Saturday, 27 August 2016


There is a recipe in the back of Edward Lear's Book of Nonsense which begins like this:

"Procure some strips of beef,  and having cut them into the smallest possible slices, proceed to cut them still smaller, eight or perhaps nine times."

The recipe raises some interesting questions such as: What would these tiny pieces of beef look like? Is it even possible to slice anything past the molecular level? There is another question I am more interested in. If you slice things into small pieces, they take up less space. Could you eventually make things disappear entirely, just by slicing them?

As a matter of fact, it is fairly easy to break apart molecules; your body is doing it now. Atoms are more tricky, but scientists have split the atom more than seventy years ago. You rely on atoms fusing together in the Sun, after all. To answer our first question, the beef wouldn't look like beef past the molecular level. In fact, if you managed to split apart every single molecule in a slice of beef at once, it would trigger an explosion as the oxygen fuses to form the kind of air you breathe. (if you did the same thing to atoms, you would make a large nuclear explosion.)

Of course, it takes some pretty tremendous forces to split atoms. The only place where it is done on a big scale is in the core of a large star, when it dies. If a star is much bigger than our sun, it struggles constantly to stop collapsing in on itself.  The star relies on fusing atoms to survive. The moment a star runs out of fuel, its inner layers collapse. The outer layers of the star crash into the inner layers, and rebound into space in what is known as a supernova. What is left is the core. In a Sun-sized star, the core left is a white dwarf, which glows for a while before winking out. However, in a large supernova, the atoms are so strained by gravity they split apart and form an extremely dense and often quickly spinning object known as a neutron star.

Neutron stars are really strange things. They can be the size of cities but the mass of the Sun. They are mostly made of neutrons. Many have a fragile 'crust', which can fracture and create terrifying power surges. Some orbit a star, which they suck power from. Sometimes neutron stars merge and create massive bursts of light. Some neutron stars, known as pulsars, spin several times a second and emit energy from their magnetic poles.

Most weird aspects of neutron stars come from their incredibly small size and their amazingly large amount of mass. There is a type of object which has even more mass and a smaller size than a neutron star: a black hole. Black holes are made by splitting the components of atoms apart into individual quarks. Black holes are really weird. They are objects with a gravitational field so extreme, they can bend light. You cannot even see a black hole; you just see, well, a black hole. Around a black hole, time slows down and everything is redshifted. We barely know anything about black holes at all. All we know for sure is that they are unimaginably small and dense.

I wish there was a way to split quarks - the components of neutrons and protons - apart, but there isn't, as far as we know. And finally we arrive to the answer of our third question: It is not possible to cut a slice of beef into nothing, but you can make a black hole.

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