I'm in an airplane bathroom aboard a 777 somewhere over the mid-Atlantic.
It's a long flight and this is a strange place to film a video, but
it is the perfect place to tell you about relativity.
Specifically, that Einstein was not the first person to have ideas about relativity.
Centuries earlier, Galileo came up with the concept of what now is called "Galilean relativity,"
which is the more basic idea that if you're in – well, he would have been thinking about something like
the hold of a sailing ship – but if you're in an airplane bathroom, there is no physics experiment
you can do that will tell you how fast you are going.
You could be going 500 mph, as we are,
you could be going at 9/10 the speed of light, magically, given you'd actually burn up to a cinder,
you could be stopped, just hovering in some kind of simulator at this altitude, and
there is no way you could tell, because, well, you can't see what you're going relative to.
And that idea, that there is no privileged frame of reference, was built upon by Einstein,
who realized that if you are in an airplane bathroom going at 9/10 the speed of light
and you turn the headlights of the plane on, well,
the pilot of the plane would see the light go at the speed of light and an observer would
also see it going at the speed of light, that crucial idea
is where all of relativity comes from, the idea that there is no privileged frame of reference.
But that was Galileo's idea centuries earlier.
And that is something you might not have known.
And here's another thing. If I was clever, if I was really clever, then what I would do
is film this in a completely fake airplane bathroom and now, to prove my point,
I would have the walls fall away...
I've got about 5 hours left in this flight.
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