Ultrahigh-energy proton looks like a black disk

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The new findings provide the first experimental evidence that a proton becomes a black disk as its energy approaches asymptopia.

What does a proton look like? The common answer to this question is that protons are much too small (1.6 femtometers in diameter) to scatter light, and since light is necessary for us to see things, protons do not “look” like anything. But in a new study, physicists have gathered sufficient evidence to show that, at least at very high energies, the proton is a black disk

Even protons hold some mystery

A proton is made of two up quarks and one down quark. The three quarks are held together by the strong force, which is mediated by other particles called gluons. A lot of activity goes on inside a proton: quarks bounce around and exchange gluons, and virtual particle-antiparticle pairs constantly pop in and out of the vacuum. When accounting for these complex dynamics, and also that the wave-particle duality of quantum mechanics postulates that protons have properties of both waves and particles, visualizing a proton is not a simple matter.

To shed some light on this they accelerate protons to a speed near the speed of light and smash them.

Due to Lorentz contraction, the proton when its velocity approaches the speed of light should contract into a 2D black disk. At ultrahigh energies, the proton structure is totally dominated by the gluons instead of quarks. In contrast, at sub-asymptotic energies, the quarks play a more significant role and there aren’t enough gluon constituents to form a shape that is totally black or a complete 2D disk.

Relativity still rocks. I never thought about elastic and inelastic collision of protons

As the proton's energy approaches infinity, a proton will scatter any particle (for instance another proton) like a billiard ball half of the time (elastic collision) and totally absorb it the other half of the time (inelastic collision). Physicists have been investigating proton-proton collisions for several decades. By calculating the cross section of proton-proton inelastic scattering processes and comparing it to the proton-proton total (elastic plus inelastic) cross section, researchers have gained a better understanding of the inner structure of protons.

This experiment has also some more practical value:

The scientists' model even predicts the mass of the lightest particle state made from gluons, dubbed the glueball. This clue to the glueball's mass may aid in the search for glueballs, which has been a challenging goal of several experiments. In addition, the physicists' calculations predict that the black disk is expanding, which is in accordance with very general theoretic predictions from the 1960s.

This figure shows two protons crossing each other at the LHC at an impact parameter, b. Because of their velocity near the speed of light, the protons are contracted to thin disks. An analysis of the proton-proton cross section suggests that high-energy protons are black disks.

http://www.physorg.com/news/2011-12-...lack-disk.html

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Another awesome discovery. A picture of the shadow casted by a single atom has been captured! A single atom! Would you ever imagine such extreme optical imaging? Atom was held in free space by electrical forces.

Scientists trapped single atomic ions of the element ytterbium and exposed them to a specific frequency of light. Under this light the atom's shadow was cast onto a detector, and a digital camera was then able to capture the image.

They have reached the extreme limit of microscopy because it's impossible to see anything smaller than an atom using visible light.

"We wanted to investigate how few atoms are required to cast a shadow and we proved it takes just one," Professor Dave Kielpinski of Griffith University's Centre for Quantum Dynamics in Brisbane, Australia

http://phys.org/news/2012-07-photo-shadow-atom.html

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IBM scientists have been able to differentiate the chemical bonds in individual molecules for the first time using a technique known as non-contact atomic force microscopy (AFM).

It's a nanographene molecule. In that image we can "see" the individual bonds between carbon atoms AFM does miracles.

http://phys.org/news/2012-09-world-a...cal-bonds.html