Discerning Truth: Dialog on the Age of the Earth - Part 6. Distant Starlight

Thanks, Jason Lowe here with Discerning Truth, the podcast of the Biblical Science Institute. We have in the last several sessions been looking at a dialogue I did with Dr. Hugh Ross some time ago, and we've been analyzing some of the things that he said, some of the things that I said, maybe some of the things I could have said better, but hindsight is 20 -20 as they say.

We're going to continue that analysis today, and we're going to look at, in particular, the distant starlight issue. So I think a lot of you will find this very interesting, and we'll even go into a little bit of the physics of Einstein, nothing too in-depth, but I'll show you some resources you can get to learn more about this issue, because I think here is one of the real strengths of the Biblical timescale.

When you understand the physics of Einstein, the physics of what's called relativity, you'll find that it's easy to get starlight here, even instantaneously, even today, it's not a problem for the Biblical timescale, and I think a lot of Old Earth creationists don't realize that.

So let's have a look, and I hope this will be helpful to you.

Let me ask you this. When we look at the sun, do we see the sun as it is right now, or do we see it as it was eight minutes ago?

Well, it depends on which Sanctity Convention you use. If you're using the Anisotropic Sanctity Convention, we're seeing it as it is right now. If you're using the Einstein Sanctity Convention, it's eight minutes ago.

And Einstein would say those are both equally legitimate conventions. Even the way that Dr. Ross asked that question suggests that he doesn't really know much about the physics of Einstein, because if you understand the physics of Einstein, you know that any question, how long does it take to get from here to here, will depend on the reference frame, and frankly, the Synchrony Convention.

This is something, again, that Einstein discusses in his primer book on relativity. It's not hard stuff, but it's something that he talks about, again, in page 23, the idea that the speed of light in that direction is the same in that direction.

How do you know that?

Einstein says you can't know that. That's just something we're going to stipulate, and it gives you a definition of simultaneity. He makes that very clear on page 23, right? Talking about the speed of light being the same that way as that way is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which I can make of my own free will in order to arrive at a definition of simultaneity.

So that's one way of defining now. This is the whole question. What does now mean over there, you see? In order to say how long does it take for something to get from there to here, you'd need to have a clock there, at least in principle, to tell you when the object left, and you need to have a clock here to tell you when it arrived, and those two clocks would have to be synchronized.

But the problem is there is no universal objective way to synchronize two clocks that everyone in the universe would agree upon.

Can't be done.

That's one of the things that Einstein discovered. That's what makes his discovery so profound. And then the other thing that Hugh Ross is missing is the relativity of simultaneity, which is, again, this is an early chapter in the book.

You can see here relativity of simultaneity, and that has to do with the fact that even if you make the assumption that the speed of light is the same that way as that way, which is called the Einstein Synchrony Convention, nonetheless, the amount of time it takes for an object or even light to get from here to here will depend on the reference frame of the observer.

In other words, if light takes eight minutes to get from the Sun to the Earth, according to my reference frame, then someone else in space who is moving relative to me would not say eight minutes. They would give a different answer.

It might be four minutes. From the light's point of view, it's zero, because that's the proper time between the two is zero.

Yeah.

But again, these measurements of supernovae are actually established.

And I refuted that on the website. You need to take a look at it, Hugh. Hugh, I love you, but you don't know what you're talking about. You cannot distinguish a convention by measurements, and that should be obvious, because you need a convention in order to perform measurements.

And so when it comes to, for example, the one-way speed of light, that is a convention. It's something we choose, and that tells us how to synchronize clocks. Then once we have our synchronized clocks, we can begin measuring one-way speeds.

But the problem is, you can't measure any one-way speed unless you already had synchronized clocks and therefore had already chosen the one-way speed of light. So no, you cannot, by supernova or by any process, measure objectively the one-way speed of light without first assuming the one-way speed of light.

That is the conventionality thesis. Einstein wrote about it. Hugh, you need to read up on this topic.

And I will agree with your reputation, and so do the astronomers who wrote the paper on that supernova. Again, they saw three separate supernova eruptions from the same event over a three-year period of time.

Hugh's made a lot of mistakes here. First of all, he's talking about a gravitationally lensed supernova. He mistakenly said it produced three images. It actually produced four images, and then a fifth one was produced a year later.

And then he said it happened over three years. No, it happened, the four events happened simultaneously, and then the fifth one was one year later, not three years later. And that kind of thing is very rare.

