Understanding the origins of the Universe and how it works and evolves is the present mission of a large community of physicists. It calls for a large scale vision, involving general relativity, astrophysics, and cosmology. Theoretical physics is presently at an important moment in its history. As predicted by Einstein, gravitational waves have been experimentally proven to exist. With the discovery of the Higgs boson, the set of interactions and elementary particles that is called the "standard model" (SM), is complete. Yet the Higgs boson itself, and how it breaks the electroweak symmetry, remains a fascinating subject requiring further studies and verification. Furthermore, several experimental facts are not accounted for by the SM: (i) the baryon asymmetry of the Universe, (ii) the nature and origin of dark matter, and (iii) the origin of neutrino masses; these have no unique, if any, explanation in the SM and yet will require answers from particle physics. We need to explore further both SM and its extensions. This is a subject of papers included in this book, which gives representation to the topics discussed during the Matter to the Deepest conference in 2019 in Poland (http://indico.if.us.edu.pl/event/5).

The International Conference on Theoretical Physics, TH-2002, took place in Paris from July 22 to 27 in the Conference Center of the UNESCO, the United Nations Educational Scientific and Cultural Organization, under aegis of the IUPAP, the International Union of Pure and Applied Physics and of the French and Euro pean Physical Societies, with a large support of several French, European and international Institutions. International and crossdisciplinary, TH-2002 welcomed around 1200 partic ipants representing all domains of modern theoretical physics. The conference offered a high-level scientific program, including 18 plenary lectures, 45 general lectures in thematic sessions and 140 more specialized lectures, partly invited and partly selected among proposals received from participants. Around 500 contribu tions were also presented as posters. Plenary lectures as well as general thematic lectures were addressed to a general audience of theoricians, not only to specialists. According to our commitments towards UNESCO and other sponsoring insti tutions, TH-2002 attributed more than 200 fellowships, mostly to scientists from developing countries and Eastern Europe, covering registration fees and, for more than half of them, stay expenses with student type accomodation. Special highlights of the conference included • the opening ceremony on July 22, with the participation of Mrs Claudie Haignere, French Minister of Research, and M. Walter Erdelen, General Ad joint Director for Sciences at UNESCO. Their opening addresses were espe cially appreciated and are reproduced below. This ceremony preceded the first lecture by Professor Cohen-Tannoudji, Physics Nobel prize winner.

One of the major open questions in high energy physics and cosmology is the nature and origin of dark matter. Dark Matter in Astrophysics and Particle Physics 1998 provides a comprehensive overview of the current status of research in this topical field. The book brings together leading researchers from around the world to review recent progress and future directions for research in the different approaches to the dark matter problem. It collects results from cosmology, large-scale structure, and accelerator and nonaccelerator physics. The book also reviews the correlations between and the virtues of each of the fields for the determination of abundance, nature, and origin of dark matter.

The Fourth HEIDELBERG International Conference on Dark Matter in Astro and Particle Physics, DARK2002, was held in Cape Town, South Africa, in the period 4-9 February 2002. This majestic natural area was the site of the first conference of this series (hosted since 1996 in Heidelberg) to be held outside of Germany. Dark Matter has become one of the most exciting and central fields of as trophysics, particle physics and cosmology. The conference covered, as usual for this series, a large range of topics, theoretical and experimental. Topics included Astronomical Evidence for Dark Matter, the Cosmic Microwave Background, Supersymmetry, Inflation and Dark Energy, Structure Formation, Hot and Cold Dark Matter, and Ultrahigh Energy Cosmic Rays all of which were represented by experts in the field. It was very nice to see again many of our 'old' friends in Dark Matter here in South Africa. The organizers were very glad to see, in addition to world experts, the new generation here. Many young participants gave very nice professional talks during the conference. We are grateful to John Ellis for doing an incredible job preparing his excellent summary talk during the sessions. Some special interest and intensive discussions were naturally raised by the first announcement of terrestrial evidence for hot dark matter, obtained from neutrino less double beta decay. This now adds to the evidence for cold dark matter which we have from DAM A for several years already, and which remained unchallenged up to now by other experiments.

Unified Field Theory was an expression first used by Einstein in his attempt to unify general relativity with electromagnetism. Unified Field Theory and Occam's Razor attempts to provide real answers to foundational questions related to this unification and should be of high interest to innovative scientists. A diverse group of contributing authors approach an old problem with an open-mindedness that presents a new and fresh perspective. The following topics are discussed in detail in the hope of a fruitful dialogue with all who are interested in this subject:This highly original book brings together theoretical researchers and experimentalists specialized in the areas of mathematics and epistemology, theoretical and experimental physics, engineering, and technology. For years they have worked independently on topics related to the foundations and unity of physics and have had numerous overlapping ideas in terms of using Clifford algebra and spinors. Within the book, new technology applications are outlined and theoretical results are complemented by interpretations of experimental data.

Dark matter in the Universe has become one of the most exciting and central fields of astrophysics, particle physics and cosmology. The lectures and talks in this book emphasize the experimental and theoretical status and perspectives of the ongoing search for dark matter, and the future potential of the field into the next millennium, stressing in particular the interplay between astro- and particle physics.

Dark matter and dark energy are one of the central mysteries in modern physics, although modern astrophysical and cosmological observations and particle physics experiments can and will provide vital clues in uncovering its true nature. The DARK 2009 Conference brought together World's leading researchers in both astrophysics and particle physics, providing an opportunity and platform to present their latest results to the community. The topics covered are wide-ranging, from terrestrial underground experiments to space experimental efforts to search for dark matter, and on the theoretical aspects, from the generating of a fifth family as origin of dark matter, extra dimensions and dark matter to non-standard Wigner classes and dark matter. One of the new highlights was certainly a possible connection between a neutrino mass as observed by nuclear double beta decay and the dark energy. Highly important and relevant in its field, the book presents a vital snapshot of the sometimes seemingly disparate areas of dark matter research and offers an exciting overview of current ideas and future directions.