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Making a tachometer for a grinding / polishing machine for telescope mirrors

When making a telescope mirror on the machine, two parameters are important: the rotation speed of the mirror, and the rotation speed of the overarm eccentric. Other environmental parameters also matter: temperature and humidity are foremost here. To more easily monitor and display these variables, I've built an electronic device that collects this data and shows it on the control panel. This is how to build the device.

Massive scalability when querying metrics stored in Graphite

Is your Graphite backend not fast enough for either receiving metrics, or querying, or both? Split it up for a massive performance boost.

multifactor authentication for distributed VPN mesh - part 3, VPN mesh

One VPN server not reliable enough? Create more than one, and connect them together.

multifactor authentication for distributed VPN mesh - part 2, token configuration, local OTP

Running a VPN server with OTP? Thinking to run your own OTP authentication backend, instead of the public backend? This is how to do it.

multifactor authentication for distributed VPN mesh - part 1, server and client configuration, cloud OTP

Building a distributed VPN mesh (multiple VPN servers, authenticating same accounts, having same routing)? Want to give a security boost to authentication? Thinking about multifactor? Here's one of the many architectures that work.

Easy multifactor authentication for SSH using YubiKey NEO tokens

Here's a way to improve the security of your private SSH keys using a cheap smartcard.

Monitoring for the cloud, part 2 - architecture

There's a cornucopia of tools for monitoring cloud infrastructure: Sensu, Graphite, Logstash, Riemann, etc. The very, very good news is that most of these tools speak each other's protocols. This opens up a lot of possibilities: from small setups where some components (e.g. the message queue) are reused, serving many purposes at once, to complex architectures where the various functions are decoupled, there are large amounts of redundancy at various levels, etc.

Monitoring for the cloud, part 1 - tools and techniques

Moving your infrastructure into the cloud, or thinking to do so? Still using old monitoring tools such as Nagios and Munin? There's trouble for you on the horizon. But there are better ways to do monitoring in the cloud - read on to find out.

150 mm f/8 mirror (25 mm Pyrex) Polishing and figuring log

Just a quick link to the polishing log for the 150 mm parabolic mirror:

How to see Sirius B

Sirius is the brightest star in the night sky, visible anywhere on Earth except the far North. If you live in the northern hemisphere at a temperate latitude, Sirius is that very bright white star due south every winter in the evening. But did you know that Sirius is also a double star? The companion, Sirius B, also known as The Pup, is a very small star orbiting the primary, and can be seen using amateur telescopes, even small ones. It's not an easy observation to make, but it can be done if you follow certain guidelines. Here's how to do it.

How to make Halloween creepy blinking eyes with an ATmel AVR microcontroller

An ATtiny2313 chip, some C code, a bunch of LEDs and other components - that's your DIY Halloween decoration this year. I'll show you how to do it, and there's a video at the end of this page showing the digital creepiness in action.

I had no idea just how big the Solar System really is

So, we did a "science project" today, the kids and me. We made a scale model of the Solar System, out on the street, to get a visual impression of its true size. It was pretty amazing. It's a very easy project to do, takes a couple hours, and it's a lot of fun.

On public roads, profiling other drivers can be a good thing

A few years ago I bought a motorcycle, and quickly discovered the necessity of trying to predict other people's behavior on the road - profiling, basically, not for the sake of it, but in the interest of my own safety. On a bike, the main source of trouble is not yourself, it's other people. Also, on a bike, trouble is either absent, or very very big. So I started to collect these observations - and continued to do so even later when driving my very boring and average four-wheel sedan.

These are not inflexible rules, but merely "statistical truths". I do think the observations are sound, so I use them all the time as guidelines. Here's the list:

How to build a small laser that can burn things

It used to be that lasers were big bulky expensive things that required a laboratory to run and an entire factory to build. I remember the first He-Ne laser I saw two decades ago, the size of a small telescope and probably not more powerful than the laser pointer I carry on the keychain nowadays. Well, not anymore. It's pretty easy to build a laser today, on the kitchen table or in the garage, for a surprisingly small investment. The goal is to make a laser capable of burning small objects, such as a piece of paper, a balloon, etc, while keeping the whole project cheap - even as cheap as $35 if you don't make any mistakes. Here's how.

