Extra Spatial Dimensions

______________________________________________________

Physicists at the University of Wisconsin-Madison have devised an approach that may help unlock the hidden shapes of alternate dimensions of the universe.

A new study demonstrates that the shapes of extra dimensions can be "seen" by deciphering their influence on cosmic energy released by the violent birth of the universe 13 billion years ago. The method, published 02/02/07 in Physical Review Letters, provides evidence that physicists can use experimental data to discern the nature of these elusive dimensions.

String theory, proposes that everything in the universe is made of tiny, vibrating strings of energy, to encompass the physical principles of all objects from immense galaxies to subatomic particles. Though currently the front-runner to explain the framework of the cosmos, the theory remains, to date, untested.

The mathematics of string theory suggests that the world we know is not complete. In addition to our four familiar dimensions (three-dimensional space and time) string theory predicts the existence of six extra spatial "hidden" dimensions curled in tiny geometric shapes at every single point in our universe.

Maybe you can't picture a 10-dimensional world. Our minds are accustomed to only three spatial dimensions and lack a frame of reference for the other six, says UW-Madison physicist Gary Shiu, who led the new study. Though scientists use computers to visualize what these six-dimensional geometries could look like (see image), no one really knows for sure what shape they take.


A computer-generated rendering of a possible six-dimensional geometry similar to those studied by UW-Madison physicist Gary Shiu. (Image: courtesy Andrew J. Hanson, Indiana University)

According to string theory mathematics, the extra dimensions could adopt any of tens of thousands of possible shapes, each shape theoretically corresponding to its own universe with its own set of physical laws. For our universe, Nature picked one.

The many-dimensional shapes are far too small to see or measure through any usual means of observation, which makes testing this crucial aspect of string theory very difficult.

Just as a shadow can give an idea of the shape of an object, the pattern of cosmic energy in the sky can give an indication of the shape of the other six dimensions present, Shiu explains.

To learn how to read telltale signs of the six-dimensional geometry from the cosmic map, they worked backward. Starting with two different types of mathematically simple geometries, called warped throats, they calculated the predicted energy map that would be seen in the universe described by each shape. When they compared the two maps, they found small but significant differences between them.

The results show that specific patterns of cosmic energy can hold clues to the geometry of the six-dimensional shape.

Story adapted from a news release by University of Wisconsin-Madison
more Physicists Find Way To 'See' Extra Dimensions from Science Daily
______________________________________________________
Calabi Yau from WMAP by Lubos Motl
Symmetry in psychological action by Plato
______________________________________________________
______________________________________________________

Universe mapping

The Chapter of Not Letting the Soul of a Man Be Snatched Away from Him: I, even I, am he who cometh forth from the Celestial Water (Akeb). He (Akeb) produced abundance for me, and hath the mastery there in the form of the River.

____________________________________________________
Papyri of Ani - evansville educ

Supersymmetry

In supersymmetric theories, every fundamental particle has a superpartner. If the vacuum state happens to be supersymmetric, this would mean superpartners would have the same mass as their ordinary partners, which is clearly ruled out by experiment. Hence, the vacuum must have broken supersymmetry. Either we assume the vacuum is degenerate and SUSY is broken spontaneously, or we add soft SUSY breaking terms which break SUSY explicitly, making it an approximate symmetry. The latter approach is often preferred.

To incorporate supersymmetry into particle physics, the Standard Model must be extended to include at least twice as many particles, since none of the particles in the Standard Model can be superpartners of each other, because they have incompatible masses and quantum numbers.

With the addition of the new particles, there are many possible new interactions. The simplest possible supersymmetric model consistent with the Standard Model is the Minimal Supersymmetric Standard Model (MSSM). However, the MSSM appears to be unnatural in a number of ways, and many physicists doubt that it will be the correct theory.

A possibility in some supersymmetric models is the existence of very heavy stable particles (such as neutralinos) which would be WIMPs (weakly interacting massive particles). These would be candidates for dark matter.
For more on Supersymmetry visit wikipedia



Evaluating extreme approaches
by Lubos Motl

Pic: Origin of the Universe
from plus maths org
_______________________________________________________

Bootstrap
In the context of quantum gravity, many of us more or less secretly believe another version of the bootstrap. I think that most of the real big shots in string theory are convinced that all of string theory is exactly the same thing as all consistent backgrounds of quantum gravity. By a consistent quantum theory of gravity, we mean e.g. a unitary S-matrix with some analytical conditions implied by locality or approximate locality, with gravitons in the spectrum that reproduce low-energy semiclassical general relativity, and with black hole microstates that protect the correct high-energy behavior of the scattering that can also be derived from a semi-classical description of general relativity, especially from the black hole physics.

