Carlo Rovelli’s radical perspective on reality | Hacker News Reader

Carlo Rovelli’s radical perspective on reality

quantamagazine.org

122 pointsvismit2000167 comments

I have a degree in theoretical physics and a gold medal, which is to say I have endured the requisite intellectual beatings. Often the best interpretations of physical theory are unpalatable to the average person. The idea that there is in fact no objective physical reality is the most egregious offender in this regard. However, it is nonetheless the best conclusion that one can draw given strict adherence to what the mathematical formalism of QM provides. There is simply no physical machinery to support an objective reality, period.

Now, that being said, the remarkable part is that the forgoing conclusion does us zero harm. We can still have the logical predictive fiction that an objective reality exists. What staggers the mind is the corollary that no human has ever erected a truth. Moreover, every intelligent species that ever endeavors to ask these questions will find the same non-answer.

>>no objective physical reality is…the best conclusion that one can draw given strict adherence to what the mathematical formalism of QM provides…

Can’t get on board with that. Relational QM/no objective reality is just one viewpoint, and it’s worth noting it’s not consensus.

To clarify he’s not claiming objects don’t exist, just that they don’t have observer independent properties.

It is fun to try and wrap your head around what no objective reality would mean. To grasp what we already have shown to be true about time being relative, the examples around simultaneity are a great wtf demonstration: https://en.wikipedia.org/wiki/Relativity_of_simultaneity

To clarify he’s not claiming objects don’t exist, just that they don’t have observer independent properties. -- that's right!

Isn’t it as likely that we have formulaic illusions like time that suffuse our inability to reach objectivity? And in those paradoxes: change only at Planck speed, motion is illusory, quantum gravity obeys probability as in Darwin, the theoretical observer independent reality exists.

The process of philosophy involves shedding illusions like words, statements, time, space to reach objectivity. A loop quantum gravity philosopher claiming there is no objective reality could just be an observer stuck at a bottleneck (notice he doesn’t call into question illusory attributes the piece relies on like biographical info).

Barbour’s observation, that quantum appears to demand specialization and record keeping at very unique planes (records are geology, fossils, impressions, photographs) hints that observers are what physical reality is, is counterpoint to “there is no objective reality.”

If reality is non trivially about record keeping, then of course there’s an objective reality, the Darwinian outcome is the objective sum of record keeping and the study of their differences.

Is existence an observer independent property?

no, unruh effect

You could say the same about relative existence of the magnetic field in classical electrodynamics.

Can you be more precise about what you mean by "objective reality"?

I would say that QM shows the world is not classical, but it doesn't say there's no objective reality: the predictions it makes about what we observe (reality) are extremely reliable and accurate (i.e. objective).

Yes, those predictions are just probabilistic for any single system, but when you have a lot of systems the probability that you will observe a specific outcome (to within observational error) can approach 1. A lot of our technology, such as lasers, transistors, etc., relies on this. I don't see how you make sense of that while denying there's objective reality.

Amateur here, certainly. But I recall that one of the two consequences of Bell's inequality (shown to be valid AFAIK) is that there isn't an "objective reality". Kind of like nature makes it up depending on what the observer is up to. Yes? No? Maybe?

Not really, no, but I can see why you might think that, because Bell's theorem is often described as saying that quantum mechanics contradicts "local realism", but "realism" in this sense has a precise technical meaning, which is that a physical system at some time has a complete set of well-defined values for all the possible measurements that we might do on it (and "local" just means that physical effects can't propagate faster than the speed of light). It was known since the beginning that quantum mechanics, as a theory, doesn't have this feature because of complementary observables, aka the uncertainty principle, which says that the more precisely some quantities are known, the less precisely the theory determines other quantities, e.g. in the case of a spin-1/2 particle, knowing the value of its spin along one axis means that it's value along any axis at right-angles is completely uncertain - it can be up or down with equal probability.

Nevertheless, it was thought (e.g. in the Einstein Podolsky Rosen paper in 1935) that it might be possible to formulate a theory that could reproduce all the correct predictions of quantum mechanics, while also ascribing simultaneous well-defined values to all the physical quantities possessed by a quantum system, i.e a locally realistic theory. These are also known as local "hidden variable" theories, where the idea was that some of the values of the variables might be unobserved simply because of measurement practicalities - we can't measure the spin of a particle along two orthogonal axes simultaneously because the measurement needs a magnetic field gradient along the direction we're measuring in.

Bell derived an inequality that any locally realistic theory must satisfy, and showed that quantum mechanics in fact violates this inequality, so no locally realistic theory can reproduce the predictions of quantum mechanics. Alain Aspect and others later implemented Bell's thought experiment in the lab and showed that the physical world obeys quantum mechanics, and so is not describable by a locally realistic theory.

In my view, none of that shows that there is "no objective reality". Rather, it shows that objective reality is as far as we can tell quantum mechanical, and not locally realistic in the sense described above. It's certainly the case that quantum mechanics requires a modification of the classical concepts of reality, i.e. of classical ideas about what a physical system is, but you would only accept that conclusion if you agree that quantum mechanics is telling you something objective about reality... At least according to how I understand those words.

So I think what people really mean when they say quantum mechanics shows there's no objective reality is just that it contradicts classical conceptions of physical systems, which is clearly true but sounds less sexy and mysterious.

In EPR, the setup is that there are two labs doing measurements outside of each other's lights cone. The outcome in one lab allows a perfect prediction of what happens in the other. This means that it is not possible that something random is going on in unless there is some nonlocal coordination between the two. This suggests that there is some actual fact of the matter as to how the experiment will turn out. That is, they argued that QM+locality = extra information beyond the wave function to determine outcomes. Bell then saw Bohm's theory and wondered about getting rid of the nonlocality. Bell showed that QM+extra info determining outcomes = nonlocal. In short, EPR + Bell shows that if QM predictions are correct (the predictions, not the theory), then there is something nonlocal going on. The lab experiments confirmed this and nature is indeed nonlocal.

Thus, there is no local theory that has definite experimental results compatible with what is actually demonstrated in labs. Many worlds, to the extent that one can apply any notion of locality to it, avoids this by not having singular, definitive experimental results (all results happen).

> The outcome in one lab allows a perfect prediction of what happens in the other.

I guess you know this, but just to clarify, that's only if the same measurement is performed in the other lab. If the other lab measures an orthogonal spin component, that result can't be predicted at all (I'm assuming entangled spin-1/2 particles for simplicity). It's more precise to say that measurement in the first lab tells you the state in the second lab, and with that information the probabilities for the various possible measurement results in the other lab can be predicted. In particular, if the other lab measures the spin along the same axis, the results can be perfectly correlated, as you say.

So there's some kind of nonlocality, but it's not the kind of nonlocality that makes problems with relativity, because the correlations can't be used to signal or cause any difference in the distant lab, only to predict, in general probabilistically, what would happen in the other lab if some measurements are performed. So entanglement allows this interesting middle ground between a local theory and a theory that's nonlocal in the sense that it would allow nonlocal causation, which is the kind of nonlocality that would worry Einstein. There should be different words for the different kinds of nonlocality, but maybe nonlocal correlation versus nonlocal causation serves the purpose

In EPR, it is critical that it is the same measurement. Bell explores doing different measurements. For EPR, they assumed that if you can predict with certainty what happens in a space-like separated region, then there must be a fact of the matter about it. Not being probabilistic was very important for that. Bell then showed that there cannot be a fact of the matter without there also being some nonlocal means going on in order to account for the QM predictions. It is critical to appreciate the two separate pieces of arguments, how they differ, and how jointly they do lead to some kind of nonlocality. Tim Maudlin has a, now old, book exploring these different levels of nonlocality in quantum mechanics.

