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Originally Posted By: Bill
Actually it would appear as an expanding and contracting circle.


Surely, it would appear as a circle only if you had a third dimension from which to view it; in which case it would appear as a sphere!

Quote:
For a pure flatland to become 3 dimensional would require what I would think of as magic, since there is nothing there to expand into.


Would the same not apply to the universe?
Probably that is why you said that the extra dimension would have to be there all the time, but then you run into the problems of compactification, folding shadows etc.


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Originally Posted By: Bill S.
Originally Posted By: Bill

Actually it would appear as an expanding and contracting circle.

Surely, it would appear as a circle only if you had a third dimension from which to view it; in which case it would appear as a sphere!

No, in flatland it would appear as a circle, a round area completely enclosed by a line, with no entrance or exit. It would be possible to go completely around it and see that it had a continuous smooth curve. That is it would have the same curvature at all points. That may not be the standard definition of a circle, but it would define it for flatlanders who couldn't see it from above.

I'm not sure what to say about your other comment. I don't have a problem with the universe that we know, because it presumably had at least 3 dimensions right from the start. I have no idea how a dimension could be created from nothing. Of course I have no idea how our universe was created from nothing. But then not even the theorists studying it really have any idea.

And I don't have much faith in the so called String Theory. It just seems to be to be over complicated, with no way to find out where our universe would fit into it. So as far as compactification of dimensions is concerned I have my doubts that it really happens. I would feel much better about a theory of everything that just had our standard 3 + 1 dimensions. Which obviously hasn't kept me from talking about other ideas.

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Originally Posted By: Bill
in flatland it would appear as a circle.....it would define it for flatlanders who couldn't see it from above.


Precisely my point: Flatlanders would not be able to see it as a circle. The only way they would know it was a circle would be to feel its roundness.

Of course, there are "vertical" versions of 2D space in which it is easy to suppose that a circle would be visible, but a little reflection establishes that such is not the case. A third dimension would still be needed to see the circle.


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Originally Posted By: Bill
it presumably had at least 3 dimensions right from the start.


This seems to be a point on which we agree entirely. smile

I too have problems with the idea of creating dimensions, but I also have problems with rolling them up, or compacting them.


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Well, seeing its roundness is exactly how a flatlander would see a circle. That is how a flatlander would define a circle. To them the view of a 3 dimensional sphere passing through would be what they would interpret as an expanding and contracting circle. It doesn't matter how we would see it, they see it as a continuous, equally curved impenetrable "wall". After all they wouldn't be able to "see" a square, or a rectangle, or a triangle, or any randomly shaped form except by sensing it's shape. After all in the book that is how they tell the difference between people, by their shape.

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So, how many Flatlanders can dance on the circumference of a circle? And would they believe in a flat heaven, hell, and god? laugh

Last edited by Revlgking; 05/08/11 12:00 PM.

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Originally Posted By: Bill
After all they wouldn't be able to "see" a square, or a rectangle, or a triangle, or any randomly shaped form except by sensing it's shape. After all in the book that is how they tell the difference between people, by their shape.


Precisely; that's what made women so dangerous. smile

However, unless you had time and opportunity to "walk" round the shape, any shape, all you would see would be either a straight line or a point.


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Originally Posted By: Rev
would they believe in a flat heaven, hell, and god?


I think you could make an interesting analogy between God and the occupant of Pointland, if you wanted to.

I look forward to hearing Kallog's take on that.


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There is some very important things you miss in this discussion.

If our standard model of physics is right we have a mesh on the fabric of spacetime at plank distance and plank time units.

Now consider a particle moving at an angle like 45 degree to the mesh ... this is the jaggies problem of computer graphics display (http://en.wikipedia.org/wiki/Jaggies)

How does a particle pull off this trick of doing right angle jaggie movement on the plank time and plank distance fabric.

One view is thats why we have quantum mechanics because it has temporarily disappear off the spacetime mesh to come back again.

Another is the mesh is actually an illusion itself.

Ask any computer gamer who has played world of warcraft, rifts, or second life if you can have an illusion of 3D. If all you senses fed back in your visual illusion it would become hard to pick it from reality.

This problem goes back to the cave allegory from plato (http://en.wikipedia.org/wiki/Allegory_of_the_Cave)


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Well, Orac, you have come up with some interesting views. As far as the movement of particles on the fabric of spacetime. Some people have speculated that the particles are actually just configurations of the mesh, and their movement is an evolution of the mesh. Actually this is one of the areas where I don't have a great deal of faith in what anyone says. I think that everybody is kind of stabbing in the dark hoping to hit on something that will provide a good description of the way the universe works at the smallest (Planck) scales.

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Even with string theory they don't really deal with how you conserve energy and momentum of particles when it is crossing at some angle to the 3D flywire plank distance mesh we are supposedly dragging through a higgs particle ocean.

Unfortunately for me I have to try and model this stuff and this nasty little side effect of having a grid really hasn't hit the radar of the physicists.

Basically you end up at one of three places

1.) We have a 3D mesh at plank distances universe and something like string theory, higgs oceans etc exist.

Explains gravity easily but motion on the grid is problematic.


2.) We have a universe that is fractal based and you can zoom in indefinitely.

Very difficult to factor gravity in but easy to have particle motions at angles because nothing changes

3.) The universe is a hologram.

