Our universe is such a great unknown. Are we one universe of many out there? What’s at the edge of the universe? Why is that Burger King dude so creepy?
But perhaps the hottest question in physics right now is: Why the heck is the universe accelerating?
You’ve probably heard of dark energy, a term scientists use as a fudge factor to explain observations published in 1998 that showed the expansion of our universe was actually accelerating. This was rather a surprise considering we had previously thought the expansion following the Big Bang was slowing due to gravitational effects.
Because we don’t understand dark nature we essentially don’t know what nearly three-quarters of our universe is made of. Yep. And we don’t know the fate of the universe, illustrated below, will be. If dark energy is constant, as many scientists now believe, the expansion should continue accelerating forever.
If dark energy increases, the acceleration may happen so quickly that galaxies, stars, and eventually atoms will be torn apart, in the so-called Big Rip. (That would be a lot worse than, say, the Bubonic plague.) And it’s possible that dark energy may also lead to a recollapse of the Universe, in the Big Crunch.
Today’s news is that The University of Texas at Austin ($3.6 million), Texas A&M University ($3.9 million) and Penn State University ($.5 million) have received grants to study the nature of dark energy with UT’s Hobby-Eberly telescope in West Texas.
The money will be used to construct a sophisticated spectrograph, called the VIRUS instrument, to study light coming in from distant galaxies to determine their motion.
The power of the spectrograph, to be built by Texas A&M, is in its ability to simultaneously capture spectra — detailed information about the incoming light — from 33,000 points on the sky. Here’s a few questions I had for Darren DePoy, an A&M instrument guru involved in the project.
How long will it take to make the VIRUS instrument?
We currently estimate it will take 1.5 to 2 years to complete the instrument. This includes producing the spectrographs, moving them to the Observatory, mounting on the telescope, etc.
Is there any existing spectrograph that can capture light from so many sources simultaneously?
No, VIRUS has 10-100 times more fibers (and hence can look at 10-100 times more objects simultaneously) than any other spectrograph ever built.
How can light from these different sources tell us about the expansion of the universe?
The redshift (the speed of the galaxies relative to us) of any galaxies observed by VIRUS maps out their distances and positions in the Universe, since the speed of recession of a galaxy is proportional to its distance (as discovered by Hubble). The degree to which these objects are clumped together allows us to measure the strength of dark energy.
If this experiment is successful how will it bring us closer to understanding the fundamental nature of dark energy?
Given our very crude understanding of what dark energy is (or even could be), improved determination of any characteristic of it helps to further our understanding. The HETDEX project is aiming at measuring the strength of dark energy at relatively high redshift, which, coupled with the results of other projects, will allow a measure of how much dark energy has changed over time (since looking at things far away is like looking at things a very long time ago).
I think this is great for a couple of reasons. First of all, as an astronomy major, I’m thrilled that such frontline astrophysical research is being done in the state of Texas. Second, it’s really only possible because Texas and A&M have pooled their resources to work together to obtain these kinds of large grants.
Now go find us some interesting results.
RELATED: As part of a satellite event to the big U.S. Science and Engineering Festival in Washington this weekend, Texas A&M will be having its own physics festival today. A&M Nobel Laureate Dudley Herschbach will lecture at 3:30 p.m. and the talk will be streamed live here.