I recently heard a talk from Tim Maudlin where he mentioned that foliations are the easiest and most natural structures to use to provide nonlocality and, if there is such a thing, maybe there is a clever way of using it to actually communicate and discover the foliation in some sense. He mentioned there is current research on using arrival times which are experimental results outside of the operator formalism, as far as I know. I found an article describing the research:

https://www.altpropulsion.com/ftl-quantum-communication-reth...

> In EPR, it is critical that it is the same measurement.

I must admit I haven't read the full EPR paper, only post-Bell expositions and excerpts. But you can have perfect spacelike correlations of the same measurement classically as well, e.g. if two particles having opposite (angular or linear) momenta are sent from the midpoint towards distant labs, measuring one momentum will tell you the other one. They must somehow discuss making different measurements no? Maybe they effectively discuss a protocol where the two labs agree on the same sequence of orthogonal measurements. I should read these sources sometime...

Thanks for the ftl reference. It would be astonishing if their hypotheses are borne out. I find it unlikely, but of course the experiments will have to decide, so I'll keep tabs on that. By "foliation" in this context I guess he means a foliation of spacetime amounting to an absolute reference frame. I've seen Tim Maudlin discuss something like that before.

By the way, the article you linked mentions a couple of times the importance of distinguishing signaling from causation or action, but doesn't seem to define how they're distinct. Do you know some more formal article discussing the proposed experiments? The sources given in the article are just to video interviews.

EPR's point is that there is nothing mysterious from a classical perspective of being able to deduce this. They were arguing against the presentation of QM as to there being no fact of the matter about what the momentum is before the measurement and that it randomly becomes whatever it becomes when measured. Their point is that if both particles are randomly collapsing into their choices, then they should disagree at some point unless there is some nonlocal causation happening. Einstein rejected nonlocal causation, reasonable given what he knew at the time, and thus the momentum measurement result must already be preordained by something and it is then like the classical setup.

Bell's work was to show that it had to be the nonlocal causation.

>Do you know some more formal article discussing the proposed experiments?

I do not know of an article, but Maudlin's book Quantum Non-locality and Relativity goes through the various notions of locality and what QM says about it. There is a chapter about signaling and another about causation. It also covers the GHZ scheme which is a non-probablistic version demonstrating non-locality. It is pretty clean.

>Do you know some more formal article discussing the proposed experiments?

I have not read them, but my understanding that Siddhant Das is pursuing these and here is a link to his Arxiv papers which talk about arrival time experiments though I do not know if it is directly about these.

https://arxiv.org/search/advanced?advanced=&terms-0-operator...

Thanks, I had a look at Maudlin's book. It seems the distinction between signaling and causation is that there might be some kind of nonlocal causation that we can't control and so can't use to send a signal.

Local causation is defined as in Bell's Theory of Local Beables, as the probability distribution for values at spacelike separated regions only being correlated with respect to the overlaps in their past lightcones. Or to put it the other way around, there's nonlocal causation if the probability distribution of values in one region depends on values in a spacelike separated region. That's what I'd call nonlocal correlation rather than causation but I guess that's just terminological.

This looks like a pertinent paper from Das but I haven't read through it yet

Arrival Time Distributions of Spin-1/2 Particles (2018) https://arxiv.org/abs/1802.07141

If MWI is true, then nature is local without extra information beyond wave function.

The term is an error due to messy history. Copenhagen program being the first, influenced early quantum physics, quantum behavior was unreal, classical behavior was real. When the term local realism was introduced, it was intended to be philosophic realism, but was confused with classical behavior, because historical baggage was messy.

I mean there is no perspective from which one can obtain a view of all properties of all systems that will not be invalid to another observer.

In my view there is such a perspective: quantum mechanics. So far as we know its predictions are valid for all observers.

But what that means is that we have to readjust our classical conceptions about what a "property of a system" is.

The word "property" in general is just a logical concept, and doesn't carry any intrinsic ontological implications. There can be mathematical properties, physical properties, properties of thoughts and dreams etc., and this way of talking about things doesn't by itself imply any specific ontological interpretation. It's just a feature of the structure of language.

About physical properties specifically, if we derive our concept of physical property from quantum mechanics, instead of trying to retain the inadequate classical meaning, then physical properties are exactly those represented by the state vector: e.g. its projections on to each of the basis vectors corresponding to some observable.

True, as is well-known from the Bell and Kochen-Specker theorems, we can't consistently say that a quantum state has some specific value of its observables independently of interactions with other systems, but this is just the classical conception of a physical property (formalized, e.g., by a real-valued function on phase space).

But quantum mechanics doesn't thereby force us to say that a physical system has no definite properties. Instead, we can reconfigure our conception of physical property to make it compatible with quantum mechanics.

Then in general the properties of quantum states are probabilistic (at least some of them - the dimension of its state space, for example, is not), but the theory unambiguously assigns to a state the probabilities that the various possible measurement outcomes will be observed. These probabilities are among that state's properties, and all indications are that these probabilities are objective features of the state, independently of our ways of representing the state.

In fact the dependence goes in the other direction: this (objectively) probabilistic character of quantum states (among other things, like the quantization of energy exchanges) is what forced us to change the way we think of physical states.

if your definition requires universal observer agreement you already have that issue with special relativity / light cones / the spacetime metric.

many worlds posits a single universal quantum state it's just only partially accessible to observers, which is different from saying that it simply doesn't objectively exist.

maybe it depends on your definition of objective

No objective reality or no single universal frame?

Reproducable reality from x frame seems non-arbitrary if not objective.

That phenomenon was known in classical physics since 500 BCE: https://en.wikipedia.org/wiki/Blind_men_and_an_elephant

I've got a doctorate and I don't really see what you are saying, primarily because "no objective physical reality" is somewhat vague.

QM, for example, is a totally adequate theory of objective reality! it just describes an objective reality with properties which differ to some degree from those intuitive to creatures at classical scales. It may be inadequate in other respects (not invariant, a little unsatisfying wrt the born rule, etc) but it isn't as if it implies NO OBJECTIVE REALITY.

This is what’s meant by no objective reality as alluded to in the article.

https://en.wikipedia.org/wiki/Relational_quantum_mechanics

The claim is not that objects don’t exist, just that they don’t have observer independent properties.

This is what I mean.

And to further clarify, observer independence is referring to the frame itself not that humans imagine the world into being in the solipsistic sense many believe.

I say this because just a few days ago on this forum someone was asserting that without humans the earth would not exist, that human observation instantiates the earth and the earth did not exist before human consciousness.

What do you mean? That according to relational quantum mechanics absolute reality doesn't exist? But absence of absolute reality doesn't imply absence of objective reality. And it's according to relational quantum mechanics, not according to mathematical formalism of QM.

I second your comment. This is where a degree in philosophy would have been useful. The term "objective reality" is just a semantic indirection to a cluster of loosely defined concepts. Okay, what concepts? That whole discussion is philosophy, informed by physics.

See above.

I think language does us a disservice here. I'm reminded of Korzybski's work in Science and Sanity. The interpretation of "truth" depends on which level of abstraction you are operating on. "Every statement is true in some sense, false in some sense, and meaningless in some sense". The term "reality" implies a perceiver, and that perceiver is generating "reality" based on their neurological instrument, which has its own biases based on its prior experience and genetics.

I agree that language other than math fails us here. Nevertheless, I humbly try to convey thoughts that occur in me with these tools.

But the problems described by the parent comment also exist in mathematical language, that’s what Godel Incompleteness is. The problem is inherent to all conceptual frameworks

I would disagree, completeness is not required consistency is all you need really. QM is consistent.

