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17

millions or even billions of years across the universe, the tiny effects of

atomic spacetime become ampliﬁed to the point where observations

can detect them. While no spacetime atomic effects have yet been

observed, there is optimism that current and emerging technology will

have the required sensitivity to do so in the near future.

CAN

OTHER

DISCIPLINES

HELP

SOLVE

THE

PUZZLES

OF

QUANTUM

GRAVITY

?

Perimeter members have also found new ways to address questions

of quantum gravity by adopting and adapting methods from other

ﬁelds, including condensed matter physics and quantum computing.

This has led them to an approach called “quantum graphity,” which is

providing new tools to understand how physical laws and phenomena

like gravity emerge as a result of the speciﬁc geometry of spacetime.

Last year, Faculty members Laurent Freidel and Lee Smolin developed

an entirely new physics principle, known as the Principle of Relative

Locality. This innovation was the result of a collaboration with visiting

researchers Giovanni Amelino-Camelia and Jerzy Kowalski-Glikman.

Relative locality deepens Einstein’s relativity principle by theorizing

that each observer constructs a unique version of spacetime

that is dependent on his or her point of observation. According to

this principle, different universes may also be constructed from

observations using light of different wavelengths. In related work,

Freidel and Smolin also showed how to test this new hypothesis

experimentally using observations of gamma ray bursts.

WHAT

IF

SIZE

REALLY

DOESN

’

T

MATTER

?

Another remarkable development was the discovery of a new

formulation of Einstein’s general theory of relativity called Shape

Dynamics. One of the basic results of the general theory concerns the

relativity of simultaneity. This says that the notion of what is happening

“right now” at a distant location depends on the observer. Shape

Dynamics reveals that there is in general relativity a preferred notion of

time and simultaneity, which is determined by the motions of matter

all over the universe. When this is taken into account, the equations

of general relativity have a new property, which is that the size of

objects no longer has meaning – all that is measurable is shapes.

This remarkable insight was the result of a collaboration of young

theorists: PhD student Sean Gryb and Postdoctoral Researcher Tim

Koslowski, together with visiting PhD student Henrique Gomes.

References:

G. Amelino-Camelia, L. Freidel, J. Kowalski-Glikman, and L. Smolin, “The principle of relative locality,”

Phys. Rev. D. 84, 084010 (2011), arXiv:1101.0931.

L. Freidel and L. Smolin, “Gamma ray burst delay times probe the geometry of momentum space,”

arXiv:1103.5626.

H. Gomes, S. Gryb, and T. Koslowski, “Einstein gravity as a 3D conformally invariant theory,” Class.

Quant. Grav. 28, 045005 (2011), arXiv:1010.2481.

H. Gomes, S. Gryb, T. Koslowski, and F. Mercati, “The gravity/CFT correspondence,” arXiv:1105.0938.

FACULTY

Latham Boyle

Freddy Cachazo

Laurent Freidel

Jaume Gomis

Daniel Gottesman

Lucien Hardy

Fotini Markopoulou

Robert Myers

Philip Schuster

Lee Smolin

Robert Spekkens

Natalia Toro

Neil Turok

Guifre Vidal

Pedro Vieira

Faculty member

Laurent Freidel