Science > Physics > A Journey into Gravity and Spacetime (& a question)
| Topic: |
Science > Physics |
| User: |
"Brutus" |
| Date: |
29 Jul 2007 05:36:33 AM |
| Object: |
A Journey into Gravity and Spacetime (& a question) |
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/dp/0716760347/ref=sr_1_1/103-2291628-2691856?ie=UTF8&s=books&qid=1185703411&sr=8-1
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
than other newbie GR books like Geroch's "General Relativity
from A to B" or Clifford's "Was Einstein Right?" I own both too.
And the most amazing is that Wheeler's "A Journey into
Gravity and Spacetime only costs around $2. That is. The
1999 soft edition selling for $54 has the same contents as the
1990 hardbound edition. The latter is only being sold for
as low as $2 (where I got mine) and there are half a dozen
selling for around $3 in amazon marketplace section. The
book is in full color. Amazing!
Anyway. I have a question about a topic in the book. It
concerns "boundary of a boundary".. I wonder what official
name is it called in differential geometry or GR Proper. The
descriptions of it is herein described by one of the
reviewers at amazon:
"Most difficult for a layman to understand is how spacetime
acts on masive objects, but the author explains it brilliantly
in the next chapter, taught via the concept of "momenergy".
This entity is a 4-vector, and the author uses it to show
how its creation in a spacetime region can be written as
the sum of 8 terms, reflecting the fact that the "boundary"
of a four-dimensional block in spacetime consists of eight
three-dimensional cubes. That the contents of these cubes
sum to zero is the famous "boundary of a boundary is zero",
which is discussed in the next chapter. This chapter is one
of the best explanations ever given (at this level) of the
physics behind spacetime curvature and massive objects.
The actual mathematical quantification of curvature is
detailed in chapters 8 and 9, using elementary mathematics.
The author discusses nicely the famous Scharwzschild geometry.".
So what topics does the "boundary of a boundary" officially
fall under in General Relativity Proper? The author may be
use non-standard terms such as when he called "free fall"
as "free float" because free fall would denote something
is falling so "free float" is just semantically more accurate.
But what about 'boundary of a boundary"? Thanks.
Bru
At only $2, hope it can be included in Baez reading list for
newbie books on GR. Had he listed it before, I could have
bought it earlier. The book is great for our home idiots too
like Pentcho, Shubee, Seto and others I found when
searching the archives for infos.
.
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| User: "Martin Hogbin" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 08:03:57 AM |
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"Brutus" <brutusrelativity@yahoo.com> wrote in message news:1185705393.976475.194990@g12g2000prg.googlegroups.com...
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/dp/0716760347/ref=sr_1_1/103-2291628-2691856?ie=UTF8
&s=books&qid=1185703411&sr=8-1
"Most difficult for a layman to understand is how spacetime
acts on masive objects, but the author explains it brilliantly
in the next chapter, taught via the concept of "momenergy".
This entity is a 4-vector, and the author uses it to show
how its creation in a spacetime region can be written as
the sum of 8 terms, reflecting the fact that the "boundary"
of a four-dimensional block in spacetime consists of eight
three-dimensional cubes. That the contents of these cubes
sum to zero is the famous "boundary of a boundary is zero",
which is discussed in the next chapter. This chapter is one
of the best explanations ever given (at this level) of the
physics behind spacetime curvature and massive objects.
The actual mathematical quantification of curvature is
detailed in chapters 8 and 9, using elementary mathematics.
The author discusses nicely the famous Scharwzschild geometry.".
So what topics does the "boundary of a boundary" officially
fall under in General Relativity Proper?
I believe it is based in the exterior differential forms of
Elie Cartan.
Martin Hogbin
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| User: "Sam Wormley" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 12:32:33 PM |
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Brutus wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/dp/0716760347/ref=sr_1_1/103-2291628-2691856?ie=UTF8&s=books&qid=1185703411&sr=8-1
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
than other newbie GR books like Geroch's "General Relativity
from A to B" or Clifford's "Was Einstein Right?" I own both too.
And the most amazing is that Wheeler's "A Journey into
Gravity and Spacetime only costs around $2. That is. The
1999 soft edition selling for $54 has the same contents as the
1990 hardbound edition. The latter is only being sold for
as low as $2 (where I got mine) and there are half a dozen
selling for around $3 in amazon marketplace section. The
book is in full color. Amazing!
