One. Welcome to Nontrivial. I'm your host, Sean mcclure. In this episode, we'll take a look at the nature of time. We try to figure out what it is and what these physics can and cannot tell us whether or not it's an illusion and how memory and consciousness might play a fundamental role in the realization of time. I'll discuss Einstein's relativity. I'll review a thought experiment that suggests time doesn't exist.
Another thought experiment that uses the phenomenon of quantum entanglement to try and explain the perception of time. And I'll describe what I think is wrong with the current physics approaches to explaining what time is and offer some ideas. At the end, I'm Sean mcclure and you're listening to Nontrivial. So, a book I read this week is called In Search Of Time, the History Physics and Philosophy of Time by Dan Falk, In Search Of Time by Dan Falk. It's a pretty good read.
Um Talks about a lot of things related to time, obviously, uh you know, the perception of time in humans, uh the role that time has played in society and civilization throughout history.
Uh He goes through some of the historical monuments that civilizations have put together that, you know, either kind of align themselves with the rising sun or the constellations or something that's going on, you know, up in the sky and, and how that may have been used as calendars and, you know, may have played a role in helping, you know, humanity, you know, time things for agriculture and things like that.
Uh And then looking at how we kind of broke away from that or definitely broke away from that notion of celestial time when we started to create our own clocks, right? So we kind of mechanized, our notion of time, created our own clocks and basically pursued uh you know, greater and greater precision around measuring time when you get into things like atomic clocks.
And that whole story there, uh it goes a little bit into, you know, Einstein and, and how, you know, he brought us the notion that there is no absolute time and kind of leading up to this, this realization that time may be nothing more than an illusion when you really kind of look at what physics can and cannot explain. And then, you know, our perception of time and the arrow of time and what that might mean.
So, uh you know, go ahead and check that book out if you want in search of time by Dan Fox. So what does this make me think about? Well, let's talk about time, right? We all look at our clocks on a fairly regular basis. Right. We usually, uh, you know, usually it's the ones on our smartphones. Many of us have deadlines, either self inflicted or those given to us by, you know, a boss or business partner. We drop kids off, we pick them up.
You know, we, we meet people for dinner, we exercise for a given amount of time. You know, time really seems to run our lives, uh, or at least provides the constant backdrop by which the events in our lives play out. We value time perhaps more than anything else, right? Time is more precious than things more valuable than money. Time is the thing we cannot get back. Time is everything. Well, while we perceive time as the ticking by of moments, current science cannot tell us what time is.
OK. Science can explain matter, motion, energy and force as we know. Uh and those all of course work together to produce events that we see happen and these are assumed to occur, these events against a backdrop of space and time. But the concept of time itself is ill defined, right? Since it turns out that there is nothing in physics that truly requires time.
In other words, the mathematics of physics work perfectly fine by either ignoring time altogether or assuming they work just as well going forward as backwards. Science cannot answer the question regarding whether time is an absolute thing or something that is a mere perception of humans untethered to anything real or physical. Well, Einstein really put the nail in the coffin, right?
When it comes to thinking of time in an absolute sense, his special theory of relativity showed that there is no such thing as absolute time, which means we cannot point our finger at the concept and say that is time. More specifically, Einstein showed that two people can disagree on what now means as in they can disagree as to whether two events happened at the same time.
So to understand this, we can look to Einstein's famous train and platform thought experiment that Einstein used to make headway with special relativity. Thought experiments take us where current scientific experiments cannot right. The train and platform thought experiment shows us the important concept called relativity of simultaneity, relativity of simultaneity.
So imagine a box car moving along a train track with a man standing in the center of the box car as it moves the man standing in the center flashes a light and sees the light hit the back of the box car and at the front of the box car at the same time, I guess using his peripheral vision or whatever. So now imagine someone standing instead on the train platform watching the box car go by.
He observes the same event, he sees the man in the middle of the boxcar flash light with light hitting the back in front of the box car walls. But the man on the platform does not see the light hit the back of the box car at the same time as the light hitting the front of the box car.
This is because according to the man on the platform, the back of the box car is rushing towards the light beam, making the back of the box car hit the light before the light hits the front of the box car which is moving away from the light beam. Of course, we cannot notice, we can't notice things like this. Uh you know, in our everyday experience because it moves, you know, too quickly, right? For us to see the difference.
But as a thought experiment, the logic holds two different observers would see different things based on our known laws of physics. Both men are witnessing the exact same two events, light hitting back wall, light hitting front wall, but their different frames of reference, so to speak, make them disagree on whether the events are simultaneous. The man in the boxcar believes they are simultaneous while the man on the platform believes they are not.
So one of the crazy truths to come out of special relativity is that neither the man in the box card nor the man on the platform are wrong. They are both correct. This means that what constitutes now in time depends on the observer time itself, depends on the speed at which someone is moving relative to the events. They are witnessing. In other words, time is not absolute time is malleable time is relative and this is an astounding realization, right?
I mean, again, think about the role time plays in our lives. We invoke time, any time we make a measurement, every experience we have is a lot of a place in our minds is having happened at a certain time. Time has an intimate connection to space itself. At different times, things appear at different points in space if they're moving.
