Blog Index for June 2017

Nothing escapes from a Black Hole, yes? That means it's impossible to take a picture of a black hole because the photons you'd capture for the image cannot escape the black hole. Therefore, how do you take a picture of a black hole? Astrophysicists are working on a system to sort-of take such a picture. They've observed orbits of stars at the center of the Milky Way Galaxy, and deduced there must be a super-massive-black-hole. How do they verify this assumption?

While one cannot take a direct picture of a black hole, there is supposed to be (according to Einstein's Equations) a big light show at the Event Horizon. Imaging THAT for the Milky Way's super-massive black hole would require a telescope the size of Planet Earth.

A telescope that size isn't practical. Instead, Astronomers are piecing together a large telescope by slaving together radio-telescopes around the planet, and using computer-aided-image-analysis to put together the whole picture. The effect is a virtual telescope the size of the planet. They expect to have the first images later in 2017.

A key in the effort is to not prejudge the content of the images. They can't just program Einstein's Equations into the image processing algorithms, because that would just give them the images Einstein predicted. Instead they need to remain open to any possible result, and then be pleasantly surprised if the result confirms Einstein's predictions, or to learn from the result if they do not confirm the prediction.

Connecting to a remote computer is very powerful, because you can access remote files, remote applications, and so forth. Those of us building home automation or other Internet of Things devices sometimes install those devices at a remote location behind a NAT firewall, and then need to access the computer's desktop environment. For example, I have a Beaglebone Black at a remote site over 3000 miles away, and needed to run Firefox on the BBB to access some things. It's not feasible to go to the device in person, therefore the question is how to access the remote desktop.

VNC is the primary choice for this purpose. It has a lower bandwidth requirement than running X11 over the Internet, plus you avoid the complexity of installing an X11 server on Windows or Mac. Simply install a VNC client, instead. The key hurdle is getting past the NAT router.

Colossus was designed during World War II for one purpose -- decoding top secret encrypted messages sent by Germany using the Enigma Machine. Germany thought their messages were safe, but the Allies had cracked the code using these computers, and were therefore able to win the war. The Colossus was purpose built, is not a general purpose computer but instead performs a specific processing task. Several instances of the Colossus was built during World War II.

The Harwell Decatron was designed to automate mathematical computations which it did for several years.

The PiKon Telescope combines the Raspberry Pi, some PVC drain pipe and a few 3d printed parts to become a high power telescope capable of some impressive astrophotography. This video goes over building the thing. A primary problem is that the official design uses a type of PVC pipe easily available in England, with a 5" diameter, that isn't available in the USA. You can order a kit of parts from the fellow in England.

The design is a reflector telescope, meaning that a key component is the Mirror assembly that fits in the back of the tube. At the other end of the tube is a "spider" that holds the PiCamera and handles the focusing.

It uses a regular PiCamera with the focusing lens removed. Focusing is handled by moving the camera assembly back and forth.

What are the best linux-single-board-computer's? There are many of these things, and running linux on a tiny computer is awesome, but the wide variety makes it difficult to choose. Do you go with the Raspberry Pi just because it's the most popular? Or because your buddy down the street got one? Some of these computers have significantly important features giving a clear advantage for certain purposes.

Google makes a lot of money off of Internet advertising. Advertising services are Google's main income stream off which they've built a humongous business. There are lots of crappy abusive advertising practices on the Internet, and Google plans to change Chrome to block some of that advertising. It's important therefore to question whether Google's plan to block some advertising is legitimate.