Unless you’re an astrophysicist, you probably don’t sit around thinking about dark energy all that often. That's understandable, as dark energy doesn’t really affect anyone’s life. But when you stop to ponder dark energy, it's really rather remarkable. This mysterious force, which makes up the bulk of the Universe but was only discovered 17 years ago, somehow is blasting the vast cosmos apart at ever-increasing rates.
Astrophysicists do sit around and think about dark energy a lot. And they’re desperate for more information about it as, right now, they have essentially two data points. One shows the Universe in its infancy, at 380,000 years old, thanks to observations of the cosmic microwave background radiation. And by pointing their telescopes into the sky and looking about, they can measure the present expansion rate of the Universe.
But astronomers would desperately like to know what happened in between the Big Bang and now. Is dark energy constant, or is it accelerating? Or, more crazily still, might it be about to undergo some kind of phase change and turn everything into ice, as ice-nine did in Kurt Vonnegut's novel Cat's Cradle? Probably not, but really, no one knows.
The Plan
Fortunately astronomers in West Texas have a $42 million plan to use the world’s fourth largest optical telescope to get some answers. Until now, the 9-meter Hobby-Eberly telescope at McDonald Observatory has excelled at observing very distant objects, but this has necessitated a narrow field of view. However, with a clever new optical system, astronomers have expanded the telescope’s field of view by a factor of 120, to nearly the size of a full Moon. The next step is to build a suite of spectrographs and, using 34,000 optical fibers, wire them into the focal plane of the telescope.
“We’re going to make this 3-D map of the Universe,” Karl Gebhardt, a professor of astronomy at the University of Texas at Austin, told Ars. “On this giant map, for every image that we take, we’ll get that many spectra. No other telescope can touch this kind of information.”
With this detailed information about the location and age of objects in the sky, astronomers hope to gain an understanding of how dark energy affected the expansion rate of the Universe 5 billion to 10 billion years ago. There are many theories about what dark energy might be and how the expansion rate has changed over time. Those theories make predictions that can now be tested with actual data.
Read More
"Hand me a clamp, stat," a skinny guy in a white lab coat says with some urgency. An older man, who had been standing back from the messy melee, looks over the shoulder of the first man. "Quick, the blood's going everywhere," he says. He's holding a syringe full of bright blue liquid.
"OK, OK," says another white-coated man, hurrying off. He returns a few seconds later. "Got the clamp. And some gauze as well."
I stand in the corner of the room for a few minutes and watch the men operate on the patient. Eventually, when everything seems to have stabilised, I cautiously take a step towards the workbench and assess the damage. "Is it usually this messy?" I ask, looking down at a mound of sodden tissues, pipes, pumps, and syringes. The whole thing throbs gently, rhythmically, unnervingly.
"Yep, I'm afraid so. We still have a few bugs to iron out with the 5D electronic blood..."
* * *
