Episode 005 = Airplane Stacks and Backpack Hacks

2020-04-01
00:46:11

Update for problem 003-2
00:01:03–00:01:50

Manic responds "I'm amazed at how thoroughly you answered my problem. Especially with Bec going above and beyond in roping in a dentist friend."

Ding

By Manic

Problem 005-1 = What went wrong with the audio of episode 003?
00:02:39–00:13:56

Problem poser: Listeners
Problem solver: Matt

Problem statement

When episode 003 was released, a lot of listeners replied they couldn't hear Bec, or she was very quiet, or she felt very far away. Some said she was phoning in from the ISS.

Solution attempt

Producer John Harvey explains that Bec's waveform was out of phase and had to be flipped. Flipping a sound wave just inverts the wave form. Adding opposite sound waves cancels them out. This is the idea behind noise cancelling headphones, and can also be used to remove vocals from songs.

Using the phase of the audio and weird combinations of the channels, an approximation of surround sound can be encoded in stereo channels. This is called Matrix Decoding.

A link to the broken episode can be found in the show notes. Listeners are encouraged to play it on a variety of weird devices. Bec also provides a weird audio file that has caused problems with some venue audio setups.

Ding

A "ding" by John

Problem 005-2 = The best place to put a backpack on a crowded train
00:13:59–00:18:22

Problem poser: Bridget B., on Twitter
Problem solver: Bec

Problem statement

If you're on a crowded tube train with a backpack, where is the best place to put it? On the floor, people assume it's a space to stand in. In my hand, it lurches into people. How can I get in people's way the least?

Solution attempt

Bec likes big backpacks and cannot lie them on the ground in the tube.

Solution 1: There need to be dedicated backpack carriages for backpackers where half of people are really tall and the other half is short. Alternatively, put some people in upside-down like Tetris.

Solution 2: Wear the backpack on your front, put your clothes over it, and wear a "baby on board" badge. People will stay clear of your bag and you might even get a seat.

Bridget gets to decide whether this solves the problem.

Problem 005-3 = How many Boeing 737s will fit?
00:18:24–00:27:33

Problem poser: Rob, via email
Problem solver: Matt

Problem statement

As an air traffic controller, I am bound by certain restrictions for safety: 5 nautical miles laterally, and 1000 ft. Which, let's be honest, is a lot of room. Go out and run 5 miles. That's how close I'm allowed to have two aircraft at the same altitude. That's a ton of space, right? I could easily fit more in there. But then I wondered: How much more? So my question is: In a 3-dimensional space with a radius of 5 nm and 1000 ft high, just how many airplanes could I cram in there and have none of them touching? Not travelling per se, but a frozen snapshot in time, assuming each aircraft is a Boeing 737, for sake of measurement ease. Thanks!

Solution attempt

Matt commends the level of precision and detail in the question. However, Matt did not run the 5 miles. The described volume is a cylinder. While one might think the cylinder would be 2000 ft high, the question was very clear about its height.

Matt builds an aircraft cake with 24 layers and 177'987 planes per layer, for a total of just over 4.2 million planes. If you interlace the wings, you can fit approximately 6'334'728 planes instead. This is a packing problem, which are notoriously difficult. You might fit even more by computer simulation. Nowhere in the question does Rob state the aircraft needs to be intact, so you could fit even more by compressing them.

However, the aircraft has only been ordered 15'115 times, of which 10'575 have been delivered. So the actual answer is just: All of them.

Ding

A "ding" by Bec

Problem 005-4 = Making a perfect guest bedroom
00:27:36–00:38:29

Problem poser: Matt
Problem solver: Bec

Problem statement

In my house, Matt has a spare guest bedroom. What has to happen to make that the perfect guest bedroom for people who stay over? Current inventory. Bedside table with a lamp, USB power outlets built into the wall socket. And a bed.

Solution attempt

Suggestion 1: Get rid of them boxes.

Suggestion 2: If you expect people to stay for a few nights (which is not the case here), a space to hang and put clothes.

Listeners' favourite things in their bedrooms: A bed and comfortable mattress (which is already in place). A (cuddly) toy or figurine, possibly puzzles. A quilt. A partner (Lucy?). A pet (including kids; befriend/steal neighbour's cat). A Spider That Lives In The Room And Catches Flies. A Star Wars pillow case. A butt (by Picasso). A Bec shrine (or for the specific guest).

Bec provides Matt with a futuristic garden. It's a toy, but has live, so it's a pet, and it's space-related, so it's related to Matt's partner.

Ding

A "ding" by Bec

Update for problem 004-3
00:38:32–00:44:08

Matt assumed Bec lived in a 10 m by 10 m by 10 m void (1000 m³). Bec measured her flat, which is 8 m by 6 m by 2.3 m (110 m³). Matt was off by an order of magnitude, which means a factor of 10. As an example, 3 orders of magnitude is a 1000 times difference. Matt's error means Bec's house would've been full of rice two days sooner.