> The term "reality" implies a perceiver

No. Subjective reality is what we experience as sentients. There must be an object reality and imho that is the only statement of truth that can be uttered in language, with "language" to be understood in the sense that Werner Hisenberg uses that term.

So I'm with Bohr, Hisenberg on this matter. We can not 'presume' to speak of the Real with capital R. It exists but it can not be 'encompassed'.

No vision can encompass Him, but He encompasses all vision. Indeed, He Is the Most Subtle, the All-Aware! - Qur'an - 6.103

Leave out the quran quote since that is most definitely not what Bohr/Heisenberg/Others mean when they talk about subjectivity/observation/measurement. See my comment here - https://news.ycombinator.com/item?id=45759220

If you want to discuss Philosophical/Ontological/Epistemological concepts of Reality/Truth etc. there are far better models in Hindu/Buddhist scriptures. The submitted article itself refers to Nagarjuna's Sunyata and Madhyamaka Buddhist philosophy.

The quote seems perfectly fine in illustrating the idea that reality will always transcend our language or thought (to the extent that can be expressed in any language).

And if you appreciate Hindu scripture, that particular quote could have been lifted almost verbatim from the Upanishads.

I don't appreciate the dogmatism that is associated with a lot of orthodox Islam either, but this is something similar to a lot of conservative religious outlooks, as you can find among people identifying as Hindu, Buddhist, Christian, etc. But in fact this particular quote can be seen as antithetical to any such dogmatic position, and it's worthwhile to recognize points of agreement even though you might disagree in other areas.

https://news.ycombinator.com/item?id=45761877

I find your chauvinism is what doesn't belong to HN. Bohr was familiar with Eastern scriptures so it is perfectly understandable as to why he would reference its formulations. I happen to familiar with both and I do not see any discrepency or antagonism in these scriptures. You may not benefit with such comments but it is possible that others will find it useful and informative.

I dislike unnecessary religiosity being dragged in where there is no reason for it.

> I happen to familiar with both

I don't think you are. No Quantum Physicist has ever quoted anything from Quran since there is nothing there (it is the youngest of all religions being only from 7th century AD) which has not been already elaborated in Hindu/Buddhist/Greek/Chinese/Christian philosophies/worldviews. That is why most scientists quoted from those ancient scriptures. There is no need to try and hoist your opinions on them.

Moreover the article specifically mentions Carlo Rovelli drawing inspiration from Nagarjuna's Buddhist philosophy and hence that is the model we should look at to try and understand what he means (and not drag in all and sundry others).

I just saw this comment of yours. It seems you are injecting "religiosity" here.

> I don't think you are.

How could you possibly know? And frankly, with that handle, it seems you are the one with a "religious" issue.

> No Quantum Physicist has ever quoted anything from Quran

Thank you for motivating me...

> It seems you are injecting "religiosity" here.

What is this, childish echolalia? The "religiosity" was right there in your totally unnecessary quote.

> How could you possibly know?

By inferring from your comment(s), duh!

> And frankly, with that handle, it seems you are the one with a "religious" issue.

What does this even mean? If you are referring to the passage i quote in my HN profile, that is the opposite of "any religiosity". Read the cited book for edification.

> Thank you for motivating me...

Hubris to laughingstock.

Quoting the Quran in a positive light is like doing the same with Mein Kampf, except that Islam has caused a lot more deaths over the years. I'd say it's yours that doesn't belong on HN.

If you are going to attack the sacred text of two billion people, it would be better to avoid a lazy comparison to Hitler. Have you read the Quran? Do you understand the historical roots from which it emerged? Do you know how it had been used and abused? What is the relationship between modern science and islam? How has it been used to justify violence? How has it been to argue for peace? Have the people who have used it to justify violence understood the original meaning? How does the violence/body count compare to other dogmatic religions, especially christianity?

There is violence in every ideology. To deny this is to deny reality. Singling out one group as uniquely prone to violence is both uncivil and dangerous in my view. That does not mean that one cannot point out the shadow side, but one should look in the mirror of one's one preferred ideology, whether that is christianity, atheism, scientism, nationalism, rationalism, etc., before casting blanket aspersions at others.

> Do you understand the historical roots from which it emerged?

Justification of one of the biggest, fastest, and most brutal conquests in history? Because everybody who wasn't a Muslim was fair game for killing or slavery? Because all non-Muslim land really belongs to the Muslims?

That's what it actually says.

> Singling out one group as uniquely prone to violence is both uncivil and dangerous in my view.

Something that I very clearly didn't do. And there was nothing lazy about my comparison.

oh wow seriously?

Of course.

I am just a lay person so a lot of the maths is over my head for all of this, but I do try to follow the best I can.

Do you ever ponder that the maths that you try to distill into the “laws of physics” is just too low of a fidelity for such a complicated system?

For example when you capture a gorgeous sunrise/sunset in a photo, and despite you doing every trick under the sun to get a good angle/lighting etc, the photo is never as good as what you experienced in person.

Or maybe you just never experienced the sunrise/sunset shrug.

QM provides the most accurate and verifiable predictions in human history. The follow on from that is that my thoughts can be conveyed to you over a sea of quivering electrons. The one catch is that you must accept that when you are not looking the universe does its evolving in a way that is inimical to your conceptualizations.

You have beautiful way of writing. Do you have a blog?

Thank you so much, I don't.

Just want to +1 and would subscribe if you start one

Thank you for trying.

What were you hoping for?

I apologise as I replied in a shirty manner and deleted as I thought better of it.

I don’t think we’ll be able to really discuss the matter so have a good night!

The idea is that there is no "complicated system", or at least that you are not permitted to concieve of one without describing it in physical detail.

> is just too low of a fidelity for such a complicated system?

I think you're asking questions that some are afraid to ask.

It appears to me that some people have become accustomed to working with approximations, and have accepted the map for the terrain.

Fundamentally, I don't see how you can use continuous math to explain a discrete system.

"It appears to me that some people have become accustomed to working with approximations, and have accepted the map for the terrain."

No, here we are discussing the formalism without approximations associated with an instance of its approximate application.

And QM says "The map is the terrain".

QM is many things

You might want to be a little more specific, and rely less on approximations.

I am aware of what the Copenhagen interpretation states, thanks

To what approximations do you refer?

Here we discard Copenhagen and move forward.

Take your pick

Schrodinger/Dirac/Feynman.

A wave is a product, trigonometric functions do not exist.

Gerard hooft was on Curt Jaimungal's youtube channel a while back, I generally agree with him, discrete systems cannot be explained by real numbers, only integers

Not following youtube, sorry.

uhuh, well I'm sure you know how to use a search engine

For non-relativistic QM, the QM formalism is provable from Bohmian mechanics, an actual particle theory. BM starts from particles have locations the change continuously in time via a guidance equation using the wave function of the universe. One may choose other theories to explain quantum phenomena, but to say "There is simply no physical machinery to support an objective reality, period." is just false, at least in that realm. As for relativistic QFT, there are plausible pathways using Bohmian ideas as well though nothing as definitive as BM has been firmly established.

I would also say that any theory that does not have room to say definitively that I exist is a theory that is obviously contradictory to my experience and is therefore falsified. There has to be room in the theory for at least me. Additionally, I would certainly value much more a theory that has room for the rest of humanity more than one which questions the existence of everyone but me. I am not even sure what the point of a theory would be if it could not account for collaborative science being done.

QM does not deny you existence, it rather denies you a complete objective description of how you exist. Or perhaps it says that your existence is not an objective phenomena.

