Thanks to Google’s falling apples on January 4th, I discovered it was Newton’s birthday. After noticing, I decided that Newton was a must blog topic this week. I pondered presenting an argument for making his birthday a world wide holiday, just for the fun of making the argument. It seems that would be neglecting some issues that are more pressing to my heart. Dealing only with Newtons contributions to the world still leaves me with many possible topics. Lately, I have had discussions with friends and family about the standards of education in the world; thus I will present some light physics.

The Hubble Ultra Deep Field, with an added stick figure. Aimed at a dark spot in the sky the Hubble telescope took a long exposure resulting in this image. Using the original image, which was much larger than the one here, and image analysis 10,000 Galaxies can be counted! NASA/courtesy of nasaimages.org

One

Follow me in a thought experiment (or experience for those of you who don’t like to ‘experiment’). Envision that you have the power to survive in outer space and that you suddenly appear in the middle of outer space. This should be a peaceful idea, since it’s totally your choice to be there. You’re out in space with nothing to hold you up, or push you down, left, or right. You are not falling, right? You are in the middle of space! So what are you doing? Try to move. Can you walk or swim to move? Think about this for a second. It should be clear you can’t walk; there is nothing to walk on. Can you swim? No, there is nothing to swim through. You need something like water to pull yourself through. You need something to put your force onto in order to move. So if you suddenly appeared in outer space with no motion you would be stuck. Start the experiment over but this time imagine suddenly flying through space. Then ask yourself, how will you stop? Or turn? If you were, like an airplane, flying through the air you might come up with the idea of putting an arm out to the side to turn. But that only works because of the friction of your arm with the air. The force of the air on your arm. Sticking your arm out to turn in space does nothing; no air. So if you are not moving in outer space, you can’t start moving. If you are moving, you can’t stop.

Wow, that might be a nightmare experience for some. Others may be thinking “Kelly you’re silly, if this is true how would astronauts navigate space!” I am not going to argue with anyone. But I will point out that astronauts don’t ‘suddenly’ appear in space, they have to come from Earth and bring some tools to work in space.

The point to the thought experiment is to present Newton’s first law. Also known as the law of inertia is, in every day language:

An object in motion will stay in motion and an object at rest will stay at rest unless acted upon by an external force.

Two, Three?

I could continue down the list of Newton’s three laws, but I would like to see how this is received. Of course, ‘Newton’s laws’ may be googled to learn more. Or check out a text book on classical mechanics or physics at your local library ( I really hope there is one there!). One source for knowledge I really enjoy is MIT’s OpenCourseWare which you can find on itunes or youtube (or google it). The course relevant to Newton’s laws is 8.01 Physic I: Classical Mechanics. The video lectures are great!

This is the lecture on Newton’s laws. Some people may want to view the “reference frames” lecture that proceed it.