December 13, 2006

The Collapse of Dark Energy?

The Collapse of Dark Energy?

‘Dark energy’ is only an inference. There is not a single particle or track in a bubble chamber to prove that it exists.

Louise Riofrio, in an email to Open Source, December 8, 2006.
Nova art

Artist’s rendering of a nova explosion [adriangonsalves / Flickr]

Dark energy has nothing to do with football, but the discovery of a massive supernova led Gregg Easterbrook to devote a portion of his Tuesday Morning Quarterback column to the possibility that dark energy might not exist after all. I happened to catch Easterbrook’s departure from his football beat, and got curious. Current theory asserts that most of the universe is made up of dark energy. If dark energy doesn’t exist, the theoretical consequence is the collapse of the universe, which seems like a pretty big deal.

The new supernova that got Easterbrook speculating apparently violates a Nobel Prize-winning mathematical proof that supernovas of this type are always a uniform mass and brightness. To fly rapidly down the chain of logic here: math says supernovas are all the same brightness (standard candles); because they’re the same, we can use them to measure distance; because we can measure this distance, we can measure acceleration; because we see acceleration, we think there’s dark energy. Dark energy is an inference about something we observe, but can’t otherwise explain, like Newton (or perhaps Aristotle) trying to explain why things fall down.

A quick search for “dark energy” and “supernova” turned up an entry on researcher Louise Riofrio’s blog A Babe in the Universe. I emailed her for a fuller explanation of the stakes:

If supernovae are not standard candles, then the whole case for an ‘accelerating universe’ would fall apart. Red shifts are the only evidence for acceleration. The other supports are highly dependent on priors: Simulations of large-scale structure and interpretations of the cosmic microwave background. These latter two tell nothing at all about acceleration.

Louise Riofrio, in an email to Open Source, December 8, 2006.

I also emailed Harvard Professor Robert Kirshner, author of The Extravagant Universe, who conveniently happens to be the faculty member affiliated with my dormitory. He assured me that that the accelerating universe model is not on the verge of collapse. According to Kirshner, in the unlikely event that astrophysicists had accidentally included a few extra-bright supernovas in previous calculations, it would not affect the support for dark energy.

Even if there is one supernova (out of about 200 that have been studied well enough to see this) that doesn’t behave like the others, as long as you can recognize it as an oddball, and set it aside, it will not affect the reliability of your measurements of the history of cosmic expansion that lead to the inference of dark energy. The only way these [massive supernova] guys would mess it up would be if you didn’t recognize them as different and mixed them in with the others. Even then, these events cannot be the explanation for the observations that lead to the idea of an accelerating universe driven by dark energy because they are brighter than average… If these guys are mistakenly included, then there must be even MORE acceleration than we have inferred so far.

Professor Robert Kirshner, in an email to Open Source, December 8, 2006.

Related Content

  • Ben

    BBC’s In Our Time ran a great show on Dark Energy. Really cool stuff. Listening to the guests was a great mind-bender. Any chance of this moving to the warming up area?

  • Nick

    Ben’s got a great idea, and I wanna piggyback with two (and a half) proposals:

    One of ROS’s most intellectually stimulating shows – a ‘top ten’ show, no less – was The Holy Grail of Physics hour with Lisa Randall. Its thread was great, the show just as provocative. It demonstrated that physics, when explained in simple English, isn’t dry and arcane but fascinating and accessible.

    Physicist Lee Smolin’s theory in The Life of the Cosmos is as deserving of a ROS hour as any other scientific topic:

    Using Darwin’s and Einstein’s ideas the author suggests that the laws of nature are not fixed, but that they evolve in the same way that living things evolve. Smolin puts forward the possible unification of biology and physics to provide a view of the cosmos beyond both the notion of God and the existentialists.

    Significantly, Smolin says that he doesn’t like theories he can’t explain in plain English.

    In his newest book, Smolin, who has worked on String theory, gets even more downright skeptical than most scientists are by professional nature most of the time:

    In this groundbreaking book, the renowned theoretical physicist Lee Smolin argues that physics (the basis for all other science) has lost its way. The problem is string theory, an ambitious attempt to formulate a theory of everything that explains all the forces and particles of nature and how the universe came to be. With its exotic new particles and parallel universes, string theory has captured the public’s imagination and seduced many physicists. But as Smolin reveals, there’s a deep flaw in the theory: no part of it has been proven, and no one knows how to prove it. As a scientific theory, it has been a colossal failure. And because it has soaked up the lions share of funding, attracted some of the best minds, and penalized young physicists for pursuing other avenues, it is dragging the rest of physics down with it.

    1. It seems to me that an hour pairing Smolin with Randall would offer a potentially illuminating debate over String theory. (Brian Green and his melodious larynx is another obvious candidate for an hour like this.)

