sci.physics.relativity
  Home FAQ Contact Sign in
sci.physics.relativity only
 
Advanced search
December 2007
motuwethfrsasuw
     12 48
3456789 49
10111213141516 50
17181920212223 51
24252627282930 52
31       1
2007
 Jan   Feb   Mar   Apr 
 May   Jun   Jul   Aug 
 Sep   Oct   Nov   Dec 
2008 2007 2006  
total
sci.physics.relativity Profile…
RELATED GROUPS

POPULAR GROUPS

more...

 Up
  Re: Time can not be curved without also curving space.         


Author: Koobee Wublee
Date: Dec 16, 2007 23:42

On Dec 16, 8:23 am, Tom Roberts wrote:
> Jeff☠Relf wrote:
>> In General Relativity,
>> time can not be curved without also curving space;
>> otherwise, c would not be a universal constant.
>
> This is not true. In GR, c is a universal constant that is the speed of
> light MEASURED LOCALLY. In any manifold with any metric one can always
> find Riemann normal coordinates at any point, which in GR are the same
> as local Minkowski coordinates in which the LOCAL speed of light is
> isotropically c.

This is totally untrue.

Given the following equation describing the curvature in spacetime,

ds^2 = g_ij dq^i dq^j

The speed of light, c, is how whoever the observer is using the
coordinate system of dq would have observed the speed of light
himself. It is not a local parameter as you have described it.
Show full article (2.71Kb)
1 Comment
  Re: SYMPTOMS OF DEAD SCIENCE         


Author: Pentcho Valev
Date: Dec 16, 2007 23:23

The most "critical" Einsteinian:

http://www.nyas.org/publications/UpdateUnbound.asp?UpdateID=41
Lee Smolin: "Then, about 30 years ago, something changed. The last
time there was a definitive advance in our knowledge of fundamental
physics was the construction ofthe theory we call the standard model
of particle physics in 1973. The last time a fundamental theory was
proposed that has since gotten any support from experiment was a
theory about the very early universe called inflation, which was
proposed in 1981......I should emphasize that this crisis involves
only fundamental physics....."

The hypocrisy of the most "critical" Einsteinian:
Show full article (1.98Kb)
no comments
  Re: GR1916, available online.         


Author: John Park
Date: Dec 16, 2007 22:02

bz (bz+spr@ch100-5.chem.lsu.edu) writes:
>
[...]
> I will say one thing about tensor's and the notation systems used for
them:
> I wish that the subscripts and superscripts had been placed on the left,
> rather than the right.
>
> Don't you agree?

Funn
--that's a thought that periodically occurs to me, and it happened to
cross my mind today. I even checked the (A,Z) format of isotope symbols
as a comparison. (And then I forgot about it again.) I suppose it's too
late to change now, but I do wonder why no one thought of it way back when.

--John Park
no comments
  Re: Space expansion and moving galaxies; The age of the universe.         


Author: Pepe le Pew
Date: Dec 16, 2007 15:55

BURT wrote:
> On Dec 16, 10:14 am, Pepe le Pew biteme.com> wrote:
>> BURT wrote:
>>> The galaxies are not moving through a preexisting space away from one
>>> another. Instead space is expanding. The red shift from motion and
>>> Space expansion are equivalent. We can calculate galactic distances
>>> because of this equivalence. Universal Expansion is Distance growing.
>>> The curved space-time continuum is expanding. This is the growing of
>>> the hypersphere and surface; or a closed universe; finite yet
>>> unbounded with space curving back on itself in the 4th dimension.
>>> Atronomers calculate the age of the universe from the most distant
>>> objects. They are said to lay 13 billion light years away. So because
>>> they believe the past lies in the distance they calculate the age of
>>> the universe to be 13 billion years.
>>> They left out the time it took for these galaxies to expand out to
>>> this distance. They left out universal expansion that brings them out
>>> to distance.
>>> I calculate the age of the universe to be a combination of the time it
>>> took for the universe to expand to what we see and add the time it
>>> took for light to come back to us. The universe expanded for 22 ...
Show full article (3.15Kb)
no comments
  Re: Hi to ALL. I just join this group.         


Author: Pmb
Date: Dec 16, 2007 15:52

gmail.com> wrote in message
news:72204906-b8cd-47c0-ae0e-ebeed5cac3a1@l32g2000hse.googlegroups.com...

