Cosmic to Quantum

christinetheastrophysicist: Theorists apply loop quantum...

Mon, 03 Jun 2013 01:38:53 -0400

Theorists apply loop quantum gravity theory to black hole

Physicists have published a study applying Loop Quantum Gravity to an individual black hole, showing that singularities – or the infinite strengthening of the gravitational field that occurs deep within a black hole, insuring the annihilation of anything entering – may not be encountered. Instead, their model shows that gravity would eventually change, suggesting that the “other end” of a black hole might take one to another location within our own universe.

Read More.

TEDxCERN multiplies dimensions

Fri, 31 May 2013 00:31:08 -0400

TEDxCERN multiplies dimensions:

christinetheastrophysicist:

Videos of the talks at TEDxCERN, many of which dealt with particle physics, are now available online.

cab1729: BBC News - Alpha Magnetic Spectrometer zeroes in on...

Wed, 03 Apr 2013 13:24:22 -0400

cab1729:

BBC News - Alpha Magnetic Spectrometer zeroes in on dark matter

A $2bn experiment on the space station has made observations that could prove to be the first signs of dark matter, a mysterious component of the Universe.

The Alpha Magnetic Spectrometer (AMS) surveys the sky for high-energy particles, or cosmic rays.

It has seen evidence of what may prove to be dark matter colliding with itself in what is known as “annihilation”.

But scientists stress a precise description of this mysterious cosmic component is still some way off.

“It could take a few more years,” AMS deputy spokesman Roberto Battiston, a professor of physics at the University of Perugia, told BBC News.

Dark matter accounts for most of the mass in the Universe.

It cannot be seen directly with telescopes, but astronomers know it to be out there because of the gravitational effects it has on the matter we can see.

Galaxies, for example, could not rotate the way they do and hold their shape without the presence of dark matter.

The AMS - a kind of particle accelerator and nicknamed the “space LHC” in reference to the Large Hadron Collider here on Earth - has been hunting for some indirect measures of dark matter’s properties.

The AMS counts the numbers of electrons and their anti-matter counterparts - known as positrons - falling on its detectors.

Theory suggests that showers of these particles should be produced when dark-matter particles collide somewhere in space and destroy each other.

In a paper to be published in the journal Physical Review Letters, the AMS team reports the observation of a slight excess of positrons in the positron-electron count - an outcome expected of these dark matter annihilations.

The group also says the positrons fall on the AMS from all directions in the sky with no particular variation over time.

This is important because specific locations or timing variations in the signal could indicate a more conventional source for the particles, such as a pulsar (a type of neutron star) rather than dark matter.

The AMS was placed on the International Space Station in 2011. The longer it operates, the better its statistics will be and the more definitive scientists can be in their statements.

The Physical Review Letters paper reports the positron-electron count in the energy range of 0.5 to 350 gigaelectronvolts (GeV).

The behaviour of the positron excess across this energy spectrum fits with the researchers’ expectations. However, the “smoking gun” signature would be to see a rise in this ratio and then a dramatic fall. This has yet to be observed.

“At the moment, all we can say is that the (dark matter) particles could have a mass of several hundred gigaelectronvolts, but there is much uncertainty,” said Prof Battiston. (By way of comparison, a proton, the particle in the nucleus of every atom, has a mass of about 1 GeV).

An extra dimension for LHCb The Standard Model of particle...

Tue, 02 Apr 2013 09:33:00 -0400

An extra dimension for LHCb

The Standard Model of particle physics is like a jigsaw into which physicists are gradually fitting pieces. Though most results fit well and are compatible with Standard Model predictions, there are physicists hoping for results that don’t fit the jigsaw and so could point to new physics.

Jonas Rademacker of the University of Bristol and the Large Hadron Collider beauty (LHCb) collaboration is one of those physicists. “We’re hoping to find the jigsaw piece that looks like it should fit, but when you look very closely, the pattern isn’t quite right,” he says.

Rademacker has developed a new way of analysing data from LHCb that offers an unprecedented level of detail and precision. His technique requires analyzing special scatter plots called Dalitz plots in five dimensions rather than two. These plots represent the strange quantum-mechanical interference effects that happen in particle decays, and Rademacker and his colleagues use them at LHCb as a precision tool to measure CP violation.