Bye-bye cable news

Finally got rid of cable TV today (actually Mihaela did, it was her initiative). Renting movies on Netflix is quite enough, even more so if you consider that you can do video streaming from Netflix directly to the PS3. What with their tens of thousands of titles, I'll never run out of movies to watch. Kids get their cartoons too from the same source. Plenty of fish in that pond.

I bench pressed 100 kg (220 lb) today

Goals - we all have goals. Some people's goals are pretty lofty - make a million this year, or ten, or climb the Everest - and sometimes they even achieve them. Others have more modest ones. Mine was to bench press 100 kg (220 lb), and I achieved it today. Here's the blow-by-blow.

"Zeitgeist", the movie, debunked (part 3)

This is the third part of the review. The second part is here:

"Zeitgeist", the movie, debunked (part 2)

This is the second part of the review. The first part is here:

"Zeitgeist", the movie, debunked (part 1)

I had no intention to write about "Zeitgeist" at all. I've skimmed it shortly after its release, seeing as it had generated a pretty consistent buzz on the blogosphere and the discussion forums. I've seen references popping up here and there afterwards, but mostly I just ignored them. So I thought the whole affair was dead and buried and I was well on my way to forget it. Except, I was not aware of the impact and influence that the movie still had in the time that followed - and still has today. That was my biggest surprise, and the reason why I'm writing now.

OK, I'm lying. I'm also writing about it because I need the exercise - you know, to keep that pen sharp, or rather that word processor busy. But regardless of the reason, here it is, my review. Sort of.

Politics and the brain - an attempt at understanding a divided America

A constant theme of the American politics in recent years (the '00 decade), at all levels, is the great and apparently increasing polarization of the political spectrum. Politicians talk about "partisan politics", and if you look at the number of votes in Congress neatly divided on "party lines", as if mindless robots are casting the votes, not living human beings, you understand these are not empty words. Commentators and pundits have observed an increasing tendency of some neighborhoods to become "unicolor" politically, as if there's some selection mechanism pulling diverse people apart. Changes happen at the high levels of any of the three branches of government and then people talk about that saying how they need to "get their country back" or how they just have gotten it back, as if an invasion has happened at some point and some foreign or alien force has taken over or has been defeated. And finally the media, supposedly neutral, allegedly existing just to inform citizens about events, seems to be shifting towards more partisan positions.

It is perhaps easy to dismiss these things as being just "politics as usual" - and maybe that's the case, at least presently. But this is not a random universe and things tend to happen for a reason, and when you observe trends which are this large and deep and persistent, you are entitled to start looking for a cause. It is this way because something caused it, and trying to find an answer to the question "why?" often sends you off in directions which are as surprising initially as they are satisfying (from the point of view of knowledge) in the end.

The thesis which I am advancing here is that the seemingly deep division in modern American politics has come to pass because this is a scene with two main actors - the two major parties - whose positions have slowly changed over many decades until they have stumbled upon two great attractors in the field of human psychology, and now are stuck. It's essentially the supremacy of psychology over politics, certain features of the human mind acting as mooring posts far from each other, preventing not only any further drift, but also most attempts at bridging the gap.

Let's begin with looking at the way the human mind works, using the triune brain theory, Transactional Analysis, and related models - the clues we'll find there will make the explanation pretty obvious.

Review: "His Dark Materials" trilogy - "The Golden Compass", "The Subtle Knife", "The Amber Spyglass" by Philip Pullman

An epic fantasy trilogy, the first part already a movie ready to launch on December 7th:

The interesting part is the amount of noise the movie has generated in the media, despite the fact that the three books were not as controversial, not even close. But why the controversy?

