Spiros Cotsakis

Professor of Mathematical Physics and Cosmology

University of the Aegean




It is legitimate for the mathematician to study all possible models, with arbitrary topology as well as arbitrary Lorentzian metric. It is still believed by the majority of physicists and astronomers that such a manifold does model the cosmos, and moreover its metric satisfies the Einstein equations, eventually in dimensions greater than four. This hypothesis opens a vast field of investigations, where remarkable conjectures have been proposed. Many results have been obtained, sometimes surprising, but many fundamental questions remain open.” Yvonne Choquet-Bruhat.

 

 Albert Einstein, foremost twentieth century scientist, once said: ``The most incomprehensible thing about the universe is that it is comprehensible’’. We may complement Einstein’s remark by adding: ``The most comprehensible thing about the Universe is that it is incomprehensible’’. A universe – any universe – is comprehensible because it has been shaped by the human mind. Whereas the Universe is incomprehensible if only because we can never grasp the entirety of a reality of which we are only a part or an aspect. The Universe may comprehend itself, but not by means of finite human minds.” Edward Harrison.

 

 

Education

First Degree: Mathematics, University of Athens, Greece 

M.Sc.: Astronomy, University of Sussex, UK

Ph.D.: Mathematical Physics and Cosmology, University of Sussex, UK

 

Research interests

General relativity, mathematical cosmology, differential geometry, dynamical systems, history and philosophy of relativity and cosmology.

 

Courses

I currently teach the following courses:

Mathematical Modelling

Dynamical Systems

 

Students

My current PhD students are:

Ø      George Kolionis (Gravitational entropy in modified gravity)

Ø      Demetrios Trahilis (Cauchy problem in f(R) theories of gravity)

Ø      Georgia Kittou (Asymptotics and singularities in scalar-tensor cosmologies)

Ø      Andreas Paraskevopoulos (Evolution of ideas about cyclic cosmologies)

Ø      Fotini Argiana (History of the Olbers paradox)

 

Undergraduate students

·         Vasilios Elefteropoulos (Archimedes and π)

·         Vivi Alikari (Variational and conformal structure of higher order and scalar-tensor theories)

 

Former PhD students of mine include:

Ø      Ifigeneia Klaoudatou (2002-2008)

Ø      John Miritzis (1994-1997)

 

§         Our group currently has two post doctoral fellows, Ifigeneia Klaoudatou and Antonios Tsokaros.

 

MG11

 

MG12

This will soon be a set of links to the parallel session on “Cosmological Singularities and Asymptotics” to be held in Paris next July at the Marcel Grossman Meeting.

 

Publications in Spires

 

Selected Recent publications

1.      Brane singularities and their avoidance.

Antoniadis, S. Cotsakis, I. Klaoudatou, Class. Quant. Grav., Vol. 27, pp. 235018, 2010.

2.      A General Sudden Cosmological Singularity.

J. D. Barrow, S. Cotsakis, A. Tsokaros, Class. Quant. Grav., Vol. 27, pp. 165017, 2010.

 

