Clarke's Third Law and Harry Potter.

[KrO2]

As I'm sure you all know, the next Harry Potter movie is coming out soon (Thursday). I'm not sure yet if I want to see it right away, but got a random idea that could be funny. We know any sufficiently advanced technology is indistinguishable from magic. So what would be some impressive-looking science trickses, given that I have until Thursday to prepare them, to pull out in front of the theater? I reread the home experiments thread, particularly the fire-related ones, and thought it might be fun to, for instance, shout "incendio" while playing with a ball of fire*, or some such trick. So, any suggestions? Bonus points for a stunt that actually has a magic spell counterpart in the HP series, but it's not too important.

*Not sure what kind of lighter fluid works for that. One of the links said naphtha or kerosene, but how about charcoal lighter fluid? All it said on the label was that it contains "petroleum distillates" and I wouldn't want to count on it having an unknown burn temperature. Wikipedia didn't say what exactly is in charcoal lighter, but it was a separate article from naphtha.
Or, can anyone suggest a good fluid to cover a hand in before lighting it? That would be even better than the fireball trick, but I don't trust most random Internet recommendations, so I'm asking here.
Is it possible to (safely) make a miniature Tesla coil with a 9V battery? Ditto the above point about the Internet.

[nehpest]

1. Build death ray.
2. Shout "avada kedavra!"
3. ???
4. PROFIT JAIL TIME

Seriously though, you might have a safer/less-jail-inducing time with, say, a "wand" that shoots a jet of water while you shout "Aguamenti." Fire makes for more impressive demonstrations sometimes, but you have to be careful about the circumstances under which you perform them.

You might also consider simulating the Patronus spell by rigging your "wand" to expel steam from dry ice.

[thoughtfully]

steam from dry ice.

Now that would be magic!

[Charlie!]

Ping pong ball held in a vertical stream of air (like from a blow-dryer) by bernoulli's principle = wingardium leviosa.

Sadly you don't have a 10T magnet so you can do it with frogs, but oh well.

Inflating a an inflatable (something) very quickly by using a gas canister that you carefully attached to it = transfiguration.

[KrO2]

Thanks for the ideas. If I do something with dry ice, what happens if I shine a laser pointer through the gas? Not that I have a laser pointer, but I can probably get one. I still haven't decided for sure on the fire-outside-a-crowded-theater ones (or, to be honest, on whether this'll happen at all) but some of these would look cool even outside of a scenario like this.

[Cynical Idealist]

If I do something with dry ice, what happens if I shine a laser pointer through the gas?

This:

[Clever-Username]

You could get some sulfer-hexafluoride and either a) make your voice awesome, or b) make stuff levitate

[iroZn]

*Not sure what kind of lighter fluid works for that. One of the links said naphtha or kerosene, but how about charcoal lighter fluid? All it said on the label was that it contains "petroleum distillates" and I wouldn't want to count on it having an unknown burn temperature. Wikipedia didn't say what exactly is in charcoal lighter, but it was a separate article from naphtha.
Or, can anyone suggest a good fluid to cover a hand in before lighting it? That would be even better than the fireball trick, but I don't trust most random Internet recommendations, so I'm asking here.

Do not do this with charcoal lighter fluid, that would be very silly and you would be spending many hours in the emergency room wishing you hadn't. Charcoal lighter fluid is meant to light charcoal which means it burns for a long time at high temperatures.

Your best bet for doing fire ball trick is to cup some naphtha/kerosene in one hand. Pass the other hand over it with a lighter (pretend you're flourishing) as the same time you pop open your hand with the fluid and you'll get a fireball, the hand with the kerosene will probably be lit for a few seconds as well but you can just close your hand and it will put it out if it starts burning.

[oxoiron]

You could get some sulfer-hexafluoride and either a) make your voice awesome, or b) make stuff levitate

Try not to suffocate when doing the 'awesome voice' thing. While it is true that nobody present would ever forget your performance, dying is hardly magical.

[Dopefish]

Try not to suffocate when doing the 'awesome voice' thing. While it is true that nobody present would ever forget your performance, dying is hardly magical.

Indeed, apparently you need to use certain breathing techniques (from what I gather, basicly breath out hard) to get it out of your lungs, since unlike helium, it's denser than air and want's to stay in there. Alternatively (or in conjunction) you can stand on your head (hang upside down) and let gravity do the work.

Still, it's something to be more careful with compared to helium (which isn't risk free, but most things aren't).

[Moose Hole]

1. Set a time bomb on the door to the theatre.
2. Shout Bombarda at the right time.
3. ... make her open the box?

[webgiant]

As I'm sure you all know, the next Harry Potter movie is coming out soon (Thursday). I'm not sure yet if I want to see it right away, but got a random idea that could be funny. We know any sufficiently advanced technology is indistinguishable from magic. So what would be some impressive-looking science trickses, given that I have until Thursday to prepare them, to pull out in front of the theater? I reread the home experiments thread, particularly the fire-related ones, and thought it might be fun to, for instance, shout "incendio" while playing with a ball of fire*, or some such trick. So, any suggestions? Bonus points for a stunt that actually has a magic spell counterpart in the HP series, but it's not too important.