Hi.

Since you seem to be using tis forum for advertising I'm going to have to
plonk you (i.e. place you in my kill file). Expect the same from some others
who post here.

Pete
no comments
  Re: Relativistic electrodynamics without photons         


Author: Bill Hobba
Date: Dec 16, 2007 15:31

"Juan R. Gonz
no comments
  Re: Falling Toward Light         


Author: Pepe le Pew
Date: Dec 16, 2007 15:09

Paul Hovnanian P.E. wrote:
> BURT wrote:
>> Moving through space or falling toward light as it comes out of
>> gravity blue shifts it. GPS.
>> Falling through space along the direction of motion of a light beam
>> will redshift it.
>>
>> GPS.
>> MItch Raemsch -- Falling Toward Light --
>
> So, how do you explain this: Accelerating away from a light source
> causes it to alternate between red and blue in the rear view mirror.
>
> Happens in my Porsche all the time.
>
Paul,

Switch to a superbike. They blend into the cosmic dust and
fly under the radar of passing galaxies.
Show full article (0.61Kb)
no comments
  Re: Space expansion and moving galaxies; The age of the universe.         


Author: s.desear
Date: Dec 16, 2007 14:53

On Dec 14, 8:39 pm, BURT yahoo.com> wrote:
> The galaxies are not moving through a preexisting space away from one
> another. Instead space is expanding. The red shift from motion and
> Space expansion are equivalent. We can calculate galactic distances
> because of this equivalence. Universal Expansion is Distance growing.
>
> The curved space-time continuum is expanding. This is the growing of
> the hypersphere and surface; or a closed universe; finite yet
> unbounded with space curving back on itself in the 4th dimension.
>
> Atronomers calculate the age of the universe from the most distant
> objects. They are said to lay 13 billion light years away. So because
> they believe the past lies in the distance they calculate the age of
> the universe to be 13 billion years.
> They left out the time it took for these galaxies to expand out to
> this distance. They left out universal expansion that brings them out
> to distance.
> I calculate the age of the universe to be a combination of the time it
> took for the universe to expand to what we see and add the time it
> took for light to come back to us. The universe expanded for 22 ...
Show full article (2.00Kb)
no comments
  "Sakharov's induced gravity: a modern perspective"         


Author: Sue...
Date: Dec 16, 2007 14:44

Abstract
Sakharov's 1967 notion of "induced gravity" is currently
enjoying a significant resurgence. The basic idea, originally
presented in a very brief 3-page paper with a total of 4 formulas,
is that gravity is not "fundamental" in the sense of particle
physics. Instead it was argued that gravity (general relativity)
emerges from quantum field theory in roughly the same
sense that hydrodynamics or continuum elasticity theory
emerges from molecular physics. In this article I will translate
the key ideas into modern language, and explain the various
versions of Sakharov's idea currently on the market. >>
--Matt Visser
http://arxiv.org/abs/gr-qc/0204062

Related:
http://arxiv.org/abs/physics/0107015 Kouropoulos
http://www.esa.int/SPECIALS/GSP/SEM0L6OVGJE_0.html Tajmar

Sue...
no comments
  Re: Fallacious Notion of Spacetime Continuum in Relativity         


Author: GSS
Date: Dec 16, 2007 06:52

JanPB wrote:
> On Dec 13, 6:53 am, GSS yahoo.com> wrote:
[......]
>> How can spacetime "dragging"_be_physical in any sense if the
>> "spacetime" itself is not a physical entity???
>
> In the sense I wrote: the spinning object does affect space and time
> measurements in a way that's consistent with certain pop-sci
> presentations, e.g. satellites of the object begin to orbit it in the
> direction of the spin. This is popularly presented as "the spinning
> object drags space around it". Whether this popular presentation is in
> fact based on something strict is not known at this point as GR itself
> is silent on the issue. Perhaps a more general theory will feature
> some "stuff" that does get "dragged". We don't know yet.

It is well known that the 'field influence' of a charged particle
spreads out in its radial direction at the speed of light. If that
charged particle starts spinning, then its radial 'field lines' will...
Show full article (12.86Kb)
42 Comments
1 2 3 4 5