If the speed of light is anisotropic, the age of the universe is even older than given an isotropic speed of light, because distant starlight is slower from one direction. An average value yields the youngest possible age.
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You’re correct that the one-way speed of light cannot be measured and that synchronization conventions are arbitrary - that’s not the point, and I’m not disputing that.
But here’s the key distinction you’re missing: the distant starlight ‘problem’ for YEC isn’t just about the one-way speed of light, an interesting, but very tangential to the bigger issue. It’s about what we observe when that light arrives, regardless of how fast it traveled.
Let me use an analogy: Imagine you receive a letter that describes events happening over several years - births, deaths, construction projects, etc. The ‘speed’ the letter traveled to reach you doesn’t change what’s written in it. Similarly, light from distant objects carries information about processes and events, not just the fact that the objects exist.
When we look at distant supernovae, we see the explosion happening - the brightening and dimming over months. Supernova which took tens of millions of years to run out of fuel… and tens of thousands of years to collapse into stars in the first place. When we observe Cepheid variables, we see them pulsing with specific periods. We see galaxies colliding and merging. We observe the afterglow of gamma-ray bursts fading over weeks. We see globular clusters with over 10 billion years worth of stellar evolution.
So even if light traveled instantaneously, we’d still be seeing processes that require vast amounts of time to occur. The one-way speed of light doesn’t solve this fundamental issue.
The CMB temperature-redshift relationship I mentioned earlier is another example. Even if that information arrived instantaneously, it still tells us about a universe that was hot 13.8 billion years ago and has been cooling ever since. The physics of that cooling process is what determines the temperatures we measure at different redshifts.
Another fun example is Galaxy ESO 137-001, which is a Galaxy being gravitationally pulled the upper left of this picture:
Fine, speed up light infinitely fast in one direction, but I ask, how long does it take to pull an entire galaxy 260,000 light years??? It definitely happened, so again, even if the light got here infinitely fast (yet still averaged to ‘c’), this is the bigger problem for the young-earth creationism perspective. The universe looks old… really really old…
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No, the justification is that the appellation is objectively true.
I do, too, but he isn’t lying because he is applying legitimate tools he learned in his studies. That he goes ridiculous places with them is not lying, it’s just inane. Lisle is deliberately contradicting things he could not have gotten an astronomy degree without knowing.
The issue is that Muller has defined the issue narrowly enough that the problems with it are set aside. If all you look at is the velocity aspect, yes – the one-way speed of light cannot be measured. But that leaves aside all sorts of other issues that say that the speed of light is constant, one way or two.
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Again, I could say the same about Elaine Pagels or Bart Ehrman, among many others. How can one be a chair-holding New Testament scholar, and write a book about Revelation, and make such an utterly asinine and laughable claim as the author of Revelation "doesn’t even say Jesus died for your sins”… Which is contradicted in the first six verses of the book under discussion. How can this chair of New Testament at Princeton University contradict something set a seven-year-old could know simply by reading the first chapter of the book of revelation?
I believe I have, in the past, made a statement as bold as something to this effect… “"She is either flat out lying to push her preferred narrative, or she is simply grossly and laughably incompetent, so wedded to her preferred narrative, that she can’t see that her claim is contradicted Throughout the book of revelation, including in the first six verses of the book. Charity demands that I assume the latter.”
I could say the same about Ehrman… In order to maintain his pet theory (his “exhibit A”) about the gospels contradicting each other, he claims they conflict over the day Jesus was crucified…. Thus he spends pages arguing that the “day of preparation" in John’s Gospel refers not to the day before the Sabbath, but the day before the Passover… A claim which could be contradicted by any 5th grade Sunday school student who simply bothered to read the crucifixion account in the Gospel of John.
