Don’t be surprised if Carrie Fisher’s Princess Leia looks a little older than her brother Luke when the Star Wars twins return to cinema screens later this year: scientists at the University of Leicester say that by now she actually has about two years on him.
And it’s all thanks to Einstein’s Theory of Relativity (no pun intended).
For those of you who aren’t familiar with the old E = mc 2 jargon, Einstein’s theory says that if you move fast enough through space, the observations that you make about space and time differ somewhat from the observations of other people, who are moving at different speeds.
That means, for example, that the time on a ship which is moving very quickly appears to pass slower than on Earth. And they call this little phenomenon time dilation.
The students from the university’s Department of Physics and Astronomy decided to carry out a study to figure out how time dilation might have affected Luke and Leia, based on their journeys to Cloud City in Empire Strikes Back.
Leia starts her journey in the neighbouring system of Anoat and arrives at Cloud City in around 6.72 hours, while Luke’s journey from Dagobah, in a star system much further away, takes around one week.
The Millennium Falcon also packs larger and probably more powerful engines than Luke’s X-Wing fighter, so the students presumed that it would travel at a much faster speed, giving Leia’s journey a time dilation of 62.6 days.
Meanwhile Luke’s journey results in a time dilation of 700.8 days, making him roughly 683.2 days younger than his sister by the time they both arrive at their destination.
“While it is not demonstrated in the film, the twins will actually have aged very differently due to their extensive travelling at speeds close to that of light,” the article in the Journal of Physics Special Topics says. “Despite Luke’s journey being twenty five times longer than Leia’s, the time dilation he experienced was only around ten times larger. This shows that miniscule changes in relativistic speeds have significant effects on the dilation observed.”
Curiouser and curiouser, but stick with us. There’s more.
A second experiment looked at how gravity would affect the passing of time. That’s gravitational dilation, to use the correct scientific terms. This scenario questioned how long Luke would have to orbit the planet Bespin, on which Cloud City floats, to catch up with his sister.
“To compare the difference between relative velocity and gravitational time dilation we attempted to calculate the time Luke would have to orbit the gas giant in order to correct for the time dilation experienced in scenario one, and become the same age again” the paper says.
“The difference in time dilation experienced by Leia and Luke was calculated to be 1.96×10-7 seconds for every second of proper time. This results in time in Luke’s reference frame ticking very slightly faster which means that for Luke to become the same age as Leia he would have to orbit for 9.77×106 years.”
That means that for Luke to become the same age as his sister he’d have to orbit Bespin for 9.77 MILLION years.
We’re going to need a few more sequels…