# high energy particle physics

8

## How To Prove Einstein’s Relativity For Less Than \$100

“But the fact that you can see cosmic ray muons at all is enough to prove that relativity is real. Think about where these muons are created: high in the upper atmosphere, about 30-to-100 kilometers above Earth’s surface. Think about how long a muon lives: about 2.2 microseconds on average. And think about the speed limit of the Universe: the speed of light, or about 300,000 kilometers per second. If you have something moving at the speed of light that only lives 2.2 microseconds, it should make it only 0.66 kilometers before decaying away. With that mean lifetime, less than 1-in-10^50 muons should reach the surface. But in reality, almost all of them make it down.”

Relativity, or the idea that space and time are not absolute, was one of the most revolutionary and counterintuitive scientific theories to come out of the 20th century. It was also one of the most disputed, with hundreds of scientists refusing to accept it. Yet with less than \$100 and a single day’s worth of labor, there’s a way you can prove it to yourself: by building a cloud chamber. An old fishtank, some 100% ethyl or isopropyl alcohol, a metal base with dry ice beneath it and only a few other steps (see the full article for instructions) will allow you to construct a detector capable of seeing unstable cosmic particles. Yet these particles – and you’ll see about 1-per-second – would never reach Earth’s surface if it weren’t for relativity!

Come learn how you can validate Einstein’s first great revolution all for yourself, and silence the doubts in your mind. Nature really is this weird!

## Spin-2 Dark Matter Project: so it begins!

My new dark matter work extends my leptophobic graviton work: hence I’ve already developed many of the massive spin-2 computational tools I’ll need for new calculations. Today mostly involved

• outlining a procedure of attack
• dividing that procedure into subgoals and a timeline
• filling in computational gaps

Pictured above (left): Derivation of the spin-2 + scalar pair Feynman rule
Picture above (right): Summarizing all relevant Feynman rules

Dear highly acclaimed physics trash, I just read that researchers at Washington State University created a fluid with negative mass that accelerates backwards when force is applied to it. What are the potential future ramifications or opportunities presented by this?

So: I can’t get the full text of the paper which leaves me with news articles which aren’t super helpful. Hopeful it will be in the next Physics Today magazine, which I do get.

Probably even less helpful is the fact that I have never taken fluid dynamics in my life. I did undergrad research in cosmology and later high energy particle physics (in which I wrote my bachelor’s thesis) and then I moved towards medical physics which is mostly about radiation and magnetism. So basically I spent no time in my many years of schooling studying this. Weird, right?

All that aside, the articles indicate that even the researchers kind of don’t understand exactly why it happens (we’ve had superfluids before - helium can be superfluid at very low temperatures and do awesome stuff like flow uphill, but we haven’t seen anything quite like this). So ramifications are tough. That said it sounds like they’ll use this to research such things as dark matter and dark energy which we also don’t understand.

(and now you see why I went into applied physics. I have nothing but admiration and respect for people who spend their lives theorizing about physics but it would drive me up the wall. Kind of like supercooled helium.)

Dark matter and dark energy are basically theories to explain why the universe has a lot less mass and energy than it should. Lest this sound crazy, less than 150 years ago Mendeleev predicted various atomic elements through sheer interpolation between other elements in the table, even though they’d never been seen. Even more recently, Bohr developed the quantum model of the hydrogen atom by saying “well, this shouldn’t work unless quantization of the energy levels is true so I guess this thing I made up to make atoms make sense is true now”. And both those guys were right but we didn’t prove it until later. Anyway, people who study dark matter and dark energy theorize that perhaps they act like giant weird superfluids IN SPACE so now that we’ve made the weirdest superfluid so far, it seems like a good lab substitute for, you know, the far reaches of the universe.

So in short: I have no idea! Most of the people who actively worked on this project only have kind of an idea! Maybe something to do with space?