Though five-dimensional analysis is a complicated feat, it is worth the effort because it significantly increases the precision of LHCb measurements.

Read More

By: Stephanie Hills

staceythinx: These space colony concept drawings were the...

Sat, 30 Mar 2013 08:55:26 -0400

staceythinx:

These space colony concept drawings were the result of collaboration between Princeton physicist Gerard O’Neill, the NASA Ames Research Center and Stanford University in the 1970’s. They held a series of space colony summer studies which explored the possibilities of humans living in giant orbiting spaceships.

cab1729: For There We Are Captured—-The Geometry of...

Wed, 27 Mar 2013 17:16:28 -0400

cab1729:

For There We Are Captured—-The Geometry of Spacetime

What does it mean when we say spacetime is “curved” or “flat?”

The answer lies in the interface between differential geometry and physics.

understandingtheuniverse: thespacegoat: Courses:CourseraEDXUdac...

Tue, 26 Mar 2013 15:22:13 -0400

understandingtheuniverse:

thespacegoat:

Courses:
Coursera
EDX
Udacity
University of Reddit

Books:
Bartleby
Gutenberg
Librivox
Poem Hunter

Videos:
Academic Earth
C. G. P. Grey
Crash Course
Khan Academy
Minute Physics
The New Boston Tutorials
TED
Unplug the TV

Documentaries:
Documentary Heaven
Top Documentary Films

Languages:
BBC Languages
Busuu
Dou Lingo
Live Mocha
MemRise
Verbling

Music:
How to Play Piano
Justin Guitar
Music Theory
Play Bass Now
Teoria

Programming:
Code Academy
Coding Bat
HTML Dog
Learn Code the Hard Way
Ruby Monk
Trypython

DIY/How-To:
Howcast
How Stuff Works
Instructables
The Daily Miscellany
Wiki How
Wonder How-To

Math:
Math Run
Project Euler
Wolfram Alpha

Cooking:
Cooking for Engineers
Cooklet
How2Heroes
Reluctant Gormet

This is a great list but I want to add two more informative websites to it:

sixtysymbols (physics and astronomy)

numberphile (“videos about numbers and stuff”)

Parky's new brain: Has Julian Barbour solved the question of the origin of time?

Thu, 21 Mar 2013 08:40:24 -0400

Parky's new brain: Has Julian Barbour solved the question of the origin of time?:

rabraha3:

parkysnewbrain:

In his recent paper with Matteo Lostaglio and Flavio Mercati, Julian Barbour suggests a possible origin for the nature of time…

Julian Barbour is well known for being a advocate for the ‘Block Theory’ of time (or Eternalism), that is that time doesn’t really move, but rather already exists,…

Some responses/reactions by Lee Smolin (friend and collaborator of Barbour and Mercati):

Does Time Emerge from Timeless Laws, or do Laws of Nature Emerge in Time?

The Universe as a Process of Unique Events

These are video lectures (colloquia, really) given at the Perimeter Institute for Theoretical Physics. I have only seen the second one. Like people working on causal set theory (Sorkin, Dowker, and others), Smolin and collaborators consider causal relations to be a fundamental building block.

We always have to be careful. We can create bunches of models to give descriptions and predictions, but do they actually reflect reality? There was once a machine which showed the exact equivalence between the Ptolemaic and Copernican models for the solar system. With data before Brahe, the two models (earth- and sun-centered respectively) gave the same accuracy in the predictions.

This is somewhat in parallel to Barbour’s pet idea which has culminated in Shape Dynamics (by Koslowski, Gryb, Gomes). This is a physically very distinct theory from General Relativity yet are dynamically equivalent for parts of the theory — the two spaces of solutions have a non-trivial intersection. Locally, even, they are indistinguishable. They have the same solutions.

Is this a question about the uniqueness of mathematical descriptions of the universe? A commentary on the physical mechanisms at work?

amnhnyc: Have plans tonight? We’re live streaming the 2013...