So if we look at the two core pillars of physics, quantum mechanics and relativity, we see that they can actually disagree on the role of time, quantum mechanics assumes time is uniform. Well relativity shows us that time is relative. So quantum mechanics is actually using the intuitive sense that we have about time, that it's something that ticks by in his uniform. Whereas relativity sees time as something that requires context to define as per Einstein's thought experiment.
We just looked at quantum mechanics and relativity have so far been immune to our efforts to combine them into a coherent unified theory, right, when we attempt to mix quantum mechanics with relativity, for reasons of you know, trying to quantize gravity as they say, we get equations that suggest the universe is static as in nothing happens as in time doesn't exist in 1967 theoretical physicist John Archibald Wheeler and Bryce Dewitt mathematically combined the ideas of quantum mechanics and general relativity.
A step towards the theory of quantum gravity. And this led to what we now call the Wheeler Dewitt equation. They did so successfully. But with one catch, their results showed that there is no such thing as time. So this is known as the problem of time if time is not absolute as per special relativity, and it isn't appearing in the equations that reconcile quantum mechanics with relativity. Then perhaps time is not fundamental to reality. At least physicists would say time is not fundamental.
But I take issue with their use of the word quote unquote fundamental as I'll explain in a bit. But the important point here is that the two core theories of physics can only be thought are brought rather together mathematically if we assume time does not exist, which of course makes no sense. I mean, we know time exists or do we what if time is nothing more than an illusion? I mean, we obviously perceive time, we go through life noticing how things change.
We know we were once young, then older, we know that we will someday die if time truly is nothing more than an illusion, something that does not exist beyond our perception. This is a fascinating thing to consider. I mean, after all, what would this say about our reality? This means we must step away from the limitations of current science and think about time at a more philosophical level physics as we know works by stripping things down to their bare bones, right?
It reverse engineer nature, looking to uncover what it considers to be quote unquote fundamental aspects of a given phenomenon for something to be considered fundamental in physics. It means a basic elementary concept that is essential for framing the kinds of problems we wish to solve. Basic means we cannot strip much else away. It has a kind of self contained definition. Physics is preoccupied with things like really small particles and forces for this very reason.
The idea that something fundamental exists at deeper physical levels is largely how we are taught to think about nature. And in one sense, it does seem intuitive that the more layers we pull back the more primary role whatever we find is playing. But assuming things are that are fundamental only occur at the bottom is problematic. I mean, I've talked about this before.
There is a what I like to call great disconnect between the pieces that make up a system and the actual phenomenon that we experience reductionism has proven to fall, you know, pretty short and dramatic fashion, right? And yet its convenience keeps all sciences held to its allure. I argue that physics may be failing to explain time for the same reason, it fails to explain reasonably complex phenomena.
Physics thinks that that which is fundamental exists at the bottom after stripping everything away, but that's not complexity. And when it comes to explaining time, this may be problematic because one all attempts to find explained time at the so-called fundamental level have failed. And two, as we will see, there's mounting evidence that suggests time may be an emergent phenomenon which obviously goes directly against a reductionist explanation of time as I would argue.
So let's go back to this idea of emergence here. So for something to be emergent, it must arise out of the interaction of multiple pieces, right properties of that which emerge uh uh of that which emerges does not appear in the smaller parts that went into the system. Looking across the branches of physics, you got particle physics, classical mechanics, thermodynamics and statistical mechanics.
You have electromagnetism and photonics, relativistic uh mechanics, quantum mechanics, atomic physics, molecular physics, optics, acoustics, high energy, nuclear, all this kind of stuff. They all take a very reductionist approach to explain what is happening. They all attempt to boil down the phenomenon to its core pieces and consider those pieces to be a more fundamental aspect of reality, quote unquote fundamental.
Perhaps the only exception is physic in physics would be say condensed matter physics which at least acknowledges phenomena that are complex in nature and makes an attempt to model them more appropriately. Although I think the allure of reductionism remains a constant temptation here as well. But look reductionism has worked exceedingly well for physics because physics by and large is not interested in genuinely complex things.
Physics is almost entirely about simple systems, physics strips away complexities as part of its approach. But when it comes to time, this approach may not be appropriate. Now, I say may not be appropriate because we don't know if time is indeed an aggregate level phenomenon or something that exists at the smaller scale. We don't really know if it is emergent, right? But what I am saying is that one, the usual methods of physics don't account for aggregate level phenomena very well.
I would argue and two, there's mounting evidence that time may in fact be something that emerges. And so I argue that physics may be failing to explain time. For the same reason, it fails to explain many other things. Current physics does not have the toolbox to tackle true emergence. Uh I'll make a quick aside here because I'm saying quote unquote true emergence. Like what do I mean by this?
Well, some people like to differentiate between so-called, weak emergence and strong emergence, weak emergence or would be things like density pressure, temperature, you know the things that are emergent but can still somewhat be connected to a low level attic. If you will understanding of reality methods like renormalization can kind of use the averages of many particles to calculate the values for things like density pressure and temperature.
But density pressure on temperature are barely the beginnings of what I would call true emergence or what some might call strong emergence. I argue that strong emergence is what leads to the overwhelming number of phenomena that we experience.