Would you mind clarifying in which of these 3 dictionary definitions of the word objective my existence (in the sense of the "particles" of my body) is not objective? Or maybe these definitions are not exhaustive? Perhapse the term objective has become overloaded.

objective

adjective

Not influenced by personal feelings or opinions when considering and representing facts; impartial. “Historians try to be objective and impartial.” Synonyms: impartial, unbiased, neutral, dispassionate, detached. Antonyms: biased, partial, prejudiced.

Existing independently of the mind; actual. “A matter of objective fact.” Synonyms: factual, real, empirical, verifiable. Antonym: subjective.

Grammar. Relating to the case of nouns and pronouns used as the object of a transitive verb or a preposition.

BM is objective, and indeed deterministic. I'm not exactly sure what you mean by "complete" but it has all the same predictions as other interpretations of QM. It has some odd quirks however, such as explicit non-locality.

Since EPR+Bell showed that nature is non-local, it is a feature, not a bug, to be explicit about how non-locality happens. Collapse theories are also explicitly non-local.

That's one position in a century-long debate. But there are other assumptions than locality in the proof of Bell's Theorem, which other interpretations of QM relax. Like having single measurement outcomes (many-worlds), or observer-independent states (QBism).

In terms of quirkiness, how would you rank them? I feel like nonlocality is far less quirkier than saying that all possible outcomes of a measurement happen even though we just see one. Also standard QM has the quirk of being nonlocal. So QM is just quirky.

There are many that I don't understand very well, so I'm reluctant to rank them. My tendency is to be skeptical about how clearly us humans can see the underlying reality of things, so I find epistemic interpretations like QBism appealing on that basis.

The "every outcome happens" aspect of many worlds is a lot to accept. Otoh that's what you get if you take quantum states to be ontological and universal. My problem is more to do with how the Born rule falls out. There are some arguments for it based on decision theory, but I find the step from "this is how a rational betting agent maximises winnings" to "this is the objective probability of a scientific observation" uncompelling.

I'm not sure what you mean by "standard QM". There's the mathematical framework - which is effectively a way of calculating probabilities of measurement outcomes - and then there are interpretations, which assign ontological status to some/all of the mathematical objects. Non-locality properly applies to the latter, since you cannot say that the "real" physical state of a particle has changed until you've said which parts of the mathematics are real.

I don't at all begrudge you your logical predictive fictions.

Your conclusion rests on the assumption that QM's description of reality represents the ontological truth. And such a 'truth' is not provable. However, as you already mentioned, it doesn't matter as QM provides the strongest epistemological claims, and this is what matters in the end.

I think otherwise. I am precisely saying that QM as a formalism denies ontological truth in the first instance. You have to do something like the BM guy above is embarking on.

Donald Hoffman, Bernardo Kastrup and other idealists have been saying this for years

https://youtu.be/yqOVu263OSk?si=M3fcLbJneZ0S5Jpq

Adivita Vedanta, Buddhism, mystics and perennial philosophers have been saying this for centuries

https://youtu.be/cwcft4auszA?si=1vYsny6jZb--IE_0

Wolfram is also taking in the same vein but in a different approach

https://youtu.be/8SD9WgPCZ28?si=t8XvVfJV8qi-K_0q

Ie something is up and spacetime is NOT fundamental

Some philosophers and mystics may be metaphorically correct, but that's not evidence of anything. Lots of people say really wrong things about reality too.

Once the notion of objective truth is relinquished, what ontological or epistemic status remains for reasoning itself? Is it to be understood as a pragmatic construct, or as something with deeper necessity beyond empiricism?

Deep necessity, we follow logic so we are not grunting beasts.

But where does logic exist in, then? Does it not need consistency to be useful? And what causes the consistency? It's turtles all the way down.

Logic does not exist in a physical sense, but try to think without it. For example, try to think without the law of noncontradiction. Can you categorize?

I tried quite a lot. I've come to the conclusion that thinking (and logic) is probably some pattern that only seems interesting to itself.

(Yes, I am aware of the otherwise nonsensical concepts "pattern" and "interesting".)

My instantiation of logic isn't physicalized? Is there unphysicallized logic?

To me, what makes sense is that there is one reality (or I guess, our reality is unity), and everything in it, including “living” beings and “intelligence” is inseparable from the singleton. So trying to observe an object or an event, is the same as reality observing itself. It wouldn’t surprise me that the feedback loop of this is what we perceive as observer dependent attributes. Whether this reality is an objective physical reality or something else entirely is irrelevant and does us no harm.

What do you think about this blog post: [1]? It seems to be promoting very similar ideas but I lack education to evaluate its claims.

[1] https://andercot.substack.com/p/theres-no-single-objective-r...

Hm, I wrote this while reading the beginning, and then it rapidly went downhill with alien conspiracy theories.

> What staggers the mind is the corollary that no human has ever erected a truth.

Hell, you don't need a physics degree for this, nor even QM, just a robust grasp of the limits of empiricism. Hume connected the dots centuries ago.

I see this as decidedly non-Humean. Why be Humean anyway?

Nice example of physics tumbling into meaningless metaphysical nonsense.

Nice example of hurling meaningless invective.

So is it all a dream?

This is not radical. His thought is clearly in line with a very old and very mainstream philosophical tradition called "idealism," and I was surprised to see this go unmentioned in the article. See: https://plato.stanford.edu/entries/idealism/

> Within modern philosophy there are sometimes taken to be two fundamental conceptions of idealism:

> 1. Something mental (the mind, spirit, reason, will) is the ultimate foundation of all reality, or even exhaustive of reality, and

> 2. although the existence of something independent of the mind is conceded, everything that we can know about this mind-independent “reality” is held to be so permeated by the creative, formative, or constructive activities of the mind (of some kind or other) that all claims to knowledge must be considered, in some sense, to be a form of self-knowledge.

Among mainstream philosophical traditions, idealism is IMO the weakest, as it's inevitably solipsistic. Physicalism has become strongest.

I take issue with the “stronger” characterization. Maybe I have a vocabulary problem. However…

Your own perception of the physical world is, by necessity, solipsistic. Your own experience of the physical world is in your own mind. Without that perception, you can’t say it exists.

We know that it’s possible to have this experience of perception without the physical world, as long as your mind exists. In other words, this could all just be a simulation being dumped into your mind without the physical world as you “know” it existing. Hence, idealism.

Whether one is stronger (or more true?) than the other really doesn’t affect how you function within reality - you’re constrained by what you perceive as the physical world.

Indeed. Science isn't the study of the universe, it's the study of our experience of the universe.

Physics tends to imagine that a mind is a neutral blank screen that represents reality faithfully and accurately. But that's nonsense. It's a process that imposes certain kinds of perceptions.

The conceptual metaphors we use - position, mass, velocity, time, causality - are products of that process, not fundamental representations.

It's possible other minds have unimaginably different experiences based on unimaginably different metaphors.

Some of those might have potential mappings to our models, others might not.

Your vocabulary is fine. I think that idealism is necessarily weaker than other ways of viewing the world; it has problems that were repeatedly noted throughout the 20th century in major works by Wittgenstein and Heidegger, among others. (In fact, it can quite fairly be said that most of 20th century philosophy is a reaction to the fuzzy, yet superficially persuasive, idealistic tendencies of the 19th. Analytic philosophy is 100% a reaction to this.)

Per the Wittgenstein, you have, e.g., the "private language" problem: https://plato.stanford.edu/entries/private-language/

Per Heidegger, well, the entire notion of "being-in-the-world" is a response to idealism. This is the notion that we first encounter a shared world of use, tasks, and significance (hammering, writing, speaking with others,) not private "ideas." So the world as you experience it isn't constructed within your head alone; the outside is always with you. You're embedded in an objective field -- or, at the limit, a consensus field.

As a general rule, you can't make sense of science and the commons as purely private occurrences. One's theories are often false; one is often genuinely surprised.

