Friday, January 13, 2017

Reaction Time Measurement Application

For my next book, I need to take a lot of data on the reaction times of humans. In order to make this investigation easier, I wrote a little program in processing to measure reaction times using three tests:
  • Simple reaction time - This is a measure of how quickly you can respond to a stimulus. The goal is to click the mouse as soon as possible after an image of a light bulb turns green.
  • Choice reaction time - This is a measure of how quickly you can respond to a stimulus where a simple decision needs to be made. In this case, if the light bulb turns yellow, left click your mouse, and if the bulb turns blue, right click your mouse.
  • Aim test - This is a measure of how well you can quickly click on a small, randomly located target. As simple as it sounds, this is difficult to do quickly.
The fun part comes when we start making comparisons. We might compare martial artists to other athletes or avid gamers. We might also compare baseline data to "impaired" data (taken after a few cups of coffee or after a few beers).

If you'd like to help me gather reaction time data for my upcoming book, here are some quick instructions:
  1. Download the program and unzip it. Open the folder and run "reaction_time.exe" (you will need Java 8.0 installed on your machine).
  2. Fill out your information and use the tabs at the top to take all three tests. If you want to take it several times, if you want to take it while impaired, or if you want your friends to take it too, just remember to change the info on the first tab.
  3. Send the data back to me. It will save your data in a csv file called "REACTION_TIME_DATA_LOG.csv" in the same folder as the program. Email it to me at Let me know in your email if you are a martial artist, or a gamer, or if there is anything else you think might make set your reaction times apart from other people.
If you want to compile it yourself, peek under the hood, or re-purpose it for your own project, you can also download the original processing scripts.

Thanks for your help!

Wednesday, September 9, 2015

The Book Arrives

Fight Like a Physicist is finally here! It's been a very long road to get to this point, and it's amazing to have a tangible representation of that work in my hands.

This first copy belongs to Jen Hahn for supporting my work and tolerating my long hours, so I'll have to borrow hers until I get one of my own in the mail.

Looking at the book again with fresh eyes, I can imagine it's going to piss a lot of people off, and that's fine. You can't advance human knowledge without annoying the people who were happy with the the state of the world before you came along. All I can really hope for is that for every person who gets pissed off as a result of this book, two people start to ask tough questions about how they train or what it really means to be safe. If enough of us start asking tough questions, maybe one day, when someone asks a simple question, such as "Why do boxers wear gloves?" or "Why do football players wear helmets?" the answer will be a resounding "I don't know. It's pretty dumb, huh?"

Monday, August 17, 2015

A Dichotomy of Human Punches

The science for this one is not too tough, but it does seem to catch a lot of people off guard, so I figured I would turn it into a short video:

It turns out that punches are not like projectiles. Your muscles make a trade-off between adding to the velocity of a strike or adding to the effective mass, and this trade-off gives us a dichotomy based on quantities that we usually think of as changing together in simple classical mechanics scenarios.

If you want to get into the details, it is an incredibly interesting and rich topic with a lot of unanswered questions.

Tuesday, May 5, 2015

Is pi really universal?

Full disclosure: I have the first 51 digits of pi tattooed on my left calf and foot, so I am personally and permanently attached to the traditional definition of pi.
My left leg
Pi is a fundamental constant of the universe, and it is defined to be a circle's circumference divided by its diameter, or the distance around a circle divided by the distance across it. The number pi shows up in math and physics on a regular basis, even when we are not talking about circles, and it is safe to say that without an understanding of pi, we would not be as technically advanced as we are as a species today.

But if NASA is right, we will discover alien life in the next 20 years, and while that life will probably just be microbial, as a species, we should start thinking about how we would communicate with intelligent life, should we ever find it. Math is a universal language, so it is only a matter of time before humans try to show off our intelligence by demonstrating our knowledge of pi, but... what if we are wrong?

Wednesday, February 11, 2015

Science Study Break: Physics of Martial arts in the Movies

Here is a fun article covering a talk I gave yesterday at the University of Texas as a part of their Science Study Break program:

UT graduate discusses between physics and martial arts - The Daily Texan

The format of the program is pretty simple; they show a bunch of movie clips, and then discuss them with the audience, with a science-y twist of course.  The whole science study break series is pretty fun, and I highly recommend attending an event for anyone in the Austin area.

This was my first event promoting Fight Like a Physicist, and I still have a long way to go before it comes out this September.  Admittedly, some of the material is not easy to boil down to 30 second explanations without much context, so I should start figuring out which questions I can tackle easily in talks/interviews, and which ones I should just answer with "read the book!"

There was at least one special guest in attendance, too.  A former professor of mine back when I was an undergrad at UT showed up, and he was a member of the UT Judo team with me as well (1998 Texas State champs!).  He was the guy who first taught me a rear naked choke, so it was nice to see him there.

Tuesday, December 30, 2014

How to Fight a Robot: What have you gotten yourself into?

Earlier this year, I began building a full-sized humanoid robot, following the InMoov design, because I wanted to build a robotic sparring partner.  I wanted him to swing an eskrima stick at me, throw a punch at me, and even do some blocking drills.  I wanted to fight a robot.

Unfortunately, he sucks at fighting.  There is a very long list of necessary modifications before he could even throw a single punch that lands with impact, and not fall apart immediately.  Changing this robot is just not worth the effort at this point.  Instead, I have begun designing my own fighting robot from scratch.

The point is, robots are not very good at fighting in general.  With the help of a few key insights, a human could easily dominate a robot opponent in a fight.  You will probably never find yourself in a situation where you need to defend yourself against a robot in hand-to-hand combat, but just for fun, I will walk you (a human) through what it takes to fight a robot and win.

Monday, November 24, 2014

Build Project: Headlight for a Tricycle

Headlight for a Tricycle

This is a headlight I built for my son's tricycle.  It is designed to fit a fisher-price plastic tricycle, but you can tweak the designs (in openSCAD) to mount it on any kind of tricycle you like.  It is perfect for riding in the dark, and my son absolutely loves it.

If you want a cost-effective way to put a light on your own kid's tricycle, you should probably just duct tape a flashlight to the steering wheel and be done with it.  On the other hand, if you are looking for an over-the-top solution that lights up a whole damn room, costs you more than thirty bucks in parts, and is incredibly difficult to assemble, please keep reading.