Thus, I'm not crazy about the demarcation between so-called weak and strong emergence and think appealing to weak emergence as an example of a connection between being made between the micro and the macro is really just a kind of crutch physicists use to justify reductionist methods. But anyway, let's get back.
So just know that when I'm talking about emergence, I mean true or strong emergence, right, that which only appears when many, many pieces come together to produce a truly aggregate level phenomenon that cannot possibly be explained by appealing causally to the lower level. So I kind of take issue right, with how physics considers something to be quote unquote fundamental only if it exists at the bottom.
Meaning only after removing all the supposedly super uh superfluous complexities, do we actually expose something that shows us what a thing really is? I don't agree with that, you know, as though showing what exists after the removal of so many externalities helps us to better define a thing. And I remember I talked about this issue in my episode called Shifting Up. How victors let nature coordinate the wind, right?
Defining something in terms of its core components is an awful way to define a thing because context is everything reverse engineering a thing you know, to to reach its true definition is a vestigial aspect of the enlightenment. I would say that is rapidly losing relevance in today's scientific and engineering paradigm.
It's like a, a small remnant of something that was once much more uh you know, consistent with the way that we thought of nature and, and the way that we engineered simple systems. So defining something by its pieces only makes sense when those small pieces drive what we measure and experience, which is not the case for the overwhelming number of phenomena in the real world.
What drives what we measure and experience are things that precipitate out after many, many pieces come together to produce the outputs. So when it comes to considering time, which all of us feel is something fundamental because you know, it's everywhere and plays such a significant role in our lives. Framing quote unquote fundamental is the only as something that only exists at deeper levels I would say is problematic. And I think it makes us look for time in all the wrong places.
So if we're going to think about what time is and and bring forth a new scientific approach that incorporates time that we're going to have to look in a place where it is more likely to be. And as we will see, that seems to be in the realm of things that arise via the interaction of pieces, not the pieces themselves. Now, at the beginning, I mentioned the quote unquote problem of time.
This is where all attempts to reconcile quantum mechanics and relativity only work at the mathematical level, if we pretend time doesn't exist, which nobody realistically wants to do. Again. The Wheeler to wit equation which successfully combines the theories of quantum mechanics and relativity into a unified theory of quantum gravity does. So at the cost of giving up time altogether, which is unacceptable.
So the Wheeler to wit equation is not actually a solution to quantum gravity, we cannot ignore time. But there is an approach that hints at a solution. The attempt to resolve the problem of time that arose from the failure of the Wheeler Doit equation might come from the quantum mechanical phenomenon known as entanglement quantum entanglement, which many of you have probably heard before happens when two or more particles become correlated with each other.
So that they behave as if they were a single particle quantum entanglement leads to the extremely counterintuitive result. We're observing a property of on one particle. Let's like say it's spin immediately allows the property of the other particle to manifest no matter how far apart they are. So for example, say we have a subatomic particle and it decays as subatomic particles often do into an entangled pair of other particles.
We can call these other particles that shoot off after the decay daughter particles right daughter particles which move in opposite directions. Now the decay event will obey the various conservation laws. And as a result, the measurement outcomes of one daughter particle must be highly correlated with the measurement outcomes of the other data particle.
In other words, things like total momenta and angular momenta and energy that were in the parent particle are expected to remain the same before and after the separation into dotted particles. OK. So imagine taking a chocolate chip cookie and it has 10 chips on it and you split it in half. Now each half has five chips assuming a pretty uniform ship arrangement, right?
But the total number of chocolate chips remain the same right, regardless how far apart we separate the halves and nobody has taken a bite yet. It's the same idea superficially anyway, with the daughter particles of the decay process, for instance, a spin zero particle could decay into a pair of spin one half particles.
Now, since the total spin before and after this decay must be zero as per conservation of angular momentum, whenever the first particle is measured to be spin up on some axis, the other when measured on the same axis is always found to be spinned down. If the first particle is measured to be spinned down, then the other must be spin up. So with quantum entanglement, it doesn't matter if the particles are right next to each other or Galaxies apart.
The effect of both particles realizing their properties occurs instantly regardless of the distance between them. Now actually, this doesn't appear that counterintuitive on its face because I mean think about it with a chocolate chip cookie example, there were 10 chips in the cookie to begin with. Right.
So splitting them into two pieces and then sending them to different Galaxies and then having someone measure that there were five chips on one half would immediately mean that there are five chips on the other. If they measure, if they measure three chips in one half, then the other must have seven. So that's not, you know, there's no magic here, right? It's just a fully deterministic aspect of a reality that if we split a hole into parts, those parts still sum to the hole at the beginning.
The problem with the chocolate chip analogy is that quantum mechanics doesn't really work like this. Whereas cookies and their chocolate chips appear to have definite locations and properties, subatomic particles have a smeared out existence. If you will, they don't really have a location or definite properties.
Rather they occupy all possible locations and values at once and only once they are observed by someone does their existence come into focus as in their location and properties become realized. Now, this is one of the crazy truths revealed through quantum mechanics, right? The existence is of fundamental particles, they're not located anywhere specific or have any definite values to the properties until the measurement is made.
