Monday, June 23, 2014

Spreadsheet Template for Sharing Cost Among Friends

My genius friend Daniel Martin-Alarcon (at right) built a masterpiece G-Docs spreadsheet template for splitting costs among friends and/or roommates.

This template is entirely free and editable by the public so go ahead and fill it up Internets! ... but you probably want to make a copy for serious use ...

Here is the link in full textual glory:

My roommates and I have been using this for about a year – from party supplies to toilet paper – it is ridiculously convenient.

Here is an example: I bought two things, that benefited myself (N1) and my 2 roommates (N2, N3). My "anonymous roomie" bought one thing which benefited all of us.

Here we immediately see who owes money and who is owed. (some names redacted).

If they pay you back, it is logged in the system and it all balances out. The beauty of using this (and why it works so well with long term friends and/or roommates) is that they don't have to actually pay you back directly. Instead they can pay the next electric bill or pay a mutual friend that you owe money to, things will even out (and if they don't you can add colors to highlight scumbag friends).

If you liked this doc - search up Daniel's email address here and thank him for having me post this here, in his own words:
for the greater enlightenment of humanity

Monday, June 16, 2014

Low cost Schlieren Visualization

Have you ever wanted to see air? A couple weeks ago I made an attempt using the difference between two images ... calling it a poor man's Schlieren imaging.
Last week, I managed to get a proper Schlieren imaging setup built for only $9 (not counting the cost of a DSLR camera). It worked well enough that the setup graduated to my website: DIY Schlieren Flow Visualization, and a youtube video with cool(?) music in the background.

This is a picture of the setup:

But really you should checkout the page on my website with the description here:

Thursday, June 12, 2014

Open Letter to Discovery Kids

Dear Discovery Kids / Paragon Publishing,

My son recently got this book as a gift:
It is a nice enough book, with lots of pictures, many of them nominally 3D. I guess that counts as "bringing learning to life." However, one (non-3D) picture caught my eye:
Firstly, I am please to see that Pluto is not in the picture. Nevertheless, there is something very wrong with it. Discovery Kids, I'll give you a few seconds to see if you can find it. ... ... See it yet? And no, I'm not talking about the bizarre green color of space -- maybe it's a garish false-color IR photo or something. What I concerned about is the source of the light in this picture. I was under the impression that the Sun is the primary light source in our solar system. Yet, there appears to be a far brighter light source off the the left hand side of space, since the sides of planets Saturn, Earth, Mercury and Uranus that face the Sun are all in shadow! (Yet, strangely, the Sun isn't?) This is a pretty sad mistake.

I wanted to find the source of this image. A quick look at the photo acknowledgements showed me that the way you produced this book was to simply use a ton of stock images, with a handful NASA images thrown in:
Now, granted you don't want to spend lots of money to make a cheap book, and you could have chosen even worse stock images (check out this one; it has the sun shadowed!), but if you're trying to produce educational books, at least make sure it's correct! This isn't a "subtle" mistake like the Wrong Stars In Titanic Movie debacle, this is something glaringly obvious on the main focus of a two-page spread that you should have caught! When I asked my five year old son what was wrong with the picture he figured it out, so your editorial team should definitely have caught it. I hope you do better in your other books.

Monday, June 02, 2014

Poor man Schlieren imaging

I recently learned about Schlieren imaging, got excited by this video, and thought I would try a crude version.
Details may follow eventually, but in the meantime, here are two photos of the air above a flame. (Zoom in on the lower one to see it closer).

Of course both of my brothers were already familiar with it (being a physicist and an aerospace engineer).