Miscellaneous Physics of Baseball Links

This page contains links to articles that I have yet classified into other categories.

The Intrinsic Value of a Batted Ball by Glenn Healey and published at The Hardball Times, March 17, 2016.

Heat map showing weighted on-base average (wOBA) as a function of vertical and horizontal launch angles, for exit speed equal 93 mph.

This article is the best attempt yet to develop ''outcome-independent batting metrics", based on the characterics of the batted ball. Professor Healey applies a Kernel Density Estimation technique to HITf/x batted ball data from the MLB 2014 season to construct a continuous probability distribution of outcome probabilities as a function of the three batted ball variables: exit speed and vertical and horizontal launch angles. He uses these distributions to construct wOBA as a function of these variables, an example of which is shown in the above image. There is a wealth of information contained in images such as these and you need to read the article to learn about some of the interesting insights that result. Technical details of the mathematical approach can be found in a companion article.

How Do Hitters Perform With Their Eyes Wide Shut? by Michael Richmond, physics professor at Rochester Institute of Technology, published at Sons of Sam Horn, February 24, 2016. This excellent article is a popular summary of the experiment reported in the peer-reviewed article Contribution of Visual Information about Ball Trajectory to Baseball Hitting Accuracy, by Takatoshi Higuchi, et al. The essential experimental result is that occluding the batter's view during the final 150 ms of the pitch flight time had essentially no effect on the batter's ability to square up and hit the ball on the sweet spot. In effect, the batter could shut his eyes during that last 150 ms without adversely affecting his ability to hit the ball. This result was long suspected; now for the first time we have actual experimental evidence. You can read all about the experiment and the implications either from the original article (which is a bit technical) or from Michael's excellent summary.

Robert Adair talked this subject in his presentation Batting and Thinking [audio file] at the Science of Baseball Symposium, part of the AAAS annual meeting in February 2000. He discusses the process whereby a batter observes, processes, decides, and swings the bat. As you listen, you should also look at this excellent graphic , courtesy of the NY Times. Adair goes into much detail about this topic in his famous book, The Physics of Baseball. See also this short video clip Hitting a Major League fastball should be physically impossible

The Physics of Baseball, 1920's style

My analysis of an article from 1920 about the physics of a Babe Ruth home run, appearing in the middle of the season when Ruth hit 54 home runs, nearly doubling his own single-season record of 29 from the previous year. We know a lot more about the physics of baseball now than we did nearly 100 years ago. As a result, there is some wrong physics in the article. I discuss all of that in my analysis. My thanks to Greg Rybarczyk (@hittracker) for calling this article to my attention.

Physics of Baseball and Softball by Rod Cross This book, published in March 2011, describes the physics of baseball and softball, assuming that the reader has a basic background in both physics and mathematics. The physics is explained in a conversational style, with words and illustrations, so that the explanations make sense. The book provides an excellent opportunity to explain physics at a relatively simple level, even though the primary objective is to explain the many subtle features concerning the physics of baseball. For those readers who already know quite a bit of physics and who will be comfortable with mathematical equations, additional material of this nature will be provided in appendices. The latest research findings and statistical data have been incorporated by Cross. The book also contains many simple experiments that the reader can perform to convince themselves that the effects described do indeed exist. Cross has written the definitive treatise on the subject and I highly recommend it to all those with an interest in the science of the game.

The Acoustics of Baseball An excellent and very readable report by Professor Bob Adair, based on a talk he gave in June 2001 before the Acoustical Society of America. Another account of this is in the excellent New York Times article by Jim Glanz. Click here for a nifty graphic based on this article. Professor Adair wrote the book entitled The Physics of Baseball, 3rd Edition, which every person serious about the science of the game should read. And speaking about books, you should also check out the book by Watts and Bahill entitled Keep Your Eye on the Ball. Although not as comprehensive as Adair's, it addresses some very interesting issues and give some good explanations based on simple physics principles.