Besides, even classical idealists need something "beyond" representation (Kant's thing-in-itself; Schopenhauer's subliminal Will) to make sense of why experience has the structure it does. That is, the idealist view silently re-imports something non-mental to ground the mental.

Of course, we could be Boltzmann brains, dreaming clouds of charged gas in the sky, or we could be controlled by Cartesian Demons... and that is where strong idealism eventually leads... but I think that these views should be disfavored even on empirical grounds, for instance in your continued existence.

People interested in this subject might enjoy this interview with David Albert [1], as well as this interview with Tim Maudlin [2], who offers a different perspective from Albert. They are both philosophers of physics, or in other words physicists working on the foundations of physics.

[1] https://www.youtube.com/watch?v=JR2sMeXLuLw [2] https://www.youtube.com/watch?v=3riyyEmWwoY

They have written some good books too.

I especially like 'Quantum Mechanics and Experience' by David Z Albert (he's got a very peculiar style of writing that I enjoy), and 'Quantum Non-Locality and Relativity' by Tim Maudlin.

Not easy reading, but manageable if you have a physics degree.

Thank you for the links :)

Carlo Rovelli: 'Time Is an Illusion' - https://www.youtube.com/watch?v=PuLaUYQFIwg

I think the idea of an "external reality that follows certain rules and humans operate in" could itself be a kind of evolutionarily-advantageous belief, even if it's not actually true in a quantum physics sense. In other words, we become capable of science and technology only after assuming there are scientific rules to be found.

There are many concepts like this throughout human history - another one I'm thinking of is the (in the West) monotheistic idea of narrative history/time. By framing time as something that can have a beginning and end, you enable or at least incentivize "progress", and mentally unlock the ability to work toward some idealized future, rather than accepting that time is cyclical and/or without some notion of moving forward.

I dare say the phenomenon is real and our understanding is lacking.

Most folks don't understand what Physicists mean when they say "Reality doesn't exist at the Quantum level". Words like "Reality", "Illusion" etc. mean quite different things when applied at quantum level vs. classical-macro level.

The best book to get a grasp on the above is Werner Heisenberg's classic Physics and Philosophy: The Revolution in Modern Science. The introduction by Paul Davies itself is worth the price of the book since it highlights the main issues quite clearly.

At the fundamental level quantum systems have an inherent indeterminism (as a consequence of the famous uncertainty principle) which is what we find hard to grasp. It does not mean total anarchy but that you can only calculate relative probabilities of the alternatives in the answer set i.e. it is a statistical theory. Thus it can make definite predictions about sets of identical systems but generally cannot say anything definite about a specific individual system.

For example, an electron doesn't exist as a single thing occupying a specific trajectory around the nucleus. It only exists as a set of potentialities occupying an area of space viz. the so called electron shell. Only when a measurement is made does a electron-with-position or electron-with-momentum can be said to come into existence (since before the measurement there are only probabilities and you cannot measure both position and momentum sharply simultaneously). It is in this sense that the Reality of an electron is said to only exist in the Measurement/Observation and cannot be said to exist otherwise.

The other side of the coin is that, Modern Neuroscience tells us that the Brain itself is wired to Construct Reality from incomplete data and we seek/construct patterns where there are none. See for example Cordelia Fine's A Mind of Its Own: How Your Brain Distorts and Deceives and watch this Ted talk by Susana Martinez-Conde Reality is made of illusions—and we need them - https://www.youtube.com/watch?v=FzDw07RqCSs

Another Ph.D. physicist here. Any popularization of quantum mechanics (or quantum gravity in this case) can quickly degenerate into potentially foolish, or even harmful, metaphysical speculation. Physicists are in the business of finding the best set of mathematical rules that describe "If the conditions A exist, then B happens [with a certain probability]." The frustrating part is that about 100 years ago, quantum mechanics provided a set of rules that didn't have an easy intuitive interpretation (i.e. that quantum mechanics is not both a "real and local" theory.) Yet it is wildly successful for what it does, and the mathematics is crystal clear. (By the way, regular non-relativistic quantum mechanics can be interpreted as having "no reality", no fancy quantum loop gravity needed; see e.g.https://arxiv.org/abs/quant-ph/9609013 - more precisely, only correlations exist.)

Taken to its metaphysical conclusion, though, "there is no objective reality" can lead to harm. So, I guess morality is all a matter of perspective? That can be used to justify anything. We do seem to have an emergent reality (at least the one I am experiencing at the moment) that is held in common - just because the underlying mathematics is hard to interpret doesn't justify "anything goes", or my crazy belief is just as good as your crazy belief.

So although it is fun to think about, don't take "there is no objective reality" too seriously - you still have to go to work, you still have to pay your taxes.

> Physicists are in the business of finding the best set of mathematical rules that describe "If the conditions A exist, then B happens [with a certain probability]."

Physics can't claim domain over the study of reality and then say that reality can only be studied using mathematical rules. You can either say physics is the study of mathematical physicalism and stick to your mathematical rules, or you can say physics is the study of reality and be open to alternative ideas outside of mathematics to describe reality. Otherwise you're just precluding the conclusion of what you're supposed to be studying, that reality can be described by mathematical rules.

> Taken to its metaphysical conclusion, though, "there is no objective reality" can lead to harm.

So we should hide reality under a rug if it could possibly lead to harm? The truth is the truth, your objective as a scientist should be to follow the evidence not police morality. History shows that the truth tends to lead towards a better world anyway. I'm sure the Church was afraid of the decay of morality from atheists if they learned that God doesn't keep the planets in motion.

>Physics can't claim domain over the study of reality and then say that reality can only be studied using mathematical rules.

I never claimed that physics claims domain over all studies of reality - in fact I quite limited the domain of physics to finding the "best set of mathematical rules" that gives a certain probability of events happening.

>Otherwise you're just precluding the conclusion of what you're supposed to be studying, that reality can be described by mathematical rules.

Just the quantifiable part of reality - the "metaphysics" parts (e.g., why are we here? Is that a sensible question?) aren't the purview of physics (although physicists generally have their own opinions, as does Prof. Rovelli...)

>So we should hide reality under a rug if it could possibly lead to harm? I never said hide it - I said such metaphysical beliefs could lead to harm. So be aware that the popular interpretation of there being no "objective reality" (which relies on interpreting something mathematically rigorous in physics) can be twisted into justification for nearly any action.

Alright fair enough, I apologize I guess we’re actually on the same page then

You, too, are practicing and advocating for a philosophy here.

Also, the lack of objectivity in the universe doesn't necessarily mean that nihilism is the ONLY way to go. Existentialism, for example, doesn't accept an objective reality either, and folks have found ways to make morality (and even religious faith) fully compatible within that framework.

Obviously, it's not good to delve into metaphysical speculation, as it often clearly leads to junk conclusions written by people who don't have the credentials to account for what the actual science (OR the actual philosophy) says.

But I do wonder what it would be like if modern physicists were more willing to pair up with modern philosophers once in awhile. I would very much love to see a collaboration between the two fields to explore what a subjective universe really MEANS to us as both a species and as moral beings in that universe.

I, very much, would love to see what some of these implications are, as written out by the folks who actually understand the science. Even if there's no true consensus among them, just learning what the different possibilities might be could be very enlightening.

Haha, the author observes that basis transformations don't change the state and concludes that there's no absolute state of being.

I like the article. And I applaud any physicist trying to come to grips with our conceptions of reality AND reading up on philosophy. That being said, he's neither the first nor will he be the last, nor is "perpectivism" in epistomology a new thing. I like, however, how he is throwing in several streams (I saw James, Nietzsche, Kuhn, and even Rorty and Wittgenstein II) of thought, centered on Kant's ideas of the noumenon and its inaccessibility. I don't think I agree with him, though ;)

If I had to label him, I'd say he is mostly an anti-realist.

