By Ron Cowen
The mysterious cosmic push that’s tearing apart the universe began revving up about 5 billion years ago. But a new study reveals that several billion years earlier, the bizarre, elastic substance that fuels this push was lurking in the shadows and already beginning to fight gravity’s tendency to pull things together.
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The new report, based on 24 distant stellar explosions recorded by the Hubble Space Telescope, indicates that the substance, dark energy, was present in the universe 9 billion years ago. The observations also hint that dark energy, which pervades all space, might emanate from the cosmic vacuum and have a constant density. If so, dark energy would resemble the cosmological constant, which Albert Einstein conceived shortly after he developed his theory of gravitation more than 90 years ago.