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Asked by jabby to Arttu, Ceri, James_M, Monica, Philip on 17 Jun 2011.
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Philip Dolan answered on 17 Jun 2011:
That’s quite an interesting question. At the moment, the general consensus amongst physicists is that the laws of physics have little to no meaning at scales any smaller than 1.6×10^(-35)m. This can also be written as 0.00 … 30 more 0’s … 0016m. To put that in perspective, if you were to make this length (the Plank length) about a metre, an atomic nucleus would have to be scaled up to the size of the galaxy we’re in. More or less. So it’s pretty small.
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Ceri Brenner answered on 17 Jun 2011:
hi,
When you think of the smallest things that exist, you have to think of what atoms are made of.
The whole idea of sub-atomic particles having a ‘size’ becomes a bit fluffy when you get down to the level of fundamental particles like electrons or quarks. It’s better to describe them as wavefuntions and packets of energy, rather than objects. However, a ‘classical’ description of the size of an electron is approx 10^(-15), and the classical description of a quark makes them even smaller than electrons, and at these kind of radii, we are approaching the limit of what we can directly measure in experiments, so they could be smaller but we can’t measure them. -
Arttu Rajantie answered on 17 Jun 2011:
Our current theory of particle physics (which is called the standard model) describes elementary particles (leptons, quarks, photons, gluons, and W, Z and Higgs) as pointlike objects, so in that sense they have zero size and would be the smallest things in the universe. However, it is likely that the theory is not valid at very short distances, so they may well have a size. And ultimately we know that theory has to fail when we approach the Planck scale as Philip writes.
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