The worldvolumes
are spacetimes of other string theories, and so on
The paradigm of multiple quantization is also closely related to another "big idea" that is probably the most favorite of mine in this whole list. Perturbative string theory shows that the fields in spacetime are not yet fundamental: they are described by states of a more fundamental theory that lives on the two-dimensional worldsheet. Now, the two-dimensional worldsheet is described by a two-dimensional gravitational conformal field theory. Although gravity can be more or less described by a local field theory in less than four dimensions - because it has no real physics in it - you could still argue that the right way to describe a gravitational theory should be in terms of string theory. The worldsheet should be a spacetime of another string theory. And perhaps, this step could continue infinitely many times.

More on black hole final state referencing by Plato
More on Evaluating extreme approaches by Lubos Motl
_______________________________________________________
_______________________________________________________
Quote of the Day:
The best way to make your dreams come true is to wake up.
Paul Valery more Famous Quotes
_______________________________________________________
_______________________________________________________

Panning for Gold

_____________________________________________
Panning for Gold conference slac stanford edu

Panning for gold and more about LHC by JoAnne from SLAC

Any discovery or non-discovery at the LHC has zero implications for strings or LQG. This is particularly true for the Higgs. The only true exception is if TeV scale strings are discovered - that has obvious implications for string theory. Some will claim victory for string theory if supersymmetry is discovered. However, TeV scale supersymmetry can exist quite happily on its own merits without strings, so the discovery of supersymmetry at the LHC does not imply that string theory is correct. Proof of the existence of supersymmetry is a necessary, but not sufficient condition for proof of the existence of strings. Also, keep in mind that string theory does not require that supersymmetry be present at the TeV scale.

Supersymmetry

In supersymmetric theories, every fundamental particle has a superpartner. If the vacuum state happens to be supersymmetric, this would mean superpartners would have the same mass as their ordinary partners, which is clearly ruled out by experiment. Hence, the vacuum must have broken supersymmetry. Either we assume the vacuum is degenerate and SUSY is broken spontaneously, or we add soft SUSY breaking terms which break SUSY explicitly, making it an approximate symmetry. The latter approach is often preferred.

For more on Supersymmetry visit wikipedia

_______________________________________________
Image: ALFRED T. KAMAJIAN @ essentia holographic spacetime

Information in the Holographic Universe:
A Holographic Spacetime By Jacob D. Bekenstein

TWO UNIVERSES of different dimension and obeying disparate physical laws are rendered completely equivalent by the holographic principle. Theorists have demonstrated this principle mathematically for a specific type of five-dimensional spacetime ("anti–de Sitter") and its four-dimensional boundary. In effect, the 5-D universe is recorded like a hologram on the 4-D surface at its periphery. Superstring theory rules in the 5-D spacetime, but a so-called conformal field theory of point particles operates on the 4-D hologram. A black hole in the 5-D spacetime is equivalent to hot radiation on the hologram--for example, the hole and the radiation have the same entropy even though the physical origin of the entropy is completely different for each case. Although these two descriptions of the universe seem utterly unalike, no experiment could distinguish between them, even in principle.

black hole final state referencing by Plato

The Black Hole Final State
Gary T. Horowitz (1) and Juan Maldacena (2)
(1) University of California at Santa Barbara, Santa Barbara CA 93106, USA
(2) Institute for Advanced Study Princeton, New Jersey 08540, USA

We propose that in quantum gravity one needs to impose a final state boundary condition at black hole singularities. This resolves the apparent contradiction between string theory and semiclassical arguments over whether black hole evaporation is unitary.

The purpose of this note is to provide a possible answer to this question. Rather than the radical modification of quantum mechanics required for pure states to evolve into mixed states, we adopt a more mild modification. We propose that at the black hole singularity one needs to impose a unique final state boundary condition.

More precisely, we have a unique final wavefunction for the interior of the black hole. Here we are putting a final state boundary condition on part of the system, the interior of the black hole. This final boundary condition makes sure that no information is “absorbed” by the singularity.
Full pdf @ hep-th 0310/0310281
_______________________________________________________
_______________________________________________________

Dimensions 4

_______________________________________
Image from Wikipedia: warning this image may be copyrighted.
Philosophy Science Physics Technorati tags

The question was actually intended to be, read as, or mean:

Does string theory: Lisa Randall & Lubos et al, think these subatomic forces and fields will be encountered (exist?) in the greater cosmos. ie: will space ships encounter and be affected by relatively speaking 'giant' strings & gravitons the size of galaxies and planets, - see angle and perspective of galaxy pic below - in these other 'dimensions' currently invisible to us in outer space - which is where some people's thinking and current thought is leading.

