We've talked about some of the largest things in the universe here on SciShow Space
From planets to galaxies to super-voids more then a billion light years across
And it's sometimes hard or impossible to actually understand this gigantic things
because humans didn't evolve to think that way
But by taking advantage of the ways our brains map out our environments
We can get around those limits and maybe start to understand, say, how far it is to the nearest star, Proxima Centauri
See, lots of animals including humans create mental maps of their environments
As we evolved, our mental maps included things like where resources were, where predators lived and nearby water sources
This days your map is probably the reason you can stumble to the bathroom in the middle of the night
instead of walking straight into a wall or something
Thing is this mental maps are what physicists and astronomers like to call "medium-sized" things
Houses or even mountains but not like extreme sizes
of atoms or solar systems
They also depend on structure
Meaning that the number of objects or landmarks between two points
changes our understanding of the distance between them
In one study researchers asked people to look at a page with a bunch of points on it and estimate how far apart pairs of them were
They found that the more points,
what the experimenters called "clutter",
there were between the two points in question the more distance people
thought there were between them
Other experiments have shown that our mental maps of cities
even the ones that we grew up in work in similar ways
Our understanding of the distance between two points is affected
by what's in between
This works really well in a forest or in a city
but is not so good at mapping something like outer space
In space most objects are anything but medium sized
and are separated by huge expenses of nothing
Like real actual nothing
It's too big and too spread out for our brains
But there is something that we can do about it
Put the huge numbers in terms of smaller, more understandable units
Take the distance to Proxima Centauri for example
4.2 light years
Meaning that it would take 4.2 years to get there if you were traveling at the speed of light
Most people over the age of 4 can probably understand how long 4.2 years is
But the speed of light - over a billion km an hour - just registers in our brains as "big number"
To really figure out how big that gap is we need to put both factors
Time and speed
into more understandable terms
The international space station orbits the earth at more than 27,000 km an hour
If you are going that quickly straight up from the surface of earth
How long would it take you to get to Proxima Centauri
Well it would take you about 13 seconds to leave earth's atmosphere
and 13 hours later you'd pass the moon
226 days after leaving earth you'd pass the sun
31 years later you'd pass the orbit of everyone's favorite non-planet, Pluto
even at its farthest distance from earth
But 31 years is still a pretty understandable amount of travel time
Proxima Centauri can't be that much farther, can it?
Oh it can! And it is!
Going as fast as the ISS it would take 164,00 years to get to Proxima Centauri
What was happening here on earth 164,000 years ago?
Well, was a while back but at least the homo-sapiens were around
So if you're having trouble picturing things with huge or tiny measurements
It might help to put them in terms of something more relatable
Like the diameter of the observable universe
About 10 to the 26th or a hundred trillion trillion meters
Which just happens to be the number of human hairs
that you would need to cover the entire surface of earth
to a very itchy depth of one meter
Numbers. You gotta love 'em!
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