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 Post subject: Re: The Speed of Causality
PostPosted: Thu Apr 20, 2017 12:10 pm 
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I watched the entire video this morning, before I posted. I confess I still don't see the problem. Causality propagates at the speed of light. Even with a Humean understanding of causality, so what? Either agents aren't really agents, which I'm absolutely positive is not what you're arguing, or the causality of the agent at some point reaches its recipient, and that's when the actualization of the recipient's potential happens. How is that a problem?

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 Post subject: Re: The Speed of Causality
PostPosted: Thu Apr 20, 2017 3:05 pm 
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We can do this in Humean terms if need be. Since physicists don't like action at a distance, we have fields to transmit forces, and particles are manifestations of the fields. I'm sure physicists won't like the way I put that, but it's close enough for now.

So cause A produces its effect on object B by actualizing the potential of the field to change in a certain (possibly indeterminate) way. That change propagates through the field at no more than the speed of light, actualizing potential of the field as it does so. When the change of field encounters object B, it actualizes its potential.

Think of gravity, which warps spacetime to produce its effects.

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 21, 2017 7:40 am 
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gherkin wrote:
Yes, right, I clearly needed to spend more time watching a video I'm not interested in before I tried to help you with your question. That was thoughtless of me. Your link sends me to a particular and brief moment in the video--a moment which I, naturally, understood to be the moment you expected your helpers to watch. If you had expected us to watch the whole thing, I'd have thought you'd have linked us to the beginning of it. But honestly, I wouldn't have watched the whole thing anyway.

Anyway, I hope you figure this causality stuff all out. Best of luck. :salut:

:roll: Hopefully you at least feel better about yourself now. Anyway, on to serious people.

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I watched the entire video this morning, before I posted. I confess I still don't see the problem. Causality propagates at the speed of light. Even with a Humean understanding of causality, so what? Either agents aren't really agents, which I'm absolutely positive is not what you're arguing, or the causality of the agent at some point reaches its recipient, and that's when the actualization of the recipient's potential happens. How is that a problem?

Obi-Wan Kenobi wrote:
We can do this in Humean terms if need be. Since physicists don't like action at a distance, we have fields to transmit forces, and particles are manifestations of the fields. I'm sure physicists won't like the way I put that, but it's close enough for now.

So cause A produces its effect on object B by actualizing the potential of the field to change in a certain (possibly indeterminate) way. That change propagates through the field at no more than the speed of light, actualizing potential of the field as it does so. When the change of field encounters object B, it actualizes its potential.

Think of gravity, which warps spacetime to produce its effects.

I don't really care if we can or can't do this in humean terms, except for the obvious fact that the humean notion is silly and ultimately self-contradictory for reasons we're both well aware of. What I care about is how this nuances (or helps us nuance) the A/T understanding of time.

The simple statement that "causality propagates at the speed of light" may have us on the right track. I don't know, so I'd like to explore it. My first thought when you say that is you're talking about intermediate causes. To go back to our glass being broken, as you get smaller and smaller, you realize--as in the case with all motion--that the whole is moved by the parts, such that the parts become mediate or instrumental causes. And that happens, you're saying, no faster than the speed of light; at the speed of light because where there is no mass there is no impedance to causality working most efficiently and where there is mass, it works at the maximum speed in can given the impedance. (So that last part, especially, is something I'm extrapolating from your statement. Curious if you think it's the right deduction all the same.)

