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Summer Physics Bundle

Byron — Wed, 29 Jun 2011 14:24:43 PDT

Summer Physics Bundle

This bundle includes all 23 blogs from students for Summer Physics 2011 at SI.

Ajlouny
Cotroneo
Fox
Summer Physics
Brendan
Izzo
Soberanis
Hess
Vierra
Gavin
Kelvin Cheung
Craft
Keighran
Tillinghast
Mannix
Tullis
Schurr
Qaqish
LaRocca
Summer Physics!
Summer Physics
Metoyer
Stricker
Seher

Preview this bundle

Summer Phys 2011

Byron — Mon, 27 Jun 2011 15:53:10 PDT

Summer Phys 2011

Summer Physics Bundle

Ajlouny
Cotroneo
Fox
Brendan
Izzo
Soberanis
Hess
Vierra
Gavin
Kelvin Cheung
Craft
Keighran
Tillinghast
Mannix
Tullis
Schurr
Qaqish
LaRocca
Summer Physics!
Summer Physics
Metoyer
Stricker
Seher

Preview this bundle

Milestones for the Tevatron and LHC

John — Sat, 18 Jun 2011 12:42:18 PDT

This past week saw two big milestones for the two big operating high energy particle colliders in the world. At these machines, we measure the number of collisions with the rather arcane unit of “inverse barns”, which is essentially a measure of inverse cross sectional area. It’s just like if you are throwing darts at a dart board across the room with your eyes closed: the bigger the dart board, the more likely you are to hit it, and the more darts you throw, the more hits you get.

The term “barn” came from the early days of nuclear physics when Fermi quipped that a nucleus is “as big as a barn.” And so a new physics unit was born: one barn is 10^-28 m², about the size of a big nucleus. At the Tevatron at Fermilab, we’ve just crossed over 10.0 inverse femtobarns of integrated luminosity, after over ten years of operation in what we call Run 2 of the Tevatron. At the LHC at CERN, we just saw the integrated luminosity counter roll over to 1.000 inverse femtobarns. It’s kind of like the difference between your 10-year old car rolling over to 100,000 miles, and your new year-old car rolling over to 10,000 miles.

Our old car, the Tevatron, has taken us on quite a ride this past decade. I’ll push the analogy further, though, and say that it’s been like driving across the Great Plains. We kept hoping to see mountains, but it’s been flatland the whole way. Though we’ve looked very hard, we just have not turned up any sign of new physics at this incredible machine, despite the recent excitement. The present schedule is that the Tevatron will collide its last proton and antiproton at 2:00 pm on September 30 of this year. We’re tradin’ her in.

With our new car, the LHC, expect to see the mountains very soon, and in fact we reached this amount of data far sooner than I would have predicted at the beginning of the year. Last year, starting in March and eventually stopping in early November, the LHC delivered 0.04 inverse femtobarns, 25 times less than the sample we have now. But that was the first good chunk of physics data, and an army of data-hungry students, postdocs, lab scientists and professors analyzed it frantically over the winter, publishing a huge torrent of papers in the spring as the LHC really started to hit the gas. (Okay, perhaps the analogy is stretching to the breaking point here.)

So are the white things on the horizon we are starting to see the snow-capped peaks we have hoped for, or just clouds? We’ll soon know, and this is bound to be a summer to remember in the history of particle physics, unlike any time since the “November Revolution” of 1974, when the charm quark and the tau lepton made their appearance at the Stanford Linear Accelerator and Brookhaven National Lab.

After the November Revolution, with the third generation of quarks and leptons established, the Standard Model took solid form: there soon followed the discovery of the bottom quark at Fermilab in 1977, the gluon at DESY in Hamburg in 1979, and the W and Z bosons at CERN in 1982. The hunt for the top quark and the Higgs boson, and whatever might lie beyond, was on.

But it took another thirteen years to find the top quark, and in 1995, the CDF and D0 experiments did just that at the Tevatron. It was clear as a bell, and surprisingly massive, weighing in at nearly the mass of a gold atom at 175 GeV. With the precise measurements of the W and Z from CERN it soon became clear that the Higgs might just lie within reach of the Tevatron, which could discover it before the LHC could be completed. (The SSC had been cancelled in 1993 in a budget climate eerily like our own.)