Anyway. I have a question about a topic in the book. It
concerns "boundary of a boundary".. I wonder what official
name is it called in differential geometry or GR Proper. The
descriptions of it is herein described by one of the
reviewers at amazon:
"Most difficult for a layman to understand is how spacetime
acts on masive objects, but the author explains it brilliantly
in the next chapter, taught via the concept of "momenergy".
This entity is a 4-vector, and the author uses it to show
how its creation in a spacetime region can be written as
the sum of 8 terms, reflecting the fact that the "boundary"
of a four-dimensional block in spacetime consists of eight
three-dimensional cubes. That the contents of these cubes
sum to zero is the famous "boundary of a boundary is zero",
which is discussed in the next chapter. This chapter is one
of the best explanations ever given (at this level) of the
physics behind spacetime curvature and massive objects.
The actual mathematical quantification of curvature is
detailed in chapters 8 and 9, using elementary mathematics.
The author discusses nicely the famous Scharwzschild geometry.".
So what topics does the "boundary of a boundary" officially
fall under in General Relativity Proper? The author may be
use non-standard terms such as when he called "free fall"
as "free float" because free fall would denote something
is falling so "free float" is just semantically more accurate.
But what about 'boundary of a boundary"? Thanks.
Bru
At only $2, hope it can be included in Baez reading list for
newbie books on GR. Had he listed it before, I could have
bought it earlier. The book is great for our home idiots too
like Pentcho, Shubee, Seto and others I found when
searching the archives for infos.
First, I would like you to look at:
http://mathworld.wolfram.com/Four-Vector.html
http://www.google.com/search?q=Four-Vector+site%3Ascienceworld.wolfram.com
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| User: "Tom Roberts" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
30 Jul 2007 01:08:53 PM |
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Brutus wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/dp/0716760347/ref=sr_1_1/103-2291628-2691856?ie=UTF8&s=books&qid=1185703411&sr=8-1
I've not seen this book. Perhaps I'll look for it.
So what topics does the "boundary of a boundary" officially
fall under in General Relativity Proper?
The Bianchi Identities. They are differential identities expressing
Wheeler's statement "the boundary of a boundary is zero". This is also
related to the generalized Stokes theorem.
Tom Roberts
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| User: "Brutus" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
30 Jul 2007 06:41:52 PM |
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On Jul 31, 2:08 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
Brutus wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I've not seen this book. Perhaps I'll look for it.
You must. It is light years better than Geroch's "GR from A to B"
as far as layman books for GR is concerned. It is in full color
in every page and costs only $2. The $2 1990 hardcopy edition
has exact same contents as the $54 1999 softcopy edition as
there is never a second edition so they are similar.
So what topics does the "boundary of a boundary" officially
fall under in General Relativity Proper?
The Bianchi Identities. They are differential identities expressing
Wheeler's statement "the boundary of a boundary is zero". This is also
related to the generalized Stokes theorem.
Tom Roberts
According to the book:
(Sum of moments of rotations for the faces of a little 3-cube) =
8pi x (amount of momenergy within the 3-cube)
which Wheeler called the Einstein-Cartan equation. Now
referring to wikipedia:
"Einstein-Cartan theory in theoretical physics extends general
relativity, to handle spin angular momentum correctly.
As the master theory of classical physics general relativity has
one known flaw: it cannot describe "spin orbit coupling", that
is, exchange of intrinsic angular momentum (spin) and orbital
angular momentum. There is a qualitative theoretical proof
showing that general relativity must be extended to
Einstein-Cartan theory when matter with spin is present.".
Now question.
How many percentage roughly of General Relativists accept
the Einstein-Cartan theory?? 50%? 25%? 5%? 99%?
Bru
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| User: "" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 06:28:49 AM |
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On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
.
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| User: "Brutus" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 07:01:32 AM |
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On Jul 29, 7:28 pm, wrote:
On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
Who else (of reliable source) has good list of layman books for SR,
GR, QM, etc.? I thought it's only Baez who has them. I think
he reads hundreds of books and know which is junk and good
for us who can't afford that much money.
