Gravity as an emergent phenomenon

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Gravity as an emergent phenomenon

Pamela McCorduck
Great food for thought. Gravity might be no more than an emergent phenomenon:


http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss





"God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"

                        Melville, "Moby Dick"


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Re: Gravity as an emergent phenomenon

Roger Critchlow-2
And if you want to see if the argument confuses you as much as it confuses the physicists:


-- rec --

On Tue, Jul 13, 2010 at 10:39 AM, Pamela McCorduck <[hidden email]> wrote:
Great food for thought. Gravity might be no more than an emergent phenomenon:


http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss





"God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"

                       Melville, "Moby Dick"


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Re: Gravity as an emergent phenomenon

glen e. p. ropella-2
In reply to this post by Pamela McCorduck
Pamela McCorduck wrote circa 10-07-13 09:39 AM:
> http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss


“The end result was that everyone else didn’t understand it either,
including people who initially thought that did make some sense to
them,” he [Bousso] said in an e-mail message.

Sounds a lot like the end result of our discussions of "emergence". ;-)

--
glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com


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Re: Gravity as an emergent phenomenon

Robert J. Cordingley
In reply to this post by Pamela McCorduck
Stephen G will be glad to know too that the physicist featured in the
article thinks it might be all thermodynamics.  (or should that be
quantum thermodynamics?)
Robert C

On 7/13/10 10:39 AM, Pamela McCorduck wrote:

> Great food for thought. Gravity might be no more than an emergent phenomenon:
>
>
> http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss
>
>
>
>
>
> "God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"
>
> Melville, "Moby Dick"
>
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> lectures, archives, unsubscribe, maps at http://www.friam.org
>
>
>    

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Re: Gravity as an emergent phenomenon

Nick Thompson
In reply to this post by Pamela McCorduck
Pamela,

I got all ready to be huffy about the article, but then found it really
interesting.  At risk of going all professorial on you, I want to examine
your expression, "no more than a".   The most important phenomena that we
experience are all emergents.  If you hit me with a rock, the hardness  and
edginess of the rock that collapses my skull, are all emergents.  

So, then what the dickens is meant by "no more than"?  I think it means
SOMETHING and would like to explore it further with you (and others on the
list.)  "Reduction" means to some to account for a phenomenon n terms of
events or objects that are smaller than the phenomenon itself.  Reduction
is always to break a process or an object into its parts.  To others,
"reduction" means to explain a phenomenon by reference to a more familiar
or well understood phenomenon.  This latter understanding of reduction
opens the possibility for a reduction to refer to a process that is larger
or more inclusive than the process it reduces, what I would call an
up-reduction, to distinguish it from the "breaking-into-parts" sort of
reduction.  It sounds to me that the account of gravity being offered in
this article is a case of up reduction in that sense.  

I hope others will read the article and comment, because i wasnt sure I
understood it.

All the best,

Nick

 

Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology,
Clark University ([hidden email])
http://home.earthlink.net/~nickthompson/naturaldesigns/
http://www.cusf.org [City University of Santa Fe]




> [Original Message]
> From: Pamela McCorduck <[hidden email]>
> To: The Friday Morning Applied Complexity Coffee Group <[hidden email]>
> Date: 7/13/2010 12:39:41 PM
> Subject: [FRIAM] Gravity as an emergent phenomenon
>
> Great food for thought. Gravity might be no more than an emergent
phenomenon:
>
>
>
http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&em
c=rss
>
>
>
>
>
> "God keep me from ever completing anything. This whole book is but a
draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and
Patience!"
>
> Melville, "Moby Dick"
>
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> lectures, archives, unsubscribe, maps at http://www.friam.org



============================================================
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Re: Gravity as an emergent phenomenon

Russ Abbott
I always find myself confused about how to think about entropy. The article says that gravity is an entropic force. I understand that to mean that it not reducible to lower level forces but to be reducible (if that term applies) to statistical thermodynamics. 

Just as there are a lot more ways that a gas can be more or less uniformly distributed in a closed area than the ways it could be bunched up in a corner -- and hence we tend to find it more or less uniformly distributed -- gravity according to this analysis is like the universe in a more uniformly distributed state rather than a more unusual state.

