Tag: answer

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Old

Things 57: Webcam-split-screen, Freaks and Potatoes

(Originally sent September 2009)

Forthcoming film
“Surrogates” is due to be released in the UK on the 25th of September. An adaptation of a graphic novel, it looks to be a solid Sci-Fi in what I consider to be the technically correct sense: positing a potential technological development, the story investigates what might happen in a society where such a thing is possible.

In this case the development is ‘surrogates’ – robot avatars that people control remotely, an idea just nicely at the edge of conceivable possibility.

I think the trailer gives too much away, so if you want to see the basic premise just watch the first 60 seconds, and I strongly recommend not watching beyond 1 minute and 30 seconds (seriously!) if you can possibly resist it!

Video
I saw a video pair on YouTubeDoubler (here – pause the left video until the right one tells you to start it) in which two people use two webcams together to create a video for a duet, and I thought “Good, but could do better”. Someone did:

(Starts to get clever at 40”, goes nuts at around 3’10”)

Quote
Webcomic ‘Pictures for Sad Children’ suggests an improvement (site was taken down in 2014 – T.M. 17/5/22) on the ever-unsubstantiated ‘never more than 3 meters from a rat’ saying:

“We’re in earshot of two terrible things at all times”

Link
“Freaks survive because they are strange” – a great headline, a slightly silly experiment involving food-bearing model salamanders, and a plausible-sounding partial answer to the ‘maintenance of variation’ problem with evolution.

Potato Puzzle
You have 100 kilograms of potatoes that are 99% water by weight. You store them in a cupboard, and when you test them again a week later you discover they are now 98% water by weight. How much do the potatoes weigh?

Magical Ground Squirrel Puzzle Answer:
If the magical ground squirrel is able to position the bridges (say) East-West with such accuracy that an imp wanting to go North could not work out which one pointed slightly more Northerly and so had to choose randomly, then the squirrel has good odds of working out the result of the election by doing exactly that and leaving the bridges there the entire time.

If the imps are headed to the good training centres in the East and West, there will be no random choice made by them and when they have all come out 500 will have gone East and 500 West.

However, if the imps want to go to the evil training centres in the North and West, they will be choosing a bridge randomly. In that case, there is (by my calculation) only about a 2.5% chance that exactly 500 will choose each bridge. There’s a 97.5% chance more will go one way than the other, and in this case you could be sure they were evil.

Categories
Old

Things 56: Robot Hand, Earth and Moon, Magical Ground Squirrel Puzzle

(Originally sent August 2009)

Quote

“Most problems are side effects of solutions to other problems.” – Eskil Steenberg

Video
Once you have built a machine or robot that can do something, the really cool part is you can then see how fast it can do that thing. In the case of this astoundingly dextrous robot hand, the answer is: alarmingly fast.

Picture
A simple idea – a picture representing the earth, the moon, and the distance between them, in the correct proportion.

(Click for description and links to bigger versions):

Last Week’s puzzle
Why are ~10% of people left-handed?

Implicitly, the question is really why 10% instead of 50% or 100%, either of which would be intuitively more obvious (although you’d still wonder why it was one out of those two).

A frequently given answer is that in combat there is an advantage to having a handedness that most others don’t have, since you will be practiced at fighting opposite-handers whereas most of the competition will be practiced against fighting same-handers. An increased number of left-handed players succeeding in adversarial sports such as tennis is cited as evidence.

What’s fascinating about this argument is that it manages to sound convincing but it cannot possibly be the whole answer. If there was an advantage to being in the minority, and if that trait is genetic, then we would expect that over evolutionary time-scales a 50/50 split would emerge. (If fewer are left-handed and have a survival advantage by this argument, then more of the next generation will be left-handed, and so on until no advantage remains).

For the theory to work, there would need to be an evolutionary pressure that goes the opposite way, making left-handedness disadvantageous in some way, with the net effect of the two pressures to be a 10% incidence rate.

