Did you get it right? Let me know in the comments.

I've recreated the effect below. To make it work, close your eyes for 10 seconds. When you open them, immediately look at the grey dot. The dark region in the middle should appear to expand for about a second:

I'm not sure if this has been done before or even if it works for anyone but me! Let me know if it works for you.

My theory is that when you first open your eyes, your pupils are dilated, so a lot of light is coming in. As a result, the dark patch looks less dark. In the fractions of a second after you open your eyes, your pupils contract. Less light gets in, so the dark patch gets darker. Because there is a gradient from the middle outwards, that darkening could also be interpreted by your brain as the dark patch expanding.

It might be that other things are happening besides your pupils contracting. Your brain does all sorts of adjustments to the information coming from your eyes.

Film camera operators talk about white balancing before taking a shot. It's where they make adjustments to their camera so that things that are supposed to look white actually do end up looking white. Your brain does some pretty intense white balancing too and it leads to a phenomena known as colour constancy. There's also brightness constancy going on in your brain. And if this brightness constancy takes any sort of time to kick in, that could also be an explanation for the effect in this illusion.

The chain is the stuff from vertical blinds. The thing you pull on to open and close them. Searching for metal 4.5mm bead chain on ebay gets you the right sort of thing. That also bring up the linkages you'll need to buy to make the chain really long.

The reason it self siphons is that the chain pulling down outside the beaker is longer (and heavier) than the chain pulling down on the inside of the beaker.

The reason the chain loops up higher than the rim of the beaker is a bit of a mystery. I think it's to do with the fact that the beads are changing direction and it can't do that instantaneously as that would represent infinite acceleration. So a big loop is formed. I don't know, something like that.

You can also follow Matt on twitter. And catch us both live in Festival Of The Spoken Nerd.

Here's my earlier post about Benford's Law.

Your left hand and right hand are mirror images of each other. There's no way you can position your left hand so that it looks like a right hand. It will only look like a right hand if you look at it in a mirror.

There are molecules like this in chemistry. Molecules that can't be positioned in such a way as to look exactly like their own mirror image. These are called chiral molecules. We talk about them having a handedness because they share this property with our hands.

But what about rubber gloves? You might think that a left handed rubber glove can't be positioned in such a way as to look like a right handed glove. But turning a glove inside out does exactly that!

That's why in chemistry, a chiral molecule that can be manipulated into it's own mirror image, is called a Euclidean rubber glove.

So what about socks? When you first buy a pair of socks, left and right look exactly the same. They don't have this chiral property. But after you've worn them a while and put a hole in with your big toe, they do.

So if you've got a big toe hole in your sock, you can make it more comfortable by turning it inside out. The hole will switch to the other side where your toes are less likely to poke out.

This can make pictures look funny, so manufacturers add a filter to block the infrared and give you a more natural image. Actually the filters don't do a perfect job and if you fire a TV remote control at your camera phone you should see it light up on the screen.

All this means you can have a bit of fun with your old web cam. You can remove the infrared filter then add a visible light filter so your webcam only sees infrared!

There are loads of different makes of webcam but most of them have a bit that looks like this:

It's the lens assembly. The end you can see is the end that sticks out of the webcam. At the other end is the IR filter.

I was able to slice off about 1mm from the end to release the filter using a stanley knife:

Then it just screws back into place.

So now you're letting in the infrared all you have to do is block out the visible. You can buy a special filter for the job, or (thanks to Alby Reid) you can cross two polarising filters because these generally only block out visible light. Try the lenses from a pair of 3D glasses (with ReadD branded glasses you'll need to flip them around in all different combination until you find the one that blocks light. That's because they filter circularly polarised light and are a little more complicated than straight polarisers) Here's my setup:

For a while I wasn't seeing anything, just a black screen. Then I realised all the light in room was from energy saving lightbulbs which give off no infrared. I switched to an old style incandescent bulb and the room lit up!

Here are some weird looking things (click to enlarge):

I think my Mona Lisa might be a fake!

Only the Queen is left when you take away visible light:

And here's my eyeball:

Plants aren't that into infrared:

http://feeds.feedburner.com/RedditFeedWithAScoreThreshold

1000 won't work for everyone so you can customise the feed from the Yahoo Pipe I built:

http://pipes.yahoo.com/pipes/pipe.info?_id=4a3af06dcba612424a858ea79dd263db

You can also specify the subreddit.

"Features"

It feels a little grand to be calling these features but here we go:

• Links to images have the images embedded into the feed.
• If the link is to an imgur.com html page it embeds the image from that too.
• Links to youtube are embedded.
• The feed has a link to the comments page, the posters page and the subreddit page.

Limitations

The Yahoo Pipe gets its data from the top stories of the day. On the "all" subreddit for example top stories of the day rarely get above 2500. That's not to say stories don't eventually get above that, it's just you have to look at top stores for the week or month etc to see scores that high.

As this pipe only scrapes the top stories for the day you'll start to miss out on stories if you put a value over about 2000. The same goes for subreddits but with a different threshold.

If you'd like a higher threshold option let me know and I'll look into making pipes that get their data from the top week and month stories.

If you subscribe with google reader this becomes relevent:

http://www.google.com/support/reader/bin/answer.py?hl=en&answer=97875

Basically google reader has an algorithm for working out how often to refresh a feed. If the feed is relatively new to the world that interval will be large but will get smaller. And you can manually refresh if you want to.