Copasetic Flow

I'm in the process of reading Schiff's Gravity Probe B inception paper[1].  Gravity Probe B was the satellite borne experiment that detected the Earth's gravitomagnetic field, but that's not what I'll be talking about today.  This post is more about a math trick/pattern.  It's a mathematical pattern that comes up pretty frequently in physics, so I figured it was worth a few notes here.  The first picture below shows the equation for the torque on a spinning object due to a spherical source of gravity, (like the Earth), with a bit of its attendant explanation by Schiff.  My notes can be seen to the left: The cool part I'm going to focus on today is one of the smallest expressions within the rather ginormous equation 3, (also shown in picture 2): $$\left(\vec{\omega}\cdot\vec{r}\right)\vec{r}/r^2$$ I've run into structures like this in the past and it took me awhile to realize what they did.  Likewise for some of my classmates.  The short versio...

While doing research for an article I'm writing about Janet Tate and her Gravity Probe B experiment[4], I found a few cool things regarding superconductors, frictionless bearings, and the Egg of Columbus experiment this morning. The Egg of Columbus demonstration was first performed by Nicola Tesla in 1893 at the World's Columbian Exposition [1].  Here's a brief video from MIT showing a modern day version of the demonstration[2]: The MIT site[2] describes the apparatus as follows: "A toroid with three different wire windings is connected to 220 VAC 3-phase voltage. The voltage phase of each of the three windings lags 120 degrees behind the next, creating a changing induced magnetic field. The changing field causes metal objects to rotate when placed inside. Motors using this principle are very common. In fact, power lines are often seen in sets of three because they are carrying three phases. For more information on 3-phase voltage," Alfred Leitner made ...

Faced with students that didn't quite believe Newton's law of gravitation, Anthony Rennekamp  of Bishop O'Connell High School in Arlington, Virginia, he did what any physicist would do; he had his students build an experiment.  They created a version of Cavendish's experiment using two yard sticks, two one kilogram weights, and a few 50 pound dumbbells.  You can find the write-up of the experiment on the Physics Today website [1].  Mr. Rennekamp and his students also made a video of the experiment.  Given the slow velocities with which the masses move in this experiment, the class reasoned that speeding up a video was the only practical way to view the results.  They published their experimental results video on youtube, (you can watch it below).  There was some online disbelief that the experiment could work as well as it apparently did.  I thought it would be fun to just run a few back-of-the-envelope calculations here and see if their results ...

Michael Heiland serendipitously took this phenomenal time lapse video of the pink space cloud reported over Arizona last week on 2/25/2015. The cloud was formed by the Air Force Research Lab's rocket-launched ionospheric research experiment .  The video was taken from Michael's perch on Mount Lemmon northeast of Tucson. Based on the timing of this video showing the appearance of the cloud pretty much coincident with sunrise, the two science questions remain unanswered. Did the substance released in the experiment react chemically with the sparse oxygen in the ionosphere causing a glow in the process, as in the first Smoke Puff experiment back in 1956[2]? Or, was sunlight responsible for ionizing the substance in the same manner as the phosphorous payload released in the Smoke Puff 2 experiment[3]? +Michael Heiland  is a bit of a phenomenon himself.  He became famous for a gorgeous  time lapse video of the Phoenix valley  he made as a high sc...

A pink cloud was reported in the early morning, (pre-sunrise), sky over Arizona on Wednesday [1]. NASA and the DOD soon thereafter took credit for the cloud.  They had launched a rocket into the ionosphere where it released a vapor that created the cloud.  The purpose of the experiment was to study the effects of the vapor on the ionosphere itself.  The article, referenced above from ABC, said: "The experiment, which also involved using ground stations to take measurements of the ionosphere, was intended to develop scientific explanations for ionospheric disturbances and their effects on modern technology, officials said." This has all been done before [2] as it turns out!  In 1956 the Air Force launched two missiles from White Sands Missile Range with payloads of nitric oxide.  The gas released in the ionosphere created a glowing cloud described as being ' yellow-red '[3] in color.  They were studying the ionosphere as well, which, back in 195...

Did you ever wonder if there was any 'real science' behind the subject matter of shows like 'Ancient Aliens'? There is! Yesterday I came across these two articles[1][2] by Dr. Virginia Trimble: UC Irvine astronomy professor and science historian. The first article was written by Dr. Trimble when she was still an undergrad at UCLA. It detailed her calculations showing that the constellation Orion was visible through the 'so called air shaft' of Cheops pyramid when it was constructed. The second article was an excellently written and fun to read review of the a 1979 "Symposium on the Implications of Our Failure to Observe Extraterrestrials " The symposium was attended by luminaries such as Freeman Dyson and Bracewell. Among other topics, there were discussions of how many planets were available that could support life. It gives a nice historical perspective on today's post from John Baez [3] References 1. "Astronomical Investigation Conc...

Work is proceeding on testing the systems that will be used in the experiment.  While the glass Dewar’s silvering blocks gamma radiation in the 22 keV range substantially, it fits nicely inside the yoke magnet whose field can be easily measured.  A temperature gauge was located; vacuum testing was started for the inner Dewar and lid, (including the instrumentation ports.)  Scroll to the bottom for the background of the experiment. All about the temperature gauge Today, just pictures of the gauge.  For an idea of scale, its rectangular footprint is about the size of a nickel.  The four wire sockets on the left are for attaching a four point probe to measure the resistance of the gauge. The Dewar lid with all the attachments The easiest way to seal the Dewar lid was to put the instrumentation stick back in place.  An experimental stage to hold the Pb sample still needs to be designed. Testing the vacuum pump before testing the D...