And so Run 2 of the Tevatron began in 2001 after major upgrades to both experiments. Slow at first, the accelerator luminosity steadily increased, and the physics flowed, with better and better measurements of the top quark and W boson, and searches for the Higgs and a host of other hypothetical particles. Two years ago the Tevatron experiments finally reached the level where, combined, the data from CDF and D0 ruled out the HIggs boson if its mass were twice that of the W boson, 160 GeV. But no sign of any new particles.

The data from the LHC in 2010 was not sufficient to improve upon this Higgs search result. In a wide swath of other physics studies, however, the LHC is surpassing the Tevatron. Basically, the LHC should be viewed as a gluon collider: a gluon in one incoming proton collides with a gluon from another, producing whatever gluons produce when they do this, which is anything that is strongly interacting (that is, feels the strong nuclear force). Even with over a factor of a hundred less integrated luminosity, the LHC can do far more than the Tevatron due to the LHC’s higher energy. But at the LHC as well, last year, there was no sign of new physics.

In the coming weeks, though, with the huge new data set, the LHC will blow past the Tevatron in nearly every category except in the search for the low mass Higgs boson, where there truly still is a race. There are two big conferences coming up at the end of July, in Boston and Grenoble, France, at which we can expect the announcements of any discoveries made by the LHC experiments CMS and ATLAS…or by the Tevatron. Fasten your seat belts!

Observations of a first-time AP exam reader

Dean Baird — Sat, 18 Jun 2011 17:40:24 PDT

...as shared on the AP Physics EDG by James von Steen, physics teacher at Southwest Guilford High School in High Point, North Carolina. His note is reprinted here with the author's permission.

It's important to note that the author's intent is not to deride test-takers for common mistakes, but rather to describe the observations he made as a first-time AP Physics exam reader (grader).

After a 5 year wait, I final received the opportunity to become an AP reader. My primary goal was to learn as much as I possibly can to become a better teacher. Here are things I noted.

1. A lot of students thought that work is always positive (never negative).

2. A lot of students thought W = F x t , W = F / d , W = F x v and F = mat.

3. If a student put down the correct numerical answer, but showed no work, they could get 0 pts and 1 pt at most.

4. A student could have math errors and still get maximum points.

5. On an FBD, if the directions say “on the dot below” draw the force vectors …., If the student draws force vectors that don’t touch the dot (even though they are correctly labeled and pointed in the correct direction), they could lose credit (I learned this one at the lunch table).

6. Readers don’t like grading the lab question.

7. I’m going to tell my students when “Justification” is requested, use formulas and calculations to justify your answer as oppose to words. The more words they write the more likely the reader is going to over look a correct answer. Example: W = F x d = -15 J (easy to spot and give credit) as oppose to ”Work equals forces times distance which will be a negative numbers” (hard to spot especially embedded in a lot of text). I looked back now and wonder if I missed giving some desiring students credit.

8. Don’t use the word “it”. I don’t know what “it” is. I saw students write “it is decreasing”. I don’t know if “it” meant acceleration, velocity or my bank account after the children are born.

9. A lot of students thought work was a vector.

10. Watch out for the decimal point in the given. The problem was given 0.40 kg and a lot of students wrote F = ma = (4)(2) = 8 N and missed an easy point.

11. “Check” the box(es). Some students didn’t do any work but checked the correct spaces and got credit and (sadly) one student got no credit because he/she check no boxes even though they stated the correct box to be checked and had the correct justification (we have to go by the rubric).

12. I thought that the students didn’t have to memorize any numbers, but the only way to answer the very last problem of the exam 6. d) ii) is they had to memorize the wavelengths of visible light. I was told it is in the “acorn” book, but I couldn’t find it. Which makes me think that there are other numbers out there that my students are require to memorize.

13. It looks like the AP Physics redesign will be a step backwards. I didn’t hear anybody liking it public or privately. I’m luckier than most. I’m able to get the whole curriculum in but my students will take 2 exams for 6 hours instead of 1 exam for 3 hours (and yes they paid for both). I can see the redesign killing some AP physics programs and overall less students taking the exam.