There are only two cases of a gravitationally lensed supernova that we have in terms of our records. And one happened in 2014. That was the Raphstahl supernova. And then another one happened in 2016. Okay, so what is a gravitationally lensed supernova?

Well, basically, a supernova is when a star explodes. A couple of different kinds. We won't go into details. But it becomes very bright when that happens. It releases an enormous amount of energy, and the star briefly becomes brighter than the entire galaxy that it's in, all the other hundred billion stars in that galaxy.

Now, a gravitational lens has to do with the fact that gravity, mass has gravity, and gravity pulls on light. The effect is generally very slight. That's why we don't notice it on Earth. Our gravitational field is very faint, so light doesn't seem to be falling.

But it is falling. It's just light moves so fast we don't notice it. But what happens is you have this supernova, this exploding star at incredible distance.

Away.

And then in between that exploding star and the Earth is a galaxy or a cluster of galaxies, in the case of the Raphstahl supernova. And what happens is the light is initially not aimed right at the Earth.

Initially, it's aimed up a little bit. And then it gets bent by the gravity of all those stars in that galaxy until now it's directed toward the Earth. And so it comes straight toward us at that point.

And you can actually get multiple images because maybe some of the light goes above the galaxy, some of it goes below and gets bent up, some of it goes to the left, some of it goes to the right, and eventually comes and hits us.

And this happened in 2014. We saw four separate images of the same supernova because they had taken four different paths around this cluster of galaxies. And then based on the estimated mass in that cluster, astronomers predicted that we might see a fifth image in 2015, which we did.

It was right where it was predicted to be. In November or December of 2015, we saw a fifth image where light had taken a longer route and then had gone to the Earth that way. And so we saw a slightly more displaced image of that same supernova.

Now, the only other time that's happened, it happened again in 2016 with a different supernova. And this one happened with a single galaxy, and it produced four images, and that's it. There's no fifth because it's a single galaxy.

And so the timescale is very tight. Now, the interesting thing is because in the first case, in the Revstel supernova, the fifth image took a longer time because it took a longer path. And I think what Hugh is assuming is he's thinking, well, that proves that the speed of light must be the same in all directions because if it was instantaneous toward Earth, then perhaps all five images would have arrived at the same time.

And if that's what he's thinking, he's mistaken because I've answered that claim on the Biblical Science Institute website. There's a Refuting the Critics article where I did where Peter had made that very claim.

And what I showed was he's not thinking consistently because the light from that supernova, it's not initially directed toward the Earth. You see, in the Anisotropic Synchrony Convention, which is, I believe, the convention the Bible uses to describe celestial events, light, when it's directed directly toward an observer, is instantaneous.

It takes no time at all to get from there to here. But the return trip, if you wanted to send a signal back, it would travel at half C, half the round-trip speed of light. And that makes the round-trip speed of light C, which is 186 ,000 miles per second.

Quite fast.

But what about intermediate angles?

What if the light's not directly toward you, but kind of toward you? Well, then it's not quite instantaneous. It'd be faster than C, but it would not be instantaneous. And when I answered Peter's objections, and also this is in my original article on this topic that I published back in 2010 in the Answers Research Journal, I gave the equation for intermediate angles.

And so what happens with the supernova, the reason you get the four events, the first four images at about the same time, is because their angle away from the galaxy is the same. And so they travel at finite speed until they're bent around, and then they speed up, and then they zip to Earth essentially instantaneously once their direction is directly toward the.

Earth.

The fifth image, the light traveled at a deeper angle, a larger angle of departure, and therefore the speed would have to be slower, according to the Anisotropic Synchrony Convention, until it gets bent around.

So it reaches the mass of the cluster later than the other four images, which is why it arrives a year later. And so it's perfectly consistent with the Anisotropic Synchrony Convention. It's just, I think Hugh hasn't bothered really to study this.

Hugh mentioned something about the astronomers who actually made this discovery. Yeah, I've read their papers, and there's nothing in those papers about the one-way speed of light, or using supernova as a measurement for one-way speed of light.

Round-trip speed of light? Sure, that you can measure. One-way speed, you can't measure. There are other cosmological factors that you can derive from supernova observations, but the one-way speed of light is not one of them.

We'll take a look at some of those papers here in just a few minutes. Let me bring up my website, because I don't know what else to do here, because what you're saying has been refuted. This is why scientists debate issues not in informal dialogues like this, but in the technical, peer-reviewed literature.

