Well the weather this week has been more cloudy than not and so again I have postponed taking the wheeled tripod out for a spin and observing session. The forecast for good skies has been pushed back a couple of days now, but at least tomorrow night is supposed to be very clear. In the meantime, we will cover some news, some preparation for the eclipse and go over some of the progress in astrophysics study groups. So, to get started we watched on the morning news, an event that was in my previous life a source of considerable planning and work and that
event was the commissioning of the USS Gerald R Ford. Years ago,, I spent a lot of engineering time trying to develop products and develop teams to develop systems for installation on the new carrier construction. I worked on trying to develop five major systems but none were selected at the end of the day. The biggest system was for electromagnetic launching of aircraft and our team made many studies and proposals, but unfortunately did not survive the down select. Anyway, it's good to see the winning system finally installed and ready for sea, but that is part of my previous life and now I'm just journeying forward as a physicist and astronomer wannabe.
|USS Gerald R Ford, ready for commissioning (Source: US Navy)|
But, back to the present, and speaking of testing of new products, our friends at Amazon just dropped of the new lightweight, airline luggage compatible, chair, that we described in last week's blog post. We plan to bring this chair with us to Casper. As we have said before, our observing location there is not known and we are planning to bring at some creature comforts for our hours out in the sun just in case we find ourselves set up far from the car or the hotel room. So, we unpacked the chair and tried out the seat and back support and even got unasked for help from the Astronomer Assistants, Ruby and Danny.
|Resident Astronomer testing eclipse viewing chair with help from Astronomer Assistants, Ruby and Danny|
|Can we remember how to use our ham radios during our eclipse travels?|
Other news this week is from Ethan Siegel in his Starts with a Bang! website where he posted an interesting perspective on unusual photos to take during the eclipse. You can find that post and others on his blog site listed on this blog site front page. The screenshot shown below shows one photographers image of the sun and solar wind, and the interesting feature of this photo is how the moon itself, is illuminated by light reflected from the Earth's surface. I like that and intend to try to capture an image like that too! So the moon gets in the way of the sun and yet manages to show enough of itself to be photographed.
|Wow, imagine taking an eclipse photo and imaging the moon at the same time (Source: Ethan Siegel: "Starts with a Bang")|
Finally, since we haven't done any real observing this week, I wanted to review the status of how some of the free internet physics classes are going. For all of you budding astrophysicists who have already signed up for the edx course, "Astrophysics: The Violent Universe", you will already have worked out some orbits and luminosities for a binary star system and will be aware of the special homework problem that is one of the fun parts of the free internet course.
The instructors setup an imaginary situation where each of us gets to pretend to be an astrophysicist and they begin with the scenario and try to decide what data should be collected and analyzed to solve the problem. In this case the situation is to pretend you are located on a different planet, a planet that does not have a sun and is surrounded by enough bright stars that the whole planet is illuminated all the time. There is no day or night. Think of this as a real example of Olber's paradox where the stars themselves provide all the light on the planet. How can science get started and move forward in this imaginary world without the examples of planetary motion to inspire Newton, Galileo, Kepler and others from antiquity?
Anyway, the beginning scenario continues with just one strange object seen in the sky, from one location on this planet, and that is the Pillar of Flame as shown in the screenshot below. So what series of observations do you want to schedule in order to begin to understand and answer what is this strange light in the sky. For instance we will want to observe the Pillar of Flame and see if it rotates with the stars or with the planet or if any rotation is detectable at all.
|Screenshot introducing special homework problem (Source: edX course, Astrophysics: The Violent Universe)|
So, go out and get signed up. Each week we will get one extra clue and will have to work out what it means and what additional data we should seek or what observations we should make. It's free and looks like it is going to be educational and fun.
The 2nd course of study is the Quantum Optics course from www.coursera.org which is in its sixth week and I am way far behind. It just got to be a little to difficult for me to follow. How many of you signed up for this free course and how is it going? Well, I'm learning a lot and find that quantum optics is a great way to learn more quantum mechanics and actually get to do calculations that apply to real world experiments. One of the neat things I am getting out of the course is that even though popular accounts of quantum mysteries, such as the double slit experiment and the single-photon interacting with itself and the wave-particle duality puzzle are still experienced as mysteries by real physicists but at the same time they know how to apply quantum logic and are able to calculate what can be observed in real experiments that involve all of those puzzling aspects of reality. It is how to set up the calculations that this course deals with and once you start to get involved with that and can do the calculations yourself, you see that even though the puzzles remain, it does not bother you because you can calculate and predict how the experiment will turn out.
I picked one video frame from the course as an example, which demonstrates how single photon sources are evaluated and can be detected and how quantum logic differs from classical logic. For classical light waves, without any correlation, the probability of coincident detection is just the product of probabilities of a photon either being transmitted through a beam splitter or being reflected at the beam splitter. This type of setup is used to verify that the light source coming into port (1) of the beam splitter is really just a single photon at a time. Now later on when we set up the calculations for photons entering an interferometer or double slit setup we can calculate how the single photon can interfere with itself. So, even when this doesn't seem to make any sense and is considered a mystery, I hope to learn in the coming weeks how we can calculate what the results of the experiment will be and quantum mechanics is shown to be valid every time.
|Screenshot from Quantum Optics course demonstrating single photon anti-correlation (Source: www.edX.org)|
So, even though I am quite a bit behind in the course, I am still plodding along and continue going at my own pace Luckily, I have a couple of other associates who are going through the course at the same time. I find it quite neat to be able to almost right down the equations for some of the popular physics puzzles and be able to calculate and get the right answer without being tied up in wondering why the world is like that.
The final study area reported on at this time is the ongoing study of gravity and general relativity. I am lucky here again to have a group of a half dozen or so "senior scientists" or "physicist wannabes" to help out when the going gets tough, which is has been. I thought that with my engineering background I had a pretty good mathematical background, but it turns out to do general relativity, you need a lot more math, especially in terms of tensors and tensor calculus. Tensor equations enable a mathematical way of tying together the curvature in space time to the amount of mass and energy and describing how to calculate effects. Anyway we have been making our own progress in understanding gravity as described by general relativity. I find that trying to tackle a subject like general relativity on your own is very difficult and it is good to have other interested persons going down the same path, which helps but my sense is that it would have been much easier if I had just had this subject as a regular class with instructor and recitation sessions.
Anyway the study continues. Studying general relativity is so necessarily a part of astrophysics and cosmology. Take a look at it some time and see what you can make of it.
Good seeing tonight. Until next time,
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