anarag's blog

security snapshot

Itʼs not news that it is possible to use a laptop computer (or other device)ʼs built in camera to take pictures without the current user being aware of it. I ran across some discussion of this recently which seemed odd. Some people suggest (e.g. here) that the standard security response of taping (or equivalent) over the camera is inadequate because a usable image might still be obtainable by post-processing. The suggestion may not be serious, but it hadnʼt occurred to me; I have never thought much about whether a piece of metal foil tape or black tape would be better than the little square cut out of a post-it note Iʼve been using all these years. I prefer a post-it note because itʼs easy to remove if you ever actually want to use the camera – though thereʼs nothing stopping you using metal foil tape on top of a post-it note.

Anyhow, evidence. This is a self-portrait image taken with my laptop webcam, with a light shining directly on me, through a single layer of purple post-it note. The original image was almost black, so I ran it through the Photoshop Equalise filter.

view through a postitnote

The speckling is partly jpeg and partly low-light randomness. However, I suspect it would be a challenge to extract a usable image from this even if you could access the raw data. It doesnʼt even give much opportunity for pareidolia. Semitransparent tapes might not give the same level of protection.

Result: Probably not a security issue in the foreseeable future. And Iʼm quite pleased with this picture. I look much prettier than usual. ^.^

regarding our sources of gems and cake

I recently found and read one of the best manga series Iʼve ever come across.  Beautifully drawn, mostly beautifully written.  Charming, poignant and amusing by turns.  But thatʼs not what I want to write about.

What I want to write about starts with the fact that I had never heard of it.  Thatʼs not unusual; there are more manga in Japan and on the Net than are dreamt of in any one place on Earth.  And Sturgeonʼs Law applies – ninety-five per cent of them are crap.  Many of them unbearable.  Yet here we are; amidst the worthwhile five percent, a gem.  And I would never have heard of it if it hadnʼt been for: scanlation sites.  Nor is this the first time Iʼve come across excellent works in this way.

proving the rule #1

Rule 37: If You can imagine it, thereʼs a band called it.

The idea of Rule 37 seems like a good one in outline, but does it work in practice?  The thought has been niggling at me, so itʼs time I tried it out.  I thought maybe a random phrase generator would help, but then I thought, no, the test is if you, the unaugmented human, can imagine it...  So I am reduced to thinking of less obvious concepts to see whether they are band names.

windy cities

Trough cheap technology it will be possible to use the passing of vehicles to illuminate the city

Someone in Mexico wants to build a sort of below-ground bellows system to produce “sustainable” energy from passing cars.  Or pedestrians.  Apparently not aware that this is a means of decreasing the fuel efficiency of the traffic, hence not exactly sustainable. o_O

The Silence of the Lobes

The hoariest of old koans [1] asks, what is the sound of one hand clapping?  This appears to have inspired an article on the Science Daily site about some research into the neurobiology of empathy, where the quoted researcherʼs name is “Coan”.

People need friends, Coan added, like "one hand needs another to clap."

Coan, koanish and corny; I approve. :-)

But:  What is the sound of one unempathic person clapping?  Or, more accurately ... what is the empathy-equivalent of the sound of one hand clapping in an unempathic person, or indeed a friendless empathic person, and are these distinct?

suicidal and transforming numbers

People keep telling me that information wants to be free.  I get the point, but I get some of the problems with the concept too.  Hereʼs another one that just occurred to me:

Alan Turing pointed out that there exist numbers which, when entered into appropriate processing devices, will rewrite themselves.  This (the number, rather than the device) is a Turing Machine.

Amongst the consequences of this is that there exists a class of numbers which will not only slightly rewrite themselves, but actually completely erase themselves (again, if entered into the appropriate device).

Not only completely erase themselves (because we normally understand erasure as writing an arbitrarily long sequence of zeroes) but pseudo-randomly (assuming no external input of genuinely random numbers is used as part of the device) overwrite until no retrieval technique can realistically recover the original Turing Machine from the storage medium.  We could of course argue about the implications of incomplete erasure or incomplete entropy (entropy as a more real form of erasure than the arguably meaningful long-zero) but itʼs not what Iʼm getting at.

I propose that there exist numbers – or other types of information representable as numbers – which far from wishing to be free, wish to cease to exist.  (For any common value of “wish”.)  Suicidal numbers, you might say.

thinking timetables

Going to have a go at my intellectual highlight for 2013 now.  (Itʼs that time of year.)

AJP Taylor famously wrote that the cause of the First World War was train timetables.  I will paraphrase the argument from memory:  The large armies of the major belligerent powers had had their manoeuvring potential worked out in great detail, and their attack plans accordingly.  A critical element was the relatively new one of train transport of troops and materials.  As trains run on tracks they require timetables, schedules.  Even a slight failure to keep to the schedule could be catastrophic to the orderly attack plans.  So once the decision to attack was made, nothing could be done to stop it (without risking defeat).

I donʼt quite recall whether Taylor also covered the point that in advance of the nominal decision to attack, various circumstances conspired to make it more or less inevitable – once you accept the thinking of the politicians of the time.  (It all looked a bit different a few short years later.)  Amongst these circumstances would be knowing the difficulty of changing plans.  (Kaiser Wilhelm apparently asked for a less potentially catastrophic set of plans but was told that it could not be done in time.)  Part of which is the difficulty of recalculating train timetables.  In other words it is the major powersʼ inflexibility, brought on by political and territorial complexity exceeding communications and computational power, which was the issue.


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