Physics & Astronomy News

<p>Interference pattern created by neutron holography.</p>


Holograms from Neutrons Created
For the first time, scientists have used neutron beams to create holograms of large solid objects, revealing details about their interiors in ways that ordinary laser light-based visual holograms cannot.
<p>An artist’s conception of this unusual system, courtesy of Jonathan Holden/Disk Detective.</p>
Oldest Known Planet-Forming Disk Found
Scientists find a star surrounded by the oldest known circumstellar disk—a primordial ring of gas and dust that orbits around a young star and from which planets can form.

<p>Mars’ Valles Marineris canyon, pictured, spans as much as 600 kilometers across and delves as much as 8 kilometers deep. The image was created from over 100 images of Mars taken by Viking Orbiters in the 1970s.</p>

<p>Image: NASA</p>
New Technique May Help Detect Martian Life
A novel interpretation of Raman spectra will help the 2020 Mars rover select rocks to study for signs of life.
<p>Simplification to represent PT (Parity-Time) symmetry. Imagine a situation where two cars are traveling at the same speed at some instant in time, but car A is speeding up, and car B is slowing down. In order to go at the same speed, you can jump from one car to the other (Parity reversal) and back in time (Time reversal). The cars are like the light waves inside the fiber, the speed of the cars is a representation of the intensity of light and the jump symbolizes a phenomenon called tunneling. (Graphics modified from freepiks).</p>
Stable Propagation of Light in Nano-Photonic Fibers
New model on how to achieve a more stable propagation of light for future optical technologies was published.

Quantum Effects Observed in ‘One-Dimensional’ Wires
Researchers have observed quantum effects in electrons by squeezing them into one-dimensional ‘quantum wires’ and observing the interactions between them.
Echoes of Black Holes Eating Stars Found
Astronomers now have new insights into tidal disruption flares, thanks to data from NASA's Wide-field Infrared Survey Explorer (WISE).
Individual Atoms Behavior Observed
For first time, researchers see individual atoms keep away from each other or bunch up as pairs.

Science Facts

Dark Energy Changes the Universe

by NASA Headquarters and

The diagram at right shows the changes in the rate of expansion since the universe Dark energy has the cosmoslogists scratching their heads. Observations taken by NASA's Hubble Space Telescope and future space telescopes will be needed in order to determine the properties of dark energy, which makes up about 70 percent of the universe. Probing dark energy, the energy in empty space causing the expanding universe to accelerate, calls for accurately measuring how that expansion rate is increasing with time. Dark energy is thought to drive space apart. Astronomers used NASA's Hubble Space Telescope to hunt for supernovae (an energetic explosive event that occurs at the end of a star's lifetime), using their brightness, astronomers could measure if the universe was expanding faster or slower in the distant past. In its search, Hubble discovered 42 new supernovae, including six that are among the most distant ever found.

The farthest supernovae show that the universe was decelerating long ago, but then 'changed gears' and began to accelerate. Albert Einstein coined the term 'cosmological constant' to represent the possibility that even empty space has energy and couples to gravity. Like other astronomers of the time, he thought that the universe was static and so proposed there was a repulsive force from space that kept the universe in balance. Einstein discarded his own findings in 1929, when Edwin Hubble found through his research that the universe was expanding and not static. Today, new data from Hubble may well prove Einstein was on the right track. The pull of gravity and the push of dark energy have been trying to outmuscle each other since the beginning of time. About seven billion years ago, dark energy got the upper hand because the universe had grown so large and matter (the source of gravity) had expanded and scattered.

Cosmologists believe about 70 percent of the universe consists of dark energy, 25 percent is dark matter, and only four percent normal matter (the stuff that stars, planets and people are made of). Hubble observations suggest the dark energy may be Einstein's cosmological constant, an energy percolating out of the vacuum of the space between galaxies. The energy of the universe is dominated by empty space emitting a repulsive form of gravity that is pushing the universe apart. But what does all this mean to Earth? Even if Einstein's theory was correct, we won't have to be concerned about the 'dark side' for about 30 billion years, according to Hubble researchers.

Without buoyancy, the vapor produced by boiling simply floats as a bubble inside the liquid after the heating has stopped. Surface tension effects cause the many small bubbles produced to coalesce into one large sphere.
Bizarre Boiling

The next time you're watching a pot of water boil, perhaps for coffee or a cup of soup, pause for a moment and consider: what would this look like in space? Would the turbulent bubbles rise or fall? A ...
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Astronaut in free fall
Can You Miss the Earth?

Have you ever wondered why astronauts float in space? Well, it isn't because there is no gravity in space. Astronauts float because they are in constant free fall. If a baseball pitcher throws a ba ...
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Look, Up in the Sky. It's A Bird. No It's A Meteorite!

Most folks probably think of swallows and the ringing of the Mission bells when the words San Juan Capistrano are heard or seen. This is a popular tradition that celebrates the return of cliff swallow ...
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