Category Archives: Physics

The Magnus Effect and its Broad Applications: From Sports to Ballistics to Dam Busting in WW II

The Magnus effect occurs when a moving spherical or cylindrical body has a spin. The observed effect is that the moving, spinning body moves away from the intended direction of travel. The spin alters the airflow around the moving body and, by conservation of momentum, generates the Magnus force. In the case of a flying (thrown) backspinnning round body shown below, the Magnus force is a lift.

Sketch_of_Magnus_effectSource: Wikipedia

The Magnus force is named for German physicist Heinrich Gustav Magnus, who described the effect in 1852. Other scientists had described the effect long before Magnus, notably Isaac Newton (in 1672) and British mathematician and ballistic researcher Benjamin Robins (in 1742), but it was Magnus who got the honor.

We can see the Magnus effect at work in sports and in other applications discussed below.


The pitcher can impart a spin in a selected direction to throw a curveball, slider or other pitch. Major League Baseball (MLB) uses a system called PITCHf/x, which is installed in every MLB stadium, to track the speed and trajectory of pitched baseballs. The system calculates two values, BRK and PFX, related to the Magnus effect:

  • BRK is a measure of the amount of bend in the trajectory at its greatest distance from a straight line
  • PFX is a measure of the deflection of the baseball due to the spin and drag forces from the path it would have taken under the influence of gravity alone

You can find more information of PITCHf/x at the following links:



A backspin on a golf ball creates a lift, as shown in the diagram above, helping to extend the range of the shot. A topspin has the opposite effect, shortening the ball’s trajectory. A spin about a vertical or diagonal axis results in a slice or hook to the right or left, invariably putting the ball into deep grass or some other course hazard. I have trouble visualizing how a golfer imparts a spin about the ball’s vertical or diagonal axis, but apparently it is a lot easier that you might think.

Extreme basketball

Thanks to Dave Groce, who forwarded the following link to a video that demonstrates how the Magnus effect helped a group in Tasmania sink a basketball from the top of a dam.  I have a feeling that there were a lot more basketballs at the bottom of the dam than are shown in the video.


A spinning bullet will encounter a Magnus force if it yaws slightly in flight (i.e., direction of the central axis of the bullet is slightly different than its direction of flight, or velocity vector) or is shot into a crosswind. The direction of the Magnus force will depend on the direction of yaw or crosswind. A sniper shooting at long range needs to consider the Magnus effect.

WW II Dambusters

As reported on the Bomber Command website (

 “The Dams Raid was conceived in the brilliant mind of Barnes Wallis, an experienced aircraft designer. Wallis had designed the very successful Wellington bomber that had been operational since the beginning of the war and, in his spare time, he searched for weaknesses in the enemy’s industrial infrastructure. The hydroelectric dams of the highly Ruhr Valley became his focus.

He devised a cylindrical, 9,500 pound weapon that could be dropped at low level while rotating backwards at 500 rpm. Released from a height of 60 feet, about 450 yards from the dam, and at a speed of 230 miles per hour, the weapon would then skip along the water (and over any torpedo nets) until it struck the dam wall, the spinning maintaining the weapon’s stability and slowing it down.

The backward rotation would then cause the cylinder to roll down the dam wall where it would explode at a predetermined depth. The wall would be weakened and the great weight of water would cause the dam to collapse.”

Experiments performed by Wallis demonstrated that the Magnus effect gave aerodynamic lift to the bomb and thereby increased the number of bounces before the bomb either struck the dam or stopped bouncing and sank.

p_damsraid1bSource: Bomber Command Museum

There is much more information on Sir Barnes Wallis and the Dams Raid on the Bomber Command website.

For more information, I also recommend the book, “Dam Busters.” By James Holland, published in 2012 by Grove Press, New York.



Kurzgesagt Explains the Fermi Paradox: Where are all the aliens?