You see, in a debate like this, you can just make claims, and it's very hard to know who's telling the truth. But when it comes to a peer-reviewed document, you can take a look. You have to back up what you're claiming, and you have to provide references, and if you make a claim that's false, somebody can take a look at the reference, and they can see that it's false.

I have already refuted the claim that Hugh Ross made, and it is on the website, and this is under the title, Refuting the Critics, Distance, Starlight, and Ask, A-S-C. So I'll put the link up there for you so you can see that.

I'm not going to take the time to read it now, but you can see in this article, I deal with this idea of a supernova and the gravitational lensing of the light from those supernova, and the fact that you cannot use that to establish the one-way speed of light.

You can measure the round-trip speed of light, but not the one-way speed of light using this kind of scenario.

I've shared this with you on the first debate we made.

It was just as wrong then as it is now. You can't determine one-way speeds from a supernova, or really from any measurable phenomenon.

Namely that, look, okay, if you want to have this kind of a technical debate, we need to do it in front of a trained audience.

No.

The way scientists settle these kinds of debates is in the peer-reviewed technical literature. That's the way we discuss these things, and there's a reason for that. You see in an informal dialogue like this, or even in a formal debate where you have experts in the field there, you can still make these quick claims that the other person can't check because of the constraints on time.

But in the written literature, you can't get away with stuff like that. Think about, I mean, just think about in the past few podcasts that we've been covering, think about all the things that Hugh Ross has said that are just demonstrably false, and I've shown you that, and I've been able to do that because I can come back and I can take a look at it, I can look at the literature.

For example, Hugh makes this claim that there's no lexicon, there's no Hebrew lexicon in the world that would claim that the use of yom as a long period of time is figurative or non-literal. Well, I gave a counterexample.

Strong's Concordance does that. But you see, unless you're aware of that in the middle of a debate, you can't answer that. That's why peer review occurs in written form. Now, if Hugh wants to debate me in a written format, I would be delighted to debate him on this issue.

In fact, Hugh, if you're watching this, I invite you to write up your criticism of the conventionality thesis. I'll publish it on my website along with my response, because I don't think that you can defend that issue.

And so I'm willing to do with you what I did with Jason or with Danny Faulkner. Let's have a public debate in front of a panel of evangelical research astronomers and get their judgment on the debate.

What you've said is very revealing, because you see, it reveals our different standards. Your standard for what determines truth is minds of men. My standard's the word of God. That is the fundamental difference between our two perspectives.

I've noticed that when Hugh gets back into a corner, when he has posed to him a question that he simply can't answer, or he's trying to defend a claim that he really can't defend, and he'll say, well, these other people agree with me, or let's have a debate, and we'll have these other people who are experts on the issue.

And by the way, I'm fine with having other experts on the issue weigh in on this, but I think anyone who's knowledgeable of the physics of Einstein would not agree with Hugh Ross on this issue anyway, because Einstein certainly didn't.

Einstein agreed that the one-way speed of light was conventional and that there is no experiment you can do to measure it, even in principle, because the one-way speed of light defines how we determine what is simultaneous, when two events are separated over space.

But the way that scientists debate these issues, again, it's not in front of a panel of experts where it's a verbal debate. No, it's in the written literature. That way, any claim that Hugh makes that is dubious, I can check it.

And that's fair to him, too, because any claim that I make, he can check it. He can go and check the literature, and so on. And so if you really want to get to the truth of the issue and not just engage in posturing, the way you do it is in the written, peer-reviewed literature.

And I'm very happy to engage Hugh in the peer-reviewed literature.

No, it isn't, because I believe in the authority of Scripture just as much as you do. It's a difference of interpretation.

I don't need a wall of experts to decide these things. I stand behind what I said, but I wish I'd answered that a little bit differently. Because I do respect experts, and I think it's fine to bring in experts and say, you know, here's this claim that we're making about physics.

You're a physics expert. What do you have to say about that? That's fine. But a greater level of authority than that, a greater level of expertise, would be to consult the peer-reviewed written literature.

Because in that case, you've had several Ph .D. physicists, Ph .D. astronomers, astrophysicists that have looked it over that have said, this passes the muster. This is good stuff. And since it's published, it's out there.

Anyone can look at it. It's open. It's objective. And if it has any errors in it, people will jump on it. But you see, when you just say something in a verbal dialogue like we're doing here, you can make all kinds of false claims.

