Today, 21st October 2015, the day super fans of the movie trilogy of the late 1980's have long waited for. Having been a small child back in 1989 when BTTF2 came out, I remember watching the movies on TV a few years later and re-watching them countless times since (my husband is a massive fan and in fact we always have them recorded on the digi box!) In fact it was my lovely husband who text me excitedly at 04:30am to remind me of this auspicious date - thanks sweetie, forgot the time difference I think ;-)
Right, so now you're all thinking, what the hec has BTTF got to do with LISA Pathfinder... well the link may no be quite so tenuous as you might think...
Time Travel.
The main theme of the BTTF movies of course. Now then as most A level physics students will tell you, time travel to the future is theoretically possible, if you can get up close toward the speed of light, in theory as predicted by Einstein's special theory of relativity you could travel forward in time just like Marty and Doc Brown do in the film when they travel from 1985 to 2015. But back in time, like travelling from 1985 back to 1955, now thats a little more tricky. Why, well because to go back in time you need to travel at or beyond the speed of light and as Special Relativity and E=MC^2 tells us, as you get closer to light speed, your mass increases meaing you slow down and need more energy to speed up again.
So you need a cheat, something that can enable you to manipulate the fabric of space-time to enable you to travel back in time. Enter Einstein's General Relativity and, you guessed it those gravitational waves that we're hoping LISA Pathfinder will help demonstrate the technology needed to enable us to build a full scale in orbit graviational wave detector. Einstein's theory, that space and time are not separate but intrinsically linked as space-time. Gravitational waves are then ripples in space-time caused by the rapid motion of massive objects like colliding Black Holes. Wormholes theoretically could exists where the curvature of space-time somehow creates a tunnel connecting different regions of space-time that in a flat universe would be very great disances apart. This could in theory mean it would be possible to travel via a wormhole to an area of space-time that is either very far away in distance, or in time, perhaps even back in time without having to travel at greater than light speed.
So while some of the predictions made in BTTF 2 about 2015 have not quite come to fruition, our knowlegde and understanding of the universe will hopefully soon start to be greatly expanded and if/when gravitational waves are detected in space, science fiction might be a step closer to becoming science fact! Happy BTTF day all.
Picture credit: http://m.space.com/30829-scientists-pursue-time-travel-via-wormhole.html
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