Letters in High Energy Physics 2020-04-01T17:47:22+00:00 Professor Shaaban Khalil Open Journal Systems The Thermodynamics of Relativistic Multi-Fluid Systems 2020-04-01T17:47:22+00:00 Bob Osano <p>This article extends the single-fluid relativistic irreversible thermodynamics theory of Müller, Israel and<br>Stewart (hereafter the MIS theory) to a multi-fluid system with inherent species interactions. This is illustrated<br>in a two-fluid toy-model where an effective complex 4-velocity plays the role of a primary dynamical<br>parameter. We find that an observer who resides in the real-part of this universe will notice that their<br>knowledge of the universe parametrized using real, rather than imaginary, quantities are insufficient to fully<br>determine properties such as the total energy density, pressure or entropy, In fact, such an observer will<br>deduce the existence of some negative energy that affects the expansion of their perceived real universe.</p> 2020-04-01T17:16:01+00:00 ##submission.copyrightStatement##