Difference between revisions of "Hubble's Law and Scale Factors"

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(Created page with '===Short Topical Videos=== * [https://www.youtube.com/watch?v=1V9wVmO0Tfg Hubble's Law (Khan Academy)] * [http://study.com/academy/lesson/hubbles-law-hubbles-constant.html Hubble…')
 
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\begin{document}
 
\begin{document}
\section{Hubble's Law}
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\section*{ Hubble's Law (1929) }
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Hubble's Law is an empirical law stating that, on large scales, recessional
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velocity is proportional to distance from observer.
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$$\boxed{v=Hr}$$
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where $H$, the Hubble parameter, is not constant, but can
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vary slowly with time.  By convention, $H$ is often expressed as
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$H=100\cdot h{km\over s\cdot Mpc}$, where 1 parsec (pc) $\approx3\cdot10^{18}cm
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=3.26ly$, is the distance at which 1 AU appears as 1 arcsec on the sky. 
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The Hubble Space Telescope Key Project (Freedman et al. ApJ 553, 47, 2001)
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measured the present day value of Hubble Constant
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$H_0=72\pm 8{km\over s\cdot Mpc}$, giving us that the current timescale for
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the expansion of the universe is
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$H_0^{-1}\approx{h\over 10^{11}}yrs\approx 9.778h^{-1}Gyrs$.
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Revision as of 23:59, 17 January 2016

Short Topical Videos


Reference Material

Hubble’s Law (1929)

Hubble’s Law is an empirical law stating that, on large scales, recessional velocity is proportional to distance from observer.

where , the Hubble parameter, is not constant, but can vary slowly with time. By convention, is often expressed as , where 1 parsec (pc) , is the distance at which 1 AU appears as 1 arcsec on the sky. The Hubble Space Telescope Key Project (Freedman et al. ApJ 553, 47, 2001) measured the present day value of Hubble Constant , giving us that the current timescale for the expansion of the universe is .