There is no force that causes it. It is a statistical phenomenon. In other words, gravitational attraction is like whatever it is that pushes a gas bunched up in a corner to become more uniformly distributed.  But the whatever-it-is in the case of a gas is nothing but statistical phenomena. There are no forces involved even though from a naive point of view it may appear that there is a force that is pushing the gas to be spread out.


-- Russ



On Tue, Jul 13, 2010 at 10:36 AM, Nicholas Thompson <[hidden email]> wrote:
Pamela,

I got all ready to be huffy about the article, but then found it really
interesting.  At risk of going all professorial on you, I want to examine
your expression, "no more than a".   The most important phenomena that we
experience are all emergents.  If you hit me with a rock, the hardness  and
edginess of the rock that collapses my skull, are all emergents.

So, then what the dickens is meant by "no more than"?  I think it means
SOMETHING and would like to explore it further with you (and others on the
list.)  "Reduction" means to some to account for a phenomenon n terms of
events or objects that are smaller than the phenomenon itself.  Reduction
is always to break a process or an object into its parts.  To others,
"reduction" means to explain a phenomenon by reference to a more familiar
or well understood phenomenon.  This latter understanding of reduction
opens the possibility for a reduction to refer to a process that is larger
or more inclusive than the process it reduces, what I would call an
up-reduction, to distinguish it from the "breaking-into-parts" sort of
reduction.  It sounds to me that the account of gravity being offered in
this article is a case of up reduction in that sense.

I hope others will read the article and comment, because i wasnt sure I
understood it.

All the best,

Nick



Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology,
Clark University ([hidden email])
http://home.earthlink.net/~nickthompson/naturaldesigns/
http://www.cusf.org [City University of Santa Fe]




> [Original Message]
> From: Pamela McCorduck <[hidden email]>
> To: The Friday Morning Applied Complexity Coffee Group <[hidden email]>
> Date: 7/13/2010 12:39:41 PM
> Subject: [FRIAM] Gravity as an emergent phenomenon
>
> Great food for thought. Gravity might be no more than an emergent
phenomenon:
>
>
>
http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&em
c=rss

>
>
>
>
>
> "God keep me from ever completing anything. This whole book is but a
draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and
Patience!"
>
>                       Melville, "Moby Dick"
>
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> lectures, archives, unsubscribe, maps at http://www.friam.org



============================================================
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Re: Gravity as an emergent phenomenon

Owen Densmore
Administrator
In reply to this post by Pamela McCorduck
Great catch, thanks.

Time for a new book?  :)

    -- Owen


On Jul 13, 2010, at 10:39 AM, Pamela McCorduck wrote:

> Great food for thought. Gravity might be no more than an emergent phenomenon:
>
> http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss
>
> "God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"
>
> Melville, "Moby Dick"


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Re: Gravity as an emergent phenomenon

glen e. p. ropella-2
In reply to this post by Roger Critchlow-2
Roger Critchlow wrote circa 10-07-13 09:55 AM:
> And if you want to see if the argument confuses you as much as it
> confuses the physicists:
>
> http://arxiv.org/abs/1001.0785

So far (section 3.2), I'm getting that same tickle in my lizard brain
that I get when I play numerologist.  "Do you see?  When I take this
number and add it to that one, then shift them around, add the digits
together, fold in the position of the moon, and say a prayer to Satan,
we end up with the magic number 22!  Do you see!?!?"

--
glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com


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Re: Gravity as an emergent phenomenon

Robert J. Cordingley
In reply to this post by Pamela McCorduck
Then for something really complicated (complex?) this article on
microbiology/micobiomes made me think I'm just a host for all the
millions of symbiotes?  Literally your right hand might not know what
your left hand is doing.
http://www.nytimes.com/2010/07/13/science/13micro.html?ref=science
Persons with a sensitive nature may get grossed out about references to
certain emergent phenomenon and other procedures.
Thanks
Robert C


On 7/13/10 10:39 AM, Pamela McCorduck wrote:

