38. Objections and responses
Does not incorporate the blur analysis of the Z-film
Perhaps the major objection to this work could be that it
takes Josiah Thompson's measurements of Kennedy's motions at face value and does
not deal with the recent claims that the blurred image in frame 313 hides the
fact that the head did not snap forward quickly at that time. Thompson has
recently supported this view, claiming that he is now convinced that his
original measurements were wrong. He based his conclusions on "A Motion
Blur Analysis of the Zapruder Film" by David Wimp, which appears at the
time of this writing on Ron Hepler's web site (http://server3002.freeyellow.com/rhepler).
There are several reasons why this view is incorrect. It is
also largely irrelevant to the calculations presented here. The first reason why
it is wrong is the simplest—you can see clearly that the head did indeed snap
forward. You can even see the angle of the back of Kennedy's head shift to the
right. To the extent that frame 313 is blurred, it will mean that the head
snapped even farther forward than the frame appears to show (and as confirmed by
the calculations). The second reason is that the head had to snap
forward—neutron activation analysis (NAA) of the fragments in the brain
matches them to the large fragment in the front seat, and ballistics traces this
fragment to Oswald's rifle. As shown in great detail in earlier sections here,
the forward speed of the snap and the distance traveled can be easily estimated
from the mass of the bullet and its entrance and exit velocities, and they are
completely consistent with the measurements. If anything, they exceed the
measurements. It all fits into a coherent picture that cannot be denied.
Most importantly, however, the motions around frame 313 do
not have to be known precisely because the calculations of the lurch essentially
skip over them—they predict the velocity of the lurch after the snap is
finished and do not use the values of the snap in that calculation. A clear
speed of -0.8 ft s-1 can be seen in 314–315, quite independent of
anything that happened in 312–314. So the conclusions of this work remain
valid no matter what one thinks of the snap's existence or nonexistence.
Expanded discussion of the noneffect of blurring
Assumes that the Z-film is genuine
Obviously, this work assumes that the Zapruder film is
genuine. It is ludicrous to think that it is anything else. Thompson has
effectively destroyed the myth of alteration in a
brilliant essay that is posted here.
Accepts the NAA uncritically
This monograph accepts the neutron activation data on the
lead fragments only after the
exhaustive analysis that appears elsewhere on this web site.
Accepts the other physical evidence uncritically
The basic physical evidence in this case is not accepted
uncritically. On the contrary, it has been examined carefully and repeatedly and
found to be self-consistent
and multiply redundant. The simple, direct picture provided by this evidence
has been challenged many times, but never successfully, nor has an alternate
picture ever been successfully provided.
Does not provide a standard for accepting or rejecting physical evidence
It is true that this monograph does not provide a codified
procedure for validating physical evidence. Instead, it validates by example. I
hope to formalize these procedures in the near future.
Low mass of head
There may be a conflict between the lighter heads that these
calculations support (5–7 lb) and the classical heads that are usually quoted
(more like 10 lb, or even 15). Does this mean there is something wrong with
these calculations? Not necessarily, although the difference remains unresolved
at the time of this writing (late February 2003). Since the constraints on the
head come from speeds of the snap (Section 25),
one might expect that the values for the lurch derived from scenarios 6 and 7,
which incorporate the snap, would differ from the earlier scenarios, which did
not. But this is not the case—both the linear and angular versions of scenario
6 give the same answers as the corresponding scenarios 3–5 (all of which use
the same default values and solve for vlurch and vcloud).
It appears, for reasons unknown, that the effective mhead is
really 5–7 lb, and maybe 8 as well.
Circular reasoning
One could suggest that the entire procedure used here of
solving the two simultaneous equations contains a built-in circularity in that
the answer will balance only the components that one includes, and thereby give
an artificial sense of closure. But this is not quite true. All reasonable
components were included, even a second bullet. The answers showed that the
system could not be properly balanced under certain conditions.
Exploding bullet
Tony Marsh has suggested on the newsgroup
alt.conspiracy.jfk that it would be helpful to consider how an exploding bullet
(such as claimed by James Files) would affect these calculations and
conclusions. He noted that "when Velex was producing them, they found that the energy
deposited was about double the standard bullet." At first glance, one might
think that an exploding bullet would wreck the calculations because there would
be no way to know how much energy was deposited or how its fragments flew out.
But further reflection shows that the picture is not this bad, and probably is
tractable, because the Zapruder record shows what happened, whether the head exploded from a
normal bullet or from an exploding one. The effects of either kind of bullet are
built into the cloud and large fragments that we see in the film and can
understand with physics. Thus it becomes more a question of naming the cause (exploding
bullet or regular bullet) than of dealing with it. The analysis here stands.
Furthermore, there were no physical traces of an exploding
bullet, either physically or chemically. Without them we are not allowed to
invoke one.
Ahead to Future Work
Back to Unification of the Physical Evidence
Back to Physics of the Head Shot