Dimensions (3+1): height, length, width + Time.

Three dimensions are all we see -- how could there be any more? Einstein's general theory of relativity tells us that space can expand, contract, and bend. If one direction were to contract down to an extremely tiny size, much smaller than an atom, it would be hidden from our view. If we could see on small enough scales, that hidden dimension might become visible.

See Plato for dimensional-referencing

At the very least, quantum gravity ought to describe physics on the smallest possible scales. Easy to find with dimensional analysis: Build a quantity with the dimensions of length using the speed of light, Planck's constant, and Newton's constant. Whether quantum gravity will yield a revolutionary shift in quantum theory, general relativity, or both remains to be seen.
_________________________________________




Are experiments in a collider or accelerator really representative of Nature & the lanscape in the big dark expanse of the cosmos or the known Universe.

Or are they more representative of the cosmos and the known Universe or the 'physical' reality - in the same way that films, animations and video games are representative of life outside in the real world?

_____________________________________________
Quantum gravity is the field devoted to finding the microstructure of spacetime. Is space continuous? Does spacetime geometry make sense near the initial singularity? Deep inside a black hole? These are the sort of questions a theory of quantum gravity is expected to answer. The root of our search for the theory is an exploration of the quantum foundations of spacetime.

Do black holes exist? - do they lead to other universes?
Or are black holes matter where the mass of Sun or Star are compressed to the size of an ultra high density marblesized small sphere with the gravitational (magnetic?) field of the previous 'visible' Sun or Star.

Does information pass through a blackhole? - if not even light can escape a blackhole, then what information can possibly escape a blackhole?

Are we being metaphysical? - what goes past at death from the physical world to the Spirit world: memories, emotions, feelings? Preferences in tastes: music, fashion, flavours, smells ...

Picture credit: STSci & Hubble Heritage
_______________________________________________________
_______________________________________________________

Dimensions 3

_______________________________________
Image from Wikipedia: warning this image may be copyrighted.
Philosophy Science Physics Technorati tags


Superstring theory stipulates ten dimensions.
The world around us appears to contain only four (including time).
Something needs to be done about the superfluous six. -
from Lisa Randall's "Warped Passages"

Because you may have 10 Dimensions at subatomic level, does it mean you 'must' have 10 dimensions in the 'physical' world around us
Q [Homepage] 06.29.06 - 3:27 pm #


If they are at the subatomic level they are still in the world around us, but we just can't detect them unequivocally yet with traditional science.
Rae Ann [Homepage] 06.29.06 - 5:14 pm #


These dimensions are very small-- think of a long cylinder(100m) with radius of say 2mm. If you look at it from far away, say 1 km, you will see a long line with no thickness.

But if you get close enough you will see the 2mm thickness.

Similarly to see the very small compactified dimensions you need a really powerful "microscope" (accelerator or something that produces very high energies).
Think of uncertainty principle for a better understanding-- the smaller length resolution you want, higher the momentum (energy) required.

Our everyday world is at an energy scale where these tiny lengths will simply not be "visible". This was a very handwaving analogy-- but this is roughly why we do not "see" these extra dimensions.

There is this completely wrong notion that somehow string theorists simply decided to throw in these extra dimensions-- they are in fact rather tightly controlled by the maths required to implement a physical condition which is necessary for any quantum theory to make sense.
I apologize to the experts who can certainly explain this much better than me, and perhaps manage to be more technically precise.
AR [Homepage] 06.29.06 - 9:14 pm #

"Regarding the Superfluous Six": Since Lubos is on a much-needed long-overdue hiatus, I will officially declare that it is "Amateur Night at The Reference Frame". Moreover, I will boldly volunteer to be the second amateur to take a mediocre stab at Q's thought-provoking question. Let me begin my figurative stabbing...

If one wants to conceptualize "the superfluous six", then one must gain a grasp of brane/bulk cosmology... First imagine dividing the cosmos into a higher dimensional bulk space and a lower dimensional brane space. Next imagine dividing strings into two distinct favors:

(1) open strings and
(2) closed strings.

