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The timeline in this schematic diagram extends from the Big Bang/inflation era 13.8 billion years ago to the present cosmological time. Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time.
The red line is the path of a light beam emitted by the quasar about 13 billion years ago and reaching Earth at the present day. The orange line shows the present-day distance between the quasar and Earth, about 28 billion light-years, which is a larger distance than the age of the universe multiplied by the speed of light, ct.
The thinning of matter over time reduces the ability of gravity to decelerate the expansion of the universe; in contrast, dark energy (believed to be a constant scalar field throughout the visible universe) is a constant factor tending to accelerate the expansion of the universe. The universe's expansion passed an inflection point about five or ...
1810 – François Arago observes that the speed of light of stars – measured with stellar aberration – may be independent of the relative motion of stars and the Earth; or at least, no differences are observable with a naked eye. [4] 1818 – Augustin-Jean Fresnel proposes his model of partial aether dragging to explain Arago’s finding. [5]
The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its currently understood age of 13.8 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science.
This is a timeline of the Universe from the Big Bang to the heat death scenario. The different eras of the universe are shown. The heat death will occur in around 1.7×10 106 years, if protons decay .
Since the universe has a finite age, and light travels at a finite speed, there may be events in the past whose light has not yet had time to reach earth. This places a limit or a past horizon on the most distant objects that can be observed. Conversely, because space is expanding, and more distant objects are receding ever more quickly, light ...
It represents the boundary between the observable and the unobservable regions of the universe, so its distance at the present epoch defines the size of the observable universe. Due to the expansion of the universe, it is not simply the age of the universe times the speed of light, as in the Hubble horizon, but rather the speed of light ...