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The history of the universe after inflation but before a time of about 1 second is largely unknown. [22] However, the universe is known to have been dominated by ultrarelativistic Standard Model particles, conventionally called radiation, by the time of neutrino decoupling at about 1 second. [23]
This future history and the timeline below assume the continued expansion of the universe. If space in the universe begins to contract, subsequent events in the timeline may not occur because the Big Crunch, the collapse of the universe into a hot, dense state similar to that after the Big Bang, will prevail. [14] [15]
Thus, an accelerating universe took a longer time to expand from 2/3 to 1 times its present size, compared to a non-accelerating universe with constant ˙ and the same present-day value of the Hubble constant. This results in a larger light-travel time, larger distance and fainter supernovae, which corresponds to the actual observations.
Observations made by Edwin Hubble during the 1930s–1950s found that galaxies appeared to be moving away from each other, leading to the currently accepted Big Bang theory. This suggests that the universe began very dense about 13.787 billion years ago, and it has expanded and (on average) become less dense ever since. [1]
The chances of asteroid 2024 YR4 colliding with Earth in 2032 hit a record high. ... Explore the universe with news on fascinating ... NASA calculated that the space rock had a 3.1% chance of ...
By the 1940s, magnetic north had moved northwest from its 1831 position by about 250 miles (400 kilometers). In 1948, it reached Prince Wales Island, and by 2000 it had departed Canadian shores.
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The concept of an expanding universe was scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.
This is because the travel time between any two points for a non-relativistic moving particle will just be the proper distance (that is, the comoving distance measured using the scale factor of the universe at the time of the trip rather than the scale factor "now") between those points divided by the velocity of the particle.