Saturday, 28 November 2009

Saturn's auroras put on a dazzling show

Cassini has spotted the tallest known "northern lights" in the solar system, flickering in shape and brightness high above the ringed planet.

"The auroras have put on a dazzling show, shape-shifting rapidly and exposing curtains that we suspected were there, but hadn't seen on Saturn before," said Andrew Ingersoll of the California Institute of Technology in Pasadena, who is a member of the Cassini imaging team that processed the new video. "Seeing these things on another planet helps us understand them a little better when we see them on Earth."

Auroras occur on Earth, Jupiter, Saturn and a few other planets, and the new images will help scientists better understand how they are generated. Auroras appear mostly in the high latitudes near a planet's magnetic poles. When charged particles from the magnetosphere -- the magnetic bubble surrounding a planet -- plunge into the planet's upper atmosphere, they cause the atmosphere to glow. The curtain shapes show the paths that these charged particles take as they flow along the lines of the magnetic field between the magnetosphere and the uppermost part of the atmosphere.


Rainbow trapped for the first time

Catching rainbows: a magnifying lens & a plate of glass, has been used to trap a rainbow for the first time.

New Scientist reports that when Vera Smolyaninova of Towson University in Baltimore, Maryland, and colleagues shone a multi-wavelength laser beam at the open end of a gilded waveguide, a trapped rainbow formed inside. This could be seen as a series of coloured rings when the lens was viewed from above with a microscope: the visible light leaked through the thin gold film.

"I think it's beautiful that we can create such complex phenomena using a very, very simple configuration," says Smolyaninova. "It's amazing."


Tuesday, 24 November 2009

Quantum Gravity Decouples Space & Time

Can unzipping the fabric of spacetime & harking back to 19th century notions of time yield a theory of quantum gravity?

Scientific American reports that there's a buzz about a quantum gravity theory that could send space and time back to their Newtonian roots.

Physicists have struggled to marry quantum mechanics with gravity for decades. In contrast, the other forces of nature have obediently fallen into line. For instance, the electromagnetic force can be described quantum-mechanically by the motion of photons. Try and work out the gravitational force between two objects in terms of a quantum graviton, however, and you quickly run into trouble—the answer to every calculation is infinity.

But now Petr Hořava, a physicist at the University of California, Berkeley, thinks he understands the problem. It’s all, he says, a matter of time. More specifically, the problem is the way that time is tied up with space in Einstein’s theory of gravity: general relativity. Einstein famously overturned the Newtonian notion that time is absolute—steadily ticking away in the background. Instead he argued that time is another dimension, woven together with space to form a malleable fabric that is distorted by matter. The snag is that in quantum mechanics, time retains its Newtonian aloofness, providing the stage against which matter dances but never being affected by its presence. These two conceptions of time don’t gel.

The solution, Hořava says, is to snip threads that bind time to space at very high energies, such as those found in the early universe where quantum gravity rules. “I’m going back to Newton’s idea that time and space are not equivalent,” Hořava says. At low energies, general relativity emerges from this underlying framework, and the fabric of spacetime restitches, he explains.


Monday, 23 November 2009

Rethinking Light and Sound

The director of the Census for Marine Life - Jesse Ausubel - rethinks how illumination and noise are rippling through ecosystems.
In his invited essay for Seed Magazine, he notes:

"When their generation looked up at the night sky a century ago, they saw swathes of stars. Today, however, our most familiar starry image may be satellites and astronauts looking down, observing the lights on Earth at night ...

I wonder if some of the changes experts attribute to carbon dioxide and global warming may owe more to nocturnal photons and their associates"

"... humans are adding about three decibels more sound to the ocean each decade, roughly doubling the power of the added noise. Because sound spreads widely in the oceans, human clamor touches every corner. ...As I wonder about life in a darker night, I wonder about marine life in a quieter ocean."


Friday, 20 November 2009

Eschatologists, man your engines!

The LHC is about to become operational again, more than a year after it's shut down.

To celebrate, The Register round up some of the most entertaining conspiracy theories circulating around the vast matter-rending machine faster than the protons it's meant to be accelerating. Amongst the gems assembled are:

"Dr Sergio Bertolucci - one of the top scientists at CERN - [says] that the LHC may in fact create a gateway to other dimensions. Through this dimensional portal might come "something", according to Bertolucci - or through it things from our own native four-dimensional universe might pass into some mysterious other continuum." ...


Tuesday, 17 November 2009

LHC getting closer to restart

Take a look at CERN during the lead-up to the restart of the LHC with a video posted in the CERN Bulletin.

The LHC operations teams are preparing the machine for circulating beams and things are going very smoothly. ALICE and LHCb are getting used to observing particle tracks coming from the LHC beams. During the weekend of 7-8 November, CMS also saw its first signals from beams dumped just upstream of the experiment cavern.


Sunday, 15 November 2009

Before inflation, before the Big Bang ..

"Before inflation, before the Big Bang ... you get into branes and the cyclic universe", Sean M. Carroll interviewed by Edge magazine.

"Inflation does not provide a natural explanation for why the early universe looks like it does unless you can give me an answer for why inflation ever started in the first place. That is not a question we know the answer to right now. That is why we need to go back before inflation into before the Big Bang, into a different part of the universe to understand why inflation happened versus something else. There you get into branes and the cyclic universe. ... I really don't like any of the models that are on the market right now. We really need to think harder about what the universe should look like."

Sean M. Carroll is a theoretical physicist, is a senior research associate at Caltech. Cofounder and contributor to the Cosmic Variance blog, his research interests include theoretical aspects of cosmology, field theory, and gravitation. He is the author of a Spacetime and Geometry: An Introduction to General Relativity; and From Eternity to Here: The Quest for the Ultimate Theory of Time. He is a frequent commentator on theoretical physics within the media.