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That would explain the difference between the photograph and the radio picture. Trouble is that if the quasars are really twin images formed by a gravitational lens from the light of a single quasar, they should be mirror images of each other. But, as Burke points out, "we don't see mirror images of the spraying material with the other quasar." The M.I.T. team and others plan more radiotelescope observations in the hopes of confirming that the jets are being ejected from one quasar and detecting similar ones streaming from the other. Concludes Burke: "If the mirror images are not found, it will make life very difficult for those who propose a gravitational lens."
Then how do the M.I.T. scientists explain the remarkable similarity in the velocities and chemical characteristics of the quasars? If both formed and evolved at about the same time and in the same environment, they say, there is every reason for them to be virtual twins. If they are indeed twins, scientists will try to make use of their proximity. Explains Burke: "If this is a pair of quasars and we find evidence of interaction, we could then measure their masses and get a better handle on what the nature of these objects might be." And because scientists see the quasars now as they were 10 billion years ago, studying the twins should teach them more about what the universe was like when it was very young.
* A light-year is 5.8 trillion miles, the distance that light travels in a year.