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We Don't Need to Chuck Our Best Physics Theories to Explain Dark Energy

Despite what you may have heard.

by Michael Byrne
Jan 4 2015, 12:00pm

​Image: ..stiina../Flickr

​Dark energy is an effect in search of a cause. We know now that the universe is being thrown apart, ripped galaxy from galaxy; every moment it expands at a faster and faster rate. Astronomers are quite certain of this: An accelerating expansion is demanded both by our deepest theories of astrophysics and contemporary observations of galactic motion. The far future is indeed perfectly cold and perfectly dark. Forever. Thank dark energy.

Dark energy is like a negative pressure or reverse gravity pervading empty space. It's a force that is both the product of empty space and also the cause of it. It's also not defined in a really satisfactory way; we have a particle for light, but for dark, just this ghostly vapor of transient, "virtual" particles that exists without really existing.

This ambiguity makes it open season for often-sketchy contrarianism, the latest example of which comes courtesy of University of Georgia professor Edward Kipreos. ​In a recent paper, Kipreos argues that what we call dark energy may be less of a "thing" than an unlikely mutation of Einstein's theories of relativity, or how time is affected by gravity and motion. It's sketchy as hell, but making the rounds.

The theory has to do with what we call time dilation. In the presence of a very strong gravitational field, Einstein's general theory of relativity—in which energy and mass warp space-time—demands that time move slower (relatively). As the speed of light is always constant, everything else warps instead. Reality itself congeals.

This is something tested and observed ad infinitum and is not really in question. Relativity, however, has a variation, which is known as special relativity. This has to do with time as it relates to the motion of objects relative to other objects. Time slows down in the presence of strong gravitational fields, but it also slows due to the relative velocities/positions of different objects. A satellite whipping around Earth experiences less time than an observer on the planet's surface. Their clocks will fall out of sync.

The clocks with fall out of sync in a way that's symmetrical. That is, they'll be out of sync relative to each other. If I'm moving and you're moving, our clocks will be off in some unique way that accounts for both, which is IRL indisputable. Relativity isn't something that's just switched on and off according to arbitrary preferences.

What Kipreos suggests, however, is that this time dilation isn't symmetrical and, really, only one of the two objects has a screwy clock. This, he says in a peer-reviewed journal, could explain the acceleration of the universe's expansion.

His idea is a twist on what's called the Lorentz transformation, which goes something like this: First, consider that we all live in our own private frames of reference—a place (x,y,z) and time (t)—from which we observe the universe. This frame is different from someone else's frame, who observes the same universe from a different place. A different place, given that the speed of light never changes, means that instead of light going faster or slower to account for the different perspectives, everything else changes, the fabric of the universe itself twists around. It has to.

The Lorentz transformation takes my frame of reference (x,y,z) and maps it onto your frame of reference (other x, other y, other z), as we move with respect to each other.

"Special relativity is supposed to be reciprocal, where both parties will experience the same time dilation, but all the examples that we have right now can be interpreted as directional time dilation," Kipreos, who is by day a molecular geneticist, explained in a statement. "If you look at the GPS satellites, the satellite time is slowing down, but according to the GPS satellites, our time is not slowing down—which would occur if it were reciprocal. Instead, our time is going faster relative to the satellites, and we know that because of constant communication with the satellites."

It's not clear if any qualified physicist actually reviewed this work.

What Kipreos offers is an absolute version of the Lorentz transformation. Here, reality is forced to choose a "preferred reference frame," which is linked to the dominant center of gravity in a relativity relationship. So, when we look at the clocks of orbiting GPS satellites, we're allowed to imagine that time dilation/warping only occurs up there, and not really down here. It occurs in only one direction.

The dark energy implication goes like this. Because the universe is moving faster and faster outward, it's increasing in velocity with respect to the past. Five minutes from now the universe will be expanding faster than it is right now, and in terms of time dilation/special-relativity, time should be moving slower and slower in the future. Alternatively, we can say that time is moving slower now than it was five minutes ago.

If time were changing like this, it might explain why it appears that galaxies further away are moving faster, which is usually taken as evidence for cosmic acceleration. "The predicted effects of time being faster in the past would have the effect of making the plot of supernovas become linear at all distances," Kipreos said, "which would imply that there is no acceleration in the expansion of the universe. In this scenario there would be no necessity to invoke the existence of dark energy."

Neat.

Let's rewind a moment. What's being suggested here is that some motion and some gravity can be ignored if it's deemed to be not-dominant. This is basically a return to pre-Einstein thought, where it was assumed that the universe is governed by some absolute time-frame; everything has an absolute velocity compared to this base level frame of reference. That is some spectacular contrarianism: Not only was Einstein wrong, but the entire mainstream of physics is wrong as well, as are ​its experiments.

What's more, Kipreos is arguing that this absolute reference frame is Earth. How old-school.

"Any physicist worth her salt would flag this work as seriously lacking," ​writes Brian Koberlein, a science writer and physicist at the Rochester Institute of Technology, at One Universe at a Time. "The author himself should have caught the glaring flaws in this work. But then the author is actually a cellular biologist with no publishing record in physics. Throwing all relativity out the window in order to create a 'just-so' model of cosmology is what he does in his spare time. The editor of the journal should have flagged the work as well, but then his background is also biology."

"It's not clear if any qualified physicist actually reviewed this work," he continues,

Koberlein blames the journal, PLOS One, which is open-access (free) but peer-reviewed (quality controlled, but only for "technical accuracy"). The journal is funded not by readers, but by authors, who pay a publication fee of around $1,400 per submission. "On the one hand," Koberlein writes, "[open-access journals] get rid of the obscenely expensive paywall that limits access to research (much of which is publicly funded), but on the other hand they can be seen as 'pay to play' paper mills where anyone with enough cash can have the prestige of peer-reviewed work."

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