If that's what you're saying, I think it's right as far as it goes. But it leaves hanging the question I'm trying to raise. The speed of light isn't arbitrary. It isn't that light is special, that the universe conspires to make sure nothing moves faster than light. The famous E=mc^2 is misleading when "c" is called "the speed of light" because it is only the speed of light accidentally. I mean that any massless particle must necessarily move at c, because c is speed at which causality itself operates in our physical universe without impedance. Since photons in a vacuum have no impedance, they move at this speed, and so we call it the speed of light. But now we're looking at this "speed of causality." While I think what you're saying is true as far as it goes, it takes as an assumption the thing I'm questioning: namely, what "speed of" means when talking about "causality" and how that relates to time. In particular, time itself is measured as the before and after change; speed is distance divided by time. So speed should be distance divided by the measure before and after a given [set of] change[s]. I'm sensing a real circularity here. Again, it's in the term "the speed of causality." "Speed of" is only meaningful when considering locomotion. Maybe you could use it some metaphorical sense . . . the "speed" at which a leaf changes color. But even that relies on locomotion, because the particles within the leaf that causes the color change are literally moving from here to there, and this at the speed of causality less any given impedance.

So, again, back to this idea of the speed of causality. "Speed" presupposes time, which presupposes causality. But you can't define causality by causality. And I think the recognition of this is implicit in Aquinas' fundamental definition of causality as the reduction of act to potency in which he has both things happening simultaneously. They happen together. On this view, there is no "speed of causality," because causality itself is instantaneous. Put differently, you can't measure the speed of the present, because the present just is what is. But speed, by its nature, presupposes temporality--it measures what was at t1 and what was (or is or will be) at t2. Put yet another way, speed or rate of change more generally is necessarily and definitionally a temporal concept, whereas causality is not. Causality necessarily gives rise to temporality but is not itself temporal (or, at least, the reduction of the potency to act, insofar as the two things are happening together, are not essentially temporal).

I could say more, but this has gone on way longer than I intended and long posts are hard to read. Is my question becoming clearer?

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 Post subject: Re: The Speed of Causality
PostPosted: Mon Apr 24, 2017 10:00 pm 
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Peetem reminded me that I'm still trying to get my head around this. Is the question dealing with change as instantaneous? Because from the evidence of the senses, obviously that's not the case, and St. Thomas and Aristotle wouldn't make a mistake of that sort. So I'm still not seeing the issue.

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 Post subject: Re: The Speed of Causality
PostPosted: Tue Apr 25, 2017 9:38 am 
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Without all the nuance, yes, it is about change being instanteous--at least at a fundamental level. The essential idea to the A/T explanation of causality, as I understand it, is that two things exist simultaneously, such that the change itself is present with the two things. The ball is shattering the window. The knife is cutting the orange. The potter's hand is shaping the clay. Grant the different types of causality (formal, efficient, material, final) and the different types of causal chains (per se and per accidens). I'm talking here very narrowly about efficient causality of either a per se or per accidens type.

The simplest I can state this, at least right now I think, is that the notion "speed of causality" strikes me as self-contradictory. For "speed of" necessarily presumes a temporality, which presumes causality. Causality can't have a "speed." You can have a collection of causes and measure how fast they happened. But the single causal event itself doesn't strike me as a temporal thing except in its relation to other temporal things (this change happened after that one and is happening before that one will). But it seems to me that any particular change just is present. No?

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 Post subject: Re: The Speed of Causality
PostPosted: Tue Apr 25, 2017 10:09 am 
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Then how does change happen over time? It clearly does. I think you're restating Zeno's paradox.

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 Post subject: Re: The Speed of Causality
PostPosted: Tue Apr 25, 2017 10:44 am 
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Could be, but right now I'm inclined to deny that, strictly, change doesn't happen over time for the simple reason that time is the consequence of change and not vice versa. When we say that change happens over time, it seems to me that we are talking about a collection of accumlated changes any particular thing accrues. And that seems highly consistent with, if not almost predictive of, some version of relativity. So as far as I tell, this reduction of potentiality is instantaneous. But then we measure the before/after, which results in something we conventionally call time. We then see a subsequent reduction of another potentiality, which is also instantaneous. But the very fact that this second change is subsequent to the former--that relation--is what gives us a continuous notion of time. So, again, time is derived from change, which is derived from causality. Causality itself doesn't have a time (except, again, insofar as this cause/effect relationship is temporally related to another cause/effect relationship).

It seems an obvious move at this point to just say the video, in speaking of "the speed of causality," is just talking about the closest possible temporal relation between two such changes. More technically, then, we wouldn't talk about the speed of causality but rather the closest possible temporal relation between two causally connected events. And maybe that's all the video is trying to say in too vague language. But I get the impression that he's trying to say something more, something about causality itself. For the sake of argument, can you see and if so agree or disagree that if he is trying to say that causality itself has a temporal boundary that such a statement would be problematic?

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 Post subject: Re: The Speed of Causality
PostPosted: Tue Apr 25, 2017 11:43 am 
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I have no quarrel with the first paragraph, nor with the first two sentences of the second. And I'm not sure what it would mean for causality to have a temporal boundary--as in, not that I question the implications of it, but that I'm not sure it's a meaningful combination of words.

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 Post subject: Re: The Speed of Causality
PostPosted: Tue Apr 25, 2017 12:40 pm 
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I think that is getting to my frustration, Obi. The phrase "temporal boundary of causality itself" is, I think, meaningless. Because, again, causality itself isn't a temporal thing. The things changing are temporal. The cause is temporal as is the effect (in the case of material objects, anyway). But causality itself isn't temporal. It is that by which we define temporality. So if all that is true, I think the very phrase, "the speed of causality" is highly problematic.

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 Post subject: Re: The Speed of Causality
PostPosted: Thu Apr 27, 2017 12:56 pm 
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I'm not sure this answers your question per se, Jac, (heck, I don't even pretend to understand the subject matter) but the below links seem to insinuate an answer, so far as I can tell.

How does traveling faster than light break causality

I took down some notes I deemed of relevance which I am quoting (and paraphrasing). You would probably have to watch the video (narrated by the same person as your link) to understand the references but here they are nonetheless.

Quote:
So the notions "before" and "after" are relative; but only between events that cannot influence each other, like the firing of the two engines. On the other hand, in every reference frame the flash of light occurs before the two spaceships fire their engines. There is a causal relationship between those events.

What's the difference? Two events can only be in a causal relationship if the (spatial) distance between them divided by the time difference between them is less than the speed of light. (In other words, one could be observed from the other.) If this is true in one reference frame, it will be true in every reference frame, even though different observers may see different distances (relativistic shortening) and times (time dilation). The math just works this way.

Conversely, if the spatial distance between two events divided by the time difference is larger than the speed of light, the events cannot be causally related, and they will appear in different temporal orders in different reference frames.

So this is very important: causally connected events always occur in the same order from any point of view. Cause always precedes effect.


The second link, The Geometry of Causality, at 8:00:
Quote:
Space-time interval comes directly from Lorenz Transformation, the only measurement of space-time separation that is unchanging, irrespective of any frame of reference.


And at about 9:30 referring to the space-time grid:
Quote:
... always slide down the steepest path, adjusting direction merely adjusts the grid so that I am always sliding down the steepest path (time going forward), i.e. can never slide upward (backwards in time). Uphill is impossible as long as the cosmic speed limit is maintained.


But (and there is always a but), in the third link, What Happens at the Event Horizon?, it all goes uphill from there (pardon the pun). The notion of causality is completely reversed in black holes and beyond (at the event horizon). The simulation of the Penrose Diagram is absolutely awesome, though. :mrgreen:

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 Post subject: Re: The Speed of Causality
PostPosted: Thu Apr 27, 2017 6:26 pm 
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Thanks for reminding me of those videos. I love the series. :)

I had a response prepared, but I think I need to think about it more. I'll say briefly that, in thinking about the notion that a photon (or any massless particle) not having a past light cone and so the relation of light to time (and so light to causality itself) . . . I came across the notion that a theoretical observer moving at the speed of light doesn't actually experience time. It might take a photon eight minutes to get from the sun to the earth. But from the photon's perspective, the movement is instantaneous. To the photon, no time has passed (because there has been no change (because no effects, because no past light cone)), but when it arrives, from it's perspective, time around it has been in fast forward such that "when" it left the sun I was eight minutes younger and when it reaches me I am eight minutes older "instantaneously." And that gets to the point of the videos you mentioned above. Were you to go faster than that, then "causality" would break because I would get younger and younger and younger the faster you went until eventually you would go "backward" in time -- the photon would literally reach me before it left the sun!

