Disclaimer: Don’t look at any bright light source. It may damage your eyes!
The sound of a fly buzzing meant one more thing for me to before going to bed. What happened next took me by surprise and provided some fascinating entertainment that I thought I’d share with you.
Returning from the kitchen with a can of fly spray, I heard it’s intended target was in the last remaining light source in my house – the big orange lampshade by the couch. After peering down into the lampshade and releasing a couple of light sprays I returned to the darkened kitchen only to notice I was seeing spots, three large overlapping ones to be precise.
These black Venn Diagrammesque apparitions were due to photobleaching of the chemicals my eyes use to sense light. They were in three distinct places because the eye flicks quickly when scanning – if I had been watching a marble race I’m sure it would have been a circle.
Anyway, we’ve all see spots right? What was really neat was what I discovered next…
Covering my eye made the spots go a light colour. Looking at the pantry doors resulting in them being dark. The spots faded within seconds however covering my eyes brought them back, as did shifting my gaze to a different area in the room. I think I’ve found a new way to demonstrate perceptual filling-in. Until now I’ve only heard of blind spot fill-in.
The beauty of retinal burn fill-in is that you don’t need to find your blind spot, or be a certain distance from things as you can control where you place the burn. It’s amazing to watch the burn dissolve as the brain fills in the missing information. I’d advise against deliberately looking into any bright light source but next time it happens I suggest you use the opportunity to experience first hand the difference between the signals your eyes send and what you perceive.
I’m a massive fan of Vagrant‘s command line virtualisation goodness. This post is me trying to find a public place for my vagrant notes to rest (I couldn’t find a cardboard box).
This vagrant rubygem plugin automatically updates /etc/hosts on your guests and host box each time you run vagrant [up|provision]
vagrant-vbguest is a Vagrant plugin which automatically installs the host’s VirtualBox Guest Additions on the guest system.
Last Friday night I picked up my new Macbook Pro and thought it might be worth sharing my initial experiences. Coming from a late 2011 MacBook Pro with HDD I’m loving the speed and lighter form factor.
Mac OSX Mountain Lion demotes /usr/local/bin in path
Homebrew’s ‘brew doctor’ command warned me about my PATH.
Warning: /usr/bin occurs before /usr/local/bin
This means that system-provided programs will be used instead of those
provided by Homebrew.
It turns out /etc/paths has listed last /usr/local/bin. Ever since reading Dan Benjamin’s post, Using /usr/local I’ve been…erm…using /usr/local. I’d be interested to know why Apple made this change.
MacGPG2 can mess with libiconv
While on the topic of PATHs, you don’t want this in your PATH: /usr/local/MacGPG2/bin
For some reason this was the cause of me being unable to compile native extensions in the tiny_tds rubygem. GCC appears to have been grabbing that item and then finding /usr/local/MacGPG2/include/iconv.h which conflicted with the OSX installed version. (Brew tells me the package is no longer provided as OSX provides libiconv).
Of the five senses, the two I get most signal through are sight and hearing. Over the past few weeks I’ve been experimenting with the former and have made some interesting discoveries (or perhaps more correctly, rediscoveries). I have no qualifications in lighting or biological science but think it’s worth sharing my experiences and a summary of what I’ve learned. I’d love to hear from you (in the comments) if you find any of it interesting.
People’s sensitivity to their environment varies greatly. I think I’m on the more sensitive end of the spectrum and are more affected by:
- glare (halogen down-lights, car headlights in the rear view mirror)
- color temperature (evening computer use, walking into convenience stores lit by fluorescent lights)
- golden hour (first/last hour of sunlight loved by photographers and film makers)
- firelight (candle, oil lamp, campfire)
The Lamp Shop
As a teen I went through a phase of lighting candles in my bedroom. The light they produced created a different mood or atmosphere that I think most readers will relate to. A few weeks ago when walking home from the Melbourne CBD I came across a curious little lamp shop that would not have looked out of place a century ago.
T. W. Sands & Co has been selling oil and kerosene lamps for almost 100 years. They never switched to electricity! Inside they sell new and old lamps, as well as wicks, chimneys, oil and replacement parts. My curious mind lit up with questions – fortunately the staff have a detailed knowledge of the workings of the lamps along with the history of advancements in burner technology. In short, the Americans won the arms race with the 40 candle power Aladdin which is still in production today. This uses a thermoluminescent mantle that throws off a bright white light when heated by the burner. They’re so bright they require a shade to reduce glare and while great for a dinner table I prefer my flames naked.
