Reductionism

[ryan]

What could the nature of 'now' even be in relation to Eternalism?

It can be thought of as something like a "spotlight" projecting information as it moves through the universe's eternal structure. It is the "mental now" even though everything physical is already there. See http://web.mit.edu/bskow/www/research/timeinrelativity.pdf .

Possibly. Yet measurement of time/rates of change appears to be related to entropy, physical processes.....

Do mean that it would be too much of a coincidence for there to be a spotlight and an intrinsic change in the universe as the spotlight travels through it; or ...?

I am more in the growing block universe camp even thought there are many problems with it too.

 

[Bomb#20]

A growing block universe assumes the existence of a universal now.

Relativity says that there's no such thing.

How does a growing block universe assume the existence of a universal now? It's basically a crystal growth model -- new spacetime gets added to the surface of the block of existing spacetime. So a "universal now" would presumably be a (hyper)plane that has block of spacetime on one side, and does not yet have any spacetime on the other side, that can serve as a preferred reference frame. Which is to say, it's a face of the crystal. So why would a flat face have to exist anywhere on the growing block? Who says the crystal has to grow uniformly?

How can that hyperplane have a shape that allows for events to have different sequence for different observers?

What hyperplane? That's my point: there is no hyperplane -- no "universal now" -- provided the growing block universe grows in a bumpy irregular fashion, with some locations expanding along the time dimension ahead of others. Any individual observer will perceive the time of distant events based on her own relativistic reference frame, and will construct a hyperplane in her imagination that's the set of all events that are simultaneous from her point of view. But none of those imagined hyperplanes will correspond to the actual shape of the growing block. A typical observer's mental hyperplane will slice through the block in some places where the block has already grown beyond it, and pass beyond the existing universe in other places where the growth hasn't yet caught up with that observer's imagination. (And no worries -- the growth can catch up in time. All not-yet-caught-up locations are outside the observer's light-cone, so everything she can actually see will be comfortably within existing spacetime, provided the bumps on the surface are never steeper than 45 degrees.) Consequently, none of the observers are privileged. So this model doesn't contain the "absolute rest" reference frame that relativity says doesn't exist.

As far as preferring one relativity-consistent model to another goes, the growing block model beats the eternal block model hands down, IMHO. The eternal block model has a nasty entropy problem. If the whole thing just "is", without ever "becoming", then what accounts for the state of the universe in 2018 being consistent with having evolved from a much-lower entropy state of the universe in 1918? If you take, as the "2018 state of the universe", an arbitrary slice through an arbitrary eternal block, and then you play the laws of physics backwards from that slice a hundred years, the state you compute for 1918 will with 99.9999+% probability have a greater or equal entropy than the 2018 state. Only a few very special arrangements of matter in 2018 are compatible with having resulted from running the laws of physics forward from a lower entropy 1918 state.

Here's a simplified example. Let's say you take as the state of the universe the following: a star, a gas giant, and a line of 19 dirty snowballs about to crash into the gas giant. Pick their exact positions and velocities any way you please. Now run the law of gravity backward for two years. You are not going to retrodict that all those snowballs coalesce into a single comet, unless you are ridiculously lucky in your selection of positions and velocities. The trouble with the eternal block model of time is that improbabilities on that scale happen constantly, every single time you look, for no comprehensible reason. The state of the universe just is always consistent with having evolved from a low-entropy predecessor state. Why? No reason, it just is. By magic, apparently.

In the growing block model, there's a perfectly straightforward comprehensible explanation for this otherwise insane coincidence: the 2018 state is exactly consistent with the 1918 state precisely because it was actually computed from it. That's what growth of the block is: it's the laws of physics incrementally computing the future, from the past, epsilon of spacetime by epsilon of spacetime.

 

[DBT]

Possibly. Yet measurement of time/rates of change appears to be related to entropy, physical processes.....

Do mean that it would be too much of a coincidence for there to be a spotlight and an intrinsic change in the universe as the spotlight travels through it; or ...?

I am more in the growing block universe camp even thought there are many problems with it too.

Yes, the apparent intrinsic change seems to be a barrier. But it may be an illusion of consciousness. Consciousness perceiving links and interpreting these as change, change as a flow of events which we call time.

 

[Speakpigeon]

How can that hyperplane have a shape that allows for events to have different sequence for different observers?

