Hello and good morning.  It’s Thursday, in case you didn’t already know.  Though, if you’re reading this on some day other than Thursday, then I guess it’s not Thursday for you.

You could think of it as us being on sort of parallel time streams—and indeed, we each carry our own “proper time” around with us, according to Relativity.  And while communication is possible between those timelines, it is communication in one direction only.  I can send messages to you, where and when you are now reading this, but you cannot send messages back to me.

Wait, wait, I hear you say*, you can communicate back to me in my parallel time, because you can comment on the post below (there’s only one person who does this with any regularity, but sure, it’s possible for you to comment, in principle).  So it’s not one-directional communication.

Ah, but that’s where I’m being esoterically precise here.  You cannot communicate back to me where and when I am now.  You can only communicate with some “future” point, something quite a bit down the line from where and when I am as I write this.  And I cannot then communicate with the you that is writing back to me, but only to some future state of you.

Okay, well, duh, you say**, that’s just how time works.

That only seems unremarkable to you because it’s all you’ve ever known, and you’re adapted to it—personally and evolutionarily.  But if you step back, so to speak, it can seem quite remarkable.

Special Relativity demonstrates that space and time are not separate but are intertwined, and space and time bleed into one another depending upon relative motion—indeed, within the event horizon of a black hole, it appears that space and time are flipped ninety degrees (as though along an axis at 45 degrees to those of space and time) so to speak, so that space becomes time, which is part of why you can never get out of the black hole—you cannot reverse time, but must move forward to its end at the singularity, if such a thing exists, which is probably not the case.

So, why does time work differently than space?  After all, If I live on a street parallel to yours, I can cross to your street by any of a number of cross-streets, cut through back yards, follow alleyways, etc., in more or less any direction, and I can return in a similar fashion.

Imagine, though, if it worked the following way.  I start at my address—let’s imagine it’s number 13*** for the moment—and want to go to your street.  But I can only go by routes that are at higher address numbers than my address.  And then, when I want to return to my street I have to go down (or would that be up?) the numbers on your street, to take a cross-street (or whatever) that’s even farther from my house.

So, say I crossed to your street right after number 17, where a cross-street exists.  And say the numbers on your street line up with those on my street, just for simplicity’s sake****.  Luckily, your house is at number 19 on your street, so I can reach it.  I could never go back to number 17 on your street, let alone number 13.

But when I want to leave your place, I can only head toward higher numbers, so I can’t go back to the cross street near 17.  I have to go down to, say, the street past number 23.  But even once I get to my street, I can’t go back to my house!  I must head in the direction of higher numbers.

I can only get back to my house if my street goes all the way around the world and comes back to my house from the other direction, and I suspect that it doesn’t do that.  I’m stuck farther down my own street, homeless now, because I cannot reach my address.  And it’s not as though you can take me in, because I cannot go back to your address, either, and if you leave your house to meet me, you will be in the same predicament in which I languish.

That’s sort of how time seems to work.  Unlike the three spatial dimensions, we cannot simply choose our direction, change our mind and our course, go back to where we came from or even just go around and around the block (which may or may not be a stupid thing to do—see yesterday’s post).  Why is time different?  The laws of physics appear to be locally time symmetric as they are space symmetric.  In other words, they work the same backwards and forwards.  But macroscopically, time is directional.

I’ve speculated a bit on this over at Iterations of Zero.  I’ll try to link to the pertinent blog post(s).  Some of that speculation compares the directionality of time that we all experience to the directionality of space that exists here on the surface of the Earth.

Wait, you say, what do you mean “the directionality of space”?  (You do love to interrupt, it seems.)  Well, think about it.  When you’re on the Earth, the directions forward/backward and left/right (or any other non-parallel axes you might choose along the surface, such as north/south and east/west) are freely navigable.  You can go in any direction or combination of directions along them, barring local obstacles.  But the same cannot be said for up/down.  It’s much harder to go up than to go left or forward.  And if you lose support beneath your feet, you will be unable to avoid going down.

Perhaps, as has been speculated by others with greater expertise than mine, the “Big Bang” provides or entails a local state that creates a local directionality to time, but far enough away from that “event”, time will become just as non-directional as any spatial dimension.

This is the way it works with the dimensions of 3D space:  when you’re far enough away from a local “event”, such as the surface of the Earth, the dimensions are all freely navigable.  But there’s not too much to do there, and it seems that life and complexity are likely to emerge only where these local gradients—whether in space or in time or both—exist, doing their part to provide the “free energy” which is required by things like life.

Anyway, that’s my random set of thoughts for this Thursday.  I hope you have a good day.  As for me, I continue to follow the local directionality of my metaphorical space; in other words, I continue to trend downward.  I do not perceive any other available direction for me.

TTFN

*Or I think I do.  I have terrible hearing and persistent tinnitus, so I might have been hearing the sound of rain on the roof or of wind in the trees or of otherworldly, eldritch creatures scratching at the fabric of reality, trying to break through the barriers between their realms and ours.  Probably not, though.

**You’re a bit rude, don’t you think?

***It’s not, unfortunately.

****Simplicity is one high-maintenance person.