Tag Archives: cosmology

Got Change for an Electron?

Ella at the whiteboardIsraeli scientists have sliced electrons into “quasiparticles,” each with a quarter charge of the electron.

Although electrons are indivisible, if they are confined to a two-dimensional layer inside a semiconductor, chilled down to a fraction of a degree above absolute zero and exposed to a strong magnetic field that is perpendicular to the layer, they effectively behave as independent particles, called quasiparticles, with charges smaller than that of an electron.

Quasis have been known for 20 years, but they were “odd fractionally charged” — one third of an electron, one fifth, etc. The quarter-charges behave differently and may be useful for computing.

Those of us who have trouble wrapping our heads around quantum stuff might sympathize with astronomers, who, the New York Times tells us, are finding cosmology just as puzzling.

As far as astronomers can tell, there is no relation between dark matter, the particles, and dark energy other than the name, but you never know.

Nevertheless, string theorist Brian Greene, promoting the World Science Festival, reminds us of something most readers of this site would probably find a truism, but is probably a new idea to a lot of people:

We must embark on a cultural shift that places science in its rightful place alongside music, art and literature as an indispensable part of what makes life worth living.

[Ella Delivers Her Lecture on String Theory by Phillip C]

Telescope finds a void in the universe

The central darker region of the middle of this picture indicates something very strange is occuring…Following on from yesterday’s post about Hugh Everett and the ‘Many Worlds Interpretation’ of Quantum Physics, I came across this interesting article via Chris Mckitterick’s blog. NASA’s Wilkinson Microwave Anisotropy Probe(WMAP) has been studying the microwave emissions of the universe back towards the big bang. The Cosmic Microwave Background, or CMB, is more or less constant across the sky, a gradually cooling remnant of the beginning of our universe.

Earlier this year a vast region of space was detected where the CMB was a lower temperature. Further study showed that the area had very few stars or galaxies and was a much bigger empty space than predicted by any models. Some scientists think the hole is caused by a massive patch of dark energy. Others think that this region may be evidence of another universe, especially if a similar patch is found in the southern hemisphere of the sky.

[via Chris Mckitterick, image from Science Daily]

Oops, our bad: by observing the universe, we may have doomed it

DarkMatterPie-590 One of the weirdest aspects of quantum theory is the role of the observer: particles exist only as probabilities until they are observed, at which point they become definite. (Schrödinger’s neither-alive-nor-dead cat is the most famous thought experiment along these lines.) (Via EurekAlert!)

Now New Scientist is reporting that a pair of physicists at Case Western Reserve University in Cleveland, Ohio, suggest that when, in 1998, astronomers observed the light from supernovae and from that deduced the existence of dark energy, we may have reset the clock of the university universe to the state it was in early in its history, when it was more likely to just as suddenly cease to exist as it suddenly sprang into existence in the first place. (Image: NASA via Wikimedia Commons.)

We’re still here, so the universe hasn’t winked out of existence just yet. But any second now…

[tags]cosmology, astronomy, physics, quantum theory[/tags]

Solved: someone found those pesky missing Dwarf Galaxies

Circinus dwarf galaxy

Image courtesy of NASA via spacetoday

A big conundrum in astronomy and cosmology over the last ten years has been the ‘Missing Dwarf Galaxy’ Problem. Dwarf Galaxies are much smaller than normal galaxies and though this makes them fainter and harder to find, astronomers have still been finding far fewer than predicted. The prediction comes from the ‘Cold Dark Matter’ model. Dark matter, which is thought to make up around 22% of all substance in the universe compared to about 2-5% of the matter we can see, forms in distinct ‘halos’, in which real galaxies form. (The remaining 74% of energy density is the mysterious dark energy, responsible for the expansion of the universe.)

By studying the distribution of these dark matter halos, astronomers predicted that a large galaxy such as our own Milky Way should have a hundred or so smaller dwarf satellites. The problem is, until very recently only a handful had been seen. A lot of these could have no visible stars and it was difficult to see a way to detect them. Until now. Two astronomers using the W. M. Keck Observatory in Hawaii think they may have found a load more, possibly solving one of the biggest questions in our study of the stars.

Incidentally, the name for a galaxy smaller than a dwarf class is known as a hobbit galaxy. [via science daily]