So whereas asking someone a galaxy way how many chocolate chips are on their half cookie and then knowing immediately that the other half must have the remaining number of chips is hardly mysterious. Having the same effect occurring in a quantum mechanical system would be extremely surprising. Right, quantum mechanical things don't start with quote unquote 10 chocolate chips, so to speak, because they don't really start with anything.
Their values are not determined until the measurement is made. Which means there was a kind of quote unquote spooky action at a distance to use the phrase out by Einstein when he realized how crazy and counterintuitive this result was. So there seems to be instantaneous communication between the two particles, right? I mean, how else could one explain the immediate realization of both daughter particle values?
Again, someone measures their property, let's say spin up and then instantaneously you know that the other one must be spinned down even though it's got this smeared out kind of undetermined existence, right? But it's not communication between the particles that's happening since that would violate the fact that nothing can move faster than the speed of light, which we know from Einstein's theory of relativity, right? It can't be the case, right? Nothing moves faster than the speed of light.
But if it's not communication, then what is it, what's happening when things happen instantaneously like that with quantum entanglement? Well, normally when we want to describe a particle in quantum mechanics, we use what's called a wave function. A wave function is just a mathematical description of the particle one that specifies the quantum state of an isolated quantum system.
So think of the wave function as giving the probabilities for the possible results of measurements made on the system. More specifically that can be derived from the wave function. But that doesn't matter. The physical interpretation of a wave function would thus be a kind of smeared out existence where a particle can be in a so-called superposition of all possible states.
But when someone goes to measure something about the particle like a spin, the wave function quote unquote collapses and the particle realizes its value. So when two particles are entangled like our daughter daughter particles after the decay process, it turns out they share the same wave function.
This means that when someone measures one of the data particles, the entire wave function collapses and both particles, uh both particle values are then realized right now, Einstein was not a fan of of, you know, this notion that two particles could realize their properties instantaneously regardless of how far apart they were. This goes against the principle of locality which states that an object is influenced only by its immediate surroundings, which makes intuitive sense, right?
This is why Einstein along with Boris Podolski and Nathan Rosen wrote a paper called can quantum mechanical description of physical reality be considered complete where they argued that the only reason we see things like quantum entanglement is because we cannot see some underlying more fundamental aspect of reality at play. Specifically Einstein Podolski and Rosen argued that there must be some quote unquote hidden variables. And that reality does indeed obey the principle of locality.
So there's something we just can't see. I mean, this is basically saying that the only reason we need to use probabilities in quantum mechanics is because we don't have access to the underlying reality at the most fundamental level. And I mean, that makes sense. I mean, probability is usually used to deal with phenomena that are indeterminant. It's a tool to help us grasp things that are not exactly known established or defined.
But the most accepted interpretation of quantum mechanics is that the probabilities that are used are not a crutch for a deeper reality rather reality is itself probabilistic. There's nothing deeper than those probabilities that is how nature is constructed. This is called the Copenhagen interpretation for historical reasons that we won't get into.
But while the verdict is still out on the correct interpretation of quantum mechanics, experimental results appear to agree with the notion that quantum phenomena are in fact probabilistic in nature and that there are no hidden variables that would restore the idea of locality to particles. Now that you know the technical details relate to something called Bell's theorem whose results show that quantum mechanics is incompatible with local hidden variable theories.
Given some basic assumptions about the nature of measurement. Bell actually wrote a paper called on the Einstein Podolski Rosen paradox, which is obviously in response to the paper by Einstein and Friends Bell showed that if measurements are performed independently on the two separated particles of an entangled pair, then the assumption that the outcomes depend upon hidden variables would imply a mathematical constraint on how the outcomes of the two measurements are correlated.
This constraint is something we now call the Bell inequality. Bell showed that quantum physics predicts correlations that violate this inequality. And so the only way hidden variables can explain the predictions of quantum physics is if they were or are nonlocal right. And that means that somehow the two particles were able to be realized instantaneously no matter how widely the two particles are separated.
So anyway, in other words, according to all predictions, to date that use quantum mechanics reality appears to be indeed nonlocal. And the phenomenon of quantum entanglement does indeed allow for the properties of particles to be determined instantaneously across large distances.
In fact, this is a timely conversation because this year's Nobel Prize in physics was awarded to Alan Aspect John Clauser and Anton Zeller, all of whom carried out experiments over several decades related to the phenomenon of quantum entanglement. The test that aspect closer. And Zeller did show that Bell's inequality is violated.
And that means that a local explanation with hidden variables as though there's something you know beneath the probabilities is only possible if measurement independence is violated. This means that there is a way to have a local explanation of the observations associated with the quantum entanglement one that would not entail a so-called spooky action at a distance. And that would be if measurement independence is violated. OK. So stick with me a lot of jargon.
So far, I pro I promise I'm gonna bring this back to time even if you kind of get lost here. I promise this will all become conceptual. OK. One more thing. So measurement independence means the person doing the measurement has free will to choose the measurement they want to make. Right? I mean that makes sense. I assume that if I go to make a measurement that I have the free will to do so or not, the choice is mine.
But there is a theory called super determinism which suggests that the predetermined steak goes all the way back to the Big Bang or whatever you think the beginning is, which is another way of saying that all of our choices were predetermined from the beginning. This would make everything local just like the cookie having 10 chip, 10 chips to begin with, right?
