Craig Callender - Setting Time Aright

To appreciate time is to touch the texture of reality. Does time differ from our common perceptions of flow and passage? Is time fixed or flexible? Do we misunderstand time? If so, how to get it right? How does time work with physics?




Craig Callender is a philosopher of science and professor of philosophy at the University of California, San Diego.


Closer to Truth, hosted by Robert Lawrence Kuhn and directed by Peter Getzels, presents the world’s greatest thinkers exploring humanity’s deepest questions. Discover fundamental issues of existence. Engage new and diverse ways of thinking. Appreciate intense debates. Share your own opinions. Seek your own answers.

[DrBrianKeating]

Fantastic to see my friend and colleague Craig on CTT!

[ministryoftruth]

When Mr Callender says "Parmenides' arrow paradox" what he means is Zeno's arrow paradox supports Parmenides' philosophy which asserts that there is no change (i.e., time).

[paulwary]

Libraries are amazing places, but their time I passing. Who will tell the history of these spaces - the yearning for knowledge, the wonder at the limitless expanse of it, the sadness when you realise your time is limited, but you still don’t know much.

[TerryBollinger]

To address adequately the issue of whether time exists, an analogy in a different topic helps. The analogy begins this way: One of the odd issues encountered when scheduling an international trip is that money can vary in value. Variable exchange rates mean that products in some countries end up cheaper for you not because their economies are inherently better than where you live but because varying exchange rates make your own money more valuable there.

I might then decide that an opportunity for easy wealth exists in this system. I _define_ my money in my local economy — my residence, to be more specific — to be at least an order of magnitude more valuable than anyone else’s. It is, after all, my residence and thus my economy, with which I can do as I please. Suddenly I am ten times richer!

Or am I? Is there a flaw in my strategy?

Never mind that for now, let’s switch to physics for a change of pace. I wish to time travel, so I use special relativity to change the orientation of my “foliation” or view of space in the universe. Accelerating to 99.5% of lightspeed, my definition of space shifts to a sharp angle, and a large swath of the future becomes part of my definition of space. In the opposite direction, a large swath of what was the past also becomes part of my space. I have freed myself of the usual constraints of time in my travels!

Or am I? Is there a flaw in my strategy?

Both examples explore the difference between local interpretations and some broader preexisting consensus. I can declare myself as rich as I want, and there’s nothing wrong with that as long as my prices apply only to my residence. However, the instant I go out into the broader world, others see what I’ve done as nothing more than a private reinterpretation of reality. Not one of the world’s economies responded to or is even aware of my change in interpretation of wealth. In principle, I could convince the rest of the world otherwise, but it would require time and resources I do not have.

Similarly, by accelerating myself to 99.5% of lightspeed, I create a new definition of space and time, but I have made only _my_ definition of space and time. It does not change the photons headed my way from the broader universe, only how I _interpret_ those photons. If I travel into the more expansive universe, others see what I’ve done as nothing more than a private reinterpretation of reality. The vast majority of the universe does not know or care about my change in interpretation of space and time. In principle, I could convince the rest of the universe otherwise, but it would require time and resources I do not have.

To put this another way, the flaw in dismissing time via block universe arguments is that they disregard Einstein’s most sacred rule: Information cannot travel faster than light. It is, alas, a bit of carelessness that even Einstein fell into since, at least implicitly and like Mach, he assumed definitions of space and time to be universal and all-encompassing.

The sadder and simpler truth is that an accelerated object _never_ overturns or even significantly impacts the universe’s consensus of cause, effect, and past historical events. Accelerating to 99.5% of light speed gives us a new interpretation of data coming in from that broader universe, but that is all it is: A different way of interpreting photons. A much cheaper way to achieve the same effect is to use computer technology to build a Poincaré symmetries simulator that takes those photons and gives us new interpretations.

It is not the existence of multiple universe-spanning definitions of space and time that prevents paradoxes. If anything, that kind of thinking is the source of many contradictions. The deeper problem is that we like to think of space as a concept that exists in isolation. That is, despite the profound insight of Minkowski had that space and time are one, we never honestly believe it. Our xyzt notation directly reflects this deeply classical bias.

Thus a star 10 lightyears away may seem only a meter away if we have the resources to accelerate to a high enough speed. However, after we cross that puny meter of distance, the star we find is 10 years older than before we crossed that meter. This aging is an example of an age gradient, an unavoidable consequence of distances measured in length and duration. The proper distance to the star was always 10 light years times 10 years. You can approach one or the other as a limit, but never both simultaneously. Such area-like distance-duration units — Lorentz areas — better capture the relativistic invariance of the universe, though they do have the amusing property of squaring traditional distance units. At a human scale, a distance of 0.3 meters — one foot — becomes 0.3 m⋅ns using Lorentz areas, but a height of a 1.5 m person becomes 25 times that, or 7.5 m⋅ns.

