Talking about time with Lauren Cabrera

(Please note: This transcript is AI generated and has not been edited for mistakes... but it is better than nothing!)

[00:00:00] I'm just going to get right into it with this. I brought in. Lauren Cabrera, who was my daughter's. Sixth grade science teacher to help me. Describe time through the lens of physics. And, uh, and so what you're going to hear is our conversation. Where I just wanted to make sure that I didn't totally, totally mess it up.

So enjoy Unpacking the arrow of time. And Y, i think science is astonishing. 

 I'm doing a really deep dive this season in my podcasts, into all things time. And I wanted to start 

Bree Luck: with what is time , so like for the past two months I've been reading and reading and reading and I've loved it, right? I've been totally nerding out, but I'm not a, I'm not a scientist, I'm not a teacher. And I don't [00:01:00] even know if I have this right. Like, I don't know if I have it right.

Yeah. 

Lauren: Well, and I, I mean, I don't know if I'll have it right, , but 

Bree Luck: So anyway, the idea is that I'm gonna go through my little podcast lecture.

Yeah. And I'm gonna stop at points and be like, Does that sound right? And then we're gonna talk through it. Perfect. I've been reading Sean Carol's books .

 I've been reading Carlo Ravelli. 

Bree Luck: He's an Italian, like . He's super sexy. , like I love nerds. Um, he is an Italian, uh, uh, physicist maybe, or philosopher.

You know, they're kinda all, they all lump in together. , I know. for today. I just wanted to like, Have a great teacher on Aww. To tell me where it makes sense and doesn't. 

Okay. now I'm gonna actually introduce you. 

So today I have. My friend Dr. [00:02:00] Lauren Cabrera on Lauren, You just got your PhD? Yeah, I did. I did yesterday. Yesterday, yes. And your PhD is in education?

Lauren: It's in educational 

psychology. So it's what motivates students?

How do they learn? How do they regulate themselves 

Bree Luck: during learning? Oh my gosh. I could talk to you forever about this stuff. , Dr. Cabrera was also my daughter, Camden's. Seventh grade, right? It was seventh grade, sixth grade, I think sixth grade. Her sixth grade science teacher.

And let me tell you, you lit a fire in my kids' brain. I mean, she's always been a curious, engaged student, but you opened up a whole world to her and made her feel safe to love science. 

Lauren: Yes. The benefit of having her in sixth grade was I also then got to work with her for the next two years in after school clubs

so it's just been a gift to get to know her, [00:03:00] like see her grow into a young woman and get to know you more. 

Bree Luck: Aww. So the episode that dropped today? Yeah. About. Is sort of my introduction to the episode that we are recording right now. Mm-hmm.

and it was basically about how afraid I am to explore time from the perspective of physics because I'm not a physicist. , Yes. 

Lauren: Yeah. I, I'm not either 

Bree Luck: and I would say I'm not a scientist in any way. And so I thought, who is a scientist that I could bring on to look at this from a real.

Real bird's eye perspective, right? Like, we're not gonna try to go deeper than either of us feels comfortable going with this, but I just wanted somebody to hold my hand. Mm-hmm. . And, and also, um, tell me if I get a b plus on this assignment. , that's where I'm gone forward is being we work for passing, We'll work for passing

Okay. So physicists, [00:04:00] That is the right word, right? Yeah. Yes. I mean, it's a really funny word, like, it's like sysigy. . Yes. So physicists. Probably understand more about time than any of the rest of us do.

Mm-hmm. , right? I mean, because they have made such a study of, of time and space and matter. Yes. And as I understand at the fundamental laws, we're not getting into quantum physics, the fundamental laws of physics, don't show any kind of directionality in time. 

Lauren: No, no.

Bree Luck: So we, you and I see time as like passing or flowing. Because our experience of time as normal human beings who are not physicists, is that we feel a directionality right from past to present. To future. Yes, yes. But to a physicist, time looks a little bit different. 

Lauren: Yes. Yes. Cuz humans will put things in [00:05:00] perspective of themselves and so they'll think of their lived experiences and put time in terms of that.

Whereas, especially theoretical physicists will think of the whole system outside of the human 

perspective. 

Bree Luck: We can never really get outside of the human perspective. We're stuck in our brains, unfortunately. But even to try to do that, I just think, I think it's the most admirable thing.

I think it's so cool.

Lauren: It is. It is.

Bree Luck: So I'm gonna zoom out a little bit and we're gonna talk about planets , ok? Because we know that. Planets in the solar system, travel around the sun. Mm-hmm. . And we can choose any moment of time if we're looking at it from a, from the perspective of physics. Mm-hmm. , we can choose any moment of time.

And with the right tools, we can pretty much figure out in general, where those planets are.

That's [00:06:00] their position. Right. And how fast that you're traveling. And that's velocity. Mm-hmm. ? Mm-hmm. . Yeah. Dr. Burke from my physics class. . There you go. . And we can look at it in any given moment of time. And so with this information, physicists use equations that's MATH.

Lauren: Yes. 

Bree Luck: To pretty much figure out where those planets will be like next month and also where they could have been 5,000 years ago. Yes. And you can use the fundamental laws of physics and those fundamental laws of physics. Cover gravity. Mm-hmm. . Electromagnetism. Mm-hmm. . Weak nuclear force and strong nuclear force.

Like that's like, I don't even get that . 

Lauren: Yeah, yeah. Agreed. 

Bree Luck: But they use all those things to estimate backwards or forwards in time and they have some pretty good accuracy Yes. With that, 

right? 

Lauren: Yes. And have for thousands of years, 

which is remarkable. So cool. [00:07:00]

Yeah. Ancient astronomers and the accuracy that they had and all of those predictions that you were just talking about is fascinating.

Yes. 

Bree Luck: So for thousands of years. Mm-hmm. , they've been able to describe any point in time, whether it's a million years in the past or a hundred years in the future, or the day that you get your PhD from Virginia Commonwealth University . 

But this is like at the planetary level, right? This isn't. What's gonna happen to Lauren Cabrera in 1998? No. No. Were you alive in 1998? I was . Okay. . I was nine. . So the point is that there is no greater value and I think value is really important, right? Mm-hmm. . Cause there's no greater value placed on the past or the future in terms of data.

Lauren: No. 

Bree Luck: At the cosmic level, there's just this basic symmetry of knowledge. Mm-hmm. of the past in the future. Yep. And we also had this kind of [00:08:00] symmetry, so that's way out in space. Right. But we also had that, the microscopic level. Yes. Subatomic level. Right. Yeah. That's so freaking cool. I know. So the concept is that the properties of tiny little particles of atoms and molecules remain unchanged after being subjected to a variety of symmetry transformations.

Right. Or those are operations. Yep. So like at the big level and the tiny level, it looks the same. Yes. 

Lauren: Yes. Even down to the, like the mathematical equations used to like predict their movement and stuff. They're very similar. 

Which is fascinating. 

Bree Luck: So cool. Yeah. Okay, so here's a question then, because I I can't even, like, it's like telling me that I have $10 million in my bank account.

 I cannot fathom that much money. And that's sort of how I feel about this, right? 

Lauren: Yes, Yes. Understand completely. 

Bree Luck: So 

Lauren: like, 

Bree Luck: one of the examples That I think I heard that. [00:09:00] I wanna just make sure that I get it. Is like, basically if I look at it at sort of a, a human scale level mm-hmm.

if I throw a ball in the air, I can trace its course in the air mm-hmm. . But then if I did it backwards, 

If I went backwards in time, it would trace the same course. 

Bree Luck: . Yes. Yes. And that's, um, time symmetry basically. Mm-hmm. . Okay. Cool. So here's where it gets a little funky , because in real life it doesn't feel like that.

Lauren: It does not, 

Bree Luck: and we don't experience it a lot of times at the physical level, like an egg. If I have an egg in my hand and I throw the egg in the air and chart, its. I can't, it's gonna be broken , like Right. I can't put the egg back together. Yes, Yes. 

And that is how we [00:10:00] experience time, right. There's an egg, there's a broken egg with a yolk on the ground. Mm-hmm. can't put it back. That's the difference between past and present. 

Lauren: Yeah. Cause and effect. 

