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Re: Galactic Interface Dark Surface

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Mike Duffy wrote:

> On Wed, 10 Aug 2016 18:54:53 +0200, Thomas 'PointedEars' Lahn wrote:
>> [...] baryonic matter *does* account for only about 1 % of the total
>> mass-energy of the universe plus ca. 4 % from photons and weakly
>> interacting particles like neutrinos.  The rest is dark matter (ca. 27 %)
>> and dark energy (ca. 68 %) […]  There is *a lot* more both dark matter 
>> and dark energy than there is baryonic matter […]
> 
> Assuming the 95% total is correct for total mass-energy needed, how can
> we further categorize it into dark 'matter' (=== mass?) and dark
> 'energy'

The special and general theory of relativity show that mass and energy are 
equivalent quantities.  [E(p) = √((m c²)² + (p c)²) → E(0) = m c².
c = 1 → E = m.]

> when we have no idea of what either entails?

By their observable effects on the rest of the energy content of the 
universe.

> Worded differently, what is the difference between dark energy and dark
> matter? I always thought that the commonly used term 'dark matter' was
> just a way to express the idea of the missing mass.

Put simply:  Dark matter is gravitationally attractive on short scales 
(binding baryonic matter to make galaxies etc.); dark energy is 
gravitationally repulsive on long scales (increasing the speed of
universal expansion).

Note that the word “dark” has different meanings in each term: In “dark 
matter”, it refers primarily to the fact that this matter does not emit 
electromagnetic radiation; in “dark energy” primarily to the fact that we do 
not know why it has to be there, according to observations and calculation.

By contrast to dark matter, dark energy is not a stuff; it is the energy 
that *empty* space (*void* of observable particles) needs to have in order 
to explain the observations that the speed of the expansion of the universe 
is increasing instead of staying constant or decreasing, *and* that the 
(spacetime of the observable) universe is flat (has an average curvature 
close to zero, or IOW the sum of the inner angles of a large enough triangle 
is close to 180° everywhere in the observable universe; see also Lawrence 
Krauss’ excellent talks).

Please trim your quotes and quote the rest properly, marking *all* 
omissions.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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Thread

Galactic Interface Dark Surface Alan Folmsbee <omnilobe@gmail.com> - 2016-08-09 14:12 -0700
  Re: Galactic Interface Dark Surface Michael J. Strickland <michael06582@comcast.net> - 2016-08-09 19:45 -0400
    Re: Galactic Interface Dark Surface benj <benj@nobody.net> - 2016-08-09 20:23 -0400
    Re: Galactic Interface Dark Surface Alan Folmsbee <omnilobe@gmail.com> - 2016-08-09 17:39 -0700
    Re: Galactic Interface Dark Surface Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-10 18:54 +0200
      Arp, haltoN noTthaTguY <abu.kuanysh05@gmail.com> - 2016-08-10 11:10 -0700
        Re: Arp, haltoN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-10 20:19 +0200
        Re: Arp, haltoN Michael J. Strickland <michael06582@comcast.net> - 2016-08-10 23:27 -0400
          Re: Arp, haltoN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-11 06:27 +0200
            Re: Re: Arp, haltoN Michael J. Strickland <michael06582@comcast.net> - 2016-08-11 06:10 -0400
              Dark matter (was: Re: Arp, haltoN) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-11 18:52 +0200
                Dark matter (was: Re: Arp, haltoN) john <johnsefton288@gmail.com> - 2016-08-11 11:59 -0700
                Re: Dark matter (was: Re: Arp, haltoN) Michael J. Strickland <michael06582@comcast.net> - 2016-08-12 06:09 -0400
                Re: Dark matter Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-13 17:27 +0200
      Re: Galactic Interface Dark Surface Mike Duffy <mqduffy001@bell.net> - 2016-08-10 21:35 -0400
        Re: Galactic Interface Dark Surface Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-11 05:48 +0200
          Re: Galactic Interface Dark Surface noTthaTguY <abu.kuanysh05@gmail.com> - 2016-08-11 13:59 -0700
            Re: Galactic Interface Dark Surface Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-08-12 06:46 +0200
              a.s.c.i.i noTthaTguY <abu.kuanysh05@gmail.com> - 2016-08-12 12:35 -0700

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