Kurzgesagt (German for “in a nutshell“) is a Munich-based design studio with a distinctive perspective on design and animation in the fields of education, science and commerce. For more background information on Kurzgesagt, visit their website at:

Then, select “Projects” or “YouTube” on the menu on the left side of the screen to access their library of animated video briefings. The icons for some of your choices in the “Projects” menu are shown below. All project videos also are available on YouTube. I hope you enjoy these briefings.

Kurzgesagt1  The Fermi Paradox

Kurzgesagt2 Who Invented the Internet?

Kurzgesagt3  Time Explained

Kurzgesagt4 Is Nuclear Energy Good or Bad?

LightSail to Demonstrate the Feasibility of Solar Sail Technology for Future Spacecraft Propulsion

Light exerts a measurable pressure on solid objects. This was demonstrated in 1899 in an experiment conducted by Russian scientist Pyotr Nikolayevich Lebedev. This experiment also demonstrated that the pressure of light is twice as great on a reflective surface than on an absorbent surface. This is the basis for the solar sail concept for spacecraft propulsion.

Solar sailing  Source:  Planetary Society

The Japanese IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) spacecraft launched on 20 May 2010 is the world’s first spacecraft to use solar sailing as its main propulsion. The square solar sail measured 14.14 meters (46.4 feet) along its edge, with a total area of 200 square meters (2,153 square feet). Thin-film solar cells in the sail provide electric power for spacecraft systems. IKAROS was launched as a secondary payload in conjunction with the Japanese Venus Climate Orbiter. The Japanese Aerospace Exploration Agency (JAXA) claims that acceleration and attitude control of IKAROS were demonstrated during the spacecraft’s flight toward Venus. The total velocity effect over the six-month flight to Venus was reported to be 100 m/s. IKAROS continued into solar orbit while its companion spacecraft entered orbit around Venus.

The Planetary Society conceived and is executing a crowd-funded project called LightSail to continue demonstrating the feasibility of solar sail technology. You can read more at their website:

Packaged into a compact 3-unit “CubeSat” (about the size of a loaf of bread) for launch, the Planetary Society’s first LightSail spacecraft, LightSail A, hitched a ride into orbit on an Air Force Atlas V booster on 20 May 2015. The primary purpose of this first mission is to demonstrate that LightSail can deploy its 32 square meter (344 square foot) reflective Mylar solar sail properly in low Earth orbit.  Following launch and orbital checkout, the sail is expected to be deployed 28 days after launch. Thereafter, atmospheric drag will cause the orbit to decay.

LightSail A spacecraft Source: Planetary Society

You can read more about the first mission at the following link:

In a second mission planned for 2016, LightSail B will be deployed into a higher orbit with the primary purpose of demonstrating propulsion and maneuverability. LightSail B will be similar to LightSail A, with the addition of a reaction wheel that will be used to control the orientation of the spacecraft relative to the Sun. This feature should allow the spacecraft to tack obliquely relative to the photon stream from the Sun, enabling orbital altitude and/or inclination to be changed.

You can find more information on solar sail physics and use of this technology at the following link:

 29 May 2015, Update 1:

After launch, the LightSail A spacecraft’s computer was disabled by a software problem and the spacecraft lost communications with Earth.  Reset commands have failed to reboot the computer.  The computer and communications problems occurred before the solar sail was scheduled to be deployed.

31 May 2015, Update 2:

The LightSail A computer successfully rebooted and communications between the spacecraft and the ground station have been restored.  The plan is for ground controllers to install a software fix, and then continue the mission.

9 June 2015, Update 3:

The Planetary Society announced that the LightSail A spacecraft successfully completed its primary objective of deploying a solar sail in low-Earth orbit.

