Loop versus closed string?


by rtharbaugh1
Tags: loop, string, versus
Newbie says Hi
Newbie says Hi is offline
#19
Feb22-07, 09:50 AM
P: 43
Marcus, just out of curiosity, what type of researcher are you? String, loop, or something else?
Hans de Vries
Hans de Vries is offline
#20
Feb22-07, 10:02 AM
Sci Advisor
P: 1,136
Quote Quote by marcus View Post
I'm still hoping his absence is only temporary. Amazing guy:
dignity, humor, sensitivity, gentleness, thorough grasp of large parts of physics and mathematics, a knowledge of the classics too.
I never saw a limit to his curiosity.
Let's hope so indeed. An individual so full of live on a never ending quest.

From some of selfAdjoint's posts:

He’s a widower, living in the town of Greenville (Fox cities) Wisconsin,
probably the community of Menominee Falls, born in Maryland, August
7, 1933. Followed grad school at the University of Wisconsin in Mathematics
in the early 60's. He left grad school in 1966 and took a job as a programmer-
analyst at a manufacturing company, He met his wife Mary Ann at the
Christmas party of the department manager. Has a daughter named Pam born
on Aug 9th who did Industrial engineering at Marquette. He has a married son
with a 7 year old daughter Nikki born in Sep 1999 and 1 year old daughter
Elizabeth born on Dec 21 2005. He has lived also in Southern California,
Indiana and Illinois. He has been a Catholic for a major part of his live.



Regards, Hans.
marcus
marcus is offline
#21
Feb22-07, 01:13 PM
Astronomy
Sci Advisor
PF Gold
marcus's Avatar
P: 22,796
His life was gentle, and the elements so mixed in him,
that Nature might stand up, and say to all the world:
"This was a man."

======================
(Newbie, I'm retired. It doesn't matter any more but my training was in math, not primarily in physics.)
Kea
Kea is offline
#22
Feb22-07, 03:25 PM
P: 859
Quote Quote by marcus View Post
His life was gentle, and the elements so mixed in him,
that Nature might stand up...
Oh no, Marcus! He wasn't stabbed was he?
marcus
marcus is offline
#23
Feb22-07, 03:38 PM
Astronomy
Sci Advisor
PF Gold
marcus's Avatar
P: 22,796
Quote Quote by Kea View Post
Oh no, Marcus! He wasn't stabbed was he?
You mean like Caesar? I think not, Kea.
rtharbaugh1
rtharbaugh1 is offline
#24
Feb28-07, 12:17 PM
P: 310
sA has always been a good friend to me as long as I've known him, on this forum as well as on another before I came here. If I were in MN I'd drive down to Greenville to find out what is going on. I am also still hopeing his absence is temporary and that he will return to us.

Best wishes to all....
Richard
petm1
petm1 is offline
#25
Mar14-07, 12:16 AM
petm1's Avatar
P: 366
It is an old story to everyone here by now, but I will say again that it seems to me we have to accept that there are as many dimensions of time as there are of space. If I have understood correctly, the objection to this is mainly that we have no way of observing conditions along any of the time dimensions that we are not on. That is fair enough. If a time dimension is at right angles to the one we are on, the intersection would be nothing more than a single instant, and we would certainly have no way even in principle to detect such a thing.
I don't understand why someone who thinks that there are as many dimensions of time as there are of space would not see that even if a time dimension is at right angles to the one we are on and it would be only a instant, that that is how all instants are formed.

It isn't very satisfactory to suggest that we have no reason to believe that physics is any different along the orthogonal. So what? Even if they are there, they would have to be of negligible import. We would gain nothing by adding in a bunch of extra time elements. The one or two we have are all we need for anything we can observe.
If you think of time as leading motion then not only are you able to observe all, but you could also talk of potential as real, but at least a fifth dimension.

What could we hope to observe about a time-like singularity? It has no duration. Thinking in this fashion clearly leads to a dead end.
Thinking a time-like singularity has no duration clearly leads to a dead end, but thinking of a time like singularity as being contracted relative to us, and with as much energy compacted into a small space it could lead us to a better understanding for the foundation of matter. Charge would be easier to understand when you can show where the potential is. How about the electric-magnetic field, maybe its 3 dimensions of space and 3 dimensions of time in different combinations that makes it up. Six dimensions three of time with the potential for motion, and three of space with motion, tied at the hip but closer to reality than just four dimensions, I would think.
rtharbaugh1
rtharbaugh1 is offline
#26
Mar14-07, 07:45 PM
P: 310
Petm1

I see you have had a long discussion on 'time' over in the SR forum, and I took a look at that before going on here. In fact, I was thinking of coming back here, but not for speculations. You may know that idle speculation is frowned on here.

The SR forum discussion ended when Doc Al closed your thread, for what I consider to be good reasons. Further, this thread was about string vrs loop theory, in which I visited USCB and heard Gary Horowitz say that what is needed is a new physics, which he said requires a new view of the fundamental physical nature of time.

However the study of time is something that will require a new thread, in my opinion. It is likely to be a very difficult discussion, one in which ordinary language is part of the problem. I have been thinking of starting such a thread, but I will have to gather resources and lay down a groundwork first. I am not sure I am up to the task, now or ever, but certainly not now and not here.

Regards,

R.
petm1
petm1 is offline
#27
Mar15-07, 08:23 PM
petm1's Avatar
P: 366
rtharbaugh1,

Thanks for your reply, I can see that when talking about time it is all speculation.
rtharbaugh1
rtharbaugh1 is offline
#28
Mar16-07, 09:25 PM
P: 310
petm1
Your statement is probably an over generalization. All physics is based on measurement. Time can be measured. We do not have to speculate about what time it is, we can look at a clock. We do not have to speculate about how much time it takes a jet at mach1 to travel one mile, it can be calculated. Perhaps we can make theories about time which can be tested against measurables.

This thread is about the difference between strings and closed loops. I started it with that title because I still don't really feel I have a good answer. Time came into the thread because Dr. Horowitz speculated that a common problem in both string and loop theory might only be resolvable with new physics, which in his estimation, as I understand it, will require a new view of time.

So the problem of time is one common to string and loop, not likely to help me understand the difference between string and loop.

I have begun to look for current work on the topic of time in arXiv, but so far it seems difficult to find search terms that produce relevant results. A search for "spacetime and geometry" results in hundreds of papers, most of which are too deeply specialized to be helpful to me.

I want to start a new thread on the topic of time but first I want to find at least one reference for a starting point. It seems to me the problem is that time is ubiquitous, and like gravity for Newton, it has remained an undefined observable.

Wiki has an artical giving reference, including one in Further Reading to Rovelli, Carlo (2006). What is time, what space?. Di Renzo Editore, Roma

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

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

R


Register to reply

Related Discussions
open vs closed loop gain Electrical Engineering 4
Entangled closed oriented strings / closed string chains Beyond the Standard Model 1
Magnetic field in a closed loop Advanced Physics Homework 18
integral along a closed loop Calculus & Beyond Homework 2
Closed Loop General Astronomy 11