Anyway, that raises questions about the relation of light to space that I don't know how to answer. I can make some sense of the photon not experiencing time/change between its origin reaching its destination. But what about all the in between space? To make it visual, let the S below be the sun, the E be the earth, the P be the photon, and the number the time (from the perspective of some observer other than the photon):

S--P1-----------P2-----------P3-----------P4-----------P5-----------P6-----------P7-----------P8--E

So it takes roughly eight units of time for the photon to get from S to E. For P, that's instantaneous. For any observer, regardless of reference, that movement can be measured at a speed of about 186kmps. But how does that not imply that "where" the photon is at P1 and P8 are not the same place? Obviously they can't be, because the nature of time itself requires causality--things are happening. Whereas the photon hasn't actually changed. We might be inclined to say that it has changed in the sense of locomotion--it was first here (S) and later there (E). But if we're to take the videos seriously, that doesn't work for reasons I already offered to Obi. Light is not just some particle that happens to move at this particular speed such that, by accident, if you move at this speed then time stops from your perspective. Rather, light just moves at "the speed of causality"--whatever meaningless nonsense that is.

Perhaps there is some sense in which the photon does instantaneously cause some effect on earth, but that "instantaneous" works out in different ways depending on the temporal relation of the various objects in question. Things moving faster are related differently than things moving slower, such that the effect of the sun's light on the earth is such that the effect is experienced in what we understand to be a temporal relation eight minutes removed. But now we might be tending back towards a B-Theory of time (per my opening post) . . .

Bah, I'm sort of thinking "out loud" at this point. I think my problem here might be the relation between space and causality. I think I have a good grasp both on the A/T notion of time and the A/T notion of causality. But it strikes me that I've not read anything on the A/T notion of space--at least nothing I can immediately think of. I wonder if it is something that was taken for granted, that absolute space was just assumed. And if so, I wonder if there aren't principles in the A/T notions of time and causality that better account for what space actually is.

edit:

I think I need to revisit Aristotle's Physics. I haven't looked at them in years, honestly, but I feel like I remember learning that he did not have a Newtonian notion of absolute space or time. Can anybody correct me on this sooner rather than later? Google works, but if any of you know chapter verse, that would be extra helpful . . .

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 4:20 am 
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Byblos wrote:
Quote:
Conversely, if the spatial distance between two events divided by the time difference is larger than the speed of light
How does that sentence even make sense? If I said that the distance between two cities is larger than the speed, I would be speaking gibberish.

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 7:02 am 
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Granting the obvious caveat that I'm not a physicist, I don't interpret him that way. Suppose the distance between two cities is 100km and the time difference (how long it takes me to get there) is 1 hr. So the inequality he's asking us to set up is

100km/1hr ≤ 300,000kph

So construed, it isn't nonsense. What he is saying is that two events that are separated by a larger distance than something moving at the speed of light could reach at any given time cannot, in principle, be causally related with respect to that given time. You could work that out at any distance, by the way. Take our two cities that are 100km apart. In our daily world they could always be causally related. But that's because in our world things that happen in milliseconds or less or all but simultaneous. But take an experiment where Event A happens in Eastown at t1 and then Event B happens at Westown at t2, and the time difference between t1 and t2 is .0003 seconds. That is the minimum length of time that could separate the events between the two cities and they remain in principle causally connected. So some A in Eastown at t1 and B at Westown at t2, where t1-t2 is, say, .00003 seconds, are absolutely not causally related. Those separated by .03 seconds might not be causally connected, but there's not a barrier from a physics perspective saying that they are. The separation of .00003 seconds "breaks" causality, because such presumes something has moved faster than causality itself.

And that gets back to my OP. What does that mean, to move faster than causality itself?