20150609_ls-a-sails-out_f840  Source: Planetary Society

Read their detailed announcement at the following link:

CERN Announces Large Hadron Collider (LHC) Return to Operation

After a two-year shutdown for modifications that are expected to nearly double the maximum energy of LHC to 13 TeV, CERN has completed a long re-test process and restored LHC to operation. You can read about the restart process at the following link:

image   Source: CERN

Re-start was delayed by an intermittent short circuit that had to be resolved after the superconducting machine had already been cooled down. Maintenance and repair is time-consuming when a superconducting component or system is involved, since the equipment must be warmed up before it can be serviced, and then cooled down again to 1.9 degrees Celsius before LHC operation can resume.

With the LHC back in operation, the search for more Higgs Bosons and signs of supersymmetry continues. Read more about LHC operations at the following link:

You also might want to review Maria Spiropulo’s 27 August 2014 Lyncean presentation: “The Future of the Higgs Boson.” You can find this presentation in the Past Meetings section of this Lyncean website.


History of the DOE National Laboratories

Many at SAIC worked at or for one or more DOE national laboratories at some point in their careers.   The following link to the DOE Office of Scientific & Technical Information (OSTI) web site provides links to other web sites with historical information on the various national labs.

For example, on this OSTI web page, you can select the Idaho National Laboratory link, and a pop-up menu will display the available documents.  If you select, “Proving the Principle: A History of the Idaho Engineering and Environmental Laboratory, 1949 – 1999,” this will take you to an INL web site that includes a 25 chapter history + a 2000 – 2010 addendum, all organized for chapter-by-chapter web access.

I hope you find some something of interest via the OSTI website.

Scientists Will Soon Use Natural Cosmic Radiation to Peer Inside Fukushima’s Mangled Reactor

Using a technique called muon tomography, 21-foot by 21-foot muon detectors will be used to collect data over periods of months to develop high-resolution images of the damaged Fukushima reactors.
Fukushima muon tomography setup Source: LANL
Read a brief article on this subject at the following link:
More details are in Los Alamos report LA-UR-12-20494, “Our Next Two Steps for Fukushima Daiichi Muon Tomography”, which is the source of the above diagram.  You can view or download this LANL report for free at the following link:

Quantum Radar Explained

It’s also called “quantum illumination” using “entangled quantum particles”.  I think I missed that class, so I found this relatively simple explanation to be helpful.

Quantum radarImage source: S. Barzanjeh et al., Phys. Rev. Lett.

Check out the article at the following link:

GPS and Two Alternatives You May Not Have Heard About: GLONASS and Galileo

U.S. Global Positioning System (GPS)

The U.S. military-operated Global Positioning System (GPS) achieved full operational capability in 1995 and was declared a “dual-use” (military and civilian) system in 1996.  Today, GPS functionality is embedded in many of the electronic products and vehicles we use on a daily basis.  You’ll find plenty of information on GPS at the following link:

Russian GLONASS:

Globalnaya Navigatsionnaya Sputnikovaya Sistema (Global Navigation Satellite System), GLONASS is a Russian military-operated satellite-based navigation system.   The intent for GLONASS to be a dual-use system was declared in 2007 and full global coverage was achieved in 2011.  By the end of 2011, GLONASS claims it met a goal of matching GPS accuracy and reliability, and GLONASS may be more accurate than GPS at high latitudes because of the higher inclination of GLONASS satellite orbits.  iPhones and several types of Android phones have both GLONASS and GPS chips and may use both satellite signals to improve navigation results.  Check out the story at the following link:

European Galileo:

While European independence from GPS & GLONASS was a key goal behind the creation of the new system, Galileo is intended to be 100% interoperable with GPS and GLONASS.  The first two operational Galileo satellites were launched in October 2011, with two more following in October 2012.  These four Galileo satellites represent the operational nucleus of the future 30-satellite constellation.  The 5th & 6th Galileo satellites were launched in August 2014 into incorrect orbits and are not operational.

You can get more information on Galileo at the following European Space Agency web site:

Relativistic corrections needed for satellite navigation system accuracy:

These three satellite navigation systems depend on relativistic corrections to ensure that accurate data are delivered to the end users.  You can find a short article entitled, “Real-World Relativity: The GPS Navigation System,”  at the following link: