How Big Are Things? 
I hope to make it easy for you to know how big things are.
Everything from atoms to galaxies.
The idea is to have rooms with different magnifications.
In one room, you are Godzilla,
and people are the size of ants.
In the next room, the world looks like a road map.
And in the room after that,
the Earth is a blue-white marble, floating in space.
Just ten rooms get you from your teeny tiny atoms
to our really BIG Milky Way galaxy.
The next neat thing is that you already have a feel for how big
some things are.
If I ask you, "How big is a can of soda?", you already know!
You are not going to think it is as big as your bathtub... no way.
And you are not going to think a can is as small as your finger.
You've held soda cans, and you know how big they are.
So we are going to do the same thing with buildings.
And with planets. And bacteria. And lots of other stuff. :)
We can even do some of them for real, making models we can really hold.
(Like a little Statue of Liberty. Or a virus that looks like a
baseball with spikes).
So, that is what I'd like this site to do for you.
To help you get a feel for the sizes of everything.
Here is the Welcome page.
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Background / Vision
This site was inspired by
Cosmic View
and Powers of Ten
(another,
list).
They are nifty, but have some limitations. I have found them hard
to remember ("Was the Earth 10^6 or 10^7 meters?"). And it is
not easy to compare objects spread over multiple pages ("What is
the relative size of Moon and Sun?"). And few objects are
presented, as the emphasis is on a broad-brush sketch of scale,
rather than on the sizes of a rich set of objects. And finally,
precision is hard to come by ("The Earth is what times
10^7 meters? Is it a big 10^7 or a small 10^7?").
So "Powers of Ten" is a terrific introduction to scale,
but only gets you so far. This site attempts to pick up where
"Powers of Ten" leaves off.
"How Big Are Things?" tries to make size something
you can remember, use, and optionally
calculate with. This site will have succeeded if watching the
news, or talking with friends, you can quickly and easily figure
out the rough size of anything physical. And hearing a size
("100,000 acres are burning in Arizona"), you have a feel for
what it means. Whether this is something this site can really accomplish,
is not yet clear. And it will work better for some folks than for
others (eg, it works best if one thinks spatially, rather than say
symbolically). But it is a start.
The approach taken is to break Powers of Ten into chunks of 3
orders-of-magnitude (each chunk is 1000x bigger/smaller then it's
neighbors). Having 10 chunks is more manageable than having 30
pages. Each chunk is treated as 1, 10, 100, thru 1000,
whatever-meters. So, for example, there is a 1/10/100/1000
kilo-meter chunk. Then each chunk is made tangible by treating it
as a "room". In the "kilometer room", 1/10/100/1000 kilometer
objects are 1/10/100/1000 millimeters big. Then, the rooms
are filled with objects. For instance, in the "Megameter room",
the Earth (13 Megameter big) is a blue marble (13 mm big).
Jupiter is a striped softball. And the Sun is a big white
person-high ball. This leverages our everyday ability to remember
the rough size of things we handle. Then, we can
draw/print/craft/gather appropriately sized models of objects.
For instance, I have a real Earth-sized marble. And a cup of red
blood cell sized M&M candies. We can decorate our real rooms
to look like these whatever-meter rooms. And there we can stop.
With rooms full of pretty objects. The universe at your finger
tips. Everything from atoms to galaxies. No numbers. Perfectly
suitable for kindergarten kids.
But we can also take it one step further. Numbers are easy to
come by. Easiest are the orders-of-magnitude ("1, 10, 100, and
1000 kilometers are ten to the 3, 4, 5 and 6 meters"). You only
need to be able to add and subtract simple numbers. You can even
do
it on your fingers. And then, if/when you do want greater
precision, you can easily get it. On these web pages, you can
just count squares on the graph paper background. And you can measure
the models with a ruler. And then, later,
as you become familiar with the sizes of everyday objects
("About how many millimeters long is your finger?"), you can
often do it from memory. For example, the blue Earth marble,
is, well, marble-sized. So more than 10 mm but less than 20 mm.
So just by remembering that the Earth is a pretty blue marble, I know
its diameter to within better than 50%.
So, that is the idea. That anyone can easily get a feel for
how big things are. And then, with surprisingly little work,
develop a rich and powerful quantitative mastery of size.
A strawman provocative statement might go like this: By
early elementary school, people can have encountered everything
from atoms to galaxies, view them as real tangible objects, and
have a feel for their sizes. Late elementary school students can
be doing length, area, volume, and Fermi problems, dealing with
any object the physical world has to offer. This combination of
familiarity with the physical universe, and adeptness at
approximate quantitative reasoning, provide an interesting
complementary/alternate approach to science education. There is
no excuse for the current state affairs, in which engineering and
science graduate students have only the most tenuous grasp of the
magnitudes of even the simplest properties they have spent
years studying. And finally, a familiarity with the rough
sizes of everything physical is a prerequisite of basic literacy.
<Flame off>. How's that for an eyebrow raiser. :)
Comments encouraged - Mitchell Charity <[email protected]>
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