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 7:34 am 
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What is the relationship of the sides of a four-sided triangle to the inner angles?

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 8:08 am 
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My point exactly.

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 9:25 am 
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Now this video is really helpful

https://www.youtube.com/watch?v=YycAzdtUIko

He's very imprecise in his philosophical language, and so it's a bit frustrating. But I think some of the facts he presents are helpful. Will comment more later.

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 12:10 pm 
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Going back to the OP, I think the problem with all of this has to do with our definition of "the present." At least for me, the problem is that if I'm not careful I assume a Newtonian notion of both space and time . . . what I might consider a common-sense view (regardless of whether or not, historically, that's been the common sense view). I have to work hard to remember that voids are not really things and that time doesn't exist as a discrete entity. The result of that is that it's easy for me to think of the past, the present, and the future as discrete, real things -- i.e., as in a platonic notion of time. So it's easy enough by thinking about relativity to see that, for some observers, thinks that one regards as past another will regard as future, and that quite literally the order of events themselves can be perceived differently. All of that has to do with your frame of reference and is completely consistent with an A/T notion of time. What it is not consistent with is a Newtonian, or what I consider a common-sense, view of time.

So, again, that's easy for me to see about the past and the future. I have to work extra hard to remind myself that the present is just the same way. I can't define "the present" in a Newtonian sense, as if there were some universal "now." I think it is important to remember that everything really and truly does have it's own now, and due to the way the universe is structured (and this will get us to the wrongly labeled speed of causality, as I far as I can tell), because nothing material moves at this so-called speed of causality but is instead impeded by mass, and because most everything in our daily lives is far larger than quantum level stuff, the bottom line is that our normal lives tends very much to be consistent with regard to our temporal references. That goes back to my comments to CC. It's just a fact that everything in my daily life is so vastly closer together in distance than the speed of light that, and given the scale I normally operate at (inches, feet, and miles; seconds, minutes, hours, days, and years), that everything is so very consistent.

That can make it easy to think of "the present" as this thing that all reality has to share. But that's just not true. If time is the numbering of motion before and after, and if things move, and if things stand in relation to one another and therefore a temporal relation to one another, then everything really does have it's own time. "The present" is massively subjective. It is objective insofar as I truly am in act at this way, but it puts the cart before the horse to say that I am actually this way right now. More precisely, that's trivially true. That's what "right now" is. It is the way I actually exist. The future is the way I will or could exist when that potentiality gets reduced and the past is the actuality that was that no longer is. So "nowness" derives from causality. That is, the present itself derives from my state. It isn't vice-versa. But then you have to add the very important fact that I don't perceive my "nowness" in the now. The very act of perception is a change, and thus to perceive what I am now is, by the very nature of the perception, to perceive something that was. And thus, in a very real sense, my present experience is necessarily and always the past.

By simple analogy, we all know that the stars, as we see them today, is not how they are today. We're actually looking back in time. But in the same way, my perception of "now" is what was, not what is. So the subjective present is the objective past. The objective present is absolutely imperceptible due to the nature of human intellect, or indeed of any intellect that does not immediately apprehend some reality (which I take to be everything but God, although perhaps someone could argue that aeviternal beings could so perceive reality--I haven't studied that enough to know).

What I think I'm seeing then, is that "the speed of causality" is very poorly worded--not true as stated, in fact. It's meaningless, for all the reasons I've been arguing. What we ought to say is that, given the nature of mass itself there must be cosmic speed limit (in short, it is not true that the distance between two objects is infinitely divisible, and that must be true (so see Xeno's Paradox - or this Space Time video that explains it). Just like at a certain "closeness," reality becomes "blurry," at a close enough measure of "the present," reality becomes "blurry." That is, again, the closer you get to that speed limit, the blurrier things get.

