[O'Brien to Winston Smith]: 'Is it your opinion, Winston, that the past has real existence?'
Again the feeling of helplessness descended upon Winston. His eyes flitted towards the dial. He not only did not know whether 'yes' or 'no' was the answer that would save him from pain; he did not even know which answer he believed to be the true one.
O'Brien smiled faintly. 'You are no metaphysician, Winston,' he said. 'Until this moment you had never considered what is meant by existence. I will put it more precisely. Does the past exist concretely, in space? Is there somewhere or other a place, a world of solid objects, where the past is still happening?'
'No.'
'Then where does the past exist, if at all?'
'In records. It is written down.'
'In records. And- ?'
'In the mind. In human memories.
'In memory. Very well, then. We, the Party, control all records, and we control all memories. Then we control the past, do we not?'
I’m not sure who the intended audience of this upcoming book is, but if it is laypeople, I feel as though the level of explanation is too advanced. Eg:
> Just like a ball doesn’t change if you rotate one direction of space into another, Maxwell’s equations don’t change if you rotate one direction of space into time.
> So, Minkowski said, we just combine space with time to a 4 dimensional space-time, and then we can rotate space into time just like we can rotate two directions of space into each other. And that naturally explains why Maxwell’s equations have the symmetry they do have.
I have read, enjoyed, and understood a lot of popular physics books. But none of that makes a lick of sense to me. Either I’m dumber than I thought (probably), or I’m not the right audience, or this is a poor explanation.
The article does not even discuss the obvious alternative that is perfectly consistent with relativity: all events in your past light cone "exist" (a better term would be "are fixed and certain"). This avoids all of the issues mentioned in the article while not committing you to the "existence" of anything that might not be fixed and certain based on the information you have at any particular time.
What always amazes me about discussions like this is how even physicists who are experts in relativity fail to see the obvious implications of the fact that, in relativity, spacetime is divided into three regions instead of two. Instead of just "past" and "future", there are "past light cone", "future light cone", and "spacelike separated". "Past light cone" and "future light cone" behave more or less like our intuitive concepts of "past" and "future"--the past light cone is what is fixed and certain and can't be changed, and the future light cone is what can possibly be changed based on things we do here and now. But the spacelike separated region is not like anything in our intuitions, since it is not fixed and certain as far as we know here and now, but we also can't do anything here and now to change it.
But instead of recognizing all this and considering its implications, discussions like this article talk as if the only way to divide spacetime up into regions is "past" and "future" separated by a "now" slice (and the "now" slice is of course frame-dependent so it can't have any physical meaning), or to talk as if the only thing that "exists" is the single point in spacetime that is our "here and now". It's disappointing.
The author hasn't neglected to consider light cones – she literally describes them in her post, as evinced by her mentioning 45 deg lines on a spacetime diagram, causally connected/disconnected events, etc.
Of course you have described a perfectly good way of thinking about the past/future (and to your credit, she surely should've included what you described). But in her defense, what you have described is also the most obvious explanation consistent with special relativity – the "past" and "future" outside one's line cone cannot be objectively defined, as you could always (hypothetically) boost to another frame in which the disconnected past becomes the disconnected future (and vice versa). Undoubtedly the author is aware of this fact, so I assume the purpose of this blog post was simply to motivate other hypotheses about the nature of time.
> The author hasn't neglected to consider light cones
She describes them, but does not consider their implications for the structure of spacetime.
> you could always (hypothetically) boost to another frame in which the disconnected past becomes the disconnected future (and vice versa).
No, you can't. That's the whole point of looking at light cones instead of spacelike "now" slice. Light cones are invariant; they're the same in all frames. Spacelike "now" slices are not. Also, you can't do a Lorentz boost that turns "future" into "past" or vice versa.
I think OP means “disconnected past” as the spacelike-separated region south of the “now” slice. Boosting could transform points in this region into the spacelike-like separated region in the “future” (i.e. the “disconnected future), no? The points are not transforming across the light cone boundary, just across the arbitrary “now” plane.
Yes, this is what I meant. By "disconnected" I meant causally disconnected, i.e. spacelike separated. Sorry for not making that clearer!
And yes, you can always boost to a frame such that the "order" of spacelike separated events will change (i.e., reverse which event is above and which is below a line of simultaneity). Since you can't objectively say which event happened first, they must be unable to influence each other, hence "causally disconnected".
I don't think physicist really misinterpret this if you asked them. The problem is, as you say, that the "past" and "future" only have a physical meaning inside your own light cone. As alluded to in the video, you cannot compare space and time differences without defining a common reference frame, so it doesn't really make sense to talk about a past and future in spacelike separated regions of spacetime.
Special relativity is great because it produces some very non-intuitive conclusions about our Universe, and it's always lovely to explore new mind-bending questions arising from these conclusions, especially in outreach pieces like this. I think conceptual discussions like these can be very enlightening, but its not something that keep a lot of physicists up at night.
The problem with that is that, then, what exists (in the unrestricted sense of 'exist' the OP is after) becomes event-relative: not everything that exists from your vantage point exists from the vantage point of someone in Alfa Centauri or whatever. You may want to live with this 'metaphysical relativism', but it is hardly better than the solution offered by the OP, which is the standard one.
> what exists (in the unrestricted sense of 'exist' the OP is after) becomes event-relative
Well, of course; that's how we already use the term "exist" in ordinary language. We say that our past of today "exists", but tomorrow does not, at least not yet. But tomorrow, we'll say that what we now call tomorrow does "exist". So our ordinary language concept of "exists" already takes into account that what "exists" changes over time.
The commonsense tensed 'exist' is not a good model to 'only my light cone exists'. The former says that events in my causal past and future do not exist, for example. The latter only makes sense as a proposal about some unrestricted notion of existence. More or less: what is the smallest catalogue of entities I need to commit myself to, if I want to make sense of the science?
Or we can reject ontological anti-realism. That is, what "exists" in the first place are linguistic conventions constrained by physics, our understanding, and practicality.
Please note the inverted commas around 'exists' in my comment. They are there for a reason.
I can imagine the layman ascribing some mystical quality to ontological anti-realism, but, ironically, the view acts to dispel the mystical quality of uncritical "existence" claims that many take for granted (much like theism, moral realism, etc.).
In General Relativity events in your past light cone can be events in your future light cone. In Loop Quantum Gravity, the idea of a past and future lightcone become discrete and entirely local to a specific element of spacetime. Consequently, assigning elements of a past light cone to "reality" becomes ambiguous: _which_ past light cone?
At the level of LQG all you can describe is relations between points of spacetime and the idea of past/future becomes ambiguous.
Another modern approach to quantum gravity (energetic causal set theory) does re-impose a sort of global ordering (in the sense reality is a series of states updated with a single rule depending on the momenta of previous realizations of the state elements) but in that theory the past really is gone. This is similar to the (more classical) approach of Shape Dynamics (a general relativity-like theory of gravity) where all that relates a "current" snapshot of time to a "previous" snapshot is that it minimizes a particular mathematical quantity. I am definitely not an expert in LQG or GR or Shape Dynamics, but the story isn't quite so obvious and simple as you make it out to be and that may be why you are unsatisfied with how physicists talk about it.
> In General Relativity events in your past light cone can be events in your future light cone.
Only in spacetimes with closed timelike curves, such as the Godel Universe. Those spacetimes are considered by physicists to not be physically realistic.
All physically realistic spacetimes, including all of the ones we use to actually model things in the actual universe, are globally hyperbolic, and in a globally hyperbolic spacetime the same event cannot be in both the past and the future light cone of some other event.
They appear in the Kerr metric, which isn't particularly exotic except for the fact that realistic spinning black holes clearly don't have all the symmetries of a Kerr black hole. I would not be surprised to learn that the question of CTCs in realistic spinning black hole solutions is open, but I am not an expert in General Relativity. We certainly use the Kerr black hole solution to model things in the actual universe.
At the very least, the fact that CTCs appear in solutions to GR but seem physically implausible suggest that the basic physics of time are not fully understood (as do the other more outre theoretical avenues I pointed out). I think its pointless to be glib about the reality of the past, given that fact.
Only inside the inner horizon, which virtually all physicists working in the field consider to be unphysical because of the "infinite blueshift" effect at the inner horizon and the fact that it is a Cauchy horizon: you actually can't predict what will be inside it based on any data from outside it. (Note that the outer horizon, like the horizon of a Schwarzschild black hole, does not have these properties.) The prevailing opinion seems to be that the interior of a rotating black hole will end up being qualitatively similar to the interior of a non-rotating black hole, with the inner horizon and region inside it of the idealized Kerr solution being replaced by something that looks more like a Schwarzschild interior. (And of course if we figure out quantum gravity that might change things even further.)
> We certainly use the Kerr black hole solution to model things in the actual universe.
We use its exterior to model things in the actual universe, yes. But none of those models depend on the interior having the properties that the idealized Kerr solution has. They certainly don't depend on their being CTCs somewhere inside.
> the fact that CTCs appear in solutions to GR but seem physically implausible suggest that the basic physics of time are not fully understood
No, it suggests that, as with any physical theory, you have to look at actual data to see which of the infinite number of mathematically possible solutions to the theory's equations describe things that actually exist. All of the solutions that describe things that actually exist are globally hyperbolic and do not contain CTCs or any other weird "time" properties. That suggests that, as far as things that actually exist go, we have pretty good models of "the basic physics of time".
That’s my favorite way to think about this as well, but it’s very geometric and maybe not so intuitive to explain in a video that targets a non-mathematical audience. That physicists aren’t aware of this interpretation might be a bit of a stretch, that’s at least not been my experience.
This sounds very interesting, thank you for sharing. Could you recommend any resources to learn about these three regions, ideally for someone without formal physics training?
Penrose's The Emperor's New Mind contains a good layman's discussion of it. (It also contains a good example of a layman's work that makes the same mistake the article under discussion here does: even after going to all the trouble to explain in detail how the three regions I described work, and how "now" slicings, unlike the three regions I described, are frame-dependent and don't have physical meaning, he then makes an invalid argument for the "block universe" viewpoint that depends on ignoring the three regions and treating "now" slicings as though they do have physical meaning. It's an excellent example of how even experts of the stature of Penrose can get things wrong.)
I don't understand your objection to the slicing procedure.
The central assumption is that for a reasonably physical spacetime there exists a unique maximal globally hyperbolic solution to the field equations, justifying the use of the initial value formulation of General Relativity. [aside: [1]]
Once we do that we can take any arbitrary spacelike hypersurface Σ and in ADM-ish vocabulary observe the compact closure conditions (Σ has a spacelike geodesic from every p in Σ to every other p in Σ; every maximal spacelike geodesic has a nonempty open segment in Σ; every maximal timelike geodesic intersects Σ), the "thin" condition (no nomepty segment of a null geodesic is found in Σ), and a variety of causal conditions (e.g. no timelike geodesic connects points in Σ; no maximal timelike or null geodesic intersects Σ more than once).
One can translate these features to your cones-only view. On a Minkowski diagram with p at the origin, Σ can have any shape or orientation compared to the light cones as long as p -- and nothing else in either of p's light cones -- appears on Σ. We can do the same for any other p in Σ, or we can decide whether the origin of any pair of light-cones is in Σ or not. We can also probably build Σ by hand from a principled choice of available light-cones. (One would be tempted to call that "initial data").
Is Σ physical? Of course not! But it can be used as the basis for physics that describes point-coincidences on other spacelike hypersurfaces, which we can then verify.
> The future light cone is what can possibly be changed based on things we do here and now
In which of your three regions do we find the freedom to do this?
Is here-and-now not fully determined by the "fixed and certain" content of its past lightcone?
Is the "we" part of "what we do here and now" describing a point on the manifold or is it describing a set of points on the manifold? Choose a point somewhere in the middle of "we" -- in which of the three regions are its other points?
I struggle to answer that without thinking about an extended "we" with many entries in Σ (including photons (and other carriers of body forces) bouncing around within or even passing through the extended body). Maybe it's much easier for you.
I wonder how you'd do if you were to think of grossly non-Eulerian (and even non-timelike) observers in a Big Crunch universe. In a Big Bang universe all points are in the future light cone at BB; in a BC universe all points are in the past light cone at BC. At every other point, only some points are in the two lightcones at that point. We get a BC from a time-inversion of our BB->approx de Sitter universe (e.g. for an observer with differently-aligned arrow-of-time). Assuming a long period of matter sparseness, in a BB->BC universe, we also get a ~BC universe if we cut away the expanding part; if we cut away the recollapsing part, we get something that's hard to distinguish from a BB->~dS universe like our own. In a BB->~dS universe I think we'd agree that the future light cones of two observers coincident at p can eventually fully separate. Can we agree that in a BC universe the past light cones of two observers at p can be at least somewhat, or even (practically) fully, non-overlapping (our observers need not be either "Eulerian" comovers with the metric contraction, and can even move lightlike, and there can be a cosmic deflation just prior to the big crunch)?
In an ADM(-like) picture we can fairly straightforwardly use ancestor slices of Σ in the foliation and decide that a pair of photons will be at some point p on Σ. I also think it makes a slice through a spacetime-filling electromagnetic field easier to think about, ditching the idea of bare photons as independent objects. Again it doesn't matter about the timelike direction of the slicing, and one might want to recalculate slicing along some other choice of timelike axis to try to spot coordinate artifacts. However maybe you might object that if we don't have full data for the ancestor of Σ, we're somehow not better off than in the final sentence of your second paragraph.
- --
[1] Weaker causality, such as stable causality in the sense that arbitrarily small metric perturbations don't give rise to CTCs, can still be used but at the cost of solution uniqueness, and weaker still at the cost of smearing out the Cauchy surface so that initial data is not all at t=0 but in some function defined over 0 >= t >= -V^{-1} where V is the scale of strong causality violation.
> I don't understand your objection to the slicing procedure.
It's simple: any "slicing" is frame dependent. And relativity says that things that are frame dependent do not have any physical meaning.
> The central assumption is that for a reasonably physical spacetime there exists a unique maximal globally hyperbolic solution to the field equations
Yes, but globally hyperbolic spacetimes still do not have unique slicings. There are still an infinite number of possible slicings, corresponding to the infinite number of possible inertial frames in standard SR.
> In which of your three regions do we find the freedom to do this?
If the universe is fully deterministic, then in one sense of course there is no "freedom" to change anything. But we don't know that the universe is fully deterministic (and QM strongly suggests that it isn't). But whether it is or not, the distinction I described is still there and still valid, since that distinction is about what we know at a particular event in spacetime.
> In a Big Bang universe all points are in the future light cone at BB
No, they aren't. The Big Bang is not a single point. It's a spacelike line. There are an infinite number of causally disconnected points one "instant" after the Big Bang.
Similar remarks apply in time reversed form to the Big Crunch in spacetimes that have it.
Why would (cosmological) t=0 be a line rather than a point, a 3-volume, or some even weirder non-Lorentzian structure? I can't think of why it would be a line other than (reaching here) nonvanishing vorticity (in either the sense of the Raychaudhuri equation or because of ~axisymmetry with spin), and those aren't features of the standard cosmology.
Obviously I've seen Penrose diagrams with the BB drawn out to look like a horizontal line, but have never taken that to be anything other than for legibility or print-reproducibility reasons, similar to the dimensional reduction of the diagram itself. I would be grateful for a reference with explanatory text if you think this is wrong.
Absent published authority, I think you could also take this up with Pössel (Max-Planck-Inst. Astro. Haus der Astronomie) who by sheer coincidence ran a related twitter thread <https://twitter.com/mpoessel/status/1551119783315251200> in which he writes (among other things): " ... 23/ ... Let's forget about the hot Big Bang phase, pretend that 24/ all the galaxies taking part in cosmic expansion are point particles corresponding to galaxies we see in the observable universe today were at one and the same location. 25/". @johncarlosbaez has been all over that thread on Twitter too, and would probably engage with your it's-not-a-point-it's-a-line point. I am pretty certain that Pössel means we ignore the "hot Big Bang phase" to mean not just the first few minutes (up to the synthesis of helium) (which is a fairly common time frame for "hot Big Bang") but up to early structure formation, and that he'd clarify if asked.
I agree that in the standard cosmology there are an infinite number of causally disconnected points one "instant" after the Big Bang, but don't see how that can't follow from the standard BB singularity.
Of course a BC universe is not standard cosmology, so alternative final shapes don't raise my eyebrows at all, unless you wish to argue that in General Relativity, no BC universe can even in principle have a point wherein all other points are in its past light cone.
All that said, I'm not sure why you're objecting to slicing as having a dependency on choice of coordinates. I did write that \Sigma is not physical. I will now write that it is very convenient to calculate in some set of coordinates, and that it is possible not to fall into holes (pardon the pun) while doing so.
Finally, I'd like to turn on its head your second sentence. Relativity allows some physical distributions of stress-energy to pick out a meaningful set of coordinates. (as has been known in cosmology for many years. cf. <https://arxiv.org/abs/1211.6338> §2 notably p 4)
Just to be provocative (in reality I agree with you that light cones are more fundamental objects than any spacelike hypersurface, and that light cone surfaces are physically meaningful at least in the local neighbourhood of p) I'll drop in some Bob Geroch: "[Special Relativity] emerges as just one more physical system. It consists, just like the others, of certain fields subject to a certain system of first-order, quasilinear partial differential equations. The causal cones of special relativity (which reflect the speed of light) have no special significant over the causal cones of any of the many other such systems in physics." <https://arxiv.org/abs/1005.1614>
(That democracy of causal cones paper is surprisingly relevant to some of the conversations you are running here tonight, particularly §2. I think you might especially enjoy the last paragraph on p. 6, notably its last two sentences starting "We note that, quite generally, C is a nonempty, open convex cone of tangent vectors...". In the context of our discussion, you might not enjoy the part starting at the bottom of p. 7 to the start of §3 :-).)
> Relativity allows some physical distributions of stress-energy to pick out a meaningful set of coordinates.
More precisely, with certain distributions of stress-energy, computations become much simpler in particular coordinates. But that does not mean the coordinates have any physical meaning. If there are any actual invariant properties of the spacetime that particular coordinates make more evident, those properties can always be expressed in coordinate-independent terms, for example in terms of Killing vector fields.
> which I think is wrong for the standard cosmology.
I have no idea why you would think that, since the very paper you link to explicitly shows diagrams in which the Big Bang is obviously not a single point but a spacelike line.
> Why would (cosmological) t=0 be a line rather than a point, a 3-volume, or some even weirder non-Lorentzian structure?
Because that's what you get when you take the appropriate limit.
> Obviously I've seen Penrose diagrams with the BB drawn out to look like a horizontal line, but have never taken that to be anything other than for legibility or print-reproducibility reasons, similar to the dimensional reduction of the diagram itself.
You are mistaken. The point of a Penrose diagram is to show causal structure; that is how it is constructed, so that light cones on the diagram exactly match light cones in the spacetime it's a diagram of. That means that if it were really true that the entire universe was in the future light cone of the Big Bang, the Big Bang would have to be a point, and the diagram as a whole would be an inverted triangle that was the future light cone of that point. Which obviously is not the case for Penrose diagrams of the universe as a whole.
As for "published authority", as I noted above, you gave one yourself: the Davis & Lineweaver paper. It agrees with what I have been saying, not with what you have been saying.
> I agree that in the standard cosmology there are an infinite number of causally disconnected points one "instant" after the Big Bang
Then you are contradicting yourself, since this is impossible if the Big Bang is a point. It is only possible if the Big Bang is a spacelike line.
> but don't see how that can't follow from the standard BB singularity.
It does. The issue is not "the standard BB singularity", but your mistaken belief that that singularity is a point. It's not. It's a spacelike line.
I feel like I must be missing something but in the part about the relativity of simultaneity [0] I feel like this is more about the relativity of the observers and the limitations of speed of light than it is about the ontology of time itself?
The definition of "now" as when the light hits the mirror on each side is a "constructed" now, a false now if you may. It takes the light longer on the right side than the left side because she is moving through space, all that tells me is that there is no way to communicate a "now" between different observers because there can't be instantaneous communication between observers, not that time itself is relative or physical stuff itself doesn't have a constant time?
She says in the video that we have to find a way to operationalize how to find a now, to measure it empirically but maybe that's not possible without running a complete simulation after the fact.
But to me it seems not surprising that without instantaneous communication there is no way to create a "now" empirically but that doesn't mean it extends to the ontology of physical stuff itself or time itself. There would still be a time in there (you should be able to see it in a simulation?)
Also for example, if you use sound instead of light, if I'm far away from a sound source (farther than the speed of sound), and another observer is closer to it, we would not be able to use the sound source as a source "now", because I would hear it later. Is this the same type of situation or different? I feel like I must be missing something fundamental here but I'm sort of going out on a limb so please don't slaughter me :P
I suppose so... Not sure about the second part but for the first part I think that comes from the idea that I don't think we've ever empirically or even subjectively observed the universe in any other state than "now". We've never personally nor in a scientific experiment observed any physical system being in more than one state, and that one state has to by definiton be in the "now" (Unless I am mistaken).
So the past and the future states are essentially nowhere to be found in empiricism ?
As for the "here" part I am not sure how to respond to that but it sounds right - any observer has to have contact in some direct way (whether with a scientific instrument or not) to the thing physical system he is observing and as such claiming anything about anything indirect or far away is very hard if not impossible so you get the "here".
My favorite theory about Space and time is the one from Don Hoffman. To summarize, space and time are parts of our interface to interact with other conscious agents , just like our senses of smell, vision, sound. But it is just that, an interface, created by millions years of evolution, and does not shows the true nature of reality, which could be completely incomprehensible to us. Like electricity is incomprehensible to a cat, evolution, which is very power thrifty, provided cats just enough effectives ways to survive and reproduce the way cats do. Same for us.
this is very summarized, his ideas goes much farther, for him the base of true reality could be consciousness :
How does he reconcile space and time being just an interface created by evolution, when evolution itself is a process that only happens because of time?
Well, evolution happening because of time is again how we "understand" it because we have no other ways to. He doesn't say he has the answer to the true nature of time and space, he is a searcher.
Check the vids, it is much better explained than I can do :)
Somewhat related. In the Srimad Bhagvatam Canto 5, a Hindu scripture, it states that the Universe shell (known as the Brahmanda shell) contains all past, present and future events.
OffTopic but curious (not derogatory): Of late, I feel that her video are deepfake with Sabine Hossenfelder speaking from behind. I subscribe to her YouTube channel and I'm a regular. What am I missing?
It's the first time I've seen a video of her and I had the same impression. I think it has something to do with her lack of arm movement (also not derogatory).
She uses green screen a lot to add all the graphics behind and to the sides, which often makes the edge of the person a little random (pixels blink on and off), and the shadows in the graphics may not fall in the same direction as the shadows created by the light on her. In a similar way weather on the news makes the weather person look a bit surreal.
If somehow humans or human ancestors (AGI?) endure to the point they can bend the laws of physics and play back the light cone, I wonder if they'll be interested in revisiting all of us to learn about the past.
To see and touch the dinosaurs, visit Einstein, see everything, even our thoughts. An undetectable time machine that might surround us even now. A traversable field of time. A kind of high fidelity afterlife.
Personally, I think perhaps we are the machine, right now. Everything that has happened now has already happened, and we’re just reliving it. Who knows what iteration of the loop we might be on right now.
Perhaps on our first run free will was much more obvious and abundant, in ways that we simply can’t even imagine right now, kind of like trying to imagine light when you’re born blind. However, the end result still ends up being exactly what you experience now, minus the running dialog of free will.
Our body is controlled by our mind, and our mind is controlled by our consciousness, which is capable of observing and altering our mind’s thoughts. But as far as I can tell, we don’t seem to have any mechanism for “observing” our consciousness. That is the missing freewill component, which may have only existed in our first run.
> But as far as I can tell, we don’t seem to have any mechanism for “observing” our consciousness. That is the missing freewill component, which may have only existed in our first run.
Do you think the "first run" version of yourself would have made your HN comment?
I suspect being able to directly observe consciousness will involve transcending the individual self and end up solving the problem of free will, in that there is no single self to have free will, i.e. consciousness is not tied or confined to any single individual.
Assuming that our individual oerception of experience and agency applies analogously to this greater consciousness, then I suppose so, but I don't know if our narrow minds can comprehend or express the way it operates.
I suggest you the book "Order of time" by Carlo Rovelli. One think I learned by the book is the locality of time. For example imagine one day people living on mars and you wonder what that people doing in this moment. Well is a wrong question. There is no such thing "this moment" in two far placeces
I'm not sure I understand any of this, but I'm trying. Can this be summarized as "for any two points in time, one can always find an observer for whom those two points are simultaneous"?
For any two points in the event space (spacetime), which are causally disconnected (space-like separated, which means one point is not in the light cone of the other), there is always an observer that perceives them simultaneously. There are also observers for which one point precedes the other and vice versa. There are observers that can't see (or cause) one of the points, or both.
Ah, but then it's not especially counterintuitive: causally independent events can happen in any order... The layman's notion of "time" implies causality/irreversibility.
Events that have no causal relation between all have their own little timeline, and it's not troubling or surprising to consider that they are simultaneous / that we examine them in a kind of superposition.
That's right. We've just learned to believe that there is only a past and a future, where the future is caused by the past. In Special Relativity those are just two light cones, but there are always other events. Though, in a flat spacetime they will affect our future, eventually, because we are moving slower than light. In other words, every event is past to some of our future event.
The Big Bang is a different story, because the theory says that spacetime is evolving.
Not entirely relevant, but I think that the Buddhist view of time is interesting, and I guess quite relevant to this block universe idea.
In the Buddhist view, all things are "emptiness", shunyata, without self-existence. This means that there is no fundamental basis with which you can distinguish between things. For example, there is no fundamental property that you can use to distinguish between you and I, or an apple and a keyboard, or even your body and your consciousness. The distinctions are just concepts that we make up and assert that the world fits into it. The Heart sutra says that not only is this true for all the elements that make up our experience, but even also for causal connections such as time.
This view of time was most explicitly emphasised by the Soto Zen philosopher Dogen. He called it Uji, which means "time-being". Effectively he said that being equals time, and that really all time is right now:
[quote]
An ancient buddha said:
For the time being stand on top of the highest peak.
For the time being proceed along the bottom of the deepest ocean.
For the time being three heads and eight arms.
For the time being an eight- or sixteen-foot body.
For the time being a staff or whisk.
For the time being a pillar or lantern.
For the time being the sons of Zhang and Li.
For the time being the earth and sky.
"For the time being" here means time itself is being, and all being is time. A golden sixteen-foot body is time; because it is time, there is the radiant illumination of time. Study it as the twelve hours of the present."Three heads and eight arms" is time; because it is time, it is not separate from the twelve hours of the present.
The way we understand this as Buddhists, is that we are both at the very beginning and very end of our path, at the same time we are both deluded beings and also perfectly enlightened Buddhas:
> Time is not separate from you, and as you are present, time does not go away. As time is not marked by coming and going, the moment you climbed the mountains [walked the Buddhist path] is the time-being right now.
So effectively, we believe that all moments are contained in this moment, because there is no fundamental basis by which we can say that any other moment is separated from this moment. Before and after are illusions, they are just ideas that we have right now.
-- one is in relation to a subject - one an object - I bought this cake for you and I would be incorrect - you and I however - would attend the concert - if you'd like --
The Buddhist response would have been to quietly accept the correction. Maybe learn something. Quarreling without even looking it up is decidedly, how do Buddhists say? "attached".
"Non-attachment", for anyone following, is the core principle of Buddhism.
My experience is the people who say "rude" most frequently have been the most that. I speculate that they imagine so much rudeness around them that they consider their own forgiveable.
Past and future is a trick our mind plays on us. We collect past and future "moments" and believe them to have reality. As we collect these moments the illusion of a timeline emerges. Notice when your body tenses and or emotions and feelings trigger when you are just having thoughts about the past or the future. Why react to thoughts? The mind uses uncomfortable feelings to keep our attention. To break free you just have to sit with all the feelings and accept. Now is all there is.
Yes ! :) shamelessly quoting myself :
"My favorite theory about Space and time is the one from Don Hoffman. To summarize, space and time are parts of our interface to interact with other conscious agents , just like our senses of smell, vision, sound. But it is just that, an interface, created by millions years of evolution, and does not shows the true nature of reality, which could be completely incomprehensible to us. Like electricity is incomprehensible to a cat, evolution, which is very power thrifty, provided cats just enough effectives ways to survive and reproduce the way cats do. Same for us.
this is very summarized, his ideas goes much farther, for him the base of true reality could be consciousness :
https://youtu.be/oadgHhdgRkI
and
https://youtu.be/ds-7sMfJDUw
"
I don't think that a four dimensional view of time is necessary for resolving concerns around the Christian resurrection and how memories/psychology could be maintained.
There are plenty of views that Christians hold, but one of the most popular views (I would guess among the laity, professional philosophers, and possibly church leaders) is substance dualism. While memories are clearly stored in the brain to a degree, or at least influenced by the brain, the dualist typically thinks those memories are also located in and available to the non-physical substance (a soul/mind/spirit/etc) that survives the death of the body. Since those memories survive the death of those neurons, they are never lost.
Another view that was perhaps more popular, and is perhaps also gaining popularity again, usually called idealism, is that there is no physical stuff that exists on its own. Instead, God creates other souls/minds/spirits, and God imagines a physical world, and then gives experiences to those souls/minds/spirits as though they were in a physical world, even though no such mind-independent physical world exists. On this kind of view, the memories at the time of death are remembered by God, or exist within the soul/mind/spirit who was experiencing being that human in that imagined world (this second option is much like the dualist view). And so in the resurrection, God merely needs to have that soul/mind/spirit again have an experience as of being in such a physical world with a body that now has those memories restored, or, if those memories are already located in that soul/mind/spirit, then no extra work is required. The memories are either remembered by God, or were and continue to be stored in the soul/mind/spirit.
A third view, perhaps even less common than the preceding two among Christians, is a kind of materialism, where we have no immaterial soul/mind/spirit, and we are just our bodies. On that kind of view, I would assume the story is that God knows how the body was constructed (including the memories encoded in the brain) prior to neurons being destroyed, and is therefore able to rebuild the body in the resurrection as it needs to be to ensure the right kind of psychological continuity. These kinds of miracles would be trivial for God as described by Christians.
Pretty sure the Bible talks a bit about God existing outside of time (he sees past, present, and future all at once or some such), so I always figured the model was "God exists outside of our universe much like a programmer who exists outside of his simulation, but can step forwards and backwards through time independently of the passage of time in the program itself". Something like that, anyway.
You might be right about such a verse, but I'm not sure off the top of my head. I can assure you though that you can find Christian proponents of both A-theory and B-theory of time. This is an active area of disagreement, particularly among philosophers (although it's true that a lot of question are under active disagreement among philosophers!). Example discussion, which I'm not up to date on myself: https://iep.utm.edu/god-time/
It is a popular notion that God exists outside of time but this is a modern idea with very sketchy biblical support. Certainly there is nothing in the Bible that directly says anything like this.
There are plenty of us of faith who like to overthink things. Amongst philosophers of religion, those who professionally spend a lot of time overthinking things, you'll find an abundance of theists. While many of the questions they consider are not scientific in nature (just like, for example, questions about mathematics are not typically scientific questions), beliefs should still be compatible with the known facts.
Good without evil is positive without negative, left without right, up without down, hot without cold. And like all those other pairs, good and evil are relative, as are happiness and misery.
It's for this reason that absolute avoidance of "sin" is misguided, even assuming we could reliably identify it. We were always meant to eat from the Tree of Knowledge; it was there for a reason, and the alternative would've been a rather stagnant and meaningless existence - certainly devoid of suffering, but also of joy.
> Good without evil is positive without negative, left without right, up without down, hot without cold. And like all those other pairs, good and evil are relative, as are happiness and misery.
This resonates with what I've read about the gnostic understanding of the creation. The demiurge (the God of this world) created this world to have a ratio of 2/3 light and 1/3 darkness. Suffering and conflict is produced to create tension and perpetuate the system.
To me that seems like an incomplete explanation that ignores the hard part of the problem it’s trying to satisfy.
It’s easy to explain the suffering that can happen during one’s life as part of a wider experience which ultimately ends up being good, when the examples are adults with a range of experience and agency over their situation.
It’s less easy to explain why a good god has created an existence where a young child who doesn’t yet have agency over their existence contracts and dies of smallpox. Or is brutally raped and murdered. Or…
I think overall the challenge of the problem of evil for LDS is different from that of the Christian tradition. Christians believe there is just one God who created the physical universe, and created the life within it (either directly or by setting up laws that would lead to the inevitable outcome of life), and in a very real sense foreordained all that suffering and pain knowing that it would come.
The LDS church, on the other hand, teaches that "As man now is, God once was; as God now is, man may be". I'm not familiar enough with LDS teaching, but if their god was once like us, then that means that this god did not create life, given that this god was a living thing before having the power to create life (and is this the same for that god's god? And the god of that god? And so on?). That suggests to me that this god is not the creator of physical reality (contrary to what Christians think), and not the original creator of life, and therefore is not as obviously responsible for a physical reality full of suffering as is God for Christians. The LDS god did not set up the original rules, and so can't be as responsible for them. That being said, the god of the LDS does seem to be very powerful, so that would give rise to some forms of the problem of evil.
These are just some poorly informed thoughts, and there's a lot I don't know about the LDS church.
When I was a believer, I always thought the best answer to this is that suffering is brief & temporary when considered against eternal paradise.
Looking deeper, suffering is also necessary to allow for the gift of immortality to be a choice, and to be 'fair'-- those who cannot resist the desire to cause misery for others must be given the chance to demonstrate for everyone else why they should not be granted immortality. If God just snuffed them out at the first sign of trouble everyone would start to wonder if God was really being just. [Oh, I also didn't believe in eternal hell, just a final judgment where the 'bad guys' are all destroyed so the rest of us can actually start enjoying life without any more misery.]
You will find thousands of other quite different responses to this question because it is the most common question asked about God.
I don't really believe any of that stuff any more, but the beliefs I described brought me comfort for a long time in a dark place and I still think they make more sense than any other irrational, unprovable belief system I've looked into.
Ha, you like to ask the hard ones, and I have to head out right now :) Short version: for every view of the world, there's things it explains well, and things that are a challenge for it. Some theistic views I think as a whole do a great job of providing a solid worldview. However, problems of evil -- why is there natural evil, moral evil, misery, etc -- these are one of the areas that are probably the biggest challenge for theists that believe in a good God. Needless to say, there's a massive amount of words written about this topic. The short answer is: there is no logical problem of evil -- one where this kind of thing is logically incompatible with the existence of God. i.e., there's no proof that shows that a good God cannot have a reason for allowing evil/suffering/misery/etc. But it still presents an emotional challenge, and it does seem like they're an uncomfortable pair, even if not logically incompatible.
I have my own views on how to explain this, but it would take a fair bit to explain.
OK, here's my amateur take. Most misery is man-made. On the personal scale: envy, unrequited love etc. Also on the macro scale: wars, global warming etc. Perhaps if you create entities with free will they will unavoidably though ignorance or malice do some evil to a lesser to greater extent and therefore cause misery.
Bereavement is unavoidable but many religions promise an afterlife.
Child bone cancer and like are difficult to explain away. Perhaps we would have a cure for cancer if we didn't spend so much effort developing weapons and better advertising algorithms, but that is besides the point. I have heard Muslims believe that Allah will not inflict suffering on someone beyond what they can handle.
God, if they exists, could have created world we everyone were in a state of continually bliss, but what would be a point of that?
> I have heard Muslims believe that Allah will not inflict suffering on someone beyond what they can handle.
I find this a particularly inhumane way of thinking. Try saying that to someone suffering "oh, you can handle it", it's beyond cruel, yikes. Makes it sound like it's some type of blessing, like the little 3-yr old is meant to die of bone cancer because of some greater God's plan. I don't know, it's just sounds so wrong to me to think like that. Even life on earth is some sort of school for the afterlife, I don't think there is a lesson to be learned by dying of cancer as a young child.
> God, if they exists, could have created world we everyone were in a state of continually bliss, but what would be a point of that?
Yes please, isn't that what heaven is supposed to be?
> God, if they exists, could have created world we everyone were in a state of continually bliss, but what would be a point of that?
What would be the point of not doing that?
It's not really about individual suffering -- god could have created a universe in which suffering did not exist as a possibility or a concept. But it does so exist. Therefore God either intended it to be so, and condones or accepts or requires suffering, or God has limits that mean it had no choice but to create the universe this way, or there is no God.
Yes, if God exists, is the creator, is all powerful, is good, is sane, then suffering must be of ultimate benefit, or an unavoidable consequence of for example free will. That said lot of suffering is man made.
> Perhaps if you create entities with free will they will unavoidably though ignorance or malice do some evil to a lesser to greater extent and therefore cause misery.
Well, to be sure, you have to nudge a bit and create such circumstances to make sure there will be misery and wars. For starters start several opposing religious factions, all willing to do god's bidding and do horrible things in his name. Don't discourage it, leave your words in ancient manuscripts open to interpretation.
"the original cloud" is the heaven universe I think, but please be sure to put on your tin foil hat, here some ideas that are a bit out there :)
> Our reality is a constantly changing bubble. Within that bubble, both our future histories, as well as our past histories (!) are subject to change. This bubble of reality is an environment, set up by soul, to create experiences by which the consciousness can be exposed to.
> “time” is just our consciousness moving in and out of different world-lines. Each world-line is our momentary reality. During that “in between period”, our consciousness is in “wave form”, and we are in what is commonly referred to as “Heaven”.
Not sure; it's not in my notes. I want to say an HN comment, but I don't recognize any of the few that include the link.
--
Edit: The browser history still exists, although I cannot disprove that it was created Last Thursday; 'twas the comment near the bottom of this thread that intrigued me with its sole content, that link: https://news.ycombinator.com/item?id=1755748
If you care about the question more than from a purely curiosity standpoint, there is a difference tween “flesh” and “body” in (at least some) of Christianity. The “Lord of Spirits” (an orthodox podcast) has done an in-depth discussion on both the body of God and the bodies of humans, angels and demons. Just as an example, when Adam and Eve was expelled from the garden they were covered in “garments of flesh/skin” depending on the translation.
I do not want to start a discussion on Christianity, just to point to that there is a more subtle understanding in the church whether or not you believe in it.
As one who has read the Protestant Bible all the way through probably more than five times, I don't recall any statement that memories will be wiped.
At the end of Revelation there is a declaration that ~"there will be no more crying, or tears, or death, or pain, for the former things have passed away," and some interpret that to mean humans will not remember anything from life in the old universe.
It's an interpretation, though, not something the text outright says.
During my life as a Biblical literalist, I saw it as simply saying that a world with hardship and suffering was no more, and that our memories of those times would be recontextualized.
JP Moreland has written at length on this topic (see his book "The Soul" and many interviews/talks he's done).
In short, he distinguishes between the brain and the mind (consciousness, memories, etc). While the brain may be required for an embodied creature to use their mind, they are not the same thing.
In short, he distinguishes between the heart and circulation (pulse, o2 transport, etc). While the heart may be required for an embodied creature to use their circulatory system, they are not the same thing.
If a bomb vaporized your brain you would cease to be an embodied creature and you wouldn't have a mind anymore. You can test this theory yourself but only once.
> If a bomb vaporized your brain you would cease to be an embodied creature and you wouldn't have a mind anymore. You can test this theory yourself but only once.
You actually can't test this theory at all, if it's correct.
On destruction of your body, if the mind does not continue, you cannot observe its discontinuance. Thus, you cannot test the theory.
If the theory is false, then you could presumably falsify it by this technique.
[O'Brien to Winston Smith]: 'Is it your opinion, Winston, that the past has real existence?'
Again the feeling of helplessness descended upon Winston. His eyes flitted towards the dial. He not only did not know whether 'yes' or 'no' was the answer that would save him from pain; he did not even know which answer he believed to be the true one.
O'Brien smiled faintly. 'You are no metaphysician, Winston,' he said. 'Until this moment you had never considered what is meant by existence. I will put it more precisely. Does the past exist concretely, in space? Is there somewhere or other a place, a world of solid objects, where the past is still happening?'
'No.'
'Then where does the past exist, if at all?'
'In records. It is written down.'
'In records. And- ?'
'In the mind. In human memories.
'In memory. Very well, then. We, the Party, control all records, and we control all memories. Then we control the past, do we not?'
https://www.abhafoundation.org/assets/books/html/1984/162.ht...