A Photo Of Saturn. Took By Hubble With HSTWFPC2 On December 09, 2002 At 10:36:16. Detail Page On OPUS

Hyperboloid

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Where Does The Mass Of A Proton Come From?

“It is very accurately known how large the average gluon density is inside a proton. What is not known is exactly where the gluons are located inside the proton. We model the gluons as located around the three valance quarks. Then we control the amount of fluctuations represented in the model by setting how large the gluon clouds are, and how far apart they are from each other.”

If you divide the matter we know into progressively smaller and smaller components, you’d find that atomic nuclei, made of protons and neutrons, compose the overwhelming majority of the mass we understand. But if you look inside each nucleon, you find that its constituents – quarks and gluons – account for less than 0.2% of their total mass. The remaining 99.8% must come from the unique binding energy due to the strong force. To understand how that mass comes about, we need to better understand not only the average distribution of sea quarks and gluons within the proton and heavy ions, but to reveal the fluctuations in the fields and particle locations within. The key to that is deep inelastic scattering, and we’re well on our way to uncovering the cosmic truths behind the origin of matter’s mass.

Manganese Dendrites on Limestone

Locality: Solnhofen, Bavaria, Germany

“The earth as seen from the moon.” The young astronomer; or, Helps to a knowledge of the leading constellations. 1891.

cube

Quantum tunnelling

Tunneling is a quantum mechanical effect. A tunneling current occurs when electrons move through a barrier that they classically shouldn’t be able to move through. In classical terms, if you don’t have enough energy to move “over” a barrier, you won’t. However, in the quantum mechanical world, electrons have wavelike properties. These waves don’t end abruptly at a wall or barrier, but taper off quickly. If the barrier is thin enough, the probability function may extend into the next region, through the barrier! Because of the small probability of an electron being on the other side of the barrier, given enough electrons, some will indeed move through and appear on the other side. When an electron moves through the barrier in this fashion, it is called tunneling.

Quantum mechanics tells us that electrons have both wave and particle-like properties. Tunneling is an effect of the wavelike nature.

The top image shows us that when an electron (the wave) hits a barrier, the wave doesn’t abruptly end, but tapers off very quickly - exponentially. For a thick barrier, the wave doesn’t get past.

The bottom image shows the scenario if the barrier is quite thin (about a nanometer). Part of the wave does get through and therefore some electrons may appear on the other side of the barrier.

Because of the sharp decay of the probability function through the barrier, the number of electrons that will actually tunnel is very dependent upon the thickness of the barrier. The current through the barrier drops off exponentially with the barrier thickness

Source: nanoscience.com | Images: x | x | x

A movie showing the dynamics of the inner part of the Crab Nebula made using the Chandra X-ray Observatory.

Credit: NASA/CXC/ASU/J.Hester et al.