Selected Older publications

1.      Inflation and the Conformal Structure of Higher-Order Gravity Theories.

J. D. Barrow and S. Cotsakis, Phys. Lett. B214 (1988) 515–518

2.      Chaotic Behaviour in Higher-Order Gravity Theories.

J. D. Barrow and S. Cotsakis, Phys. Lett. B232 (1989) 172–17

3.      Self-Regenerating Inflationary universe in higher-order gravity in arbitrary dimension.

J. D. Barrow and S. Cotsakis, Phys. Lett. B258 (1991) 299–304

4.      Quiescent Self-Regenerating Universe.

S. Cotsakis, In Proceedings of the First Greek Astronomical Meeting, P. Laskarides, (ed.), (Athens, 1992), pp. 135-140

5.      Conformal Transformations Single Out a Unique Measure of Distance.

S. Cotsakis, Phys. Rev. D47 (1993) 1437-1439; Erratum: Phys. Rev. D49 (1994) 1145

6.      Mixmaster Universe in Fourth-Order Gravity Theories.

S. Cotsakis, J. Demaret, Y. de Rop and L. Querella, Phys. Rev. D48 (1993) 4595–4603

7.      Stability of FRW Cosmology in Higher Order Gravity.

S. Cotsakis and G. Flessas, Phys. Rev. D48 (1993) 3577–3584.

8.      Generalized No-Hair Theorems.

S. Cotsakis and G. Flessas, Phys. Lett. B319 (1993) 69–73.

9.      Painlev\'{e} Analysis of the Mixmaster Universe.

S. Cotsakis and P. G. L. Leach, J. Phys. A27 (1993) 1625–1631.

10.  Power-Law Inflation and Conformal Transformations.

S. Cotsakis and P. Saich, Class. Quant. Grav. 11 (1994) 383–387.

11.  Escape Rates for the Quiescent Self-Regenerating Universe.

S. Cotsakis, Phys. Lett. B328 (1994) 270–273.

12.  Minimally Coupled Scalar Field Wormholes.

S. Cotsakis, P. G. L. Leach and G. Flessas, Phys. Rev. D49 (1994) 6489–6492.

13.  Past-Instability Conjecture and Cosmological Attractors in Generalized Isotropic Universes.

S. Cotsakis and G. Flessas, Phys. Rev. D51 (1995) 4160–4168.

14.  Graviton Creation and Conformal Non Invariance in Higher Order Gravity Theories.

S. Cotsakis and G. Flessas, Phys. Rev. D52 (1995) 5783–5786.

15.  Reply to Two Comments by Teyssandier and by Schmidt.

S. Cotsakis, Phys. Rev. D52 (1995) 6199–6200.

16.  Non-Linear Lagrangians and the Isotropy of the Universe.

J. Miritzis and S. Cotsakis, Phys. Lett. B383 (1996) 377–382.

17.  Adiabatic Invariants and Mixmaster Catastrophes.

S. Cotsakis, R. Lemmer and P. G. L. Leach, Phys. Rev. D57 (1998) 4691–4698.

18.  Proof of the Cosmic No-Hair Conjecture for Some Quadratic Homogeneous Cosmologies.

S. Cotsakis and J. Miritzis, Class. Quant. Grav. 15 (1998) 2795–2801.

19.  Symmetries of homogeneous cosmologies.

S. Cotsakis, P.G.L. Leach and H. Pantazi, Grav. Cosm. 4 (1998) 314–325.

20.  Mathematical problems in higher order gravity and cosmology.

S. Cotsakis, In Proceedings of the Eighth Marcel Grossman Meeting on General Relativity, T. Piran and R. Ruffini, eds., (World Scientific, 1999), pp. 505–507.

21.  Variational and conformal structure of nonlinear metric-connection gravitational lagrangians.

S. Cotsakis, J. Miritzis and L. Querella, J. Math. Phys. 40 (1999) 3063–3071.

22.  Ever-Expanding, Isotropizing, Quadratic Cosmologies.

S. Cotsakis, G.P. Flessas, P.G.L. Leach and L. Querella, Grav. Cosm. 6 (2000) 282–290.

23.  Symmetries, Singularities and Integrability in Complex Dynamics IV: Painlev´e Integrability of Isotropic Cosmologies.

J. Miritzis, P.G.L. Leach and S. Cotsakis, Grav. Cosm. 6 (2000) 282-290.

24.  Symmetries, Singularities and Integrability in Complex Dynamics VI: Painlev´e Integrability of FRW-Scalar Cosmologies.

P.G.L. Leach, S. Cotsakis and J. Miritzis, Grav. Cosm. 7 (2001) 311–320.

25.  Symmetries, Singularities and Integrability in Nonlinear Mathematical Physics and Cosmology.

S. Cotsakis and P. G. L. Leach, In Proceedings of the Fourth International Conference on Symmetries in Nonlinear Mathematical Physics, Proc. Inst. Math. N.A.S. Ukraine

43 (2002) 128-135.

26.  Algebraic Integrability of FRW-Scalar Cosmologies.

S. Cotsakis and J. Miritzis, In Proceedings of the Ninth Marcel Grossman Meeting on General Relativity, V. Gurzadyan, R.T. Jantzen and R. Ruffini (eds.) (World Scientific,

2002) pp. 1943-1945.

27.  Scalar-Tensor \sigma-Cosmologies.

S. Cotsakis and J. Miritzis, In Proceedings of the Ninth Marcel Grossman Meeting on General Relativity, V. Gurzadyan, R.T. Jantzen and R. Ruffini (eds.) (World Scientific,

2002) pp. 1945-1947.