What hyperplane? That's my point: there is no hyperplane -- no "universal now" -- provided the growing block universe grows in a bumpy irregular fashion, with some locations expanding along the time dimension ahead of others. Any individual observer will perceive the time of distant events based on her own relativistic reference frame, and will construct a hyperplane in her imagination that's the set of all events that are simultaneous from her point of view. But none of those imagined hyperplanes will correspond to the actual shape of the growing block. A typical observer's mental hyperplane will slice through the block in some places where the block has already grown beyond it, and pass beyond the existing universe in other places where the growth hasn't yet caught up with that observer's imagination. (And no worries -- the growth can catch up in time. All not-yet-caught-up locations are outside the observer's light-cone, so everything she can actually see will be comfortably within existing spacetime, provided the bumps on the surface are never steeper than 45 degrees.) Consequently, none of the observers are privileged. So this model doesn't contain the "absolute rest" reference frame that relativity says doesn't exist.

Ah, thanks! This seems ridiculously like very exactly the thing I was asking anybody to please explain why it wouldn't be a problem. So, I take it there was indeed a problem and no explanation will be forthcoming. I'm reassured about my sanity and at my age it's... reassuring.

You're a bit wordy but still, good point!

As far as preferring one relativity-consistent model to another goes, the growing block model beats the eternal block model hands down, IMHO. The eternal block model has a nasty entropy problem. If the whole thing just "is", without ever "becoming", then what accounts for the state of the universe in 2018 being consistent with having evolved from a much-lower entropy state of the universe in 1918? If you take, as the "2018 state of the universe", an arbitrary slice through an arbitrary eternal block, and then you play the laws of physics backwards from that slice a hundred years, the state you compute for 1918 will with 99.9999+% probability have a greater or equal entropy than the 2018 state. Only a few very special arrangements of matter in 2018 are compatible with having resulted from running the laws of physics forward from a lower entropy 1918 state.

Here's a simplified example. Let's say you take as the state of the universe the following: a star, a gas giant, and a line of 19 dirty snowballs about to crash into the gas giant. Pick their exact positions and velocities any way you please. Now run the law of gravity backward for two years. You are not going to retrodict that all those snowballs coalesce into a single comet, unless you are ridiculously lucky in your selection of positions and velocities. The trouble with the eternal block model of time is that improbabilities on that scale happen constantly, every single time you look, for no comprehensible reason. The state of the universe just is always consistent with having evolved from a low-entropy predecessor state. Why? No reason, it just is. By magic, apparently.

In the growing block model, there's a perfectly straightforward comprehensible explanation for this otherwise insane coincidence: the 2018 state is exactly consistent with the 1918 state precisely because it was actually computed from it. That's what growth of the block is: it's the laws of physics incrementally computing the future, from the past, epsilon of spacetime by epsilon of spacetime.

Ah, yes, that's another thing. I never actually thought about that in those terms but entropy is a good way to put it.

Me, I only thought about this in terms of the irrelevance of causality. Why would there be any causal relation between past and future if all there was would be the so-call "eternal block universe". OK, you could say it's just the way it is but then we could offer any absurd model and say the same thing, it's the way it is.

So, still a bit wordy but excellent post altogether.

And I'll be waiting anxiously for anybody else to offer a clarifying "explanation" to illuminate our understanding of reality to us all!

Thanks,
EB

EDIT: I think fromderinside's broken clock model works better than the "eternal block" model.

 

[ryan]

Possibly. Yet measurement of time/rates of change appears to be related to entropy, physical processes.....

Do mean that it would be too much of a coincidence for there to be a spotlight and an intrinsic change in the universe as the spotlight travels through it; or ...?

I am more in the growing block universe camp even thought there are many problems with it too.

Yes, the apparent intrinsic change seems to be a barrier. But it may be an illusion of consciousness. Consciousness perceiving links and interpreting these as change, change as a flow of events which we call time.

This kind of exposes the consciousness a little, don't ya think?

 

[DBT]

Yes, the apparent intrinsic change seems to be a barrier. But it may be an illusion of consciousness. Consciousness perceiving links and interpreting these as change, change as a flow of events which we call time.

This kind of exposes the consciousness a little, don't ya think?

I'm not sure what you mean. I can interpret your remark in several ways.

 

[Bomb#20]

Ah, yes, that's another thing. I never actually thought about that in those terms but entropy is a good way to put it.

Me, I only thought about this in terms of the irrelevance of causality. Why would there be any causal relation between past and future if all there was would be the so-call "eternal block universe". OK, you could say it's just the way it is but then we could offer any absurd model and say the same thing, it's the way it is.

So, still a bit wordy but excellent post altogether.

