Would A Bullet Really Knock You Backwards? DEBUNKED

[Andrew Mason]

Correct.

Correct. The initial movement, during the z312-z313 interval, is consistent with a WCC/MC bullet striking from behind.

Yes and no. In theory, the "Jet Effect" could cause a 'target' to move back toward the rifle. This has been demonstrated with various targets like taped melons.

But this did not happen in the JFK murder. Because the head initially moved forward. If the "Jet Effect" occurred, JFK's head would have started moving backwards almost immediately, within 5 to 10 milliseconds of the bullet impact, because there would be no big 55 millisecond delay in the head being struck and organic material starting to move forward. We can see in frame z313 that the organic material had already started moving, right about the time the shutter closed on z312. A piece of bone, likely the 'Harper fragment', is already two to four feet away from the head in z313.

The forward bullet momentum is imparted to the head before the head explodes so the head is driven forward before it is driven backward.  One has to take into account that the rearward momentum imparted by the exploding matter from the head first had to stop the head from going forward.  It is already accelerating rearward in z313.

The "Jet Effect" can occur. But in all cases, it is immediate. A taped melon doesn't move two inches away from the shooter, and then reverse directions, like seen with JFK.

A melon is not a good model for a human skull.  The bullet does not impart much forward momentum to the melon in penetrating the melon. Also the melon is not free to move forward.  A melon sitting on a wet level ice surface with hard bone strapped to it for the bullet to pass through on entry would provide a better model.

[Dan O'meara]

?? How is "jet-effect" not "good old-fashioned physics"? It is just conservation of momentum. Alvarez did not go beyond Newton's laws in explaining it.

In his calculations, Alvarez omitted the most significant force acting on JFK's head at the time - the initial impact of the bullet on the back of the skull. The omission of this most fundamental force in his calculations renders his results invalid.

Wecht and Aguilar point out the following in an article entitled, "NOVA’s Cold Case: JFK - the Junk Science Behind PBS’s Recent Foray into the Crime of the Century", from 2016

Josiah Thompson, Ph.D. recently got the photo file of Alvarez’s shooting tests from a former Berkeley grad student who had participated in the tests, Paul Hoch, Ph.D. When he reviewed the images, Thompson discovered, as we describe, that the Nobel Laureate had misrepresented his own results: virtually all the objects he fired at flew away from the shooter, not toward him, except for the ones he reported in the AJP. Alvarez not only neglected to mention his inconvenient results, in the AJP he clearly implied there were none. (Paul Hoch never told anyone about his former professor’s contradictory results, despite having been asked about the tests for decades.)

The deliberate omission of these results renders his whole theory, as a scientific examination, invalid

Another problem for the Jet Effect theory is that the Z-film actually did record a couple of "jets" of material exiting the top of JFK's head at the moment of the head-shot. The problem is that these jets were not travelling in a direction that would have thrown JFK's head back and to the left.
In the Z-frame below I have picked out these two "jets" of material with arrows:



In the frame below, the yellow line represents the line running through the top of his head. This is my own rough estimation and is made to give a general idea of the direction of the "Jets" (marked in red).



Any Jet Effect would push JFK's head downwards rather than backwards.

[Dan O'meara]

Well, good, I finally have someone to talk over 'old-fashioned physics' with.

How to you explain the motion of JFK's head, during z312-z318. This motion is detailed in Josiah Thompson's book "Six Seconds in Dallas", not by Josiah Thompson but by Physics graduate student William Hoffman. In Hoffman's data:

from z312-z313: The head moves forward at 2 mph.
from z313-z318: The head starts to move backwards, gradually moving faster and faster, reaching a maximum speed of 1.9 mph at z318.

How does a frontal shot explain this?
Why would it cause an initial movement of the head forward?
And when the backward movement starts, why does the speed gradually accelerated? Why wouldn't the bullet passing through the head transfer all it's momentum with 1 to 2 milliseconds, but instead transfer it's momentum over the course of 200 milliseconds?

By the way, the acceleration of the limousine does not explain this. William Hoffman, back in 1966, was way ahead of everyone. He also plotted the speed of the limousine and the acceleration of the limousine is not even a tenth of the amount of accelerated needed to explain the backwards movement of JFK's head.