> Great food for thought. Gravity might be no more than an emergent phenomenon:
>
>
> http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss
>
>
>
>
>
> "God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"
>
> Melville, "Moby Dick"
>
>
> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> lectures, archives, unsubscribe, maps at http://www.friam.org
>
>
>    

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Re: Gravity as an emergent phenomenon

Carl Tollander
In reply to this post by glen e. p. ropella-2
Sabine Hossenfelder's summations are fun and interesting and, alas more
informative than the nyt article:
http://backreaction.blogspot.com/2010/03/gravity-is-entropy-is-gravity-is.html
http://backreaction.blogspot.com/2010/07/in-praise-of-black-holes.html

Carl

On 7/13/10 10:55 AM, glen e. p. ropella wrote:

> Pamela McCorduck wrote circa 10-07-13 09:39 AM:
>> http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss 
>>
>
>
> “The end result was that everyone else didn’t understand it either,
> including people who initially thought that did make some sense to
> them,” he [Bousso] said in an e-mail message.
>
> Sounds a lot like the end result of our discussions of "emergence". ;-)
>

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Re: Gravity as an emergent phenomenon

Paul Paryski
In reply to this post by Robert J. Cordingley
Herr Prof. Thompson,

Would you  "reductionally posit that our personalities are emergent?
Paul



-----Original Message-----
From: Robert J. Cordingley <[hidden email]>
To: The Friday Morning Applied Complexity Coffee Group <[hidden email]>
Sent: Tue, Jul 13, 2010 1:11 pm
Subject: Re: [FRIAM] Gravity as an emergent phenomenon

Then for something really complicated (complex?) this article on microbiology/micobiomes made me think I'm just a host for all the millions of symbiotes? Literally your right hand might not know what your left hand is doing. 
http://www.nytimes.com/2010/07/13/science/13micro.html?ref=science 
Persons with a sensitive nature may get grossed out about references to certain emergent phenomenon and other procedures. 
Thanks 
Robert C 
 
On 7/13/10 10:39 AM, Pamela McCorduck wrote: 
> Great food for thought. Gravity might be no more than an emergent phenomenon: 


> http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss 





> "God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!" 

> Melville, "Moby Dick" 


> ============================================================ 
> FRIAM Applied Complexity Group listserv 
> Meets Fridays 9a-11:30 at cafe at St. John's College 
> lectures, archives, unsubscribe, maps at http://www.friam.org 


>  
============================================================ 
FRIAM Applied Complexity Group listserv 
Meets Fridays 9a-11:30 at cafe at St. John's College 
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Re: Gravity as an emergent phenomenon

Pamela McCorduck
Nick, I love it when you talk professor-ese to me.

"No more than" = well, I dunno what. I found the article provocative, but if the best physicists don't quite understand what the guy is on about, I needn't feel bad for myself.

Pamela


"God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"

                        Melville, "Moby Dick"


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Re: Gravity as an emergent phenomenon

Owen Densmore
Administrator
In reply to this post by Pamela McCorduck
From Carl's post's post (backreaction):
In this case however one finds that the "temperature" can be negative and 
that the "entropy" can decrease without having to do work.

Whoa! Definitely relates to complexity babble!

    -- Owen


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Re: Gravity as an emergent phenomenon

glen e. p. ropella-2

So, Verlinde lost me in section 4.  But I usually try to continue
reading even if I don't understand (just like I continue talking about
stuff I don't understand ;-).  And equation 5.35 (attached) had a
surprise for me.  What is that ^ symbol between dx^a and dx^b?

--
glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com


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eq-5.35.png (9K) Download Attachment
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Re: Gravity as an emergent phenomenon

Roger Critchlow-2
Working from the context, I'd guess: the tensor product between the components <i>dx<sup>a</sup></i> and <i>dx<sup>b</sup></i>of the stress energy tensor <i>T<sub>ab</sub></i>, but I've never been too sure about tensors.

I was lost in the introduction.

The proposition of entropy causing action at a distance reminded me of a notorious demonstration.  A beaker of water and a beaker of sugar dissolved in water are sealed together inside a bell jar.  Over time the level of liquid in the beaker of water will drop and the level of liquid in the beaker of sugar water will rise. 

