In this first chapter our authors set out to prove to us that there is no such thing as absolute motion. Meaning, of course, that all things are moving so there is no single stationary thing with which we may prove we have moved. Using the Law of Non-contradiction they also sort of address the issue of absolute time, though in nowhere near the detail used when dealing with space and motion.
As I mentioned before, I have a lot of trouble coming to terms with the idea of an unending void, yet I found that I have no trouble whatsoever with the idea that everything is orbiting around something else with no clear center at all. It is possible that this is just an idea to which I have become accustomed thanks to so many hours of public education, but in truth it seems reasonable.
Rational, even.
That leads me, then, to this question: If all motion is relative, then what aspect (if any) can be considered absolute? Distance? Speed? Though is speed specifically a relationship between time and distance... keeping in mind that time is apparently relative, as well?
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Well, I think time is in chapter 2...
ReplyDeleteBut they use the example in chapter 1 of the person on an airplane (Einstein used a train, natch), who sets down a book and a drink and goes to see a friend elsewhere on the plane and then goes back to the same place, where the book and drink are waiting. But relative to someone on the ground, the book and drink have traveled miles.
But the person on the ground has also traveled miles, what with the rotation of the earth. So a person on the sun (feeling doubtless very uncomfortable) might say that the person on the earth has moved.
But the sun also is moving in space, so actually no one is standing still.
How then can we measure the movement of the person on the plane? Since there is nothing in the universe that is actually not moving, we can't measure the placement or the movement of anything in absolute terms.
We can only say where they are or where they've moved to relative to something else.
And yet -- and I really like this part -- there is no way for anyone on the plane to prove that movement is taking place.
If we drop a ball, it'll fall straight down. On the earth, too. If the observer on the earth drops a ball, it falls straight down as though no movement is taking place.
Ditto for the person on the sun.
So no one in this scenario is standing still, we know. And also, no one -- according to all possible observation and testing -- is moving.
Except for the whole arriving at another place part of the scenario. Which, once again, defines position and movement only relative to something else.
The most interesting part about this chapter, to me, is that the only thing that has changed is the way that I think about how i move and things near me are moving. Yet.. I suddenly feel much more chaotic. Things seem much more simple if I look at a chair as holding still and I am as well.. but we're not. Its only in how I think about it though.
ReplyDeleteNothing has actually changed.. but in my mind's eye I'm suddenly in a world much like Disney's illustration of Alice falling down the rabbit hole.
That's great. I'm seeing things that way, too, now that you've pointed it out. Here we all are flitting around through space, largely in circular patterns, meeting up with things occasionally.
ReplyDeleteBeethoven or Mozart for the soundtrack?
Death Cab for Cutie would be my soundtrack.
ReplyDeleteThey have that floating feather type of sound :)
The part about not trusting our intuition strikes me as interesting. While it is great to be able to prove or disprove theories through testing hypotheses, it seems rather flippant to dismiss such an idea by saying "it simply doesn't matter either way." There are a lot of things that I am very interested in that can't be proved by scientific experimentation. I suppose those questions are addressed by philosophers.
ReplyDeleteBut where does intuition come from, if not from previous experimentation? I remember realizing that my two small kids in the back seat needed to learn that if you throw something out of your seat, it doesn't magically come back. They learned that. I have learned that it's best to not go to work via a certain route if I leave between 7:45 and 8:00.
To me the correct application of intuition is in recognizing and identifying the differences between the circumstances under which the 'lesson' was learned and the current circumstances.
My kids learned that sometimes, when someone else was in the car, things did magically come back. I have learned that if school isn't in session, that route to work is fine.
So perhaps it is not the absence of intuition so much as it is recognizing the limits of its applicaiton.
I think that's one of the really interesting things about physics, though: if we didn't behave as though our intuitions were correct and instead went by what can be proven by experimentation (and math), it would be very difficult to function at all.
ReplyDeleteOur perceptions of the world are part of what makes it possible for us to live here, however far they are from ultimate physical reality.
Janet, I was intrigued by the idea that it "didn't matter either way" myself. I agree with Rebecca when she says that our perceptions, provable or not, are what makes it possible for us to live here.
ReplyDeleteSurely it's at least important to have some awareness of these ideas or we wouldn't be reading this book, right?
I'm reminded of when William did the Trebuchet Physics workshop and then told us "We could have done it without the physics."
ReplyDeleteWe don't really have to know that our intuitions about the world are inaccurate, because that fact doesn't affect our behavior.
But it's sort of like living your life without God. If there is a God, then you can't actually live your life without Him even if you think you're doing so. Equally, our not knowing about (or not caring about) the physical nature of the universe doesn't really mean that we're doing it without the physics -- we just don't know about it.
The subtitle of the book is "and why you should care," and it'll be interesting to see what arguments the authors offer.
Not sure I'm getting why God keeps coming up :)
ReplyDeleteReading the next few chapters while i travel this week.. MIA for a bit but will catch up when I get home! :)
Found a picture of the Ptolomeic map on Wikipedia. I'm not really seeing the off-center rotating wheels and spinning spheres. There must be more somewhere.
ReplyDeleteSeems to me this is really the concept of "knowing what you know." In other words, when you know what to expect, understanding why you expect that. Being able to explain the cause and effect. That's a deeper level of knowledge than just relying on intuition and making a prediction. It's knowing why, being able to test that, and being able to apply the concepts in different circumstances.
I am always intrigued by the fact that people really do have diverse passions. Some are compelled to explain the movement of planets. To me, I'm curious, but I feel no impetus to chart it and figure out the orbits of the planets.
I understand why comments about god will be coming up. If you believe in some deity that has control or influence over your life as a whole, that deity will likely permeate your thoughts on almost any subject. Either way, I can see the analogy. We are bound by the laws of physics even if we arent aware of them, just as we would be bound to live in a world with a god if that god did exist, even if we didnt believe in that god. Belief in a truth is not required for the validity of that truth. Or in words that are not my own, "Reality is that which, when you stop believing it, doesn't go away."
ReplyDeleteBack to the book...
Since infinity is such a hard concept to grasp, I can't help but to think/hope that someday we will discover an absolute framework within which our universe is set. Until that time, we get to see just how creative our brightest minds have been.
That's exactly what I meant, Darin - it doesn't matter whether we believe it or not.
ReplyDeleteAnd, in fact, as I sit here on an apparently stable chair in front of my apparently unmoving computer, confidently allowing a full cup of tea to sit on a seemingly solid desktop, it requires faith on my part to believe that it's all a collection of molecules whizzing around, on a planet which is itself whizzing around in space, which is also moving.
Wow, that was a long sentence.
Janet, I figure the orrery is the thing to have in mind there, rather than a map.