Strangely this is the easiest to model because 3D worlds on computer programs are very very common. I am not convinced it's reality but it feels like home sometimes :-)


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Originally Posted By: Orac
3.) The universe is a hologram.


One thing about which I am unclear where the holographic universe is concerned is what its supporters actually mean. There seem to be two possible interpretations:

1. The Universe really is a hologram.

2. The holograms we produce are in some way analogous to the way in which the Universe works.

I am inclined to think that the second of these is more likely to be correct, but I would be interested to hear what others think.


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Originally Posted By: Orac

Unfortunately for me I have to try and model this stuff and this nasty little side effect of having a grid really hasn't hit the radar of the physicists.

That sounds interesting. It may not actually be physics, but it is physics related, so could you give us some idea of what you do?

Bill Gill


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Originally Posted By: Bill S.

One thing about which I am unclear where the holographic universe is concerned is what its supporters actually mean. There seem to be two possible interpretations:

1. The Universe really is a hologram.

2. The holograms we produce are in some way analogous to the way in which the Universe works.


Yes I don't really like number 1 it's really easy to create and model because it really is nothing more than a 3D computer game but that is also it's weakness it implies that there is something and/or someone behind the illusion.
Maybe the matrix was right :-) Number 1 is not really a physics world interpretation.

There are a couple of theories that produce number 2.

D-Branes in string theory is probably the most compelling interpretation I have seen. It is probably the hologram version I feel most at home in.

I am not sure my english will hold up to explaining it but can have a go if you really want. It's probably best to read up on it, Briane Greene does a reasonable job in the book "The Fabric of the Cosmos: Space, Time, and the Texture of Reality". Be warned I really dislike his discussion of the spinning bucket in the book for me he never covers it's importance. It does create for me some degree of confidence in that you can get gauge theory, gravity a 3 dimensional world and all the basics I am familar with.

On the reverse I find the interpretation in quantum gravity the most contrived. They are so pre-occupied with gravity that some of the other basics end up sort of tagged in and by the old occam's razor they don't look right to me.

That's sort of my view on it in my best english I can muster ... sorry.


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Originally Posted By: Bill

That sounds interesting. It may not actually be physics, but it is physics related, so could you give us some idea of what you do?


I am not sure it's that exciting .... :-)

String theory analysis for example is almost entirely a mathematically excercise. I have still yet to see M-string theory incorporated properly it is just so dam complex.

Some of the more basic ones like MOND (http://en.wikipedia.org/wiki/Modified_Newtonian_dynamics) are much easier to model but I really can't see where this goes with Quantum Mechanics it's sort of still there like the ugly duckling it is with GR.

In my area there is much more work around trying to model conditions in and around the big bang or inflationary period depending on your view of which theory.

The reason is simple much bigger discoveries to be made ... Nobel prizes await.

My world of modelling is much more mundane we are looking closely at the operation of the theory at the plank distance because thats the key distance things get interesting. No nobel prizes given for proving or disproving someone elses theory usually :-)

Much more interesting boundaries for theories exist such as black holes and the boundary of the universe but they are even more inaccessible to us.

At the end of the day I am however a computer programmer with a physics background not a physicist who does programming so some of the stuff gets way beyond my ability at physics.

Mine physics knowledge is made usually from trying to help physicists feed model simulations into the computers and I usually end up asking a lot of questions.

There are a rare few who are great physics theorists and very good on computer programming.

My real work usually looks like trying to decipher weird drawings and scribbles on rather tattered and torn paper, drinking lots of coffee and pulling lots of hair out as either the simulation wont run or the phycisist doesn't liek the result :-)


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Well,Orac you may not be a physicist, but it sounds like you are plugged into the physics community. I have a BS in physics, but that doesn't get me very far. Most of what I have been spouting has been what I have tried to understand in a lot of reading I have been doing for the last 30 years. I hope you can keep on helping us understand what we are trying to talk about.

I expect that your physicist co-workers learn from trying to explain it to you. Explaining what you are doing is a great way to learn more about what you think you already know.

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Leonard Susskind did explain String Theory. I am so happy that Stanford University post it up in youtube. It is a good guide.

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SUSY and most of string theory looks to being read it's last rites from the LHC.

Quantum loop gravity is gone ... it's getting pretty light on for theories left standing :-)


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I have had serious doubts about string theory ever since I read Brian Green's "The Elegant Universe". He explained it in pretty good detail, except that nobody could figure out how to make it apply to the universe as it is. All they had was a huge bunch of possible universes. And since then nobody has been able to come up with anything better. I think the only thing they ever came up with that seemed to intersect with this universe was that it had a spin 2 particle, which matches what QM theorists have said the graviton would have. Unless they come up with something more than that they are going to have a hard time convincing me.

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Conference is on today

http://www.physorg.com/news/2011-08-lhc-latest-results-mumbai-conference.html
http://www.science20.com/quantum_diaries_survivor/new_atlas_limits_higgs_mass-81880


Thats most of string theory gone leaves only light higgs possible around 135 GEV but unlikely which is a few weird variants and a few light higgs models.

Otherwise you are up to a very heavy Higgs but the air is getting very stratified.

So the LHC says

no string/brane exotica,
no sparticles,
no WIMPs,
no supersymmetry exotica,
no extra-dimensions,
no mini-black holes,
no Randall-Sundrum gravitons,
no heavy Higgs,

Standard model holding.

Last edited by Orac; 08/22/11 07:27 PM.

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