I delivered the opening plenary talk in 2019 for the Centennial International Conference celebrating the 100th anniversary of the 1919 famous
solar-eclipse expedition and experiment that confirmed the theory of General Relativity of Einstein. The conference took place
in the town of Sobral in Brazil in May 2019 (exactly 100 years after the original expedition of 2019), where, at the time, the
geographical location of the town allowed the best measurement of the deflection of light by the Sun during the eclipse.
A key element is that Einstein's theory of gravity predicts a deflection of light twice the size of that predicted by Newton's
gravity, and the Sobral's measurement confirmed exactly that! The result in 1919 was a turning point in history confirming
for good the theory of General Relativity of Einstein. The event in 2019 was sponsored by the International Union of Astronomy,
involved many physics and astronomy societies, and was echoed all over the world, reaching the New York Times and the Washington Post.
The event was a real journey thru space and time.
1. "The Acceleration of the Cosmos and Tests of Gravity at Large-Scales in the Universe"
Colloquium presented at Kensas State University,
Manhattan, Kensas (December, 2019)
2. "The Acceleration of the Cosmos and Test of General Relativity at Large Scales in the Universe."
Invited Plenary Opening talk at the International Conference to celebrate the Centenary Anniversary of the famous 1919 Eclipse experiment that confirmed General Relativity of Einstein. Sobral, Brazil (May, 2019).
3. "Testing Modifications to Gravity (MG) and Cosmic Acceleration using LSST"
Invited talk presented at the LSST workshop at Texas A&M University,
College Station, Texas (November, 2019)
4. "Dark Energy & The Accelerating Universe"
Colloquium presented at LeTourneau University,
Longview, Texas (March, 2019).
5. "Why is the expansion of the universe accelerating?"
Colloquium presented at Baylor University,
Waco, Texas (October, 2018).
6. "Some Open Problems in Physical Cosmology"
Invited lecture at the Center for Values in Medicine, Science and Technology, UT-Dallas, Texas (October, 2018).
7. "A cosmic conundrum: inconsistency tests between cosmological data sets"
Invited presentation for press briefing at the 232nd Annual Conference of the American Astronomical Society, Denver, Colorado (June 2018).
8. "Cosmology for future generations"
Invited presentation at the Back to Space Day,
UT-Dallas, Texas (October, 2018).
9. Why is the expansion of the universe accelerating?
Public Lecture at the Perot Museum of Sciences in Dallas,
Dallas, Texas (October, 2017).
10. Why is the expansion of the universe accelerating?
Colloquium presented at University of Texas at Arlington,
Arlington, Texas (September, 2017).
11. Cosmological consistency tests of gravity theory and cosmic acceleration.
Testing Gravity Meeting 2017 at Simon Frazer University
Vancouver, British Columbia (January, 2017)
12. Why is the expansion of the universe accelerating?
Colloquium presented at Baylor University,
Waco, Texas (September, 2016).
13. Why is the expansion of the universe accelerating?
Colloquium presented at the monthly meeting of the Texas Astronomical Society,
UT-Dallas Campus (October, 2016).
14. Exact Solutions to Einstein's Equations in Astrophysics.
Invited plenary talk presented at 28th Texas Symposium on Relativistic Astrophysics in Geneva, Switzerland (December 2015).
15. Why is the expansion of the universe accelerating?
Colloquium presented at the University of Dallas, Irving, Texas (November, 2015).
16. Why is the expansion of the universe accelerating?
Colloquium presented at the Texas Christian University, Fort Worth, Texas (November 2015).
17. Cosmology and Astrophysics at UT-Dallas.
Invited presentation at Building Astronomy in Texas Meeting at Texas A&M, College Station, Texas (September 2015).
18. Two Big Puzzles in Modern Cosmology: Dark Energy and Dark Matter
Invited Public Lecture at the Physics Symposium: Through a Cosmos Darkly at the South Methodist University, Dallas (April, 2015).