Aerodynamics of the Baseball. These are a series of web sites with information about the flight of a hit or pitched baseball through the air. An excellent site is the NASA-sponsored site Aerodynamics of Baseball, maintained by Tom Benson. Other excellent sites are The K-8 Aerodynamics Textbook and the Baseball Flight Simulator to simulate the flight of a baseball. Check our Brian Raue's site for a study he did of home run distances at Pro Player Stadium. A excellent article, The Mechanics of a Breaking Pitch appeared in the April 1997 issue of Popular Mechanics. Take particular note of the 4th page, which has a very nice description of the physics of a curveball by physicist Peter Brancazio. Finally, check out a nice description of a knuckleball, then watch a short video of Tim Wakefield in action.

The Juiced Baseball Issue. Is the baseball is "juiced." That is, is it more lively today than yesteryear? Read the account by Rawlings on their manufacturing procedures by clicking here . In 2000 MLB conducted a series of tests on baseballs. Click here to download the official report issued by Prof. Jim Sherwood of the Baseball Research Center at the University of Massachusetts/Lowell, who performed the tests. For a somewhat different take on this issue, see the nice article written by Bill Sloat in the Cleveland Plain Dealer.

Hitting and Pitching Mechanics. Three sites devoted to the mechanics of swinging a bat: Batspeed.com , Coach Preston Peavy's VSI Baseball, and Mike Epstein Hitting. Three sites devoted to the mechanics of pitching a baseball: Tom House, Dr. Mike Marshall, and American Sports Medicine Institute. Both House and Marshall are former MLB pitchers. The ASMI is run by Dr. James Andrews, the surgeon who performs most of the shoulder operations on MLB pitchers.

Maple vs. Ash: Listen to a podcast of a July 4, 2008 broadcast of NPR Science Friday, hosted by Ira Flatow. Professor Lloyd Smith gives an excellent discussion of the differences between maple and ash bats. See also woodbat.org, a site put together by Roland Hernandez. He gives detailed explanations about wood bats, "slope of grain", ring porous vs. diffuse porous woods, and different failure modes of wood bats.

Curveballs: When What You See Isn't What You Get, an NPR story from October 23, 2010, including an audio link. Be sure to scroll down to the end of the story and try out the "Curveball Illusion" cartoon. The original paper upon which this story is based may be downloaded by clicking here. The basic premise of the article is that the human visual system peceives motion differently in the central (or foveal) and perpheral parts of the eye. In particular, the peripheral vision can confuse rotational and translational motion. It is argued that this perceived distortion may contribute to a batter's perception that a breaking pitch experiences sudden changes in direction as it approaches home plate. There have been many other news stories (do a search on "curveball illusion") reporting this research. Note that some of the news stories are reporting incorrectly that the authors claim that breaking pitches do not really break. On the other hand, the connection between the illusion in the cartoon and a batter's perception has not been definitely established, nor do the authors claim that it has.

Steroids and Home Run Production. With the admission on January 11, 2010 by Mark McGuire that he used steroids, it is natural to ask what effect that might have on home run production. This question has been addressed in a paper entitled On the potential of a chemical Bonds: Possible effects of steroids on home run production in baseball written by Professor Roger Tobin (Tufts University, Department of Physics) and recently published in the American Journal of Physics. In 2009, I wrote a summary and critique of Tobin's paper that was published in SABR's Baseball Research Journal in Summer 2009. In June 2006, a story appeared online at "ESPN Page 2" by Patrick Hruby that addressed the same issue. I wrote a short set of technical notes at that time (updated Feb. 17, 2009) in an attempt to quantify the effect of increased muscle mass on bat speed.

The Gyroball What's all this gyromania about? To find out, click on the link.

Batting and Thinking. This links to an audio file of a very interesting presentation by Professor Bob Adair given at the Science of Baseball Symposium, part of the AAAS annual meeting in February 2000. He discusses the process whereby a batter observes, processes, decides, and swings the bat. As you listen, you should also look at this excellent graphic , courtesy of the NY Times.

PBS - Scientific American Frontiers. On the Ball: Baseball Tech - watch online as Alan Alda explores the science of baseball. To see the video, click here and scroll down to the Baseball Tech video.

Sites Geared Towards Younger People. The most important of these sites is Sport Science @ The Exploratorium, the superb site of The Exporatorium science museum in San Francisco.