Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: closed universe, flat space?
Replies: 48   Last Post: May 5, 2013 2:45 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
dan.ms.chaos@gmail.com

Posts: 409
Registered: 3/1/08
Re: closed universe, flat space?
Posted: Apr 25, 2013 7:34 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply


> Let?s look at spacetime.  According to GR, it is the curvature of
> spacetime that causes gravity.  So, spacetime is curved around a
> gravitating mass.  In free space, the Einstein tensor vanishes which
> means the Ricci tensor also vanishes which mean the Riemann tensor
> also vanishes.  So, you have vanished Riemann tensor in curved
> spacetime.  That means the curvature tensors really do not address the
> curvature thing.  The field equations are merely differential
> equations that allow you solve the local geometry and nothing more.
> <shrug>


http://en.wikipedia.org/wiki/Ricci-flat_manifold
The Ricci tensor vanishing does not imply the Riemann tensor does .

Also ,don't confuse space with space-time . Space is only a 'slice' of
space-time . In itself it can be flat, while still being in a curved
space-time . The metric of space is three-dimensional , and embedded
in the four dimensional metric of space-time. Even factoring out the
gravitational effects (which predominantly affect the time-time
component of the metric tensor, not it's space components ) ,we still
have to consider the expansion of the universe .

http://en.wikipedia.org/wiki/Metric_expansion_of_space

Space can be predominantly flat (provided it's free from strong
gravitational effects) , while still being embedded in a curved space-
time .

> Write down the metric for n-sphere please.  <shrug>

If the earth were perfectly round , you would return to your point of
origin when going around it . Generalize . Or better yet, use Google
to figure out the metric .

> At least, you admit your own version of cosmology is purely
> speculation.  The so-called experts believe in their speculated
> ?reality? more whole heartedly.


First, don't underestimate the value of rational speculation .I
speculate that the sun will rise tomorrow .
All science has origin in rational speculation.
Second, the most commonly accepted model of the universe is flat (in
space) and infinite.Observations confirm
the universe 'flat with only a 0.4% margin of error' .
http://en.wikipedia.org/wiki/Shape_of_the_Universe#cite_note-2

><shrug>
I find it much easier to read your post with this image in mind
http://www.bittersweetcandybowl.com/candybooru/_images/1b9e551d747b18f28b1ad49bd2835f22/3906%20-%20Jasmine%20Marshmallow_%28Artist%29%20excellent%20pony.png

If you post had a point to make, I don't see it. <shrug>




Date Subject Author
4/23/13
Read closed universe, flat space?
Rich Delaney
4/23/13
Read Re: closed universe, flat space?
Poutnik
4/24/13
Read Re: closed universe, flat space?
Shmuel (Seymour J.) Metz
4/29/13
Read Re: closed universe, flat space?
Rich Delaney
4/23/13
Read Re: closed universe, flat space?
kenseto
4/24/13
Read Re: closed universe, flat space?
JT
4/24/13
Read Re: closed universe, flat space?
herbert glazier
4/24/13
Read Re: closed universe, flat space?
Double-A
4/23/13
Read Re: closed universe, flat space?
Nicolas Bonneel
4/29/13
Read Re: closed universe, flat space?
Rich Delaney
4/29/13
Read Re: closed universe, flat space?
Mike Terry
4/23/13
Read Re: closed universe, flat space?
xxein
4/23/13
Read Re: closed universe, flat space?
Brian Q. Hutchings
4/23/13
Read Re: closed universe, flat space?
Butch Malahide
4/23/13
Read Re: closed universe, flat space?
Newberry
4/24/13
Read Re: closed universe, flat space?
Koobee Wublee
4/24/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
4/24/13
Read Re: closed universe, flat space?
Koobee Wublee
4/24/13
Read space is locally curved, as has been measured
Brian Q. Hutchings
4/25/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
4/25/13
Read Re: closed universe, flat space?
herbert glazier
4/25/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
4/25/13
Read Re: closed universe, flat space?
bradguth@gmail.com
4/27/13
Read Re: closed universe, flat space?
Brian Q. Hutchings
5/4/13
Read Re: closed universe, flat space?
bradguth@gmail.com
5/5/13
Read Re: closed universe, flat space?
Brian Q. Hutchings
4/25/13
Read Re: closed universe, flat space?
Koobee Wublee
4/25/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
4/25/13
Read Re: closed universe, flat space?
Koobee Wublee
4/25/13
Read closed universe, flat space, ignore Minkowski's worse nD geometry;
thank you
Brian Q. Hutchings
4/26/13
Read Re: closed universe, flat space, ignore Minkowski's worse nD
geometry; thank you
Brian Q. Hutchings
4/27/13
Read curved space and/or curved time (time is the "real, scalar" part of
vector mechanics -- like a God-am clock
Brian Q. Hutchings
4/27/13
Read Re: curved space and/or curved time (time is the "real, scalar" part
of vector mechanics -- like a God-am clock
Brian Q. Hutchings
4/27/13
Read Re: closed universe, flat space?
Tom Roberts
4/27/13
Read Re: closed universe, flat space?
Koobee Wublee
4/27/13
Read Re: closed universe, flat space?
Brian Q. Hutchings
4/29/13
Read Re: closed universe, flat space?
Rich Delaney
4/29/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
4/29/13
Read Re: closed universe, flat space?
Koobee Wublee
4/30/13
Read Kepler uncovered the curvature via his three orbital constraints
(reciprocal of diameter)
Brian Q. Hutchings
4/30/13
Read Minkowski was an otherwise-great geometer!
Brian Q. Hutchings
5/1/13
Read Minkowski, Minkowski, Minkowski -- say it, againsville
Brian Q. Hutchings
5/1/13
Read Kepler's cosmological curvature thingies
Brian Q. Hutchings
5/3/13
Read Re: closed universe, flat space?
Rich Delaney
5/4/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
5/4/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
5/4/13
Read Re: closed universe, flat space?
dan.ms.chaos@gmail.com
5/5/13
Read Re: closed universe, flat space?
Koobee Wublee
5/5/13
Read eight to the bar -- Daddy!
Brian Q. Hutchings

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.