Relativity in a Canoe

The world moves around the canoe.
The world moves around the canoe.

Perhaps not surprisingly, my middle school students have a difficult time wrapping their heads around the idea of multiple frames of reference. We were in a canoe on the Current River and I asked the student paddling in the rear of the boat to look at me and answer the question, “Are we in the canoe moving, or are we steady in one spot and everything around us moving?”

This resulted in some serious cognitive processing. And she still has not gotten back to me with an answer.

Another student, faced with the same question, thought it over overnight and concluded that it was a riddle. He figured the correct answer was that the canoe was moving and the land was still. I asked him to think about it a little more (because he was only half right).

Interestingly enough, I’ll be teaching my Advanced Physics class this block, and the first chapter has a neat little section on coordinate systems. I’m curious to see if the 11th and 12th graders have an easier time with the concept.

The canoe moves.
The canoe moves.

The Visible Universe

Everything depends on your point of view — more or less. Our picture of the universe has changed in the last 60 years as telescope technology has improved. Popsci has a great interactive visualization showing how much more we can see now.

Notice that in this picture, the Earth is at the center of the universe (the Sun is a little way off to the middle lower left). After all, we’re looking at the universe from the Earth, not the other way around.

The universe as it appeared in 1950, compared to what we can see now (2011). Image from Popsci.com