Oil Powered Time Machine
I returned the next day to buy three different types of lamp for my 1880′s home in Carlton North. The house sports three rather impressive fireplaces that would have been the main source of heating when built. The mantle pieces seemed like an obvious place to put the lamps. They stand at shoulder height and are a foot deep which means the lamps:
- are in an optimal position to light faces
- illuminate the other things on the mantlepiece, creating a feature
- probably most importantly, won’t get knocked over by an arm or bag hanging from someone’s shoulder
This last point is important. A number of people expressed alarm that I was using firelight in my house, fearing an accident. While I don’t think lamp oil will burn on floorboards, a rug, curtains or other wick-like furnishing would be happy to assist and I could imagine many a housefire was started by a lamp. The clumsy and dim witted are probably better off in a fire free household. I’m confident I can manage it though. Already I felt like I was defending something that few would have worried about in the 1880s.
I decided to do a sort of Earth Hour on steroids, abstaining from electric lighting for a week. The experience transported me back to a time where the human experience of night time was very different to what we know today. For someone with little practical experience using firelight in a domestic environment I had to work things out for myself. This was interesting from a historical perspective but also led to me learning more about how our eyes work and the magic of night vision.
In some ways it felt like camping, perhaps because that’s the only time I experience the night without electric lights. For this experiment I had a control – the house as I used it before – so I could identify what elements of the experience were due to the lighting. This removed confounding variables like country air, a long drive and kangaroos.
Firelight Changes the User Interface of a Room
Back in the late 90′s Google replaced Alta Vista as the search engine of choice.
One refreshing change was the lack of distractions on the Google’s search page.
Modern home lighting is akin to flood lighting. The majority of homes have overhead lighting without dimmers which results in reflected (and lots of it) light being pretty evenly dispersed. Firelight is of lower intensity and so highlights things in close proximity. You wouldn’t clean the floors to firelight – that’s a job better left for the cold light of day. Similarly, it’s not as easy to check for mud on your boots in firelight. I wouldn’t be surprised if people we more inclined to leave them at the front door if they came home after dark.
Low output lights seems to create less extraneous stimulus by creating more focus on areas nearer the light source.
Ow! My Eyes!
In addition to the lower intensity of firelight, it also gives has a much warmer colour temperature. At the opposite end of the spectrum is the light you’re confronted with when visiting a convenience store lit by fluorescent tubes.
Color Temperature is measured in Kelvin and strangely enough a lower value refers to a warmer light. It refers to the temperature of a black body radiator that emits a light of comparable hue. The ‘cold light of day’ is up there with fluorescent tubes which might explain why walking into one at night can be feel so unpleasant. Suddenly adjusting to a different color temperature seems to be a bit jarring for some people.
|1,700 K||Match flame|
|1,850 K||Candle flame, sunset/sunrise|
|2,700–3,300 K||Incandescent lamps|
|3,000 K||Soft White compact fluorescent lamps|
|3,200 K||Studio lamps, photofloods, etc.|
|3,350 K||Studio “CP” light|
|4,100–4,150 K||Moonlight, xenon arc lamp|
|5,000 K||Horizon daylight|
|5,000 K||tubular fluorescent lamps or Cool White/Daylight compact fluorescent lamps (CFL)|
|5,500–6,000 K||Vertical daylight, electronic flash|
|6,500 K||Daylight, overcast|
|6,500–9,300 K||LCD or CRT screen|
|15,000–27,000 K||Clear blue northern sky|
Walking the dogs at sunset led to a surprising discovery. On returning home I needed to enter the house in the dark to light my lamps. (I’m pretty sure people used to keep a hand lamp on the hall stand to make this task easier/safer!). On returning home one evening I discovered I could navigate reasonably well using just the light entering my windows from the night sky and street lighting.
“Rhodopsin is the chemical that allows night-vision, and is extremely sensitive to light. Exposed to a spectrum of light, the pigment immediately bleaches, and it takes about 30 minutes to regenerate fully, but most of the adaptation occurs within the first five or ten minutes in the dark.” Wikipedia
“The human eye can function from very dark to very bright levels of light; its sensing capabilities reach across nine orders of magnitude. This means that the brightest and the darkest light signal that the eye can sense are a factor of roughly 1,000,000,000 apart. However, in any given moment of time, the eye can only sense a contrast ratio of one thousand. What enables the wider reach is that the eye adapts its definition of what is black. The light level that is interpreted as “black” can be shifted across six orders of magnitude—a factor of one million.”
