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.

2015 Roundup

Previous years: 2014, 2013, 2012, 2011, 2010. Cool things hopefully coming to this space in 2016. In the meantime, SCIENCE!

Ghost particles.

The McGurk effect is an audiovisual illusion that works even when you know how it works. It shows that understanding speech is visual as well as auditory.

True-color composite of Pluto and its moon Charon.

Jamais vu, the evil twin brother of deja vu.

A few amusing math terms, including surreal numbers and the Cox-Zucker Machine.

The solar eclipse of March 20, 2015. Wow, has it been that long already?

How many words for snow do the Eskimos have? Answer: not as many as you think.

God’s number and the Rubik’s Cube.

Trading in futures in a feudal Japanese rice market.

Quite a few of you have been messaging me using the new messaging system on Tumblr. I can’t respond to all of you if all you say is “hi”–honestly, what did you expect? But if you have any feedback on what you’d like to see here, feel free to do so. See you in 2016, may it be another great year for science!

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hannahhaifisch

7 years ago

How Spheres Impact Water Has Been Studied For More Than A Century. The Typical Impact For A Rigid Sphere

How spheres impact water has been studied for more than a century. The typical impact for a rigid sphere creates a cavity like the one on the upper left - relatively narrow and prone to pinching off at its skinny waist. If the sphere is elastic –squishy – instead, the cavity ends up looking much different. This is shown in the upper right image, taken with an elastic ball and otherwise identical conditions to the upper left image. The elastic ball deforms; it flattens as it hits the surface, creating a wider cavity. If you watch the animations in the bottom row, you can see the sphere oscillating after impact. Those changes in shape form a second cavity inside the first one. It’s this smaller second cavity that pinches off and sends a liquid jet back up to the collapsing splash curtain.

From the top image, we can also see that the elastic sphere slows down more quickly after impact. This makes sense because part of its kinetic energy at impact has gone into the sphere’s shape changes and their interaction with the surrounding water.

If you’d like to see more splashy stuff, be sure to check out my webcast with a couple of this paper’s authors. (Image credits: top row - C. Mabey; bottom row - R. Hurd et al., source; research credit: R. Hurd et al.)

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hannahhaifisch

8 years ago