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Blog Entries posted by running_dry

  1. running_dry
    The second major type of telescope is the reflecting telescope. The reflecting telescope was invented by Newton and considered an improvement on Galileo's design. Most reflecting scopes still use Newton's design. Reflecting scopes use a wide concave mirror at the back of the tube to bring light to a focal point in front of the mirror which is then usually reflected sideways toward the eyepiece by a flat, angled mirror. There are also compound scopes that work like reflecting scopes but there is a hole in the center of the concave mirror and the mirror at the foal point reflects light back through the hole where it is magnified by an eyepiece at the end of the tube. Below are diagrams of both reflecting and compound telescopes.

    Now for some pros and cons. Refractor tubes are usually longer and skinnier, thus have smaller apertures (and cost more per unit of aperture length); while reflectors are wider and shorter with larger apertures (and less cost per unit of aperture length). Because of this, refractors are usually more expensive and better for observing close planets while reflectors are better for observing deep sky objects like galaxies and nebulae.
  2. running_dry
    Kickstarter is full of cool stuff but a project called Altergaze really caught my eye. What it is is a 3D printed platform with a set of up to 3 lenses inside and a holder for your smartphone. The lenses magnify the screen so that it takes up your entire field of view, allowing you to watch video and whatnot in giant, beautiful panoramic views. And the beauty of it is that since it it 3D printed, the firm starting it is making the templates open source and offering partnerships to just about anyone with a 3D printer. They supply the lenses but you get to choose colors and can modify the phone holder to accommodate any kind of phone you want. You can check out their kickstarter page here: https://www.kickstarter.com/projects/278203173/altergaze-mobile-virtual-reality-for-your-smartpho?ref=category

    The physics comes in with the lenses. The lenses magnify and bend your field of view by refracting light in such a way that makes your phone's screen everything you see.
  3. running_dry
    I just found a video of a man playing a Tesla coil as a musical instrument. With a guitar. Basically, the guitar still works the same way but rather than sending its MIDI signals (notes and such) to an amp, it is being sent to a Tesla coil. Tesla coils work by sending alternating current through a wires coiled into a torus (donut shape). The changing current charges a larger torus trough electromagnetic induction. The voltage induced in the second coil is much greater than the first which allows a capacitor to be charged to the extreme where it trows visible electricity to the nearest conductor. When the coil is turned on it makes a noise, so the trick to making music with a Tesla coil is to alternate current at a frequency at which our brain can interpret music (it turns out to me about 440 hertz). Notes can be created by modulating the amplitude of the current. In the case of the guitar, the players input on the strings is used to modulate the amplitude. Here's the video i was talking about:

    And then I found this and my mind was blown...

  4. running_dry
    I would like to take a step back from physics to propose another law on the effects of procrastination on the APlusPhysics blogs. I have already explored the relationships between amount of procrastination and both quality of blog posts and hours slept the night they are due. Every time I refresh the "dashboard" page five new posts pop up, and I have noticed that the same posts don't stay on the front page for very long. It would seem that we are all hurting ourselves in terms of views by all waiting until the last possible second to do these because in the time that it takes to write the next post, your last post has already disappeared, never to be seen again by anybody. On the other hand increased site traffic might expose your blog to more potential readers. All of this of course really only matters if you care about how many people read your posts (I do, just because I take the time to write them). I could also be mistaken about how the dashboard works....
  5. running_dry
    In December of 2013 physicists discovered a way to approximate the amplitude of scattering sub-atomic particles in a way that is much, much simpler than the old method. The idea is that given a set of parameters and whatnot, a geometric object, which is being called an amplituhedron, can be constructed such that it's volume equals the amplitude of a scattered particle from a quantum interaction. The old method involved using hundreds to millions of Feynman diagrams, which show possible ways the particle could scatter, and summing the probability of each situation occurring. Even a simple interaction had to be modeled by a formula several billion terms long but the amplituhedron process reduces that to just a few pages of work. For example, the diagram to the left represents an 8 gluon particle interaction. If the same calculation were to be done with the Feynman method it would involve around 500 pages of calculations. The implications of this are enormous, and this may be a big step in the direction of a functional unified field theory.

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