I could accuse Ehrman of lying, but again, Lacking any actual evidence of this, charity demands that I simply accuse him of being utterly and grossly incompetent, so wedded to his narrative that he could not be bothered to notice facts that would be obvious to a child that would conflict with his pet theories. But Even as asinine and imbecilic as his claims are about topics in a field where he is a supposed expert - a chair-holding professor at Duke - claiming for him to be intentionally lying is still simply uncharitable; Short of actual evidence that he is intentionally lying, Charity demands that I assume instead that he is merely grossly incompetent and utterly dim witted.
No, short of someone possessing clairvoyance and reading his hidden motives, it is not “objectively true”. One can be completely erroneous, and make a statement that is proven to be false, without deserving the appellation of being a “liar.”
if you are right about the data and his errors, then one could still conclude (as I do about the like of Ehrman and Pagels) that Lisle is utterly and laughably incompetent in his field, so wedded to his preferred narrative that he is able to make absurd claims where he should know better, as they could be easily contradicted by any neophyte in his field.
But unless you magically can read his heart or have the clairvoyance to know his hidden motives (or know of some “smoking gun” actual evidence where he directly admits to lying), then I still maintain that charity demands that you can at most claim someone to be grossly incompetent.
Straight up claiming someone to be lying, and especially of assigning them a cutesy alliterative pejorative epithet to that effect, seems to me uncharitable in the extreme. Especially to someone who is presumably a brother in Christ, whatever differences one may have of his view of origins. Accuse him of being so married to his young earth creation narrative that he is utterly blind to patently obvious facts that would contradict his theory, fine. But to accuse him straight up of breaking the ninth commandment?
But again, I know very little of his specific claims, or the supposed conflict between his ideas and the critiques of his detractors. I was just discussing the Veritasium video.
But I must say that whenever – in any context – I hear people making such similar accusations, and simply accusing someone of lying, rather than actually critiquing his errors… It makes me immediately sympathetic to the accused…. When i start to feel like “The detractors doth protest too much...” It makes me begin to think that maybe their opponent has something after all, If they prefer insults to argumentation. If you are correct, that many people are tossing around this pejorative sobriquet about him, this actually makes me all the more interested to hear him out.
Matthew, there is no “distinction” I am missing… as I was not discussing (and have no interest at present in discussing) those bigger issues you mentioned, any more than Derek Mueller was missing this “key distinction” in his Veritas and video. The one-way speed of light was all I was interested in discussing. I am quite aware of those and plenty of other challenges to YEC Including those you brought up, But none of that was relevant to my present observation.
My only observation that I was posting about was merely and strictly about distant star light reaching the Earth, as I had always assumed this to be, de facto, a direct, straightforward, and insurmountable problem for the basic YEC position: if the Andromeda galaxy is 2.5 million light years from earth, then the light from said galaxy must have taken 2.5 million years to get here, end of discussion… and thus the universe would have to be at least that old. And then we could keep going for more distant galaxies. I had always assumed this to be a direct, obvious, and rather insurmountable challenge to the young earth position.
All I was observing in this post was that, given Derek’s observation in his Veritasium video that we could be looking at Mars immediately, as it is right this moment, as well as other stars, that this single, limited and specific so-called problem for YEC simply doesn’t seem to be a problem at all. it is not the problem for young earth creationists that I thought it was. This was all I was observing.
I was making absolutely no other claims or observations whatsoever about any other related, tangential, or ancillary issues in cosmology or astronomy, nor any claims for or against YEC, so there is no “distinction” I am missing.
Point is, that is the point. And as the one who made the original post, I think I have some warrant for claiming to know what the main point of this discussion is…?
What’s more likely and by how much? That the earth is flat, or an oblate spheroid? Taking all science and reason in to account?
Where are the errors here?
No expert is necessary to c that “c” actually is defined or otherwise understood empirically to be both the one-way and two-way speed of light, as the one-way is undefined due to lack of clock synchronization. Any competent mathematician can comment on undefined values, as they do upstream. Unless indeterminate can’t mean undefined?
And why does one have to ‘theologically’ believe that this incoherent, unwarranted, unjustified, untrue belief, according to the divine invitation to reason, is nonetheless coherent, warranted, justified and true, beyond reason?
