Sure! They are called particle accelerators.
(Of course, what they do is provide information on the structure of
the sub-atomic particles, a sort of 'seeing', but not quite direct
ordinary seeing.)
Subatomic particles are so small they always have to be treated
quantum-mechanically, which means that they occupy states that may
extend over larger amounts of space than their natural radius, just as
electrons occupy cloudlike orbital states around the centers of atoms.
Protons occupy similar cloudlike states inside of atomic nuclei, and so
do neutrons. Protons themselves are made up of smaller pieces, called
quarks and gluons. The proton itself is the collection of cloudlike
states of the constituent parts.
The reason we know all of this is that we've been able to fire
projectiles very fast at these objects. Light works great in an
ordinary microscope, but the wavelength of visible light limits our
ability to see small stuff. To 'see' small stuff, you need light with
short wavelengths. Pretty soon you need x-rays and higher-energy
photons (with shorter wavelengths). But x-rays are hard to focus and
hard to measure precisely from where they come. So instead a favorite
projectile is the electron. Electron microscopes work by throwing
energetic electrons at a target specimen and looking at how they bounce
off. The higher the energy of the electrons, the shorter their
quantum-mechanical wavelength, and the smaller the features can be
resolved. Electron microscopes are very useful, but cannot see inside
the nucleus of atoms unless the energy is very very high.
At the Stanford Linear Accelerator Center is a 2-mile-long
electron accelerator, with a peak energy of 45 billion electron volts
per electron it accelerates. These can be trained on a target of
protons or neutrons and the scattered electrons detected in elaborate
experimental apparatus. It is experiments done there in the 1960's
which proved the existence of quarks inside the proton, acting just
like an electron microscope on a big scale.
Even bigger particle accelerators have been built, and they have
been used to produce new, exciting particles no one dreamed existed.
Now we have a good model which explains what we see, but it has been an
exciting ride, and there are promises to find more stuff as we look at
higher energy scales, which corresponds to smaller and smaller distance
scales.
Tom
(published on 10/22/2007)
