SNL gel/liquid sketch update

With the renewed attention on airport security, someone was bound to find the SNL sketch referenced here. (Thanks to The Daily Dish By Andrew Sullivan for the link.)

A few words from the TSA

I wrote TSA through their web site, asking if they used a particular definition of gel in their rules for carry-on luggage. {I identified myself as a science blogger.} The TSA Contact Center responded by saying

"Regardless of whether an item is on the prohibited or permitted items list, the Transportation Security Officers (TSO's) have discretion to prohibit an individual from carrying an item through the screening checkpoint or onboard an aircraft if the item poses a security threat. Therefore, TSA security screening personnel make the final decision on whether to permit items like certain gels into the sterile area of the airport."

I infer from this that TSA's definition of a gel is somewhat arbitrary. The security officers have jurisdiction over all fluid and semi-fluid materials.

Liquids versus Gels

The standard thermodynamic definition of a liquid is a material that takes the shape but not the volume of its container. A gel is a material that exhibits no flow when in steady-state. Gelatin is a common gel.

"Is a turkey sandwich a gel or liquid?"

Three years ago, Saturday Night Live broadcast a sketch on Transportation Security Administration screener training. In the sketch, the aspiring scanners discuss liquids, gels, and the differences between them. Here’s some of the dialogue…
A video doesn’t appear to be available online, but here’s the script.

Chris: You want to name some liquids, and/or some gels!
Dane: Liquids and gels.
[ no response from the stone-faced recruits ]
Dane: Anything you've got!
Kenan: Water.
Dane: [ pleased ] Water! That is a liquid! Good!
Maya: Toothpaste!!
Chris: Bingo!! That is a gel!!
Amy: Shampoo!!
Dane: [ smiling ] Wow! you guys are doing great!

UPDATE (9/2010): A link to a video of the sketch is here.

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