok, JC isn’t THREE times as strong, he is only 2.63 times as strong.  So we multiply these numbers by 2.63 and get the following chart (rounding off):

STANDING LONG JUMP 6 feet  15 feet
RUNNING LONG JUMP 25 feet 65 feet
STANDING HIGH JUMP 30 inches 6 feet
RUNNING LONG JUMP 7 feet 18 feet
STANDING LONG JUMP 6 feet  15 feet  150 feet
25-30 feet
150 feet backwards
50 feet backwards
RUNNING LONG JUMP 20 feet  60 feet Roof to roof
STANDING HIGH JUMP 30 inches 6 feet 30 feet
RUNNING HIGH JUMP 7 feet 18 feet 40 feet
Considering that the worlds record Running Long Jump holder (29.4’) by a professional athlete, he  should be doing 77.3 feet  on Mars which is about half of what untrained John Carter did his first day on Barsoom.  Either John Carter is some sort of superman that can leap the tallest building on Earth (how did the Confederacy lose the war with him on their side?) or someone is not being completely honest.


Inertia is simply resistance to change.  You learned that when you studied Newton’s Three Laws of motion.  Basically, an object at rest tends to remain at rest.  This means that if you are in space, your coffee cup will remain on that table unless you push it off.  It also means that when John Carter was laying on Barsoom, he REMAINED there!

Remember Mass?  It takes the same amount of strength to stand up on Mars as it does on Earth.  He may now weigh 74 pounds but his mass remains at 195!  Once moving, it takes less effort to keep moving but it takes the same effort to change direction or stop on Barsoom as it would on Earth.

Springing to my feet I received my first Martian surprise, for the effort, which on Earth would have brought me standing upright, carried me into the Martian air to the height of about three yards.  I alighted softly upon the ground, however, without appreciable shock or jar.  (POINT FOUR)
Add to this is acceleration of fall.  People on Earth fall at 32 feet per second per second until they reach terminal velocity of about 125 miles per hour.  The formula for this is: vf = g * t where g = gravitational acceleration which is 9.8 meters/sec/sec or 32 ft/sec/sec  and t = how many seconds you are falling until you reach terminal velocity.

On Mars, the formula remains the same but g changes to 3/7 (three-seventh) meters per second per second or 12.13 feet per second.  Which means that you are falling 2/3 SLOWER on Mars than on Earth.  So if John Carter leaps 30 feet up on Earth, he will land in about a second.  If he does that on Mars, it will take him three seconds to land, more than enough time to prepare, right himself, flex his legs, etc.   He rises just as fast (strength overcoming inertia) but his fall will take longer.  Of course, he will strike the ground just as hard since he still has that 195# of mass to deal with. It just gives him more time to scream “oh shit!” before he snaps his legs on impact.

Long jumps are the same.  He may be able to claim that he leaps 150 feet at a time, but it will take three times as long to land but the force will be the same as on Earth so he will roll bruise himself and possibly snap an ankle.  We’ll get back to that later.

So we are now at a place where he can leap higher and further than before, but each leap will take the same amount of energy as it would on Earth and so exhaust him after a few tries and he will have much more time to watch the ground come up at him. His landing will be the same as on Earth with the same bone-crunching jar.  Hardly the lack of appreciable shock he described.


Briefly, the air pressure on Mars/Barsoom is much lower than on Earth.  How little, we do not know but JC can breathe there so it must be thicker than NASA predicts.  I’m guessing maybe equal to Denver at 5000 feet.

On Earth, at sea level, Atmospheric Air pressure (atm) is about 14.7 psi, decreasing about 4% per 100’ altitude.   I say about because as the Earth spins, air at the equator is forced out further than at the poles (were Mt Everest at the equator, you could climb it easily but if at the pole, you’d not make it up a mile).   At a mile up (Denver), you have only 55% of your expected air  to breathe.  This is why it’s so difficult to breathe when you vacation in the mountains and why you tire so quickly.

Without doing any calculations, for which I do not have the data, I am going to guess and say the surface atmosphere on Barsoom where JC arrived is about equal to Denver.  Breathable if you walk around but exhausting if you exercise.  I have no way to support this other than a feeling from the books.

Which means that although John Carter could move about easily after he arrived, a few jumps and he’d be on the ground panting for air! Remember the mass and effort to move remains the same!


Ok, here is something for later chapters long after he left Thatk.

It was discovered by the Soviet Cosmonauts that lowered gravity results in bone loss!  After a lengthy stay in space, the Cosmonauts couldn’t even stand when they returned.  Basically, here is what happens in zero gravity!  (note that at 350 miles, normal orbit, gravity is 90% Earth normal. It just seems like zero because the craft is falling. Like that feeling you get when the roller coaster drops, only forever!)

 You lose between 1-2% of your bone matter per month.
 Most of this is in the lower spine and legs.
It takes twice as long to recover as it did to lose that bone.   It is unknown if you will fully recover.
Most of the lost calcium leave via the urine but enough settles in the kidneys to cause massive kidney stones.
So what does that mean?

Since Mars Gravity is 0.38% of Earth, let’s say 1/3 because I’m tired of working with decimal points, let us assume that the loss of bone on Barsoom will be ½ of in space.  So after a month on Mars, JC would loons 1/3 of one percent of his bones!  Nothing to worry about, right?  He was there 10 years!  4% per year over 10 years equals 40% bone loss!

We still don’t know if you can fully recover or if there are permanent problems.  We also don’t know how to prevent this though studies indicate that overdoing the calcium and lots of exercise MIGHT slow the loss.

If so, JC would be guzzling eggs and mantilla like milk shakes and spending two hours a day pumping iron and jogging with lead weights on his arms and legs.  Timo Manare explored this in his fanfic at Tangor’s site.  I’m going to state that as time goes on, JC looses physical and skeletal strength until he is no stronger that then average Red Man.   If so, landing after a Sak would snap legs like matches!

Where does all this leave us?

Basically, John Carter was exaggerating when he described all those fantastic leaps.  He simply could not do all that he described to Burroughs.  So here is the scenario that I calculate.

John Carter could jump higher and further than before but not as far as described.  He could do maybe 15 feet standing long jump and maybe 60 after a run.  Height to be about three feet max.  And after each jump, he’d have to rest and catch his breath until his blood built up enough iron to compensate for the reduced air.

He’d start out massively strong and impact resistant but after a few months, his bones and muscles would begin to weaken until he was no stronger than the average red man, and would therefore lose the ability to jump so far.  Also his bones would weaken and snap from a simple punch.

He’d suffer kidney stones and anemia and los of concentration from lack of air.

Eventually, he’d snap him ankles from stepping  off a stair wrong (is that why the Barsoomians use ramps?)

John Carter would have a few months of super-human abilities, just long enough to level Zodanga and rescue Dejah Thoris before he fell apart and became … normal.  Then he’d level out for the rest of his life…

Perhaps he HAD to return to Earth so when he returned in Gods of Mars, he could be another superhuman to survive Dor.

Since JC was never really on Mars, his body remained on Earth and he existed as a copy, all this discussion may very well be useless.  Perhaps he could do so much because he ‘thought’ that he could.  If so, then, like Neo in The Matrix, belief creates reality and he could be immortal and invulnerable and even fly, a real Superman, as it were, depending upon his beliefs.  Perhaps that is why he could leap 150 feet, because he never really existed in physical form and ‘believed’ that he could.

Nah, I’m more inclined to believe that he was exaggerating his abilities to entertain his favorite nephew!  He was good!  But not as  good as he claimed.

Now, where do the superhuman leaps shown in the movies come from?

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