And it's very hard to very quickly demonstrate that that's wrong, because I can't pull up the paper right next to me that refutes that. So the written literature is superior to a panel of experts, because in written literature, you have a panel of experts who have had plenty of time to think about the issues and have had time to go back and check all the references as well.

That's a superior level. And beyond that, the Bible is my ultimate authority. It's superior even to the written literature, because it is written literature that's inspired by God and therefore inerrant.

And for all his claims that, well, you know, he believes in biblical authority too. Here's the problem. When you make man the interpreter, the ultimate guide to interpreting the scriptures, and I believe that's what Hugh's doing.

He might say he's not, but I believe that's what he's doing. Then man is really your ultimate authority and not the scriptures. Yes, Hugh and I do have a difference of interpretation. But the Bible tells us how not to be interpreted.

The Bible's self-interpreting. And I would argue that Hugh is not following the Bible's interpretation of itself, because the Bible tells us how to interpret days. It tells us how to interpret Genesis.

Take a look at the way Jesus did. Take a look at the way the New Testament authors did. Under the inspiration of the Holy Spirit, they interpreted Genesis as literal history. Jesus said from the beginning of creation, God made them male and female.

He obviously didn't believe that there were millions of years between the creation of the universe and the creation of human beings. And again, this issue of, but we're talking about the science of the age of the universe.

I know.

But ultimately, the age of the universe is something that the Bible addresses. And when something is addressed by scripture, we need to take that as paramount. The science is secondary. Now, I think the scientific evidence strongly confirms biblical creation.

All kinds of examples. We've mentioned some already. We didn't get to a lot of others that I could have mentioned. But ultimately, since the Bible does address the time scale of creation, namely it tells us God created in six days.

There's a verse I can point to, Exodus 20, 11, in six days, the Lord made the heaven, the earth, the sea, and all that's in them. That settles the matter. The science is secondary, though I think it does confirm biblical creation.

But, and this is just coming from me, I'm not taking sides or anything, but if we do appeal to scholars who agree with you, isn't that going to be based upon the presuppositions that they bring to this issue?

So that if they agree with the presuppositions that you have, which are related to how you interpret Genesis, that's going to affect how they interpret the data. So wouldn't the real debate be over the presuppositions with which we bring to the data, which then lead to the particular conclusions that we come to?

Exactly right. This really is an issue of differing presuppositions. I don't believe that Huros is epistemologically self-conscious. I don't believe that he's aware of his own presuppositions, except perhaps minimally.

He holds to uniformitarianism. He'll admit to that. And to some degree, naturalism. And he will verbally deny that. But we saw that when we talked about stars taking a certain amount of time to get their current configuration, and therefore not being supernaturally created.

That's a form of naturalism. Yes, the debate is over presuppositions. And yes, if we had a panel of experts, they would be guided by their presuppositions. And so if you did have a debate and you chose the panelists, all of which are experts on astronomy and physics, by the way, most astrophysicists, most physicists, most astronomers are not Christians to begin with.

Most of them hold to the secular time scale. And that's because of their presuppositions. They are trained to look at the evidence in a particular way. But yes, the outcome of what they, you know, here's how we vote.

And we think this guy's the winner of the debate. But that doesn't really establish anything. The truth of the matter ultimately is established by God in the scriptures. Secondarily, written literature should give you a good guide as to who's in the right, at least when it comes to technical scientific issues, peer-reviewed literature.

And then you can at least investigate what are the presuppositions of the author? What assumptions is he making? Because in a research paper, you have to spell out your logic. You have to explain how you drew the conclusion that you drew.

And people can look at it and they can say, yeah, I agree with his data, but I disagree with that particular premise that he's using to draw the conclusion that he's drawing. That's why peer-reviewed literature is the way to go in discussing these kinds of technical issues.

The thing is, though, the conventionality thesis has been discussed in the peer-reviewed literature. It's just he Ross seems to not be aware of it. This issue has been, I won't say completely settled, but the majority of physicists certainly would agree with the conventionality thesis that the one-way speed of light cannot be measured by any experiment because it is a convention.

That's certainly what Einstein believed.

Well, Eli, what I'm bringing up is, if you're going to bring the level of debate to a technical area that's beyond what lay people can comprehend, it needs to be done in front of the peer-reviewed.