Thanks; and I agree I was being wordy; and your comment about causality effectively makes the same point more concisely. Ultimately entropy is how we tell which of two correlated events is the cause and which is the effect. But my argument was aimed at bilby. I wanted to preempt his expected comeback about some people needing comfort due to being unable to abandon their preferred concept of causality. It's one thing for him to belittle those he's arguing with, and quite another to belittle the 2nd Law of Thermodynamics.

 

[ruby sparks]

Yes, the apparent intrinsic change seems to be a barrier. But it may be an illusion of consciousness. Consciousness perceiving links and interpreting these as change, change as a flow of events which we call time.

This kind of exposes the consciousness a little, don't ya think?

I'm not sure what you mean. I can interpret your remark in several ways.

If I were to guess, I might wonder if he's gleefully pointing out, Descartes-style, that consciousness seems to (or does) reliably, exist.

I think he's on a mission to ferret out mind-deniers.

He would probably like to find one because if he does he's got killer points to put to them, like 'there is such a thing as conscious experience'.

 

[Angra Mainyu]

In a block universe (eternalism) nothing emerges. Everything is eternal without change. However, this seems to go against our perception of reality.

But with a growing block universe, things become. The present emerges. This maybe just for the consciousness, or it might be that a new identity of the whole universe constantly emerges. Either way, new perceptions emerge, or the present emerges - something emerges!

Something seems to be emerging while much stays conserved.

A growing block universe assumes the existence of a universal now.

Relativity says that there's no such thing.

How does a growing block universe assume the existence of a universal now? It's basically a crystal growth model -- new spacetime gets added to the surface of the block of existing spacetime. So a "universal now" would presumably be a (hyper)plane that has block of spacetime on one side, and does not yet have any spacetime on the other side, that can serve as a preferred reference frame. Which is to say, it's a face of the crystal. So why would a flat face have to exist anywhere on the growing block? Who says the crystal has to grow uniformly?

That sounds good as near as I can tell (though I admit, on this it's quite near actually ), but I'm not sure it keeps the main characteristics of the growing block in philosophy - namely, that the A theory holds, and that the past and the present are real, but the future is not - unless perhaps one relativizes also existence, but that too might cause trouble for those metaphysical theories. But I don't know enough about the matter to be sure, so I'd like to ask whether I'm getting this right, or there is another way of keeping the A series? (or you just aren't concerned with the A series at all, and your theory is not related to metaphysical growing block theories defended by A theorists?).

 

[Speakpigeon]

But I don't know enough about the matter to be sure, so I'd like to ask whether I'm getting this right, or there is another way of keeping the A series? (or you just aren't concerned with the A series at all, and your theory is not related to metaphysical growing block theories defended by A theorists?).

Me, I don't see what would necessarily be wrong with a theory of time that would indulge our sense of time. The B-theory doesn't even do that. The B-theory isn't a theory of time. It's a theory that claims there's no time because all there is is space. And then, to explain the weird occupation of space by stuff in that N-dimensional space, you have to acclimatise all physical laws that mention time so as to get rid of time... by replacing the time dimension with some weird space dimension. In effect, you're substituting to the time dimension a space dimension that's behaving like a time dimension! Nice! So now you have space dimensions that are really space dimensions and another space dimension that just happens to be entirely entirely different. What's the point of all that already?!

The A-theory of time is probably a bit naive as everything we think about the real world. So, yes, it may need some adjustment when science discovers something new but in any case, any theory of time has first to be compatible with our sense of time.

And, oops, sorry to have hijacked your post!
EB

 

[Speakpigeon]

I'm not sure what you mean. I can interpret your remark in several ways.

If I were to guess, I might wonder if he's gleefully pointing out, Descartes-style, that consciousness seems to (or does) reliably, exist.

I think he's on a mission to ferret out mind-deniers.

He would probably like to find one because if he does he's got killer points to put to them, like 'there is such a thing as conscious experience'.

Nah, ryan's quip was just too subtle for DBT's brain.

Stuff happens.
EB

 

[Speakpigeon]

Ah, yes, that's another thing. I never actually thought about that in those terms but entropy is a good way to put it.

Me, I only thought about this in terms of the irrelevance of causality. Why would there be any causal relation between past and future if all there was would be the so-call "eternal block universe". OK, you could say it's just the way it is but then we could offer any absurd model and say the same thing, it's the way it is.

So, still a bit wordy but excellent post altogether.

Thanks; and I agree I was being wordy; and your comment about causality effectively makes the same point more concisely. Ultimately entropy is how we tell which of two correlated events is the cause and which is the effect. But my argument was aimed at bilby. I wanted to preempt his expected comeback about some people needing comfort due to being unable to abandon their preferred concept of causality. It's one thing for him to belittle those he's arguing with, and quite another to belittle the 2nd Law of Thermodynamics.

