#LabChat: What is Dark Energy?
The Dark Energy #LabChat on Oct. 25 yielded lively discussion with three physicists about inflation, super symmetry, black holes and, of course, dark energy. Here are a few of our researchers' best responses to questions about Dark Energy and physics.
Storified by Energy Department ·
Tue, Nov 06 2012 13:17:17
The #LabChat started with introductions as the researchers identified themselves and their institutions. Each works with one of most advanced cameras in the world to search for dark energy at the furthest reaches of the known universe.
Steve and Marcelle work on the Dark Energy Survey, a project aiming to understand why the universe is expanding.
Debbie Bard, SLAC National Accelerator Lab research associate, tweeted from the Twitter account, @SLAClab. Bard works in the laboratory's Kavli Institute for Particle Astrophysics and Cosmology developing the Large Synoptic Survey Telescope (LSST), a wide-field telescope to image faint astronomical objects to study the nature of dark energy through weak gravitational lensing techniques.
Apparently when you have three physicists on Twitter, you can skip right past the "easy" questions and plow into the details of super symmetry. But, for everyone who doesn't intimately know about dark energy, here's the researcher's 140-character-or-less explanations:
One of the first things you should know about dark energy is that you can't actually see it. These scientists can't point to a spot in the 570-megapixel photos the Dark Energy Survey collects each night and say, "That's dark energy."
@ENERGY You can't see dark energy directly, but you can see the effect it has on things we can see, like entire galaxies. #LabChat
You can sorta do this with Dark Matter.
Dark matter has a gravitational effect and forms clumps. Dark energy permeates the space between those clumps. @3klektic #LabChat
But as far as dark energy goes you only get to see the effects of the force on other bodies.
Supernovae are very good distance estimators, so studying them is a good way to measure the expansion of the universe. @ENERGY #LabChat
We observe galaxies and supernovae. From that, we determine the expansion rate of the universe. @ENERGY @rob_krol #LabChat
Scientists know that dark energy is the largest component of the universe, accounting for about 74 percent of the mass and energy that exists combined. So then what is Dark Energy?
@d_miceli This is the problem, there is no theory that gives a good picture. That's part of what's so fascinating. #LabChat
Current theories don't give a complete picture of dark energy yet. We need more data! @d_miceli #LabChat
According to Steve Kuhlmann in his Argonne Q&A: "The best explanation we have for how dark energy works generates predictions that are off by one hundred and twenty orders of magnitude. That’s a mind-bogglingly huge number – 10^120..."
In other words, a 10 followed by 120 zeros:
10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
"For the people who are making those predictions – high-energy physics theorists and particle physics theorists – it’s incredibly daunting."
Getting a glimpse of this dark force is these scientists' exact mission using the Dark Energy Camera, which just went online in September. It is undergoing further testing, and is expected to begin its five-year Dark Energy Survey in December. Over that time, it is expected to discover and measure 4,000 supernovae, 100,000 galaxy clusters and 300 million galaxies.
For the LSST, it'll take a little long until it sees it's first interstellar light. Construction is expected to begin in 2014 and take about five years, but once it's online it'll start pulling down 15 terabytes of photos from its 3.2-billion-pixel camera each night to produce the most detailed map of the Milky Way.
We are still a ways off from figuring out dark energy. In the meantime, here are a couple other great resources to learn more about dark energy - and dark matter.
FermiLab's Kurt Riesselmann illustrates dark matter and dark energy with jelly beans.
And, of course, here's Dr. Saul Perlmutter, 2011 Nobel Prize winner in Physics, presents his findings on observing supernovae - and what that means for dark energy.
Stay tuned to energy.gov/science and future #LabChat conversations as the researchers from the National Labs unlock the secrets of the Universe.