Mario Bunge was another physicist who deeply engaged with philosophy (he taught philosophy at McGill University). Interestingly, the conclusions he arrived at were quite the opposite.

> There is no objective reality, according to Rovelli — only perspectives. “This is very radical, because you can no longer say, ‘This is a list of things in the world, and this is how they are.’"

Perfectly in line with his political views, when he's a guest on the Italian TV's, or on social media he spend so much time defending the reasons of the Russian in the Ukrainian invasion. With hosts that often asks physics and political questions in the same set, as if his way of looking at reality gives him any ground truth. I'm wondering how much his physics and political views overlap. Such a delusion for me as Italian, I stopped reading his books for this reason and because at some point, after the wonder effect of reading about quantum worlds, I was left with the sensation that I read a lot and nothing at the same time

The thing with idealists in the philosophical sense is that they're typically not very well grounded in reality. Not saying it's always drugs/psychotic breaks/deep meditation, but often it is. Even more so with the panpsychists.

As former physics student, a lot of ego and little physics IMHO. Theoretical physics is pointless without experimental tests. Personally, I prefer physicists spending more time in the lab or in classroom than on mass media

Some degree of engagement with popular opinion and culture might be needed to keep on getting money for the experiments and grants for the students.

But I take the point you are making.

Also physicists tried the "keep out of the public and just do the science* thing and now everybody thinks physics has made no progress for 50 years and the masses think "string theory" is anything more than a topic in some books not aimed at physicists

Experimental tests happen after theoretical physics figured out what tests should be done.

I haven’t heard about his views on Russia but that’s worth looking into since I also have his books.

Just a quick nitpick as a fellow Italian: “delusion” (“illusione”) is a false friend of “delusione.” Maybe you meant “disappointment”!

thanks for the false friend! Let me share, one the many, critic articles to rovelli https://www.ilfoglio.it/russia-ucraina/2023/04/11/news/caro-...

Related. Others?

Carlo Rovelli on challenging our common-sense notion of time - https://news.ycombinator.com/item?id=17893865 - Sept 2018 (74 comments)

Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time - https://news.ycombinator.com/item?id=17376437 - June 2018 (143 comments)

For a counterpoint see:

https://arxiv.org/pdf/2105.13338

And my own personal take on it:

https://blog.rongarret.info/2014/10/parallel-universes-and-a...

https://arxiv.org/abs/2105.13338

Could you please cite the abstract pages instead of the pdf.

The pdf is linked off the abstract page anyway, in case the reader wants to download that after reading the abstract.

The abstract pages usually have other bibliographic goodies that can be easily accessed.

I love Rovelli, but to me he’s just another proof that if you look for too long into the quantum abyss, the abyss is gonna eventually look back at you…

And wink...

Time is not an illusion. It can be experimentally verified. There is a flow in a certain direction. Carlo is saying that time is not absolute, every point on the space is a clock, essentially trying to convey the core concepts of special relativity with engaging interaction.

Genuinely curious - what experiment can be used to verify the existence of time?

In engineering and sciences practice, existence of time is vitally accepted and measured.

We have experiments verifying not only existence of time but relativity of time is established strongly. There are couple of prominent topics supporting this view, links to peer-reviewed works.

1. Einstein's general relativity is first experimentally verified by Sir. Eddington https://en.wikipedia.org/wiki/Eddington_experiment The deviation is actually about time as well, interplay between geometry and gravity.

Subsequently for special relativity "Experimental Establishment of the Relativity of Time' https://journals.aps.org/pr/abstract/10.1103/PhysRev.42.400

This is actually what Carlo trying to explain in his YouTube interview.

Experimental Tests of General Relativity https://www.annualreviews.org/content/journals/10.1146/annur...

2. Existence of Biological clocks measuring time is understood by gene regulation and molecular setting:

Biological clocks https://www.pnas.org/doi/abs/10.1073/pnas.96.16.8819

3. Entropy production

On material systems. Evolution of time is tied to entropy production, for example using fluorescence spectroscopy

Measurement of Stochastic Entropy Production https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.97...

4. Relativistic effects on GPS.

Relativity of GPS measurement https://journals.aps.org/prd/abstract/10.1103/PhysRevD.68.06...

Satellite test of special relativity using the global positioning system https://journals.aps.org/pra/abstract/10.1103/PhysRevA.56.44...

These support's Carlo's explanations quite well.

5. Quantum Metrology

Even though causal ordering is not definite in quantum mechanics, once things measured they "collapse" to ordering.

Experimental aspects of indefinite causal order in quantum mechanics https://www.nature.com/articles/s42254-024-00739-8

Once things are measured, things should obey thermodynamics.

6. Atomic clocks and synchronisation, they are used to measure "time" in all sorts of scenarios.

The Measurement of Time: Time, Frequency and the Atomic Clock https://www.amazon.com/Measurement-Time-Claude-Audoin/dp/052...

7. Stellar navigation. Even though this sounds science-fiction, but it is indeed possible to measure time using pulsars.

Spacecraft Navigation and Timing Using X-ray Pulsars https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2161-4296....

I am puzzled that Carlo Rovelli associates the perception of time flow with entropy increase. Entropy increase allows to define the direction of time, but it cannot explain why we perceive the time flow.

Merely disagreeing with a guy like Rovelli on physics feels like hubris. :)

But agree with you in this case. Animals perceive the flow of time because we have memory and prediction abilities. This gives us a psychological arrow that aligns with the thermodynamic arrow.

The thermodynamic arrow appears also because we have memory and prediction abilities.

Concepts in statistical mechanics by Arthur Hobson

Publication date 1971

https://archive.org/details/conceptsinstatis0000arth/page/15...

Concerning the concept of time, it is clear that the generalized second law is related in some manner to the question of the "direction" of time. It is sometimes asserted that the second law explains the distinction between past and future, or that the future may be defined as the direction of increasing entropy. This assertion says that the second law is more fundamental than the distinction between past and future.

It seems to the author that the above assertion is wrong. It was seen in Section 5.2 that the generalized second law is derived from the distinction between past and future; hence the distinction between past and future is more fundamental than the second law.

The following statement seems to be the most fundamental physical assertion which can be made regarding past and future: we can classify all instants t into two categories; the first category contains those instants about which experimental data is (or could be) known, and the second category contains those instants about which no experimental data is known. The first category is conventionally called the "past" and the second is called the "future". The instants may be labeled with real numbers running from -∞ to +∞, in such a way that the "past" instants constitute a set of the form (-∞ < t < t0), and the "future" instants constitute the set (t0 < t < +∞). The choice of the positive direction as the future is purely a convention.

According to Sections 5.2 and 5.4, irreversibility and the generalized second law are derivable from the existence of the above two categories of in-stants: an "information-gathering category" (the past), and a "predictive category" (the future). The existence of these two categories seems to be a fundamental feature of nature, not explainable in terms of the second law or in terms of any other physical law.

Well, I am puzzled that Rovelli is not aware about the great debate in modern philosophy about time series A versus time series B that was started in 1908 by a paper on unreality of time by John McTaggart. A consequence of that paper is that perception of the time flow cannot be reduced to a physical process like entropy increase etc. So far nobody was able to disprove that.

I wouldn't be so pessimistic. Actually, it does explain why we perceived the time flow: It is called Thermodynamics. One can compute and verify scientifically, measure time flows from biological clocks to GPS systems.

In 1908 philosopher John McTaggart published a paper on unreality of time. Modern take on that is that physics describes only B time-series with static time without any notion of time flow. The time flow requires A-series or dynamic time which nobody so far was able to reduce to static time of B-series and physical equations.

