Jacob, now 4, wrote me an email asking "Why does the world spin?" Then he went on to suggest his own answer, "I think maybe the world spins because that's how the sun turns out the lights so we can go to bed and the universe can make a new day for Earth." Wow, such a good answer! I can't top that; even though the spinning turns out the light rather than the Sun, he has the correct idea. But, ...
There is a problem embedded in what I will call "big WHY" questions, and Jacob's question is in some ways one of those big WHY questions. Some would respond with words like "God made it that way", or some other platitude that provides no practical or usable information. It is exactly these WHY questions that science carefully avoids. The problem is that science can only answer questions such as:
- "How did the world start to spin?"
- "How does the world's spinning affect things?"
- "How does the world keep spinning?"
- "How ... etc. ?" You get the idea.
Science and scientists can figure out HOW stuff works and HOW it is made and HOW it changes over time, and HOW it does this, and HOW it does that, and HOW, and HOW, and HOW ... Science isn't so good at WHY. Not so good at:
- "WHY is there stuff at all?"
- "WHY does stuff follow these exact rules?"
- "WHY are we here to observe all this?"
Sure, science can answer "why" questions, but they are "little why" questions. Like "Why does it make a splash when I drop a rock in the pond?" If you think about it for a minute, you will realize that this is really a "how" question in disguise. Our language often makes it convenient to ask "why" when we really mean "how" -- "How does the rock cause the water to splash when I drop it in; and how is it that the rock drops when I let go; and how ..."
Those big WHY questions are the questions that religion "answers". Some [most, all, maybe every] big "R" religion has had a problem with science at one time or other. Their problem is that sometimes the WHYs that they have "answered" don't line up well with the HOWs that science discovers. And since they believed and had faith in their "answer", the truth is hard to swallow. It turns out that they had answered a "how" question with an explanation that seemed OK at the time, but was shown to be wrong when tested. They could believe it without proof, but when contradicted by reality they can only deny reality - argue that the facts are in fact not the facts, or explain that there is [must be] a higher law at work that we human mortals cannot [ever] understand.
Don't get me wrong, we need beliefs. There is a lot we don't understand, and even though we may not understand everything around us, we still have to get by from minute to minute; so we have to make assumptions about stuff. And we have to take it "on faith" that what we are doing will work out OK. BUT when we learn that our best guess was wrong, the smart ones will adjust quickly to the new old reality, and move on all the wiser - ready for the next "revelation".
So, "Why does the world spin?" As Jacob said, its spinning is how we have night and day.
The way it began spinning (i.e., how) is for the same reason that all the planets do, and on a grander scale the same way that all the planets go around the Sun in the same direction, and the way that the whole Milky Way galaxy spins too.
We and everything on Earth, and the Earth itself and the Sun and the Solar System are all made of the same stuff - stardust. When you take stardust and it gets all mixed up into the cosmic soup, after a while instead of going every which way, it settles down and begins to slowly spin all in the same direction. And the spinning makes it flatten out. Then after another long time, gravity pulls the dust closer and closer together into bigger and bigger lumps. Since the dust was spinning, the lumps spin too; and as the dust lumps get pulled tighter and tighter together by gravity they gather up more dust faster and they spin faster until they have gathered in all the nearby dust and they have become a big spinning ball - like the Earth or the Sun.
You can do this experiment to see how it starts:
(Mom should try this on her own first to perfect her lab technique.)
Sprinkle some pepper into a bowl of water and then stir it quickly in random mixed-up directions every which way. After a little while the water molecules will bump into each other enough times so that the motion will average out into a slow rotation one way or the other. The pepper will let you see the water's rotation. Try it several times stirring the water differently each time.
Of course this does not answer WHY. Jacob did not answer WHY either - smart boy. He answered a little "why" - a how. Every time we answer HOW, we push back the boundaries of WHY and we learn more, and we find evermore questions that beg to be answered. Why? I don't know; but I can explain how.
If everything we know is inside a big balloon, and everything we don't yet know is the air outside the balloon, then the rubber skin of the balloon represents all the questions we have and are trying to answer. Now every time we figure out an answer to one of our questions it is like putting another puff of air inside the balloon. This makes the rubber skin of the balloon stretch bigger; but the skin is all the questions we have, so every question we answer gives us more new questions that we didn't have before.
This is really why the world spins.
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