How to detect changes in the laws of physics

I’ve been having an ongoing conversation with a YEC friend of mine, and he made me think of something interesting.

He frequently argues that God changed some of the physical laws/constants at various points. This is his way of accounting for the appearance of age (e.g. changing the speed of light to solve the distant starlight problem). When I point out that there is no evidence of this, he responds by saying that since we use the current form of the laws of physics to determine how things have changed over time, we wouldn’t be able to detect if the laws themselves had changed.

Normally, I agree for the sake of argument and simply respond that if he’s right about the undetectability of the changes, then his hypothesis is completely untestable and therefore just as valid as asserting the existence of an invisible intangible unicorn.

But then I started wondering: is it actually the case that a change in a law/constant would be undetectable? How would we detect such a change? My suspicion is that if some-but-not-all laws/constants changed, we should be able to detect it by triangulating the patterns it creates with that of two other patterns that normally agree, and looking for a sudden break in the 3-way agreement. For example, if tree rings, ice cores, and radioactive decay all agreed for a while, then suddenly only tree rings and ice cores agreed, that might indicate a change in radiometric decay rates.

What do you guys think?

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I think Jeremiah 33:25 applies.

This is what the LORD says: If I have not established my covenant with the day and the night and the fixed laws of heaven and earth

I am no physicist but I can think of one example. The spectral lines produced by a star are determined by the laws of physics. When you examine the light from those distant stars the spectral lines are just as the laws of physics predict. One of the constants in those laws is the speed of light so this is a good example of how the speed of light hasn’t changed. So there has been no change in the laws of nature since that light was generated. As the Bible tells us. God is constant.

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One of the arguments of fine tuning is that if the universe did not have the constants it has, it would essentially fall apart and be impossible for life and the present structure of the cosmos. While I may disagree some with their conclusions, I would agree that they are very correct on that point going by reading real physicist’s thoughts on the subject. So, if they were different, it would have been in a different universe.

Your friend seems to be holding to a version of the Texas sharpshooter fallacy, in which a bullet or arrow is shot at a barn, then the bullseye is drawn around it. In his case, he reached his conclusion, then looks for an explanation to justify it. On another post, the same problem is present with the Y chromosome DNA data of Jeanson.


Physicists do test for possible changes to physical constants. See
Time-variation of fundamental constants - Wikipedia and
Phys. Rev. C 74, 064610 (2006) - Natural nuclear reactor at Oklo and variation of fundamental constants: Computation of neutronics of a fresh core
for some examples.

That is precisely it. The thing that YECs overlook here is that the laws of physics aren’t just a collection of independent observations, facts and equations; they all have complex interdependencies, and if you were to change one of them it would end up having a knock-on effect on just about everything else. This means that you would have to change not just the speed of light, but all sorts of other constants as well, in complete lock-step with each other.

Furthermore, you aren’t just talking about minor tweaks to the physical constants. You are talking about rates such as nuclear decay changing by a factor of a billion at least, and that in complete lock-step with such things as continental drift, deposition of lake varves, tree rings, you name it. In fact, the YEC scientists themselves admitted that speeding up nuclear decay would have raised the temperature of the earth’s crust to more than 22,000°C, and that they couldn’t account for where all the heat could have gone by any known natural process. (Here’s a link to the page in their own report where they calculated the 22,000°C figure.)

It’s almost certain that getting any kind of lock-step out of changes to the physical constants would be mathematically impossible anyway. Changes to the fundamental constants of nature would affect different physical phenomena in different ways. Some things depend on the speed of light; some things depend on the speed of light squared, or on the square root of the speed of light, or even in more complicated, very non-linear ways. This being the case, if you tried accelerating two things A and B to remain in lock-step, you’d likely end up with something else, C, going completely out of whack in the opposite direction.

One example here is the creation of sedimentary rocks, such as shale, which form from tiny particles (typically a few microns in diameter) suspended in still or slow moving water which settle out over long periods of time. The rate at which sedimentary particles fall through water is given by Stokes’s Law:

v = \frac{2}{9}\frac{\left(\rho_p - \rho_{\rm f}\right)}{\mu} g\, R^2


  • g is the gravitational field strength (m/s^2)
  • R is the radius of the spherical particle (m)
  • ρ_p is the mass density of the particle (kg/m^3)
  • ρ f is the mass density of the fluid (kg/m^3)
  • μ is the dynamic viscosity (kg/(m \space s)).

Could you increase the rate at which they settle out by decreasing the viscosity? The problem with that is that you would end up increasing turbulence, which would disrupt the process and stop the shale from forming.


And as Werner Heisenberg apocryphally implied, even God doesn’t understand turbulence.


For me this fall into the “why would god try to deceive us?”
Their are many ways that God could have made the world the way it look today while imposing a 7 day creation time 6000 years ago. He could have made it to look like it 15 billion year old. What you friend suggests is also an option he could absolutely do this and in a way the we wouldn’t be able to detect.

The problem here is “why would he do this?”. It not like it can be oversight, which is in it self would be theological a can of worms, but we have multiple source corroborating to the age of the universe and the solar system. If the universe looks like it 15 billion years old and the solar system 5 billion years old, it is deliberate. If it is deliberate, their is only 2 possible explanation:

  1. the universe really is 15 billion year old and the earth is 5 billion and evolution happened …
  2. God is deceiving us, which would be an enormous can of worm to untangle. I’m willing to here out why he would deceive us but this would require and extraordinary and probably complexe explanation. At which point, if you succeed, I’ll probably invoke Occam’s Razor.

