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Right so the speed of light is 3 x 10 ^ 8 Metres per Second, which is this number here,
quite a big number. And that is obviously the speed at which light travels. But--
--Yep, that, is the speed. How are you?
--Who are you, sorry?
--I'm Mr Physics. See that, that's an atom. Beautiful, I mess with these, all the time.
--What are you doing, what are you doing?
--Nothing. Just here to observe.
--Right, okay, alright. So, I'm talking about the speed of light.
--Oh yeah, jolly good. --You know this. So, supposing we're in a
train. --Yeah, which goes about, what, 80 miles an
hour. Pretty slow. --It's a special train. Alright, because if
we travel in a circle we can reach -- -- No you can't --
-- very close -- -- no, very close.
-- We can reach very close to the speed of light. We can't reach the speed of light because...
-- Because that's impossible. Only light can travel at the speed of light, I understand
that point. --Otherwise things will be too confusing,
I don't want that to happen. See that, light, that's fast. That's your top speed.
--Alright, I'm trying to talk to the, right okay. So, we're going on this train, right,
99% of the speed of light. 99.99% of the speed of light. But we're not actually goin- but
we're not actually going at the speed of light, so we're safe from you, aren't we?
Right, how about this then, how about this? - We're on the train, 99.99% of the speed
of light, somebody, on the train, runs down the middle.
-- Won't make any difference. -- Yes!
-- No it wouldn't. -- It adds to the forward moment-- no it wouldn't!
-- momentum of the train. -- Train slows down.
--Are you suggesting that a train, going 99.99% of the speed of light: you are going to slow
down the train, so you're slowing down time inside the train? -- With my right hand.
You, Physics have slowed down the inside of the train, making everything slower, which
means the people on the inside of the train are going to be travelling forward in time,
because everything on the outside is going to be faster than them. Right. Travelling
at 90% of the speed of light, on this train means that 2 hours inside the train is 1 hour
outside - is that right? --Yes, yes roughly that.
--90% of the speed of light. Okay, that makes sense. Right, okay so, if we go at 99% of
the speed of light - really, really close to the speed of light - and you've slowed
down the train that means that one day inside the train will be one year on the outside.
--Yeah, I spose. --So we can travel forward in time?
--Yeah, but not faster than the speed of light. Glad we got that understood.
So, My Physics, what just goes on inside your head?
Nothing.