That’s basically what a lot of physics is. This has also given me a really good March for Science poster idea for this weekend so thank you for the ask!

It’s like art class! All we do is talk about color and draw!
—  High Energy Particle Physics Student
10

## Ask Ethan: Why is there a limit to what physics can predict?

“Why are there these units (Planck units) which you can’t further divide?”

There are fundamental limits to the Universe, in the sense that there are scales where our laws of physics break down. You can’t break matter or energy up into infinitely small pieces, and the same goes – we think – for space and time. But is that necessarily all true, and is that what the Planck scale means? Not quite. Rather, these are scales at which our laws of physics stop giving reliable predictions, as we make these mass, energy, length and time scales out of three constants fundamental to our physical theories: the gravitational constant, the speed of light and Planck’s constant. They do have strong physical implications, but they don’t necessarily mean these scales can’t be divisible further. After all, every particle in existence has a mass far below the Planck mass!

10

## What Are The Most Energetic Particles In The Universe?

“The fastest protons — the ones just at the GZK cutoff — move at 299,792,457.999999999999918 meters-per-second, or if you raced a photon and one of these protons to the Andromeda galaxy and back, the photon would arrive a measly six seconds sooner than the proton would… after a journey of more than five million years! But these ultra-high-energy cosmic rays don’t come from Andromeda (we believe); they come from active galaxies with supermassive black holes like NGC 1275, which tend to be hundreds of millions or even billions of light years away.”

When it comes to the Universe, you might think that energy really is only limited by rarity: get enough particles accelerated by enough supermassive, super-energetic sources, and it’s only a matter of time (and flux) before you get one that reaches any arbitrary energy threshold. After all, we’ve got no shortage of, say, supermassive black holes at the hearts of active galaxies. And yes, we do find cosmic rays hundreds, thousands or even millions of times the energy that the LHC can achieve. But when we think about the Universe in detail, these cosmic rays aren’t unlimited in their energy, but are rather stopped in their tracks by the most unlikely of sources: the ultra-low-energy cosmic microwave background, left over some 13.8 billion years after the Big Bang.

6

Will the LHC be the end of experimental particle physics?

“It’s no stretch to predict that you’re going to see a flurry of articles, presentations and talks over the coming few years on the topic of, “Have we found the first signs of particle physics beyond the Standard Model?”

And if the answer is, “not definitively,” have this be the takeaway: the Standard Model might be all our particle colliders can access in our lifetime. ”

At the end of the 19th century, Lord Kelvin famously said, “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” He was talking about how Newtonian gravity and Maxwell’s electromagnetism seemed to account for all the known phenomena in the Universe. Of course, nuclear physics, quantum mechanics, general relativity and more made that prediction look silly in hindsight. But in the 21st century, the physics of the Standard Model describes our Universe so well that there truly may be nothing else new to find not only at the LHC, but at any high-energy particle collider we could build here on Earth.

Spaceballs 3, the search for new physics. We ain't found shit.

Experimental High Energy Particle Physics PhD, University of California

4

Last day in Geneva highlights shown abot include(top left to bottom right):
Border between France and Switzerland
The LHCb detector, the large hadron collider at CERN
An out of operation detector that we were allowed to get really close to.

It was really really fun.

WORLD’S MOST POWERFUL DIGITAL CAMERA SEES CONSTRUCTION GREEN

The Large Synoptic Survey Telescope’s ‘Eye’ Will be Built at SLAC.

The Department of Energy has approved the start of construction for a 3.2-gigapixel digital camera – the world’s largest – at the heart of the Large Synoptic Survey Telescope (LSST). Assembled at the DOE’s SLAC National Accelerator Laboratory, the camera will be the eye of LSST, revealing unprecedented details of the universe and helping unravel some of its greatest mysteries.

The construction milestone, known as Critical Decision 3, is the last major approval decision before the acceptance of the finished camera, said LSST Director Steven Kahn: “Now we can go ahead and procure components and start building it.”

