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According to the theory of cosmic inflation initially introduced by Alan Guth and D. Kazanas, [23] if it is assumed that inflation began about 10 −37 seconds after the Big Bang and that the pre-inflation size of the universe was approximately equal to the speed of light times its age, that would suggest that at present the entire universe's ...
The astronomical unit is typically used for stellar system scale distances, such as the size of a protostellar disk or the heliocentric distance of an asteroid, whereas other units are used for other distances in astronomy. The astronomical unit is too small to be convenient for interstellar distances, where the parsec and light-year are widely ...
Because humans cannot observe space beyond the edge of the observable universe, it is unknown whether the size of the universe in its totality is finite or infinite. [3] [56] [57] An estimate from 2011 suggests that if the cosmological principle holds, the whole universe must be more than 250 times larger than a Hubble sphere. [58]
This mass-radius log plot of all the universe demonstrates it visually In particle physics and physical cosmology , the Planck scale is an energy scale around 1.22 × 10 28 eV (the Planck energy, corresponding to the energy equivalent of the Planck mass, 2.176 45 × 10 −8 kg ) at which quantum effects of gravity become significant.
Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to another quantity that is ...
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 ...
The scale factor is dimensionless, with counted from the birth of the universe and set to the present age of the universe: 13.799 ± 0.021 Gyr [4] giving the current value of as () or . The evolution of the scale factor is a dynamical question, determined by the equations of general relativity , which are presented in the case of a locally ...
"Late universe" measurements using calibrated distance ladder techniques have converged on a value of approximately 73 (km/s)/Mpc. Since 2000, "early universe" techniques based on measurements of the cosmic microwave background have become available, and these agree on a value near 67.7 (km/s)/Mpc. [61] (This accounts for the change in the ...