Is time real? Yes, very much so.

It’s also grainy, clock-based, and dependent on the binding forces of the Standard Model. It operates not on some block or multiverse but on a single universe in which change is entirely real, and the future is unavoidably unknown. Granted, it is a universe in which our human concept of length-only separations can never provide an accurate description. Our neural systems are optimized to make maximum use of the lovely stabilities that exist in our local solar and planetary-surface environments. These stabilities, in turn, create the illusion of purely space-like separations extremely useful for survival.

A new path is needed. Treating time as a mystically smooth math-only continuum adds only noise that confuses the details of how Standard Model matter creates it in nature.

[2023-01-02.17.45 EST Mon]

[brothermine]

It's nice to hear someone like Craig point out how wrong-headed are the subset of physicists who assert that entropy is more fundamental than time and explains the ”arrow” of time. Entropy is measured by counting equivalent microstates, and tends to increase due to a statistical property of (pseudo)random interactions between components of the microstates. Entropy cannot be fundamental.

[TerryBollinger]

The concept of stationary solutions to Schrödinger's equation contains a subtle but essential twist: Composing stationary solutions from _linear_ momentum components requires occasional ("particle in a box") or continual (orbitals) replacement with new, differently oriented momentum components.

This process of momentum function replacement requires briefly confining the momentum vector within a local approximation of what, at classical scales, we call xyz space. For example, when a sun photon radiating out in all directions encounters a NASA solar sail, it becomes, at that moment, vastly more localized in xyz space than before its reflection, despite never being absorbed by any specific particle in the sail. The photon and solar sail share and record a brief and remarkably private exchange in which both say, we are here.

An ordinary stationary wave function is a paradox standing openly in front of us. It is a collection of linear momentum waves that self-confine and begin anew in a small, private xyz space each time an internal energy potential redirects them.

Such minute sharings of agreement on mutual locations are essential to time because the mystery of time begins with the mystery of its perpendicular coordinate set — the xyz-like ability of two or more entities to say, Who-like, "We are here! We are here!" A proton and the electron remain bound and known to each other in their own local space by continually finding, binding, and redirecting each other's linear momenta, a process better known as acceleration.

And here's a surprise: This process of self-confinement by acceleration is identical to the "mystery" of wave collapse. Far from depending on some distant or omniscient observer, wave collapse begins with the tiniest of entities grasping each other like desperate lovers in the middle of a terrible storm of uncertainty. Like fish in water, we fail to see ordinary mutual acceleration as wave collapse because it is the essence of the always-localized classical world from which our ability to wonder about such things takes place.

Defining a location in space is the first and most fundamental step in defining time's direction. That's because wave function change confined within a tiny, fragmentary bit of xyz space becomes something new: The earliest tickings of a repeating clock. That ticking provides the only experimentally meaningful definition of the forward motion of time.

A warning: Due to at least a century of casual and deep-set acceptance of the continuum school of mathematical interpretation of all experimental physics, the following thought experiment can be tricky for some. Forget the intellectually fascinating but experimentally uninterpretable concept of "Planck" space. Ask a different question: In the case of hands-on, experimentally accessible physics, what is the tiniest physically meaningful event in which the ever-spreading momentum waves of Schrödinger's equation become localized in xyz space?

There is no need to descend into the mathematical chaos of energy-indifferent and (folks forget this) necessarily aether-like Planck foams. A far more straightforward and physically meaningful answer resides in the examples I've discussed: Whenever there is a binding force that redirects and thus relocalizes linear momentum components, both a bit of confining and thus cycle-enabling xyz space and thus also a fuzzy vector of time emerge naturally.

Such bottom-up units of time begin small and stay quantum-fuzzy with small particle counts. The emerging orthogonality between space and time sharpens quickly in multi-part, multi-scale bound systems that cancel those forces internally and thus no longer experience momentum changes as a whole. That lack of changes in linear momentum allows time vectors that were at first fuzzy and indistinct to consolidate into sharp, classical-scale definitions of time in which the bound systems at multiple scales need only follow the acceleration-free geodesics of general relativity to define their time vectors.

The critical point is that one can experimentally decipher time physics only with clocks. The dependence of clocks on acceleration and binding means, in turn, that one can only solve the nature of time by including the binding forces and potentials of ordinary matter and the Standard Model. The converse approach of assuming spacetime to be some perfect mathematical fabric that exists independently of the physical constraints of matter and energy is just sloppy thinking. It doesn't matter if such sloppy thinking has been popular for decades or centuries. To understand space and time better, all that is needed is to get back to what physics tells us in experiments. It cannot be determined by inherently noisy and, thus, deceptive elaborations of equations that long ago lost their connections to actual physics.

[2023-01-02.01.00 Mon]

[rc]

there's no better time to discuss time than the first day of the year :)

time variability between two isolated systems could be possible only if their fundamental laws were different... if both systems shared the same 'building blocks' but not their complexity/size then a difference in the rate of change in parts of one system could be just the result of higher complexity and not necessarily by 'slowing of time' 🤔

[Novastar.SaberCombat]

Reflection is key in a world which contains nearly none. Unfortunately, most of humanity cannot see beyond the physical version of it. Yet the other three mirrors (mental, psychological, and spiritual) are of far greater importance for all individuals to confront.

"Before I start, I must see my end. Destination known, my mind's journey now begins. Upon my chariot, heart and soul's fate revealed. In Time, all points converge: hope's strength, resteeled. But to earn final peace at the Universe's endless refrain, we must see all in nothingness... before we start again."
🐲✨🐲✨🐲✨

--Diamond Dragons (series)

[ItsRomanDrobot]

A guy named calendar talking about time. Beautiful.

[MrDooDitty]

I think infinity is an elusive reference for those that are interested in ratios that quickly become negligible and has limited application except for scientific theories at this point. Insignificant odds of possibilities can generally be ruled out after a certain point.
Obviously time is related to change and movement. Infinity might create a sense of timelessness where time must always exist even at the slowest calculable rates.
It’s possible to compare infinity to an unbreakable rubber band where motion reverts in the opposite direction but may also define the limits of energy distribution to a point of zero motion and can signify an actual endpoint.
A complete equilibrium of all matter would make use of an infinite scale of force and distance where time stands still.
Personally I believe energy is directional until it rebounds from forces pulling everything back together only to expand again.
Therefore I suggest time is infinite but the rate of change is constantly speeding up and slowing down then repeating over and over again.
Of course this requires a closed system and obviously we have not the slightest idea of all that exists and random change can obviously keep things moving and time to tick for as long as the imagination can conceive of the possibilities.
There will be a lot we will learn but so much more we can never truly know unless we could know of everything everywhere all at a single moment.
Maybe we will learn that this is a simulation with adjusted limitations that are all that’s needed to perceive what’s real only to realize it’s only designed to support the needs of what the programming is designed to do.
The programmer can always add some detail if we get bored but we are a long ways from that at this point.

To what end is what we must ask ourselves constantly or we might waste the TIME we have

[thickdickwad]

Pretty good video! I like the interview / conversation style format 😊

[rhcpmorley]

Robert, how many times can I explain this to you!!! Time is profoundly simple!! It staggers me that scientists (and philosophers) are surrounded by ubiquitous evidence in front of their eyes, yet still can't grasp this profoundly simple concept. And you know they can't or don't.
We think we perceive time passing, we think we experience time passing...but in fact we see change happening and experience change happening. Look around you!
The ONLY evidence of Time passing is quintillions of change-events (quantum and compound change) happening, all around and within us. This evidence is undeniable...the universe expanding, planets spinning, tides turning, life breathing, clocks ticking, atoms vibrating, quarks decaying, protons flashing. Change, change, change. All change happens due to energy differential. Nothing to do with time. Time does nothing.
Time is demonstrably (and undeniably too) merely the way we reference change and change-events in 2 distinct contexts:
1. The collective 'flow' of change - Time is to Change what Traffic is to vehicles, a non-specific collective noun. 'Time passing' actually refers to a (non-specific) set of change events happening.
2. The dimension of change (the calibration of change-rate (miles per hour) and the indexation of dates change events (e.g. time of day, and dates).
As I say, profoundly simple and ubiquitous evidence all around you. Dimensions and collective nouns are ABSTRACT nouns. I say abstract, Einstein suggested illusion (he was slightly mistaken)....but both mean 'not real'.
And Change-events (and hence Time) are, by definition, reference-frame (e.g. quantum) specific; as opposed to the notion of some universal absolute Time 'thing', for which there is no evidence.
So Time is abstract, there is no absolute, universal, singular time 'thing'....if there was, we'd have found it by now.
Think quantum change. Change (i.e. the outcome of energy differential) is the underlying fundamental reality. It's really simple. Open your eyes.