Could there be a psychological reason?
If Genesis didn’t exist, would it be necessary to invent it?
and exactly why I posted what I did, which was the point…
Before watching the Veritasium video, I would have wholeheartedly agreed with @T_aquaticus in his critique here… it is an observation I myself used in the past… if we are seeing a supernova 160,000 light years away, then, de facto, the light from that supernova took 160,000 years to get here, end of discussion… And if this is the entire universe were merely 6000 years old, then we are seeing a false and essentially deceitful image: light that God apparently put in transit to the Earth from a star that never existed in the first place… Including a visual record of an explosion that never happened.
But given what I discovered from Veritasium (www.youtube.com/veritasium), I now recognize that this entire line of argumentation is simply null and void. If, as Derek observed, “you could see stars hundreds of light years away, not as they looked centuries ago, but exactly as they are right at this instant…” then we could be seeing that supernova 160,000 light years away, not as it looked 160,000 years ago, but exactly as it is right at this instant.
Thus, all lines of argument against the young earth position that depend on light from distant stars and galaxies taking significant time to reach earth (including the one noted above about observing a distant supernova) simply become null and void, and essentially irrelevant.
(And to clarify, as this point was apparently missed earlier… I’m not suggesting that there are not a plethora of other data or arguments that can be amassed against the young earth creationist position…. I’m simply and solely recognizing that those specific arguments that depend on light from distant stars taking significant time to reach earth cannot be included in them.)
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(I thought I had responded to this earlier, but perhaps I forgot to actually post it, please forgive me if im repeating something).
I certainly see your point, but I am afraid I am simply to uninitiated to know one way or the other about these specifics, so I will have to withhold judgment for the moment
To simplify your illustration (at least this simplifies it for me), let me imagine I am standing in between your two photon emitting gunslingers, and they are both aiming directly at me…. One is to my east, and the other immediately opposite to my west…. and they both fire beams of light at me simultaneously….
It certainly seems straightforward, and common sense, that if, say, The gunslinger to my east fired a beam of light at me, and its one-way speed was instantaneous, that this would obviously mean that the light fired by the gunslinger to my west would be approaching me at c/2.
Yes, this seems absolutely straightforward, common sense, and obvious to me. Problem is, I have learned that absolutely nothing conforms to what i think should be straightforward, obvious, or common sense when discussing topics around relativity, the speed of light, or quantum mechanics, and how much the “observer” impacts the whole mess.
For instance, when we start invoking relativity, what does it even mean if I claim that both gunslingers fire at me simultaneously? I can’t know that, as I would need to be observing them when they fire, and that information would take the speed of light to get to me… not to mention that one observer might witness them pulling their triggers simultaneously while observers in different reference frames or at different speeds might witness one or the other pulling their trigger first.
I am too uninitiated to know one way or the other about this… that if I’m looking at the gunslinger to my east, and stipulate that the light I’m observing from the east approaches me at ∞, then must I de facto conclude that light hitting the back of my head from the gunslinger to my west is thus approaching at c/2? Again, this would seem instinctive, straightforward, and common sense to me.
But also again, I just don’t trust anything to be instinctive, straightforward, or commonsensical when relativity is involved. if all sorts of things in relativity change depending on what the observer is doing or where he is, and if the one-way speed of light is as arbitrary or undefined as Einstein seemed to suggest, and can be stipulated to be whatever the observer desires within certain limits…
Then what prevents me from turning around, looking at the gunslinger to my west, and “stipulating” (to use Einstein’ language) that the gunslinger to my west is shooting light at me at ∞?
I really do sympathize, and I am inclined to agree with you: it just seems obvious and common sense that, given light’s confirmed two way speed of c… that if I am stipulating that the light approaching my face is travelling at ∞, then the light hitting the back of my head must be approaching at c/2. but as I said, I am too uninitiated and ignorant so much of these details to know whether what seems common sense actually works when relativity is involved, and if the one-way speed of light is a stipulation, if there actually is anything in the mathematics that prevents me, as the observer, from turning around and stipulating different one-way speeds of light for different directions.
