Could dark energy just be discrete space-time?

If there’s anything in the cosmos more mysterious than dark matter, it’s probably dark energy. It makes up more than two-thirds the energy in the universe and encourages the universe’s accelerating expansion. Yet no one has the slightest clue what it is. Some undiscovered particle? A cosmological constant? Or perhaps dark energy emerges as a sign that space and time aren’t what they seem.

Every graduate student who studies particle theory suspects at one time or another that space-time might be discrete. There's a surprising reason behind that: the sums at the heart of quantum field theory are hopelessly, woefully infinite, primarily because the theory misbehaves at very short distances — ironically, this is exactly the reason it's so hard to figure out a quantum theory of gravity. If we just made it so there was a smallest possible distance, a tiniest possible step you could take, that problem would evaporate. But theorists figured out another way to deal with most of the infinities — one that does a remarkable job of explaining how particles behave — and anyway, how do you define a tiniest step? What should it look like?

Well, it should look like a pyramid. Space and time really might not be what they seem.

That view, recently proposed in the journal PLOS One, stems from a controversial idea called dynamical triangulation. First proposed as a theory of quantum gravity, DT holds that minute tetrahedrons—triangle-bottomed pyramids—are the fundamental units of space and time. Viewed from a distance, these units disappear into the smooth, continuous world of everyday life. Up close, churning stacks of tetrahedrons bend left, right, front, and back—and that’s where dark energy might lie. Calculations suggest that energy stored in the bends is distributed almost uniformly, just as observations suggest dark energy should be. And while the model’s predictions for dark energy’s density are rough at best, they manage to come within a factor of ten of the measured value, something quantum field theory ignominiously fails to do—it misses the mark by a factor of 10^107, or 1 followed by 107 zeros.

An economist walks into a bar...

First, HOLY COW IT'S BEEN A WHILE. Well, that's what having a baby will do to you, I suppose. That, and Twitter. I'm still recovering, but in the meantime, I'll be posting some short stuff I wrote that didn't, for whatever reason, end up in print. Some of it is...old. But still fun! Enjoy.

Cheers,
Nathan E. Science

Liquor is big business in the U.S., and with drunk drivers involved in about 40 percent of traffic fatalities, it’s also a serious public health threat. Acting on the assumption that drinking leads to increasingly risky decisions, many states prohibit happy hours or serving alcohol to clearly intoxicated people. But is the “more liquor, worse choices” axiom correct?

To find out, a team of economists armed with a breathalyzer and a laptop headed to a bar in New York’s Lower East Side. Once there, they asked 317 men and women of varying inebriation to make different bar-oriented decisions—between different combinations of sliders and dumplings, or between different cash lotteries—all the while looking for subtle inconsistencies in their subjects’ choices. Remarkably, even stumbling-drunk participants made sensible choices. The main exception: as they drank more, women became slightly more comfortable taking risks when choosing between lotteries.

If confirmed by further experiments, the results suggest that efforts to curb drunk driving or other negative consequences of drinking should focus on making better decisions while drinking rather than on discouraging drinking in the first place. The paper appeared last June in the Journal of Risk and Uncertainty.

People Are Ignorant. Big Deal, Right? Well, Yeah.

We've been on the theme of political ignorance for nearly a month now, and so far we've concluded that people are generally pretty ignorant, but we don't yet understand whether this is such a bad thing. Recall from last time there were three arguments about whether political ignorance matters.

Science, Reporters, Teaching, and More Coffee: Part II

Every year, or most every year at least, I head off to Eastern Washington University to teach and counsel at Satori, a summer camp for kids who like to learn stuff—and learn them we instructors do. But in between learnings, there’s a lot of time for conversation and a lot of time for a lot of coffee. Seeing as I’m a reporter now, I have an excuse to talk to anyone about anything, so I asked Thomas Hammer barista-manager Abby* whether she’d talk with me about science. She cheerfully obliged, though she also had to work. When she was off doing that, Satori director and Spokane school teacher Mike Cantlon filled in, making for an interesting back-and-forth that ranged from—well, this to that and a number of places in between.

Science, Reporters, Teaching, And More Coffee: Part I

Every year, or most every year at least, I head off to Eastern Washington University to teach and counsel at Satori, a summer camp for kids who like to learn stuff—and learn them we instructors do. But in between learnings, there’s a lot of time for conversation and a lot of time for a lot of coffee. Seeing as I’m a reporter now, I have an excuse to talk to anyone about anything, so I asked Thomas Hammer barista-manager Abby* whether she’d talk with me about science. She cheerfully obliged, though she also had to work. When she was off doing that, Satori director and Spokane school teacher Mike Cantlon filled in, making for an interesting back-and-forth of sorts that ranged from—well, this to that and a number of places in between.

In case you missed it...

A few, short, cool stories I did for ScienceNOW. Check them out. Comment and ask me questions in the comments!

When Predators Attack!
Watch out!

Toward Shatterproof Glass
Possibly helpful when dealing with predators.

How to cloak a Fisher space pen...or a satellite

There's an apocryphal story that, faced with the fact that ballpoint pens don't work in zero gravity, NASA paid a lot of money to develop the Fisher space pen. Meanwhile, the Russians used pencils.

"A Snapshot of the Inside of an Atom" at ScienceNOW

My first story for ScienceNOW in quite a long time, and it's a fun one. Scientists at FOM Institute AMOLF took a picture of the quantum wave function of electrons as they emerged from hydrogen atoms.

Wave function? AMOLF? Google the latter. As for the former, the wave function is the fundamental piece of quantum weirdness, something that physicists have tried to wrap their heads around for eighty or ninety years — and failed. For more, read the story.

Seeing the Forest for the Splotchy Green Blob

Lesson for today: statistics is hard. Specifically, it's hard to sort out real patterns from random noise, especially when you don't have a lot of data. Nonetheless, people sure do their darndest.

Coffee Science with Four Barrel's Alex Powar

We're talking chemistry. Sort of. "Chlorogenic acid, for instance, esterizes into quinic and caffeic acid. Quinic acid...so that produces a lot of bitterness. That's why you never want to reheat coffee. It catalyzes that reaction."