For example, if one takes a video of water heated in a bowl then thermodynamics can tell that at the beginning of the video the water is cold, that at a particular timestamp it should boil etc. But thermodynamics cannot explain why I see the water is bubbling with all movement. I.e. with thermodynamics the world is static 4D structure. It does not explain why consciousness perceives 3D slices of that one by one.

> John McTaggart published a paper on unreality of time

Thanks. Great point.Special relativity covers these, I think. Carlo's interview here explains time from special relativity perspective. He doesn't say time doesn't exist or unreal, but we have some misconceptions in our daily Newtonian intuitions.

https://www.youtube.com/watch?v=PuLaUYQFIwg (Sorry if it is already posted in this tread).

> "Why consciousness perceives 3D slices of that one by one."

Philosophicaly not resolved problem, probably. But in general, in physics, entropy production explains this perception, i.e. modern stochastic thermodynamics.

Philosopher Huw Price published a few articles and even a whole book pointing out that entropy does not explain flow of time at all using different arguments than McTaggart's.

A simplified analogy is a fence with a color gradient from black to white. When one walks along the fence, there is a perception of a color flow from black to white. But there is no flow in reality, just a static gradient with the flow in the eyes of the observer.

Price also pointed out since physics does not explain time flow or even its direction, we cannot rule out existence of creatures with flow of time opposite of ours. Nothing in physics contradicts that.

And then whole notion of entropy is purely statistical property coming from a lack of knowledge of the initial conditions. Both classical systems and quantum wave function of the whole universe follow time-deterministic equations. So any future or past states of the system contains exactly the same amount information and there is no inherent notion of entropy. But since we do not know the initial conditions precisely, we need to apply statistical reasoning which under certain assumptions leads to the notion of entropy and conclusion that in past that was lower.

This has nothing to do with perception, because the difference between A and B can't be detected by science and measurement devices, perception is vastly more lax method of measurement and has no chance to perform better than science.

Yes, detection is an unresolved problem and a critical point from modern causal inference that purely statistical methods may not able to differentiate direction; even though there are quite a few algorithms using asymmetric distribution argument, i.e., KL divergence being asymmetric.

Maybe someone can help me wrap my head around this. Let's say you have a box of gas in a low entropy state: all the particles are on one side of the box. A moment later, the particles will have spread to the other side of the box, so the entropy is lower. But to say "a moment later", we're assuming a quantity called time. I'm confused how you can see this in reverse: "because the particles spread to the other side of the box, a moment passes".

The perspective is kinda like this:

All moments are equally real, like the movie frames on a film roll. The laws of physics say how a point on one frame relates to the same point on the neighboring frame, just like they say how a point relates to a neighboring point on the same frame. You can cut out all the frames from the film roll and stack them on top of each other, resulting in a “block” of points in space-time.

Einstein’s relativity implies that there isn’t a unique way to slice that block into same-moment-in-time frames; instead there are many different ways. Nevertheless, the laws of physics specify how the points within the block relate to each other (e.g. in terms of electro-magnetic field strength and orientation at each point, and all the other physical fields), independent of the particular slicing.

It happens that these physical relations give rise to a structure/flow/weaving that is different along one direction than along other directions. It also happens that along that particular direction the structure implies an increase in entropy, if entropy is calculated on slices perpendicular to that direction (= the increase is from one slice to the next). And that is what has us perceive that direction as time.

But all that really exists is the four-dimensional space with a-priori no distinguished direction, just physical laws describing how points in that space relate to each other. The laws happen no imply that the points will generally be in a pattern in which some direction looks different from the others, and will have a structure that results in us perceiving that direction as time. But there is no externally flowing time, it’s just a pattern within that immutable block of physical reality.

Note: The currently accepted laws of physics do have time as an a-priori dimension. But the idea is that we will come up with laws that don’t have that presumption, and which instead will have time as an emergent property, connected to directions of entropy increase.

You mean, higher?

Seriously, it would interest me when they enable the creation of something akin to a warp drive.

- First, because it would be a way to test these hypotheses

- Second, because it would dramatically expand humanity's playground, even if it's only in the solar system in the first step.

- Third, because building a Warp drive would be good for the economy. Currently, we have no equivalent to the space race. We have AI, but there are doubts that it will enable more than incremental steps.

What hypothesis would be tested by a warp drive?

All these theories question the nature of space, time, and matter:

- Loop Quantum Gravity

https://en.wikipedia.org/wiki/Loop_quantum_gravity

- Causal Set Theory

https://en.wikipedia.org/wiki/Causal_sets

- AdS/CFT & Tensor Networks

https://qspace.fqxi.org/videos/121/a-tensor-network-approach...

- Relational Quantum Mechanics

The one discussed here

- “It from Qubit”

https://www.scientificamerican.com/article/tangled-up-in-spa...

- Thermodynamic Gravity

https://en.wikipedia.org/wiki/Entropic_gravity

- Noncommutative Geometry

https://en.wikipedia.org/wiki/Noncommutative_quantum_field_t...

The core idea of relational quantum mechanics is that when we talk about an object — be it an atom, a person or a galaxy — we are never just referring to the system alone. Rather, we are always referring to the interactions between this system and something else. We can only describe — and in fact understand — a thing as it relates to ourselves, or to our measuring devices.

Lee Smolin has gone down a different track but with similar spirit of sorts. Carlo poked fun at Lee for all the work they've done together despite disagreeing on so much in his recent talk[1] at Lee's Fest[2].

Smolin has named his approach the Causal Theory of Views, in which he postulates that spacetime emerges from events, ie relational interactions. This[3] interview, which is a few years old now, contains a decent high-level explanation. The idea that kinda overlaps with Rovelli he explains like this:

The theory that I've been looking for would take advantage of the fact that the notion of locality and nonlocality is key to understanding quantum mechanics, and then try to understand that with the lens of the unification of quantum physics with space and time, which is quantum gravity.

In both approaches, there's a principle, which is the idea of relational physics—that the degrees of freedom, the properties of whatever it is that's dynamical that you're studying, arises from dynamical relationships with other degrees of freedom.

In other words, you don't have absolute space, you don't have particles that occupy points or follow paths or trajectories in absolute space. You have many particles which, between them, allow you to define relative motion.

Lee has given several talks[4] at PIRSA since that interview with more details as he's developed his idea.

So while both go hard on the relational aspect, they disagree on some fundamental things. Rovelli thinks time is an illusion, but in Lee's CTV time is real and space is the illusion (emergent).

Who knows if it'll pan out or be a dead end, but since the quantum physics community has been headbutting the fundamental issues with little progress for so many decades, it seems prudent to try some bold approaches.

[1]: https://pirsa.org/25060030

[2]: https://pirsa.org/c25023

[3]: https://www.edge.org/conversation/lee_smolin-the-causal-theo...

[4]: https://pirsa.org/speaker/lee-smolin

I'm not a physicist by any means but I was just thinking something similar only a few minutes ago... that humans (or anything) ageing probably only exists as a function of the passage of time, but if all matter stopped moving, even in an isolated area, there is seemingly no longer a passage of time there. So maybe time itself only exists insofar as our ability to measure relative changes to matter.

A crazy thought I had in my sleep: What if dark matter only exists as a random noise generator to keep the simulation from halting? /s

My brain is weird.

> but if all matter stopped moving, even in an isolated area, there is seemingly no longer a passage of time there

This is kinda what would happen in Penrose's Conformal Cyclic Cosmology[1], as far as I can gather. In his theory, he posits that in the far future, matter has decayed to radiation, and energy has been redshifted into infinity thanks to the expansion of space.

