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According to the position of the submillimeter galaxies in the H-ATLAS map data, investigations can
be made to identify their nature in order to study gas, dust and stars formation in far galaxies. These
properties are obtained using ground instruments.
For the present study, one fundamental question is why are the observations done in infrared and sub MM wavelengths
Section 2.2. Redshift Page 13
submillimeter wavelengths regime? One way to answer this is not only to consider the fact that galaxies
are too distant, but it becomes easier for scientists to learn about the properties and how objects are
formed in the universe. Some galaxies may contain a lot of gas and dust which obscure stellar light,
making the optical and near-infrared techniques dicult for observations. In addition, the incoming light
rays may or not be absorbed, according to the atmosphere level. We mean in the case of ambient and
low levels where the water vapour content is more important, that the incoming rays are absorbed at
submillimeter wavelengths: this complicates observations. In the case of a high altitude, the content of
water vapour is considerably reduced, which makes the space more transparent, facilitating observations.
That otherwise explains why observations are made in space rather than on Earth.
One of the important features of the universe around us is that, on sufficiently large scales, it looks pretty much the same in every direction — “isotropy,” in cosmology lingo....
A tiny effect could be lurking there, and be hard to see; or we could see a hint of it, and it would be hard to be sure it wasn’t just a statistical fluke.
In fact, at least three such instances of apparent large-scale anisotropies have been claimed.
Rethinking equilibrium: In nature, large energy fluctuations may rile even 'relaxed' systems
The research appeared online Oct. 21 in Physical Review E.
In their study, the scientists used computer simulations to model the behavior of a closed, granular system comprising a chain of equal-sized spheres that touch one another and are sandwiched between two walls. Energy travels through this system as solitary waves, also known as non-dispersive energy bundles.
When the system was disturbed by multiple energy perturbations -- imagine someone tapping on each of the walls -- the energy spread unevenly through the system.
Distinct hot and cold spots with an energy much higher and lower than the average energy per sphere persisted over short periods of time, and some regions remained cold over extended times. This held true even in simulations that lasted for several days, demonstrating that the system's eventual state was something very different from what is traditionally thought of as equilibrium.
Like many systems in nature, the system the scientists simulated is subject to strong, nonlinear forces, which vary sharply as a system evolves.
Nature's laws may vary across the Universe
One of the most cherished principles in science - the constancy of physics - may not be true, according to research carried out at the University of New South Wales (UNSW), Swinburne University of Technology and the University of Cambridge.
The study found that one of the four known fundamental forces, electromagnetism - measured by the so-called fine-structure constant and denoted by the symbol ‘alpha' - seems to vary across the Universe.