As a general rule, non-graviton-particles act as open strings and are strictly confined to the lower dimensional brane(s).
By contrast, gravitons act exclusively as closed strings and uniquely behave as cosmic interlopers between the higher dimensional bulk and the lower dimensional brane(s).

Consequently, gravity is the only force in nature which is qualified to travel to-and-fro between the higher and lower dimensions. In addition, it is conjectured that supersymmetry partners exist upon a separate brane which runs parallel to a companion brane.

The closed-loop strings of gravity act as a mediator between these two branes.

Furthermore, gravitons have the potential to display two distinct modes of behavior:
(1) the gravitons - which run perpendicular to the brane - have the capacity to polarize the brane. This polarization leads to gravitational leakage into the bulk.
(2) the gravitons - which run parallel to the brane - lack the capacity to polarize the brane. Non-polarization maintains gravitational sequestration of the brane.

In conclusion: the most reasonable way to make sense of gravity in the universe is to view the universe as containing more than 3+1 dimensions. Best Wishes!
Cynthia [Homepage] 06.30.06 - 12:11 am #

Three dimensions are all we see -- how could there be any more? Einstein's general theory of relativity tells us that space can expand, contract, and bend. If one direction were to contract down to an extremely tiny size, much smaller than an atom, it would be hidden from our view. If we could see on small enough scales, that hidden dimension might become visible.

See Plato for dimensional-referencing
_______________________________________________________
_______________________________________________________

Hidden Dimensions

Extra dimensions of space may be present in our universe. Their discovery would dramatically change our view of the cosmos and would prompt many questions.
How do they hide? What is their shape? How many are there? How big are they? Do particles and forces feel their presence?

Joanne Hewett
2006 slac lectures stanford.edu



In this Universe, we are still confronted with sometimes conflicting theories pulling in opposing directions, presenting different cosmoligical views or perceptions of the formation and origins or age of the Universe which surrounds us.

The Universe we live in
A constant and constantly evolving Universe.
We have some earth-shaking moments and events coming up at colliders or accelerators, which hope to demonstrate or reveal further evidence of the cosmological past of our universe, prove or disprove a big bang, and reveal the exciting possibility of extra dimensions in the space/time continuum.

An expanding universe, well hmmm... maybe we should use the term continuously evolving otherwise known in the trade as expanding Universe.

Supernova Acceleration Probes video animation SNAP
Supernova Acceleration Probes are to be sent to supernovae searching for evidence of an expanding universe which is flat and accelerating, ...
The discovery by the Supernova Cosmology Project (SCP) and the High-Z Supernova team that the expansion of the universe is accelerating poses an exciting mystery — for if the universe were governed by gravitational attraction, its rate of expansion would be slowing.
Acceleration requires a strange dark energy opposing this gravity. Is this Einstein’s cosmological constant, or more exotic new physics? Whatever the explanation, it will lead to new discoveries in astrophysics, particle physics, and gravitation.

Observations of exploding stars called Type Ia supernovae use them as markers of the expansion, of the growth of the universe as a function of time. Variations in the growth of distances reveal a picture of the cosmic environment, and so the pull of dark energy, in the way that the width of tree ring growth indicates the Earth's climatic environment over time. Combined with other astrophysical measurements, supernovae imply that more than two-thirds of our universe must be this dark energy.

well hmmm... perhaps the word constant for neither expanding or contracting, and not deccelerating would better describe what is meant by accelerating.

Blackholes and 'holes' in the spacetime fabric, are words which have already been used by others, words often with a different meaning. Can be so confusing or misleading.

Blackholes or Stars gone Supernova, where there is no longer a sizeable Sun and orbiting planets, possibly have a 'singularity' with the same gravitational pull as a Sun or Star, which one must skirt around so as not to be sucked into. This is what a blackhole could turn out to be, and which therefore is not a 'hole' but more likely an empty space in Space with a 'centre' which has the same gravitational pull as if a visible Sun or Star were still there.

Except it no longer is a Star or Sun, all that remains in that section/sector of space is possibly a 'singularity' with the mass and compressed density of the previous Sun or Star.
______________________________________________________
For intergalactic video animation visit: hubblesite blackholes

For update on the Shaw Prize for the accelerating universe
please visit: Saul Perlmutter, Adam Riess, Brian Schmidt ,
and Sean Carroll @ cosmicvariance
______________________________________________________
______________________________________________________
For more on extra dimensions and strings
please read Warped Passages by Lisa Randall
______________________________________________________
______________________________________________________