This could thus explain how there is indeed a local theory and measuring something merely confirms the one half just like we did with the cookie. Now to be clear, there is no evidence of super determinism that doesn't mean there won't someday be evidence for that. But the implications of that would go well beyond providing a local theory for quantum mechanics, it would actually suggest that free will itself doesn't exist.
It says that human experimentalists are not free to choose which measurement to perform. So anyway, that's quantum entanglement and uh you know, apologies to people got a bit lost. So I'm gonna bring it back to time now and hopefully this will uh kind of all wrap up makes sense. So don't worry too much about those details.
But now that we have settled quantum mechanics, just think, you know, you have a particle, it decays two daughter daughter particles go off and no matter how far apart they are, if you measure one of them, you immediately know the result of the other or the other one gets realized. And it's not because of a communication and it's not because they were determined before they separated because nothing was determined before they separated. Right.
Again, there's that wave function, it's that smeared out existence. It actually happens instantaneously because those two particles share what we call a wave function. And only once the measurement is made that wave function collapses. And so you have this instantaneous realization and these things could be, you know, thousands of light years apart, they could be Galaxies apart and it would instantaneously happen. It's not a communication, nothing is traveling faster than the speed of light.
It's because of this smeared out wave function all of a sudden collapses. And then everything gets realized. OK. So that's quantum entanglement now to understand the connection between quantum entanglement and time because that's what we're here to talk about. We first have to think of time as being something we notice based on things changing. Now, this makes sense if I notice an ice cube melt, this corresponds to a perception of the passage of time, right?
The ice cube used to be solid, but now it's liquid, uh an egg becomes fried, a cup breaks into small pieces. So noticing how things change is a way to think of time. Now, the usual connection made between physics and time when using the concept of change is entropy. I've talked a lot about entropy in other episodes under various contexts. Entropy is a scientific concept that is most commonly associated with the state of disorder or randomness, right.
The second law of thermodynamics tells us that things tend towards disorder due to an increase in entropy. Entropy is a way of explaining the so-called arrow of time where we perceive time to only move forward because entropy is framed as having a single direction since it never decreases in closed systems, fried eggs don't become raw eggs, broken cups don't reassemble themselves. So noticing change is a way to frame the perception of time and entropy is the usual way to do this.
But entropy doesn't offer a complete explanation of time for reasons I'll get into later. Like many other explanations of time. It is woefully lacking in explanatory power. Another way to use the idea of things changing as time is to instead think of the change that's observed that is observed by someone doing a measurement on entangled particles. OK. So this is the connection. Now the big blabbing I was doing about quantum entanglement. I'm gonna connect this to time now.
OK. So another way to think about change is the change that you observe when someone does a measurement on an entangled particle. So going back to our quantum entanglement example, we know that measuring one of the two daughter particles that split off from the decay event makes both particles realize their values like spin up or spin down. Now, in 1983 the theorist Don page theorists Don page and William Wooters, they came up with a way to explain time based on quantum entanglement.
The premise rests on the idea that the way a pair of entangled particles evolve as a kind of clock and that clock can be used to measure change. But importantly, the results depend on how the observation is made. Pa And Wooters used a thought experiment to show how quantum entanglement might explain time. Similar to how Einstein used a thought experiment to showcase the consequences of the relativity of simultaneous uh simultaneity. Right.
So thought experiments uh tend to be pretty useful now uh to theorists anyways. So the thought experiment involves someone who is inside the universe and a godlike observer outside the universe inside the universe is where we run the kind of quantum entanglement experiments I explained previously where we measure the spin of a daughter particle as spin up and then know the other particle must be spinned down.
This means that in order for us to notice change such as the other particle taking on the value of spin down requires that we make a measurement. This is another way of saying that we have to be the observer inside the universe because observing is uh you know the same as making a measurement in this context, right? It's as though someone living inside the universe is always making measurements because we are constantly observing.
So according to the Copenhagen interpretation of quantum mechanics, we know that making the observation is required for these kinds of entanglement changes to take place. Recall the wave function collapsing, right? OK. Now there's another observer imagine a godlike observer outside the universe. They are not making measurements on any particles, they are just observing the universe as a whole.
Since they are not making any specific measurements, they are not seeing the particles change, they will see a static universe as though nothing is happening.
This has actually been shown experimentally believe it or not by a researcher, uh Aria Marva and others at the Italian National Institute of uh Metrology Research, the Inrim in Turin Italy, where they performed the first experiment to test of page and water's thought experiment in a paper titled Time from Quantum entanglement and experimental illustration illustration. Sorry uh this was published in 2013.
The team's results supposedly confirm that time is indeed an emergent phenomenon but only for internal observers. While for external observers, the universe appears static. So what does this mean? Well, the researchers created uh a toy universe if you will, that includes a pair of entangled photons and then two different kinds of observers. The entangled photons both have a polarization that can be changed by passing the photons through a birefringent plate.
Don't worry too much about what that plate is. They just know that it will have a, you know, essentially an effect on the photon to change it, right. So in one set up the internal observer measures the polarization of one photon and then compares this with the polarization of the other photon. The difference between the two measurements is a measure of time. Again, think of, you know, time is essentially being changed right.
