Friday, Feb. 21, 2014

Have a safe day!

Friday, Feb. 21

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Matteo Cremonesi, INFN and University of Pisa, and Reinhard Schwienhorst, Michigan State University
Title: Observation of S-Channel Single-Top-Quark Production at the Tevatron

Monday, Feb. 24

2 p.m.
Particle Astrophysics Seminar - Curia II
Speaker: Katrin Heitmann, Argonne National Laboratory
Title: Large-Scale Structure Formation with Massive Neutrinos

3:30 p.m.

4 p.m.
All Experimenters' Meeting - Curia II

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a weekly calendar with links to additional information.

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Wilson Hall Cafe

Friday, Feb. 21

- Breakfast: potato pancakes
- Breakfast: Chorizo and egg burrito
- Texas Pete buffalo-style wings
- Smart cuisine: chana masala
- Tuna noodle casserole
- Honey mustard ham and Swiss panino
- Chicken fajitas plate
- Tomato basil bisque
- Texas-style chili
- Assorted pizza by the slice

Wilson Hall Cafe menu
Chez Leon

Friday, Feb. 21
- Roasted cherry tomato salad
- Pecan-crusted halibut with dijon cream sauce
- Wilted spinach
- Potato and onion gratin
- Lacy fruit cup with saboyan sauce

Wednesday, Feb. 26
- Shrimp and sausage gumbo
- Mixed green salad
- Bread pudding

Chez Leon menu
Call x3524 to make your reservation.


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Physics in a Nutshell

Mixed metaphors

When people first encounter an idea, they often frame it as a combination of previously understood ideas, like the sea-horse on the left. The reality (right) may be a different thing altogether.

This is the third in a four-part series on quantum mechanics. Previously, I discussed the discrete yet multivalued nature of quantum properties and the fact that quantum cause-and-effect need not be forward in time. Another oddity of quantum particles is that they are sometimes waves, not particles, though this is an altogether different kind of paradox.

While physicists were discovering quantum mechanics, they had already been debating whether matter and light are made of hard, indivisible particles or fluid waves. Early guesses by Democritus and Isaac Newton favored particles, but by the turn of the 20th century, there was strong evidence that light is a wave. These conceptual categories, "particle" and "wave," are based on experiences with everyday things like pebbles and water, generalized by mathematical abstraction. It is amazing how broadly applicable these simple ideas are to a wide range of natural phenomena, but both fail to describe what matter does at its smallest scales. Quarks, electrons and the rest are neither waves nor particles. They are another thing entirely.

The particle-like aspect of quantum objects is that they may entirely interact when they collide or they may entirely miss each other. This is what little rocks do when they're thrown at each other: They hit or they miss. It would be very strange for a wave to work this way. Imagine making a splash in Virginia Beach, watching the wave spread out across the Atlantic Ocean, and then seeing the full splash hit someone in Cape Town, Lisbon, Plymouth, Reykjavik or some other single place along the African or European coast. And yet light, which has clear wave-like properties, does entirely hit or entirely miss when individual photons collide.

The wave-like aspect of quantum objects is that they tend to spread out. Moreover, they can overlap each other and sometimes cancel each other out, like carefully timed waves. It's difficult enough imagining two pebbles occupying the same space at the same time, stranger still to imagine them becoming zero pebbles in the place where they overlap. Electrons engage in this kind of behavior.

Though often framed as a paradox, these properties are not inconsistent with one another, just never seen together at macroscopic scales. Our human notions of particle and wave are both inadequate for the microscopic world. The best metaphor that I think captures the behavior of quantum objects is the splash that propagates across the Atlantic and pops up with full force in some single (random) place. Unlike the time paradoxes, this aspect of quantum mechanics does not push us to the limits of what is conceivable — we just have to approach it with the willingness to make new metaphors.

Next week, I'll present uncertainty in quantum mechanics and the experiments that tell us that the universe we live in is a quantum universe.

Jim Pivarski

Photos of the Day

Fermilab participates in AAAS

Fermilab participated in this year's annual meeting of the American Association for the Advancement of Science, which took place in Chicago from Feb. 13-17. View a photo gallery of Fermilab employees talking about the lab's scientific and education programs and entertaining kids with hands-on demos. Photo: Reidar Hahn
In the News

Physicist-turned-filmmaker captures seven years of "Particle Fever"

From PBS NewsHour, Feb. 19, 2014

On July 4, 2012, physicists at the Large Hadron Collider in Switzerland announced that they had discovered the Higgs boson, the elusive particle that scientists hoped would explain why all matter has mass. News cameras rolled as the physicists popped open champagne.