14. The food was “ok” (not as great as I heard it was). I got tired of recycled green beans, lettuce and potatoes every day.

15. I met a lot of smart people that I learned from. I hope they ask me back next year.

Responses to von Steen's post indicated some variation of interpretation among readers. But the variations were relatively subtle.

You tend to see things when you're a wide-eyed first-timer that you don't always see when you're a sage veteran. And this first-timer was willing to share. Students might appreciate these insights as they go into the exam in May.

Lightning Eclipse from the Planet of the Goats

(author unknown) — Sat, 18 Jun 2011 22:25:14 PDT

Thunderstorms almost spoiled this view of the spectacular June 15

SPIDER: Probing the Early Universe with a Suborbital Polarimeter. (arXiv:1106.3087v1 [astro-ph.CO])

Thu, 16 Jun 2011 22:38:07 PDT

We evaluate the ability of SPIDER, a balloon-borne polarimeter, to detect a divergence-free polarization pattern ("B-modes") in the Cosmic Microwave Background (CMB). In the inflationary scenario, the amplitude of this signal is proportional to that of the primordial scalar perturbations through the tensor-to-scalar ratio r. We show that the expected level of systematic error in the SPIDER instrument is significantly below the amplitude of an interesting cosmological signal with r=0.03. We present a scanning strategy that enables us to minimize uncertainty in the reconstruction of the Stokes parameters used to characterize the CMB, while accessing a relatively wide range of angular scales. Evaluating the amplitude of the polarized Galactic emission in the SPIDER field, we conclude that the polarized emission from interstellar dust is as bright or brighter than the cosmological signal at all SPIDER frequencies (90 GHz, 150 GHz, and 280 GHz), a situation similar to that found in the "Southern Hole." We show that two ~20-day flights of the SPIDER instrument can constrain the amplitude of the B-mode signal to r<0.03 (99% CL) even when foreground contamination is taken into account. In the absence of foregrounds, the same limit can be reached after one 20-day flight.

Girafa

nobody@flickr.com (Justin.Beck) — Thu, 16 Jun 2011 20:11:26 PDT

Justin.Beck posted a photo:

Peak Facebook?

(author unknown) — Mon, 13 Jun 2011 22:12:42 PDT

Three weeks ago I observed that Google trend data indicated that <a ...

Why the universe wasn't fine-tuned for life

(author unknown) — Tue, 14 Jun 2011 04:38:00 PDT

In The Fallacy of Fine-tuning, Victor Stenger dismantles arguments that the laws of physics in our universe were "fine-tuned" to foster life

Managing iOS Devices in the Classroom #tatc11

Wesley Fryer — Fri, 10 Jun 2011 08:53:13 PDT

These are my notes from Maria Henderson's presentation on using iOS devices (specifically the iPad) at the TCEA Area 7 Technology Conference on 10 June 2011:
http://moodle.tcea.org/area7conference/

(I GOT TO THIS SESSION A LITTLE LATE. MY THOUGHTS AND COMMENTS ARE IN ALL CAPS.)

It is so important to talk about more than apps, managing devices in the classroom is critical

Bretford cart only certifies that a Mac / Apple computer (not a Windows machine) to charge and sync multiple iOS devices
http://apple.bretford.com/products/mobilitycart

Important for teachers to create a home base for students to start from at school and at home
- could be a wiki page, a Moodle page, etc
- this is where students go for files, handouts, content, etc

Maria's site: http://server.iteachdigital.com
- this is a list of wikis for workshops I teach

http://71.164.176.4/groups/

- using a wiki is word processing on the fly

My idea playground is where I go to play with lots of sites, apps, etc

Accessibility feature of iPad as three finger, double tap to zoom in
- turn that on in iPad settings

Have you realized there is no "save" button on the iPad?
- the button in Safari on the iPad is "Share" not save
- this mirrors change we want to see in schools, we don't live in silos, we need to share more

Every time my 14 year old prints he is finished with that work, it is dead to him
- digital documents can be different

Make your webpage an app by clicking the share button in Safari and choose "Add to Home Screen"

Syncing your devices to the cart is sometimes not as spontaneous as learning can be when you use a wiki
- you can distribute links, ebooks, more this way
- great to use the cloud

Isn't it crazy that the iPad has just been out ONE year?
- every day there are new opportunities for what we use

If you are going to do a widespread implementation of iPads, it is a really good idea to get all your students their own email accounts
- use email as a tool to distribute content

(MY THOUGHT: THIS IS SO TRUE AND A GOOD REASON FOR SCHOOLS TO ADOPT GOOGLE APPS FOR THEIR DOMAIN!)