 * * * * *

Also, it is not proper science, when looking into a problem to declare some theories are 'unnecessary contrivances' and should not be considered. "The theory of Continental Drift is an unnecessary contrivance, and must not be considered a possible explanation for why an animal specie from the distance past appears to have been on both sides of the Atlantic, now separated by thousands of miles".

And so it is not proper science, when looking into a problem to declare:

1. A shot from the front, is an unnecessary contrivance to explain the movement of JFK's head.
2. The 'Jet Effect', is an unnecessary contrivance to explain the movement of JFK's head.
3. The 'Neurological Spam', is an unnecessary contrivance to explain the movement of JFK's head.

All three theories must be considered. And since only the "Neurological Spam' theory explains the movement of JFK's head, it is the theory that should be accepted as the one most probably true. Unless future data collected requires a reassessment". Like video of a taped melon reversing direction. Or video of a bullet striking a target and causing the target to gradually accelerate over the course of 200 milliseconds, or a fifth of a second. But until such a time, the "Neurological Spam' theory is the one I am going to go with.

Also, it is not proper science, when looking into a problem to declare some theories are 'unnecessary contrivances' and should not be considered.

Hi Joe, I'm certainly not suggesting these things shouldn't be considered and I accept the term "contrivance" might appear a little harsh. What I meant by this was that when the "back and to the left" movement came into the public sphere there was a need, for those who were putting forward a shot from behind, to come up with an explanation for how a shot from behind could cause such a movement.
It seemed very intuitive to accept that such a movement could only have been caused by a shot from the right front, which screamed CONSPIRACY, and an answer needed to be found quickly.
"Neurological spasm" and the "Jet Effect" were born out of this need for an explanation.

How to you explain the motion of JFK's head, during z312-z318. This motion is detailed in Josiah Thompson's book "Six Seconds in Dallas", not by Josiah Thompson but by Physics graduate student William Hoffman. In Hoffman's data:

from z312-z313: The head moves forward at 2 mph.
from z313-z318: The head starts to move backwards, gradually moving faster and faster, reaching a maximum speed of 1.9 mph at z318.

How does a frontal shot explain this?
Why would it cause an initial movement of the head forward?
And when the backward movement starts, why does the speed gradually accelerated? Why wouldn't the bullet passing through the head transfer all it's momentum with 1 to 2 milliseconds, but instead transfer it's momentum over the course of 200 milliseconds?

How does a frontal shot explain this?
It doesn't.

Why would it cause an initial movement of the head forward?
It wouldn't

In my opinion, the backwards head movement isn't caused by a bullet from the front passing through his head.

1. A shot from the front, is an unnecessary contrivance to explain the movement of JFK's head.
2. The 'Jet Effect', is an unnecessary contrivance to explain the movement of JFK's head.
3. The 'Neurological Spam', is an unnecessary contrivance to explain the movement of JFK's head.

All three theories must be considered. And since only the "Neurological Spam' theory explains the movement of JFK's head, it is the theory that should be accepted as the one most probably true.

It is only "probably true" if these are the only possible options.

[Andrew Mason]

In his calculations, Alvarez omitted the most significant force acting on JFK's head at the time - the initial impact of the bullet on the back of the skull. The omission of this most fundamental force in his calculations renders his results invalid.

Alvarez did NOT ignore the impact of the bullet. He showed that the momentum ejected matter can exceed the momentum of the incoming bullet and drive the head backward (from his article: 44 Am. J. Phys. Vol 814, at page 819):

• I concluded that the retrograde motion of the President's head, in response to the rifle bullet shot, is consistent with the law of conservation of momentum, if one pays attention to the law of conservation of energy as well, and includes the momentum of all the material in the problem. The simplest way to see where I differ from most of the critics is to note that they treat the problem as though it involved only two interacting masses: the bullet and the head. My analysis involves three interacting masses, the bullet, the jet of brain matter observable in frame 313, and the remaining part of the head. It will turn out that the jet can carry forward more momentum than was brought in by the bullet, and the head recoils backward, as a rocket recoils when its jet fuel is ejected.

