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Recorded: 12/9/2017 Released: 6/6/2019

Randy introduces a theory that purports to allow negative mass to Jim. It has been thought for quite a long time that negative mass was incompatible with general relativity, because it is possible to show that negative mass solutions are impossible. However Paranjape and his students noticed the proofs of this all relied on a flat background (zero cosmological constant). When trying to extend the theorems to a space with a negative cosmological constant, they found instead that negative mass is not prohibited.

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Notes:

1. The papers we read for this program:

- BelletĂȘte, J. and M.B. Paranjape, "On Negative Mass." (2014). [arXiv]
- Mbarek, S. and M.B. Paranjape, "Negative Mass Bubbles in de Sitter Space-Time."
*Phys. Rev. D***90**, 101502(R) (2014). [arXiv]

2. Additional related paper for the positive energy theorem.:

- Komar, A., "Positive-Definite Energy Density and Global Consequences for General Relativity"
*Phys. Rev.***119**, 1873 (1963).

3. Related Episodes of Physics Frontiers:

- Physics Frontiers 25: Gravitational Field Propulsion
- Physics Frontiers 31: The Parameterized Post-Newtonian Framework

4. Details about just how well general relativity works can be found in Wills' Theory and Experiment in Gravitational Physics, whose work we reference in the podcast.

5. Please visit and comment on our subreddit, and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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