So Derek is infallible and you will take his word over the rest of the physics community. Got it.
I absolutely agree that we haven’t measured the one way speed of light. That doesn’t mean light travels at any speed we choose.
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Derek is wrong. I have given you multiple articles from physicists clearly stating that light can’t travel instantaneously.
Stephen Reucroft and John Swain, professors of physics at Northeastern University in Boston, Mass, provided the following explanation:
. . .
The previous two arguments are two slightly different ways to say that if you think light is a wave, then it has to be something that propagates and takes time to go from one point to another. In other words, it has to travel at a finite speed. Infinite speed of propagation is an instantaneous magical change in things everywhere all at once, and not a wave at all!
Why isn't the speed of light infinite? | Scientific American
Light is a wave. We can measure it.
In physics, we’re more concerned with constants that have no units or dimensions — in other words, constants that appear in our physical theories that are just plain numbers. These appear much more fundamental, because they don’t depend on any other definition. Another way of saying it is that, if we were to meet some alien civilization, we would have no way of understanding their measurement of the speed of light, but when it comes to dimensionless constants, we can all agree. They’re just numbers.
One such number is known as the fine structure constant, which is a combination of the speed of light, Planck’s constant, and something known as the permittivity of free space. Its value is approximately 0.007. 0.007 what? Just 0.007. Like I said, it’s just a number.
So on one hand, the speed of light can be whatever it wants to be, because it has units and we need to define the units. But on the other hand, the speed of light can’t be anything other than exactly what it is, because if you were to change the speed of light, you would change the fine structure constant. But our universe has chosen the fine structure constant to be approximately 0.007, and nothing else. That is simply the universe we live in, and we get no choice about it at all. And since this is fixed and universal, the speed of light has to be exactly what it is.
[emphasis mine]
In order for the speed of light to be any other speed that c in any direction, one way or two way, you would need to change the most fundamental constants in the universe.
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The one way speed of light isn’t undefined, it just isn’t directly measurable. However, we can determine the consequences of light travelling instantaneously in one direction, and those consequences aren’t seen in experiments where they should be observed. For example, we shouldn’t be able to measure light’s frequency if it is travelling instantaneously, but we can. We also understand the physical constants that undergird the speed of light, and those constants are just that, constant.
All Veritasium has done is highlight the difficulty of measuring the one way speed of light which is a consequence of relativity. This, in no way, indicates that light is travelling instantaneously in any direction.
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I’m taking Derek’s word for it because the rest of the physics community seems to completely and totally concur with what he is saying at this point. Is there any physicist that you might point me to that is seriously disputing Derek’s claims in this particular video?
Well, as I hardly claim to be an expert on this topic, maybe you can try to convince Matthew @pevaquark … as he seems to concur with Derek and all other modern physicists on that point, that synchronization conventions are indeed arbitrary and thus the one-way speed of light cannot be defined, empirically or otherwise, as c, but rather that c is simply a freely-chosen convention and one is free to choose otherwise within certain limits. If you can convince him (since he seems to have more working knowledge than I do), then I may reconsider your objection?
(emphasis mine).
But again, if you’re so sure that you have demonstrable proof that the one-way speed of light is indeed c based on such observations as being able to measure its frequency, or that it objectively cannot be anisotropic after all… then I’d encourage you to write up a paper demonstrating this… I suspect you would be likely to win a Nobel prize for thinking of something that no physicist since 1905 has ever thought of! But until you can convince the entire physics community to change their view of something that they have held pretty unanimously since the time of Einstein, I’ll defer to Einstein and the rest of the community.
By the way, you do recognize the multiple logical fallacies in this one response, no?
The question really is to what extent we should assume good faith. We had a discussion about that question a couple of years back.
