LANL Abstract: on the Use of Antimatter as a Power Source by Extraterrestrial Civilizations

From: Amara Graps (
Date: Sat Dec 29 2001 - 23:53:31 MST

Astrophysics, abstract

From: Mike Harris <>
Date: Thu, 20 Dec 2001 17:41:17 GMT (122kb)

Limits from CGRO/EGRET Data on the Use of Antimatter as a Power Source by
Extraterrestrial Civilizations

Authors: Michael J. Harris (USRA/NASA-GSFC)
Comments: Submitted to "Astrobiology", 16 pp., 7 figs

     I argue that the existence of cold antimatter in bulk is not
     permitted by the Standard Model, so that if a gamma-ray signature
     from antiproton annihilation were to be detected, it must
     represent either new physics or the action of intelligence. Time
     variability of the signal would strongly support the second
     alternative. The entire sky was scanned at the relevant energies
     (30 - 928 MeV) by the EGRET experiment on board the Compton Gamma
     Ray Observatory during 1991 - 1995. A search of this database for
     the antiproton annihilation signature yielded only upper limits on
     the flux (an intriguing spectrum detected from QSO 2206+650 = 3EG
     J2206+6602 is probably not related to SETI). The all-sky longterm
     99% upper limit is 2.3 x 10^-8 photon/(cm2 s); it is a factor 10
     worse in the Galactic plane due to the higher diffuse gamma-ray
     background emission. I give brief, but quantitative, illustrations
     of what this limit means for nearby intelligent activities.

Paper: Source (122kb), PostScript, or Other formats

Amara Graps, PhD | Max-Planck-Institut fuer Kernphysik
Heidelberg Cosmic Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY *
"We came whirling out of Nothingness scattering stars like dust." --Rumi

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