In the second set up the photons both pass through the birefringent plates just as before. But this time, the observer only measures the global properties of the photons and compares these properties to a clock that is independent of the universe. In other words, this second setup is supposed to be the external observer. It turns out that in this case, the observer cannot detect any differences between the photons. No difference means nothing is happening in the universe.
The universe appears static to this external observer time does not emerge. The page what is thought experiment has thus been verified experimentally at least, you know, according to some physicists right, quantum entanglement is thus a possible explanation of the illusion of time since only the observer that is inside the universe is making the measurement, meaning they would be the one that notices when the measure particles are changing.
Since this is when the wave function collapses and both particles realize their properties. But the godlike external observer is not the one making that kind of measurement rather, they are observing global properties, which leads to a view that nothing changes. The page orders thought experiment provides a possible solution to the quote unquote problem of time that arose out of that Wheeler to wit equation.
Right. Again, the Wheeler to wit equation successfully combines the theories of quantum mechanics and relativity into a unified theory of quantum gravity. But it assumes nothing happens in the universe. But now we have a way to explain how time might not exist as predicted by the page of Wooters dot experiment.
Right. Since to a Godlike observer, the universe is static but also allow for the perception of time to arise for internal observers like us based on witnessing how entangled particles change. So regardless of whether quantum entanglement truly explains time, what we can say is that the leading theory in physics to explain time appears to suggest that time is something that emerges. Now, there are other physical theories of time, some involving entropy entanglement gravity, et cetera.
But all theories come up short, none of them, no, you know, really seem to present a realistic description that aligns with our perception of time. And if the theory doesn't align with our perception of time, then it better have some, you know, solid, logical, logical and mathematical underpinnings right to support its case. But I would argue none of them do. In fact, I argue that the current physical theories for time all suffer from four core problems.
One, all the equations of physics are time symmetric which is a kind of nonstarter. At least in terms of current mathematics of physics being able to model what time is right. Time symmetry means things could move forward in time as easily as they move back in time. This is a well known issue at the heart of the problem of time. In other words, there is nothing in the entire mathematical apparatus of physics that cares which direction time moves.
The machinery of physics has no preference for direction. It's as though physics at its heart doesn't need to be concerned with time. Number two entropy while aligned with the second law of thermodynamics that tells us entropy always increases. Uh And and that seems or stays the same or increases in uh in closed systems seems to offer an explanation of the udi directional quality of time.
But it fails to account for the many instances where we see entropy decrease recall in my episode called Dodging Economic Reality, right? Where we saw how the economy itself is best explained via entropy reduction. Right? Since the economy and all of earth for that matter is an open system in open systems. Uh you know, a reduction in entropy is not only possible, it's actually highly likely a reduction in entropy is how life happens.
Since you know, a universe that only tends towards disorder would preclude large ordered molecules that are actually required for life. Right, open systems allow energy and matter and information to enter into the system which permits entropy to be lowered locally at the expense of increased entropy.
Everywhere else recall my episode called technology is humanity where I frame uh you know, technological innovation in terms of local entropy reduction, right, we see entropy decrease all the time we see change not only in terms of decay, breakdown and dispersal, but also coalescence aggregation and integration. The entire human effort to create things has our perception of time aligned to entropy reduction, not increase entropy.
In reality is far more symmetric than the second law of thermodynamics would suggest again, giving us no preference for direction. Number three relativity shows us that time is relative. So right off the bat, it doesn't do anything to pin down what time is right in relativity, there is no preferred frame of reference.
The man inside the box car is just as correct in saying the flashes of light hitting the back in front of the box car occurs simultaneously as is the man standing on the platform who thinks these events occur at different times? This means the past, present and future are on equal footing. Since if two people can disagree on when now is then they can also disagree on what constitutes the past and what constitutes the future when it comes to time relativity has no preference for direction.
And then we got the quantum entanglement stuff. Right now, quantum entanglement suggests time might uh emerge as I just discussed. But treating the evolution of a fundamental particle as a measure of time is not necessarily unidirectional. For example, the nonlocal correlations that arise from quantum entanglement may ex uh exhibit something called retro causality where an effect precedes its cause, right, such as a later event affects an earlier event.
For example, there's something called the delayed choice quantum eraser experiment that shows peculiar consequences of the well-known double slit experiment. Now, the double slit experiment is this well-known demonstration that shows light and matter displaying characteristics of both classically defined waves and particles, right. We've got the wave particle duality.
So so we can they think of you know energy coming through and it goes to the slits and sometimes you get the wave pattern, sometimes you get the particle pattern. It seems as though there's something fundamental within nature that where it can be both a wave and a particle, right. Well imagine a photon hits the detector. Let's say you're setting up the double slit experiment. Imagine a photon hits the detector such that it appears to have come from a single path. OK. So it's like $1.
Now, that would suggest that the photon must have entered the double slit device as a particle, right? Because you, you know, a particle would have one path. But if the pot uh sorry, but if the proton hits the detector such that it appears to have come from two paths that would suggest that it must have entered the double slit device as a wave that kind of got smeared out right now.