Wed, 20 Mar 2013 17:08:40 -0400

amnhnyc:

Have plans tonight? We’re live streaming the 2013 Isaac Asimov Memorial Debate: The Existence of Nothing, hosted by Hayden Planetarium Director Neil deGrasse Tyson.

Tune in at amnh.org/live. The fun begins at 7:30 pm EST.

Image (c) AMNH/R. Mickens

atomstargazer: All About Elementary Particles First two images...

Wed, 20 Mar 2013 16:59:09 -0400

atomstargazer:

All About Elementary Particles

First two images

Third image

Fourth image

Fifth image

Six image

thenewenlightenmentage: Beyond Higgs: 5 Elusive Particles That...

Fri, 15 Mar 2013 15:21:40 -0400

thenewenlightenmentage:

Beyond Higgs: 5 Elusive Particles That May Lurk in the Universe

With the recent confirmation of a Higgs Boson discovery, many physicists were at least a little disappointed. That’s because all signs point to it confirming the Standard Model, the nearly 100-year-old theory that explains the tiny bits of matter that make up the universe.

But some physicists still hold out hope for results that could provide a bigger shake-up, looking for the Large Hadron Collider (LHC) and physics experiments at other facilities to reveal other hidden particles lurking in the universe. From gravitons to winos, here are five bizarre things that may exist beyond the Higgs:

Continue Reading

scienceisbeauty: Experimental set-up of the quantum...

Fri, 15 Mar 2013 14:13:02 -0400

scienceisbeauty:

Experimental set-up of the quantum teleportation device including an entangled light-emitting diode (ELED) and an assortment of beam splitters polarization controllers, detectors, and photodiodes.

Source: Quantum teleportation performed with light from a quantum dot embedded in an LED, Phys.Org

A Journey Into Extra Dimensions with Delia Schwartz-Perlov

Fri, 15 Mar 2013 14:02:56 -0400

Extra Dimensions
brought to you by Livescribe

Further Reading Recommended by The Nature of Reality:

Cosmos: Carl Sagan: The 4th Dimension
In this scene from the classic “Cosmos” series, Carl Sagan imagines what happens when a three-dimensional character enters a two-dimensional world.

FQXi: Taking on String Theory’s 10-D Universe with 8-D Math
In this article, discover how theorists Tevian Dray and Corinne Manogue are using ten-dimensional math to describe subatomic particles.

NOVA: Imagining Other Dimensions
Journey from a two-dimensional “flatland” to the ten- (or more) dimensional world of superstring theory in this illustrated essay.

About Delia Schwartz-Perlov

Delia Schwartz-Perlov is a Postdoctoral Fellow at the Tufts Institute for Cosmology. She studies cosmology, quantum field theory and general relativity, and has a special interest in the study of inflation, the multiverse and the string theory landscape. When she is not pondering the mysteries of the multiverse, she studies piano, yoga, and art.

Be sure to check out her other livescribe/article on the subject: A Tour Through the Multiverse!

christinetheastrophysicist: Physicists Discover 13 New...

Thu, 14 Mar 2013 22:34:20 -0400

christinetheastrophysicist:

Physicists Discover 13 New Solutions to Three-Body Problem

It’s the sort of abstract puzzle that keeps a scientist awake at night: Can you predict how three objects will orbit each other in a repeating pattern? In the 300 years since this “three-body problem” was first recognized, just three families of solutions have been found. Now, two physicists have discovered 13 new families. It’s quite a feat in mathematical physics, and it could conceivably help astrophysicists understand new planetary systems.

Read More.

wolframalpha: Happy Pi Day! Check out the the parametric...

Thu, 14 Mar 2013 09:51:18 -0400

wolframalpha:

Happy Pi Day!

Check out the the parametric equation required to make the Pi Curve — just a bit more complicated than the first 1000 digits of pi.

For more fun facts about pi, be sure to read a few of our old blog posts.

spaceplasma: atomstargazer: Extremely rare triple quasar...

Wed, 13 Mar 2013 12:39:29 -0400

spaceplasma:

atomstargazer:

Extremely rare triple quasar found

For only the second time in history, a team of scientists have discovered an extremely rare triple quasar system.

