Let's assume they manage to make a nuclear clock out of this, with an Allan drift that's low enough to be useful. Once that's done, it'll take years of observation to measure any meaningful differences and gather enough data to notice something.

Meanwhile, moving the height of anything a centimeter, the position of the moon, and a whole other host of noise sources have to be canceled out.

I have no doubt this will be done... and it will be awe inspiring to hear it all told after the fact.

While you're waiting... I found this really cool meeting documented on YouTube[1] that has the clearest explanation of how Chip Scale Atomic clocks work I've ever seen.

I look forward to Chip Scale Optical Lattice clocks

[1] https://www.youtube.com/watch?v=wHYvS7MtBok

> Lots of nuclei have similar spin transitions, but only in thorium-229 is this cancellation so nearly perfect. > > “It’s accidental,” said Victor Flambaum(opens a new tab), a theoretical physicist at the University of New South Wales in Sydney. “A priori, there is no special reason for thorium. It’s just experimental fact.” But this accident of forces and energy has big consequences.

...

> Physicists have developed equations to characterize the forces that bind the universe, and these equations are fitted with some 26 numbers called fundamental constants. These numbers, such as the speed of light or the gravitational constant, define how everything works in our universe. But lots of physicists think the numbers might not actually be constant.

Putting these things together, if the physical constants do change over time, then perhaps there really isn't anything special about thorium-229, it's just that it's the one where the electrical repulsion and strong nuclear forces balance out right now. In a billion years maybe it would be some other element. Maybe we're just lucky to be alive at a time when one of the isotopes of an existing element just happens to line up like this.

Perhaps too there's an optimal alignment that will happen or has already happened when those forces exactly balance out, and maybe that would be an ideal time (or place, if these constants vary by location) to make precise measurements in the changes to these constants, much like a solar eclipse was an ideal opportunity for verifying that light is bent by gravity.

  These numbers, such as the speed of light or the gravitational constant, define how everything works in our universe. But lots of physicists think the numbers might not actually be constant.

Maybe that would explain all the missing 'dark matter', or even provide an alternate explanation as to why so many species on our planet were larger millions of years ago (assuming an explanation for these two phenomena isn't self-contradictory, which, given my lack of physics background, it might well be!)

The article mentions 26 constants but it seems there is more than that https://en.wikipedia.org/wiki/List_of_physical_constants

And I think if the constant is a ratio, like the fine structure constant, https://en.wikipedia.org/wiki/Fine-structure_constant no change can be detected, even if there were a change because the ratio will stay the same. Likewise a constant like pi will stay the same because it is a ratio.

This always seems like a logical error to me and perhaps someone can explain:

To measure a constant, you need something constant, but you do not know if something is constant if you do not have something constant to measure it against. (False premise?)

I believe we can only assume things are constant, but they only appear constant.

I you read the work of the physicist Julian Barbour regarding time I think you will be in for some remarkable insights. "Time arises out of change".

https://www.youtube.com/watch?v=GoTeGW2csPk

Matter in other galaxies would behave differently from matter in the Milky Way if fundamental constants are not always true. I argue about this sometimes. Others keep stating that the wavelengths are equal, so everything else must be.

If fundamental constants could change, this would violate energy conservation, and the second law of thermodynamics. Someone once said, if your pet theory violates the second law, there is no hope. Or am I missing something?

It’s still something of an open question whether or not G is actually constant.

Not only that, but the results differ depending on whether atomic or dynamical time is used! In the latter case no change is measured using lunar reflectors.

Possibly a dumb question: How do you determine the accuracy of the most precise clock? You don’t have anything more accurate to measure it against, right?

I think you might mean the one _electron_ conjecture. It’s fun because you have anti-electrons whose Feynman diagrams look like electrons going backwards in time. So you could conceivably be observing the tangled world line of a single electron bouncing back and forward in time — sometimes observing it as an antielectron.

Doesn’t work with photons because there’s not an anti-photon.

Anyway it’s sort of a fun “woah!” moment that Feynman was so good at producing, but I don’t think it’s taken particularly seriously as a theory.

If the laws of physics can drift over time, might that explain the Big Bang?

Maybe Boards of Canada was right, and constants are changing.

Seems like a case of premature naming to me! If we have to test whether or not they change, they shouldn't already be called "constants".

If it does change, for what ever reason, like, what does it actually mean?

Someone big brain explain to me why this is a big deal.

this is mind blowing to see

"When you absolutely, totally, fundamentally, have to, fundamentally be sure" :)

They probably do change, but extremely slowly. It would feel strange if there were something fixed in the universe.