Gödel and the unreality of time | Hacker News Reader

Gödel and the unreality of time

edwardfeser.blogspot.com

196 pointschesterfield129 comments

I once saw a fridge magnet that said "time is natures way of making sure everything doesn't happen all at once," and it's stuck with me.

The concept of time not being "real," can be useful as an exercise for modelling problems where to fully explore the problem space, you need to decouple your solutions from needing them to occur in an order or sequence.

From an engineering perspective, "removing" time means you can model problems abstractly by stepping back from a problem and asking, what are all possible states of the mechanism, then which ones are we implementing, and finally, in what order. This is different from the relatively stochastic approach most people take of "given X, what is the necessary next step to get to desired endstate."

More simply, as a tool, time helps us apprehend the states of a system by reducing the scope of our perception of them to sets of serial, ordered phenomena.

Whether it is "real," or an artifact of our perception is sort of immaterial when you can choose to reason about things with it, or without it. A friend once joked that math is what you get when you remove time from physics.

I look forward to the author's new book.

If I remember correctly, the full form of that joke is that time is nature's way of preventing everything from happening at once and space is nature's way of preventing everything from happening in Cambridge.

That may be a variant.

https://en.wikiquote.org/wiki/John_Archibald_Wheeler

cites some old sources that are (probably) a few years older than the Cambridge version:

http://www.ggdc.net/maddison/Personal/Autobiog1994.pdf

says:

> As Dharma Kumar paraphrased Joan Robinson, "time is a device to prevent everything happening at once, space is a device to prevent it all happening in Cambridge".

What does the idea of time not being real have to do with thinking about a system across different points in times in its evolution?

The idea of time being real or not raises the question of whether it's, a) always necessary to consider, and b) whether viewing a problem in the scope of a time domain always necessarily adds more information than it removes from scope.

It's just interesting to consider whether assuming time as a necessary variable can create an artificial constraint on reasoning.

The specific example I was thinking of is in an ontology, where you have all these types of information, related in different ways, that are all factors in each others behavior, but you can't model the whole thing as a function or transaction. That is, adding time (a transaction order) reduces the scope of what you can include in your model.

From a writerly laymans perspective, asking whether time is a real and universal property of all systems or an artifact of how we interpret them, is analogous to imagining we were studying physics with a heuristically useful, but generally limiting presupposition. One which would be like presuming all algorithms were in P, all graphs had hamiltonian cycles, all consistent theorems were true, etc. Then considering the consequences of the alternative.

It's all very meta and fun to think about, but I suppose that's what this topic is about.

> The idea of time being real or not raises the question of whether it's, a) always necessary to consider...

Not really. Time could be real, and still not necessary to consider in all situations.

I think this argument applies to your b) as well, but I'm less sure of that...

So to clarify, we can choose to use time whether it's real or not.

The question is, given it isn't always applicable, and it may not always be necessary where it is partially so, are there situations where it causes paradoxes where it is a source of noise instead of information, and how can we know when applying it whether it causes one or the other?

Godel as a logician would have approached it as just another formalism.

If reconciling models of physical phenomena with models of time produces inconsistency and paradoxes, he'd ask whether we were first sure that was time intrinsic to those physical phenomena, or does our model of time impose an arbitrary constraint on our ability to reason more abstractly about them.

My point is that it's a reasonable question with related applications. Not sure there is a wrong to be here.

> Not sure there is a wrong to be here.

"Not even wrong" isn't a mark in favor of a model...

I think your explanation is quite good. Assuming I understood you correctly, a shallow example might be a basic electronic circuit - a bulb, battery and switch connected in series. You could model the whole circuit without any concept of time even though the flow of electricity is not instantaneous.

Folks are asking about the practical import of time not passing---if indeed it does not. I know of this rather substantial one: my fear of death, and I guess that of other people too, depends on the notion that my own annihilation in time, and that of everything I care about, is absolute and definitive. Existence no longer has me as one of its inhabitants, and that's that.

This picture is in its turn grounded on a presentist theory of time (the idea that only the present exists), or at least an A-theory of time (the idea that the present is somehow special, in absolute terms.) Nothing like that is true if time does not pass: all of the moments that make me and everything I care about are still there, occupying their own spacetime regions, eternal, in a way.

