At the Borders of GED Science - light, time, pigs


I recall a U.K. itinerant cosmology meeting in which Neil Turok, then one of the main opponents of inflation, got into a heated argument with someone who insisted that inflation was the only known solution to the horizon and flatness problems. Neil... retorted... suppose "something," some principle fell into action, which ensured that only a universe as symmetric as possible would be allowed. No sooner had Neil finished... than Mark Hindmarsh, sitting half asleep next to Neil, suddenly said, "Well, in that case, shouldn't the universe be Minkowski space-time?"

There was a one-second silence... and then everyone burst out laughing, including me.

Yeah. Me, too. That Neil and Mark. What a pair. Minkowski space-time. Too funny.

*sigh*

So, let me close up this science / speed of light thing.

I made it to page 100 of Magueijo's book. But, truthfully, I haven't understood a thing since page 64. There are starting to be signs that Magueijo's editor also lost his or her way, and maybe just left the building altogether. Since I've got other books waiting to be started, several more relevant to the core of my responsibilities, I'm going to put this one away for now.

It's okay, though. It was fun for a while.



It's okay, too, because I'm well beyond where I need to be to talk learners through the astrophysics needed for the current Science GED.

Actually, interestingly, learners are telling me that the current Science GED isn't that bad. And they're getting the high scores to prove it.

On the other hand, the Reading (Lit.) GED and Social Studies GED are giving them problems. Why? They say they're running out of time. They say it's too hard to find the answers because the passages are so long. They say there's just too much to read.

The Science test seems, typically, to employ charts, diagrams, and short passages - less than 100 words. A passage in Social Studies or Reading might be five times that length.

So what does that say about their needs? About how I can best support them?

Background knowledge is still important, yes. But this thing about dealing with larger chunks of text.... Well, I'm making an extra effort to have a variety of novellas and short-chapter nonfiction works in the room this year. But, other than encouraging more reading, I don't know how to help them increase their speed and accuracy.

So, anyway, those were my thoughts last week.

Then, I noticed a story in the Independent about scientists confirming that time passes more quickly at a higher altitude.


According to the story, these guys placed super-accurate, super-sensitive atomic clocks at different heights, and the clocks registered a difference too fine to be perceived by humans.

According to the Science Magazine podcast of 24 September 2010, the way the scientists measured the "gravitational potential" - what we'd call the influence of gravity - was to assume (!)... Look, here's what the lead researcher said:

Yeah. Well, the gravitational potential is, well, if you had the same height most likely you’re at the same gravitational potential. We know our clocks, although they are in different labs, the gravity field should be pretty uniform for these two clocks, so we just use the height difference to derive the difference in the gravitational potential. And the measurement, what we did was we simply just lift up the whole apparatus for one of the clock, and we just use a hydraulic jack to raise it up by 33 centimeters. And then, the two clocks – just by comparing their frequencies – we see the tiny shift due to this height change. So, that’s how we measure gravitational potential difference with these two accurate clocks.
The clocks are in two different rooms. But the effect of gravity should be pretty uniform. Yep. PrETty darn close. Then, these guys say, "by getting one of the clocks a bit higher, just a bit more than a foot higher, we can see that it’s ticking a bit faster."

Oo...kay. It's ticking faster. Why? Because the clock speeds up?

Nope. Podcast host Robert Frederick says it's because time speeds up: "Chin-wen Chou and colleagues have measured time dilating...."

Ah.


Maybe you can already see the source of my frustration. The only way anyone can say something varies is if they measure it against something that's not varying.

Suppose I measure my pencil and my pen, and discover that one is longer than the other. Suppose I am using a standard, unvarying device for taking a measurement, like a ruler which marks off units of fixed distances, like centimeters.

Now, suppose I get all fourth year philosophy nerd, and say there's another possibility: I could assert that my pen and my pencil are invariably the same length, and that centimeters are relative depending on what we lay them next to. When I lay the the ruler along side my pen, I demonstrate that my pen lengthens centimeters, requiring fewer of them. On the other hand, laying the same ruler beside my pencil shortens centimeters, which is why the pencil uses up more of them.

Pretty silly, eh?

Well, what these geniuses are saying is that gravity (or height or distance from the earth's core or something) can affect time... but not, remarkably, the workings and accuracy of atomic clocks?

Did you get that? Atomic clocks are a universal absolute. (Even when they're located in different rooms.) Space and time - or, rather, space-time - is affected by gravity. But the clocks we build in 2010 are immune.

And, yeah, okay... What the hell... I guess the scientists are right. I mean, when the clock in my kitchen loses time relative to the clock in my bedroom, I almost never think "I guess time is relative" or "there's that ol' gravity at work again." But I'm, you know, no Einstein.

And it's all good anyway, because I've already decided to leave this stuff behind.


So. (Deep breath.) It's a rainy afternoon. Everybody's reading: fiction, non-fiction, whatever. I'm tucked into a short history of New Brunswick I hadn't read before. It's warm and comfortable, and a few heads start to loll. You know how it is.

So I spring to my feet, erase the white board, and ask, "Science or Social Studies?"

Science, they say.

I draw a half-sun and we fill in the names of the planets. Somebody wants to know the difference between a comet and an asteroid, and so we're off. We talk seasons and why the days are getting shorter where we live. We talk about the northern lights and magnets. Space travel comes up, and I share something I'd heard lately - that even traveling at the speed of light, much faster than our chemically fueled rockets, it would take more than a thousand years to get to the next solar system (and it's not even very interesting). We can explore our own backyard, but we're not getting any further in the foreseeable future. And somebody asks, "What is the speed of light?" And I, sinner that I am, quote forth "Three hundred thousand kilometers per second." And they talk about that - about light leaving distant places long ago and only getting here now.

And somebody asks, "Does it matter where... I mean, does it matter, like, how high you are? Does that change the speed of light?" and "Is time the same all over?"

And I don't know what happened to my face, or if I swore aloud or only thought it. But they all stopped, their cherub faces turned to me.

And then I glanced at the clock and saw it was time for class to end.

Go home, I said. We'll talk about this some more next week.

(If pigs fly.)



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