For only the second time in history, a team of scientists including Michele Fumagalli from the Carnegie Institution for Science in the United States have discovered an extremely rare triple quasar system. Their work is published in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

skeptv: Cosmic Journeys : Plasma Rockets & Solar...

Tue, 12 Mar 2013 11:31:16 -0400

skeptv:

Cosmic Journeys : Plasma Rockets & Solar Storms

Join a small team of rocket designers as they open a window into the future of space travel. Stirring music from Digital Republic.

Modern science has linked polar light shows, called auroras, to vast waves of electrified gas hurled in our direction by the sun. Today, researchers from a whole new generation see this dynamic substance, plasma, as an energy source that may one day fuel humanity’s expansion into space. What can we learn, and how far can we go, by tapping into the strange and elusive fourth state of matter?

Since the dawn of rocketry, we’ve relied on the same basic technology to get us off the ground. Fill a cylinder with volatile chemicals, then ignite them in a controlled explosion. The force of the blast is what pushes the rocket up. Nowadays, chemical rockets are the only ones with enough thrust to overcome Earth’s gravity and carry a payload into orbit. But they are not very efficient.

The heavier the payload, the more fuel a rocket needs to lift it into space. But the more fuel a rocket carries, the more fuel it needs. For long-range missions, most spacecraft rely on their initial launch speed to essentially coast to their destination. Flight planners often design routes that give the craft a gravity assist by sending it around the moon or another planet. One small cadre of scientists believes it has a quicker and more efficient way to get around in space.

Dr. Ben Longmier and his team from the University of Michigan have traveled to Fairbanks, Alaska to play a small part in a much larger push to revolutionize space travel and exploration.

The team plans to use helium balloons to send components of a new type of rocket engine to an altitude of over 30 kilometers, above 99% of Earth’s atmosphere. The purpose is to test these components within the harsh environment of space. While astronauts train to live and work in zero gravity, or to move around in bulky space suits, these would-be space explorers are preparing to negotiate some of Earth’s harshest environments.

Once they launch their payload, they have to retrieve it wherever it comes down in Alaska’s vast snowy wilderness. The idea they are pursuing is nothing short of revolutionary. It’s a type of rocket that promises far greater gas mileage than other rockets, and enough power to reach distant targets. It runs on the same fuel that nature uses, literally, to power the universe: plasma.

by SpaceRip.

Black Hole Spins at Nearly the Speed of Light A superfast black...

Sat, 09 Mar 2013 16:07:17 -0500

Black Hole Spins at Nearly the Speed of Light

A superfast black hole nearly 60 million light-years away appears to be pushing the ultimate speed limit of the universe, a new study says.

For the first time, astronomers have managed to measure the rate of spin of a supermassive black hole—and it’s been clocked at 84 percent of the speed of light, or the maximum allowed by the law of physics.

“The most exciting part of this finding is the ability to test the theory of general relativity in such an extreme regime, where the gravitational field is huge, and the properties of space-time around it are completely different from the standard Newtonian case,” said lead author Guido Risaliti, of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF-Arcetri Observatory in Italy. (Related:“Speedy Star Found Near Black Hole May Test Einstein Theory.”)

Notorious for ripping apart and swallowing stars, supermassive black holes live at the center of most galaxies, including our own Milky Way. (See black hole pictures.)

They can pack the gravitational punch of many million or even billions of suns—distorting space-time in the region around them, not even letting light escape their clutches.

Galactic Monster

The predatory monster that lurks at the core of the relatively nearby spiral galaxy NGC 1365 is estimated to weigh in at about two million times the mass of the sun, and stretches some 2 million miles (3.2 million kilometers) across—more than eight times the distance between Earth and the moon, Risaliti said. (Also see “Black Hole Blast Biggest Ever Recorded.”)

Risaliti and colleagues’ unprecedented discovery was made possible thanks to the combined observations from NASA’s high-energy x-ray detectors on itsNuclear Spectroscopic Telescope Array (NuSTAR) probe and the European Space Agency’s low-energy, x-ray-detecting XMM-Newton space observatory.