Realizing this has helped me see death from a slightly different perspective. It still sucks, but it no longer feels like the absolutely unaceptable deal I used to think it was.

While I can see that that's comforting, perhpas in the same way as believing that all your deceased loved ones are in heaven, does it really make a difference if we can't perceive those other 'there's?

Well, supposing that heaven doesn't exist, it's very different at least in that they really are in those other, fully existing times.

Re: your suggestion that whatever cannot be perceived does not make a difference to us, I care deeply about the future wellbeing of my family, including those years I won't see because I'll be long dead. I'd bet you do too.

You seem to miss the point with every response to your original comment. You keep saying things about the importance of things that can't be perceived. No one is suggesting that things don't "make a difference to us" if they aren't perceived. That's silly and doesn't even make sense - of course we care about certain things that we don't (or won't) perceive.

The point is that we experience time as flowing in a certain direction and can't experience it any other way. Knowing that we continue to exist in some tiny sliver of spacetime doesn't change that fact, and so it is not very comforting, for easily understandable reasons.

If you're on your deathbed, with your conscious experience about to flicker and die, no one in the room is going to be comforted by you saying "well look at it this way, my 2 year old self still exists somewhere that you can't ever access and that I'll never return to, and even if I did, none of us would have any idea that this conversation was going to happen in 90 years".

If time is not a straight progression where the past is what happened and the now is reality and the future is what might happen, that's interesting and changes a lot about how we model things.

But as long as you can only perceive it as such, it's a meaningless distinction from a practical view.

Hm, I would have expected more respect to the importance of the unperceived from a reificator.

Fair enough, I can't argue with that.

But outside of something like serializing events in an application, I don't think I can reify time. If you've got an idea for it, please clue me in because the possibilities are endless.

How do you decide that your new view is valid and is not based on your need to lessen the fear of death. I have problems with this with every new thing I try to use to make death more palatable, be it religion, philosophy or anything else. I just cannot believe in anything because I feel its just a convenient way to make the fear smaller. How can any view be valid if its based on self interest?

I find it weirdly comforting to know that nothing in this universe is really eternal. If you could live literally forever, you'd witness the end of all life on earth in about a billion years, and eventually the slow heat death of the universe.

I'd love a lot more life than I have in front of me - a few millenia at least - but even with a traditional, linear view of time there's no point, need or possibility of eternity.

Even if the universe were eternal, the way I see it eternity is just another kind of ending. I think the important thing to realize is that a thing does not cease to have value simply because it is impermanent.

It will cease to have value when there's nobody left to value it.

Why? Can't we value things that will exist in a future where we no longer belong?

We can value whatever, but eventually there won't be anyone left to do the valuing. Impermanence doesn't stop us from valuing, but impermanence does guarantee that value won't last. Which may or may not bother us now, depending on how existentially grumpy we feel in the moment. But luckily, those feelings are impermanent as well.

All true, but of course the point of the idea we're discussing here is that there may not be any reason to assign special weight to the value of things in the present or the future, over the value of things in the past.

It can value itself. After all, that's what it's doing now via us. It doesn't necessarily have to configure itself into something like a human to perceive and appreciate itself.

What is "it" when "it" is purely random noise? By definition and known physics, heat-death of the universe means there is absolutely no configuration.

Is the noise truly random, or is it just unpredictable? Does the maximization of entropy indicate no deviations from equilibrium will spontaneously occur? Does the lack of memory indicate a lack of consciousness?

In this case the view in question (the B-theory of time) is supposed to be backed up by science: e.g., the Gödelian models in the OP, but, much more than that, the relativity of simultaneity. The RoS is really non-negotiable, and still entails that the actual world does not have a Newtonian absolute present.

While the RoS indicates that observers won't agree on the order of distant events, I don't think that it eliminates the possibility of an absolute present moment. You could simulate a system with relativistic physics just fine with a single global clock, just by adjusting the local simulation refresh rate to account for time dilation. Players might disagree on the order of events and the amount of time that had passed, but they would still update based on the progress of the global simulation clock, modulo the local refresh rate.

What is the benefit of the global clock, in that case?

It gives you a single "correct" order of events, and a single present state.