- Wikipedia entry to Adaptation (eye) – Note that it does not contain a citation!
Firelight doesn’t seem to blow away my night vision. When I walk out into the backyard I can see pretty well.
How Low (Light) Can You Go
The idea that my eyes had a contrast ratio of 1000 but that I could potentially sense across nine orders of magnitude led me to try to create a darkroom in my house. In short I failed to stop all light from entering my living room. At first it appears that the bin liners taped to the windows had worked but as my adaptation progressed I could see lighter patches on the windows where the bin liners were not doubled over. Reflected light from the ski was seeping through!
That said, the light getting in was not enough to allow me to see my hand in front of my face – the quintessential measure of darkness. My hand was visible if a held a lit cigarette close to it but not when I moved it a foot away. I was amazed at how sensitive my eyes were to light in such a low light environment. How much light does a lit cigarette emit? I would love to know if that’s been measured!
Looking around the room I could see what looked like light seeping under the door. This light originated from the street, passed through the window in my front door and then down a long hallway. It occurred to me that in this modern era it’s almost impossible to keep light out.
To Be Continued?
The Urge to Own
Something about my personality has seen me always running my own servers. In the late 90s I setup a Pentium 100 with a permanent 28.8 kbps modem connection to the Internet in a wardrobe at my parents house. It hosted my mail and web services for a few years (including 18 months spent living in the U.K.). Something about knowing the system down to the metal, and beyond that even, to the environment has always been important to me. I think amongst systems people I’m not alone.
vs. Allure of The Cloud
Various factors have led me to abandon (at least for now) my desire to host@home:
- power consumption (waste & cost) & heat output
- single points of failure (power, ADSL, theft)
- desire to eat my own dogfood
A few years back I found other services to be cheaper than Amazon’s AWS offerings. I’m currently exploring what has changed since then and how individuals can use Amazon AWS to provide performant, highly available Internet services at low cost.
Mobile is Changing Everything
There are some great tools out there for controlling your Amazon services from mobile devices. Cloud Services Manager is a great app for iOS that enables control of AWS services on the go. My SSH client of choice for connecting from iOS is Prompt by Panic, Inc. These two alone let give you a lot of control from your iPhone (or iPad).
Cost Savings in Dev Land
When EC2 was first launched you lost everything if you shut an instance down. These days Elastic Block Store (EBS) volumes are the default which means you can stop and restart instances as you need them, paying only for the hours they’re running. This can make it more comfortable to tinker knowing you’re only paying while you’re using it. Running 10 x m1.small instances will cost $0.80 an hour which is quite affordable.
Note that you’re charged by the month for the EBS volume the instance uses. The charge includes a charge of approx. $0.10 per GB-month of provisioned storage and $0.10 per 1 million I/O requests. I believe that creating a 10 GB EBS volume and destroying it an hour later would be counted as 10 GB-months but I want to confirm (or refute) this.
To Be Continued…
Today I did the the Toyota Altona plant tour.
The tour was exciting and enjoyable. My favourite moment was when our guide pushed away a pinboard to reveal a line of eight cars being operated on by large welding robots. Sparks were flying in what must have been dangerous work when humans did it.
I think it will take a couple of nights to decompress and digest the information - there was a lot to take in - but here are some initial observations:
- Assembly line workers perform a very different profile of work to knowledge workers. Wherever possible they seem to have been replaced with machines.
- Humans are required on the line for processes where increased levels of dexterity, mobility, visual perception or tactile ability are required.
- The robots and humans seem to get along well. When humans stop for morning tea the unmanned vehicles that carry parts around go and charge themselves.
- Quality Circles - staff can form a quality circle if they believe there is an improvement that can be made to process. There is a well defined structure to the process which helps staff participate in modifying the process.
- The system is incredibly well run but we saw very few “screens”. Reports and graphs were printed and pinned on boards. Dynamic status boards were painted with coloured lights to indicate status. A large board would have a similar level of visual detail to an iPhone app. Simplicity!
- The work environment was sympathetic to the humans in it. Noise wasn’t excessive and they used music to signal problems on a line.
- If staff climb into a machine they put a lock with their name and photo on it - a great safeguard that makes workers responsible for their own safety.
Amazon are reporting degraded performance for some volumes in a single AZ in the us-east-1 region.