Astronomers detected x-ray particle remnants of stars circling in a pancake-shaped accretion disk surrounding the black hole, and used this data to help determine its rate of spin.

By getting a fix on this spin speed, astronomers now hope to better understand what happens inside giant black holes as they gravitationally warp space-time around themselves.

Even more intriguing to the research team is that this discovery will shed clues to black hole’s past, and the evolution of its surrounding galaxy.

Tracking the Universe’s Evolution

Supermassive black holes have a large impact in the evolution of their host galaxy, where a self-regulating process occurs between the two structures.

“When more stars are formed, they throw gas into the black hole, increasing its mass, but the radiation produced by this accretion warms up the gas in the galaxy, preventing more star formation,” said Risaliti.

“So the two events—black hole accretion and formation of new stars—interact with each other.”

Knowing how fast black holes spin may also help shed light how the entire universe evolved. (Learn more about the origin of the universe.)

“With a knowledge of the average spin of galaxies at different ages of the universe,” Risaliti said, “we could track their evolution much more precisely than we can do today.”

Andrew Fazekas

for National Geographic News

Published March 1, 2013

(Image: An artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our sun.

Illustration courtesy Caltech/NASA)

thespacegoat: Hubble Images are Produced, Not Taken Images...

Thu, 07 Mar 2013 17:34:45 -0500

The individual raw black and white Hubble images are opened and scaled.

Images are aligned in a graphics editing program.

The camera that took this image is made of two light detectorsm separated by a gap. The gaps are filled with data from another camera.

Each image is assigned a color. Combined, they create a full color image.

Cosmetic defects, including bad pixels, cosmic rays and the detector gap, are cleaned.

The color composite is rotated and cropped.

thespacegoat:

Hubble Images are Produced, Not Taken

Images must be woven together from the incoming data from the cameras, cleaned up and given colors that bring out features that eyes would otherwise miss. In this video from HubbleSite, a Hubble-imaged galaxy comes together on the screen.

(Astro)Physics: Time and the basic physics principle

Thu, 28 Feb 2013 09:16:18 -0500

(Astro)Physics: Time and the basic physics principle:

rabraha3:

That was not a typo. I will discuss the principle upon which modern physics is based: Maupertuis’ Principle. I rather like this instead of Hamilton’s Principle for reasons of time… They aren’t quite the same, but very nearly. I like to summarize it to my students that nature is inherently lazy. These two principles are often called the principle of least action (kind of a misnomer, as is my summary: the action is actually only extremized). They are similar in spirit to Fermat’s principle — light rays take the path which minimizes the time of travel. Nature wants to get things over with. The name “action” evokes a laziness of nature, then, when minimizing the action. For our current purposes, the distinction between Maupertuis and Hamilton is not necessary.

Really, we want to find the trajectory of a particle through the space of states. This tells us the location and momentum of the particle at any time in the future. We start with two states, an initial and final, and we consider a path between them. Along the path, we evaluate the action and add it all up. Find the path which this sum is the smallest. So it isn’t quite like the minimization of a geodesic length, but close. Perhaps later we can draw more formal analogy, but I’ll work with the loose one for now.

We can move forward and backwards on this trajectory. Physics doesn’t care, the sum of the action on the path doesn’t care. If we lay a preferred direction down, however, suddenly forward and backwards become distinguished (unless the trajectory happened to lie everywhere perpendicular to this preferred direction). Such is the case in Finsler geometry [the wiki entry isn’t very helpful]. The distance depends on which way you are moving.

We know of such cases. Consider two points at different elevations on the same side of a mountain. Generally it takes a much longer time going up the mountain versus going down the mountain. Planes take longer going against a headwind than flying with a tailwind, even though it is going to the same place. Such is the result of a preferred direction, such is the case in Finsler geometry.

So what if the space of states has a preferred direction? Can this start the explain the arrow of time? Does the arrow make sense to define for single particles, or is it an emergent phenomenon born out of the collection of large numbers of particles?

To make things nice, we can have a preferred direction following the integral curves of the vector field generated by the Hamiltonian, pulled back via the inverse of the Legendre transformation onto configuration space. But that is for another time (and can we make it spontaneously generated)?