(PhysOrg.com) -- Several speculative theories in physics involve extra dimensions beyond our well-known four (which are broken down into three dimensions of space and one of time). Some theories have suggested 5, 10, 26, or more, with the extra spatial dimensions "hiding" within our observable three dimensions. One thing that all of these extra dimensions have in common is that none has ever been experimentally detected; they are all mathematical predictions.

More recently, physicists have been theorizing the possibility of lower dimensionality, in which the universe has only two or even one spatial dimension(s), along with one dimension of time. The theories suggest that the lower dimensions occurred in the past when the universe was much smaller and had a much higher energy level (and temperature) than today. Further, it appears that the concept of lower dimensions may already have some experimental evidence in cosmic ray observations.

Now in a new study, physicists Jonas Mureika from Loyola Marymount University in Los Angeles, California, and Dejan Stojkovic from SUNY at Buffalo in Buffalo, New York, have proposed a new and independent method for experimentally detecting lower dimensions. They’ve published their study in a recent issue of *Physical Review Letters*.

In 2010, a team of physicists including Stojkovic proposed a lower-dimensional framework in which spacetime is fundamentally a (1 + 1)-dimensional universe (meaning it contains one spatial dimension and one time dimension). In other words, the universe is a straight line that is “wrapped up” in such a way so that it appears (3 + 1)-dimensional at today’s higher energy scales, which is what we see.

The scientists don’t know the exact energy levels (or the exact age of the universe) when the transitions between dimensions occurred. However, they think that the universe’s energy level and size directly determine its number of dimensions, and that the number of dimensions evolves over time as the energy and size change. They predict that the transition from a (1 + 1)- to a (2 + 1)-dimensional universe happened when the temperature of the universe was about 100 TeV (teraelectronvolts) or less, and the transition from a (2 + 1)- to a (3 + 1)-dimensional universe happened later at about 1 TeV. Today, the temperature of the universe is about 10^{-3} eV.

So far, there may already be one piece of experimental evidence for the existence of a lower-dimensional structure at a higher energy scale. When observing families of cosmic ray particles in space, scientists found that, at energies higher than 1 TeV, the main energy fluxes appear to align in a two-dimensional plane. This means that, above a certain energy level, particles propagate in two dimensions rather than three dimensions.

In the current study, Mureika and Stojkovic have proposed a second test for lower dimensions that would provide independent evidence for their existence. The test is based on the assumption that a (2 + 1)-dimensional spacetime, which is a flat plane, has no gravitational degrees of freedom. This means that gravity waves and gravitons cannot have been produced during this epoch. So the physicists suggest that a future gravitational wave detector looking deep into space might find that primordial gravity waves cannot be produced beyond a certain frequency, and this frequency would represent the transition between dimensions. Looking backwards, it would appear that one of our spatial dimensions has “vanished.”

The scientists added that it should be possible, though perhaps more difficult, to test for the existence of (1 + 1)-dimensional spacetime.

“It will be challenging with the current experiments,” Stojkovic told *PhysOrg.com*. “But it is within the reach of both the LHC and cosmic ray experiments if the two-dimensional to one-dimensional crossover scale is 10 TeV.”

Lower dimensions at higher energies could have several advantages for cosmologists. For instance, models of quantum gravity in (2 + 1) and (1 + 1) dimensions could overcome some of the problems that plague quantum gravity theories in (3 + 1) dimensions. Also, reducing the dimensions of spacetime might solve the cosmological constant problem, which is that the cosmological constant is fine-tuned to fit observations and does not match theoretical calculations. A solution may lie in the existence of energy that is currently hiding between two folds of our (3 + 1)-dimensional spacetime, which will open up into (4 + 1)-dimensional spacetime in the future when the universe’s decreasing energy level reaches another transition point.

“A change of paradigm,” Stojkovic said about the significance of lower dimensions. “It is a new avenue to attack long-standing problems in physics.”

**Explore further:**
Who cares about the fourth dimension?

**More information:**
Jonas Mureika and Dejan Stojkovic. “Detecting Vanishing Dimensions via Primordial Gravitational Wave Astronomy.” *Physical Review Letters* 106, 101101 (2011). DOI: 10.1103/PhysRevLett.106.101101

## Kyleric

## Feedhorn

Sounds a lot like Multi-Space Physics that I invented but never published. In MSP the definition of space is affected by size. Neutron-Space, Atom-Space, STEM-Space, and Our-Space. Are 0,1,2,3Dimensions.

