Ever since the Big Bang, 14 billion years ago, the universe has been expanding at an ever-accelerating rate. The culprit is a mysterious force called dark energy.
“If you threw up a ball, gravity would pull the ball back down,” said NASA cosmologist Jason Rhodes in an October 9 lecture at the American Association for the Advancement of Science. “But the effects of the universe, through this dark energy, are as if you threw up a ball, and instead of the ball coming back down, it kept going away from you faster and faster.”
Everything that we can see, including planets, stars, and gases, makes up less than 5% of the universe. Dark matter and dark energy, which neither give off nor absorb light, occupy the remaining space. But these forces can only be measured indirectly, with reference to their gravitational influence on other objects. Our understanding of the phenomena that dominate our universe, therefore, remains extremely limited.
Rhodes’ lecture, the latest installment in AAAS’ monthly series of public seminars, detailed the scientific priorities of NASA’s Wide Field Infrared Survey Telescope. A flagship mission set for launch in 2025, WFIRST will obtain precise measurements of the properties of dark matter and dark energy, while laying the groundwork for future missions that will look for signs of life in distant solar systems.