It gives to whom a single correct order of events and present state? Not to me. Only to "God", an entity external to the system.

Which is fine if you are a God (or programmer) building a simulation, but has no objective meaning to anyone inside.

Right, that's interesting. Thanks. This is analogous to saying that we live in an Einsteinian simulation run from a Newtonian world, right?

I prefer to imagine we exist in a roughly newtonian program, but the computer executing it is a distributed system with finite local resources, so it doesn't all run in sync.

Do you know of anywhere where a model representing this is construed explicitly? It seems like the kind of thing that is harder than it seems, if you know what I mean :)

What's wrong with self interest? That's a serious question.

I don't mean that in a nihilistic, nothing is true, everything is permissible way. Nor do I mean it's ok to arbitrarily pick fantasies to believe, especially if that leads us to imposing the consequences of those beliefs on other people. There are few beneficial delusions. The question is, what do you care about in life and what are your goals.

How you choose to think about things is a tool you can use to help you on a productive path. If a certain way of thinking helps you maintain an even keel mentally, then that can be useful. It doesn't take blind faith, you don't have to exclude the possibility of alternate explanations, keeping an open mind is fine, but if this is a plausible possibility then why not take some comfort from that? It doesn't necessarily mean you're compromising any of your principles to do so.

I find this to be an eminently reasonable perspective, which did not deserve to be downvoted.

Existential anxiety can be extremely debilitating. If one plausible interpretation of time brings you comfort, there's no harm in focusing on it.

Well, "appeal to consequences of belief" is a logical fallacy. But yes, of course it's possible that inaccurate views of the world can actually bring about better outcomes than accurate ones

> all of the moments that make me and everything I care about are still there, occupying their own spacetime regions, eternal, in a way.

Yes but not evolving anymore. What sucks isn't really not existing anymore, what do sucks is having no future. If a supervillain's evil plan was eternally freezing the universe right now, I would be as sad as if it was making it disappear.

The block universe doesn't mean a specific moment in time is all that is, it means that they all coexist.

Dynamics in block universe is like reading a book: it seems things happen as you move your attention over the pages, but in truth the story was fixed before you even started.

Which is fine but it's not a meaningful change to the perspective of me on page 120 when I think "when we reach page 163 I will no longer feature in this novel".

Our problems with death are, basically, ego. How you mentally model time and the universe doesn't take that away

While I agree that death will feature no matter how you model time, the difference between the flowing time and the block universe in this regard is that in the block universe you never cease to exist.

In the model of flowing time, once you are dead you've passed out of existence, only to be clinging on trough the memories of others.

M. Williams wrote a well-regarded treatise on this topic:

https://www.amazon.com/We-Are-Book-Elephant-Piggie/dp/142313...

> what do sucks is having no future

Nature has a clever way of dealing with this: at a certain point in life you begin wishing you had no future.

There's a better way to look at your mortality, I think, which is to realize that your conception of self is flawed. Try this as an exercise: determine precisely which part of you is "you", the part that if it were to change or cease to exist would make you a different person. What you'll find is that there isn't one. Every part of what you are has changed and evolved over time. Then ask yourself why it is that people are often willing to die for their family, community, nation, or even ideology.

There's one conception of self that I consider fairly constant, my ability to consciously perceive what's going on around me. Despite the fact that all of my body's cells get replaced completely every 7 years, _the fact that I perceive the world from "my" perspective remains constant_

Apart from that, I don't believe in a self.

I assume, that when I die, this perspective goes away as well, I consider death to equal a total loss of consciousness ability to percieve.

> _the fact that I perceive the world from "my" perspective remains constant_

That's only your perception because you have memory. If we copied your memories right now and put them in a robot body 3000 years from now, it would also have the illusion of a single continuous perspective.

And that robot would be me.

What if we put "me" into 2 robots? What if one robot "killed" the other "me"?

How do you know it was the same consciousness doing the perceiving, though? You think because you can remember things that you were also the one that perceived them, but you can take a hard drive and move it from one computer to another and the data is still accessible. It is likely there is no part of you that is fixed, even your consciousness.

On the plus side, much like matter and energy, it is unlikely that consciousness is created or destroyed in the operations of the universe. Instead, it just gets reconfigured.

Have you really been continually conscious throughout that time though?