Bree Luck: Cause and effect. So this, is called asymmetry of time.

Mm-hmm. this experience of time. Mm-hmm. . Right. And it's a one way direction. From past to present to future. Mm-hmm. . And then there's this, I read that there's the dude who came up with this term of the arrow of time, like, Oh, I've never heard that. Arrow of time. Sir Arthur Eddington. Okay. In 1927. Wow. I mean, I know, I know.

Lauren: It's surprising it took that long to come up with the term. 

Bree Luck: I think it's really probably, It was attributed to him, doesn't, Yeah. Yes. Yes.

Lauren: Cause I imagine that this. Construct, like this idea of it has been around for 

a long time. Yeah. 

Bree Luck: And he's a sir, right? So he's, he's probably some privileged white [00:11:00] dude who had access to something getting published and so he got it.

He got his name affiliated with Arrow of Time. 

Lauren: There you go. .

Bree Luck: That's the way it works. Mm-hmm. , most of the people who do this are privileged white dudes, so it's really. Yeah, who 

Lauren: happened to be working with the people that were actually doing it? 

But anyway, . 

Bree Luck: Oh, thank you. Thank you. Can you just say that again, , 

Lauren: who happened to be working with the people that were actually 

doing the work?

Bree Luck: I just wanna take a moment to send appreciation to all the people who are unrecognized for the incredible work that they have done. Yes. Yes. Oh, thank you for bringing that up. Of course. Okay, so the arrow of time is what gives us an impression of time passing. Yes. Right now, we, we, you know, dreamers and teachers and dishwashers and parents are acutely aware of time passing.

Mm-hmm. . [00:12:00] And what's more, because of our experience of time, we have this bias. And the bias is super interesting. Yes. The bias is that we can use our memory and you know, in scientific terms, artifacts, , mm-hmm. . Mm-hmm. , right. 

Or our records, which we know are not always. True. 

 As you just pointed out. 

Bree Luck: Yes. But we use those to have a pretty good idea.

Some of the things that happened in the past on sort of the, we'll say the human scale. Yes, Yes. Right. And then we have our current experience that we think is accurate. But as someone who has studied psychology, we know that. That it's relative, right? There's a lot 

relative. Yeah.

Lauren: It's all, It's all up to your interpretation and your perceptions of the world and your worldview and Yes. The way that we see the world around us drastically changes based off of the person interpreting [00:13:00] it. 

Bree Luck: Right. the future though is like a complete crap shoot. . Yeah, My guess. We actually really don't, we really don't know.

No.

So like I predicted this morning that I would pick up my daughter from school this afternoon. That's why I set our appointment for now. And I predict that I'll make it down to Georgia to visit my family for Thanksgiving. Yes. And I feel pretty certain that I'm gonna get a bill from the IRS at some point.

Right. Like those are things that I can predict. Yes. But today, my husband decided to pick up my kid. So that prediction didn't come true. So you didn't have to Yeah. No. And then of course, my flight to Georgia could be canceled. Yeah. Could not make it down there.

Mm-hmm. . And um, and I don't know, maybe the IRS will decide to. Stop taxing people who are butchering the laws of physics podcast. But in general, we have this bias that what happened in the past is done. What happens in [00:14:00] the present is real, and what happens in the future is subject to change, but that we also have some agency over what will impact the future.

We do, 

yes. Yes. Like you have more agency over, you know, your, your tomorrow's schedule potentially over the hurricane that could then disrupt flights, 

right.

******

So I wanna talk a little bit about that bias. Yeah. . And this is where it gets pretty controversial. we're gonna get into entropy a little bit. Sure. So right now in the popular world of physics, the widely held belief seems to be that most of the reason that we see time as having a forward direction ultimately comes down to thermodynamics. . Yeah. And so thermodynamics is the science of heat and its relation with mechanical energy, right? [00:15:00] Mm-hmm. . Mm-hmm. . Yep. 

Did you know that there's a zero at law at thermodynamics? 

Bree Luck: What the heck is a zero at? That feels like a mistake. 

Lauren: They made up the 

first three and then found one that was preceding it and didn't have a number before one except 

zero. 

