Tag: NASA researches
Assuming the standard model is true, our universe’s end will likely all come down to one of three theories, each of which depends upon three things: the shape of the universe, how much dark energy is contained within it, and how the densities of dark energy will respond to the expansion of the universe.
There are believed to be three possible shapes of the universe: an open universe, a flat universe, and a closed plane of space-time.
In an open universe (think of a gigantic, saddle-shaped object), the universe is likely to experience the Big Freeze. In this scenario, the universe will continue to expand until matter has stretched incredibly thin, the stars have all burnt out, galaxies have ceased creating new stars to replace them, and all mass as we know it has ceased to exist. Everything will become dark and cold. The universe won’t so much as end as it will simply fizzle out, settling into a silent and lonely slumber at absolute zero.
Another possibility for universal armageddon is the Big Rip. Not as dependent on the shape of the universe as much as the amount of dark energy contained within it, this model implies that the acceleration of the universe will continue to increase without slowing, and the dark energy will become so strong that it will overwhelm the other elemental forces. Galaxies, suns, and planets alike will begin tearing themselves apart, all ending in a gravitational singularity — a place in which the standard rules of physics and relativity no longer apply.
Somewhat less unsettling is the theory of the Big Crunch, in which the universe will continue to expand until matter begins to slow the rate of expansion. Once slowed enough, the expansion will eventually come to a halt and begin to retract. Everything — planets, suns, galaxies, black holes, even the indestructible iPad 7000 — will all come crashing back together, culminating in a Big Crunch: essentially the opposite of the Big Bang that kicked our universe off in the first place. The bright side here is that the crunch is thought to be succeeded by yet another Big Bang and the creation of a whole new universe. Unfortunately, of the three, the Big Crunch is currently the least favored hypothesis within the physics community — meaning our dreams of an endlessly cycling universe of birth, destruction, and rebirth may end up being relegated to the realm of science fiction.
Dark matter continues to confound astronomers, as NASA’s Chandra X-ray Observatory demonstrated with the detection of an extensive envelope of dark matter around an isolated elliptical galaxy. This discovery conflicts with optical data that suggest a dearth of dark matter around similar galaxies, and raises questions about how galaxies acquire and keep such dark matter halos.
Dark matter is a mysterious kind of glue that holds not only the mysterious together, but is theoretically responsible for their creation. It was originally suggested in 1933 to explain discrepancies math by calculating the mass of galaxies, essentially, more material is needed to keep the galaxies together, we can see. Since then, we have not learned a whole hell of a lot more about dark matter.
In fact, we seem to know more about this itisn’t than it is. We know there is no antimatter. We also know that there is no dark clouds of normal matter. Many physicists believe that it represents about 83% of matter in the universe – even if we still have to prove that it exists!
The tricky thing with the dark matter is that we can not be detected directly, it is invisible. Dark matter is revealed by its severity, so we have, instead of measuring it through its interaction with normal matter. Currently, there are two contradictory experiments conducted in an attempt to confirm the existence of dark matter.
The Cryogenic Dark Matter Search (CDMS) detector Sudan mine in Minnesota is the search for weakly interacting massive particles, or WIMPs, whose discovery could resolve the problem of dark matter. Although the dark matter should be everywhere, it is estimated that some WIMPs can pass through the galaxy without interacting with normal matter, making it very difficult to discover. Although scientists have not yet detected WIMPs directly, they found significant evidence that they exist.
In direct conflict with these results, the XENON100 experience in Gran Sasso Laboratory in Italy has so far yielded negative results with respect to the WIMP. This does not mean that WIMPs exist, but simply that they are harder to detect than scientists had previously assumed.
The Milky Way Galaxy, commonly referred to as just the Milky Way, or sometimes simply as the Galaxy,[a] is the home galaxy of the Solar System, and of Earth. It is agreed that the Milky Way is a spiral galaxy, with observations suggesting that it is a barred spiral galaxy.
It contains 200-400 billion stars and is estimated to have at least 50 billion planets, 500 million of which could be located in the habitable zone of their parent star. New data suggests there may be up to twice as many free-floating planets in the Milky Way as there are stars. The Milky Way is part of the Local Group of galaxies and is one of around 200 billion galaxies in the observable universe.
The Solar System is located in the Milky Way galaxy around two thirds of the way out from the center, on the inner edge of the Orion–Cygnus Arm. The Sun orbits around the center of the galaxy in a galactic year—once every 225-250 million Earth years.
The “Milky Way” is a translation of the Latin Via Lactea, in turn translated from the Greek Γαλαξίας (Galaxias), referring to the pale band of light formed by stars in the galactic plane as seen from Earth.
All the stars that the eye can distinguish in the night sky are part of the Milky Way galaxy, but aside from these relatively nearby stars, the galaxy appears as a hazy band of white light arching around the entire celestial sphere. The light originates from stars and other material that lie within the galactic plane. Dark regions within the band, such as the Great Rift and the Coalsack, correspond to areas where light from distant stars is blocked by dark nebulae.
The Milky Way has a relatively low surface brightness due to the interstellar medium that fills the galactic disk, which prevents us from seeing the bright galactic center. It is thus difficult to see from any urban or suburban location suffering from light pollution. A total integrated magnitude of the whole Milky Way stretching across the night sky has been estimated at −5.0.
The center of the galaxy lies in the direction of Sagittarius, and it is here that the Milky Way looks brightest. From Sagittarius, the hazy band of white light appears to pass westward through the constellations of Scorpius, Ara, Norma, Triangulum Australe, Circinus, Centaurus, Musca, Crux, Carina, Vela, Puppis, Canis Major, Monoceros, Orion and Gemini, Taurus, Auriga, Perseus, Andromeda, Cassiopeia, Cepheus and Lacerta, Cygnus, Vulpecula, Sagitta, Aquila, Ophiuchus, Scutum, and back to Sagittarius. The fact that the band divides the night sky into two roughly equal hemispheres indicates that the Solar System lies close to the galactic plane.
The galactic plane is inclined by about 60 degrees to the ecliptic (the plane of the Earth’s orbit). Relative to the celestial equator, it passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth’s equatorial plane and the plane of the ecliptic relative to the galactic plane. The north galactic pole is situated at right ascension 12h 49m, declination +27.4° (B1950) near beta Comae Berenices, and the south galactic pole is near alpha Sculptoris.