Recurring Guest Characters Michio Kaku, PH.D., Author / Theoretical Physicist 5 guest appearances Michael Dennin, Ph.D. - Professor of Physics, UC Irvine 3 guest appearances Nick Pope, U.K. Ministry of Defense (1985-2006) 2 guest appearances Paul Sutter, Ph.D. - Author, Your Place in The Universe 2 guest appearances Paul Sutter, Ph.D. - Theoretical Cosmologist 2 guest appearances Ben McGee - Plantary Geophysicist 2 guest appearances Seth Shostak, PH.D., Senior Astronomer, SETI Institute 1 guest appearances Avi Loeb, PH.D., Chair of Astronomy, Harvard University 1 guest appearances Amy Shira Teitel - Author, Fighting for Space 1 guest appearances Amy Shira Teitel - Author, Breaking The Chains of Gravity 1 guest appearances Konstantin Batygin, Ph.D. - Prof. Planetary Science, CalTech 1 guest appearances Mike Brown, Ph.D. - Planetary Astronomer, CalTech 1 guest appearances Travis Taylor, Ph.D. - Astrophysicist / Aerospace Engineer 1 guest appearances