wmap wiki

Halaman ini terakhir diubah pada 22 Oktober 2020, pukul 02.46. Thus, it provides a direct estimate of the Hubble parameter. Čas poslednej úpravy tejto stránky je 22:21, 26. apríl 2018. [94][95] While none of these are supported by observations, they are not ruled out. the vacuum energy. A 2011 survey, the WiggleZ galaxy survey of more than 200,000 galaxies, provided further evidence towards the existence of dark energy, although the exact physics behind it remains unknown. Modern observational data allow us to estimate the present density of the dark energy. They allow researchers to measure the expansion history of the universe by looking at the relationship between the distance to an object and its redshift, which gives how fast it is receding from us. Independently of its actual nature, dark energy would need to have a strong negative pressure (repulsive action), like radiation pressure in a metamaterial,[25] to explain the observed acceleration of the expansion of the universe. WMAP mission scores 'world's most cited' in science pubs "WMAP results were among the most-cited scientific papers in the world across all scientific disciplines [in 2011], not just in physics and astronomy. 2003 metų vasario 11 d. NASA publikavo pirmus rezultatus apie Visatos amžių ir sudėtį.
Duomenys atitinka plokščios Visatos geometriją su Ω = 1.02 +/- 0.02. If acceleration began earlier in the universe, structures such as galaxies would never have had time to form, and life, at least as we know it, would never have had a chance to exist. Supernovae are useful for cosmology because they are excellent standard candles across cosmological distances. This page was last edited on 20 October 2019, at 07:39. This implies the existence of an additional form of energy to account for the remaining 70%. In order for it not to clump and form structure like matter, the field must be very light so that it has a large Compton wavelength. No evidence of quintessence is yet available, but it has not been ruled out either. [76] A laboratory direct detection attempt failed to detect any force associated with dark energy.[46]. Wilkinson Microwave Anisotropy Probe) - Vilkinsono vardo mikrobangų anizotropijos zondas - NASA palydovas, kurio paskirtis yra išmatuoti poliarizaciją ir temperatūrą reliktinio spinduliavimo, likusio po Didžiojo sprogimo. Matter is anything whose energy density scales with the inverse cube of the scale factor, i.e., ρ ∝ a−3, while radiation is anything which scales to the inverse fourth power of the scale factor (ρ ∝ a−4). Measurements of the cosmic microwave background suggest the universe began in a hot Big Bang, from which general relativity explains its evolution and the subsequent large scale motion. Astrophysicists scramble to patch a hole in the universe, rewriting cosmic history in the process", "First Planck results: the Universe is still weird and interesting", https://einsteinpapers.press.princeton.edu/vol7-trans/47, "Astronomers Report Evidence of 'Dark Energy' Splitting the Universe", "Cosmology: Part III Mathematical Tripos, Cambridge University", "Wilkinson Microwave Anisotropy Probe (WMAP) three year results: implications for cosmology", Philosophical Transactions of the Royal Society A, "Big Bang's afterglow shows universe is 80 million years older than scientists first thought", "Planck reveals an almost perfect universe", "Dark Energy May Be Incompatible With String Theory", "Is Einstein's Greatest Work All Wrong – Because He Didn't Go Far Enough? The large difference between these two supports a smooth component of dark energy making up the difference. Misi WMAP adalah misi ruang angkasa COBE yang berhasil dan pesawat ruang angkasa kedua kelas medium (MIDEX) dari program Explorer. [82][83][84], Astrophysicist Ethan Siegel states that, while such alternatives gain a lot of mainstream press coverage, almost all professional astrophysicists are confident that dark energy exists, and that none of the competing theories successfully explain observations to the same level of precision as standard dark energy.[85]. Specifically, a change in volume dV requires work done equal to a change of energy −P dV, where P is the pressure.