Peer-reviewed is written, at least if it's going to be rigorous peer-reviewed. Because again, you can get up in front of some experts and make all kinds of claims. And by the time you're done, they may not even remember all the claims that you've made, unless they're rigorously writing down, taking really good notes.

How can they immediately evaluate that in such a short time scale? Technical claims, a lot of times, require a great deal of thought, a great deal of research to investigate to see whether they're really correct, whether the conclusion really follows from the premises, whether the premises are true.

You need time to investigate that. You need time to look it up in journals and so on and so forth. That's something you can't do in a verbal dialogue. Hugh would not be able to get away with the claims that he's making right now in this dialogue in a written format.

He wouldn't be able to do it because he can make this claim that, well, these scientists have shown from supernovae that they've determined the one-way speed of light. Really show me the technical paper.

And he won't be able to do it because there aren't any technical papers that do that.

I checked.

If we want to talk about, you know, how do we interpret the Biblical Hebrew, let's do that in front of people that are fluent in Biblical Hebrew. If we want to talk about the astrophysics, let's do it in front of people who actually have PhDs in the discipline.

How about we do it in the written peer-reviewed technical literature? Because then I can reference the technical articles that have come before me that have demonstrated my point already, ones that Hugh is not familiar with.

See, in a dialogue like this, you can't do that. Everything happens too fast. You can't immediately refute your opponent because you don't necessarily have all the papers right in front of you. You don't know what he's going to bring up.

Whereas in a written exchange, you can. There's time. You can take a look at it. You can say, ah, I think he's bluffing here. And let me go to the paper and check. That's one of the reasons I wanted to follow up this dialogue with these comments because Hugh's made a number of claims that he really can't support, including this one, this idea that you can measure the one-way speed of light with a supernova.

You can't do it. And could I convince physicists in a small setting, in a very short period of time, in a sort of dialogue? Perhaps. But if I consult the peer-reviewed technical literature, then I can definitely make a good argument.

And like I did with Danny Faulkner, we actually agreed upon the astronomers who would be part of the adjudicating council. And so I'm prepared to make the same offer to Jason.

If Hugh is willing to do this in the written form, written exchange, then I accept. And I'd be happy to have some physicists look at it. And this, by the way, this is a physics issue, because we're talking about the one-way speed of light.

And I'm contending that Einstein was right, that it cannot be measured empirically, but rather is stipulated. Now, if Hugh wants to debate that, I'd be fine with that. I'd be happy to get some physicists together.

But let's do it in writing. So that everything's documented. And so you can't just make these claims out of the blue. All that, you know, that's, astronomers have proved that, have they? Show me the paper.

In a written format, that would be required. So Hugh, I hope you'll take me up on this and engage in a written debate on this issue. And I'm happy to look at it, have some other physicists look at it.

That'd be great. Hugh, the problem is what you're discussing has already been published in the secular literature. In fact, there's a rich history of debate on the conventionality of distance simultaneity throughout the 20th century.

If you want to see someone who tried to argue for it, for the position you're advocating, take a look at Malamud's paper. But that was refuted in 1999 by Sarkar and Stachel. So if we're going to dialogue about this, you're going to have to dive into the literature that's already been published in the peer-reviewed literature.

And if you want to publish a peer-reviewed article and debate online in a written format, I will happily do it on this issue.

No, I've looked at those papers and I agree with the comments that you're making there. What I'm saying is we now have observational evidence to put this to the test.

The papers that I cited demonstrate that there can be no observational evidence for a one-way speed of light because it's conventional. And so that suggests to me that Hugh either hasn't actually read those papers at all, or he read them and didn't understand them.

Because the fact is, if Sarkar and Stachel are right, if Einstein is right, if these others who have advocated the conventionality thesis are correct, there can be no observations that establish the one-way speed of light.

Can't be done. It's a convention. We choose it. It tells us how to synchronize clocks. Then we can measure one-way speeds. And the measurements that we get will be consistent with whatever we chose for the one-way speed of light.

And so the fact that we see these supernovae coming to us with different light paths, with different angles, they're not all coming directly towards the Earth, this actually gives us a way to test these ideas.

And this, again, is in the published literature.

No, it isn't. See, this is the kind of thing that Hugh can get away with in a verbal exchange, but he would not be able to get away with that in a written debate.

Why?

Because he would have to provide the reference. He would have to provide a reference to an article on supernovae that somehow try to prove the one-way speed of light. But the problem is there aren't any.

