“Back
and to the Left”: The Zapruder Film
The
most striking moment of the Zapruder film arrives at frame 313 when
President Kennedy's head explodes and his entire upper body is
slammed violently backwards and leftwards. Although I don't believe
it's accurate to say, as Reitzes does, that the “head snap” has
been held up by critics as “irrefutable proof
of
conspiracy”, there is no doubt that to the majority of us laymen it
certainly gives the immediate impression that the fatal shot came
from the right front. In fact, after Zapruder's home movie was shown
on television for the first time in 1975, public outrage was so great
that it ultimately resulted in the formation of the House Select
Committee on Assassinations.
But as Reitzes is quick to point out, numerous medical experts convened by government panels have consistently reassured the American public that “back and to the left” doesn't prove anything. He quotes experts for the Rockefeller Commission in 1975 who were “unanimous in finding that the violent backward and leftward motion of the President's upper body following the head shot was not caused by the impact of a bullet coming from the right front.” One of these specialists, Dr. Alfred Olivier—who had previously worked as the chief ballistics expert for the Warren Commission—claimed, unsurprisingly, that the President's movement “could not possibly” be the result of a frontal shot and “attributed the popular misconception to the dramatic effects employed in” movies and television.
However, the government's experts failed to provide evidence to support their assertions. Even in the 1970s, films showing victims of rifle shots to the head were readily available. I myself have seen old black and white wartime films of kneeling prisoners being shot in the back of the head with bolt action rifles. In each case, the victims did not lurch drastically back towards the shooter but fell forwards onto their faces. Regardless, the Rockefeller experts chose not to provide documented examples to buttress their position and instead offered two theories, the “neuromuscular reaction” and the “jet effect”, neither of which has withstood scrutiny.
The
“jet effect” suggests, that in a similar fashion to the thrust
developed in a rocket or jet engine in response to its exhaust, the
explosive exiting of blood and brain matter from the right side of
Kennedy's head created a corresponding propulsive momentum in the
opposite direction. The theory was the brainchild of Nobel
Prize-winning physicist and stern Warren Commission supporter, Dr.
Luis Alvarez, who—though
he kept the fact to himself—was
paid by the government to conduct his study. (David Wrone, The
Zapruder Film: Reframing JFK's Assassination,
p. 103) Alvarez demonstrated the effect by shooting a high powered
rifle at melons resting on fence posts which caused the melons to
recoil back towards the shooter. But as scientist Dr. Donald Thomas
explained in his fine book, Hear
No Evil: Social Constructivism & the Forensic Evidence in the
Kennedy Assassination,
Alverez had rigged the tests.
Firstly,
the melon is not, as Dr. Alvarez claimed, a “reasonable facsimile
of a human head.” In fact, as Dr. Thomas writes, “a melon differs
from a human head in precisely those characteristics that make the
jet effect implausible in the latter, but possible in the former.”
(Thomas, p. 359) A melon weighs approximately half as much as a human
head and so requires less energy to set in motion. It also lacks a
bone which means that it offers little resistance to a bullet so that
there is little deposition of momentum and, consequently, very little
force to overcome. “By minimizing the deposition of momentum, using
a target with little resistance,” Dr. Thomas writes, “Alvarez was
free to work on the other end of the equation, by jacking up the
velocity.” Dr. Alvarez used a high-powered 30.06 rifle instead of
the lower velocity Mannlicher Carcano and hot-loaded his cartridges
to 3000 feet per second. (Ibid) When another Warren Commission
defender, Dr. John Lattimer, attempted to duplicate Alvarez's tests
using an actual Mannlicher Carcano and factory ammunition, he did not
achieve the jet effect. His melons simply fell off the pedestal;
sometimes backwards and sometimes forwards. (Ibid, p. 362)
Dr.
Thomas also makes the point that in order for the jet effect to be a
viable explanation for the backward motion, the exit wound, or the
“vent”, would have to have been in the very front of the skull.
