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Since this TNG episode is frequently cited as support for the notion of personal shields against physical attack for Trek soldiers, let's look at it.

During yet another holodeck crisis, Worf built a device using his communicator (and possibly Troi's, too) that deflected bullets from simulated 19th century handguns.

Problem. Those impacts didn't even budge Worf, while the transfer of momentum from actual bullets certainly would have, shield or no shield.

Possiblities:

1) Worf's device somehow tapped into the ship's forcefield systems (shown to be capable of generating forcefields in arbitrary locations in "Allegiance"). A forcefield generated by the ship would have the ship's momentum to keep it from being moved by the bullets.

2) The bullets carried no momentum. This would mean that they were massless forcefield constructs, and Worf's device would only need to mess with the holodeck's ability to create and direct such forcefields.

Either way, I think the lack of any momentum transfer negates this incident as proof that the Federation can make small forcefield generators capable of deflecting bullets.

I( thought all the holograms were on ST were forcefields that emit photons anyway? If so...couldn't worf's personnel shield simply cancel out the holographic bullet?

Hmmm. But then the holographic bullets in ST:FC certainly carried momentum. Just ask the Drone formerly known as Ensign Lynch.

http://www.stardestroyer.net/Empire/HateMail/Lynch.jpg

Rye wrote:I( thought all the holograms were on ST were forcefields that emit photons anyway? If so...couldn't worf's personnel shield simply cancel out the holographic bullet?

Basically a variation on Option 2. Unless I'm mistaken, though, you can actually see ricochet's in the televised episode, so the bullets aren't just negated; they have to be deflected somehow.

We know that holodecks replicate some of the materials found in them, so it's a common assumption that when the holodeck safeties fail, dangerous items are replicated instead of simulated. If the handguns were replicated, then the bullets would have mass and momentum.

Hmm, funny how the Borg couldn't do it.

Ted C wrote:

Rye wrote:I( thought all the holograms were on ST were forcefields that emit photons anyway? If so...couldn't worf's personnel shield simply cancel out the holographic bullet?

Basically a variation on Option 2. Unless I'm mistaken, though, you can actually see ricochet's in the televised episode, so the bullets aren't just negated; they have to be deflected somehow.

We know that holodecks replicate some of the materials found in them, so it's a common assumption that when the holodeck safeties fail, dangerous items are replicated instead of simulated. If the handguns were replicated, then the bullets would have mass and momentum.

Ah right, i didn't know that.

ONly thing i can think of is that Worf's device changed the programming of the incoming bullets...

Ted C wrote:Unless I'm mistaken, though, you can actually see ricochet's in the televised episode, so the bullets aren't just negated; they have to be deflected somehow.

That could just be another holodeck illusion making it "look" real and not actual ricochet.

Darth Servo wrote:Hmmm. But then the holographic bullets in ST:FC certainly carried momentum. Just ask the Drone formerly known as Ensign Lynch.

http://www.stardestroyer.net/Empire/HateMail/Lynch.jpg

If the bullets were actually some type of shaped electromagnetic force field, they could apply force to the drone without having mass and momentum. Conservation of momentum would be achieved by balancing the momentum transferred to the drone with equal and opposite momentum in the ship itself (since the holodeck emitters are firmly anchored to the ship's structure).

Due to the dramatic mass difference, the change in the ship's momentum would be unnoticeable (just as it is when people exert force against the deck to walk).

Let's not forget how many Trek Trechnologies somehow cancel momentum, a great example is Wesley's force-field/tractor beam device in the third episode, The Naked Now. Probably related to subspace like everything else.

The Silence and I wrote:Let's not forget how many Trek Trechnologies somehow cancel momentum, a great example is Wesley's force-field/tractor beam device in the third episode, The Naked Now. Probably related to subspace like everything else.

Simply look for how the mysterious technology is somehow anchored to something with high mass/momentum. In the case of Wesley's little tractor/repulsor, I would conclude that the field he created is somehow anchored to the doorframe.

I like the original script for this episode better then the one that aired.

In the original script, instead of useing a forcefield to deflect the bullets, Worf allows himself to be shot. He takes all five or six bullets, and still maganges to defeat the holo-Data by ripping its head off.

I guess they thought that would have been to violent for TV.

In this episode, the safeties were turned on but they were not functioning properly. In STFC, the safeties were explicitly turned off. Why should it be so surprising that the effects of the bullets are different?

Ted C wrote: Simply look for how the mysterious technology is somehow anchored to something with high mass/momentum. In the case of Wesley's little tractor/repulsor, I would conclude that the field he created is somehow anchored to the doorframe.

Haven't you just disproven what you said in your original post?

In the case of Worf's shield, you could conclude that the field he created is somehow anchored to the floor.

Lord Edam wrote:

Ted C wrote: Simply look for how the mysterious technology is somehow anchored to something with high mass/momentum. In the case of Wesley's little tractor/repulsor, I would conclude that the field he created is somehow anchored to the doorframe.

Haven't you just disproven what you said in your original post?

In the case of Worf's shield, you could conclude that the field he created is somehow anchored to the floor.

List that as option 3, if you want. The floor wouldn't make a good brace for the elliptical bubble we saw around Worf, though (unlike the door frame, which would make an excellent brace for the flat shield Wesley created).

Ted C wrote:List that as option 3, if you want. The floor wouldn't make a good brace for the elliptical bubble we saw around Worf, though (unlike the door frame, which would make an excellent brace for the flat shield Wesley created).

It would be as good as whatever was acting as the brace when Wesley was flying chairs around with the exact same device as later became a repulsor in a doorway.