Bru
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| User: "" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 07:03:06 AM |
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On Jul 29, 10:01 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 7:28 pm, wrote:
On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
Who else (of reliable source) has good list of layman books for SR,
GR, QM, etc.? I thought it's only Baez who has them. I think
he reads hundreds of books and know which is junk and good
for us who can't afford that much money.
Just get free lectures on the web.
Bru
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| User: "Brutus" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 07:19:20 AM |
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On Jul 29, 8:03 pm, wrote:
On Jul 29, 10:01 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 7:28 pm, wrote:
On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
Who else (of reliable source) has good list of layman books for SR,
GR, QM, etc.? I thought it's only Baez who has them. I think
he reads hundreds of books and know which is junk and good
for us who can't afford that much money.
Just get free lectures on the web.
Bru- Hide quoted text -
what particular sites? for example, for weeks I've been
looking for the meaning of "parallel transport" in GR.
No sites share it until I found Wheeler book which
describes it in detail.
Anyway. All I'm saying is that the book is the best
GR layman book out there. Most recommends
Geroch General Relativity from A to B which isn't
good because it doesn't use words like "geodesics",
"parallel transport", etc. and I wasted one month
reading it from recommendation from Baez site.
Therefore for poor souls like Pentcho and Seto,
recommend them the right books and Wheeler
"A Journey into Gravity and Spacetime" may
give them the basics they need as well as the
insights.
Bru
- Show quoted text -- Hide quoted text -
- Show quoted text -
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| User: "" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 07:38:50 AM |
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On Jul 29, 10:19 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 8:03 pm, wrote:
On Jul 29, 10:01 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 7:28 pm, wrote:
On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
Who else (of reliable source) has good list of layman books for SR,
GR, QM, etc.? I thought it's only Baez who has them. I think
he reads hundreds of books and know which is junk and good
for us who can't afford that much money.
Just get free lectures on the web.
Bru- Hide quoted text -
what particular sites? for example, for weeks I've been
looking for the meaning of "parallel transport" in GR.
No sites share it until I found Wheeler book which
describes it in detail.
Google search edu sites. There are video lectures as well.
Anyway. All I'm saying is that the book is the best
GR layman book out there. Most recommends
Geroch General Relativity from A to B which isn't
good because it doesn't use words like "geodesics",
"parallel transport", etc. and I wasted one month
reading it from recommendation from Baez site.
Therefore for poor souls like Pentcho and Seto,
recommend them the right books and Wheeler
"A Journey into Gravity and Spacetime" may
give them the basics they need as well as the
insights.
Bru
- Show quoted text -- Hide quoted text -
- Show quoted text -
.
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| User: "deejey" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 12:46:37 PM |
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On Jul 29, 2:19 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 8:03 pm, wrote:
On Jul 29, 10:01 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 7:28 pm, wrote:
On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
Who else (of reliable source) has good list of layman books for SR,
GR, QM, etc.? I thought it's only Baez who has them. I think
he reads hundreds of books and know which is junk and good
for us who can't afford that much money.
Just get free lectures on the web.
Bru- Hide quoted text -
what particular sites? for example, for weeks I've been
looking for the meaning of "parallel transport" in GR.
No sites share it until I found Wheeler book which
describes it in detail.
Anyway. All I'm saying is that the book is the best
GR layman book out there. Most recommends
Geroch General Relativity from A to B which isn't
good because it doesn't use words like "geodesics",
"parallel transport", etc. and I wasted one month
reading it from recommendation from Baez site.
Therefore for poor souls like Pentcho and Seto,
i remember i read clever observations from
pentcho and seto
from you i remember nothen, you are inexistent
eat worms you foken hypocrite, as if not already
were enuff with hypocrites here
recommend them the right books and Wheeler
"A Journey into Gravity and Spacetime" may
give them the basics they need as well as the
insights.
Bru
- Show quoted text -- Hide quoted text -
- Show quoted text -
.
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| User: "Sam Wormley" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 07:21:03 PM |
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deejey wrote:
i remember i read clever observations from
pentcho and seto
See: http://www.albinoblacksheep.com/flash/youare.swf
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| User: "Uncle Al" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 06:28:57 PM |
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deejey wrote:
[snip crap]
i remember i read clever observations from
pentcho and seto
Milk squirts from Uncle Al's nostrils.