As such, in a local region things would seemingly be frozen in time. Nothing would change, entropy would not increase, and hence no apparent passing of time.

That said, his theory is pretty speculative. But fun to think about.

[1]: https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology

I must admit the foundation of the argument presented punches well above my understanding, but I recently read Carlo Rovelli's short work "The Order of Time" and found it wonderfully engaging and relatable.

A person proposing to stop or limit military aid to Ukraine "for peace" has decidedly radical view on reality, that's for sure.

> My intuition is that the overall flow of time really could be like the rotation of the sky every day. It’s a majestic, immense phenomenon, but it’s actually an illusion. This is a totally perspectival understanding of the second law of thermodynamics. It’s real in the same sense that the rotating sky is real, but it’s real only with respect to us.

And later:

> Our community has wasted a lot of time searching after speculative ideas. What we need instead is to digest the knowledge we already have. And to do that, we need philosophy. Philosophers help us not to find the right answers to given questions, but to find the right questions to better conceptualize reality.

I think it’s odd that a physicists proposes a new theory without suggesting experiments that could falsify the theory.

pretty much all experiments that could have been done were done

and you can rearrange equations to make them better fit together without needing new experiments

That second quote hits hard. Physics got so good at answering questions that people forgot to check if they were asking the right ones. Same thing happens in tech - we're really good at optimizing for metrics, terrible at asking if those metrics matter.

This falls in line with the absolute rarity of questioning your own assumptions. In my experience few do.

The amount of people looking outward only is too damn high, as the saying goes.

Baader-Meinhof complex in action: I have _just_ ordered a book of Rovelli's (Reality is Not What It Seems - https://en.wikipedia.org/wiki/Reality_Is_Not_What_It_Seems), it should be in my hands by the end of the week. I am fascinated by the ongoing work in quantum gravity, it's tantalising by its nature.

This is a great interview and I must say I like the man a lot more than I did before. He has articulated something here that I have long felt: that it is as important in politics as it is in philosophy or theoretical physics to be able to state one's assumptions, to suspend one's assumptions for the sake of argument and to drop/change one's assumptions in the face of evidence.

I feel like this is a vital skill that we, as a society, need now maybe more than ever, in literally any field in which there is any meaningful concept of "correct" (which I think is most fields). I also think it's a skill you basically learn at university - and that that is a problem. I don't know what an approach to cultivating it more widely would look like.

Yawn.

He still obviously believes in some sort of underlying "reality" in spite of his claims to the contrary.

The wavefunction evolves as if it were a single, global, observer-independent object.Between interactions, nothing “happens” to it. It doesn’t care who’s looking. It just evolves — deterministically, coherently, globally.

This is not a “perspective.” This is a God’s-eye view — the very thing Rovelli says doesn’t exist. If there were no underlying system, how do you compute interference?

He is in practice unable to accept the parsimonious and experimentally supported idea that very simply: regularity is only achieved at the price of generality.

Rovelli says it, but lives in denial. He cannot accept it because it would force him to abandon the global wavefunction — the silent god of his physics.

>Richard Feynman said things like “Philosophers are as good for science as ornithologists are good for birds.”

Huh? But that's an argument for philosophy, not against it. Peacocks were left alone and look where their evolution ended up, such misdirected result won't be beneficial for science.

How do these quantum + gravity loops/patches evolve continuously w/o time? The more I learn about theoretical physics & physicists the more I'm convinced these people are basically idiot savants.

Not sure about this specific theory, but I imagine it's similar to Wolfram's Digital Physics project, where you have "ticks" that apply the rules to eems, and then out of the maze of rule applications we somehow get time as we perceive it.

I am willing to grant that time is indeed an illusion b/c we do not have perfect perception of reality but it seems like all these new developments are squirreling time away into another part of the theory by calling it something else like "dynamics", "rule application", "evolution", etc. The physically relevant relations happen one way or another & whatever they're calling the deltas between the new primitive states & their evolution is still referring to some coordinate (whether implicit or not) that is essentially the same thing as time.

Moreover, it's pretty obvious that when they're describing the theory they can not avoid evoking temporal language & metaphors so it's difficult to take them seriously when even they can't avoid describing what's going on w/o referring to time.

My naive way to think about a reality without time is that all the possibile states of reality are already there, all together. The rules are about how to move from one state to another one, like water flowing on the side of a mountain.

Those rules might be be deterministic or there may be a roll of a dice. Then what we perceive as time is the sequence of states, the memory of previous states. No ticks are needed: there might be no central clock like in CPUs, each part of reality might apply those rules continously and move the global state from one state to another one.

But this is not physics as we are doing it now, it's presocratic philosophy. They got the idea of atoms right among a number of ones that turned on wrong.

There's no motion in what you've described. You're describing a crystal or maybe a hologram. David Bohm is the main physicist I know about who has written on this topic but I'm sure there are a few others by now as well who are taking holographic principles seriously.

at a macroscopic level obviously what they describe must look like "time" to match what we see

but time ticking because of some dynamic interaction mechanism between some things (like a mechanical clock) is very different than some fundamental/abstract/irreducible "time" which just is (like in einstein)

Not a physicist but this echoes my feelings when people talk about time as an emergent phenomenon.

I'm not a physicist either but this stuff isn't magic. Most of the mathematics used by physicists isn't complicated if you've managed to get past calculus.

At this point, numerous exotic mathematical tools from Langlands program, Lie algebras, algebraic geometry and topology have been used in physics.

I do agree that you can go quite far with calculus, linear algebra, and probability. But I do think that you overstate the case.

Algebraic geometry isn't any more complicated than multi-variable calculus. It's certainly more abstract but you get used to it after a while. Schemes¹ are not difficult to learn if you know basic commutative algebra & topology. If you don't know basic commutative algebra then you'll have a tougher time but it's again something that can be learned w/ enough practice & patience.

¹https://webhomes.maths.ed.ac.uk/~v1ranick/papers/eisenbudhar...

Very off-topic but use of "b/c" and "w/o" in all your posts makes you stand out quite a bit. And the particular use of "&", as well.

If you read a lot of analytical philosophy & meta-mathematics literature you'll notice it's not unique at all. That's how I learned the short-hand conventions.

Sounds like presentism: time exists, but is emergent, not fundamental. Well, whether emergent phenomena exist is a philosophic question.

Time IS the evolution of state. The fact that things evolve is what allows us to define time.

In a universe without states that evolve, you cannot create a clock.

>The more I learn about theoretical physics & physicists the more I'm convinced these people are basically idiot savants.

This is an incredibly bad faith thing to say, when you admit you know nothing about the relevant field.

Physics is hard math, and has been that way for a century. Simpler mechanisms of information description are no longer accurate and unambiguous enough to clearly define what we have the data to demonstrate.

But the public gets really really mad when you tell them "Sorry, you need 8 years of math education to ride this ride" because the public is mostly convinced that math is "useless". So people with adequate training in writing to a lay audience and zero physics training keep asking physicist questions, and the answer is in math nobody will understand, so they have to approximate what math they are trying to convey or describe with some shitty analogy or words that don't actually mean the same thing. The lay public then makes all it's inferences based on broken analogies and comes to outright wrong conclusions.

This is why the lay public is still convinced quantum is magic, or allows faster than light information transmission, or magically speeds up computation, even though the math has always been clear about how that's not what is meant.

Stop thinking that vague words a physicist says are actually meaningful. They are struggling to convey difficult but crystal clear math to an audience that can barely read at a 6th grade level.

There are even "physicists" who have taken frank advantage of this system to make money by lying to the public full stop. People like Michio Kaku. Some of them are nice enough to openly label themselves "futurists", but not all.

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