## WxWizard

Our dimension is defined by gravity. Subatomic particles operate in a dimension defined predominately by the strong and weak forces.

Sooo... What other yet to be discovered forces would create the framework for these other dimensions to exist?

## kaasinees

## SincerelyTwo

Being able to deform a circle in to a box doesn't make them equal. Boxes have properties that circles don't have. Maybe you don't understand the concept of equality.

What is it with you guys, ridiculously inane statements back to back.

I better stop replying, I'm just getting frustrating being forced to experience this insanity.

## kaasinees

Thinking of time as a dimension is not insane?

## Skeptic_Heretic

Word salad anyone?

## Quantum_Conundrum

However, the machine operating on this one-dimensional array is actually a 3-dimensional machine, and the memory locations storing this one-dimensional array are actually 3-dimensional cells.

You cna't actually do "work" on a one-dimensional array without access to other dimensions through which to move "information".

## kaasinees

## Skeptic_Heretic

Time is a dimension as it is the progression through which the other 3 dimensions are measured.

You're not talking about dimensions, you're talking about fields and scopes of effect.

## Skultch

What do you care? You are not even a man with your pre-pubes yet. ;p The smartest people here are also the most modest about their knowledge and abilities. This is a forum for laypeople, and most of us act accordingly.

This topic got crazy, and quick.

## mfytq

## TabulaMentis

Lisa Zyga knows a good story when she sees one!

## Birthmark

I know these postings have been crazy (and here I go!) but the subject of many dimensions brings up a lot of questions and possible theories.

--But could there be life in other dimensions?

## Pyle

Anyway,

Enough talk of extra dimensions. The idea that originally there were fewer dimensions and that as the universe cools more develop seems counterintuitive to me, so they must be on to something.

Sounds like they fit the timing of their dimensional expansion to inflation and the next step from 3+1 to 4+1 to DE behavior? This one is a real mind bender. Neat idea.

## TabulaMentis

## Gawad

## TabulaMentis

Mar 18, 2011## Deadbolt

## MorganW

Are these transistions they speak of similar to "Phase changes" I've heard of previously? Would such a transition be likely to occur instantaneously across the entire universe, or would it appear to occur over time (to an observer)?

## Gawad

## Burnerjack

Sounds like something that happens when you give full tenure and a hit of acid to a group of theorists....

## Pyle

I imagine that the transition from a 2+1 to 3+1 could explain our inflationary period as well as flatness.

TM: SH was right, WxWizard's comment was very confused, misusing the term dimensions. Birthmark's comment is just fantasy thinking, which in my eyes is perfectly acceptable if not taken too seriously without further reality based development.

## Skeptic_Heretic

The mathematics behind the potential for creating a universe in a particle accelerator are incredibly interesting. As the created Universe increased in interior dimension, the mathematics show that it would appear to be decreasing in physical dimension from a perspective outside of that universe.

## Gawad

## baudrunner

## Skeptic_Heretic

You need a better yardstick.

## Pyle

Every engineer and scientist on the face of the planet disagrees with the tenor of this statement. Math is a powerful tool that we use everyday to predict reality. Yes, it can show the impossible, but that is usually a result of flawed application or exceeding the predictive capacity of a theory.

## Ricochet

Mar 18, 2011## OdinsAcolyte

Now lets parallel it with other possible realities.

Our universe is a leaf on a branch. We don't even know where the leaf or branch sits.

Anyway it is fun to think about and in the end it matters not in the least. Reality is particulate and fleeting.

Merrily! Merrily! Merrily! Merrily! Life is but a dream!

## TabulaMentis

## jselin

On a related note, this reminds me of the book "A Wrinkle in Time"

## beelize54

## SpikeTheHuman

## ubavontuba

## LLove

## Moebius

I think there is only one dimension (where any point in it can be described by 3 coordinates) and time which isn't one. My theory from way back. Sounds like they are getting closer to agreeing with me, now all they have to do is figure out what time really is instead of what they now think it is.

I honestly hope there are lots of dimensions, the stranger the universe is the better I like it.

## RobertKarlStonjek

It is good to see science moving away from the just-so stories like string theory and toward hypotheses that can actually be tested.

Good riddance to the faith based models such as creationism, SUSY and Dark Energy.

BTW the two models, both equally implausible, that involve versions of wriggly things that nobody has ever seen are String theories and the Australian Aboriginal's Dream Time story of the great rainbow snake that created the universe...time to move on from myth based cosmologies...