Imagine the experimental apparatus has changed while the photon is in mid flight, the photon may have to uh revise its prior commitment if you will as to whether to be a wave or a particle, even if we're talking about interstellar dimensions, a last minute decision made say on earth regarding how to observe the photon could actually change a situation that occurred billions of years earlier.
These delayed choice experiments have confirmed the seeming ability of measurements made on photons in the present to alter events occurring in the past. Now, it should be noted that this requires kind of a non-standard view of quantum mechanics. For example, if a photon is interpreted as being in a so-called superposition of states, remember I said that smeared out reality where nothing is determined until you measure it that would mean that it could manifest as a particle or a wave.
But during its time in flight, it's actually neither of those particle or waves, right? Because again, nothing is realized until you make the measurement. And in that case, there would be no retro causality since there was nothing to change in the past, if properties are not realized until the time of measurement. Now, this is the commonly accepted view, right? And the one consistent with the Copenhagen interpretation we've been using to discuss quantum entanglement.
But physics or at least philosophy is still wrestling with how to best interpret quantum mechanics. So the phenomenon of quantum entanglement does not currently give us a solid answer on the asymmetry needed to explain the perception of time. Right, I'm saying asymmetry because again, time seems to flow only in one direction quantum entanglement has no preference for direction. OK. So just a re uh you know, a quick recap, right.
Again, I think that that the current physical theories of time kind of suffer from format problems, right? One all the equations of physics are time symmetric. So the machinery of physics has no preference for direction entropy, we see it go up just as much as we go, you know, we see it go down just as much as we see it go up, right? We talk about building things.
So entropy in reality, you know, uh doesn't seem to have any real preference for direction either, I would argue relativity has no preferred frame of reference when it comes to time relativity doesn't seem to have much preference for direction. And then we talk about quantum entanglement even though this really depends on the interpretation you're using for quantum mechanics. And you can get into all kinds of paradoxes or seeming paradoxes like retro causality and all that.
So it doesn't have a final say. But actually, so that, so that that's those four points. And so to to wrap that up, I would say that you know, all the major efforts in physics to explain time currently fail for their inability to provide the asymmetry needed to describe the unidirectional perception of time. OK. The equations that underlying physics work equally well in both directions and should be increases and decreases during the course of human activity.
The reference frames at the heart of relativity are unbiased and quantum entanglement may still be plagued with peculiar outcomes like retro causality that suggest no preference to the direction of time. A paradox that can't Ruly be resolved until the proper interpretation of quantum mechanics is settled. Now, that's those four points.
But further the emergence described in the quantum entanglement experiments by you know, Marie van team that I discussed above it, they don't capture the change we notice at the macro scale, right, the kind of emergence we experience most in our everyday lives involves countless particles interacting in fantastically complex ways. Emergence is an aggregate level phenomenon and the level of aggregation needed to perceive time is arguably far more extensive.
Then what a two photon experiment could suggest if we extended the two photon experiment to say a trillion particles at the macro scale, are all those particles in our reality expected to be entangled. And if not, then how many and what exactly would it mean for someone to observe an entangled particle in everyday life? Considering we don't observe fundamental fundamental particles in our day to day existence, right? I mean, something just doesn't really add up there.
I believe what all this means is that physics is not equipped to solve the problem of time, at least not currently and perhaps never, it does not have in its toolbox, the necessary concepts, theories, methods or instruments to solve this challenge. While physics might hint that time could be emergent, which could very well be true. The physics approach to understanding time as emergent falls short.
I mean, the only physics theory supposedly hinting at emergence is rooted in quantum mechanics, which is the most reductionist theory of all. Again, the emergence we experience is highly aggregate and thus diametrically opposed to a theory founded on reductionism. I think physics being able unable rather to explain time is not just uh you know, kind of we're not there yet moment but rather a signpost of the fundamental limits of physics or at least its current paradigm.
Physics has never been able to properly address emergent phenomena phenomena, right, particularly of the strong emergence type as I discussed earlier, this is why chemistry is not applied physics and biology is not applied chemistry, psychology is not applied biology and sociology is not applied psychology, right? There are distinctly different things dealing with distinctly different phenomena that emerge.
So rather than trying to find time in kind of this bottom up fashion where elementary particles somehow lead to the emergence of time. I think we should instead start at emergence and where better to look than the human brain. The human brain is the most complex object in the universe as far as we know. And it has a mind that exhibits consciousness, the most emergent of all phenomena. The human brain is capable of two things that I believe are required for the perception of time.
One memory and two, the ability to ponder memory. Let's start with the first one. Memory is the ability of the mind by which information is encoded stored and retrieved as needed, right? The only reason we can perceive what we call time is because we retrieve memories of events that have already happened. We cannot retrieve events that have not happened obviously. So memory is how we are aware of what we call the passage of time. Let's take a more literal example.
There was a man named Henry Malaysian, born in Connecticut in nine in 1926. Now he had severe epilepsy. And underwent a brain operation to remove parts of the brain that were causing his fits. A consequence of this surgery was that he lost the ability to make new memories. He could only remember the last 30 seconds, which means he lived in a permanent present state. This shows how critical memory is to our sense of time. In fact, it may be what time is now.