As a general rule, I think it’s reasonable to expect people to make sure their arguments are consistent with their general level of education and experience. If a PhD astrophysicist is making claims that fly in the face of GCSE-level maths, for example, that is not something I would consider even remotely acceptable and for that a designation of “lying” would be appropriate. On the other hand, an arts or humanities graduate would warrant somewhat more leeway. They have ignorance as an excuse. PhD astrophysicists do not have that luxury.
There is one confounding factor though. There are some Bible verses that talk about God choosing the foolish things of the world to confound the wise (e.g. 1 Corinthians 1) and it’s quite common in some Christian circles to read those verses as if they were some sort of anti-intellectual manifesto. It’s not uncommon for people with a background in science or engineering to start viewing their technical background as something that gets in the way and causes them to start “overthinking” things. Personally I think such people are missing the point of these verses—they’re about people who lack an education through disability or discrimination, not about lowering your intellectual standards by choice—but people who get into that way of thinking can easily end up in a mindset where they think they’re acting in good faith when they are regurgitating arguments that they should otherwise be reasonably expected to know to be patent nonsense.
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They’re not. The physics community completely disagrees that light travels at anything other than c, in any direction, one way or two.
YES!!! I’ve cited two of them twice.
You are once again confusing two things.
- We can’t measure the one way speed of light without using a convention.
- Light is travelling instantaneously.
Those are NOT the same thing. @pevaquark even wrote a post detailing why light can not be travelling at an infinite speed in any direction, one way or two.
Suppose that this light could “shoot” here instantaneously fast because of a technical possibility in the mathematics of some equations. Well, it just so happens that the further away it is, the background temperature gets hotter, as measured from the Sunyaev-Zeldovich effect.
Put another way, we measure the CMB temperature to be 2.7 K today, and when it was first formed in the early universe, its temperature was around 3000 K. So in principle, if we measure the CMB temperature of distant objects (or those with higher redshift), it should be hotter than today, but not as hot as when it first formed.
So…. the CMB photos from the distant objects (billions of light years away) match what we would expect with the measured expansion of space, assuming the speed of light traveled at one light year per year. Which brings me to another point, if light travels instantaneously fast, it cannot explain the CMB at all or the redshift of light from distant galaxies. Instantaneous travel does not produce any redshift at all because the redshift comes from the actual wavelength being stretched slowly by the expansion of space itself.
I already gave you an article written by a physicist who said that very thing.
Name the logical fallacy.
The only person committing a logical fallacy is you. You are claiming that if Veritasium is right about one thing then he is right about everything. You are also determining the accuracy of physics by youtube video views.
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Appreciate the thoughts, but I’d have to respectfully differ. The examples I gave I think are instructive on that point… Elaine Pagels is a chaired professor of religion at Princeton and was writing a book about the biblical book of Revelation. Claiming that the author of said biblical book “doesn’t even say Jesus died for your sins” is not just wrong, it is absurdly wrong, on the level of claiming that Jesus wasn’t an important figure for the author of Luke. Besides the concept appearing throughout the book, it is explicitly affirmed on literally the first page. One wonders if she cracked open the Bible even once before writing her book. She has absolutely no excuse for the level of ignorance required to make such an error. Bart Ehrman, similarly, has no excuse for the stunning levels of ignorance he exhibits while he pushes his demonstrably false claims.
I could name others, but these two stand out as the most egregious examples I have read. They have absolutely no excuse for pushing demonstrably false claims while claiming to be an expert in areas where they are so obliviously ignorant of obvious, basic facts. I find it reprehensible.
but even so, I simply can’t bring myself to straight up accuse them of lying. that is a serious accusation and requires that I know their heart. Sometimes, admittedly, I really wonder if Bart Ehrman actually knows better and is flat out lying to maintain his pet theories. But the point remains that I have no evidence of his heart motive, nor any other tangible evidence that he is intentionally lying. so charity still demands that i take the more charitable interpretation, that being he is inexcusably ignorant and embarrassingly incompetent due to being so wedded to his pet narrative that he can’t be bothered to look at actual facts. I’m willing to say that, but I simply can’t take the step to accuse him of lying.
