A UNIVERSE WITHOUT A CENTER?

Image Credit: Eugenio Bianchi, Carlo Rovelli & Rocky Kolb.

According to the standard theories of cosmology, there is no center of the universe.
In a conventional explosion, material expand out from a central point and the instinct suggests that with the Big Bang happened something similar.
But the Big Bang was not an explosion like that at all: it was an explosion of space, not an explosion in space. The Big Bang happened everywhere in the Universe.

Current theories which are based for example on the observation of uniformity in all directions of the cosmic background radiation suggest this hypothesys.
The universe can be compared to the two-dimensional surface of an expanding balloon (this is the classic example used to explain its expansion). The whole universe would be limited to surface alone and would not include the space inside or outside of the surface of the balloon. Therefore there is no center, because on the surface of the balloon is not possible to identify a center.
In this analogy it is important to remember that, unlike the ballon, the universe is three-dimensional and not two-dimensional, that the size can be finite or infinite and that galaxies do not expand although are moving away because they are gravitationally bound.

► Read more>>
http://phys.org/news/2015-02-big.html

► Image Credit:
Eugenio Bianchi, Carlo Rovelli & Rocky Kolb.

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Astrophysics collection (March 11, 2016)

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A BINARY ORIGIN FOR A CENTRAL COMPACT OBJECT (CCO)?

Figure: False-Colour X-ray and infrared emission image from the core of the infrared shell. The RGB colours correspond to Chandra X-ray 0.2-10 keV (blue), IRAC infrared 8 μm (green), and HPACS 70 μm (red) data. The intensity scale is logarithmic for all channels. Overlaid are equal brightness levels from the MIPS 24 μm band. Note that around the CCO the infrared emission is suppressed in the 70 μm band and enhanced in the 24 μm band suggesting higher dust temperature. Credit: Doroshenko et al 2016 Central compact objects (CCOs) are thought to be young isolated neutron stars that were born during the preceding core-collapse supernova explosion.

SUPERNOVAE FROM WD-WD DIRECT COLLISIONS

Image: Supernova remnant N 63A. Credit: NASA/ESA/HEIC and The Hubble Heritage Team (STScI/AURA) Models for supernovae (SNe) related to thermonuclear explosions of white dwarfs (WDs) have been extensively studied over the last few decades, mostly focusing on single degenerate (accretion of material of a WD) and double degenerate (WD-WD merger) scenarios.

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