GWPAC faculty member Geoffrey Lovelace introduced students at Santiago Canyon College (SCC) to colliding black holes and time travel May 15. 
 
The presentation was arranged by SCC student Haroon Khan, an electrical engineering major who worked in Geoffrey's research group in the 2013 STEM^2 Summer Research Experience and who will be transferring to CSUF this fall.
 
Speaking to a packed auditorium in SCC's brand new humanities building, Geoffrey started out by talking about what black holes are like and how colliding black holes send out gravitational waves, which are ripples of warped space and time. At CSUF, Geoffrey and his students in GWPAC use computer simulations to model colliding black holes and the gravitational waves they send out across the universe.
 
During the second half of the talk, Geoffrey talked about time travel. Traveling forward in time (at least by several billionths of a second) turns out to be possible, thanks to the laws of special and general relativity. These laws of nature say that your time flows at different rates, depending on your motion and on how close you are to a massive object (such as the earth, a black hole, etc.). In fact, the Global Positioning System (GPS) has to account for the different rates that time flows in order to function. 
 
To wrap up the talk, Geoffrey discussed work done by Kip Thorne and two of his students in the 1990s, regarding backwards time travel. Is it possible to go back in time and change the future? To find out, they explored what happens when a billiard ball enters a time machine. They wondered, could the ball emerge in the past at just the right moment to collide with itself, preventing itself from going back in time? They found, for any initial conditions they could think of, that there was always at least one self-consistent future that satisfied the laws of physics.