Image © Tim Jones.
This beautiful image shows details of the ceiling of the Sagrada Familia basilica in Barcelona, illustrating architect Antoni Gaudí's love of mathematical design. © Tim Jones.
Image © Tim Jones.
A perfect number is a natural number whose divisors add up to the number itself. The number 6 is a perfect example: the divisors of 6 are 1, 2 and 3 (we exclude 6 itself, that is, we only consider proper divisors) and
1+2+3 = 6.
If a non-perfect number were an animal, it might look something like this.
If you play around with numbers for a while you will see why people have always been so fond of perfect numbers: they are very rare. The next one after 6 is 28, then it's 496, and for the fourth perfect number we have to go all the way up to 8128. Throughout antiquity, and until well into the middle ages, those four were the only perfect numbers that were known. Today we still only know of 48 of them, even though there are fast computers to help us find them. The largest so far, discovered in January 2013, has over 34 million digits.
Will we ever find another one? We can't be sure — mathematicians believe that there are infinitely many perfect numbers, so the supply will never run out, but nobody has been able to prove this. It's one of the great mysteries of mathematics. You can find out more in Number mysteries.
In the process of writing an article on curvature we got entirely distracted by making a geogebra worksheet showing the tangent, normal and osculating circle to any smooth function. The meaning and mathematics of all these terms is revealed in this article, but if you fancy getting your hands dirty yourself, have a play with the worksheet below. Please post your favourite function as a comment – the curvier and wigglier the better!
You can use this geogebra worksheet to see the tangent, normal and osculating circle of any smooth curve you choose - just change the equation f(x) in the left-hand panel.
Bat country. Image designed by Gwen Fisher, engineered by Paul Brown. © Gwen Fisher.
These lucky people are climbing around a 22 feet (6.7 metres) tall structure composed of 384 softball bats, 130 soft balls and a couple of thousand pounds of steel. The structure represents a Sierpinski tetrahedron: a fractal which has finite volume but infinite area. The image only shows an approximation of the fractal of course, as it would be impossible to make a full-on Sierpinski tetrahedon with its infinite intricacy, but it's beautiful anyway!
The picture, designed by Gwen Fisher and engineered by Paul Brown, is one of the images that appears in the book 50 visions of mathematics, which celebrates the 50th anniversary of the Institute of Mathematics and its Applications.
You can find out more about fractals here.
IMage courtesy of the Department of Civil and Environmental Engineering, Imperial College London.
This is one of friend of Plus Ahmer Wadee's favourites images from the book 50 visions of mathematics. It is of a demonstration at Imperial College in 1887 of the mathematical principles behind (or should that be underneath?) the Forth Bridge. The bridge was the largest spanning bridge in the world at the time and the technique behind it was an innovation, essentially balancing the forces involved using cantilevers. The men on the chairs (Sir John Fowler and Benjamin Baker) represent the piers of the bridge and the load on the bridge, in this case Kaichi Watanabe, one of the first Japanese engineers to study in the UK, is supported by the tension (in the men's arms and in the ropes to the anchors) and compression in the structure.
So, what holds up the Forth Bridge? Why, maths of course!
You can read more about the maths of engineering in Constructing our lives on Plus
If you love physics and making movies then this is for you. The Foundational Questions Institute (FQXi) is excited to present Show me the physics!, its first-ever video contest. Anyone can submit a video conveying the joys of physics to win a top prize of $10,000, and there are very attractive runner-up prizes too.
Whether you're a physicist or just a physics geek, and whether it's the geometry of space time (see top video on the right) or quantum immortality (see bottom video), all sorts of submissions are welcome. The aim is to enthuse non-physicists and provide a creative and visual space for the discussion and exchange of ideas. Examples of suitable topics are: