Everything posted by davidm
davidm added a topic in ExploreE-mail to PetkovHere is an email I’m sending to Professor Vesselin Petkov on his essay, which I am trying to link to in a standard way, but appears the new software precludes this. Let me try to just copy-paste the link below:
Dear Professor Petkov:
Recently I read your essay on free will. I am not a scientist or a philosopher, but a layman who has read widely in both fields. I have also read all of your papers archived at the Phil Sci site.
You hold that free will is not possible in a four-dimensional world. You do not specify what kind of free will you are talking about — compatibilist? Libertarian? Some other kind? — but I imagine you must mean that any kind of free will is impossible in Minkowski spacetime.
I believe you are mistaken, and will present my case shortly, but first a few preliminaries.
I think it a bit odd to say, as you do, that all moments in time are given “at once” in a 4D world. This implies that all times happen at the same time, which is akin to saying that all different places in space are “here.” I think it better to say that in 4D world, spacetime events each have their own unique four coordinates. It’s not that all events in spacetime exist “at once,” but rather that all such events are ontologically on a par. Thus Socrates exists, but he exists in the distant past relative to what you and I call “now.” His now is as real as our now, but they are spatiotemporally separated.
You take issue with the name “theory of relativity.” It is my understanding that Einstein himself regretted the name, and had wished it to be called the “theory of invariance.”
You quote Weyl:
“The objective world merely exists, it does not happen; as a whole it has no history. Only before the eye of the consciousness climbing up in the world line of my body, a section of this world ‘comes to life’ and moves past it as a spatial image engaged in temporal transformation.”
Clearly, Weyl is trying to account for the illusion of passing time, which must be an illusion in a 4D world. But not only that, I would have to say that motion itself is illusory in such a world. But according to Weyl, in a 4D world, something does move: consciousness somehow “climbs up” the world line, or world tube. How does consciousness achieve this magical feat, in a block world where nothing else ever changes and everything that ever was, is, or will be, is simply given? This might be OK as a kind of metaphor to explain the illusion of passing time, but it seems completely inadequate as a scientific theory or even hypothesis: It is wholly non-explanatory. It seems to carve out a special place for consciousness, which may in fact be the case; but no explanation of what this special place is or how it works is given.
In a similar vein, you write:
“… the physical world is a four-dimensional block Universe and it is the consciousness which moves along the worldtube of our body (reading the information stored in our brain at different moments of time) and creates the illusion that there is an objective distinction between past, present and future (i.e., that time really flows).”
Again, I find this deeply puzzling. It seems you are speaking metaphorically rather than scientifically or even philosophically. How does consciousness move like this? I have this impression of a flashlight slowly drifting along the world tube and from moment to moment “lighting up” previously stored conscious thoughts, but plainly if this is so, then the flashlight must be above and beyond the 4D world — or so it certainly seems to me. What I would say, rather, is that consciousness does not move along the world tube, and literally nothing is “climbing up” the world tube. Rather, consciousness is stored at every temporal part of the world tube, and each part experiences its own moment in time as being the indexical “now.” A temporal part of me is experiencing this date (March 19) as “now,” but all my other temporal parts at every spatiotemporal location between my boundary conditions (birth and death) is doing exactly the same thing.
We do not really know what consciousness is. Some people still subscribe to metaphysical idealism rather than metaphysical naturalism: Naturalism holds that consciousness supervenes on matter, whereas the idealists hold that matter supervenes on consciousness. A proper solution to the so-called Hard Problem of Consciousness may be needed before we can explicate how consciousness precipitates the illusion of passing time in a 4D world.
The main point I now wish to defend is that I do not agree that the 4D world precludes free will.
In your essay, you imply that only in a 3D world would some kind of free will be possible, but not in a 4D world.
Let’s conduct a thought experiment. We put two worlds side by side. One world is 3D world and the other is a 4D world. Let us say that each of these worlds comprise a complete history from the Big Bang to a supposed Big Crunch. Godlike we stand above these worlds at the Crunch and look back across the sweep of their respective histories. In so doing, let us imagine that each history is identical down to the minutest detail, and though we are Godlike, we do not know which world is 3D and which world is 4D.
In this case, how would our hypothetical observer tell the difference between these two worlds? In the 3D world we suppose free will holds, but not in the 4D world. Yet, their histories are exactly the same. There is no way to tell which world has free will and which lacks it.
The point is that regardless of whether we live in 3D or 4D world, there is only one history. (We will put aside ideas like quantum Many Worlds; such ideas are irrelevant for the purpose of this discussion since even if such worlds exist, we ourselves only experience one world and one history.) If there is only one history in either 3D or 4D, and the history is the same in our thought experiment, how can we say that one history encompasses free will and the other fails to do so?
You say that in 4D world, the future history of the world is pre-determined, like a film in a can. This implies that the history of the world is necessary. But it's not. The history of the world, whether in 4D or 3D, is contingent. There are a limited number of necessary truths: triangles have three sides, no bachelor is married, etc. All other truths are contingent: they could have been, or could be, otherwise.
Today I am typing this e-mail to you. Ten years from now, if I am still alive, I will likely be doing something very different: eating a burrito, say. In our thought experiment, let’s say I am eating a burrito ten years from now. I am eating a burrito both in the 3D and 4D version of reality. Why am I freely eating it in 3D but not in 4D? In fact, I am freely eating it in both!
As today I type this freely, so in existent (under 4D) reality, ten years from how I am eating a burrito freely. (Or, more properly, in 4D, a temporal part of me is typing this now, and a different temporal part of me is eating a burrito ten years hence.) What’s the problem? As I see it, the problem is that under your version of free will, you implicitly smuggle in what I hold to be an illicit premise: that in order to have free will, we ought to be able to CHANGE the future. This is simply wrong, regardless of whether the world is 3D or 4D. It cannot be emphasized strongly enough that whether the world is 3D or — as I believe you have proved — 4D, NO ONE CAN CHANGE THE PAST, PRESENT, OR FUTURE. But free will does not require that we be able to change anything!
Rather, by our free acts, whether in 3D or 4D, we MAKE the past, present, and future, BE what it was, is and will be.
It does not matter if, under 4D, the world is “predetermined” like a film in a can. Each frame is one single way, true enough. Indeed, that is also the case in 3D, since in either case there is only a single unitary history. But WE OURSELVES determine the content of each frame, in both 3D and 4D. The ontology of the world does not affect free will once it is plainly understood that free will does not involve “changing” anything at all.
Here is a different example. We know for sure that the past is fixed. This is true under both 3D and 4D. Now let’s suppose I have a time machine that can take me to the past. I enter it, and go to the past. Can I change the past? And, if I cannot, does that mean I lack free will?
The answer is that I cannot change the past. But this does not mean I lack free will. Suppose I traveled to a point in the past before I was born. This means that at the time of my birth, a future temporal part of myself FREELY did in the past, even before I was born, exactly what he did there. He didn’t change the past. Rather, by his free acts, he helped make the past be, exactly what it was. And so it is with the present and the future.
It’s true I can’t change the future in 4D. But I can’t change it in 3D either! It doesn’t matter. I don’t need to change the past, present or future. I just need to make it be, within the limits of my power, what it actually is from moment to moment. Understood this way, free will, if it exists and isn’t barred for some other reason (we are all really wind-up robots, etc.), is indistinguishable under either 3D or 4D. If it’s valid in one it’s valid in the other. The ontology of the world has no bearing on free will. That’s why, in the thought experiment mooted above, the 3D and 4D worlds really are — when it comes to free will — indistinguishable! Thus I feel we should take the eliminativist stance when it comes to free will in 3D and 4D. The “problem” is eliminated.
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davidm added a topic in Read11-22-63I wonder if Steven King or his publisher knows that King’s novel “11-22-63” is online, in full and for free. I can’t imagine that they would give permission for such a posting, for why would they? Hulu is soon streaming a mini-series based on the novel, and the trailers were captivating. It made me want to read excerpts of the novel, which I’d never read, and I looked for them online. Instead I found the whole damn thing. Perhaps King should travel back in time and prevent his novel from being illicitly posted in the first place.
Such time travel is the premise of “11-22-63,” in which a disaffected and recently divorced high school English teacher, Jake Epping, is charged by a friend with the task of traveling back in time to prevent the assassination of John F. Kennedy. The novel is a real page-turner — or page-clicker in this case. Long as it was, I seemed to have clicked through it no time and read it in full. Sorry, Mr. King, no royalty from me.
It’s a great yarn, with interlocking subplots and enough twists and turns to make the reader dizzy. Jake’s mission to the past isn’t made any easier when he falls in love with a beautiful librarian after arriving in Texas.
Can Jake Epping change the past? Can he prevent JFK’s assassination?
King comes up with what is, so far as a I know, a novel twist on the old time travel theme: the past does not want to be changed, and it fights you every step of the way.
Here King is on to something, but he doesn’t take it the necessary step further: It’s not just that the past doesn’t want to be changed — it cannot be changed. It cannot be changed as a matter of logic. Hence Jake’s mission is doomed from the get-go. Nothing in the past can be changed; not even the tiniest detail of it. However, this inconvenient fact, once recognized and acknowledged, would make for a pretty boring novel, and King is never boring.
Is travel to the past possible at all? It might be. Nothing in logic forbids such travel, and it may even be physically possible. All that logic forbids is conjointly traveling to the past and also changing it. The very act of traveling to the past does not, as one might suppose, change the past; rather it makes the past be just what it was: a spacetime region with a time traveler from the future in it. The time traveler was always there. His presence did not change anything.
In King’s novel, the protagonist finds a path to the past. I wonder if King knows that this has scientific warrant? Perhaps he does, but decided that introducing the concept of the Gödelian closed time-like curves would daunt the reader. In any case, I felt his failure to explicate his “rabbit hole” in terms of Gödel’s solutions to general relativity was a missed opportunity, for his “path” idea is just how past-directed time travel work, if possible at all. This is because all of us travel in spacetime jointly, not just space or time singly, and some such paths can indeed lead to past-directed spacetime locations.
The novel’s flaw, from a philosophical perspective, is that early on King broaches a discussion of the Grandfather’s Paradox but offhandedly dismisses it: “Why would anyone want to do that?” a character asks, referring to the the possibility of someone going back in time and killing his own grandfather. What King fails to notice, though, or (as I think) chooses to ignore for the sake of a good yarn, is that all efforts to alter the past are thoroughly contaminated by the Grandfather’s Paradox, which is just a special case of a general logical principle.
In the well-known paradox, a man goes back in time to kill his own grandfather before the time traveler’s father is born. If he succeeds, the time traveler will never be born. But if the time traveler is never born, he will never go back in time and kill grandfather. But if grandfather is not killed, the time traveler will be born after all. If he is born, he will go back in time and kill grandfather, and then … the problem is obvious.
It is thus logically guaranteed that the time traveler will not kill grandfather, no matter how hard he tries.
But Jake Epping’s going back in time and saving JFK is obviated by the exact same logical structure of the Grandfather’s Paradox. Suppose Jake goes back in time and prevents JFK’s assassination. In that case, in the future, Jake will not go back in time to save Kennedy, because Kennedy was never killed and so Jake has no reason to go back and save him. But if Jake doesn’t go back in time, Kennedy will be killed. If JFK is killed, Jake will go back in time to save him. But if he saves him … etc. It’s the Grandfather’s Paradox all over again, and it can’t be avoided.
The larger philosophical point is that time travel to the past is no different from time travel to the future — it’s just more peculiar. Just as we cannot change the past, nor we can change the present or the future. Rather, by our acts, we make the past, present and future be what they were, are, and will be. We never actually change anything.
When Jake Epping was born (in 1975, in the novel) his future self had already done, what he had done, in 1963. Those things included failing to prevent JFK's assassination, given that when Jake was born, JFK had in fact been killed 12 years earlier. Jake’s mission is logically futile even before he undertakes it. The poor man could have refused his friend’s request on grounds of pure logic and saved himself a lot of time (five years) and trouble (he gets into a lot of it). All he had to do was crack a logic textbook! See how useful philosophy can be, after all?
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davidm added a topic in ExtendETs found?The Most Mysterious Star in Our Galaxy
Phil Plait discusses.
Someone out there may be building Dyson sphere right now, and not too far away, either!
Whoever they are, we'll have to work them into Pantheon, Heretic.
ETA, I can't get the first link to work properly; i.e, to look the way the Phil Plait link looks. No idea why. It did have the close url tag when I set it up, but on posting the close tag vanished and this is what's left. But you can click on the raw link and get the Atlantic article.
And again, I really, really wish we could have the "Preview Post" function restored.
ETA: Fixed it for you.
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