You can create a free account on box.net and have an email address students use to turn in their assignments - this is storage in the cloud
- kids just have to know an email address to turn in their work, each folder you have has it's own unique address

http://box.net/

THIS IS A WONDERFUL TIP!!! Evernote is like a digital trapper keeper

http://evernote.com

Volume purchase plan makes it much easier for each device to have it's own license for each app

Proloquo2go is an expensive app schools are buying ($190)
- can replace a technology that costs $8000 - $10,000
http://www.proloquo2go.com/About/article/ipad

Organization CK12 is resource for open source textbooks
- you can search for CK12 in iTunes to find these

http://www.ck12.org/flexbook/

Text in an eBook is "reflowable"

PDFs favor form over function
- the way it looks is more important than working with the document

ePubs favor function over form

All media must be in line when creating an ePub Apple has a free template for Pages available, which is good to use when creating ePubs
- this support page from Apple has great info on ePubs

http://support.apple.com/kb/ht4168

Sent from my iPad

Posted via email from wesley fryer's posterous

Google’s Web-Only Chromebook Now Available for Pre-Order

Mike Isaac — Fri, 10 Jun 2011 10:19:18 PDT

Samsung debuted its version of the Chromebook in May. Photo: Michael Calore/Wired.com

Google announced on Thursday that its web-only laptop, the Chromebook, is now available for pre-order in the United States via Best Buy or Amazon websites.

Google’s Chromebook hardware is currently offered by two manufacturers — Samsung and Acer — with two different product designs. Both manufacturers are offering Wi-Fi only and 3G versions of the device.

“Nothing but the web,” Google Chrome’s Twitter account wrote Thursday evening, linking followers to the sale page. Chromebook pre-orders ship on June 15.

As a web-only device, the Chromebook fits in perfectly with Google’s vision of a cloud-based future. Essentially, the Chromebook takes the netbook and strips it of the components found in most laptop computers. There’s no visible operating system outside of Google’s Chrome browser (hence the name), which means the interface is entirely web-based. There’s also no significant local storage (though it does have a removable SD card slot), which means everything you’re using on the device must be stored and accessed remotely from online servers.

Of course, Google’s cloud-based vision has you covered there. Want access to your photos? Upload them to Picasa, Google’s photo storage site. Hankering for music? Google Music (now in beta) stores all your music on the internet, streaming songs to the device. The same goes for documents (Google Docs), calendars (Google Calendar) and most other things you could think to use on your netbook.

Acer’s cutely titled “Cromia” comes with an 11.6-inch HD display, 6-hour battery life, and weighs just under 3 pounds. The Wi-Fi only version costs $380, and the Verizon-carried 3G version comes priced at $450.

Samsung’s model comes with a bump up in features, as well as a boost in price. The display is larger by about an inch, and it’s a little heavier at 3.1 pounds. But Samsung says its Chromebook gets an added 2.5 more hours of battery life than Acer’s slightly cheaper model. Samsung’s model will start at $430 for Wi-Fi, and $500 for a 3G version.

Google first debuted the Chromebook at the company’s developer-centric event in May, Google I/O.

An Alice-in-Wonderland universe? Physicist discovers an apparent cosmic parity violation

(author unknown) — Fri, 10 Jun 2011 09:56:56 PDT

Does our universe have mirror symmetry? That is the question physicist Michael Longo asked. The answer could perhaps be found by studying the rotation directions of spiral galaxies.