Lord Edam wrote:

Ted C wrote:List that as option 3, if you want. The floor wouldn't make a good brace for the elliptical bubble we saw around Worf, though (unlike the door frame, which would make an excellent brace for the flat shield Wesley created).

It would be as good as whatever was acting as the brace when Wesley was flying chairs around with the exact same device as later became a repulsor in a doorway.

That thing could easily be anchoring itself to the desktop; an explanation which has been pointed out many times before. It's not as if a chair weighs as much as a man.

Oh wait, you're trying to prove the conservation of momentum doesn't apply because you want to eliminate the possibility of rational analysis in this case, aren't you? I forgot about that motive.

Lord Edam wrote:It would be as good as whatever was acting as the brace when Wesley was flying chairs around with the exact same device as later became a repulsor in a doorway.

I think it's important to note that Wesley's device is undoubtedly obeying conservation of momentum by bracing against something, since he uses the exact same principle to save the ship when he modifies the ship's tractor beam to push away from the Tsiolkovsky.

The first theory seems most plausible. It is highly unlikely that personal shields wont stop a bullet. The forcefield generated by the tiny mobile emitter used in the voyger EMH was strong enough to take revolver rounds in "future's end". There was some recoil when the bullets struck but the forcefield was not compromised.

However it is likely that larger caliber rounds will overwhelm any personal shields the federation may construct. Kinetic energy from a bullet will eventualy be transmitted to the shield generator itself. Any personal shield generator must be physicaly worn by the user which means due to the law of conservation of momentum anyone wearing a personal shield will feel the same amount of pain someone wearing a bulletproof vest does when they are shot. Given a powerful enough firearm such as a heavy machinegun the brute force trauma can be fatal.

Lord Edam wrote:It would be as good as whatever was acting as the brace when Wesley was flying chairs around with the exact same device as later became a repulsor in a doorway.

How do we know that the device didn't cancel the weight of the object? Also, you know as well as I do that the "repulsor" in engineering wasn't simply Wesley's "unbraced" device. He plugged it into the ships' systems to make that forcefield.

I don't know if this was covered or not... Anyway, when Wesley has the tractor beam on the Enterprise reconfigured, he uses it to push the ship away. The Oberth was pushed one direction while the Enterprise was pushed another. Momentum. Hence whatever Wesley was doing with the handheld model had the thing anchored to something. That doesn't change the fact that it makes for a rather interesting device. Able to partialy negate gravity and redistribute counter effects into something else. If this could be turned into a portable shield I could see it being fairly useful. Any infantry near a receptor would be able to utilize said shields to be protected against projectile weaponry. Such a system does not break laws of physics as we know it, it just kinda sidesteps the issue.

Alyeska wrote:I don't know if this was covered or not... Anyway, when Wesley has the tractor beam on the Enterprise reconfigured, he uses it to push the ship away. The Oberth was pushed one direction while the Enterprise was pushed another. Momentum. Hence whatever Wesley was doing with the handheld model had the thing anchored to something. That doesn't change the fact that it makes for a rather interesting device. Able to partialy negate gravity and redistribute counter effects into something else. If this could be turned into a portable shield I could see it being fairly useful. Any infantry near a receptor would be able to utilize said shields to be protected against projectile weaponry. Such a system does not break laws of physics as we know it, it just kinda sidesteps the issue.

Except that if it's carried on the man, it will be anchored to him, so he will catch the reaction forces on his body. If he plants it on the ground to anchor it there (a la Geordi's flame shields in TNG), then it would be more resistant to physical impactors unless they're simply too big or fast, but the tactical flexibility would be poor.

AdmiralKanos wrote:

Alyeska wrote:I don't know if this was covered or not... Anyway, when Wesley has the tractor beam on the Enterprise reconfigured, he uses it to push the ship away. The Oberth was pushed one direction while the Enterprise was pushed another. Momentum. Hence whatever Wesley was doing with the handheld model had the thing anchored to something. That doesn't change the fact that it makes for a rather interesting device. Able to partialy negate gravity and redistribute counter effects into something else. If this could be turned into a portable shield I could see it being fairly useful. Any infantry near a receptor would be able to utilize said shields to be protected against projectile weaponry. Such a system does not break laws of physics as we know it, it just kinda sidesteps the issue.

Except that if it's carried on the man, it will be anchored to him, so he will catch the reaction forces on his body. If he plants it on the ground to anchor it there (a la Geordi's flame shields in TNG), then it would be more resistant to physical impactors unless they're simply too big or fast, but the tactical flexibility would be poor.

Then how did Wesley pick up the chair while holding the projector in his hands?

Alyeska wrote:Then how did Wesley pick up the chair while holding the projector in his hands?

What makes you think this chair was too heavy for Wesley to lift? There's no reason he shouldn't be able to bear that weight.

Ted C wrote:

Alyeska wrote:Then how did Wesley pick up the chair while holding the projector in his hands?

What makes you think this chair was too heavy for Wesley to lift? There's no reason he shouldn't be able to bear that weight.

Look at Wesley's arms and how he is positioning to pick up the chair. If he was directly picking up the weight then he is a freaking weightlifter.

Alyeska wrote:Then how did Wesley pick up the chair while holding the projector in his hands?

I don't remember that part, but I'll take your word for it.

If we assume the chair is fairly heavy, we may be forced to rationalize it as a device which can levitate things by putting an antigrav "cushion" underneath them, in effect pushing against the floor rather than the device itself (analogous to putting an air balloon under an object and inflating it from a pump which you're holding in your hand). Either that, or it simply cancels the effect of the ship's artificial-grav field in its locality. The preferred Edam solution (decide that Conservation of Momentum is ignored) is just silly; by that token, ships should not even shake when objects hit their shields, and we know for a fact that this is not the case.