There were two things I really liked in chapter 2.
First, the ether. I remember the ether from my Philosophy of Science class; I've always been fond of it. The physicists of the 19th century assumed that, just as sound moves through things like air or water, light must also move through something. They called that something "the ether" and worked diligently to find some evidence of its existence. Chapter 2 describes some of that painstaking work, and reveals that no evidence could be found.
Our prof asked us what this meant, and we said it meant that the ether didn't exist. He corrected us: you can't prove that something doesn't exist, he said, but it did prove that it didn't matter. If something has no observable effects, then it doesn't matter whether it exists or not.
The other thing I liked in this chapter was the discussion of the place of math in physics. I've always had some trouble with the idea that having the math come out right proves something about the universe. I particularly have trouble with the idea that having the math come out wrong allows us to posit random stuff (multiple universes, for example) to make the math come out right, and then behave as though it must actually exist in reality.
Isn't that sort of like deciding that the existence of an extra chair at the table proves that there must actually be another dinner guest?
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Omg ghost dinner parties!
ReplyDeleteI am loving this book for a couple of reasons. Each chapter definitely is full of new information to me, and so I am learning many new things.. but my little brain is going nuts with all the information as well. The thought trains rumble at 120mph and collide with each other. For instance, the thought that just because something isnt proven does not mean its not real is hard to wrap my head around. In addition to that thought, and going to your example, if it's existance is not proven and therefore it has no importance in its place in the universe, why do we search for it to begin with? Was it important before, and now doesn't matter in the slightest just b/c we can't prove it is there?
My brain may implode today...
In the case of the ether, I think it was more like it was such a weird idea that light waves could travel without any medium to travel through. There's no sound in a vacuum, because there's nothing for it to travel through, but light is okay with that. People were assuming that there must be something for the light to be in.
ReplyDeleteOnce they determined that there was no way to tell that the ether existed, they gave it up (although of course nowadays we've resurrected the word in ethernet).
But one of the things about the ether that I always found intriguing was the point that you made: we're not really saying that there isn't such a thing as the ether. We're saying that it doesn't affect anything, so it might as well not exist.
However, we've also said (or at least the authors have) that the movement of a plane cannot be discerned experimentally while you're in it. So perhaps the existence of the ether simply can't be discerned where we are.
Actually, I was on a plane this summer, knitting, and my yarn fell to the floor. We weren't allowed to take off our seat belts, so I just had to watch it roll all the way to the back of the plane. Everyone watched it roll, in fact. Silently. Deeply embarrassing, and indicative of movement on the part of the plane, right?
The idea of unproven things still existing isn't the hard part of this, so much as the idea that concepts that may be true don't matter.
ReplyDeleteI believe that there are things out there I do not know yet which still exist. My ignorance of them does not somehow cause them to not be real.
Yet, when considering hypotheses and things that may exist, then by their very nature I feel they are made important. If we just said "oh it doesn't matter" everytime we couldn't definitively prove something then we'd surely not be as far as we are today.
Something terribly boring about saying "Hm. Can't prove that, so it really doesn't matter anyway. Let's go get a beer!"
I'm still working on Chapter 3. But it seems to me that they have skipped one basic, important concept. That is "what is light?" It isn't the same as an object. If we can't ever catch up to it, it seems that its movement is fundamentally different than the movement of an object. Is it really moving? I guess I need to go back over the part where they describe determining the speed of light.
ReplyDeleteAre we ready for Chapter 3, then?
ReplyDeleteI think there is a terminology issue regarding movement. Movement and travel are two seperate concepts and can't really be used interchangably.
ReplyDeleteExcellent point, Josepha. Unless we're talking about lasers, light kind of spreads out and fills things up, rather than traveling like a ball being thrown. Sound, too, actually goes from one place (source of sound) to another (eardrum of hearer) but it travels quaquaversally and can reach lots of places more or less simultaneously, like all the people in a concert hall.
ReplyDeleteI'm finding it confusing to think about this. However, if the movement of light is different in its essence from the movement of other stuff, then we may not be using "speed" in the same way when we talk about it and about other things.
Janet, did you reach any conclusions?
Janet, I think you're right that they should have spent at least a few paragraphs describing the fundamentals of light. The omission, however, probably means that we really dont need to focus on it very heavily. Light has the properties of both a particle and a wave. But then again, so does all other energy and matter. It's just easier for us to observe the particle properties of most things with any sizable mass. If you get down to a small enough scale, everything is made of the same "stuff" (That's more along the lines of String Theory though, which is still fairly controversial as far as I know). Because of that, I dont think we need to treat light differently than other objects in this context.
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