EDWARD Electric Diwheel Is Like a Sci-Fi Bike

Charlie Sorrel — Fri, 10 Jun 2011 04:34:11 PDT

EDWARD would be more at home at a carnival than on the road

If Ripley’s Power Loader from Aliens was mated with a bicycle, it would look like the EDWARD Project. EDWARD is a diwheel. That is, it’s a vehicle with both its wheels axially aligned, instead of one in front of the other like a bike.

EDWARD is a product of a team of students at the University of Adelaide, Australia. Here’s a video of it in action.

As you can see, EDWARD is electric. The motors in the wheels are controlled by a joystick, and this means that, by spinning them in opposite directions, you can quite literally turn on a dime (or over a dime, should you put one beneath the machine). You can also lock the wheels to the chair with a handbrake, which will spin the rider along with the wheels for some hot, nausea-inducing action.

The first part of the video shows the EDWARD in action without its computer brain engaged. Switching in the control mechanism prevents the lurching — or “gerbiling” — of the seat and also allows some neat tricks: riding updide-down, for instance.

After watching this video, there are two things of which I am sure. One is that I totally want to take EDWARD for a spin. Second is that I would never, ever do it after a heavy lunch.

The EDWARD project [University of Adelaide via Oh Gizmo!]

See Also:

Geoff Marcy: Mission to Alpha Centauri

Paul Gilster — Fri, 10 Jun 2011 06:10:58 PDT

The Tau Zero Foundation is pleased to announce that planet hunter extraordinaire Geoffrey Marcy is now affiliated with the organization. As a Tau zero practitioner, Dr. Marcy will serve as a major point of contact on exoplanet issues, bringing with him the most storied portfolio in the planet-hunting business. Working closely with Paul Butler and Debra Fischer, Dr. Marcy (University of California at Berkeley) has discovered more extrasolar planets than anyone else, including 70 out of the first 100 to be found. His team’s findings include the first multiple-planet system, the first Saturn mass planets, and the first Neptune-mass planet. His awards are numerous: Shaw Prize in 2005, Discovery Magazine‘s Space Scientist of the Year in 2003, the NASA Medal for Exceptional Scientific Achievement, the Carl Sagan Award, the Beatrice Tinsley Prize, and the Henry Draper Medal from the National Academy of Sciences.

A warm welcome, Geoff!

Centauri Dreams readers will recall our coverage of the Next 40 Years of Exoplanets workshop at the Massachusetts Institute of Technology, where Geoff took up Sara Seager’s challenge to be provocative by taking on the powers that be at NASA, JPL and his own exoplanet community on behalf of Terrestrial Planet Finder and the lamented Space Interferometry Mission. He closed that session by making the case for a robotic mission to Alpha Centauri, a project that could in his judgment revitalize NASA and space agencies worldwide. Let me quote him on this:

“I’d like to make an appeal to President Obama. I think he should stand up and make the following announcement: That before the century is out we will launch a probe to Alpha Centauri, the triple star system, and return pictures of its planets, comets and asteroids, as soon as possible, even if it takes a few hundred years or a thousand years to get there. [Going to Alpha Centauri] would engage the K-12 children, it would engage every sector of our society… It would jolt NASA back to life, if we’re really lucky. And of course any such mission should be an international one involving Japan, China, India, Europe…”

Marcy went on to note that such a mission would bring not only scientific progress but the diplomatic coherence required as the world worked together toward this momentous common goal. In some ways, the call reminded me of Daniel Goldin’s days as NASA administrator, when just as the Pathfinder spacecraft was nearing Mars, he told reporters that building a robotic probe that could reach another star would become a NASA priority. Back then small steps were indeed taken. An Interstellar Probe Science and Technology Definition Team met at the Jet Propulsion Laboratory in early 1999 to consider the prospect, but budget realities and the daunting nature of the mission brought an early end to any organized effort within the agency.

Will Marcy’s call for an Alpha Centauri mission meet a better fate? We can hope so and continue to draw researchers together to work toward this end even as the exoplanet hunt continues. Marcy’s challenge at the MIT meeting was embedded within a discussion of the exoplanet field and its tools today, and it’s a good time to review the discussion (you can see Geoff’s talk by following this link to the MIT archives). The key to exoplanet research is getting the spectra needed to study these worlds, and Marcy said it was the nearby stars that offered the real, 40-year future of exoplanet research: “Habitable planets around the nearest stars, those within 25 light years, offer enormous advantages over those that orbit more distant stars.”