28.   Current Trends in Mathematical Cosmology.

S. Cotsakis, In Modern Theoretical and Observational Cosmology, S. Cotsakis and M. Plionis (eds.) (Kluwer, ASSL276, 2002), pp. 5–18.

29.   A Note on Wavemap-Tensor Cosmologies.

S. Cotsakis and J. Miritzis, In Modern Theoretical and Observational Cosmology, S. Cotsakis and M. Plionis (eds.), Kluwer, ASSL276, 2002, pp 67–74.

30.   Is Nature Generic?

S. Cotsakis and P. G. L. Leach, In Cosmological Crossroads, S. Cotsakis and E. Papantonopoulos (eds.), (Springer, LNP592, 2002), pp. 3–15.

31.  Cosmological Singularities.

S. Cotsakis, In Cosmological Crossroads, S. Cotsakis and E. Papantonopoulos (eds.), (Springer, LNP592, 2002), pp. 59–94.

32.  Global Hyperbolicity and Completeness.

Y. Choquet-Bruhat and S. Cotsakis, J. Geom. Phys. 43 (2002) 345–350.

33.  Completeness Theorems in General relativity.

Y. Choquet-Bruhat and S. Cotsakis, In Proceedings of the 10th Greek Relativity Conference, K. D. Kokkotas and N. Stergioulas (eds.) (World Scientific, 2003) pp. 145–149.

34.  Global Hyperbolicity of Sliced Spaces.

S. Cotsakis, Gen. Rel. Grav. 36 (2004) 1183–1188.

35.  Future Singularities of Isotropic Cosmologies.

S. Cotsakis and I. Klaoudatou, J. Geom. Phys. 55 (2005) 306–315.

36.  Modern Approaches to Cosmological Singularities.

S. Cotsakis and I. Klaoudatou, J .Phys. Conf. Ser. 8 (2005) 150.

37.  Slice Energy and Theories of Gravitation.

S. Cotsakis, J. Phys. Conf. Ser.8 (2005) 39-48.

38.  Singular Isotropic Cosmologies and Bel-Robinson Energy.

S. Cotsakis and I. Klaoudatou, In the Proceedings of the A. Einstein Century International Conference, Paris, France, July 18-22, 2005.

39.  Cosmological Singularities and Bel-Robinson Energy.

S. Cotsakis and I. Klaoudatou, J. Geom. Phys. 57 (2007) 1303-1312

40.  Future Singularities and Completeness in Cosmology.

S. Cotsakis, In the Proceedings of the Thessaloniki Meeting on Cosmology and Gravitational Physics, Thessaloniki, December 2005, Greece.

41.  The Dominant Balance at Cosmological Singularities.

S. Cotsakis and J. D. Barrow, J. Phys. Conf. Ser. 68 (2007) 012004

42.  Bel-Robinson energy and the nature of singularities in isotropic cosmologies.

I. Klaoudatou and S. Cotsakis, J. Phys. Conf. Ser. 68 (2007) 012010

43.  Singularities of varying light speed cosmologies.

J. Miritzis and S. Cotsakis, J. Phys. Conf. Ser. 68 (2007) 012019

44.  Asymptotics of flat, radiation universes in quadratic gravity.

S. Cotsakis, A. Tsokaros, Phys. Lett. B651 (2007) 341-344

45.  Slice energy in higher order gravity theories and conformal transformations

S. Cotsakis, Grav. Cosm. 14 (2008) 176-183

46.  Talking About Singularities

S. Cotsakis, In Proceedings of the MG11 Meeting, H. Kleinert, R. J. Jantzen and R. Ruffini, (World Scientific, 2008), pp. 758-68

47.  Braneworld cosmological singularities

I. Antoniadis, S. Cotsakis, I. Klaoudatou,  In Proceedings of the MG11 Meeting, H. Kleinert, R. J. Jantzen and R. Ruffini, (World Scientific, 2008), pp. 2054-6

48.  Flat, radiation universes with quadratic corrections and asymptotic analysis

S. Cotsakis, A. Tsokaros, In Proceedings of the MG11 Meeting, H. Kleinert, R. J. Jantzen and R. Ruffini, (World Scientific, 2008),  pp. 2045-7

 

 

Last modified: May 24, 2011