Fuzziness on the road to physics' grand unification theory

October 6, 2008
UO physics doctoral student David Reeb and Stephen Hsu, professor of physics and member of the UO Institute of Theoretical Science. Credit: Photo by Jim Barlow

Leave it to hypothesized gravity to weigh down what physicists have thought for 30 years. If theoretical physicists, led by the University of Oregon's Stephen Hsu, are right, the idea that nature's forces merge under grand unification has grown fuzzy.

At issue are grand unified theories that first appeared in the 1970s. They have suggested that, at short distances or high-energy scales, electromagnetic forces, strong forces, which bind quarks in protons and neutrons, and weak forces, which drive nuclear decay, will coalesce into a single unified field. Indications of this idea could appear at the Large Hadron Collider (LHC).

Hsu and colleagues applied advanced computations to qualities that might exist in quantum gravity in distance-shortened, high-energy interactions. Working with Hsu on the project, to be described in the journal Physical Review Letters, were UO doctoral student David Reeb and Xavier Calmet, a former postdoc in the UO's Institute of Theoretical Science and now of the Center for Particle Physics and Phenomenology at Catholic University of Louvain in Belgium.

"The energy scale at which these three forces become equivalent is probably very high," Hsu said. "We do not have a direct way to probe what happens. We cannot actually produce the energies or produce the particles necessary to directly test whether unification occurs, so we look for hints at lower energy scales -- and look at how the interactions change. We have seen indications that these three interactions are starting to unify. If you extrapolate these trends to very high energy, it looks like, in certain models or theories, they could unify -- all based on experimental data. If grand unification exists, it might be shown at the LHC."

Enter quantum gravity. It's not the physical law version as seen under of Isaac Newton's apple tree but rather a physical theory about gravitational interactions of matter and energy that may be vital to grand unification. This is the realm of space time and its curvature. Hsu's team looked closely at quantum gravity and the interactions of the forces at work using extrapolations built by mathematical magnification.

"It is believed that at short distances and high energies the actual structure of space time will start to exhibit quantum fluctuations," Hsu said. "So there would be fuzziness in the nature of space and time. The scale at which this grand unification might occur is getting kind of close to the scale where quantum gravity might exhibit this kind of fuzziness."

The fuzziness, researchers theorize, blurs the envisioned highway to unification. The blurring, they say, is brought about in the interplay of nature's forces, where, in certain models of unification, there may be thousands of yet-unseen particles at the boundary, affecting the highway itself.

"The interplay of these forces, in our theory, creates more uncertainty than people previously though could exist in this whole discussion," said Reeb, who performed much of the number crunching. "It's an important result, because it is telling people that when you look at the low-energy data and you extrapolate them you may have to be much more careful than was thought."

If grand unification is to be found, the discovery would move particle physicist closer to the proposed idea of supersymmetry, whereby particles at each level have corresponding qualities in another level as they spin. "Our research says there are more uncertainties to this argument than previously believed," Reeb said.

The bottom line, Hsu said, is that as data is generated in the LHC, interpretations as to relationships to grand unification may be more difficult for particle physicists to pin down.

Source: University of Oregon

Explore further: 'Crucial steps towards comprehensive theory on the forces of nature'

Related Stories

Nuclear puzzle may be clue to fifth force

August 17, 2016

In a new paper, University of California, Riverside theoretical physicist Flip Tanedo and his collaborators have made new progress towards unravelling a mystery in the beryllium nucleus that may be evidence for a fifth force ...

The mysterious missing magnetic monopole

August 9, 2016

You've probably heard of the Higgs boson. This elusive particle was predicted to exist long ago and helped explain why the universe works the way it does, but it took decades for us to detect.

The 2004 Nobel Prize in Physics

October 5, 2004

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2004 "for the discovery of asymptotic freedom in the theory of the strong interaction" jointly to David J. Gross Kavli Institute for ...

End of an era at HERA accelerator

July 2, 2007

Fifteen years of scientific discovery came to an end on June 30th when the electrons and protons in the HERA accelerator made their final lap of the 6.3 km ring. The HERA ring has provided these particles and their anti-particle ...

Is Everything Made of Mini Black Holes?

May 18, 2009

(PhysOrg.com) -- In trying to understand how gravity behaves on the quantum scale, physicists have developed a model that has an interesting implication: mini black holes could be everywhere, and all particles might be made ...

Recommended for you

Physicist develops drip-free wine bottle

March 23, 2017

Drips are the bane of every wine drinker's existence. He or she uncorks a bottle of wine, tips it toward the glass, and a drop, or even a stream, runs down the side of the bottle. Sure, you could do what sommeliers in restaurants ...

Scientists evade the Heisenberg uncertainty principle

March 22, 2017

ICFO Researchers report the discovery of a new technique that could drastically improve the sensitivity of instruments such as magnetic resonance imagers (MRIs) and atomic clocks. The study, published in Nature, reports a ...


Adjust slider to filter visible comments by rank

Display comments: newest first

3.4 / 5 (5) Oct 06, 2008
Coulda, woulda, shoulda. Quit the hype. Details about true results rather than speculation, please.
3.3 / 5 (3) Oct 06, 2008
"to be described in the journal Physical Review Letters"

Bob, all the info in the world wont help if you cant absorb what u read. Besides, there is plenty of food for thought here!
2.5 / 5 (2) Oct 06, 2008
Quantum fluctuations, or extra dimensions?
4.5 / 5 (2) Oct 06, 2008
"interpretations as to relationships to grand unification"

Says it pretty clearly!!!! Grand fantasy!!
4.5 / 5 (2) Oct 07, 2008
It's theory. People are hoping for experiential data of the Higgs Boson, exotic energy, and ripples from closed loop strings.

They are merely fine-tuning their math so they can count for all permutations and variables so they don't miss it if it crops up.
4.3 / 5 (3) Oct 07, 2008
What am I reading here that I haven't read hundreds of times before?
5 / 5 (1) Oct 07, 2008
Quantum fluctuations, or extra dimensions?

Or Both?
Oct 12, 2008
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.