Wecht and Aguilar point out the following in an article entitled, "NOVA’s Cold Case: JFK - the Junk Science Behind PBS’s Recent Foray into the Crime of the Century", from 2016

Josiah Thompson, Ph.D. recently got the photo file of Alvarez’s shooting tests from a former Berkeley grad student who had participated in the tests, Paul Hoch, Ph.D. When he reviewed the images, Thompson discovered, as we describe, that the Nobel Laureate had misrepresented his own results: virtually all the objects he fired at flew away from the shooter, not toward him, except for the ones he reported in the AJP. Alvarez not only neglected to mention his inconvenient results, in the AJP he clearly implied there were none. (Paul Hoch never told anyone about his former professor’s contradictory results, despite having been asked about the tests for decades.)

The deliberate omission of these results renders his whole theory, as a scientific examination, invalid

It is important to use something that resembles a human skull.  The skull does two things that cause the jet effect that a melon cannot do: 1. the hard bone of the back of the skull flattens the bullet on entry so that it pushes material in its path in passing through the soft interior part of the skull and 2. the skull is a rigid enclosure for the brain so the pressure builds up in the skull as the bullet passes through.  The melon does not replicate the skull.

The jet effect is real. The best demonstration of the jet effect was done several years ago by Chad Zimmerman. Chad fired a 6.5 mm jacketed WC bullet from his Mannlicher-Carcano rifle into a suspended turkey. He strapped pork ribs to the entry side of the turkey (the left side) to simulate the skull bone.

Now, it was a big turkey much heavier than a human head and it did not move forward noticeably from the impact of the bullet, possibly due to the mass of the turkey and due to the shot being off-centre causing rotation of the turkey.  But the rearward motion, due to the massive explosion of matter, is rapid and obvious. I have taken his video frames and slowed down the first 4 frames (2 sec. per frame) and the final frames at .5 seconds per frame so you can see the direction that the turkey moves from the explosive ejection of matter:


The original video is here:

http://dufourlaw.com/JFK/turkeyribshot1a.mpg

Another problem for the Jet Effect theory is that the Z-film actually did record a couple of "jets" of material exiting the top of JFK's head at the moment of the head-shot. The problem is that these jets were not travelling in a direction that would have thrown JFK's head back and to the left.
In the Z-frame below I have picked out these two "jets" of material with arrows:



In the frame below, the yellow line represents the line running through the top of his head. This is my own rough estimation and is made to give a general idea of the direction of the "Jets" (marked in red).



Any Jet Effect would push JFK's head downwards rather than backwards.

That is not a problem at all. The leftward-rearward momentum imparted to the head is equal and opposite to the rightward/forward component of momentum of the ejected matter. Almost all of that matter goes forward and it exits outward from the right side of his head.  The only matter that does not impart a rearward/leftward impulse to the head is matter travelling at right angles to the rearward/leftward direction.  A body ejected with momentum p at a direction 45 degrees to horizontal imparts a horizontal component of momentum equal to .707p (cosine of 45 degrees). 

[Joe Elliott]

The forward bullet momentum is imparted to the head before the head explodes so the head is driven forward before it is driven backward.  One has to take into account that the rearward momentum imparted by the exploding matter from the head first had to stop the head from going forward.  It is already accelerating rearward in z313.

There are two problems I have.

One. As I understand it, the Law on the Conservation of Momentum is an absolute law. It must be adhered to millisecond to millisecond. Instant to instant. It's not like a checking account with overdraft protection. It can never be, even temporarily, even for just 55 millisecond, or 1 millisecond, "Out of balance".

Two. During z312-z313, there was (according to you, if I understand you correctly) the momentum of:

1. The head moving forward.
2. The forward momentum of the bullet fragments, which all three fragments together still have about half the momentum of the pristine bullet.
3. The forward momentum of organic material flying forward which we can see in z313.

You seem to imply that this would put the momentum out of balance. And it would take time for the head to stop it's forward movement and start moving backwards. Only after the head started moving backwards, would the overall momentum of the head, bullet fragments and organic material get back in balance, that is be equal to the momentum of the pristine bullet.

My 'High School' understanding of Classical Newtonian Physics (my knowledge of Physics only comes from a course in high school from an excellent teacher) is that this is in error. Conservation of Momentum must be maintained millisecond to millisecond. Instant to Instant. It can never be temporarily out of balance. And so "It takes time for the forward motion to slow down and stop", "It takes time for the backwards momentum to reverse" cannot be true.

