Astronomy and Physics News around the World Dec. 09, 2012
Reported News for this Week:
1. 5 Reasons We May Live in a Multiverse
2. Ultrafast light turns insulator into a conductor 3. Do We Really Need Dark Matter?
4. 77 year old Einstein, Podolsky, and Rosen proposition extended to 3 particles
5. “Overview:” The Perspective-Altering Effect of Seeing Earth from Space 6. X-ray vision can reveal the moment of birth of violent supernovae
7. Point of light
8. Below surface, moon reveals a "shattered" history 9. Cosmic radio waves mimic chirping of "alien birds"
10. Organic metamaterial flows like liquid
5 Reasons We May Live in a Multiverse
The universe we live in may not be the only one out there. In fact, our universe could be just one of an infinite number of universes making up a "multiverse."
Though the concept may stretch credulity, there's good physics behind it. And there's not just one way to get to a multiverse — numerous physics theories independently point to such a conclusion. In fact, some experts think the existence of hidden universes is more likely than not. More
Ultrafast light turns insulator into a conductor
The electronic properties of silica changed from an insulator to a conductor when hit with an intense femtosecond laser pulse. When a thin silica-glass film (black frame in the center) is exposed to ultrafast light pulses (red), the strong optical field changes the electronic states in the glass with each cycle of its oscillation. These variations were tracked in real time by a series of "snapshots" recorded by attosecond light pulses (blue) passed through the sample.
The recording of the instantaneous state of the electronic system of the probed sample allows researchers to reconstruct the field-induced changes.
Optics & Photonics News - In a duo of Nature papers, physicists have shown that very intense
femtosecond laser pulses can induce electrical currents in fused silica prism without doing damage to the material. Fused silica is normally an insulator. That it can quickly be changed into conductors (and back into insulators again) could be used for signal switching. Today's fastest semiconductor switching is measured in terahertz. But light-induced switching in insulators, such as demonstrated in these papers, could work at petahertz rates. Results in the first Nature paper demonstrate that a strong-field femtosecond pulse can induce a current in the dielectric on a very short timescale. But demonstration that the current can be turned off on the same time scale is shown in the second paper. Taken together the results show that the
current-producing effect is nonlinear, but predictable, and that it is reversible and producible on interesting timescales. MORE
Do We Really Need Dark Matter?
Hubble mosaic of massive galaxy cluster MACS J0717.5+3745, thought to be connected by a filament of dark matter. Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM) Even though teams of scientists around the world are at this very moment hot on the trail of dark matter – the “other stuff” that the Universe is made of and supposedly accounts for nearly 80% of the mass that we can’t directly observe (yet) — and trying to quantify exactly how so-called “dark energy” drives its ever- accelerating expansion, perhaps one answer to these ongoing mysteries is maybe they don’t exist at all.
This is precisely what one astronomer is suggesting in a recent paper, submitted Dec. 3 to Astrophysical Journal Letters.
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Read the rest of Do We Really Need Dark Matter? (600 words)
77 year old Einstein, Podolsky, and Rosen proposition extended to 3 particles
To verify entanglement among the three photons, the physicists measured the times that the photons arrived at a detector. This 2D histogram shows that groups of three photons are all localized to a small region, indicating strong correlations in the arrival times of the three photons. Image credit: L. K. Shalm, et al. ©2012 Macmillan Publishers Limited
Physorg.com - In a 1935 Physical Review paper, Einstein, Podolsky, and Rosen proposed a thought
experiment that pondered what happens with two initially interacting systems are allowed to separate and not interact. Their conclusion was that there was some lingering interaction between the systems, encoded in some hidden variables, and that the wave function is an incomplete description of reality. Debate on the so-called 'EPR paradox' continues to this day. In work recently published in Nature Physics, physicists have extended the EPR experiment from two systems to three, and notably with continuous variables of those systems instead of discrete variables. To achieve this feat the researchers split a pump laser beam into two daughter beams, and then split one of the daughters. The total energy is conserved between the parent beam and the daughters. The emission times of the parents and daughters, which correspond to position, are also conserved. Thus energy and position, which are continuous variables, amongst the photons are correlated. This new demonstration will have several applications in quantum communications in addition to being a tool to further ponder the foundations of quantum mechanics. MORE
“Overview:” The Perspective-Altering Effect of Seeing Earth from Space
For over 40 years, the ‘Blue Marble’ images of Earth taken from space have provided a new perspective of our planet, and the sometimes life-altering experience of such views was described in Frank White’s book
“The Overview Effect,” published in 1987. When it came out, I gobbled it up, and have since read it several times.