I've checked.

Remember, Hugh's been arguing about these gravitationally lensed supernovae. And these are relatively recent, right? 2014 was the first time any human being had seen that. And so you can look in the technical literature.

Are there any papers post -2014 that talk about gravitationally lensed supernovae and the speed of light? I've only been able to find one, and it said nothing, nothing about the one-way speed of light.

And so Hugh here is just bluffing is all it comes down to. Or maybe somebody told him that there was this paper that established the one-way speed of light from gravitationally lensed supernovae, and he just believed it.

But in any case, it's not true. So I'd like to take a look at this paper, and we'll see if Hugh is correct, or we'll see if I'm correct. So here's the paper, and it's testing the speed of light over cosmological distances, the combination of strongly lensed and unlensed supernovae, type 1a.

So let's have a look here. As we look into this paper in the introduction here, on the other hand, during the past two decades, great attention has been paid to the theories with varying speed of light, VSL, in which the speed of light might be dynamical and could have been varying in the past.

So this paper is not testing the speed of light in different directions. It's testing the possible differences in the round-trip speed of light over time. So it has nothing to do with the one-way speed of light.

Is the one-way speed of light even mentioned in this paper? Let's take a look. I can type down in here. I can type in one way, and no, it's not there. How about isotropic? Isotropic. Nope, it's not in the paper.

How about directions, as in different directions? Not there. So there's nothing about the one-way speed of light. You can measure the round-trip speed of light, sure, using supernova. That's not a problem.

We've been able to do that since, I mean, the first measurement of the speed of light is one of those that seems like it's a one-way measurement using Jupiter's moons, but in reality, it assumes the Einstein synchrony convention.

And so it's actually a round-trip measurement of the speed of light. So he was just mistaken on this issue. Again, that's something that he wouldn't be able to get away with in a written exchange.

Multiple papers have been written on the observation of the supernova eruption.

Not determining the one-way speed of light. They cannot do that. And even secularists will admit that. Secularists who are informed on this issue, like Sarkar and Stachel. You're going to have to look at those papers, Hugh.

Well, I do agree. It can't be done in a lab on planet Earth. But if you've got a distant supernova that's been gravitationally lensed, and the fact that they actually take different times to reach us.

It's perfectly consistent with the anisotropic synchrony convention. The light beam that takes the longer path, its angle is farther from line of sight, and therefore the speed of light in that direction will be slower than an angle that's closer to our line of sight.

And I gave that angle. I gave it in my original technical paper back in 2010. And then in my recent response to Peter and refuting the critics on our Biblical Science Institute website, I gave the formula again.

So again, Hugh has not bothered to read the literature on this topic, or he would know that what he's saying, it can't be done. You cannot refute a convention observationally. One of the things you may be missing, and by the way, have you read my article where I refute that?

Just out of curiosity.

I've not read your latest article. I'll take the time to do that. But again, have you read the articles on the supernova?

I have.

I have.

And what about these papers that Hugh says? Well, there have been multiple papers published on this gravitationally lensed supernova. Yes, I know I've read them. And they say nothing about the one-way speed of light.

You know why?

Because you can't measure the one-way speed of light using gravitationally lensed supernovae. And any physicist worth his salt would know that. Anyone who's familiar with the physics of Einstein would recognize that.

Let's have a look at these articles on this gravitationally lensed supernova. There are only a few because this happened very recently. So do these articles, do these technical papers support Hugh's assertion that they establish the one-way speed of light?

Do they even address the issue? Well, let's have a look. So this is one of the most recent papers analyzing these two gravitationally lensed supernovae, the only two that are known at the present time.

This paper was published in 2019. It deals with both the Revstow supernova and the more recent SNIPTF16GEU supernova. And it's using these to test cosmological parameters. That's the point, turning the title of the paper, turning gravitationally lensed supernovae into cosmological probes.

Because you can measure things like the Hubble constant by measuring the timing of these events. And so if there was any paper that was going to talk about trying to attempt to measure the one-way speed of light, this would be it.

So is there any mention of the one-way speed of light in this paper? Well, let's check. Let's do a search for one-way. One-way, click, not found. How about without the hyphen? One-way, not there. Well, how about the speed of light?

Let's try that. Even the speed of light is not mentioned. So obviously it's not going to address the one-way speed of light. How about isotropic? Well, that is mentioned, but it's regarding the magnification of the source.