You probably won’t read this, but I find it useful to document my thoughts were I can find them in the future.

I think that macroscopically, our future does look like our past.

When we stare off into the cosmos (into the past) at the extreme edges of our “hubble bubble” we see fewer objects that have large angular distances between them.

If instead, when I stared off into the cosmos, I was staring into the future, I would see fewer objects that have large angular distances between them.

If I lived in the universe where time was a small curled dimension, in that universe, the real past or future would be only a short “distance” from where I am at. The evolution of the universe would then depend on which direction I went around the circle (determining whether I was matter or antimatter) as well as how many times I went around the dimension (a parameter).

My perception of space would appear to be a superposition of states, ordered based on the relative number of times “distant” regions have traveled around the dimension.

If I imagine these states being side by side forming a tube, where time is motion around the tube, and space is down the length. Then either way I looked, I would see a superposition of continuously lower entropy states.

Time in this universe would be symmetric, since locally, time could be running backwards (and would look like a patch of antimatter), but that fact would not upset the global view from wherever I was.

When it comes to the whole universe, we don’t know enough to make definative statements, and in fact time itself is something rather strange. In some way the universe emerged with a local definition of time from a vacuum state or configuration (false vacua etc) we don’t fully understand, by mechanisms (Higgs, inflatons, landscapes) we only have a cursory understanding of. In fact we are waiting for the LHC to give us our first data set on that second part.

Lawrence B. Crowell

Interesting presentation, sparked a blog entry for me: http://ysfk.blogspot.com/2008/09/beginning-of-universe.html

I always thought it would be more elegant for our Creator to create things by defining the process and setting the right preconditions to make sure they happen.

Time/Entropy = the Process

Regards,
Yusuf

Did any time-travellers attend?

The idea of “space-time” led, in General Relativity, to the idea of space as being like a “rubber sheet” than could be curved as the basis of gravity. So people asked, what does “space” curve through unless there’s more space (hyperspace) around it. That led to many diagrams showing a surface in emptiness, and the notion we can generalize to a three-surface curved into a four-space (sic) etc.

But here’s a fundamental problem I and surely others have with thinking of “space” (in effect, the constraint domain of the movement of matter and radiation, right?) as being like a “sheet” (rubber or otherwise) that can be inside another “space” with more dimensions. Here I mean a macro space with more dimensions to “hold” a space with fewer, and not confusing with time either (so: a four-space dimensional manifold to “hold” a curved 3-D space within it.) Sure, in math I can just specify a manifold, a surface or space as part of another space by stating the rule for the locus of points. I can say, “the locus of points equidistant from a given point” which creates by semantic fiat a spherical shell in any space. The shell is literally curved (showing intrinsic non-Euclidean geometry), and has dimensionality one less than the parent space.

Some physicists and philosophers of science say, there really isn’t (or “doesn’t need to be,” seen as the same point to the empirical minded) some hyperspace that our space has to be “curved into”, it’s just a way of talking about what happens here. Hence you can imagine that space doesn’t really pucker around a mass, but rather that rulers shrink in the radial direction. Some writers literally phrase it that way. That effect would effectively seem to be space curvature (e.g., more rulers can be placed = more distance to travel, when going through the pucker versus around it, etc.) But even if curvature can be “simulated” by distorted rulers “on a flat space,”: don’t you need “real curvature” and not just the equivalent distortion on a flat surface, in order to get closed, finite volumes of space? (Otherwise, the mapping doesn’t work out does it?)

So as far as physics goes, in what sense is the “space” that holds how matter can move distinguished from the equally empty “space” that holds the first space? I know, there are quantum issues and maybe gravitons work differently, but we still can’t merely draw pictures of surfaces inside another “space” and think we’ve explained anything. Like I said, with mathematics you get to specify loci literally by saying so, but in a natural world there’s “something” that has to keep objects held inside a locus of points defined within a more bountiful (in whatever sense) “space”.

IOW, if there’s no difference in “kind” about space and its containing “hyperspace” then it’s just like trying to have water surfaces distinguished inside of water etc. – what makes the difference between them (unless you follow Tegmark’s modal realism.) So, what does that job? What keeps particles etc. penned in when there’s “more room” available in principle? (Please, no circular arguments or semantic tricks. And it isn’t just “metaphysics” to ask this, if a theory employs “spaces” as a physical constituent in any manner.)

Last question

Does the transformation from a right moving arrow to a left moving arrow imply that there is an additional rotational degree of freedom?

I think there has to be, even if it is heavily suppressed, and even if there are no intermediate orientations for the arrow.

I’ve been lurking at your site for a few months now. Nice blog!

even though the impetus of the collapse of each block building contains a considerable lateral component of force, each colored building pretty much falls down into its own footprint.

To me they don’t. I would bet that the line of maximum density of the debris is shifted forward form the center of the footprint, close to the “next” building.