Why do we Need Dark Energy to Explain the Observable Universe?

Posted on September 27, 2009  Comments (2)

Why do we need dark energy to explain the observable universe?

Against all reason, the universe is accelerating its expansion. When two prominent research teams dropped this bombshell in 1998, cosmologists had to revise their models of the universe to include an enormous and deeply mysterious placeholder they called “dark energy.” For dark energy to explain the accelerating expansion, it had to constitute more than 70 percent of the universe. It joined another placeholder, “dark matter,” constituting 20 percent, in overshadowing the meager 4 percent that make up everything else—things like stars, planets, and people.

An accelerating wave of expansion following the Big Bang could push what later became matter out across the universe, spreading galaxies farther apart the more distant they got from the wave’s center. If this did happen, it would account for the fact that supernovae were dim- they were in fact shoved far away at the very beginning of the universe. But this would’ve been an isolated event, not a constant accelerating force. Their explanation of the 1998 observations does away with the need for dark energy.

And Smoller and Temple say that once they have worked out a further version of their solutions, they should have a testable prediction that they can use to see if the theory fits observations.

Another interesting example of the scientific inquiry process at work in cosmology.

Shouldn’t the National Academy of Science (NAS), a congressionally chartered institution, promote open science instead of erecting pay walls to block papers from open access? The paper (by 2 public school professors) is not freely available online. It seems like it will be available 6 months after publication (which is good) but shouldn’t the NAS do better? Delayed open access, for organizations with a focus other than promoting science (journal companies etc.), is acceptable at the current time, but the NAS should do better to promote science, I think.

Related: Physics from Universe to MultiverseLaws of Physics May Need a RevisionExtra-Universal MatterCosmology Questions Answered

2 Responses to “Why do we Need Dark Energy to Explain the Observable Universe?”

  1. Joe Taylor
    October 8th, 2009 @ 11:28 am

    This stuff just interests the heck out of me. I love to think about how or why the Universe would be accelerating it’s expansion. Is it possible, in our current physical state, that we’ll never be able to know? Are there forces outside of the Universe that are causing this affect? Like our entire universe spinning around something else outside of this space and time? O_O

    ..I love your blog. Even though I’m not a scientist, engineer, theoretical physicist and probably don’t understand 99.98% of it, lol, the general concepts I enjoy.



  2. Anonymous
    October 9th, 2009 @ 12:42 pm

    Hi,If the universe is 13.7 billion years old, it seems like the most distant object we could see would be 13.7 billion light years away. Light that left such an object would just be arriving at Earth now. Yet the most distant objects observable are much farther away than 13.7 billion light years. Explain how this can be the case. Be brief. what do you think?

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