[snip rest of crap]
http://www.mazepath.com/uncleal/sunshine.jpg
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
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| User: "Brutus" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 07:12:50 AM |
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On Jul 29, 8:01 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
On Jul 29, 7:28 pm, wrote:
On Jul 29, 8:36 pm, Brutus <brutusrelativ...@yahoo.com> wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/d...
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
The real question is why someones book list matters to you. Lots of
other people keep lists of books they recommend too, would you like me
to forward your post to them?
Who else (of reliable source) has good list of layman books for SR,
GR, QM, etc.? I thought it's only Baez who has them. I think
he reads hundreds of books and know which is junk and good
for us who can't afford that much money.
Bru
Another, I've been trying to understand General Relativity
for a decade and couldn't even after reading Greene's Elegant
Universe.. until I found Wheeler's book a few days
ago. And it only costs $2 with full color illustration in
most pages. The book opens my mind to the reality that
GR is a physical phenomenon and has an objective reality.
Also I like Wheeler's poem:
"Oh Event.
Sparkling grain of sand
On the fabric of existence,
Oh Interval,
Gossamer tie
Between event and event,
You two tear away the clouds
Of "absolute space" and "absolute time"
And reveal to us spacetime -
Spacetime as doorway,
Doorway, daring traveller,
To the enormity
Of space and time
Open to our visitation.
:)
GR is like poetry indeed. It opens our mind and heart.
Also I think GR is God Himself. He (or Spacetime) is all
around us. He is everywhere. Spacetime is He who
ever watches us down the ages and from the beginning of
time.
Hope I'm not being duped by relativity hypnotists, lol.
Bru
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| User: "Jim Black" |
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| Title: Re: A Journey into Gravity and Spacetime (& a question) |
29 Jul 2007 10:08:48 PM |
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On Sun, 29 Jul 2007 03:36:33 -0700, Brutus wrote:
http://www.amazon.com/Journey-Gravity-Spacetime-Scientific-American/dp/0716760347/ref=sr_1_1/103-2291628-2691856?ie=UTF8&s=books&qid=1185703411&sr=8-1
I got this amazing newbie book a few days ago. Why didn't anyone
recommend it nor is it in Baez reading list? It's even better
than other newbie GR books like Geroch's "General Relativity
from A to B" or Clifford's "Was Einstein Right?" I own both too.
And the most amazing is that Wheeler's "A Journey into
Gravity and Spacetime only costs around $2. That is. The
1999 soft edition selling for $54 has the same contents as the
1990 hardbound edition. The latter is only being sold for
as low as $2 (where I got mine) and there are half a dozen
selling for around $3 in amazon marketplace section. The
book is in full color. Amazing!
Anyway. I have a question about a topic in the book. It
concerns "boundary of a boundary".. I wonder what official
name is it called in differential geometry or GR Proper. The
descriptions of it is herein described by one of the
reviewers at amazon:
"Most difficult for a layman to understand is how spacetime
acts on masive objects, but the author explains it brilliantly
in the next chapter, taught via the concept of "momenergy".
This entity is a 4-vector, and the author uses it to show
how its creation in a spacetime region can be written as
the sum of 8 terms, reflecting the fact that the "boundary"
of a four-dimensional block in spacetime consists of eight
three-dimensional cubes. That the contents of these cubes
sum to zero is the famous "boundary of a boundary is zero",
which is discussed in the next chapter. This chapter is one
of the best explanations ever given (at this level) of the
physics behind spacetime curvature and massive objects.
The actual mathematical quantification of curvature is
detailed in chapters 8 and 9, using elementary mathematics.
The author discusses nicely the famous Scharwzschild geometry.".
So what topics does the "boundary of a boundary" officially
fall under in General Relativity Proper? The author may be
use non-standard terms such as when he called "free fall"
as "free float" because free fall would denote something
is falling so "free float" is just semantically more accurate.
But what about 'boundary of a boundary"? Thanks.
Bru
At only $2, hope it can be included in Baez reading list for
newbie books on GR. Had he listed it before, I could have
bought it earlier. The book is great for our home idiots too
like Pentcho, Shubee, Seto and others I found when
searching the archives for infos.
I don't remember the details, but Misner, Thorne, and Wheeler's
_Gravitation_ uses the exact same language, i.e. "the boundary of a
boundary is zero," in describing where the Bianchi identities come from.
--
Jim E. Black
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