-- rec --

On Tue, Jul 13, 2010 at 7:30 PM, glen e. p. ropella <[hidden email]> wrote:

So, Verlinde lost me in section 4.  But I usually try to continue reading even if I don't understand (just like I continue talking about stuff I don't understand ;-).  And equation 5.35 (attached) had a surprise for me.  What is that ^ symbol between dx^a and dx^b?


--
glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com


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Re: Gravity as an emergent phenomenon

Russ Abbott
Wonderful! I love the water/sugar example.


-- Russ



On Tue, Jul 13, 2010 at 9:07 PM, Roger Critchlow <[hidden email]> wrote:
Working from the context, I'd guess: the tensor product between the components <i>dx<sup>a</sup></i> and <i>dx<sup>b</sup></i>of the stress energy tensor <i>T<sub>ab</sub></i>, but I've never been too sure about tensors.

I was lost in the introduction.

The proposition of entropy causing action at a distance reminded me of a notorious demonstration.  A beaker of water and a beaker of sugar dissolved in water are sealed together inside a bell jar.  Over time the level of liquid in the beaker of water will drop and the level of liquid in the beaker of sugar water will rise. 

-- rec --

On Tue, Jul 13, 2010 at 7:30 PM, glen e. p. ropella <[hidden email]> wrote:

So, Verlinde lost me in section 4.  But I usually try to continue reading even if I don't understand (just like I continue talking about stuff I don't understand ;-).  And equation 5.35 (attached) had a surprise for me.  What is that ^ symbol between dx^a and dx^b?


--
glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com


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Re: Gravity as an emergent phenomenon

Russell Standish
In reply to this post by Roger Critchlow-2
On Tue, Jul 13, 2010 at 10:07:14PM -0600, Roger Critchlow wrote:
> Working from the context, I'd guess: the tensor product between the
> components <i>dx<sup>a</sup></i> and <i>dx<sup>b</sup></i>of the stress
> energy tensor <i>T<sub>ab</sub></i>, but I've never been too sure about
> tensors.
>

Not a tensor product, but an exterior product. It's somewhat related to
a cross product of two 3D vectors.

Cheers


--

----------------------------------------------------------------------------
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Mathematics                        
UNSW SYDNEY 2052                 [hidden email]
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Re: Gravity as an emergent phenomenon

Grant Holland
In reply to this post by Pamela McCorduck
Verlinde makes the same unfortunate argument that is made by scores of scientists - even noted thermodynamicsists - about so-called "disorder": namely that certain permutations are "disordered", while other permutations are not. To wit:

"Think of the universe as a box of scrabble letters. There is only one way to have the letters arranged to spell out the Gettysburg Address, but an astronomical number of ways to have them spell nonsense. Shake the box and it will tend toward nonsense, disorder will increase and information will be lost as the letters shuffle toward their most probable configurations. Could this be gravity?"

I find this argument specious.

Just because, from an anthropomorphic, English-speaking bias, he finds the Gettysburg address "more ordered" than any other permutation of the same length - it is not. They are all permutation of the same number of letters. Each is as well-defined, and well-ordered, as the other.

Anyway, "order" is an ill-defined, conflated term within the discussion of thermodynamics. It enjoys two distinct usages that get oft-conflated in the conversation regarding entropy. One usage is that it means "disorganization", "absence of arrangement", "dispersed", etc. This is approximately the meaning had originally by R. Clausius. The other usage is that of  "uncertainty" or "unpredictability".  This is the meaning had by Shannon. "Disorganized" and "uncertain" do not mean the same thing. I can prove this because they can vary independently - and, the same phenomenon can exhibit one without the other - the Organized state can sometimes be Uncertain...

In between the meanings of Clausius and Shannon are the meanings of entropy put forth by Boltzmann and Gibbs. Those meanings are often taken to be about "disorganization", but they are actually about "uncertainty". They involve probabilities. So, there is much confusion within statistical thermodynamics about "entropy", because the conversation often assumes that "disorder" is about "disorganization", when it is actually about "unpredictability". Certainly, it is confusing since Clausius was all about "dispersion",  "disorganization", while these other two physicists, Boltzmann and Gibbs, were actually about "uncertainty".

