Category Archives: Physics

100th Anniversary of Einstein’s General Theory of Relativity and the Advent of a New Generation of Gravity Wave Detectors

Peter Lobner

One hundred years ago, Albert Einstein presented his General Theory of Relativity in November 1915, at the Prussian Academy of Science. Happy Anniversary, Dr. Einstein!

Today, general relativity is being tested with unprecedented accuracy with a new generation of gravity-wave “telescopes” in the U.S., Italy, Germany, and Japan. All are attempting to directly detect gravity waves, which are the long-predicted quakes in space-time arising from cataclysmic cosmic sources.

The status of four gravity-wave telescopes is summarized below.

USA: Laser Interferometer Gravitational-Wave Observatory (LIGO)

LIGO is a multi-kilometer-scale gravitational wave detector that uses laser interferometry to, hopefully, measure the minute ripples in space-time caused by passing gravitational waves. LIGO consists of two widely separated interferometers within the United States; one in Hanford, WA and the other in Livingston, LA. These facilities are operated in unison to detect gravitational waves. The Livingston and Hanford LIGO sites are shown in the following photos (Hanford above, Livingston below):

ligo-hanford-aerial-02Source LIGO Caltechligo-livingston-aerial-03Source: LIGO Caltech

LIGO is operated by Caltech and MIT and is supported by the National Academy of Sciences. For more information, visit the LIGO website at the following link:

Basically, LIGO is similar to the traditional interferometer used in 1887 in the famous Michelson-Morley experiment (–Morley_experiment). However, the LIGO interferometer incorporates novel features to greatly increase its sensitivity. The basic arrangement of the interferometer is shown in the following diagram.

LIGO experiment setupSource: LIGO Caltech

Each leg of the interferometer has a physical length of 4 km and is a resonant Fabry-Perot cavity that uses a complex set of mirrors to extend the effective arm length by a factor of 400 to 1,600 km.

On 18 September 2015, the first official “observing run” using LIGO’s advanced detectors began. This “observing run” is planned to last three months. LIGO’s advanced detectors are already three times more sensitive than Initial LIGO was by the end of its observational lifetime in 2007. You can read about this milestone event at the following link:

You also can find much more information on the LIGO Scientific Collaboration (LSC) at the following link:

Italy: VIRGO

VIRGO is installed near Pisa, Italy, at the site of the European Gravitational Observatory ( VIRGO is intended to directly observe gravitational waves using a Michelson interferometer with arms that are 3 km long, with resonant Fabry-Perot cavities that increase the effective arm length by a factor of 50 to 150 km. The initial version of VIRGO operated from 2007 to 2011 and the facility currently is being upgraded with a new, more sensitive detector. VIRGO is expected to return to operation in 2018.

You can find much more information on VIRGO at the following link:

Germany: GEO600

GEO600 is installed near Hanover, Germany. It, too, uses a Michelson interferometer with arms that are 600 meters long, with resonant Fabry-Perot cavities that double the effective arm length to 1,200 meters.

You can find much more information on the GEO600 portal at the following link:

Japan: KAGRA Large-scale Cryogenic Gravitational Wave Telescope

The KAGRA telescope is installed deep underground, in tunnels of Kamioka mine, as shown in the following diagram.

img_abt_lcgtSource: KAGARA

Like the other facilities described previously, KAGRA is a Michelson interferometer with resonant Fabry-Perot cavities. The physical length of each arm is of 3 km (1.9 mi). KAGRA is expected to be in operation in 2018.

You can find much more information on KAGARA at the following links:


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

Peter Lobner

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?

Peter Lobner

Updated 14 December 2019

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 background information on Kurzgesagt, visit their website here:

You’ll find their YouTube channel with a library of briefings at the following link:

Form here you can navigate to many intriguing and entertaining animated briefings.  Four Kurzgesagt briefings address the following questions regarding extraterrestrial life:

“The universe is unbelievably big – trillions of stars and even more planets. Soo… there just has to be life out there, right? But where is it? Why don’t we see any aliens? Where are they? And more importantly, what does this tell us about our own fate in this gigantic and scary universe?”

I hope you’ll enjoy these Kurzgesagt briefings:

The Fermi Paradox — Where Are All The Aliens? Part 1:

The Fermi Paradox — Where Are All The Aliens? Part 2:

The Great Filter:  Why Alien Life Would be our Doom:

Aliens under the Ice – Life on Rogue Planets:

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

Peter Lobner

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

Peter Lobner

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

Peter Lobner

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

Peter Lobner

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

Peter Lobner

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

Peter Lobner

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: