There are three reasons why we probably shouldn’t post this: (1) it’s off topic; (2) it’s loaded with math; and (3) it may be all wrong. Nevertheless, if it’s not wrong it’s important, so we’ll tell you what we know.
This is about some work by Dr. Arto Annila, a physics professor at the University of Helsinki. He’s written a paper, published in Monthly Notices of the Royal Astronomical Society, and available (at least the abstract) at the website of the Wiley Online Library. It’s titled Least-time paths of light. He says that the Universe is expanding uniformly — not at an increasing rate — and that all observations to the contrary can be explained without invoking dark energy and dark matter.
This is potentially of enormous importance, especially since the Nobel Prize in Physics for 2011 was recently awarded to Saul Perlmutter, Brian P. Schmidt, Adam G. Riess “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.” According to the press release announcing the Prize:
The teams used a particular kind of supernova, called type Ia supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected – this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.
Now, just as we’ve all been getting used to the idea that the universe is expanding at an ever-increasing rate, and will probably never collapse in a Big Crunch, somehow resulting in another Big Bang — thus ending the idea of an eternally-oscillating universe — along comes Dr. Arto Annila with a different interpretation of the data. So we’re intrigued, even though we don’t pretend to follow all of the arguments.
The most coherent explanation we’ve found is at the website PhysOrg: A second look at supernovae light: Universe’s expansion may be understood without dark energy. We’ll give you a very few excerpts, and then we’ll leave it up to you to decide what you make of it all. PhysOrg says, with bold font added by us:
The well-known problem resulting from these [Type 1a supernovae] observations is that this expansion seems to be occurring even faster than all known forms of energy could allow. While there is no shortage of proposed explanations – from dark energy to modified theories of gravity – it’s less common that someone questions the interpretation of the supernovae data itself.
In a new study, that’s what Arto Annila, Physics Professor at the University of Helsinki, is doing. The basis of his argument … lies in the ever-changing way that light travels through an ever-evolving universe.
“When the supernova exploded, its energy as photons began to disperse in the universe, which has, by the time we observe the flash, become larger and hence also more dilute,” he [Dr.Annila] said. “Accordingly, the observed intensity of light has fallen inversely proportional to the squared luminosity distance and directly proportional to the redshifted frequency. Due to these two factors, brightness vs. redshift is not one straight line on a log-log plot, but a curve.”
As a result, Annila argues that the supernovae data does not imply that the universe is undergoing an accelerating expansion.
We understood everything up to that last sentence. Let’s read on:
As Annila explains, when a ray of light travels from a distant star to an observer’s telescope, it travels along the path that takes the least amount of time. This well-known physics principle is called Fermat’s principle or the principle of least time. Importantly, the quickest path is not always the straight path.
The principle of least time is a specific form of the more generally stated principle of least action. According to this principle, light, like all forms of energy in motion, always travels on the path that maximizes its dispersal of energy. We see this concept when the light from a light bulb (or star) emanates outward in all available directions.
Okay. So far, so good. We continue:
Mathematically, the principle of least action has two different forms. Physicists almost always use the form that involves the so-called Lagrangian integrand, but Annila explains that this form can only determine paths within stationary surroundings. Since the expanding universe is an evolving system, he suggests that the original but less popular form, which was produced by the French mathematician Maupertuis, can more accurately determine the path of light from the distant supernovae.
Now we’re lost, and that seems to be right at the most important point. Here’s one more excerpt:
Using Maupertuis’ form of the principle of least action, Annila has calculated that the brightness of light from Type 1a supernovae after traveling many millions of light-years to Earth agrees well with observations of the known amount of energy in the universe, and doesn’t require dark energy or any other additional driving force.
He’s the first to think of this? Maybe so. We certainly didn’t think of it. Wait — we have to add this from the article:
Annila added that these concepts can be tested to see whether they are the correct way to analyze supernovae and interpret the universe’s expansion.
So there you are. There’s much more in the PhysOrg article, so of this interests you, click over there and check it out. Then let us know what you think. Hey, we’re talking about the fate of the universe!
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