As it turns out, it seems we don’t have a definitive answer, but surveying the various theories and research presented in this wikipedia article below it seems to be connected to asymmetry in brain development (a deeper question in itself), with cultural effects (such as fighting) giving an additional skew in the short term.

This Week’s puzzle
There’s a very nice puzzle in quantum information theory. This is my attempt to set the same puzzle in less specialist terminology, and although it ends up being quite long, it does involve a magical ground squirrel.

There is an island in the centre of a large lake.

On the island is the entrance to a tunnel that goes deep underground to the imp underground city.

To the North and South of the lake are two evil imp warrior training centres.

To the East and West of the lake are two good imp warrior training centres.

There has recently been an imp general election, and they will either have elected a good leader or an evil one. 1,000 imp warriors will now be allocated a training centre, with exactly 500 allocated to each one. So, if an evil leader has been elected, 500 imp warriors will be assigned to the North training centre, and 500 the South training centre. If a good leader has been elected, 500 imp warriors will be assigned to the West training centre, and 500 to the East training centre.

You are a magical ground squirrel that lives on the island.

A pair of bridges connect the island to the lake shore in opposite directions.

Your magical power is exactly this: you can rotate the pair of bridges so they lie in any direction from the island, so long as they remain directly opposite one another. So you could choose to have one bridge head directly North and one directly South, or one directly North-West and the other directly South-East, and so on. However, you must never use your magic when an imp is on the island or a bridge, as they will notice and put you in their magical animal zoo.

The 1,000 imp warriors are about to be sent out, one each hour, to go to their respective training centres. Imps are highly random creatures, and they also have a pretty amazing sense of direction. They will be coming out in a random order, and they will head along the bridge that most closely matches the direction of their training centre. If the bridges seem to be perpendicular to the direction they want to go (for example, if the bridges lie East and West and the imp wants to go North) then the imp will pick a bridge at random.

Using only your magical ground squirrel powers, what is the best way to work out whether the imps have elected a good or evil leader?

(Note: this is not intended as a lateral thinking puzzle! You just have to decide how to rotate the bridges and interpret the resulting imp behaviour. But I suppose you could try solving it laterally as well. P.S. Imps can cross a bridge in under half an hour).

Categories
Old

Things 55: Cancer, Pentatonics, Handedness and the Police

(Originally sent July 2009)

Films
I saw Moon, which was a very nice bit of old-school sci-fi with a few nice ‘ah-ha!’ moments.

I saw G-Force 3D, and was amazed at how special effects clearly follow some kind of Moore’s law, while good writing remains a nearly insurmountable challenge.

Link
There’s a few sites out there attempting to keep up with what’s referred to as the Daily Mail’s “ongoing effort to classify every inanimate object into those that cause cancer and those that prevent it.” I like the way this one is helpfully laid out.

Of course, what would be nicer would be to use the research papers as a basis for such a project rather than the Daily Mail, at which point you’d probably need better risk-assessment functionality.

For example, I read a proposal to break global warming down to an individual scale – so if collective human actions increase the average temperature by 0.5 degrees over several decades, we could create an approximation for the temperature increase due to the production of any given product or action, and even though it would be tiny it would come to have meaning – e.g. this laptop causes a 23 picokelvin rise, but this one caused 573.

In practice, we’ve seen Carbon labelling, which is I suppose somewhat more accurate and tangible.

Unfortunately risk factors are really too complicated to be distilled to a single number for a single food item.

Video
Bobby McFerrin with a nice demonstration about how intuitive the Pentatonic scale is:

Last week’s puzzle
Why is gravity 37% that of Earth’s on Mars, even though Mars only has 11% of the Earth’s mass? Clearly there are Laws Of Physics at work, and we can’t fairly expect to have an intuitive understanding of how strong gravity ‘ought’ to be on planetary scales.