The advantages: Planets around nearby stars can be imaged, allowing spectroscopy. Proximity also allows us to measure the zodiacal dust around those stars, both to study the dust in its own right, but also to be able to subtract the dust signature to more clearly resolve an Earth-like planet. We can also measure the masses of planets around nearby stars through either Doppler or astrometric methods. “And frankly,” Marcy added, “the nearby stars are the ones reachable by next generation propulsion systems. So I think spectroscopy of the habitable planets around the nearest stars is really the forty year future.” Thus the need for instrumentation to be able to image and take spectra of Earth-sized planets at reasonable distances from their stars.

Marcy was candid about his anger with the recent decadal survey and NASA response. For the 2010 decadal survey, New Worlds, New Horizons in Astronomy and Astrophysics, was remarkable for what it didn’t include. The Terrestrial Planet Finder mission was not mentioned at all as a priority. The reasons are many but Marcy blames NASA headquarters, scientists at the Jet Propulsion Laboratory, and people within the exoplanet community including himself for not having made a strong enough case to ensure its survival. He calls Terrestrial Planet Finder ‘our human genome project,’ noting that “The different gene sequencing TPF sub-projects cancelled each other out. Coronagraphs killed the interferometers which killed the occulters and SIM was left squashed. The squabbling cost the field ten years, and TPF is officially zeroed out.”

But we still need space-borne interferometry, and an overwhelming case remains for the interferometric version of Terrestrial Planet Finder (TPF-I). Marcy says that free flying interferometers are the only plausible future for astrophysics, but competing designs were alternately funded and encouraged and then dropped, leaving proponents of each at war. I won’t go into all the specifics but send you instead to Marcy’s talk. Suffice it to say that all the presentations are worth hearing (the complete archive page is here), but Geoff’s call for an Alpha Centauri mission was what brought him into contact with the Tau Zero Foundation, and we’re honored by the chance to work with him in the future as studies of nearby stars including Alpha Centauri intensify.

knewdrew: reverse graffiti. instead of using actual spray...

(author unknown) — Sat, 04 Jun 2011 17:00:06 PDT

knewdrew:

reverse graffiti.

instead of using actual spray cans…some artist are just cleaning dirt off of certain areas to make their masterpieces. and they are calling it reverse graffiti. kind of brilliant.

The Sun lets loose a HUGE explosion

(author unknown) — Tue, 07 Jun 2011 09:21:52 PDT

Early this morning, the Sun erupted with an explosion I can only ...

MakerBot's Bre Pettis on Colbert Wednesday night

Cory Doctorow — Wed, 08 Jun 2011 04:55:09 PDT

Hoo-ah! I was at MakerBot in Brooklyn yesterday and they were all atwitter with the news that Bre Pettis, the face of the MakerBot open 3D printer and the Thingiverse 3D object repository, would be on Colbert Report ~~tonight~~ Wednesday night. Don't touch that dial!

Bre Pettis on The Colbert Report!

Hula Hoop-cam: The world goes for a spin

Dean Baird — Thu, 09 Jun 2011 05:18:44 PDT

The Go Pro is a small, light-weight camera capable of still photography and video capture. Here's what happens when you attach one to a Hula Hoop and attach the Hula Hoop to a skilled practitioner. Those inclined toward motion sickness should probably not go full-screen on this one. Everyone else? What are you waiting for!

Gyrational hula spins to PTSOSer Zeke Kossover and Exploratorium guru Paul Doherty.

DNA Takes Square Roots

(author unknown) — Fri, 03 Jun 2011 13:00:49 PDT

Around these parts we’ve been known to discuss whether it makes any ...

Handheld inkjet print gun

Rob Beschizza — Fri, 03 Jun 2011 19:12:07 PDT

As someone that your attorney will one day have to explain to the court, I advise you to procure the PrintBrush use-on-anything handheld inkjet printer as soon as it becomes available. [PrintDreams]