Pesawat ruang angkasa WMAP diluncurkan pada 30 Juni, 2001 at 19:46:46 GDT, dari Florida. The theoretical need for a type of additional energy that is not matter or dark matter to form the. This is related to the Casimir effect, in which there is a small suction into regions where virtual particles are geometrically inhibited from forming (e.g. But the amount of energy in a container full of vacuum actually increases when the volume increases, because the energy is equal to ρV, where ρ is the energy density of the cosmological constant. This class of theories attempts to come up with an all-encompassing theory of both dark matter and dark energy as a single phenomenon that modifies the laws of gravity at various scales. The cosmological constant was first proposed by Einstein as a mechanism to obtain a solution of the gravitational field equation that would lead to a static universe, effectively using dark energy to balance gravity.
Forskarlaget bakom WMAP har släppt data tre gånger, de senaste kom i januari 2010 och var baserade på sju års observationer. (2017). unknown property in cosmology that causes the expansion of the universe to accelerate. [12] This would need to be almost, but not exactly, cancelled by an equally large term of the opposite sign. Work done in 2013 based on the Planck spacecraft observations of the CMB gave a more accurate estimate of 68.3% dark energy, 26.8% dark matter, and 4.9% ordinary matter.[35].

In these models, the quintessence field has a density which closely tracks (but is less than) the radiation density until matter-radiation equality, which triggers quintessence to start behaving as dark energy, eventually dominating the universe. If considered as a "source term" in the field equation, it can be viewed as equivalent to the mass of empty space (which conceptually could be either positive or negative), or "vacuum energy". The Wilkinson Microwave Anisotropy Probe (WMAP) is a NASA Explorer mission that launched June 2001 to make fundamental measurements of cosmology -- the study of the properties of our universe as a whole. V rokoch 2002 a 2004 bola misia predĺžená až na celkovú dobu deviatich rokov (oproti pôvodne plánovaným dvom rokom), s ukončením misie sa počíta v septembri 2010.[1]. [80][81] The measurement of the speed of gravity in the first gravitational wave measured by non-gravitational means (GW170817) ruled out many modified gravity theories as explanations to dark energy. WMAP has been stunningly successful, producing our new Standard Model of Cosmology. Most quantum field theories predict vacuum fluctuations that would give the vacuum this sort of energy. Using baryon acoustic oscillations, it is possible to investigate the effect of dark energy in the history of the Universe, and constrain parameters of the equation of state of dark energy. Norint efektyviai atmesti mūsų Galaktikos šaltinius, WMAP naudojo penkias skirtingas dažnio juostas tarp 22 ir 90  GHz. For example, if we are located in an emptier-than-average region of space, the observed cosmic expansion rate could be mistaken for a variation in time, or acceleration. An attempt to directly observe dark energy in a laboratory failed to detect a new force.[46].

Seife, Charles, BREAKTHROUGH OF THE YEAR: Šis puslapis paskutinį kartą keistas 7 kovo 2015 19:41. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. Therefore, it is conceivable that a modification to general relativity also eliminates the need for dark energy. WMAP var en efterföljare till COBE-satelliten och hade liksom COBE som uppgift att mäta och kartlägga de mycket små fluktuationerna i den kosmiska bakgrundsstrålningen för att hjälpa till att testa kosmologiska teorier om universum. [37] This provides a confirmation to cosmic acceleration independent of supernovae. Dark energy's status as a hypothetical force with unknown properties makes it a very active target of research. Work done in 2013 based on the Planck spacecraft observations of the CMB gave a more accurate estimate of 68.3% dark energy, 26.8% dark matter, and 4.9% ordinary matter. [17][18], The mechanism was an example of fine-tuning, and it was later realized that Einstein's static universe would not be stable: local inhomogeneities would ultimately lead to either the runaway expansion or contraction of the universe. The reason dark energy can have such a profound effect on the universe, making up 68% of universal density in spite of being so dilute, is that it uniformly fills otherwise empty space. During the 1980s, most cosmological research focused on models with critical density in matter only, usually 95% cold dark matter (CDM) and 5% ordinary matter (baryons). [4][5][6][7] The density of dark energy is very low (~ 7 × 10−30 g/cm3), much less than the density of ordinary matter or dark matter within galaxies.


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