The most recent Making Sense of Science Newsletter (available at http://www.wallingup.com/newsletters.php) sparked an online discussion with a Year 8 student. From it, I learned that there is not necessarily an age barrier to understanding advanced science topics, and that these challenging topics can supply the interest levels prerequisite to student engagement in the topic.
It also highlights the importance of integrating science with the humanities. This student had been reading the classic Ender's Game science fiction series by Orson Scott Card for his middle school English class (we both give it ***** five stars out of five).
I'd like to share the ensuing discussion with you.
Student: Aliens travelling to earth may have spent 1000's of years on a ship but the theory of reletivity would mean that they would not feel the ravages of time.
John: You are completely correct that aliens in a spacecraft moving near the speed of light would experience less time elapsed than on either their home world or destination planet. To them it might seem only a few years or even weeks. But to get going that fast requires such absurd quantities of energy it seems incredible that they would chose to do so.
So the aliens could survive the trip if they wanted to bad enough and had virtually unlimited energy to waste. But it would still take many hundreds of years of earth time for them to get here. They would have left on their journey at a time long before there were any radio signals to indicate that someone interesting lives here. We have only been sending out radio signals strong enough to be picked up in space for about the last 60 or 70 years, meaning that aliens living 70 light years away, if they are listening, would only now be aware of us. We can't expect to hear back from them for another 70 years, and we certainly can't expect them to drop by for many hundreds of years at least.
Student: Faster-than-light travel might be possible someday. Look at mobile phones! A few years ago people would have said they were impossible, too.
John: One thing to notice is that we did not exactly "discover" mobile phones, we invented them. The natural laws that allow them to operate were discovered more than a hundred years before.
But the computer technology that makes them work was invented step by step over the last 40 years. We did not discover any natural law that said "computers can do this" or "computers cannot do that," so we just kept trying new things.
There is a huge difference between technology and nature. Nature is the tree, and technology is the decorations. Technology must always follow Nature's rules, but Nature does not have to obey or allow technology. We do not discover technology, we invent it. Nature can only be discovered, and never re-invented to suit us. Technology only works if it is allowed by Nature.
Student: Just because we've never seen something doesn't mean it doesn't exist.
John: You are right about that. Don't make that mistake! If a guy says, "Dogs do not exist," because he has never seen one, he will be totally unprepared the first time a dog shows up and bites him on the bum.
We are not saying "there is no faster than light travel" merely because we have never seen it. We say there is no superluminous travel because we have discovered a natural law which says, "all speeds are less than the speed of light." Many experiments have proven that this law is true. They also prove that the opposite of this law is false. All experiments attempting to disprove this law have failed, too. It seems Nature is trying to tell us something, and the message is loud and clear.
We are not exactly in a room with the light turned off, speculating on what might be or might not be in it. We are also not like the guy who has never seen a dog before, jumping to a false conclusion. The light has been turned on. We have discovered that the faster you go the heavier you get until at the speed of light, you weigh infinity. It also takes infinity energy for matter to go that fast. By analogy, we have discovered dogs, and found that all dogs bark and poop. (and have sharp teeth). There is no need to speculate on the existence of dogs, or on the speed of light, because we are in possession of the facts.
Student: You cannot be certain that for example every element in existence has been discovered yet. New things might be discovered at any time.
John: I am particularly impressed with the way you think. Good job. And good on your teachers who cultivated your thinking skills. Your question is an important one: how can we be certain of what hasn't been discovered?
I'd like you to examine, if you would, all the whole numbers between 1 and 118. Are there any whole numbers missing? Are there any that we have not "discovered" yet? Are there any whole numbers in that range that are not known and still need to be invented?
If not, then there are also no new elements waiting to be discovered or invented either. We know of all elements as surely as we know about all the whole numbers from 1 to a million and beyond. Every element in the universe is a whole number of individual protons in a nucleus, with the same number of electrons hovering around it. To work out what possible elements might exist, simply write down all possible whole numbers. There aren't any missing.
This means that often it is specific knowledge of what does exist and how it is put together that enables us to make absolutely certain statements about what else might exist, and also things that cannot exist.
The only way to know the difference between what might yet be discovered and what will definitely never be discovered is to get as much understanding of the laws of Nature as you can. Things that those laws allow are possible at least in theory; things that the laws disallow are never possible no matter how hard we try or how much technology we get.
Student: Yes, but new laws are discovered which prove that the old laws were wrong.
John: Now who told you that? I'm sorry to say this is the first statement that is completely false. This has never happened, and people who say so are simply mistaken.
Newton's laws of physics replaced Aristotle's "laws". But those so-called laws were actually wrong to begin with, as any simple experiment could show. They were not really laws, but actually philosophical beliefs that were never tested in practice before they were written down. Galileo proved them to be wrong in his experiments. Finally, Newton worked out the simple laws of motion, forces, speed, mass and distance.
Einstein's laws of Relativity are sometimes said to prove Newton wrong, but the truth is that Relativity proves Newton was exactly right for all possible earthly speeds we encounter in everyday life. It is only speeds above 20 or 30 million meters per second that more information is needed.
Quantum mechanics is said to prove Newton was wrong, too. This deals with objects smaller than atoms, and it says they don't behave according to Newton's laws. But here too, Newton is proved right. Quantum mechanics tells us that large numbers of particles in a bunch together behave exactly as Newton would predict. Things even as tiny as a grain of sand obey Newton's laws perfectly, for all practical purposes. (How many atoms are in a grain of sand? See an older post in this blog.)
So a law that is proven experimentally does not stop being true, even when more information about totally different situations is uncovered.
Student: So the best way to invent stuff is to learn exactly about the laws of science so you can take advantage of them?
John: Good for you! Now you're on the fast-track! People who don't do what you suggest get bogged down forever basically re-proving the laws of Nature that are already known, and never invent anything useful. Do what Isaac Newton said, and Stand on the Shoulders of Giants to see farther than you would on your own legs. And Happy Newton's Birthday, 25 December!
Watch out for this kid. He's only 14 now, but he's going to make a difference.
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