[stephenzhao]

2:31 CC: he came up with this really bizarre solution to Einstein's equations through which you have possible time travel paths through every single point and in that space time you can't even find a singule now at all, there's not even a single spatial slice that extends everywhere and he thought: well if the laws of physics allowed that then and there's clearly no time in that and the laws allow no time and so there's no time you thought. 3:21 Bob: well, just define each one, well, general relativity says what about time? CC: General relativity says that time uh you know the ticking of the clock is local to you, and it uh depends on the matter distribution so it could help how you know how those ticks happen depend on you whether know you're near a planet or not. Quantum mechanic says, "No! No! No! It's just more like classical physics that's got you know this distinguished it's distinguished parameter." ❤👍✌Bob: The time is a fundamental background in which everything else plays out. CC: that's right. 3:58 and so you're trying to marry these two together and the clash on time and so one option is just to get rid of it. Now that's getting rid of it and getting rid of it there's gettting rid of it, and not explaining the motion that we see which would clearly not be it will not be good science and there's getting rid of it and still of explaining things and so that's what I think is interesting about some appraoches in quantum gravity where you could have an idea a fundamentally timeless world what I mean by that is uh that there's nothing you would dub nothing worth calling time there, but you could still precicely say if I say to you Robert if I say 👍 time is that with respect to which the meta fields evolve uh I could still find in that system of correlations with no time I could find regimes where the manner fields end up looking like they evolve according to time uh now we can call it and we call that ting time. and so then we could say that even though that fundamentally there's no time but that in a certain regime something that becomes worth calling time. 5:10 👍 Bob: well if you have something that changes or some relationship between the two in this change isn't that time isn't that one definition of time? CC: Yeah I think that's right. (but it's a narrow addition) So ... it's narrow but if it explains what we see and so if it's explaining the relationship you know my hand moving back and forth closer and further away from you, well isn't that enough? 👍Bob: I don't know whether it's enough that's the frustration because we have this integrated feeling of time and now by disaggreagating it and saying this piece may not work at all this piece may work partially this piece may work you know we have a different conception ❤ is it possible that what happens on the micro level is 5:52 is sufficiently different than what we perceive that it's a difference of scale as opposed to a difference in kind? CC: Yeah I think, maybe that's a good way to put it because uh yeah so we're used to the idea that you know the micro level might have very different properties than the macro level so we you know see objects as colored but we don't think atoms and photons are red or blue (right) now we're looking at this of the ultimate in disagreement between levels so we're saying even time uh isn't uh emerges from one level to the other. But I think that's right it would be more of a question of degree because some things may be you know in certain regines (e.g. if a huge 3d-object, assuming another universe, moves faster than light speed or even dark speed, 3x10^34 m/s ≤ DS < ∞, it's become a string to the observer, accordingly. Therefore, it's so reasonable that Roger Penrose's aeon might be Metaverse The Original) things may become behave more and more time like until eventually you say aha that it is behaving just the way like if it looks like time walks like time it's time (in theological term we call it Archagel). Blessings in 2023 the New Year.

[Jack-rvb]

Lines of longitude determine time but all meet at the same point at the north and south pole, so what time is it at the north and south poles ??

[anonsurfer]

Time seems to be a consequence of an incomplete comprehension of the universe or multiverse. It again comes down to the definition of the word nothing which is what is being debated in physics. If you believe there can be no such thing as a true nothing (like the number 0 not being a standalone number but always manifesting as various numbers of opposite signs to remain in equilibrium, i.e., having activity going on inside it), then time is illusory and relative.
If the 0 manifests as a +1 and a -1 or as an infinite series of numbers/things (matter, anti-matter), then nothing has changed from the zero's vantage point and as such no time has passed.
Particles, objects, attributes, emotions, etc. are all balanced by their opposite properties and exist simultaneously in the multiverse. Any notion of time is relative to the individual because it sees itself in a fragmented manner, not being able to comprehend the whole.

[keithmanfredi]

Time really seems like an emergent property of changing field states. I imagine the only reason it feels so real for us is because of how much 'regular field activity' we have in our lives.

[joaoferreira]

So, this gentleman's name is "Callender".

[jamesruscheinski]

could be both relativity time and quantum time? time transitions from quantum to classical with measurement?

[reason]

I agree with Craig that scientists can get very confused. If anything is fundamental at all to scientists, its that math is fundamental. This leads to conclusions that are clearly incorrect. Math is not perfect, and math is not complete. For instance, scientists have to ignore their infinities with renormalization. Math is NOT fundamental. It's just a language that humans use to try to describe things.

[-by-_Publishing_LLC]

Time owns its origin from mathematics. It's true that the mathematical equation (1 + 1 = 2) requires *zero time* to execute, but the precursors for time are still embedded within the equation. This equation reads, _"When I add one to another one, I end up with twice as many than I had before"._

*"When I add ..."* - represents the present.
*"to another one ..."* - represents the future.
*"... than I had before."* - represents the past

Once mathematics is forced into multidimensionality (Big Bang), matter replaces the abstract symbology of mathematics (terms), and what we call "time" becomes the operators that separate the expressions. The past (sum) becomes every physical interaction taking place since T=0.