*Not sure what kind of lighter fluid works for that. One of the links said naphtha or kerosene, but how about charcoal lighter fluid? All it said on the label was that it contains "petroleum distillates" and I wouldn't want to count on it having an unknown burn temperature. Wikipedia didn't say what exactly is in charcoal lighter, but it was a separate article from naphtha.
Or, can anyone suggest a good fluid to cover a hand in before lighting it? That would be even better than the fireball trick, but I don't trust most random Internet recommendations, so I'm asking here.
Is it possible to (safely) make a miniature Tesla coil with a 9V battery? Ditto the above point about the Internet.

While it might be a gray area these days to shout "fire!" in a crowded theater (most people wouldn't believe you), I'm fairly certain there is no wiggle room on the illegality of playing with fire in a crowded theater.

The only movie I have ever been to where I am the least bit interested in what people sitting around me have to say or do is "The Rocky Horror Picture Show". All other films are meant to be watched free from interference from other people at the theater.

There's a reason the scene in "Scary Movie" where "Brenda" (who has been interrupting the movie with her own nonsense) is killed by movie patrons while the killer watches in amusement is so entertaining: deep down, we all want to kill people who interrupt our movies with their own nonsense, related or unrelated.

So perform your fake spells in your living room when it comes out on DVD/Blu-Ray. Don't interrupt my (or anyone else's) effing $10 movie ticket with your cutesy BS.

Every time you interrupt a Harry Potter movie, you toss Dumbledore off the tower all over again, only now he has a kitten in one hand and a puppy in the other.

[Soralin]

Notice that he said out in front of the theater, not in it, or when the movie was playing.

[Tass]

Get some flash cotton and one of these

Then you can throw nice fireballs from an "empty" hand. I do it all the time. (Not inside the theater though)

[p1t1o]

If you burn your hand off, you will only have one person to blame.

Thats right.

The Human Torch.

What a bastard...

[webgiant]

Notice that he said out in front of the theater, not in it, or when the movie was playing.

He could delay me watching my movie while paramedics feverishly hunt around in front of the theater for his missing hand. Or arm. Or eye. Jets of blood from his stumps could make the front steps to the theater all slippery, or cause the ticket machines to malfunction. His screams could continue to interrupt the movie even after the show had started. Plus he might set me on fire with his amateurish nonsense while I wait in line for my ticket.

But yes, he did refer to doing this outside the theater. This doesn't prevent people from thinking about doing weird nonsense in the theater, so I don't feel bad about what I said.

[KrO2]

Am I still killing a puppy, a kitten, and Dumbledore if what I'm doing is "not preventing people from thinking about doing weird nonsense in the theater" instead of interrupting the movie? Also, most of your suggestions for possibilities are based on worst-case scenarios for things that weren't actually suggested by anyone.
I ended up not doing anything like these because I accidentally ended up with a ticket, and the specific place I was waiting in line was on the inside of the theater. So it's all a moot point anyway.

[konaya]

It wouldn't be that hard to make a goblet of fire, would it? All you would need is an interesting-looking cup and something with which to create blue flames (mister nozzle in the bottom, spraying isopropanol + etanol?). Then some kind of trigger to start burning something that gives a red-crimson flame (lithium, calcium, strontium; are there any liquids that will do the trick?). It would be extra awesome if you had a photo cell in there that triggered the crimson flame if you threw something in (parchment, duh).

[grythyttan]

It wouldn't be that hard to make a goblet of fire, would it? All you would need is an interesting-looking cup and something with which to create blue flames (mister nozzle in the bottom, spraying isopropanol + etanol?). Then some kind of trigger to start burning something that gives a red-crimson flame (lithium, calcium, strontium; are there any liquids that will do the trick?). It would be extra awesome if you had a photo cell in there that triggered the crimson flame if you threw something in (parchment, duh).

to make it simpler, just put the lithium, calcium or strontium on the parchment beforehand.

[konaya]

to make it simpler, just put the lithium, calcium or strontium on the parchment beforehand.

I thought of that, but it would be far cooler if you could throw parchment in and have them not being burned. Or, perhaps, just singed around the edges? And then a mechanism for throwing them out again.

[devilgoatee]

On the entire concept of the science of Harry Potter. I cant recommend enough the Methods of Rationality (http://www.fanfiction.net/s/5782108/1/Harry_Potter_and_the_Methods_of_Rationality). Harry James Potter-Evans-Verres is a rationalist to rival Feynman. The shear cleverness of investigating magic scientifically is seriously cool.

[Josephine]

I heartily agree. I was just rereading some of that now.