Without apologies, I will borrow Simplicio, a character from Galileo’s work for a while, in order to have a small dialogue.
Simplicio- So what is this thing called physics all about?
D.B.- Physics is the study of nature. We try to unravel the mysteries of nature, and with that underestanding we can make predictions about the future.
Simplicio- You mean you look at the sky, you make guesses and look into a crystal ball?
D.B.- That is Astrology. That is not considered a science.
Simplicio- Soooo, you can predict the future? Hmmm? Go ahead make a physics prediction for what will happen tomorrow.
D.B.- The sun will rise tomorrow.
Simplicio- That’s it? I could have predicted that as well.
D.B.- How can you be so sure?
Simplicio- It happens every day. Therefore, it will happen tomorrow.
D.B.- But how do you know that the sun will be there tomorrow? Isn’t it possible that the sun would decide that it is tired of shining on, and that it would decide to take a vacation?
Simplicio- I never thought about that. Now I’m getting scared. However, if the world is just, that can not happen.
D.B.- So you are trying to tell me that your morality requires that the sun will rise tomorrow?
Simplicio- Most certainly…. Hey there, wait a minute! I have the suspicion that you are trying to make a fool out of me! You did the prediction, and now I’m the one justifying it? I smell a rat! If you’re so clever, then tell me how you are so certain that the sun will rise tomorrow.
D.B.- The earth is a massive body spinning about itself. It carries quite a bit of angular momentum. Seeing as there is only negligible torque applied to the earth, there is no mechanical force in action that will prevent it from spinning or slow it down to a halt in the interval of a day.
Simplicio- So… let me assume that what you said is correct… what about the sun being there?
D.B. – The sun is a big fusion reactor. We understand the laws of physics of how the sun works well enough to know that after many billions years of operation, it still has fuel for many biliion years to go before anything dramatic can happen.
Simplicio- That sounded like quite a mouthful. By the way, I hear that this evil machine called the Large Hadron Collider will be turned on tomorrow and that a black hole that will swallow the earth is going to be made there. What do you have to say about that?
D.B.- That will not happen at all.
Simplicio- How can you be so sure?
D.B.- I am as sure about that as about the fact that the sun will rise tomorrow. And if you have any lingering doubts, go check this website * to verify if the earth has been destroyed by the LHC yet.
*Spotted at Asymptotia.