### NOTES

[1]C. J. Isham, Canonical Quantum Gravity and the Problem of Time, Imperial College preprint, gr-qc/9210011, /TP/91-92/25.

[2]K. V. Kuchar, {\it Time and interpretations of quantum gravity] in the {\it Proceedings of the 4th Canadian Conference on General Relativity and Relativistic Astrophysics], eds. G. Kunstatter, D. Vincent and J. Williams (World Scientific, Singapore,1992).

[3]C. Rovelli, Phys. Rev. D 42 (1991) 2638; 43 (1991) 442; in {\it Conceptual Problems of Quantum Gravity] ed. A. Ashtekar and J. Stachel, (Birkhauser,Boston,1991); Class. Quantum Grav. 8 (1991) 317-331.

[4]L. Smolin {\it Space and time in the quantum universe] in the proceedings of the Osgood Hill conference on {\it Conceptual Problems in Quantum Gravity] ed. A. Ashtekar and J. Stachel, (Birkhauser,Boston,1991); {\it Time, structure and evolution in cosmology], preprint, submitted to the British Journal for the Philosophy of Science; {\it Time, measurement and information loss in quantum cosmology] gr-qc/9301016 in the Brill Feschrift, ed. Hu and Jacobson, Cambridge University Press, 1994.

[5]J. B. Barbour,to appear in the {\it Procedings of the NATO Meeting on the Physical Origins of Time Asymmetry] eds. J. J. Halliwell, J. Perez-Mercader and W. H. Zurek (CAmbridge University Press, Cambridge, 1992); {\it On the origin of structure in the universe] in {\it Proc. of the Third Workshop on Physical and Philosophical Aspects of our Understanding of Space and Time] ed. I. O. Stamatescu (Klett Cotta); {\it Time and the interpretation of quantum gravity] Syracuse University Preprint, April 1992.

[6]L. Smolin, {\it The Life of the Cosmos] Oxford University Press, New York and Weidenfeld and Nicolson, London, (1997).

[7]S. Kauffman, {\it Investigations on the character of autonomous agents and the worlds they mutually create] Santa Fe Institute preprint, 1996.

[8]S. Kauffman, {\it Origins of Order] Oxford University Press; {\it At home in the universe], Oxford University Press, 1996.

[9]E. T. Newman and C. Rovelli, Physical Review Letters, (1992)

[10]C. Rovelli and L. Smolin {\it Discreteness of area and volume in quantum gravity] Nuclear Physics B 442 (1995) 593. Erratum: Nucl. Phys. B 456 (1995) 734.

[11]C. Rovelli and L. Smolin, Spin networks and quantum gravity" gr-qc/9505006, Physical Review D 52 (1995) 5743-5759.

[12]J. B. Barbour, Nature 249 (1974) 328 Erattum: Nature 250 (1974) 606; Nuovo Cimento 26B (1975) 16; J.B. Barbour and B. Bertotti, Nouvo Cimento 38B (1977) 1.

[13]J.B. Barbour and B. Bertotti, Proc. Roy. Soc. Lond. A 382 (1982) 295.

[14]F. Markopoulou and L. Smolin, {\it Causal evolution of spin networks] gr-qc/9702025. CGPG 97/2-1.

[15]J. Hemion {\it Classification of knots in three dimensional space] Oxford University Press.

[16]R Penrose: in {\it Quantum theory and beyond] ed T Bastin, Cambridge U Press 1971; in {\it Advances in Twistor Theory], ed. L. P. Hughston and R. S. Ward, (Pitman,1979) p. 301; in {\it Combinatorial Mathematics and its Application] (ed. D. J. A. Welsh) (Academic Press,1971).

[17]L. Smolin, {\it The future of spin networks] gr-qc/9702030.

[18]J. Baez, Spin networks in gauge theory, Adv.\ Math.\ {\bf 117] (1996), 253-272, gr-qc/941107; Spin networks in nonperturbative quantum gravity, in {\sl The Interface of Knots and Physics], ed.\ Louis Kauffman, American Mathematical Society, Providence, Rhode Island, 1996, gr-qc/9504036.

[19]A. Ashtekar and C. J. Isham, Class and Quant Grav 9 (1992) 1069; A Ashtekar J Lewandowski D Marlof J Mour\~{a]u T Thiemann: Quantization of diffeomorphism invariant theories of connections with local degrees of freedom", gr-qc/9504018, JMP 36 (1995) 519; T. Thiemann, Quantum spin dynamics I, Harvard preprint (1996), gr-qc/9606089; Quantum spin dynamics II, Harvard preprint (1996), gr-qc/9606090; A. Ashtekar and J. Lewandowski, "Quantum Geometry I: area operator" gr-qc/9602046.

[19]J.B.~Hartle, {\it Unruly Topologies in Two Dimensional Quantum Gravity], Class. \& Quant. Grav., 2, 707, 198{5b]; R.~Geroch and J.B.~Hartle, {\it Computability and Physical Theories] Found. Phys., 16, 533, 1986. J.B.~Hartle, {\it Unruly Topologies in Two Dimensional Quantum Gravity], Class. \& Quant. Grav., 2, 707, 198{5b].

[20]M. Reisenberger, unpublished.

[21]M. Reisenberger and C. Rovelli, {\it Sum over Surfaces'' form of Loop Quantum Gravity], gr-qc/9612035.

[22]J. Baez, seminars, Penn State, February 1997.

[23]R. Doldan, R. Gambini and P. Mora, Int. J. of Theor. Phys. 35 (1996) 2057.

[24]L. Smolin, {\it Cosmology as a problem in critical phenomena] in the proceedings of the Guanajuato Conference on Complex systems and binary networks, (Springer,1995), eds. R. Lopez-Pena, R. Capovilla, R. Garcia-Pelayo, H. Waalebroeck and F. Zertuche. Gr-qc/9505022