What the public didn't see were the years of stress, joys and frustrations that accompanied the efforts of the Large Hadron Collider. But theoretical physicist David Kaplan and physicist-turned director Mark Levinson followed the drama that unfolded since the collider went live in 2008, capturing 500 hours of film in seven years. Using professional film crews and physicists armed with cameras, "Particle Fever" captures the sheer excitement the moments before the collider first turned on and the distress in the control room when a helium leak brought research to a temporary stop. Theoretical physicists feared they would never see proof that this particle, the lynchpin of the standard model of particle physics, existed.

We caught up with Kaplan this week at a screening of the film at the National Science Foundation.

Read more

In the News

Baby universe rumbled with thunder of Higgs bubbles

From New Scientist, Feb. 19, 2014

Bubbles popping in the hot particle soup that filled the early universe may have created a rumble like thunder, and it is possible that we can detect the echoes today. Finding them could help solve some mysteries of the Higgs boson and maybe lead to new physics.

Read more

Frontier Science Result:
Dark Energy Survey

Cosmic shadows in the microwave light from the big bang

Left: A South Pole Telescope image of the Sunyaev-Zel'dovich effect. The effect shows as a shadow in the cosmic microwave background from a cluster of galaxies. Right: This optical cluster image is a close-up from the Dark Energy Survey of the 2 x 2 arcmin red inset in the South Pole Telescope image on the left.

The cosmic microwave background is the radiant heat left over from the big bang. It was emitted nearly 14 billion years ago, just 380,000 years after the big bang, and has traveled across literally the entire observable universe. This makes the CMB an ideal backlight to find the most massive, distant structures in the universe, in particular clusters of galaxies.

The most massive clusters consist of over 1,000 galaxies and have a total mass larger than 1 million billion suns. Even with its relatively impressive heft, when CMB photons pass through a cluster, only about 1 percent scatter off of gas in the cluster, but this is enough to create a distinctive "shadow" in the CMB, usually known as the Sunyaev-Zel'dovich effect.

Clusters of galaxies are the largest gravitationally bound objects in the universe and are therefore important tracers of cosmic structure growth. The abundance of clusters over the history of the universe gives information about a variety of cosmological parameters, including the properties of dark energy. Earlier in the universe's history, dark energy affected the abundance of clusters primarily through its effect on the growth of structure in the universe. Therefore, the abundance of clusters probes the dark-energy paradigm in a way that complements geometric probes such as the light from supernovae.

The South Pole Telescope (SPT) and the Dark Energy Survey (DES), designed to find clusters of galaxies, are conducting overlapping surveys of the southern sky. The SPT finds a cluster through its distinctive shadow in the cosmic microwave background. DES finds clusters more traditionally by looking for over-densities of galaxies in optical images.

Each survey, which is designed to provide the largest catalog ever of massive, distant clusters, has an unprecedented combination of depth and area. The two methods have a strong complementarity and, in combination, are expected to provide significantly improved constraints on the evolution of dark energy via its effect on the growth of structure of the universe.

The DES survey recently finished its first year of a five-year survey on Feb. 9. Preliminary analyses of a subset of the DES data have already yielded a cluster catalog with nearly 1,000 clusters. The SPT measurements of the Dark Energy Survey clusters show the distinctive shadows in the cosmic microwave background expected from the Sunyaev-Zel'dovich effect. Even with this early data, the measurements confirm that: 1) DES is successfully finding very massive, distant clusters and 2) the SPT is measuring the distinctive cluster shadow in the cosmic microwave background with a spectral distortion at the level expected from theory.

The data is just a sign of things to come from the final survey, confirming the power of the South Pole Telescope and Dark Energy Survey data sets to find and characterize clusters and giving us a powerful new tool for understanding dark energy.

Bradford Benson

This plot shows a South Pole Telescope measurement of the Sunyaev-Zel'dovich effect of 602 DES-selected galaxy clusters. The clusters are sorted based on the number of galaxies in them: smaller, average and massive clusters. The SPT measurements are consistent with the distinctive SZ spectrum showing a shadow in the cosmic microwave background at low frequencies.

Today's New Announcements

Fermilab Natural Areas annual meeting - Feb. 25

Lunch and Learn: BCBS, Prime Therapeutics online tools - Feb. 26

Butts & Guts registration due Feb. 28

Deadline for on-site summer housing requests - March 3

URA Visiting Scholars Program deadline - Feb. 24

Zumba Fitness registration due Feb. 25

Zumba Toning registration due Feb. 27

Direct from Ireland: Alan Kelly Gang - Fermilab Arts Series - March 1

Interaction Management course - March 6, 13 and 20

Rembrandt Chamber Players - Gallery Chamber Series - March 9

Performance Review course: March 26 or 27

Society of Philosophy Club

Martial arts

International folk dancing meets Thursday evenings at Kuhn Barn

Scottish country dancing meets Tuesday evenings at Kuhn Barn

Indoor soccer

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