Bree Luck: It's like the Star Wars movies. It's like going back. Yes. Anyway, we're not gonna go through all the laws of thermodynamics 

 But the second law of thermodynamics is the one that we're going to talk about today because it hinges on the concept of entropy. 

Bree Luck: So I think of entropy as like my 12 year old car needing to go to the mechanic more often, right? Yes. But in physics, we get a little different view. Mm-hmm. and the second law of thermodynamic says that as one goes forward in time, mm-hmm. , the net entropy, which is defined as the degree of disorder.

Mm-hmm. of any isolated or closed system will always increase. Yes.[00:16:00]

Always feels like a really strong word. Like it hurts me to hear that word always is I, 

I agree and especially like in science terms, but do the way, the reason they can use that term is because they bound, the 

system is closed. Okay. Okay, so closed systems are when 

you just focus on the one thing, like you're, you're one car needing 

to go to 

more, but then if you think about it as an open system, then that changes the whole 

thing completely.

So if we have a closed system, is the universe a closed system? Like is that when we're looking at it this way, is the universe 

Lauren: typically 

people will like bound a closed system to help then describe or, make sense of things that are hard to make sense of. If you make the closed system too big though that no longer has that purpose.

Okay. That like, to me that's more of an open system. When you see things more interacting, 

 So I 

guess on a [00:17:00] planetary level, yes, it could definitely be like said as a closed system because you're dealing with like then everything else around 

Bree Luck: it. But on experiential level, yes. We look at smaller, like for us to be able to wrap our brains around it, those of us who can't imagine $10 million in our bank account, it helps to think of a smaller closed system when we're doing right.

Great. Totally understand that. So Thank you for describing a closed system there. I'm gonna get the technical definition. Two, It's a physical system that doesn't exchange any matter with its surroundings and isn't subject to any net force whose source is external to the system.

 I like to have both, so thank you for that practical explanation of it. Okay. Okay. So we have that. Mm-hmm. . Now this part is actually really important. In terms of time. Mm-hmm. . Cause there's this guy Ludwig Bantzmann he's Austrian. Mm-hmm. . And he came up with a statistical explanation for the second law of [00:18:00] thermodynamics.

Mm-hmm. . And his statistical explanation is basically a way of counting how many ways there are to rearrange the constituents of a system so that it macroscopically looks the same so essentially as time progresses, I am talking about this actually in terms of a solar system level here.

Lauren: Okay. Okay. 

Bree Luck: As time progresses, we are moving to more and more possibilities of recombining all the different parts of our realm. Yeah. Right. I don't know. I just like, I like, I find this whole thing of entropy being recombining, just so comforting. . 

Lauren: Yeah. Yeah. Well, cuz it, it helps like, so if you think about your egg example Yeah.

 There are so many things that could then happen with it. Like the possibility of it going back to that original egg form just spontaneously is so close to zero because, Entropy is just like 

increased so much. Yes. I also think of [00:19:00] aging . Yes. 

Bree Luck: I'm not gonna go back to being 19 year old, Bree not gonna happen. Mm-hmm. But if I'm thinking of it as like I'm, I'm just rearranging , like everything is just rearranging. Yeah. Then it, I don't know, It just feels like there are more possibilities for me as I move forward.

Right. Just like on an emotional level. It's kind of nice. It is. It is.

Lauren: When you're thinking about time, like really honing in on that agency that you were talking about, 

that that helps. That helps make you 

feel more in control. 

Bree Luck: Yeah. Yeah. Or even if not in control to find, greater curiosity.

Yeah. Within that . greater curiosity for me leads to greater peace. That's just how I function. This is my weird old brain. Mm-hmm. . Anyway, back to the universe. Yes. So, how does this relate to time? Mm-hmm. , Well, what these physicists [00:20:00] say is that, and this is batsman and also particularly Sean Carroll that I talked about in the last podcast. Basically 14 billion years ago there was the Big Bang. Mm-hmm. , and for whatever reason, Whatever reason, that was a low entropic event that there was very low entropy in that. Mm-hmm. and I, this like, I, this really got me caught up for about three days because I was like, Why

Why was, Yeah. Cause we think of it as so 

Lauren: powerful and such a big start, but then to have it categorized as low 

Bree Luck: entropy. I know. Yeah. It, it sort of goes against our natural logic ? Yes, yes. Or at least our semantics around that. Yes. Yeah. 

