The speed of light and discovering

[Alex K]

I've been playing a lot of Elite recently where you can zip around solar systems beyond the speed of light. If you try to restrict your speed to below the speed of light it takes a really long time. If you stop and think about it, you realise just how big everything is. But conversely, it also struck me how slow the universe is.

Take two human bodies and information can be transmitted between each other seemingly instantaneously from the other side of the room. Yet light between two suns that far apart relative to their own sizes takes a long while to travel from one object to another.

But then the universe exists for billions of years rather than 80 years so taken over that time span maybe it isn't that slow?

You can play the following game: How old are things compared to the time light needs to travel across them? Let's compare me and the Milky Way

Let's approximate my size with 2 Meters (it's actually 1.92, but 2 will do). That's about 6.5 nanoseconds, or 1/(150 million) seconds.
I'm roughly 40 years old, that's about 1.3 billion seconds (jeez what have I done with all this time???). This means that light has travelled across my length a whopping 2*10^17 times during my lifetime. So I'll define my relative age as

A_Alex = 2*10^17.

Now, it's hard to define a definite age for our galaxy, but it's about as old as everything, so let's say 13 billion years. Let's say it's 150 000 lightyears big. That means the relative age of our galaxy is only

A_Milkyway = 9*10^4

What this means is that indeed, the Milky way so far is a much slower object than myself even if you take its great age into account. During the entire past life of our Galaxy, you could have only sent 90000 messages back and forth between its corners, versus 200 quadrillion between my head and toe in my lifetime.