On the other hand, Shannon was not behaving as a physicist, when he "borrowed" the word "entropy" (upon the insistence of von Neumann) for his measure of uncertainty. Indeed, he even "borrowed" most of his formula from Gibbs. However, with his definition of entropy, Gibbs ( and Boltzmann before him) was doing physics - he was describing a specific physical phenomenon.

On the other hand, Shannon was not doing physics. Rather he was doing mathematical statistics. His definition of entropy is a mathematical function whose domain space is probability distributions (to use the term loosely). With Shannon's entropy, any probability distribution now has a "measure of unpredictability". Some PDFs have more unpredictability built into them than others, and he measures it.

Harold Morowitz also makes this point:

[Shannon’s entropy] is a meaningful measure over any probability distribution, while [Gibb’s thermodynamic entropy] has meaning only if the pi are the probabilities of a system being in the ith quantum state when the system is at equilibrium, as rigorously defined for thermodynamics….[Shannon’s entropy] is a measure on a probability distribution; it is not a physical quantity.” [Morowitz 1992]

This is obviously a pet peeve of mine. Welcome any comments!

Grant

Pamela McCorduck wrote:
Great food for thought. Gravity might be no more than an emergent phenomenon:


http://www.nytimes.com/2010/07/13/science/13gravity.html?_r=1&partner=rss&emc=rss





"God keep me from ever completing anything. This whole book is but a draft--nay, but the draft of a draft. Oh, Time, Strength, Cash, and Patience!"

			Melville, "Moby Dick"


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-- 
Grant Holland
VP, Product Development and Software Engineering
NuTech Solutions
404.427.4759

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Re: Gravity as an emergent phenomenon

David Eric Smith
In reply to this post by glen e. p. ropella-2
Hi Glen,

I believe it's also called a "wedge product".  Mike Spivak's tiny but  
frustrating but elegant book Calculus on Manifolds, if I remember  
correctly, defines these things and explains what they mean in  
geometric terms.

Eric





On Jul 13, 2010, at 7:30 PM, glen e. p. ropella wrote:

>
> So, Verlinde lost me in section 4.  But I usually try to continue  
> reading even if I don't understand (just like I continue talking  
> about stuff I don't understand ;-).  And equation 5.35 (attached)  
> had a surprise for me.  What is that ^ symbol between dx^a and dx^b?
>
> --
> glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com
>
> <eq-5.35.png>=========================================================
> ===
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> lectures, archives, unsubscribe, maps at http://www.friam.org


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Re: Gravity as an emergent phenomenon

Nick Thompson
In reply to this post by Pamela McCorduck
Roger,
 
Some how that seems less mysterious if you say, seal a beaker of SUGAR and a beaker of water in a bell jar.  In time the sugar will become damp.  By the way, help me out with the technology, here.  Initially, what is the atmosphere in the bell jar composed of? 
 
Nick
 
Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology,
Clark University ([hidden email])
http://www.cusf.org [City University of Santa Fe]
 
 
 
 
----- Original Message -----
Sent: 7/14/2010 12:07:45 AM
Subject: Re: [FRIAM] Gravity as an emergent phenomenon

Working from the context, I'd guess: the tensor product between the components <i>dx<sup>a</sup></i> and <i>dx<sup>b</sup></i>of the stress energy tensor <i>T<sub>ab</sub></i>, but I've never been too sure about tensors.

I was lost in the introduction.

The proposition of entropy causing action at a distance reminded me of a notorious demonstration.  A beaker of water and a beaker of sugar dissolved in water are sealed together inside a bell jar.  Over time the level of liquid in the beaker of water will drop and the level of liquid in the beaker of sugar water will rise. 

-- rec --

On Tue, Jul 13, 2010 at 7:30 PM, glen e. p. ropella <[hidden email]> wrote:

So, Verlinde lost me in section 4.  But I usually try to continue reading even if I don't understand (just like I continue talking about stuff I don't understand ;-).  And equation 5.35 (attached) had a surprise for me.  What is that ^ symbol between dx^a and dx^b?


--
glen e. p. ropella, 971-222-9095, http://agent-based-modeling.com


============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org


============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
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