Starting in 2022, LSST will take digital images of the entire visible southern sky every few nights from atop a mountain called Cerro Pachón in Chile. It will produce a wide, deep and fast survey of the night sky, cataloguing by far the largest number of stars and galaxies ever observed. During a 10-year time frame, LSST will detect tens of billions of objects—the first time a telescope will observe more galaxies than there are people on Earth – and will create movies of the sky with unprecedented details. Funding for the camera comes from the DOE, while financial support for the telescope and site facilities, the data management system, and the education and public outreach infrastructure of LSST comes primarily from the National Science Foundation (NSF).

The telescope’s camera – the size of a small car and weighing more than three tons – will capture full-sky images at such high resolution that it would take 1,500 high-definition television screens to display just one of them.

This has already been a busy year for the LSST Project. Its dual-surface primary/tertiary mirror – the first of its kind for a major telescope – was completed; a traditional stone-laying ceremony in northern Chile marked the beginning of on-site construction of the facility; and a nearly 2,000-square-foot, 2-story-tall clean room was completed at SLAC to accommodate fabrication of the camera.

“We are very gratified to see everyone’s hard work appreciated and acknowledged by this DOE approval,” said SLAC Director Chi-Chang Kao. “SLAC is honored to be partnering with the National Science Foundation and other DOE labs on this groundbreaking endeavor. We’re also excited about the wide range of scientific opportunities offered by LSST, in particular increasing our understanding of dark energy.”

Components of the camera are being built by an international collaboration of universities and labs, including DOE’s Brookhaven National Laboratory, Lawrence Livermore National Laboratory and SLAC. SLAC is responsible for overall project management and systems engineering, camera body design and fabrication, data acquisition and camera control software, cryostat design and fabrication, and integration and testing of the entire camera. Building and testing the camera will take approximately five years.

SLAC is also designing and constructing the NSF-funded database for the telescope’s data management system. LSST will generate a vast public archive of data—approximately 6 million gigabytes per year, or the equivalent of shooting roughly 800,000 images with a regular 8-megapixel digital camera every night, albeit of much higher quality and scientific value. This data will help researchers study the formation of galaxies, track potentially hazardous asteroids, observe exploding stars and better understand dark matter and dark energy, which together make up 95 percent of the universe but whose natures remain unknown.

“We have a busy agenda for the rest of 2015 and 2016,” said Kahn. “Construction of the telescope on the mountain is well underway. The contracts for fabrication of the telescope mount and the dome enclosure have been awarded and the vendors are at full steam.”

Nadine Kurita, camera project manager at SLAC, said fabrication of the state-of-the-art sensors for the camera has already begun, and contracts are being awarded for optical elements and other major components. “After several years of focusing on designs and prototypes, we are excited to start construction of key parts of the camera. The coming year will be crucial as we assemble and test the sensors for the focal plane.”

The National Research Council’s Astronomy and Astrophysics decadal survey, Astro2010, ranked the LSST as the top ground-based priority for the field for the current decade. The recent report of the Particle Physics Project Prioritization Panel of the federal High Energy Physics Advisory Panel, setting forth the strategic plan for U.S. particle physics, also recommended completion of the LSST.

“We’ve been working hard for years to get to this point,” said Kurita. “Everyone is very excited to start building the camera and take a big step toward conducting a deep survey of the Southern night sky.”

### The Other Net

The first nationwide computer research network was the Defense Department’s ARPAnet, which evolved into the modern internet. But it wasn’t the last network of its kind. In 1976, the Department of Energy sponsored the creation of the Magnetic Fusion Energy Network to connect what is today the National Energy Research Scientific Computing Center with other research laboratories. Then the agency created a second network in 1980 called the High Energy Physics Network to connect particle physics researchers at national labs. As networking became more important, agency chiefs realized it didn’t make sense to maintain multiple networks and merged the two into one: ESnet.

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