Greg H.

You don't need a 3d printer to make a gun. People have been making improvised weapons out of spare parts since at least WWII - some of them surprisingly accurate. http://en.wikipedia.org/wiki/Improvised_firearm As to your question - gun control isn't the problem. Rabid over-zealous gun control, on the other hand is. Reasonable (yes, I know, that's a subjective term) gun control coupled with responsible gun ownership is what is needed.

Quantum mechanics teaches us that there is always a chance, however infinitesimal it might be.

What you've got here is a false dichotomy because you haven't shown why the third option - that both exist - is untenable. "Tradition says so" isn't much of a reason. Tradition also said the earth was flat and we see how well that worked out.

Cheers Cap'n. So, that's how much it would accelerate the helmet. How much it accelerated the actual skull would depend on the padding and the web suspension. But no, that's definitely not going to be nice to your brain.

Yeah, no clue, but that's going to ring his bell, that's for sure. It might be enough to daze him, depending on how much the helmet can absorb. Edit: And that's assuming the helmet he was using was designed to small "point" intrusions like a bullet, rather than wide area crushing (such as a motorcycle or sports helmet). Assuming he's using a bog-standard military Kevlar helmet, they're rated up to 1600 ft/sec (according to http://www.compassar...ion-helmets.htm), but that doesn't give us any information on how much of the force transfers to the skull. I'm going to dig a bit and see what I can find. Edit 2: Mooey, I did find some numbers that might require you to redo some calculations. According to http://www.operation...rg/helmets.html: So the bullet will actually travel closer to 3.8 cm before it stops - the strap suspension in the helmet keeps the dimple from smacking the skull full force. Some quick napkin math shows that reduces the force down to about 27 kN. And yet another edit According to Wikipedia, the threshold for a concussion in sports medicine is around 70-75 g's of acceleration. Can we convert the kN to g-force?

The number I found was 1220 feet/second on the high end for .45 ACP and a low end of about 900 f/s.

That depends entirely on the shooter's goal. In this case, his goal was (apparently) simply to shoot randomly into a crowd inflicting as much harm as possible. Distracting him isn't necessarily going to impact his "mission" because it's not based on any kind of precision. If his intended target gets missed, chances are high he still hits someone. The only real way to prevent him from inflicting more harm would be to put him down, at least long enough to incapacitate his ability to fire more rounds. You'd have more effect tackling him from behind, and pinning him down with sheer mass.

They can call NASA if they feel the need to lodge a complaint.

Physics works. The evidence is all around you, from the car you drive (assuming you have one) to the computer you're posting these messages from. Our knowledge of physics is certainly not complete, but that's a far cry from saying it's wrong.

While there is no "typical" police issue weapon in the US (each department buys whatever suits them), the most popular loads now seem to be 9mm, .40, and .45 ACP (source - various Wikipedia articles*). IIRC, someone earlier in this thread mentioned the attacker was suited up in a Type IIIA armor set, which is rated to protect against weapons of .357 and .44 Magnum rounds with a muzzle velocity under 1400 ft/s. (Personal Armor Performance Standards). A .45 ACP can achieve about 1220 ft/s of muzzle velocity(.45 ACP on Wiki), which means it's not going through the armor, unless you happen to get lucky and hit the guy in a weak spot. *As a sample of the articles, see the following: LAPD Service Weapons NYPD Service Weapons FBI Service Weapons Edit to add a final source

As a rule of thumb, no. In general, you'll only see the off duty cop approach when it's some kind of special event, and then only if the city/county code requires them for crowd control. The theater (in this case) has to pay for them after all, and that cuts into their profits for the event.

We (speaking generally here) refer to our internalized standard of right and wrong - these are standards that we learn as we grow and are taught to us by our parents, our peers, and our communities. If this was not the case - if morality and ethics were really provided to us by an outside force or entity, why do children seem to have absolutely no concept of right and wrong? If morality is truly universal, why can't the various societies on our planet (and the various communities within those societies) reach a simple agreement on what is right and what is wrong? If we are supposed to have this innate ability to discern right from wrong, why did God feel the need to spell it out to us in 10 simple rules? He certainly didn't seem to think we were in possession of some innate moral compass.

While I agree with you, security guards at many American corporate facilities tend to be laughable to the point of "Why bother?" The security guard at my office is probably 97 years old (ok, that's an exaggeration, but not much of one - he's got to be at least 70) and he only sits at one entrance. The other one they simply rely on the RFID badge device to make sure no one who isn't supposed to be there gets inside. Penetrating this office for someone intent on doing harm is so easy it's laughable. Public venues such as malls, shopping centers, and theaters (movie and otherwise) are even worse. You might have eight or ten on duty guards to cover a mall of a couple hundred thousand square feet. Even if they do see something on the cameras, by the time they get to that location, the guy is already inside buried in a crowd of thousands. At a small facility, such as the theater standing on it's own, you'd be lucky if there is a single security guard, and if there is, he's out front, not in the back, so getting inside is just a matter of waiting until someone comes out one of the exit doors and using it to get inside. Once again I have to agree with Mooey that stopping the attack before it starts is always the best answer. But that required a diligence in observation that comes with a price tag. The over-arching issue is that people in America feel relatively safe, and security costs money. We'll pay more attention for a few months (maybe longer in the area the event actually happened in) but after a while, we get lulled back into complacency. Until the next time.

I have to agree with mooey here. Dressed like he was, with the equipment that he had, you would have needed someone with an anti-material style rifle to punch through that armor and be sure of a kill. Not the sort of thing one normally takes the movies, and probably next to useless is those kinds of close quarters anyway. In a situation like this, the best thing for everyone to do is get the hell out of the way.

The principle of least action does not say that nature will never do work. It says that nature will never do more work than is necessary, which is a minor, but fundamental, difference. (At least from my understanding of it - admittedly, it could be flawed).

DH, Thanks for this - I admit, it was a bit of a simplistic case, and I see the issues with it now that you've pointed them out. Your answer makes sense, and I appreciate the clarification. Cheers!

I recommend stronger Jello. Or less bugs. One or the other. Your gun rack has a gun rack.

You say that like it's a bad thing.

For profit privatized health insurance is a conflict of interest is ever I saw one. Their goal is not to make you healthy, it's to make a profit for their shareholders.

Cool. And I guess if you get bored you can take shots at bland food with it too.

Our understanding of morality comes from our society. The need for it to come from God is pure bilge because that automatically precludes the idea that non-believers can be good people.

Of course. Were you planning on supplying any, or were you going to continue ambling down nonsense lane?

So if I toss salt on a person is that now assault with intent to kill? On a serious note, how does table salt work exactly? Does it dehydrate them by clinging to their exoskeletons?

Ok, I give up. This makes zero sense to me. It's like the OP is rehearsing playing a crazy person in an Internet chat room.