Recent thinking about this in neurology is that we are not. We're not concious most of the time we are asleep, and in fact are unaware of our own thoughts much of the time we are awake. Arguably when we are 'lost in the moment' or acting on instinct or training there's really not much conscious cognition going on because frankly it just gets in the way. It seems likely that conscious thought is something we only do as and when we need or want to, but we spend much of our time in an 'animal' state.

Have you ever been reading a book and someone had to poke you to make you aware of them? The auditory processing parts of your brain were simply not functioning. We switch on and off different faculties of the brain all the time, and immediate conscious awareness of the present is just another one of those.

> I assume, that when I die, this perspective goes away as well, I consider death to equal a total loss of consciousness ability to percieve.

The perspective goes away, but the ability to perceive is not part of the perspective. An old telescope goes offline, but the scientist is still there, peering through other telescopes. The body dies, but that which experiences the world through it doesn't.

This is from "the perennial philsophy" (cf. Aldous Huxley), if you want to look into it, though a bit esoteric and not easy to find a contemporary simple explanation of it.

Has your perspective ever changed?

Have you ever had amnesia (loss of memory), or creation of false memory, via disease, injury, inebriation, or anesthesia? 99.99% likely you have.

It definitely has, I wanted to include the word "permanent" in my definition, but thought it'd be a bit much. I've experienced blackouts, extremely deep sleep (where you go to sleep and feel like you wake up a second later, even though 8 hours have passed) and driving on autopilot, where your consciousness just goes away completely, and you find yourself 10 minutes closer to your destination, as if you've teleported.

I'm not saying my conscious perception is constant, but if you plot consciousness as a binary variable on a graph (conscious, not conscious), a lifetime would look something like this, relatively constant.

    Before birth               Birth                 ..... life ......                 death
    .............................~~--------------------------------------.------------------................

    . = not conscious
    ~ = ..?
    - = conscious

And I'd argue that during dreams you're conscious too, you just forget about it, this claim is supported by contemporary research on sleep and dreaming for as far as my pop-psychology knowledge goes.

That's disproof of a binary notion of self. It doesn't disprove a statistical notion of self, which is a stronger sense of self than a purely uniform universal non-self existence.

“but it no longer feels like the absolutely unaceptable deal I used to think it was.” May I suggest this feeling has more to do with biochemistry than the philosophy? :-) In the sense that this can do with the hormonal level and the anxiety or anger that are controlled by it.

I think you are right. The philosophy is just in realizing the relevance of certain theories in physics to how death should be conceived. But then, yeah, psychology takes over :)

Whether all moments of time exist in a hypothetical fashion or not, only one now exists to me subjectively - or at least so my memory of my subjectivity claims.

Further, memory itself gives the impression of irreversible time.

Entropy gives the impression of irreversible time, as well.

"I do not fear death. I had been dead for billions and billions of years before I was born, and had not suffered the slightest inconvenience from it." -- Mark Twain

Cute, but I think there is a substantial difference between not born and dead.

I don't know why you think that. I think the safest assumption is that being dead will be exactly like not being born.

one state is indefinite and the other is not.

It's like saying that the future is exactly like the past. (Which is true when applied to the question of non-existence, because what did not exist will cease to exist or continue to be non-existent.)

But that is only true of things which do not come into existence, no? I can safely say I did not exist a thousand years ago, nor will I exist in a thousand years. Further, I can say that from my point of death on, I am non-existent. Similarly, before my birth, I was non-existent.

However, my state of non-existence ended at my birth. Just as my state of existence will end at my death.

In this regard, the future is not exactly like the past. In the past, there was never a time in which I came into existence. In the future, there was a time where I came into existence. Neither of those statements transfer between past and future.

> In the future, there was a time

This is "memory", or "trace". Their existence take away from your non-existence, making it incomplete (imperfect), which indeed makes one's future different from one's past.

>I can safely say I did not exist a thousand years ago...

I'm not sure of that, yet. We haven't managed to pin down what "I" is or even what "existence" is. I'm thinking in the "we virtualized a copy of your brain" sense - just what is consciousness?

> what "existence" is

Indeed, the very existence (and non-existence) could be relative - just like time and space. For example, in one frame of reference there may exist a magnetic field while in the other there may be none.

Being dead, like not being born, are both not being at all.

> I think the safest assumption is that being dead will be exactly like not being born.

From a purely entropic and information theoretic standpoint, these are very different states and certainly not a safe assumption.

In this Philosophia Non Existentiae you also have to make a distinction between "not born (yet)" and "not born (ever)".

Isn't that implicit, though? By virtue of being able to state that at some point you were not born, you were necessarily at some point born.

Non-existence is complicated. In an obvious (and trivial) sense future itself does not exist, so one cannot tell whether someone in particular (e.g. another Einstein) is not born "yet" or "ever".

On the other hand, one might argue that (for example) wasted sperm and eggs should count as "not born". But even that can be seen as too limiting, because - perhaps, somewhat paradoxically - to be completely objective one should be considering statistical parameters rather than a physical measure.

First, I'll agree that my not existing after death would be similar to my not existing before death. In that, it helps make this a cute saying.

However, that still says nothing of the difference between dying and not being born. Just because things have a large similarity does not mean they are equal, after all.

Your odd argument that "wasted" sperm and such should somehow count towards "born/not born" just seems a non-sequitor. That is quite literally unrelated. The sperm/egg are merely mechanisms and say nothing of the person unless we plan on presupposing a conscious person exists before they exist.

Well, clearly, non-existence after death is different from both types of non-existence mentioned above. (Incidentally, there are many more types of non-existence than just these.)

Isn't that inline with what I was saying?

> Non-existence is complicated.

Doesn't look like anything to me.

It does exist, though.

Re sperm and eggs, this is my go-to argument against anti-womans-choicers: functionally there is no difference between plan A (condoms and birth control), plan B (the morning after pill), and plan C (abortion) - all three result in a baby not being born. If one is going to argue that it's a crime that a fertilized egg is terminated, one must also lament the loss of billions of lives to periods.

Unfortunately this argument doesn't hold water when someone tries to say that their god intervenes and decides to overcome man-made barriers to fertilization, because that particular special snowflake baby needs to be born. Unsure why the soul assigned to that fertilized egg doesn't just find another but that just goes to show how messy the whole damn debate is.

Incidentally, this is also my argument against me having babies - knowing that regardless of the number of babies I have, I will feel unconditional love and gratitude at each and every one's existence, and because I can't possibly compare my comfort or economic well being against the value of a human life, the only logical conclusion I can come to is I should have as many babies as I physically can. Or, I should have none.

> I should have as many babies as I physically can

Consider quantity vs. quality, though. Quoting Lenin, "We must follow the rule: Better fewer, but better. We must follow the rule: Better get good human material in two or even three years than work in haste without hope of getting any at all." 'None' would be the best choice here: you could, instead, adopt a child and by doing so save a life and contribute to keeping the human population within reasonable bounds at the same time!

> Unsure why the soul assigned to that fertilized egg doesn't just find another

That's the thing with free will - if it's free, then it can choose things that will prevent (for example) the woman who will discover a general cure for cancer from being born. Just as a random guy with a knife can prevent that same woman from publishing the cure she figured out last night when he stabs her to death in an alley in Queens. "Free will without consequences" is as nonsensical as "rights without duties".

What is that difference exactly?

Do you need it exactly, to know that it exists? What is the difference between two stars in the sky? Must you know the physical differences exactly to say they are different?

What is the "substantial difference"?

Again, why would I have to be explicit/exact on it? Two stars in the sky have an obvious substantial difference between their existences. Even if I couldn't readily express what those differences are.

I mean, I get that these are fun discussions to have. Likely even meaningful. But the odd friction this is adding to enter the conversation seems overblown.

>Again, why would I have to be explicit/exact on it

Did I ask you to be "explicit/exact"? I'm just curious for you to describe, at all, the supposed "substantial difference" that you apparently know of between being "not yet born" and being "dead".

>Two stars in the sky have an obvious substantial difference between their existences.

In what way are two stars analogous at all to being not yet born and being dead?

There are links to Epicurean and Taoist philosophy.

Here's a different take, another thought experiment Re: death, from Sigmund Freud, Reflections on War and Death:

“We cannot, indeed, imagine our own death; whenever we try to do so we find that we survive ourselves as spectators. The school of psychoanalysis could thus assert that at bottom no one believes in his own death, which amounts to saying: in the unconscious every one of us is convinced of his immortality.”

[Edit: Frued->Freud]

I think this is an important consideration. A subjective observer can never be ‘dead’ from their own perspective. So we are left with something like Zeno’s paradox. We can get closer and closer and closer to death, but we will never reach the end. Could this lead to a form of eternal life? Your final living moment, subdivided endlessly, could play out as entire additional lifetimes in your experience.

>A subjective observer can never be ‘dead’ from their own perspective.

As a former boxer who has been "knocked out", I have always speculated that feeling is akin to what death would "feel like" (that is, nothing at all). When you are knocked out (as aside from asleep) you have no experience. You don't dream, you don't feel has though time has passed - you don't feel anything. One second you are awake and aware and the next second you wake up lying on the ground (or don't wake up at all, if you are dead). It feels like an instant, no matter how long you actually been knocked out for. This makes it different than sleeping and simply not remembering your dreams upon waking.

This may not be everyone's experience, but I have been "lucky" enough to be choked out accidentally during some sparring sessions.

It doesn't always happen this way, but when it does it's insightful: I first get a very strong sense of "Wrong," as my understanding of the laws of physics vanish. If the choke has finished and I'm left standing but still going to black out, I'll probably topple at this point as I misunderstand gravity and forget about/lose control of my legs.

Enough of my ego will still be aware enough to have the thought "this is embarrassing, I've fallen," but it fades quickly as I lose understanding of why falling is bad, what embarrassment is, and what ground is. Then there will be a fading out of visual input (auditory goes before anything else), with my awareness quickly shrinking to a tiny ball of awareness, which visualizes itself as a bright speck of light surrounded by nothing. Panic will still exist and set in, as the speck loses subsystem after subsystem, not quite sure what is being lost but knowing things are, and feeling an encroaching blackness.

Eventually the only thing left is a feeble desire to not vanish, followed by nothing.

This might actually happen every time I get choked out, but only the right circumstances allow it to be "written" to memory.

It aligns with what friends have told me about near death experiences (heart attacks, overdose).

I wonder how much this aligns with the parts of the physical brain associated with those different parts of the consciousness (ego, understanding, fear, sensory, autonomous nervous system), and when they start to be deprived of oxygen. From the way you described it, it very much has the feel of going back in time from "civilized person" to "lizard brain".

Very similar to the way death is described in Lucretius' de natura rerum.

Just as it takes infinite local time to enter a Black Hole, we live for the entirety of our lives. We are immortal, for in our local frame of reference, we will never die, just as a mathematical point existing in the open interval (0,1) will never reach the end of the interval.

That is Schopenhauer's argument against fear of death. Not that it was unique to him, but since Twain was writing during Schopenhauer's popularity, I wonder if he found it there.

You should fear the absence of death, if people never died, the earth would be a pretty crowded place. (The dead greatly outnumber the living, with estimates ranging from 50-108 billion).

To go further, if nothing living ever died, the whole biosphere couldn't work at all.

Life exists because of death. Saying we like life, but not death, is like saying: "I love breathing in, but I hate breathing out."

You can just as easily have a Newtonian space with time travel (roll up the time coordinate in a circle by identifying T=0 with T=1). I think the same trivial construction would work in GR, so you don't need mass, rotation, etc. That doesn't seem to prove anything about the nature of time. Does anyone have a copy of Gödel's article so we can see if the argument goes deeper?

Of course it's must deeper than that.

http://kurtgoedel.de/cms-83FO/wp-content/uploads/2016/10/Goe...

It's a solution allowed by GTR, not a new trick definition. It belongs to the family of 'dust solutions'. You arrange particles (can be as big as galaxies) that move in certain way and you get time travel. Only other assumption is nonzero cosmological constant.

You can't get time travel in Newtonian universe just by arranging objects in it to move certain way.

In general, closed timelike curves are allowed in GTR. It's possible generate them several different ways. Gödel just made super elegant one. What GTR allows and what actually is allowed are different matters. Just like Newtons equations break at some extremes, same probably happens to GTR.

I see. Thanks for the link!

If two trains are heading toward each other on the same track, one way for momentum to be conserved is if they pass through each other. Even though that's not what we observe in the real universe, its existence as a mathematical solution implies that mass is an illusion. How is this argument different from Godel's?

For those interested in the topic, I can't help but reccomend the book Gödel, Escher, Bach: An Eternal Golden Braid by Douglas Hofstadter.

Seconded. There's a whole MIT course on it: https://www.youtube.com/watch?v=lWZ2Bz0tS-s

I’m fairly certain that this isn’t covered at all in that book.

You are correct, it is not, and the book is not relevant in any way to the article, aside from both containing references to the work of Gödel.

Presumably it would take you five years to figure that out though, by which point you may have discovered new interests.

Not directly, but it is closely related. It still is likely to interest most who were interested by this article

I liked that book but remembered it being more about incompleteness theorem and cognition than time / space physics.

For French speaking folks, listen to this course by Bouveresse https://www.youtube.com/watch?v=0kCfgM0U3kw&list=PLOq4PLensL...

"Time is an illusion. Lunchtime doubly so" - Douglas Adams

First thing that came to mind when I read the title. Ctrl+F "lunch". You beat me to it.

For those curious, the paper (or at least a paper) on the subject:

http://dx.doi.org/10.1103/RevModPhys.21.447

got reminded of the book "Siddhartha" by hermann hesse

"After listening to the river, Siddhartha’s biggest insight is that time is an illusion and that life is not a continuum of events, but instead is omnipresent. Eternity springs from the world’s unity. Understanding the past and the future as part of the present is a major component of achieving enlightenment."

OK, so tldr: If you can't define a partial ordering between events (ie. "earlier than" as in A can cause B, "later than" as in A can be caused by B, "same time" as in there can be no causal relationship between A and B), then time as defined in B-theory can't exist.

So what? What are the consequences?

Nothing! It's fun thinking about it.

I think, he's trying to say that "time" is really not a thing, but rather our perception and understanding of time makes it a thing. What we should see as time is actually some flow of causality. You cannot map "earlier/later than" or "same time" to causal reality, those qualities only refer to time as a scale, not as a natural occurrence of causality order. Or so I think.

In other words, time emerges from causality (and our observation of it), not the other way around. Is that right?

From the article, "[this] casts doubt on the reality of time in our world".

If the order is undefined, then how can you say I'm late?

The order between (1) "you being late" and (2) "you departing home at 09:05" is undetermined, but the events themselves aren't.

Or: it doesn't matter in which order you write the events of a story, as long as the events themselves are in order. The author is not bound by the timeline of the story.

If there is no way to define an unambiguous time ordering, then you cannot use a "flow" of time picture to describe time. In other words, despite the everyday perception of time as something that marches ever onward, in reality we live in a "block" universe where nothing moves.

Or so was supposedly Gödel's argument.

Also, our own perception of time depends on this "block universe where nothing moves" changing and enabling some synapses and chemical reactions in our brains. Hence, a change in this block could take an "eternity" (of real time, if there were such a thing) and we would only notice it as an infinitesimal moment.

Left as an exercise for the reader.

For example how this would correlate with the quantum entanglement, where the supposed spooky action is described as instantaneus, so this has no time to factor in. Not quite able to determine, which particle was actually seen/observed first so that you can have a causality flow.

There are some cool "practical" consequences like building time machines. But you need some serious civil engineering equipment: First take a mass the size of a star. Squeeze it into a thin really really long cylinder, make it rotate very fast ... and boom! You can travel back to the day you created it.

[0] http://adsabs.harvard.edu/abs/1976PhDT........61T [1] https://en.wikipedia.org/wiki/Tipler_cylinder

Sipping espresso

Pause, muse on time's illusion

Work must resume, shame

You sell illusory time for illusory money in the simulation, so espresso is illusory too, I'm afraid.

You haven't shown that "Illusion" is transitive

Nothing is real in the simulation, I believe.

That's a different point than the one you were making!

And I didn't mean illusory in opposition to real. Is the pleasure I derive from an illusory steak in the Matrix not real?

The pleasure is in fact real and cannot be made illusory.

Off-topic but, was that supposed to be a haiku? I only count six syllables in the second line.

oops fixed

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