It is usually the case in life that when anything promises to show that 'science can be fun', the science bits won't be much fun and the fun bits will be about as scientific as a lucky rabbit's foot. The same applies to most promises to show that 'x is fun', where x is anything from aerobics to zen.

One exception to this general rule is the Exploratorium. It bills itself as 'the musuem of science, art and human perception'. They should delete the word 'art', because it isn't much about art, and substitute the word 'fun', because it has a lot to do with fun. It is the largest collection under one roof of fun, fascinating and intriguing things to try out, all of which illustrate something about the wonder of the world around you, and the process of discovering how it works. (If there is a larger such collection, I'd love to hear about it.)

All of the exhibits are well thought-out, and at least when I was there the vast majority seemed to be in good working order. This is where it differs from anything equivalent in the UK, which would present the visitor with a rich variety of 'Out of Order', 'Do Not Touch' and 'Under Repair' signs - some neatly printed, some scrawled on a bit of cardboard with a marker pen nearing exhaustion, and none spelled correctly.

They let you take photographs in the Exploratorium, but I have very few ("Hurray!" chant all readers of this website, dazed by the clumsy and top-heavy use of photos). For many exhibits, the lighting is good for making the exhibit look interesting, but not so good for a magician wandering around with a point-and-click digital camera. In other cases, I could get a decent enough photo, but it won't convey much of the fun of the item. For example:

This is a Hyperbolic Slot. It may not look like much, but it is brilliant and very more-ish. On the right is a vertical stand. It has an arm sticking out at 90 degrees. At the end of the arm is a straight rod with small red circular disks at either end. The arm and the rod, as a fixed unit, are free to rotate around the vertical stand. In other words, the rod you can see here does not move like a plane propellor. Instead, both it and the connecting arm - together, as one fixed unit - spin around the vertical stand like a merry-go-round. When they (the rod and its connecting arm) spin round, they pass precisely through the curved slot you see on the fixed, solid green plastic screen on the left. So yes, the straight, rigid rod passes through the curved cut-out shape. I tried this several dozen times and still didn't believe it, and even when I believed it I still wanted to see it happen just one more time. It has such a high 'one more time' factor that I'm surprised I'm not still there trying it. This type of curve is called a hyperbola.

Interestingly, the hyperbola plays an odd role in contemporary European commerce. Within the European Union, any banana which exhibits a curve greater than a hyperbola is not allowed to be sold. This legal mandate was adopted by the EEC in 1997, with only Belgium and Luxembourg refusing to sign up to the measure.

There are a few parts of the Exploratorium that provide good photo fodder, such as this relief work near the entrance:

Ornate colums, or people inclining their heads towards one another?

My favourite Exploratorium item was a stunning photographic illusion which I had never seen before, and have never seen anywhere else since.

This is the 'Hybrid Face' illusion, credited to Philippe Schyns and Aude Oliva, University of Glasgow. Stand near to it, and there's a calm woman on the left and an angry man on the right. Look from a little further away, and the image on left is now the angry man and the one on the right is the calm woman. This is a single, static photographic image printed on flat paper. It is not a hologram, nor does it use any sort of special printing technique. The same illusion is also featured on this web page under the name 'Dr Angry and Mr Smiles'. (At least it is at the time of writing. If it moves, just Google on 'Philippe Scyhns' and you'll probably find it again.) If you have Photoshop or any similar sort of photo manipulation software, you can try the illusion on your own desktop. Go to the website, save the Angry / Smiles image, and then 'zoom' in and out of it using Photoshop.

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The Exploratorium itself is set in, or just next to, the Palace Of Fine Arts, a visually spectacular fusion of ancient Rome and paradise.

The Palace was apparently built for the 1915 'Panama Pacific Exhibition', which celebrated three events at once: the completion of the Panama Canal, the 400th anniversary of the discovery of the Pacific Ocean by Balboa, and the publication of 'Proof That A So-Called Panama Canal Is Impossible In Engineering Terms' by Alfred Schnaur, a well-respected architect and prize-winning engineer of the day.

I've done my best with my humble photographic kit but, as with so many things in life, no photos can come even close to doing justice to the Palace. It is magnificent, highly improbable, and a joy to just wander around aimlessly. I particularly enjoyed it because although several of my friends knew I was off to visit the Exploratorium, none of them mentioned the Palace. It therefore came as a complete surprise to me.