19. Current Constraints on Dark Energy and Modified gravity
Invited plenary talk presented at the international meeting on Testing Gravity 2015, Vancouver, Canada (January, 2015).
20. Why is the expansion of the universe accelerating?
Colloquium presented at the University of North Texas. Denton, TX, (October, 2014).
21. Testing Gravity at Cosmological Scales .
Selected talk presented at the Dark Energy Science Collaboration LSST meeting. University of Pennsylvania, PA (June, 2014).
22. Invited talk presented to the Society of Physics Students, UT-Dallas, TX. (October, 2014)
Open Questions in Cosmology.
23. Presentation plus reception of the Robert S. Hyer Award for excellence in research at the Joint Fall 2013 Meeting of the Texas Section of the American Physical Society. "Recent Progress on Testing General Relativity at Cosmological Scales and Implications for Cosmic Acceleration". (Brownsville, TX, October 2013).
24. Selected talk at the Cosmo2013 Cosmology Conference.
"Testing General Relativity at Cosmological Scales".
(Cambridge, UK, 2013).
25. Invited presentation at the yearly client appreciation event by Cadent Capital. "Our expanding universe: why is the expansion of the universe accelerating?"
(Richardson, TX, 2013).
26. Colloquium at the Texas A&M at Commerce, "Why is the expansion of the universe accelerating?" (T&M Commerce, TX, 2013)
27. Colloquium at the University of Texas at San Antonio, "Why is the expansion of the universe accelerating?" (UTSA San Antonio, TX, 2012)
28. Colloquium at the University of Texas at Dallas, "Why is the universe expansion accelerating?" (UTD Richardson, TX, 2012)
29. Invited Presentation at the NSM Advisory Council meeting, 'The UTD Cosmology Research Efforts in Understanding the Problems of Dark matter and Dark Energy." (Richardson, 2012)
30. Colloquium at the University of Texas at San Antonio, "Why is the expansion of the universe accelerating?" (UTSA San Antonio, TX, 2012)
31. Colloquium at the University of Texas at Dallas, "Why is the universe expansion accelerating?" (UTD, TX, 2012)
32. Invited Presentation at the NSM Advisory Council meeting, 'The UTD Cosmology Research Efforts in Understanding the Problems of Dark matter and Dark Energy." (Dallas, Nov. 2012)
33. Colloquium at Baylor University, "Why is cosmic expansion accelerating?" (Baylor, TX,2011)
34. Invited plenary talk On Cosmic Acceleration at the Joint Fall 2011 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS, Volume 56, Number 7, (Commerce, TX, 2011)
35. Colloquium at University of Oklahoma, "Why is cosmic expansion accelerating?" (Norman, OK, 2011)
36. Invited plenary talk on Cosmic Acceleration at the 8th International Conference on Theoretical Physics at University of Constantine, (Constantine, 2011).
37. Invited parallel talk on Inhomogeneous models and Cosmic Acceleration at the 8th International Conference on Theoretical Physics at University of Constantine, (Constantine, 2011).
38. Colloquium at the Louisiana State University, Baton Rouge, LO, 2010.
Why is the expansion of the universe accelerating?
39. Colloquium at the University of New Mexico at Socorro, NM, 2010.
Why is the expansion of the universe accelerating?
40. Colloquium at the University of Texas at Brownsville, Brownsville, TX, 2010.
Why is the expansion of the universe accelerating? One of the biggest puzzles in cosmology!
41. Public Lecture to the Texas Astronomy Society, University of Texas at Dallas, Richardson, TX, 2010.
Why is the expansion of the universe accelerating?
42. Colloquium at the University of Texas at Arlington, Arlington, TX, 2010.
Why is the expansion of the universe accelerating? One of the biggest puzzles in cosmology!
43. The Invisible Universe - Dark Matter and Dark Energy
Talk given at the STEM Saturday event at UT Dallas, Fall 2010.
