I'm not the only one who could post...

I'm just the one who gives in first and does it.

So, how cool is chapter 6? I admired the slippery way in which the authors went from the philosophically intense issue of how and whether we should respond to all mass and energy by saying, "Ooh! That could run my X Box 360!" to the fascinating world of white dwarfs and black holes.

Not new to me, all that stuff about stars, but I confess that I have always previously skipped the math. Inspired by Darin's habit of doing the sums when he sees them in the book, I actually read the calculations, so I learned new things.

What did the rest of you like about Chapter 6? and do you want to have a bit of civilized debate about whether harnessing as much power as possible is necessary or wise?

There's a wonderful book about the Manhattan project called Brighter Than a Thousand Suns which says that it was that project that ended the option, for scientists, of saying "We're just learning stuff. We're innocent of what gets done with what we discover." The split between science (beautiful, pure, and clean) and technology (worldly, greedy, profit-centered) is gone, now.

What do you think?

So... Chapter 5

Here's my synopsis of Chapter 5. I'm still hoping that someone will help me out:

1. Everything travels through spacetime at speed c, which is to say at the speed of light. However, light travels only in space, not in time. Everything else does some of its traveling in time. Therefore, we don't get from place to place as fast as light does. In fact, we move so slowly (that is, we use so much of our share of c on traveling in time) that our experience of spacetime is quite different from light's experience -- or what light's experience would be if it were sentient.

2. We can think of distances between two points in space (Fayetteville and Shreveport) or two points in time (5:00 and 6:00). We can also think about two points in spacetime (waking up in bed and breakfast at the kitchen table). If the distance needs to have a direction, then we can think of it as an arrow, or a vector (studiously ignoring mosquitoes as disease vectors). Depending on what's important, we can describe distances in spacetime by as many as three numbers: length, height, width, and passage of time.

3. The spacetime distance between two points is always the same, mathematically speaking; it can be distributed differently, though. So if we consider the spacetime between my great-grandfather at Ellis Island and me, there's the distance in miles between us of 1314.68 or so; then he was at sea level so I'm higher; I don't know how width could be measured; and then there's the time difference of a century. Presumably, there could have been a great burst of light at Ellis Island at just that moment that the ship arrived from Antwerp and the spacetime between that and me now would be identical to the spacetime between Robert Allen Haden and me -- but it would be taken up entirely by space and not by time.

I have no idea what #3 would mean. "So much," as the authors say, "for vectors."

4. Billiard balls colliding will take off with the same amount of energy with which they collided, but in opposite directions -- except for friction, which spoils this story, so we leave it out. All the energy used in any undertaking is conserved: it doesn't get used up or anything. It's still there, just as the water we're now drinking is the same water the dinosaurs drank. Energy can be stored and used and moved around, but it doesn't diminish.

5. This hooks up with the idea of all the movement through spacetime adding up to c. But it's better because it makes a nicer equation with y.


What am I missing?

Having Trouble with Chapter 5

Knowing that some of the crowd were skiing in Colorado... in Ohio where apparently they have no computers... lazing around eating the remaining Christmas cookies.... I didn't want to forge ahead for fear of leaving anyone behind.

Now that Janet has brought up her concerns about global warming in Chapter 6, though, I feel justified in asking for help with Chapter 5.

I began to feel a little lost right at the point where the observer in the bed has the spacetime distance vector pointing up his time axis. It sounds uncomfortable, and figure 9 isn't helping.

I may be having trouble with vectors. I keep thinking about mosquitoes being vectors for malaria, and then there's the giant arrow to Manchester (I'm thinking of it in electric blue plastic)... Then they bring in hyperbolae and I'm lost.

Why can't we have momentum in time? It seems to me that momentum unavoidably exists in time as well as space. Why do these guys imagine that things are interesting or boring based on stuff like length? Have they actually begun rambling madly, or am I just missing the point?

Your assistance will be greatly appreciated.