Copasetic Flow

We've been trying to decipher the video upload system for Google+ events over at the  +STEM on Google+ Community  share your story event.  It's messy and doesn't work as you might expect it to on first glance.  The short version of the story is this: 1.  You can upload videos into events, but it seems they have to be encapsulated in albums that already exist. 2.  You won't see the video in your album, but go ahead and add the album to the event anyway. The video will be added. 3.  Each photo in 'Photos from Posts' is its own album.  Consequently, the easiest way to share a single video to an event is to first share it to your stream to get it into the 'Photos from Posts' album and then, add the video to your event from there. Gory Testing Detail Now, here are all the gory testing details so you know what we saw and also so you'll know you're not going crazy when you run across these problems. OK, here's the latest.  I tried to do...

Rindler demonstrates[2] the best way ever to derive the relativistic Lorentz contraction/time dilation factor, gamma, (of twin paradox fame), from four velocity!  I've been working through Rindler's paper on hyperbolic motion as a result of constant acceleration[1] lately. Starting from the constancy of the speed of light, Einstein's theory of special relativity posited, and Minkowski refined the idea that the universe is actually four dimensional with space and time sitting on an equal footing.  Starting from here, we can write an expression for the distance squared along an infinitesimal line element in four dimensions, (think Pythagorean theorem)... Brian Greene popularized the idea of four velocity[3] in one of his books and although it isn't mentioned as much as some of the other aspects of special rel, it's a simple idea.  Everything is moving at the speed of light.  Something might have more of it's velocity pointed into either the space dime...

The ongoing series of posts on cool places related to STEM: Today.. Hyderabad! I was called to Hyderabad, India a few years back in my alternate guise as an electrical engineer.  I'd just spent a week making presentations in Nice, France, (more on that later), and my boss called to ask if I could make it to Hyderabad in two days.  I hustled up to Paris and spent the day outside the Indian consulate trying to get a visa.  After a few meetings, I was able to get ahold of one and off I went. Hyderabad is the fourth biggest city in India and plays host to Advanced Micro Devices, ATI, and Xilinx among other semiconductor companies.  It's a huge and vibrant city with a bit of a traffic problem. but not to worry, everyone here ride shares. In case you missed anything, there are four people on the motorcycle.  I haven't been allowed to try this with Jr. yet, despite my assurances that it's perfectly safe. I was able to sneak away via auto-rickshaw one af...

For what's going on with research, scroll down.  But first, another study topic for the amateur radio extra class exam.  One of the questions asks what the purpose of a sense antenna is.  The correct answer is that "It modifies the the pattern of a DF antenna array to provide a null in one direction."  Whatever that means.  The DF referred to in the answer is direction finding.  Small loop antennas, like the one shown in the picture to the left (picture 1), can be used to find the direction that radio signals are transmitted from.  By rotating the loop until the received signal becomes the weakest, you can locate the direction.  There's only one problem, you can't tell whether the signal is coming from in front of, or behind the loop.  This is where the small vertical antenna in the picture comes in.  That's the 'sense antenna' or 'sense aerial'.  Its signal is added to the signal of the loop antenna and the net result is tha...

If you're coming in from the physics side In my spare time I write web apps. I also play with ham radios as KD0FNR.  One of the web apps I've published provides practice exams for ham radio license tests.  What follows is a study video for the extra class exam.  The extra class license is the highest class of license an amateur operator can earn in the United States and the test requires quite a bit of electronics theory. If you're coming in from the ham radio side For my full time gig, I'm a graduate student in the physics department at Texas A&M University.  In my spare time, I write about physics topics that catch my eye on any given day. Now for the study video This study topic details how to work through the questions on the exam that ask about the phase relation between voltage and current in a series RLC circuit.  It shows a few tricks for doing the problems without a calculator.  All feedback is welcome.. please!  As for me, I feel t...

As the third week of the short summer session for freshman electromagnetism opens, the minds of young professors everywhere run towards cool polarized light demonstrations.  In helping track some of these down, I remembered that there was an awesome experiment involving sodium chlorate in a book titled "Crystals and Crystal Growing" by Alan Holden, Phylis Morrison.  It turns out that sodium chlorate crystals pass polarized light at different angles depending on the wavelength of the light.  In short, if you place a sodium chlorate crystal between two Polaroid sheets, and then rotate one while keeping the other still, you will see the color of light passed though the crystal change, (picture1)[1]. Detail of the Experiment Since I don't have time to grow a crystal, I thought it should be easy enough to find a video of the experiment  on the internet.  So far, I've searched to no avail though.  So, here's the challenge... Can anyone provide a...

Happy Fathers Day everybody!!! In honor of Fathers' Day, here are a few physicists who had kids that went on to become scientists themselves.  I know there are far more examples than I've listed here.  Feel free to add your favorites to the comments below! William Fairbank and William Fairbank Jr. William Fairbank Sr. performed one of the first two experiments that verified the existence of quantized magnetic flux[6].  He was also one of the architects of the Gravity Probe B experiment.  His son, William Fairbank Jr. is a physicists at Colorado State University who works on the detection of single atoms via photon burst mass spectroscopy (PBMS)[7]. Another one of William Fairbank's sons, Richard Fairbank, founded Capital One Bank which provided the last bit of funding so that work on Gravity Probe B could be completed after NASA quit funding it in 2008. Sydney and Persis Drell Sydney Drell proposed the Drell-Yan hadron scattering process in 1970. ...