Game review: "Bioshock", by 2K Games

Bioshock is a first-person shooter game, released in 2007.

The plot follows plane crash survivor Jack, as he enters and explores the underwater city of Rapture, the goal being survival and finding a way out of the city. The game looks and feels like a morality-based Doom, of sorts, but the story has surprising and fascinating connections which are not obvious at first sight.

The quest for intensity

This is a follow-up to my essay "The decision tree" which can be found here:

You're riding the sportbike on a technical road or track, quickly following the riders ahead of you, braking to shed speed, leaning through the turns, straightening up the bike, revving the engine until it's screaming with rage and joy, and you're propelled forward by the awesome acceleration of the racing bike, and you do it over and over again, until every fiber in your body is vibrating with the thrill of the extreme speed and the world disappears in a fast receding blur.

The decision tree

This is the follow-up to my essay "The engines of joy" which has been published here:

This time I will examine the same themes, but from a different perspective.

Movie review - "300" by Zack Snyder, based on Frank Miller's graphic novel

This is not the usual run-of-the-mill historically accurate movie. Those who expected that were surely disappointed. Instead, the movie chooses to stay faithful to the graphic novel by Frank Miller. So, it's a mix of stories of bravery and honor, of Miller's intense imagery, and of post-Matrix cinematography. The results are very interesting indeed.

Keep reading to find out why.

The engines of joy

On January 9th 2006, while riding my motorcycle to work, I had an accident. I thought the car ahead of me in the left-hand lane was going to swerve into my lane. That was not true, but I acted upon this false impression and I hit the front brake hard. The front wheel froze, the tire lost traction, the bike fell on the left side. I hit the road and tumbled a dozen times or more. The bike was a total loss. I was rushed to the hospital - the result: broken right ankle, broken left collarbone. I underwent surgery to fix my ankle, which put a metal piece in my foot and several screws to keep together the shattered bones. I had to do many months of physical therapy to recover the ankle, which may or may not be ever the same - it's too early to tell now, about 9 months later, although I made huge progress and the prospects look good. My own god damn fault, this whole affair, but that's not the topic of these pages.

And yet, one of the things I often - nay, I permanently dream about is to get back in the saddle. Keep reading to find out why.

Movie review: "Fearless", with Jet Li

"After a great war, foreign powers ruled China. But our traditions still gave us hope. To break our will, they staged the tournament to prove the superiority of their warriors against our own. Only one rose to challenge them. He carried our pride on his shoulders and brought the nation to its feet."

"This man was fearless."

This is a movie with a very high charge, a dual charge - it is the expression of a certain ideology and, at the same time, it carries the story of extreme transformation through extreme challenges of destiny. Click below to read the full review.

Movie review: "Troy" by Wolfgang Petersen

Official site and IMDb page:

The greatest battle of the antiquity. The greatest heroes. The greatest story.


Read on for the full review...

Only human

I just watched "Borderland", an episode in the 4th season of the Star Trek Enterprise series. As the new Star Trek goes, it's pretty good. We get to see Brent Spiner again, there's lots of action, the plot - albeit not too original - is pretty well guided and has good rhythm... And yes, it's the "beyond humanity" theme again. And it's the same old comfortable yet cowardly answer to it again. Let me explain.

Movie review: "Alexander" by Oliver Stone

Official site and IMDb page:

Oliver Stone makes me feel uneasy. I think "Natural Born Killers" is a gratuitous parade of violent content, with no message worth the bother. I kinda shrugged at "Any Given Sunday" - again, gratuitous violence and no message i could care about. "JFK", "Born on the Fourth of July", yeah, those were cool. "The Doors" - one of the most ambiguous movies i've ever seen, i love it as much as i hate it.
And here comes this new movie, "Alexander". I went to see it mostly because the music is made by a composer i admire - Vangelis. I went there kinda prepared to listen to the music on the background of the movie :-) as it were. I came out thoroughly impressed by the whole thing.
I love this movie. I don't care what the critics say. I just think it's great. Read on to find out why.

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