## TabulaMentis

## beelize54

## beelize54

## TabulaMentis

I love all three and would not be here if there was not a connection.

So people over in Australia have seen that serpent too. Very interesting!!!

## stvnwlsn

## rwinners

Well said. Didya know that most of the scientific discoveries ever made were made in the lab, not the mathematics classroom.

## mjesfahani

## mjesfahani

http://en.wikiped.../Tachyon

## rwinners

## TabulaMentis

Maybe for you.

## soulman

So you totally comprehend the universe?

## TabulaMentis

## soulman

You really are deluded if you think you've got the universe mostly figured out. And even more so if you think that I could possibly share the same stage with the likes of Ed Witten and Brian Greene!

## beelize54

## beelize54

## Alex_Reynolds

## Alex_Reynolds

## Alex_Reynolds

SH, this would actually take on the structure of a multilayered fractal as viewed from the outside, one that eventually "winked" out of existence (as seen from the "outside") as it appeared to grow smaller.

## Rohitasch

Which plane is this?

## nothingness

## Martin_Shaw

Mar 19, 2011## soulman

Mar 19, 2011## Caliban

## X24

huh, so one should, please, imagine an inverse-loop transdimensional destabilizer/converger/converter/generator/harmony-drive as being more than "just" Science Fiction...

## GreyLensman

Amen to that mate. There is so much B/S in the forums - it'd be better if they were disabled.

## Bill_Zimmerly

---

Yet - BECAUSE WE HAVE RANDOM ACCESS TO ANY BYTE - we can make it seem to be "N"-dimensional in usage.

## Blakut

## ruebi

## Ron_Alford

## rwinners

## noodler

At some radius beneath the event horizon it's 2D; at a smaller radius, it's 1D; and at the center, it's 0D?

ribbonification instead of spaghettification--or does 2D ribbonification become linification?

Does the question of the mechanism of gravity propagation out of the event horizon become even more problematic under this theory?

Fascinating stuff!

## JPK69

## Squeezle42

Could the universe/dimensions of reality, also be folding in such ways to pass information between these folds better? Makes me wonder what the surface are of the human brain actually is when completely unfolded... Anyone have an answer to that?

Edit: Looks like approx 2500cm squared

## SteveL

And it'll be quite cold, so dress warmly.

## slash

That's an interesting thought. Length contraction based on the laws of special relativity do cause one dimension of an object to diminish when accelerated to close to the speed of light. If it weren't for the mathematical singularity in these equations, you could think that at some point that one dimension would vanish, reducing the object to just two dimensions. It would require a modification of Einsteins formulas though, something that would only add a meaningful component at energies approaching the TV range ...

## TabulaMentis

I wonder how much gravity there is in the center of earth compared to the surface of our planet?

## Thraxzer

## TabulaMentis

## Alex_Reynolds

## Pyle

Just a guess though.

## vacuum-mechanics

## Critic

1)A 2+1 space-time (two spatial dimensions and one time dimension)does not allow gravitational waves to exist. This means that gravitational field cannot be transmitted in 2+1 dimensions and simply vanishes. This is in flagrant contradiction with cosmological models of the early Universe and the known fact that gravity becomes increasingly strong at short distances.

2) Likewise, free electromagnetic (EM) waves cannot exist in 2+1 dimensions. Free EM fields are transverse with the electric (E) and magnetic (H) vectors orthogonal to each other and to the direction of propagation. In 2+1 dimensions, E and H are orthogonal but the direction of propagation is simply non existent.

3) General Relativity is a low-energy (effective) field theory of gravity valid for large distances and there is no indication whatsoever that it remains valid in the quantum realm.

Ervin Goldfain

## Thraxzer

## ab3a

Uh, no. An incomprehensible theory is not interesting. Something you understand and can see the implications of is interesting. This is the attitude that begat the Emperor's New Clothes.

## freeluck

## josetphy

My basic questions (which I haven't found in the original paper), are:

1. Does the ~100TeV crossover correspond to the Big-Bang itself (and nor "shortly after", as stated in this article);

and,

2. Does the next crossover (~1TeV) correspond to the beginning of the inflationary period?

and,

3. Since the last crossover is roughly an order of magnitude lower than the first, and, since the actual temperature is about 10^-3 eV (which is far from an order of magnitude lower than the last), is there the a [calculate