44. What is it to be an Astrophysics Professor at a University?
Series of talks given at Career Day at SMS Middle School in Plano Independent School District, Fall 2010.
45. Refereed talk at the 12th Marcel Grossmann Meeting on General Relativity and Gravitation, UNESCO, Paris, 2009.
Apparent Acceleration Due to Relativistic Cosmological Models More Complex than FLRW as a Possible Alternative to Dark Energy.
46. Invited talk at the Texas Cosmology Network Meeting, University of Texas at Austin, Austin, TX, 2009.
The growth rate index of large scale structure as a probe of cosmic acceleration.
47. Colloquium at Baylor University, Baylor, 2009.
Dark Energy or Apparent Acceleration Due to a Relativistic Cosmological Model More Complex than FLRW?
48. "The Invisible Universe - Dark Matter and Dark Energy", talk given at the STEM Saturday event at UT Dallas (Dallas, 2009).
49. Invited review talk at the Auresian Workshop on Astronomy and Astrophysics, Batna, Algeria, 2008. Cosmic Acceleration: A Review.
50. Colloquium at the University Mentouri, Constantine, Algeria, 2008.
Modern Cosmology: Current status and news challenges.
51. Selected presentation at the Origin of Dark Energy Conference, Waterloo, ON, 2007.
Dark Energy versus Modified Gravity Models: Probing Cosmic Acceleration Beyond the
Equation of State.
52. Colloquium given at NASA Goddard Space Flight Center, Baltimore, MA, 2006.
Cosmic acceleration: Dark Energy or Modified gravity?
53. Colloquium given at the Southern Methodist University, Dallas, TX, 2006.
Cosmic Acceleration: A Dark Energy Component or a Signature of Modified Gravity at
Cosmological Scales?
54. Invited talk at the 1st Texas Cosmology Network Meeting at the University of Texas at
Austin, Austin, TX, 2006.
Gravitational Weak Lensing and Cosmic Acceleration
55. Seminar given at the Johns Hopkins University, Baltimore, MD, 2005.
Current and future constraints on Dark Energy parameters,
56. Colloquium given at Austin College, Sherman, TX, 2005.
Recent progress in cosmology and the cosmic acceleration problem.
57. Selected talk at the 3rd Oxford-Princeton Workshop on Cosmology, Princeton, NJ, 2005.
Probing decisive answers to dark energy questions from cosmic complementarity and
lensing tomography.
58. Colloquium given at the University of Texas at Dallas, Richardson, TX, 2005.
Dark Energy Questions and Cosmological Probe.
59. Selected talk at the Workshop on Gravitational Lensing, Dark Energy, and Dark Matter at
the Ohio Center for Theoretical Science, the Ohio State University, Columbus, OH, 2005.
Dynamical Dark Energy: Current and future constraints from cosmic complementarity and
weak lensing tomography.
60. Seminar given at the Gravitational Lensing Workshop at the Institute for Advanced Studies,
Princeton-IAS, NJ, (2004). Model-dependent and independent constraints on dark energy from weak lensing (cosmic shear) tomography.
61. Seminar given at the Princeton University & Institute for Advanced Studies joint
Gravitational Lensing Seminar. Princeton, NJ, (2004).
Future constraints on Dark Energy from complementary observations and weak lensing
tomography (a critical discussion).
62. Seminar given at the Gravity Group at Princeton University, Princeton, NJ, (2003).
Inverse Problems In General Relativity and the Cosmic Acceleration.
63. Invited talk given at the 13th Kingston Theoretical Astrophysics Meeting, University of
British Columbia, Vancouver, BC, (2003).Weak Lensing and CMB: Cosmological parameter forecasts including a running spectral index.
64. Seminar given at the Canadian Institute for Theoretical Astrophysics, Toronto, ON, (2002).
GRDB and applications to astrophysics and cosmology.
65. Seminar given at the joint astrophysics seminars of University of Montreal and McGill University, Montreal, QC, (2002). An inverse approach to Einstein Field Equations: fitting cosmological model.