Laser Rooms and Password Screens

I’m a big fan of lasers. They look cool, they do cool stuff, and the word even sounds cool. (Did you know it’s an acronym?) Maybe that’s why it kind of bugs me when they are misused in supposedly-realistic fiction. Like in movies and TV shows, where there’s a room full of lasers protecting a room or a vault or something. Here are my complaints about that:

1. Lasers are light beams, so you can’t see them unless they hit something. If you could, you’d see sunlight coming out of the air, and you couldn’t see anything at all because of the glare. So unless there’s dust in the room, if you can see the lasers in one of those laser rooms, you already know that the movie or TV show has screwed up. (And if you can see dust without the intruders putting it there, that’s fake too – why would you want the lasers to be visible if you’re the one they’re protecting?)
2. There’s always a path through them, for someone athletic enough. Why? Given the number of lasers in these rooms, you could easily just make a dense grid, instead of spreading them out across a wide area, creating person-sized gaps.
3. When they move, that looks like added security, but it’s also totally fake. Laser sensors work because a sensor in the wall is continuously picking up the laser light. When you step in the way, the signal stops, and the alarm goes off. If the laser is moving around the room, you’d have to have the sensor moving around the room too, which you couldn’t do (and which is clearly not happening in shows that do this).
4. When the lasers cut stuff, that also feels a little off. Of course lasers can cut things, but it would take a lot of power to have them on, and of course the “sensor” on the other end would have to be absorbing the laser energy somehow. It would be a lot more efficient to have the lasers just be sensors, and then have guns mounted in the wall that fire when the sensor goes off.
5. In movies and TV, these elaborate security devices never, ever work. Have you ever seen a laser room in a show that the person trying to break in didn’t get past? I didn’t think so.

Speaking of things that never work, I just remembered something else that always happens in fiction that bugs me so much that I added it to the title: People logging on to other people’s computers. I’m not talking about someone’s house, where there’s no password at all. I’m talking about folks guessing a one-word password, or just glancing over at the screen of some employee who has been lured away from his or her desk. No self-respecting corporation lets its employees leave computers unlocked or pick passwords that are a single word from a dictionary. Sure, you could probably crack most people’s passwords with brute force software (that is, guessing thousands of times in quick succession). But a human guessing words? Not a chance. But it happens all the time in even the most “serious” tech-fiction.

There. I’ve said it. I feel better now.