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Why Gravitational Lensing Constrains Synchronization Conventions
I appreciate you clarifying the scope of your observation about the one-way speed of light and distant starlight. Again, yes, Derek’s video accurately presents the physics of synchronization conventions, and that we cannot directly measure the one-way speed of light.
However, I think there’s a significant constraint on non-standard synchronization conventions that wasn’t addressed in the original post: gravitational lensing observations.
The Deja Vu Supernova Case
Take the famous “Deja Vu” supernova (SN Refsdal), discovered in 2014. This supernova appears multiple times in our telescopes because its light takes different paths around a massive galaxy cluster due to gravitational lensing. The supernova had previously appeared in locations S1-4 and researchers were predicting it would appear in a new location ‘SX’ due to gravitational lensing and the speed of light.
Here’s what makes this relevant to the synchronization discussion:
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What we observe: The same supernova explosion appears as multiple images that arrive at different times. We can predict when subsequent images will appear based on the geometry of the lensing system and the assumption that light travels at constant speed c in all directions.
The prediction vs. reality: In 2015, astronomers successfully predicted that another image of the same supernova would appear in late 2015/early 2016 - and it did, right on schedule.
Why This Constrains Synchronization Conventions
Here’s the key issue: if light traveled infinitely fast toward Earth (or at some other non-standard speed), then all the lensed images should arrive simultaneously, regardless of the different path lengths around the galaxy cluster. But that’s not what we observe.
Instead, we see time delays between the images that perfectly match calculations assuming light travels at speed c along each curved path. The longer paths produce later arrivals, exactly as expected.
There are many of these such images throughout the galaxy, with a fun prediction of a different deja vu supernova’s reappearance in 2037!
The Network Effect
What makes this even more constraining is that we have many such lensing systems, creating essentially a network of light paths crisscrossing the universe in different directions. Each system provides multiple constraints on the speed of light in different directions simultaneously.
For a non-standard synchronization convention to work, it would need to be fine-tuned in an incredibly contrived way to reproduce all these observed time delays across all these different systems and directions. Here’s a paper outlining many of the multiple lensed objects we expect to see in the next ten years: https://royalsocietypublishing.org/doi/10.1098/rsta.2024.0134
Independent Confirmation
We can also independently measure the geometry of these lensing systems using:
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Weak lensing measurements
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Galaxy velocity dispersions
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X-ray observations of hot gas
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Computer simulations of structure formation
These confirm that the path lengths are indeed what we calculate them to be, making the light travel time predictions even more robust.
The Broader Point
While synchronization conventions remain mathematically valid for simple point-to-point scenarios, gravitational lensing creates a web of interconnected constraints that severely limits how exotic these conventions can be while remaining consistent with observations.
So even focusing narrowly on light travel (as you’ve chosen to do), the universe provides us with natural experiments that effectively triangulate the speed of light in multiple directions simultaneously.
This doesn’t invalidate Derek’s video - he’s correct about the fundamental principle. But it does suggest that the observational constraints are much tighter than a simple Earth-to-star scenario might imply.
And all of this ignores all of the information contained in the light about how our universe is very old.
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To use an analogy:
Hank: When my wife goes in the bathroom I can’t see what she’s doing in there. No one can see through the door. Since I can’t know what she is doing, then she could be doing anything. Therefore, I claim that my wife is exploding a thermonuclear device in the bathroom while I can’t see what’s going on.
Sam: Umm, Hank, you wouldn’t need to know what was going on inside the bathroom if a thermonuclear device went off in your bathroom. There would be obvious evidence if that were the case.
Hank: You’re wrong, Sam!!! Prove me wrong by trying to look through the bathroom door while my wife’s in there.
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With regard to the first chapter, Ehrman is technically right – but he’s playing word games, really, to avoid the fact that “freed us from our sins by his blood” implies death. It’s a cheap trick to entice people’s attention.
Lisle’s deception doesn’t even rise to the level of word games – he flat out contradicts things impossible not to know for anyone with even a bachelor’s in astronomy.