How small is the universe?

What follows is my summary of the BBC Horizon show "How small is the universe?" as shown on SBS television in Australia on Monday January 13, 2014.

One of the reasons scientists are interested in the very small are that things don't just get smaller, they change, for example, gold nanoparticles are used for the red in stained glass windows. 

The PICO electron microscope in Germany was the first to have a resolution of up to 50 picometres allowing individual atoms in a gold nanoparticle to be seen. But although the atoms appear to be solid spheres, they are mostly empty space, with a cloud of electrons swarming around a tiny nucleus. 

In the ATLAS experiment at the Large Hadron Collider, they are looking inside that nucleus by smashing protons together at high energies to see what "bits" (quarks) they are made of. The LHC was responsible for the discovery of the Higgs boson which seems to complete the Standard Model of particle physics. 

But physicists aren't stopping there, they want to know what these fundamental particles are made of. Also in Germany, physics professor Jeroen van den Brink is splitting electrons into spinions, orbitons and holons. 

And if Andy Parker is able to create miniature black holes at the LHC, he will have demonstrated the existence of at least one extra dimension into which gravity is "leaking" making it appear weaker than the other forces in the three-dimensional world we appear to live in. 

Of course, if string theory is correct there are actually eleven dimensions and this universe is simply one of many multiverses each with its own laws of physics. But strings would be far too small to see, approaching the Planck length. And to see things that small, we can use the whole universe. 

In an experiment using the MAGIC telescope, photons from distant gamma ray bursts have been observed to arrive at slightly different times depending on their wavelength suggesting that space-time is not uniform at the Planck scale. 

And so the physics of the 21st century and beyond may have to deal with particles beyond the Standard Model, extra dimensions, multiple universe and a "lumpy" space-time (or quantum foam) which means the speed of light is not constant.