Nothingness

[robertb]

What I find most difficult to understand about the B-Theory/model/spatial metaphor that it would seem that each point in time is thought of as 'containing' the the entirety of space matter and energy. Representing time spatially seems to degrade our ability meaningfully represent space spatially. Conceiving of the universe as infinite minimizes this difficulty conceptually but it feels like a cheap fix, sort of like a god of the gaps.

It is not really defined spatially though, it is defined in 4 dimensions, if that makes sense. It is, of course, trivially true that each "slice" of the spacetime block contains the entirety of space, matter and energy, or so it seems to me.

As far as infinite goes, who knows.

[Carrikature]

Because of entropy. Lower entropy is before and higher entropy is after, a physical reality. Don't conflate co-existent with co-location.

I am not conflating co-location with co-existent. There are points in space-time with relatively high entropy. There are other points with relatively low entropy. We perceive time as moving from points with low entropy to points with high entropy, but we could just as easily observe the opposite. There's zero explanation for why we only perceive low to high and never the reverse. 'Before' only refers to how we experience things, not to an actual description of the universe under B-theory.

[robertb]

I am not conflating co-location with co-existent. There are points in space-time with relatively high entropy. There are other points with relatively low entropy. We perceive time as moving from points with low entropy to points with high entropy, but we could just as easily observe the opposite. There's zero explanation for why we only perceive low to high and never the reverse. 'Before' only refers to how we experience things, not to an actual description of the universe under B-theory.

You perceive before to after because your brain is subject to the same entropy the rest of the universe is subject to.

[robrecht]

It is not really defined spatially though, it is defined in 4 dimensions, if that makes sense. It is, of course, trivially true that each "slice" of the spacetime block contains the entirety of space, matter and energy, or so it seems to me.

As far as infinite goes, who knows.

Isn't it still spatial, four-dimemenional space rather than three-dimensional space?

[robertb]

Isn't it still spatial, four-dimemenional space rather than three-dimensional space?

Not really, it is 4 dimensional spacetime.

[JimL]

I do not understand "time doesn't pass"... "conjoined together in time"

The point of that was that in B-theory, locations in time differ, but each location in time is just as real as any other. Without an actual flow to time, as in A-theory, terms such as "Now, and Then, take on different connotations and so they must be understood in that way. In B-theory "Now" is subjective, and so with respect to you at this moment, "now" only applies to your present location in time, but from an objective perspective, "Now" applies to all locations in time. So when I refer to the past as something happening right "Now," what I mean is that in B-theory, from an objective perspective, "now" and "then" are terms that can be applied to any point in time.

You should really be using spacetime and coordinates within spacetime. Keeps the semantics clear. But I think I get what you are saying.

Thats the physics explanation of it, but the physics explanation doesn't explain the experience or the illusion of times passing so one is only going to grasp the idea if they understand it from the perspective of being outside of time itself.

[Carrikature]

You perceive before to after because your brain is subject to the same entropy the rest of the universe is subject to.

This doesn't exclude the possibility of us perceiving entropy moving from high to low, though.

[Carrikature]

Isn't it still spatial, four-dimemenional space rather than three-dimensional space?

The fourth dimension would be time. The other three dimensions are space. That's why I used the (x,y,z,t) coordinate set in a previous post.

[robertb]

This doesn't exclude the possibility of us perceiving entropy moving from high to low, though.

The universe itself excludes that possibility, perhaps due to the Big Bang, or so it seems to have so far.

[Carrikature]

The universe itself excludes that possibility, perhaps due to the Big Bang, or so it seems to have so far.

You're going to have to support this claim.

[robertb]

The point of that was that in B-theory, locations in time differ, but each location in time is just as real as any other. Without an actual flow to time, as in A-theory, terms such as "Now, and Then, take on different connotations and so they must be understood in that way. In B-theory "Now" is subjective, and so with respect to you at this moment, "now" only applies to your present location in time, but from an objective perspective, "Now" applies to all locations in time. So when I refer to the past as something happening right "Now," what I mean is that in B-theory, from an objective perspective, "now" and "then" are terms that can be applied to any point in time.

There is no now. Your now is actually your past. Keep that in mind and these objections go away.

Thats the physics explanation of it, but the physics explanation doesn't explain the experience or the illusion of times passing so one is only going to grasp the idea if they understand it from the perspective of being outside of time itself.

It is counter-intuitive, I suppose. However, our best physics kinda demands it.

[robertb]

You're going to have to support this claim.

Have you ever experienced time moving backwards, or know of any evidence of such an occurrence?

If it was possible to travel FTL, you might just see such an occurrence, but that doesn't seem to be a physical possibility.

[Carrikature]

Have you ever experienced time moving backwards, or know of any evidence of such an occurrence?

If it was possible to travel FTL, you might just see such an occurrence, but that doesn't seem to be a physical possibility.

This is exactly my objection to B-theory. There is no explanation within B-theory for this. The fact that no one has ever observed otherwise is a point in favor of A-theory, not B-theory.

[JimL]

This doesn't exclude the possibility of us perceiving entropy moving from high to low, though.

This is what I meant above when I said that the physics explanation of B-theory doesn't explain experience. If all locations in time are co-existent why is the experience of time one directional? The state of the entropy in locations of time doesn't speak to actual experience.

[robertb]

This is exactly my objection to B-theory. There is no explanation within B-theory for this. The fact that no one has ever observed otherwise is a point in favor of A-theory, not B-theory.

You lost me. No explanation for what? The fact that no ne has ever observed otherwise is due to entropy. Remember, you are part of the universe as well.