| Science/Technology
|
[
Science/Technology ] [ Main Menu ] |
|
|
|
4854 |
|
|
Date: March 19, 2014 at 05:57:06
From: Akira, [DNS_Address]
Subject: accelerating expansion of space..corollary for time? |
|
|
I'm wondering if space is expanding at an ever accelerated rate, is there a corollary for time or our perception of time? Since the expansion of space theoretically can/does exceed the speed of light, does this change the relationship of space and time?
Does anyone know of any scientific data or investigation?
Time is on my mind.
|
|
|
|
|
Responses:
[4864] |
|
4864 |
|
|
Date: March 28, 2014 at 12:07:01
From: marc / berkeley, [DNS_Address]
Subject: Re: accelerating expansion of space..corollary for time? |
URL: Time/Expansion of Universe? Read more: http://www.physicsforums.com |
|
Hubble's law is the name for the observation in
physical cosmology that: (1) objects observed in deep
space (extragalactic space, ~10 megaparsecs or more)
are found to have a Doppler shift interpretable as
relative velocity away from the Earth; and (2) that
this Doppler-shift-measured velocity, of various
galaxies receding from the Earth, is approximately
proportional to their distance from the Earth for
galaxies up to a few hundred megaparsecs away. This is
normally interpreted as a direct, physical observation
of the expansion of the spatial volume of the
observable universe.
The motion of astronomical objects due solely to this
expansion is known as the Hubble flow. Hubble's law is
considered the first observational basis for the
expanding space paradigm and today serves as one of the
pieces of evidence most often cited in support of the
Big Bang model.
Although widely attributed to Edwin Hubble, the law was
first derived from the General Relativity equations by
Georges Lemaître in a 1927 article where he proposed
that the Universe is expanding and suggested an
estimated value of the rate of expansion, now called
the Hubble constant. Two years later Edwin Hubble
confirmed the existence of that law and determined a
more accurate value for the constant that now bears his
name. The recession velocity of the objects was
inferred from their redshifts, many measured earlier by
Vesto Slipher (1917) and related to velocity by him.
The law is often expressed by the equation v = HoD,
with Ho the constant of proportionality (the Hubble
constant) between the "proper distance" D to a galaxy
(which can change over time, unlike the comoving
distance) and its velocity v (i.e. the derivative of
proper distance with respect to cosmological time
coordinate; see Uses of the proper distance for some
discussion of the subtleties of this definition of
'velocity'). The SI unit of H0 is s−1 but it is most
frequently quoted in (km/s)/Mpc, thus giving the speed
in km/s of a galaxy 1 megaparsec (3.09×1019 km) away.
The reciprocal of Ho is the Hubble time.
|
|
|
|
|
Responses:
None |
|
[
Science/Technology ] [ Main Menu ] |