Search results
Results From The WOW.Com Content Network
Hubble's law can be easily depicted in a "Hubble diagram" in which the velocity (assumed approximately proportional to the redshift) of an object is plotted with respect to its distance from the observer. [30] A straight line of positive slope on this diagram is the visual depiction of Hubble's law.
Even light itself does not have a "velocity" of c in this sense; the total velocity of any object can be expressed as the sum = + where is the recession velocity due to the expansion of the universe (the velocity given by Hubble's law) and is the "peculiar velocity" measured by local observers (with = ˙ () and = ˙ (), the dots indicating a ...
For example, 7 × 10 13 h −1 M ☉ = 10 14 h −1 0.70 M ☉. Our best measurement, as of 2013, for the Hubble parameter is h = 0.6780 ± 0.0077 from the Planck mission. In early 2011 it was 0.704 +0.013 −0.014 from WMAP 7-year data. [1] See Hubble's law#Determining the Hubble constant for the most recent value of H 0.
The observational result of Hubble's law, the proportional relationship between distance and the speed with which a galaxy is moving away from us, usually referred to as redshift, is a product of the cosmic distance ladder. Edwin Hubble observed that fainter galaxies are more redshifted. Finding the value of the Hubble constant was the result ...
Using the Planck units, and the value evaluated in 2025 for the Hubble constant H 0 = 76.5 ± 2.2 (km/s)/Mpc = (2.48 ± 0.07) × 10 −18 s −1, [18] Λ has the value of = = = where is the Planck length. A positive vacuum energy density resulting from a cosmological constant implies a negative pressure, and vice versa.
The Hubble parameter can change over time if other parts of the equation are time dependent (in particular the mass density, the vacuum energy, or the spatial curvature). Evaluating the Hubble parameter at the present time yields Hubble's constant which is the proportionality constant of Hubble's law .
Hubble's law predicts that objects farther than the Hubble horizon are receding faster than light. This outcome is not in violation of special relativity. Since special relativity treats flat spacetimes, it is only valid over small distances within the context of the curved spacetime of the universe.
where is the Hubble constant, is the proper distance, is the object's recessional velocity, and is the object's peculiar velocity. The recessional velocity of a galaxy can be calculated from the redshift observed in its emitted spectrum. One application of Hubble's law is to estimate distances to galaxies based on measurements of their ...