Yes, let's just see how many days will pass before you get a cogent answer.
EB

 

[ryan]

Yes, the apparent intrinsic change seems to be a barrier. But it may be an illusion of consciousness. Consciousness perceiving links and interpreting these as change, change as a flow of events which we call time.

This kind of exposes the consciousness a little, don't ya think?

I'm not sure what you mean. I can interpret your remark in several ways.

In other words, the present in an eternal universe is something moving through the universe, like a ghost, like a consciousness.

 

[steve_bank]

A little calculus can help to picture a definition of the now or present.

Consider an arbitrary curve. Imagin the curves represents velocity vs time. Y is velocity, x is time.

Pick an interval on the x axis and call it (x1 - x2). Call th interval dx for change in x.

As dx approaches zero the time variable approaches an instantaneous value. As dx can not actually go to zero we say as dx approaches o time approaches the instantaneous value on the curve.

Time can never be exactly the present, now only exists as a moving interval in time. In human experience the present can mean an interval of a week or a minute or a second.

 

[ryan]

A little calculus can help to picture a definition of the now or present.

Consider an arbitrary curve. Imagin the curves represents velocity vs time. Y is velocity, x is time.

Pick an interval on the x axis and call it (x1 - x2). Call th interval dx for change in x.

As dx approaches zero the time variable approaches an instantaneous value. As dx can not actually go to zero we say as dx approaches o time approaches the instantaneous value on the curve.

Time can never be exactly the present, now only exists as a moving interval in time. In human experience the present can mean an interval of a week or a minute or a second.

Our limitations to measure only intervals of time shouldn't mean that now, as in a point in time, cannot exist. If time were continuous, we would still only find intervals of time. Applying math/calculus in this way does not tell us anything about the structure of time.

 

[DBT]

I'm not sure what you mean. I can interpret your remark in several ways.

If I were to guess, I might wonder if he's gleefully pointing out, Descartes-style, that consciousness seems to (or does) reliably, exist.

I think he's on a mission to ferret out mind-deniers.

He would probably like to find one because if he does he's got killer points to put to them, like 'there is such a thing as conscious experience'.

Nah, ryan's quip was just too subtle for DBT's brain.

Stuff happens.
EB

Ha, Ha, Noddy throws his two bobs worth into the ring....while attempting to demonstrate just how clever he himself happens to be....

 

[DBT]

I'm not sure what you mean. I can interpret your remark in several ways.

In other words, the present in an eternal universe is something moving through the universe, like a ghost, like a consciousness.

Except that mind is something the universe is doing in the form of an active brain....it being the brain that interprets the complex relationships of the universe at large as being the 'flow of time'

 

[steve_bank]

A little calculus can help to picture a definition of the now or present.

Consider an arbitrary curve. Imagin the curves represents velocity vs time. Y is velocity, x is time.

Pick an interval on the x axis and call it (x1 - x2). Call th interval dx for change in x.

As dx approaches zero the time variable approaches an instantaneous value. As dx can not actually go to zero we say as dx approaches o time approaches the instantaneous value on the curve.

Time can never be exactly the present, now only exists as a moving interval in time. In human experience the present can mean an interval of a week or a minute or a second.

Our limitations to measure only intervals of time shouldn't mean that now, as in a point in time, cannot exist. If time were continuous, we would still only find intervals of time. Applying math/calculus in this way does not tell us anything about the structure of time.

Ryan, it is a metaphor mot literal. Like something being a sticky wicket for the Brits from Cricket or something being a slam dunk in the USA from basketball. Metaphors are how we use visual images to communicate subjective ideas.

 

[ryan]

I'm not sure what you mean. I can interpret your remark in several ways.

In other words, the present in an eternal universe is something moving through the universe, like a ghost, like a consciousness.

Except that mind is something the universe is doing in the form of an active brain....it being the brain that interprets the complex relationships of the universe at large as being the 'flow of time'

There is no "doing" or "activity" in an eternal universe. There is just observation of different parts of a 4d universe.

 

[DBT]

Except that mind is something the universe is doing in the form of an active brain....it being the brain that interprets the complex relationships of the universe at large as being the 'flow of time'

There is no "doing" or "activity" in an eternal universe. There is just observation of different parts of a 4d universe.

If so, how do you account for your remark? - ''In other words, the present in an eternal universe is something moving through the universe, like a ghost, like a consciousness.'' - Ryan.

Observation, apparently, is an activity?