    2. I’m reading physicist Amit Goswami’s The Self-Aware Universe. Using the lessons of Quantum Physics, it posits that the energy of the universe – subatomic particles – aren’t ‘things’ but waves, or, more precisely, ‘wavilces’. This of course isn’t controversial. His larger argument however is: the wavilces inhabiting our universe’s space-time is consciousness itself. In other words, the matrix of space-time and energy comprising our universe doesn’t ‘give rise’ to consciousness as an epiphenomenon as the material realists aver, but: consciousness is already immanent within the energy.

    This notion appeals strongly to my Inner Pantheist. Its uncritical and syncretic acceptance of all manner of human mysticism however irritates the unholy bejezus out of my Inner Skeptic (who lately has been ascendant within the realm of my Inner Schizophrenic).

    So, proposal number 2 is an hour with Amit Goswami and perhaps Lee Smolin again – or another physicist appropriately skeptical enough to serve as a foil. Even if the conversation ends unresolved, the hour would surely be stimulating. Cutting-edge radio.

    And besides, the credulity of my Inner Schizophrenic hangs in the balance. 😉

  • Nick

    oOpS! I forgot to include the coded link for Lee Smolin’s newest book, which is the subject of the second block-quote in the post above.

    The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next

  • jazzman

    Throughout history science has produced theories and when the accepted theories don’t comport with observations, the believers (scientists) in the theories are so invested in the “correctness” of their beliefs, they invent hypothetical entities or “if it were” scenarios to resolve the differences between the theories predictions and empirical observations.

    Ptolemy invented and added epicycles to support the geocentric model of the universe and account for observed planetary motion. Stephen Jay Gould invented the concept of punctuated equilibria to shore up the Darwinian Evolution model and evolutionary biologists convinced that DE has to be correct, produce a priori theories to support that model absent any empirical evidence.

    Proponents of the Big Bang universe model had to invent and add hypothetical entities to resolve huge discrepancies between observation and the theory. They believe that the universe is inflating (due to the outward expansion following that hypothetical explosion), and due to Hubble red shift observations that seem to indicate that the universe is expanding at an increasing rate, that there has to be some energy to propel this expansion. This energy cannot be directly observed, only inferred. Dark Energy is then adduced to support the belief that there is an increasing expansion.

    The same epicyclical solution was applied to resolve the discrepancy in the theory vs. observed gravitational effects. As there doesn’t appear to be enough mass in the universe to account for the observations then Dark Matter is dreamt up to fill the void.

    The geocentric universe was supplanted by the heliocentric model after about 500 years. In due time the Big Bang model and the Darwinian Evolution model will also be supplanted as those as there is scant evidence to support them (except mainly argumentum ad populum scientia fallacy) and eventually the epicyclical bandages will rupture as more contravening evidence is adduced.

    The house of cards upon which the BIG Bang with its attendant assumptions (the contradictions of any of them would sink a theory in any science save cosmology) will come tumbling down. It’s interesting to note that Professor Kirshner is willing to prop up his pet theory by dismissing the apparent violation of the standard candle constant as a statistical outlier and of no consequence.

  • jazzman

    Oops I meant the geocentric model lasted about 1500 years.

  • herbert browne

    I’m no evolutionary (nor any other sort of) biologist, but, given the available evidence (which is sketchy, deformed, and piled in odd, out-of-the-way places), I’d entertain better (or more pleasing?) extrapolations than Gould’s, if such were available. Ditto the cosmologists- who have come up with some interesting (and far-fetched… but we’re addressing far fetches, here) theories, given the accumulation of information.

    I listened to an hourlong interview with Smolin, on his book tour (via Weekday, on KUOW-FM), and confess to being encouraged by his presentation. His challenges of (and alternatives to) String Theory had a kind of “gut resonance” with me- and it wasn’t only his use of the language, I don’t think. I’d second the request for a confab with Smolin & Randall. ^..^

  • Jazzman wrote:

    Throughout history science has produced theories and when the accepted theories don’t comport with observations, the believers (scientists) in the theories are so invested in the “correctness” of their beliefs, they invent hypothetical entities or “if it were” scenarios to resolve the differences between the theories predictions and empirical observations.

    Its great to see someone mentioning this theme.

    I would like a criticism at my attempt of a “Copernican switch” applied to the mass-based gravitational theories of Newton and Einstein which has taken me years to develop.

    Newton was well aware with the problems of his mass-based gravitational theory and he had hoped that future generations the problems associated with this basis which I do not think they have. Here are two quotes

    of his regarding this problem.

    My alternate gravity theory posits that the gravitational force is mediated by the “radial spreading of infrared luminosity.” See photograph

    above where two of my experiments demonstrate that the spreading of infrared luminosity is attractive contrary to what the introductory textbooks in physics would have you believe.

    It just so happens that the timing of the “dimming of the universe” coincides with its “acceleration”. If there is less light in the universe, according to my theory, the universe will be less gravitationally bound. Since galaxies rotate around other galaxies and clusters of galaxies rotate around other clusters, the galaxies and clusters will be free fly in a straight line if they become less gravitationally bound. This flying apart in all directions will give the appearance that the expansion rate of the universe is increasing or the universe is accelerating. Form more on this go here or here