• Earth Has No Special Place in Expanding Universe

    Science Daily:

    New Light On Dark Energy, Cosmic Speed-Up: Big Bang Afterglow Shows Earth Has No Special Place in Expanding Universe

    Nov. 7, 2013 — In a new study, Dartmouth researchers rule out a controversial theory that the accelerating expansion of the universe is an illusion.

    While the findings don’t explain the cosmic speed-up, they eliminate one provocative possibility that our planet, solar system and galaxy are at the center of the universe and that there is no dark energy. The findings appear in the journal Physical Review D.

    The 2011 Nobel Prize was awarded for the discovery that the expansion of the universe is accelerating. One leading idea to explain the acceleration is a new, mysterious substance called dark energy, which is thought to make up nearly three-fourths of the energy of the universe. But another alternative is that Earth, our solar system and Milky Way galaxy are at the center of the universe. That theory violates the standard assumption that the universe has no center, but if true, then cosmic acceleration could be explained without dark energy or any new laws of physics.

    But Dartmouth researchers found that this model can’t hold up to other observational tests. The sky glows with light left over from the Big Bang, also known as the Cosmic Microwave Background, so they calculated how that glow would be affected. Their findings show that the model’s prediction is completely contrary to the glow that has been measured.

    “Essentially, we held a mirror up to the universe and asked if the reflection was special,” says Robert Caldwell, a professor of physics and astronomy who co-wrote the article with undergraduate physics major Nina Maksimova. “The reflection shows that we do not appear to live in a special location, and decisively excludes this explanation for the universe’s accelerating expansion. It would be a great relief to be able to understand a basic problem of cosmology within the known laws of physics, but our research is an important step in explaining the physics responsible for the cosmic acceleration.”

    The detailed, all-sky picture of the Cosmic Microwave Background in the infant universe reveals 13.77 billion year old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies. (Credit: NASA/WMAP Science Team)

    Category: cosmologyScience

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    Article by: Jonathan MS Pearce

    • Daydreamer1

      This is good. I’ve never really liked a physics argument that appears to rest on an assumption of humility.

      If a grand argument rests on ‘it is arrogant to assume we are at the centre and so we assume we are not’ then it is a weakness and easily dismissed by people who hold the alleged arrogant position.

      Good to see some science confirming our humility.

    • labreuer

      I’ve never understood why people try to measure Earth’s “importance” in these ways. They seem entirely artificial. There is a wonderful Physics Today article on the Copernican myths, which explained how the center of the universe was at times considered to be the butt-hole of the universe, and definitely not a noble place to be. Sadly, the article now costs money.

    • josh

      Just a quick comment that dark energy isn’t necessarily a ‘substance’ in any traditional sense.