Re: String langscapes and vacuum decay


Russell Wallace wrote:
> Leonard Susskind writes:
>
> " Is it possible to test the landscape idea through observation?

Observation is the only way to physically test *any* idea. We call this
concept 'empiricism.'

> One idea is to look for signs that space is negatively curved,
> meaning the
> geometry of space-time is saddle-shaped as opposed to flat or like
> the surface of
> a sphere.

In a large universe the apparent population of galaxies in a given
angular sector of space will depend on their distance and the overall
curvature of the space.

In a homogeneous 'flat' universe (no curvature) the number of galaxies
in such a sector will increase in direct proprtion to the square of the
distance from the observer. This is a result of the so-called 'inverse
square' law.

In a homogeneous 'spherical' universe (positive curvature) the number
of galaxies is finite, and the apparent number of galaxies per angular
sector at any given distance will not increase as fast as the square of
the distance.

In a homogeneous 'hyperbolic' universe (negativecurvature) the number
of galaxies is infinite, and the apparent number of galaxies per
angular sector at any given distance will increase faster than the
square of the distance. In a sufficiently large universe this would
manifest as an incredibly bright night sky (Google "Olber's Paradox").

Tom Davidson
Richmond, VA

.

Relevant Pages

  • Re: Expansion and balloon analogy
    ... I.e., the distance between ... other of the galaxies observed. ... > permeated with a dense filling of dust particles. ... does not exist in the real universe, ...
    (sci.physics.relativity)
  • Re: The Cosmological Principle
    ... >> galaxies out to a distance of almost 2 billion light years. ... >> how the matter in the universe was distributed. ... And since these stars are liable to no sensible parallax from ... their immense distance, to produce any sensible effect in our system. ...
    (sci.astro.amateur)
  • REDSHIFT IN A STABLE UNIVERSE
    ... Old massives galaxies, giant strings of galaxies, or iron-rich quasars ... the universe should appear very young at such distances. ... when viewed on sufficiently large distance scales, ...
    (sci.physics.research)
  • Re: The Current Universe Being Observed Is No Longer There
    ... cow standing in a field that I see through my window took some time to reach ... universe at all and "we" are down to exactly one entity. ... "Let's go back to Hubble's observation that distant galaxies appear to ... This distance is called the Hubble ...
    (talk.origins)
  • The Gravitational Instability Theory on the Formation of the Universe
    ... Science knows the formation of matter in our universe was caused by ... RUFUS'S GALAXY WEB PAGE ... Basic Operation of Galaxies ...
    (sci.space.policy)