That said, there are two factors clearly at work:

– Density: Mars is slightly less dense than the earth – 3.9g/cm^3 vs 5.5 g/cm^3, or 71%

– Radius: Mars’ radius is 53% that of Earth’s. If you were somehow standing on a platform one earth radius away from the centre of Mars, the gravity you feel would certainly be weaker than the 37% that you would experience on the surface.

(Side note: if earth (or indeed any planet) were hollow, there would be no gravity on the inside, as the gravitational pull due to the outer shell cancels out no matter where you are in the interior!)


This week’s puzzle
Why are about 10% of people left-handed?


Quote
The Week is a weekly summary of “everything you need to know about everything that matters”, expertly editing together coverage of the main stories of the week into coherent, balanced, and concise summaries.

Here’s a cut down version of their concise version of a story from Germany, which as well as cutting all the fluff from a story that could probably be expanded to a movie adaptation I also liked because it’s a wonderful case of reversing the usual fiction trope that ‘Police are Useless’

“Germany’s wealthiest woman, Susanne Klatten hit the headlines last year when her former lover was arrested for trying to extort €49m from her. He told Klatten that he had made a secret video of them having sex and threatened to make it public unless his demands were met. But Klatten went to the police and he was arrested.

“Last month, three men wrote a letter to Klatten in which they claimed to have a copy of the sex video and demanded €800,000 and a BMW car for its return. Once again Klatten called the police and the three were arrested.”

Okay, it probably wouldn’t make a very good movie.

Categories
New

Things 102: Bionic Cat Ears, Brilliant Journalism, Drawable Monsters

This Week’s Puzzle
I have a Tumblr on which I post daily things to draw, called Now Draw This. I really want to make sure I credit the relevant artist when I post a piece of artwork. (I should do that with the photos too, but for various reasons that’s not as important to me).

TinEye is an awesome reverse image search engine, which in the past has helped me track down artwork even when the version I had turned out to have had the colour palette significantly edited. Pretty clever.

The problem is, this site posted the above image (of Ico and Yorda from the game Ico), and neither TinEye nor wily Googling is helping me track down the original artist.

Can you find out who created the above image originally?

Video
Technology expands the range of things we can do. As a society we try to keep up by generating some kind of idea of what we should do. For example, mobile phones enabled us to use ostentatious ringtones. For a while they were everywhere. Now, it seems we’ve collectively decided that’s not such a good idea.

So here’s something I hadn’t even considered: what if you could collect some kind of real-time usually-invisible data about yourself, and then manifest it with a clear physical signal? Would that ever be a good idea?

Link
Michael Lewis writes long articles on complex but important topics, that are nonetheless incredibly engaging, thus creating pretty much optimal long-form journalistic pieces. I highly recommend that you make time for his article Beware of Greeks Bearing Bonds (which I thought I’d linked to before but can’t find in my records), and if you like that then you should also read When Irish Eyes Are Crying.

Quote
Joe Cornish, director of Attack the Block, interviewed by Little White Lies:

If you look at a lot of the digital creatures in Harry Potter, you couldn’t go home and sketch them – you’d need a draughtsman’s degree. […] The charm is to go home and feel that it’s possible to figure out how they did it. When I was a kid, I’d go and see Ghostbusters and spend the next day trying to draw the Stay Puft Marshmallow Man, or trying to get the logo right. They had a graphic simplicity that was much more infectious and warm and authored than a lot of the stuff now.”

I had the same childhood experience, and I think it’s a really fun rubric. Attack the Block‘s creature design succeeded in exactly that way.

Last Week’s Puzzle
Last week I asked what the purpose was of this insect-eye mirror I saw on the ceiling in a bank in Vienna, but nobody hazarded a guess.

You can tell from the shadow that there’s a bright spotlight pointed at the mirror, so my hypothesis was that it was some kind of way to generate a bright, ambient light throughout the room. But it seems like overkill / overdesign if that’s the goal. And why would you want to have a diffuse, shadowless light that badly anyway? I like to imagine, completely baselessly, that there’s a local superstition about some kind of money-stealing creature that inhabits shadows. But if you can think of something more plausible, do let me know.