That’s kind of like the background noise that is always present. I once had a great convo with a guy who claimed to have been on a Nobel prize winning team in physics. He knew his stuff and I didn’t have any reason to doubt him based on what he said. He retired early, and I suspect it was do to his foresight into crypto. His memory was also getting bad, too much Whistle Pig I also suspected.

Either way, at a high point in the dialogue, he sarcastically lamented the heat death of the universe, to which I brought up quantum noise, to which he described recombination, to which I said, but still not an infinite number of events.

Even more of an issue is that the speed of light is inversely related to radiometric decay rates, through E=mc^2 defining binding energies.

I put forward the triangulation idea to him, along with the “it’s all connected” bit. Naturally, he disagreed with me. His main objection was that triangulation assumed our current understanding of science to show if science has changed.

This struck me as sort of true, and sort of not true. I think I can tease it out as a distinction between A) changing physical constants and B) changing physical laws.

A) If we’re trying to detect a change in physical constants, then we are indeed assuming the constancy of physical laws, and that doesn’t invalidate the method. We’re looking for changes in the size of the variables, not in the form of the equation.

B) But if we’re trying to detect a change in the laws themselves, that seems nearly incomprehensible to me. Asserting that we are wrong about the equations is one thing; asserting that they have actually changed is another. Given that physical laws are just mathematical descriptions of the relationships between physical properties, the only way those laws could genuinely change between two moments in time is if physical reality itself changed. For example, if “speed = distance / time” became “speed = 2x distance / time” or “speed = mass / time”. This just strikes me as absurd. At best, this is a untestable hypothesis with as much validity as the multiverse and invisible intangible unicorns. At worst, it’s just a nonsensical word game.

A is like adding another queen to a game of chess. B is like changing chess into checkers. Or at least that’s how it seems to me.


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It’s not true, period. Welcome to the wild and wacky world of how YECs are taught to think.

What your friend is doing here is trying to use the concept of “making assumptions” as if it were some sort of magic shibboleth or get-out-of-jail-free card that allowed him to hand-wave away anything that he didn’t like. YECs are taught to think like that, and they tend to repeat it over and over again like a record stuck in a groove when they can’t figure out what else to say. But assumptions don’t work like that. Triangulation – or cross-checks, or consilience – does not make assumptions; on the contrary, it tests assumptions, and tests of assumptions are not assumptions themselves.

And no, your friend can’t wriggle out of that one by claiming that they are just “assumed” to be tests of assumptions. Here’s why: in order to challenge a scientific theory on the grounds of assumptions, he needs to do three things:

  1. State exactly what the assumptions are.
  2. Make sure that the theory really does make the assumptions that he is claiming that it makes.
  3. Provide a coherent explanation as to how the assumptions could have been violated in such a way as to give the exact end results that we actually observe, right down to the precise measurements.

Anything less than that is basically making things up and inventing one’s own alternative reality. In other words, lying.

This is where your friend’s argument falls down. In order to justify a young earth, he needs to come up with a coherent explanation as to how millions of measurements over the past hundred years – many of them with error bars of less than one percent – could all not only be wrong, but could all end up giving the same set of wrong answers as each other, despite coming from a wide variety of different methods and a wide variety of different fields of study. Being wrong simply does not work like that.


Yeah, I’m aware of the YEC “assumptions” game, being a former YEC myself. But to play devil’s advocate for a moment…

I’m curious what you think of my scenario (A) above. For example, let’s say we have 2 points, A and B, and a distance D between them. If we wanted to detect the value of D without measuring directly, we could use the equation for velocity (v = d / t), measure our velocity V and time T, and conclude that D = VT. If we tested over and over with the same V, and eventually A and B moved farther apart (increasing D), we notice this because it took us longer (T) to travel.

The assumption in this scenario is that velocity = distance / time, and that this equation never changes. If that assumption is false, the scenario doesn’t work.

Am I right about that?

@danielrbaughman , I wonder what your friend’s standards for interpreting past events are. Has he used the you weren’t there to see it card? There’s little reason that you alone should be left to muse on his assertions if he makes a claim that doesn’t meet the scrutiny of his own standards.


This is chasing the horizon. How do we even know physical law is general in the here and now? Even with millions, billions, or trillions of measurements, when we are not looking what we perceive as the material world could mock us. Given sufficient skepticism, even I think therefore I am can be cast to doubt, and you are at an impasse. It is all an illusion, prove me wrong. If physical reality is rational however, changing physical constants and laws are extraordinary claims, and without compelling evidence such can be summarily dismissed.

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Since we know of many characteristics of nature that aren’t constant it seems rather obvious that we can measure change in a measurement over time. For example, how do we know that the density of water changes with temperature? According to your creationist friend, we shouldn’t be able to measure this change.


Are you ‘asking for a friend’?

The danger with that formulation is that some will run away with the fairy that radiometric decay is causal of the speed of light, even though she isn’t there.

It’s not an assumption. Velocity (or, more strictly, speed) is defined as distance over time - that’s what it means, its units are unit-of-distance per unit-of-time, e.g. metres per second.

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If I understand the physics correctly, the speed of light is itself an effect of deeper properties of nature which are the permittivity and permeability of the medium that light is travelling through.

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