Today, on the 40th anniversary of the final launch of the Apollo missions to the Moon, a new short film
“Overview” has been released, which explores this phenomenon through interviews with five astronauts who have experienced first-hand seeing Earth from space.
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Read the rest of “Overview:” The Perspective-Altering Effect of Seeing Earth from Space (265 words)
X-ray vision can reveal the moment of birth of violent supernovae
A team of astronomers led by the University of Leicester in the U.K.has uncovered new evidence that suggests that X-ray detectors in space could be the first to witness new supernovae that signal the death of massive stars. The possibility stems from the finding that gamma-ray bursts from the largest supernovae are accompanied unique thermal X-ray signatures that can be observed by detectors now in place.
Read/Comment
Point of light
As technology advances, it tends to shrink. From cell phones to laptops—powered by increasingly faster and tinier processors—everything is getting thinner and sleeker. And now light beams are getting smaller, too. Engineers at the California Institute of Technology have created a device that can focus light into a point just a few nanometers across—an achievement they say may lead to next-generation applications in computing, communications, and imaging. Read/Comment
Below surface, moon reveals a "shattered" history
This artist rendering released by NASA shows the twin spacecraft Ebb and Flow orbiting the moon. The duo found evidence that the moon’s interior is more battered than previously thought and the crust is thinner than expected. AP
Photo/NASA
Results presented Wednesday at the American Geophysical Union meeting in San Francisco show that the moon took a beating in its early days, far more than previously believed. Detailed gravity mapping by NASA's Ebb and Flow spacecraft show the extent to which the moon was broken up and shattered from bombardment by asteroids and comets. Read/Comment
Cosmic radio waves mimic chirping of "alien birds"
This undated image made available by NASA and the Goddard Space Flight Center shows an artist's rendition of the Van Allen Probes in orbit around Earth. The twin spacecraft have captured the clearest sounds yet from Earth's radiation belts—and they mimic the chirping of birds. NASA's Van Allen Probes have been exploring the hostile radiation belts surrounding Earth for just three months. But already, they've collected measurements of high-energy
particles and radio waves in unprecedented detail. Scientists said Tuesday, Dec. 4, 2012 these waves can provide an energy boost to radiation belt particles, somewhat like ocean waves can propel a surfer on Earth. AP
Photo/NASA/Goddard Space Flight Center
NASA's Van Allen Probes have been exploring the hostile radiation belts surrounding Earth for just three months. But already measurements in unprecedented detail have been taken. Scientists said Tuesday these waves can provide an energy boost to radiation belt particles, somewhat like ocean waves can propel a surfer on Earth. What's more, these so-called chorus waves operate in the same frequency as human hearing so they can be heard. Read/Comment
Organic metamaterial flows like liquid
Hydrogels made in the form of the letters D, N, and A collapse into a liquid-like state on their own but return to the original shape when surrounded by water.
A bit reminiscent of the Terminator T-1000, a new material created by Cornell University researchers is so soft that it can flow like a liquid and then, strangely, return to its original shape. Rather than liquid metal, it is a hydrogel, a mesh of organic molecules with many small empty spaces that can absorb water like a
sponge. It qualifies as a "metamaterial" with properties not found in nature and may be the first organic metamaterial with mechanical metaproperties. Read/Comment