If the 'Jet Effect' is true, JFK's head would have moved forward, at most, about 0.4 inches (1 cm) during the first 10 mm, the longest Dr. Ken Rahn thought the explosion of the head could be delayed. At that point, the head would explode and organic material would be moving forward. Requiring the head to start moving backwards, immediately. But instead of seeing this, frames z312 and z313 shows that the head moved forward a full 2 inches (5 cm). Consistent with the organic material having a small amount of forward momentum (it clearly had some) but not enough to reverse the direction of movement or to even slow down the forward movement very much. Only when the muscles of JFK's body started to contract would this backwards movement of the head start.

Note: Regardless of how long Dr. Ken Rahn thought the head explosion could be delayed, z313 shows the head explosion occurred very early. The 'Harper fragment' being seen as a series of 'dots' two to four feet from JFK's head shows the head exploded very early on, just after the shutter closed on z312. The head should have been moving backwards at the time the shutter opened for z313 if the 'Jet Effect' was true.

A melon is not a good model for a human skull.  The bullet does not impart much forward momentum to the melon in penetrating the melon. Also the melon is not free to move forward.  A melon sitting on a wet level ice surface with hard bone strapped to it for the bullet to pass through on entry would provide a better model.

Then I would like to see a film of a better model of a human head being shot, moving forward two inches, and then reversing direction starting 55 milliseconds after the bullet strikes. Some good experiment that can lead me into believing the 'Jet Effect' theory might be true in the case of the JFK assassination.

[Mitch Todd]

The video posted in the OP has no bearing on JFK's head-shot.
JFK's head explodes as a result of the shot. Pieces of his skull are blown in various directions. Jets of material, possibly brain matter and skull, are seen emanating from the top of his head. The top of his head literally blows off as a result of the shot.
To imagine there is no significant transfer of momentum from the bullet to the head in this instance is ludicrous.
The force required to achieve this incredible amount of damage would surely be reflected in how JFK's head moves as a result of this impact.

Neurological spasm and the jet effect are unnecessary contrivances when coming to explain the "back and to the left" movement of JFK as a result of the head-shot.
Good, old-fashioned physics is more than sufficient.

Good, old-fashioned physics is more than sufficient.

The jet-effect thingy is quite the good ol' physics that great grandpa had to beat out of rocks with other rocks back in the day. It's the kind of simple conservation of momentum problem handled in first semester freshman classical mechanics classes.

[Mitch Todd]

There are two problems I have.

One. As I understand it, the Law on the Conservation of Momentum is an absolute law. It must be adhered to millisecond to millisecond. Instant to instant. It's not like a checking account with overdraft protection. It can never be, even temporarily, even for just 55 millisecond, or 1 millisecond, "Out of balance".

Two. During z312-z313, there was (according to you, if I understand you correctly) the momentum of:

1. The head moving forward.
2. The forward momentum of the bullet fragments, which all three fragments together still have about half the momentum of the pristine bullet.
3. The forward momentum of organic material flying forward which we can see in z313.

You seem to imply that this would put the momentum out of balance. And it would take time for the head to stop it's forward movement and start moving backwards. Only after the head started moving backwards, would the overall momentum of the head, bullet fragments and organic material get back in balance, that is be equal to the momentum of the pristine bullet.

My 'High School' understanding of Classical Newtonian Physics (my knowledge of Physics only comes from a course in high school from an excellent teacher) is that this is in error. Conservation of Momentum must be maintained millisecond to millisecond. Instant to Instant. It can never be temporarily out of balance. And so "It takes time for the forward motion to slow down and stop", "It takes time for the backwards momentum to reverse" cannot be true.

If the 'Jet Effect' is true, JFK's head would have moved forward, at most, about 0.4 inches (1 cm) during the first 10 mm, the longest Dr. Ken Rahn thought the explosion of the head could be delayed. At that point, the head would explode and organic material would be moving forward. Requiring the head to start moving backwards, immediately. But instead of seeing this, frames z312 and z313 shows that the head moved forward a full 2 inches (5 cm). Consistent with the organic material having a small amount of forward momentum (it clearly had some) but not enough to reverse the direction of movement or to even slow down the forward movement very much. Only when the muscles of JFK's body started to contract would this backwards movement of the head start.