Lauren: Logical flow then says if as you like, increasing time increases entropy, so if you decrease time, it should decrease entropy.

That can make sense.[00:21:00]

Bree Luck: There you go. I think you just got it. And I might have to listen to it again to get it . It's okay. so anyway, ever since the Big Bang, which we will just assume, we'll assume that the physicists know what they're talking about. It was a low entropic event. Mm-hmm. . And since then, we've been progressing to a period of high entropy.

Mm-hmm. and right now, We are in what's called a period of complexity. Okay. do we, we don't really need science to figure that out though. . We have, 

Lauren: We'll get your phone for a hot second. Know 

Bree Luck: that. 

 So that is basically, The explanation of the arrow of time. Mm-hmm. through physics. I'm gonna just, I wanna try to explain this in one other way, and this is why I want, I really want you here too,

 So on earth. We're going back to like our system of Earth. Mm-hmm. , we get our energy mostly from the sun in the form of visible light, uh, on which [00:22:00] all life as we know, it depends.

Mm-hmm. , do we agree on that? Yeah. Okay. The cool thing is that we, on Earth, all of us radiate that same amount of energy back out. Yeah. But we do it at. One 20th of a photon of energy from the sun. So we are radiating the same amount out that we get in, but it comes in like one photon gets divided up into 20 whatevers.

Yeah. To radiate back out in the form of, uh, infrared. Is that right? Infrared race? Probably. Yeah. Yes. Yeah. We radiate it back. Yeah. Yeah. 

Lauren: Cause the sun is really giving off the whole electromagnetic magnetic spectrum. We see the visible light, but we do, there is, there's like more waves that we can't see coming from the 

Bree Luck: sun too.

Great. Great. So the sun's raised, so let's correct that. It's [00:23:00] not just visible light, it's it's sunlight, it's light from the sun. All. All light from the sun. It's electro magnetic waves. Is that great? Thank you. Thank you so. This is entropy in action, right? Like we're seeing it right there. Cause the sun sends one photon of light our way, and then on earth we have plants that photosynthesize.

Right. That's breaking it up. We have animals that take in the oxygen, eat the plants. Right. We have humans who eat the plants and the animals. Yeah. And then we dance and cry and make babies and it's sunburn. That's sunburns 

Lauren: in acting to the electromagnetic waves, Clouds the atmosphere will 

Bree Luck: absorb it. Yeah.

Lauren: You get like the northern lights 

Bree Luck: because of that. You can see them. Oh, so cool. Those are the coolest thing. Yeah. But basically, in doing all that we do, and sitting here and talking to you mm-hmm. , we are taking the sun's energy and then radiating it back out. [00:24:00] We're reorganizing it. Restructuring it, and then radi it back out into the solar system.

Yes. Yes. So entropy is not, not just why you need to put a roof on your head every 20 years. It's the stuff of light and art and freaking snowflakes. Yeah. I just think that's the coolest thing. It's . 

Lauren: That's why I got into science to begin with, is like just figuring out like why things happen the way they do and patterns in the natural world and things like, Yeah.

Bree Luck: I find it fascinating. Well, I think that's it. I mean, I think that that's like the basic explanation. Time. Yeah. From perspective of physics. From , my very limited vantage point, but But it is more, 

Lauren: it is more than most people will ever think about time 

Bree Luck: and better. Well, not anymore. No, No. Everybody's gonna think about time

Yeah. So thank you for [00:25:00] taking your time to be with me. You're so welcome. 

Lauren: You're so welcome. I can't wait to see, I can't wait to hear all about the 

Bree Luck: series. 

It's a fun one.

So that was the brief explanation of time through the lens of physics. Big, thanks to Lauren Cabrera for coming in to help me out with that. And I just want to give Note of appreciation to all the great teachers out there. Putting this episode together really gave me a greater appreciation of all that you do every day. . And next time we will talk about why there are 12 hours in a day. It'll be good. Talk to you soon stay curious y'all