My second point is the critical one I think, which is the pondering of time. We don't just retrieve information the way a computer retrieves data and information or the way an animal might avoid humans. If it, you know, had bad experiences with people in the past. This is a kind of reactive autonomous recall. It's it's a basic pattern recognition, but it's not pondering humans look upon their memories, right?
We think about when we were young, we recall Christmas parties, an old friend, good and bad experiences. We also use our memories to project into the future. I imagine scenarios that might happen. Our memories have the asymmetry that physics lacks. Well physics equations, entropy relativity and quantum and tango one don't definitively bias the direction of time memories. Most certainly do.
Our preoccupation with memories is arguably consciousness itself, meaning time could very well be the retrieval and contemplation of stored information by our consciousness. This provides the asymmetry needed to explain the arrow of time and rest on something we know about time that it's something we perceive using consciousness as the explanation of time would be thought of by many as kind of a crutch, right, for not being able to explain time at a lower level.
But this assumes that which is quote unquote fundamental exists at the lower levels of reality. Recall when I said that I take issue with, you know, the physicists use of the word fundamental physics assumes that which is fundamental much exists at the low must exist at the lower level at the bottom where you know small particles exist. But I think this is a remnant from the age of the enlightenment which you know, has kind of had its day.
I would argue right, uh which I've argued in other episodes before. But I challenge the physicists notion of fundamental. I think that it is far more scientifically correct to suggest that what is fundamental can exist at the aggregate level where true emergence happens. Emergence is not explainable using the parts that occur below it emergence is itself fundamental. Now, the idea that reality requires an explanation rooted in so-called fundamental particles and forces is deeply flawed.
I would say because it negates the very definition of emergence explanations are not more plausible when they are reductionist. In fact, if we are being intellectually honest, they are far less plausible for most of the phenomena we uh you know, measure and experience in everyday life. Any Bayesian attempt to update our priors is not strengthened by appealing to faulty premises if you want to get into kind of how we might update uh our knowledge based on a Bayesian approach.
But anyways, let's get back. So I'm gonna end this episode with some possibilities. OK. I don't have the answers to time, but let, let's open up some possibilities here based on my conversation so far, perhaps physics may not be needed to explain time because perhaps time only arises at the level that is immune to a physics based explanation. The realization that time arises from a retrieval and pondering of stored information is perhaps self evident.
Maybe the role of consciousness bringing time into our lives is the most fundamental thing we can say about time. But the self evident nature of time arising from our pondering of memories does not mean time itself is an illusion. There is a difference between what time is and the quote unquote arrow of time that makes time appear as though it ticks only in one direction. What time is is something that might be created via consciousness. And that is as real as anything.
But the perception of time as an arrow that moves in one direction could be somewhat illusory. There could be other options for how to perceive time. The fact that we perceive time moving in one direction means we need a theory that is asymmetric a theory that explains how the unidirectional perception of time might arise. Memory and consciousness provide this but the perception that time only moves in one direction might not be the only way to perceive time.
The fact that memory and consciousness explain our perceptions. And thus maybe at the heart of what time is, does not mean the perception itself is the only one possible physics being incapable of telling us what time is, does not mean. It cannot make important contributions to our understanding of how time might work. After all, the time dilation at the heart of relativity has real consequences, right? We make corrections to the signals used in GPS technology based on time dilation.
There are experiments that showcase the reality of simultaneity and all this kind of stuff. Perhaps the discoveries of physics that relate to time still provide a critical framing for our perception. Even if these theories don't explain time itself. For example, the consequences of special relativity suggests the past present and future may be on equal footing. Maybe it's the human perception that time must tick forward that makes us assume the past is gone. When in fact, it's as real as today.
Perhaps the future has already occurred. But it's our perception that the future comes after the present that makes us assume it has yet to happen. What does this mean to our everyday lives? Well, I think a change of perception is a kind of change to our reality. I mean, after all, we usually hear a perception is reality, but kind of think of that more literally, right? Losing a loved one seems to mean that they are gone forever.
But this is all based on the perception that the past is over and never to return. The idea that we want a career in five years can seem like an insurmountable goal. But this assumes the future is far away and that anything can happen between now and then, I mean, we know from Einstein's relativity, that time is intrinsically linked to space itself.
So if the passage of time is either somewhat or completely illusory, then perhaps space is as well, the vast distances that separate people can make us seem detached. But maybe those distances don't really exist fundamentally. Perhaps the vastness of the cosmos is more perception than reality. Changing our perceptions, changes our realities. And when it comes to time and space, such changes can add meaning to our lives. Memory and consciousness may provide the arena in which time plays out.
It may be. What time is memory and consciousness may, may kind of provide the fabric of time if you will. But how we use that fabric to navigate our lives can be altered. Maybe the way we reconcile the limitations of physics with the emergent reality of time is by using what we discover in science to augment our perceptions that play out against the fabric of our consciousness.
In any case, we have reached the point in our discussion where current science appears maxed out and even the philosophical considerations become strained under the stress of paradox and hard to reconcile realities. So perhaps I'll leave it there for now, whatever that means. Ok, that's gonna be it for this episode. Thanks so much for listening. I'm Sean mcclure and you're listening to Nontrivial.