I think that's what this whole "speed of causality" thing is actually trying to measure. At this speed of light/causality, what you actually have is unimpeded change . . . the effect of A on B without anything (i.e., mass) to hinder it. At such a speed, causality really would be instantaneous. And, indeed, as I think is well known, if the speed of light were infinite, then there would be no mass, no universe, no time, because everything would be instantaneous. Ironically, Newton's absolute present would leave us with an instantaneous and so non-existent universe! But start adding mass and you start adding impedance to change. And that makes sense, as Aristotle and Aquinas tell us that for any hylomorph, the whole is moved by the parts. The more mass, the more parts. The more parts, the more has to be moved for the whole to move. The more change necessary, the more time passes. Thus, the larger the object, the slower it goes, i.e., the more time it experiences. That's why a photon, which is massless, wouldn't experience any time (to anthropomorphize that a bit).

I claim, then, that causality does not have a speed, contrary to the original video. Rather, what happens is that we can calculate the rate of change for that which has no mass and then assign it a "time." The time can only be assigned because we are massive (that is, we have mass, not that we are huge). The cost of this is that I have to give up my notion of "the present" as some absolute thing, because I only have a "present" insofar as I have time, which is to say, insofar as I am a massive thing that is changing.

I also am wondering if this isn't what underlies some of the difficulties we have in discussing QM with the difficulty of measuring a particles' velocity and position with precision. What I just said above would presume that photons (say) don't actually have a present--at least, not from our perspective. It is certainly true that the photon is in act, and so has an objective present, but it can't have the subjective present I discussed earlier for all the reasons I've already mentioned. What that means that when I ask where a photon is "right now" or I ask where it is "right now" I'm asking it for it's temporal relation to my present. But that is just impossible. It's impossible to get both, anyway. Because if the photon has no present (for me), then in measuring it, I am giving it a present (for me). But since having a present presumes a causality, I have to ask what it was that caused it to have a present for me. And that cause is . . . ME! In measuring or observing it, I gave it a temporal relation. (And given the important of the Planck constant in the connection between the objective and subjective present (again, see the video linked above), I'm not surprised when Heisenberg gets his uncertainty principle via the said constant.)

So I guess I lied when I said I think the two are easily reconcilable. They aren't. But bottom line is that as far as I can tell, it's important to let go of a universal notion of "the present" and to recognize that the phrase "speed of causality" is meaningless, that instead, what we're measuring is our perception of unimpeded change, how that looks to our frame of reference. Taken one way, it really will be absolute for any frame of reference, because non-impeded is just non-impeded! But taken another, from the thing not being impeded (i.e., a photon, or something inside a singularity), it really would be different.

If I'm anywhere near the ballpark of being right, what blows me away about this isn't that we can understand these modern scientific claims in light of Aristotle and Aquinas, but rather that these principles (not the math, though) seem embedded in their very thought process. In other words, I don't think I'm reading science into the A/T theory of time, here. Rather, I think think this is all just a rather natural outworking of the A/T theory of time (and so causality).

Or, of course, everything I said above could be utter nonsense . . . :mrgreen:

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 1:08 pm 
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Way over my head to comment on specifics but here's what my simple mind surmises from all of this. Inertia doesn't exist. The only constant in the universe is motion (how's that for a rational oxymoron?) Objects with mass experience change differently (from one another) depending on their mass and frames of reference, whereas mass-less objects change instantaneously (i.e. frame of reference is meaningless). What that has to do with causality or A/T theory of time I haven't a clue. I'll leave that up to you. :D

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 Post subject: Re: The Speed of Causality
PostPosted: Fri Apr 28, 2017 5:27 pm 
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Here's another video that gets at some of the stuff in my longer post above. It's a (lot of) bit easier to grasp than the PBS Space Time stuff.

https://www.youtube.com/watch?v=ACUuFg9Y9dY

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 Post subject: Re: The Speed of Causality
PostPosted: Sat Apr 29, 2017 12:15 am 
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Obi-Wan Kenobi wrote:
What is the relationship of the sides of a four-sided triangle to the inner angles?


They're the same as usual, and yet also completely different... ;)

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