Three Roads To Quantum Gravity

144 THREE ROADS TO QUANTUM GRAVITY
is that the effects accumulate when a photon travels very long
distances. And we can detect photons that have travelled
across large fractions of the observable universe. He proposes
that by carefully studying images taken by satellites of very
violent events such as those that create X-ray and gamma-ray
bursts, it may be possible to discover experimentally the
discrete structure of space.
FIGURE 32
Computer model of a quantum spacetime, showing a universe with one
space and one time dimension. The structures shown exist on scales of 10 733
of a centimetre and 10 743 of a second. We see that the quantum geometry
¯uctuates very strongly because of the uncertainty principle. As with the
position of an electron in an atom, for such small universes the quantum
¯uctuations in the size of the universe are very important as they are as large
as the universe itself. [These simulations are the work of Jan Ambùjrn,
Kostas Anagnastopoulos and Renate Loll. They can be seen at their Web
page, http://www.nbi.dk/~konstant/homepage/lqg2/.]