But the massive wound to Kennedy's skull involved most of the right
side, from the temple back to the occiput. And if the vent was on the
right side, “then the jet effect would have driven the head to the
left (the side opposite the vent) not backwards.” (Ibid, p. 358) As
Dr. Thomas summarizes, “...the President did not have an exit wound
in a position that would have caused his head to move rearward if
there was a jet effect.” (Ibid, p. 370)
As
it's explanation for the backwards motion, the HSCA favoured the
neuromuscular reaction—a
theory that was put to the committee by ballistics expert, Larry
Sturdivan, who had worked at Edgewood Arsenal under Dr. Alfred
Oliver. Sturdivan put his hypothesis in the simplest possible terms
for last year's Cold
Case: JFK
television special:
“The
tissue inside the skull was being moved around. It caused a massive
amount of nerve stimulation to go down his spine. Every nerve in his
body was stimulated. Now, since the back muscles are stronger than
the abdominal muscles, that meant that Kennedy arched dramatically
backwards."
But
as Dr. Thomas explains, "Sturdivan's postulate suffers from a
patently anomalous notion of the anatomy. In any normal person the
antagonistic muscles of the limbs are balanced, and regardless of the
relative size of the muscles, the musculature is arranged to move the
limbs upward, outward, and forward. Backward extension of the limbs
is unnatural and awkward; certainly not reflexive. Likewise, the
largest muscle in the back, the 'erector spinae', functions exactly
as its name implies, keeping the spinal column straight and upright.
Neither the erector spinae, or any other muscles in the back are
capable of causing a backward lunge of the body by their
contraction." (Thomas, p. 341) Additionally, the type of
reaction Sturdivan posits is simply not in keeping with what we see
on the Zapruder film. Kennedy's movement did not begin with an
arching of the back. As the
ITEK corporation noted following extensive slow motion study of the
Zapruder film, his head snapped backwards first, “then his whole
body followed the backward movement.” (ITEK report, p. 64)
Reitzes
writes that immediately before the backward motion appears on the
Zapruder film, Kennedy's head moves forward by 2.3 inches. This, he
suggests, is the “instant of impact” of a bullet entering the
back of the head. This alleged forward motion was first reported by
Josiah Thompson in his book, Six
Seconds in Dallas, but
Thompson has since changed his mind about its very existence. In
his online article, Bedrock
Evidence in the Kennedy Assassination,
Thompson writes: “In the years since those measurements were made,
I've learned I was wrong. Z312 is a clear frame while Z313 is smeared
along a horizontal axis by the movement of Zapruder's camera. The
white streak of curb against which Kennedy's head was measured is
also smeared horizontally and this gives rise to an illusory movement
of the head. Art Snyder of the Stanford Linear Accelerator staff
persuaded me several years ago that I had measured not the movement
of Kennedy's head but the smear in frame 313. The two-inch forward
movement was just not there.”
On
the other hand court certified Crime Scene Investigator, Sherry
Fiester, believes Thompson's initial observations were correct. She
characterizes the alleged forward motion as a "movement into the
force" of a shot from the front. Citing a number of ballistics
studies, Fiester explains, "Once a bullet enters the skull...the
bullet immediately loses velocity. The loss of velocity results in a
transfer of kinetic energy...This initial transfer of energy causes
the target to swell or move minutely into the force and against the
line of fire." (Fiester, Enemy
of the Truth: Myths, Forensics, and the Kennedy Assassination,
p. 245)
The
reader will have to do their own research and decide for themselves
whether Thompson or Fiester is correct but there is something else
that needs to be considered. That is, the motions of the other
occupants of the Presidential limousine who, the Zapruder film shows,
all moved forward at the time of the head shot and continued their
forward motion after Kennedy's body was sent hurtling backwards. This
is clearly demonstrated in the these two animations from researcher
David Wimp:
It
stands to reason that these people, who all made the same motion,
were all affected by the same force. That force would appear to have
been the deceleration of the limousine. If Dr. Alvarez's calculations
are correct, then it appears that the President's car began to slow
down a little under one second before the head shot at approximately
Zapruder frame 300. (Thomas, p. 340) This was apparently the result
of Secret Service driver Willaim Greer touching the brakes—an
inexplicable act that caused many bystanders to believe that the
limousine came to a virtual standstill during the assassination.
So,
if Greer tapping the brake caused the other limo passengers to lurch
forward, then it quite probably was responsible for any forward
motion on the President's part. There is, then, no compelling reason
to accept Reitzes' hypothesis that Zapruder frames 312 to 313
captured the “instant of impact” of a shot from the rear.
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