November 29th, 2008 / 2 Comments
The Read head of a typical computer hard drive takes advantage of Giant Magnetoresistance to carefully read changes in the external magnetic field and therefore your desired data. Most people, however, don’t know that this process actually involves determining the spin of electrons. While most electronics simply communicate information by reading the charge, magnetic read heads communicate using the electron’s intrinsic magnetic field (spin). This is an example of spintronics.
What is Spintronics?
Yup it’s a combination of “spin” and “electronics.” However, it is also the basis for many of our electronic components today. Dr. Alan Drew from Queen Mary’s Department of Physics and the University of Freiburg, Switzerland and several colleagues decided to investigate exactly how spin travels through the read head [...]
Posted in: Condensed Matter
November 29th, 2008 / No Comments
Current Lithium Batteries
Almost all portable devices we use today are powered by rechargeable lithium ion batteries. Cell phones, iPods, Laptops, Cameras, and more depend on them. Everyone that uses these devices, though, realizes the importance of making sure you have properly charged the battery so as to get the maximum amount of battery life. Otherwise, one is out of luck when it comes time for that all-important presentation or entertainment on the bike ride home.
These batteries work by transferring lithium ions from the anode (usually made of graphite) to the cathode during discharge and from the cathode to the anode during recharge. First proposed by Whittingham in the 70s, these have become vital in our everyday lives. Although many advances have already been made in safety and transportability, battery life is still a limiting factor.
High Efficiency Lithium Batteries
Researchers at Hanyang University in Korea, led by Jaephil Cho, have discovered a new usable material for the Anode that could increase battery life dramatically. This material is [...]
Posted in: Atomic, Molecular, and Optical
November 28th, 2008 / No Comments
The Death of Earth
It is predicted that in about 5 billion years our Sun will expand into a Red Giant, consuming the inner planets and Earth! Assuming humankind lives to see this, or encounters similar situations in future colonial planets, planning is going to be crucial in order to survive such an event. While this may be far off, it is interesting to consider the situation.
Plan to save Earth
Taube and Seifritz recently suggested a plan that would allow us to steer clear of the enlarging fireball that [...]
Posted in: Astrophysics
November 28th, 2008 / 1 Comment
Metamaterials are artificial media that exhibit a wide range of extraordinary electromagnetic properties that are not found in nature. For example, a negative index of refraction was experimentally verified by R. Smith et al. in 2000 and R. A. Shelby et. al in 2001. Their papers suggest that infinite subwavelength resolution could be achieved by a class of materials, Left-Handed Metamaterials (LHMs). Furthermore, an electromagnetic cloak was experimentally demonstrated using this material by D. Schurig et al. in 2006. Their device used a series of concentric split ring resonators to achieve the desired permittivity and permeability required for a negative index of refraction, but was not effective in visible wavelength.
Recently submitted to arxiv.org is a paper by Christos Argyropoulos, Yan Zhao, and Yang Hao that makes use of these and following experiments to examine several ways that these types of electromagnetic cloaks could be modified to have perfect wave absorption [...]
Posted in: Atomic, Molecular, and Optical
November 28th, 2008 / No Comments
In my last post I mentioned N-body simulations for dark matter halos. These simulations require hundreds or thousands of hours on some of the most advanced supercomputers in the world. Massive computing power is also required in a large number of other pieces of contemporary research: the LHC, global warming, search for pulsars, various protein [...]
Posted in: General
November 28th, 2008 / 1 Comment
Hey just got done with some research. I’m doing a short review of modelling methods of Dark Matter Halos (DMHs). DMHs may account for up to 95% of a galaxy’s mass, making them a crucial component of our universe. Dark matter , however, does not interact with electromagnetic radiation and is invisible. Thus, it’s only evidence comes from gravitational observations seen between large-scale objects in the universe. DMHs are believed to consist of weakly-interacting massive particles (WIMPs) and/or massive compact Halo objects (MACHOs). It is essential to construct models of DMHs that account for current observations in order to predict other observable consequences.
N-body simulations are simply simulations of [...]
Posted in: Astrophysics
November 27th, 2008 / No Comments
Cosmic rays have long been somewhat of a mystery to scientists. These high energy/high velocity particles are thought to originate from a variety of sources: from process within the Sun for the lowest energy variety all the way up to rotating neutron stars, supernovae, and black holes for the highest energy particles. Since July 2000 [...]
Posted in: Astrophysics, High Energy
November 26th, 2008 / No Comments
If anyone has read Diamond Age, then they know of the possibilities associated with nanomachines. They will be able to cure diseases by entering your body, kill people by entering their body, automatically construct whatever is needed(perhaps more nanomachines), and many more things. But first, there is the large task of determining just how to make these things. Specifically, powering them is a challenge.
The relationship between Nanophotonics and Nanomechanics is explored in [...]
Posted in: Atomic, Molecular, and Optical
November 26th, 2008 / No Comments
A pretty interesting article about the structure of the Universe - whether it is actually homogeneous and isotropic. These assumptions were at one point held as probably true, but the more we learn, the less likely they become.
The most interesting part says that the inhomogeneity might arise from [...]
Posted in: Astrophysics