Note: Regardless of how long Dr. Ken Rahn thought the head explosion could be delayed, z313 shows the head explosion occurred very early. The 'Harper fragment' being seen as a series of 'dots' two to four feet from JFK's head shows the head exploded very early on, just after the shutter closed on z312. The head should have been moving backwards at the time the shutter opened for z313 if the 'Jet Effect' was true.

Then I would like to see a film of a better model of a human head being shot, moving forward two inches, and then reversing direction starting 55 milliseconds after the bullet strikes. Some good experiment that can lead me into believing the 'Jet Effect' theory might be true in the case of the JFK assassination.

Actually, Joe, you are exactly correct about the jet effect's inapplicability in this case, and for the reasons you've mentioned.

There are two issues that never get mentioned on the subject of JFK's movement post-312.

First is gravity. That may seem like a ridiculous thing to bring up, but it's an ever-present force. One of considerable magnitude. A number of witnesses described JFK as "slumping" to his left. The Muchmore and Bronson films show that JFK was leaning well over to his left at the time he was hit in the head. Just considering gravity, the left part of "back and to the left" makes perfect sense.

The second comes in the form of Jacqueline Kennedy, who is holding on to JFKs left arm at 312. She's also moving her head forward around his elbow, as if the left arm is in her way and she's trying to see her husband's face. Given that she's already got a grip on his arm, it's a natural expectation that she would be pulling his elbow back to facilitate her view. So that when bullet struck and the lights went out, JFK would have been pulled by his wife back and to the left.

Tying these two together, if you look carefully at the z-film, you can see where JFK starts to shift to the left. It starts just after frame 255. Maybe this is just a coincidence, but Jackie grabs JFK's upper arm with her right hand at z245 and his left elbow with her left hand at z255. JFK's movement after the last shot may simply be the result of his wife trying to pull her towards him.

It's obvious once you look, but I never see this get brought up.

[Joe Elliott]

Actually, Joe, you are exactly correct about the jet effect's inapplicability in this case, and for the reasons you've mentioned.

There are two issues that never get mentioned on the subject of JFK's movement post-312.

First is gravity. That may seem like a ridiculous thing to bring up, but it's an ever-present force. One of considerable magnitude. A number of witnesses described JFK as "slumping" to his left. The Muchmore and Bronson films show that JFK was leaning well over to his left at the time he was hit in the head. Just considering gravity, the left part of "back and to the left" makes perfect sense.

The second comes in the form of Jacqueline Kennedy, who is holding on to JFKs left arm at 312. She's also moving her head forward around his elbow, as if the left arm is in her way and she's trying to see her husband's face. Given that she's already got a grip on his arm, it's a natural expectation that she would be pulling his elbow back to facilitate her view. So that when bullet struck and the lights went out, JFK would have been pulled by his wife back and to the left.

Tying these two together, if you look carefully at the z-film, you can see where JFK starts to shift to the left. It starts just after frame 255. Maybe this is just a coincidence, but Jackie grabs JFK's upper arm with her right hand at z245 and his left elbow with her left hand at z255. JFK's movement after the last shot may simply be the result of his wife trying to pull her towards him.

It's obvious once you look, but I never see this get brought up.

Mitch

I agree. I think JFK was leaning to the left. It appears Jackie was pushing Jack's left elbow down, to get a better view of his face to see what was the matter. With his arms being fairly rigid due to the neck wound, that would rotate the torso some to the left.

We don't know how Jackie affected JFK's movement during z312-z318.

JFK was sitting pretty upright. So gravity wouldn't have had much of an effect, at least before z317. Before z317, the acceleration of JFK's head was up to 0.25 G's. JFK would have to be tilted back by around 15 degrees to get that amount of acceleration ( 1 G * sin(15) ). I don't think he was tilted back nearly that much. If anything, he was leaning forward some at z312. JFK's backwards acceleration was not caused by gravity. Nor by the way too small acceleration of the limousine during that time, that was practically moving at a steady speed.

But we know that not all of JFK's post z312 movement was caused by Jackie. At z-316 through z-318, JFK's right elbow suddenly j-e-r-k-s up 6 inches, than falls limply down. That is clearly caused by a neurological spasm.