Twitter has lit up with complaints. An amusing one referred to “Amazons Elastic SLA“. Overheard in the office “The Cloud’s down! Does that mean it’s sunny?”
Fire Drill for the Cloud or You’re Doing it Wrong
Some pretty high profile websites are timing out which seems to indicate we’re not the only ones to have failed to take advantage of the high availability made possible by the AWS service stack.
More concerning though is the lack of design effort put into their error pages.
Take a Lesson from the Masters
My all time favourite 404 page captures the awkward embarrassment on an unsatisfiable request.
Killer app for iPads
Trying to justify getting yourself a new iPad3? My favourite use for my iPad lately has been watching quality screencasts by Gary Bernhardt (Destroy All Software) and Ryan Bates (RailsCasts). Each offer a premium subscription model where you pay $9 a month for access to their full catalog along with all new videos.
I’ve never really been into Screencasts but I’ve only recently discovered the secret seems to be in keeping them short. Here are two I’ve been really getting into.
Worth Paying For
How much do you earn each month from your craft? I wouldn’t think twice about paying $9 a month to the individuals who create such valuable art. To be honest I think we’re getting it cheap.
Destroy All Software
Gary Bernhardt has a communication style I can only describe it as “performance vim”. You spend most of the ten or so minutes watching him make text dance in a full screen terminal. It’s like pairing with someone you can really learn something from. The iPad is just the right size to make it work.
Ryan Bates has been producing short (5-12 minute) screencasts covering all manner of topics of interest to “Ruby People” for years now and making them available for free. Ryan makes his screencasts available via RSS which means they automatically find their way to my iPad.
Too many in our community give of themselves without making it easy enough for us to give back. I contacted Ryan a while back to ask how I could donate. I’m glad he has now made restructured things to make his ongoing work sustainable.
This morning I woke up with two images in my mind illustrating why we automate system tasks.
Two years after replacing my Apple Macbook Pro laptop with a Dell running Ubuntu Linux I’m going back to Apple. I moved away from Apple for a mixture of philosophical and practical reasons. One of the main reasons was my belief in the importance of a viable linux desktop operating system. The backflip came about because I feel happier when using Apple products. In my attempts to get away from Apple I think I’ve learned more about why they have been so successful.
Android was the Catalyst
I didn’t get a smartphone until mid 2011 and even then it was mainly because the battery on my Nokia was needing to be charged nightly. I picked up an HTC Sensation and began hating it almost immediately. I’m usually pretty good at pointing out flaws but the HTC was a bit of a mystery to me. While I can list a few flaws (battery not lasting a day is one!) I just didn’t like using it. After three months I decided to buy my first iPhone.
I Feel Love
So this is the fucked up thing. Within 30 minutes I was texting people to tell them how much I love my new iPhone. It may make me sound like a total fanboy but even while I was in the store I was bonding with the device. It feels wrong saying I love a machine but at the same time I’m curious how it could elicit such emotions. I can only put it down to the design of both hardware and software.
The Cathedral and The Bazaar
Steve Jobs was the high priest at Apple. We’re told he was obsessive about detail and that it was his way or the highway. Part of the reason I avoided getting an iPhone was the control exerted over the distribution of Apps through the App Store. I was surprised and disappointed by my first experience of the Android Marketplace. A search for “shopping list” returned hundreds of apps with no indication which were most downloaded or highly rated. Maybe you can’t design an OS or phone by committee?
Get Out of my Way
If I’m going to be iPhone boy then life would be easier if I used OSX on my desktop.
It’s been about 4 years since I last bought a new Macbook Pro. My efforts to avoid vendor lockin are now being replaced by efforts to avoid unproductive work (like debugging problems printing from Ubuntu 11.10). I want to get on with the fun stuff and OSX just seems to make the fun stuff so much easier.
So What Now for Freedom?
I was shocked earlier this year to hear a techie say he wouldn’t care if the linux desktop went away because he’s happy with OSX. My issue is that Apple could make OSX unpleasant at some point in the future and without a viable alternative to switch to we would just have to accept it.
I don’t think me going back to Apple is going to make an ounce of difference to Linux but what would the world be like if everyone followed this path? I guess I’m no longer willing to sacrifice my own happiness trying to support this particular ideal.
Well Done Steve (and Company)
The iPhone and Macbook Pro are masterpieces. (I didn’t mention I’ve had an iPad for the past 12 months and love it to bits). I tried to extract myself from this web of awesome production but have failed because they are so well designed. I would love to create something as compelling.