What You Don't Know About the Big Bang

Heidi B. Hammel joined The Planetary Society's Board of Directors in 2005.  A Senior Research Scientist with the Space Science Institute in Boulder, Colorado, Hammel herself lives in Ridgefield, Connecticut.

She received her undergraduate degree from the Massachusetts Institute of Technology in 1982 and her Ph.D. in physics and astronomy from the University of Hawaii in 1988.  After a post-doctoral position at the Jet Propulsion Laboratory (Pasadena, California), Hammel returned to MIT, where she spent nearly nine years as a Principal Research Scientist in the Department of Earth, Atmospheric, and Planetary Sciences.

Hammel primarily studies outer planets and their satellites, with a focus on observational techniques.  Hammel received the  2002 American Astronomical Society's Division for Planetary Sciences (AAS/DPS) Sagan Medal for outstanding communication by an active planetary scientist to the general public .

  • Transcript


Topic: What You Don't Know About the Big Bang

Heidi Hammel: We think we know quite a bit about how the universe may have formed from the Big Bang, from nothing to something and then a period of inflation that then started everything moving outward from wherever it was. One of the most revolutionary things that’s happened in astronomy in just the last few years, though, has been a study of things that are going on in the distant, distant past. We look kind of back in time with our telescopes, and when we look at the most distant galaxies, which are pretty big. That’s why we can see them. We look at the supernovae in these galaxies because supernovae are exploding stars that are really bright so we can see them far away. We found something unanticipated. What we found was that those distant, distant objects were actually accelerating away from us, not just moving away from us, but moving faster and faster the further we looked, which is nuts. I mean, it’s like if you took a ball and threw it in the air, instead of like coming back down again, the ball would move away and keep going up faster and faster and faster, which just doesn’t really seem to fit our world view at all. And so at first everyone said, oh, there’s just something wrong. Whoever did these observations just made a mistake. Blah, blah, blah. But then other teams independently verified that, yeah, this really seems to be happening to our best understanding of what we can see. And so we’re now working in this regime where we think that the universe is filled with something that we call dark energy. And the dark energy is kind of like, almost like an anti-gravity force that is pushing things away from one another with an increasing acceleration. And it’s a real mind bender. It just doesn’t seem to make a lot of sense. It doesn’t work on the physical scale of sitting in a room and thing go around here. But on the very, very largest scales, and probably on the very, very smallest scales, there’s this force that appears to be there, but we don’t quite understand it. And so a lot of our future mission work and ground base work is trying to think of ways that we can study this elusive dark energy. How can we really characterize it and fit it into our understanding of physics as we know it in the universe? It’s a very perplexing thing. And it’s going to keep astronomers and astrophysicists very busy for a decade or more, I would say.