The First Nuclear Clock Will Test If Fundamental Constants Change
The first nuclear clock, developed using thorium-229 nuclei, offers unprecedented precision and sensitivity to fundamental constants, potentially revealing variations in the laws of physics over time.
Read original articleThe recent development of the first nuclear clock, based on an ultra-precise measurement of a transition in thorium-229 nuclei, marks a significant advancement in physics. This breakthrough, achieved by a team at JILA in Boulder, Colorado, allows researchers to probe the fundamental forces of the universe. The thorium-229 nucleus exhibits a unique property where the energy required to excite it is remarkably low, making it sensitive to changes in the fundamental constants of physics. This sensitivity arises from an almost perfect cancellation of two of nature's forces within the nucleus. The measurement, reported in the journal Nature, is millions of times more precise than previous attempts and opens the door to investigating whether the laws of physics vary over time, as suggested by various theoretical frameworks. The thorium-229 nuclear clock could provide insights into the constancy of fundamental constants, which are crucial for understanding the universe's behavior. The research team, led by graduate student Chuankun Zhang, celebrated their achievement, which is seen as the beginning of a new journey in fundamental physics.
- The first nuclear clock has been developed using thorium-229 nuclei.
- This clock is sensitive to changes in fundamental constants due to unique properties of thorium-229.
- The measurement is significantly more precise than previous attempts.
- The research could help determine if the laws of physics vary over time.
- The development is viewed as a major milestone in experimental physics.
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- Many commenters express skepticism about the idea of constants being truly constant, suggesting they may change over time.
- There is a discussion about the challenges of measuring these constants accurately, including the need to account for various noise sources.
- Some commenters highlight the philosophical implications of changing constants, questioning the nature of measurement and reality.
- Several users reference the significance of thorium-229 in this context, noting its unique properties that make it suitable for precise measurements.
- There is curiosity about the broader consequences of changing constants, including potential impacts on our understanding of the universe and fundamental physics.
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
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> 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.
In my ignorant, non-physicist head, gravity always struck me as a force that would make sense as variable.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!)
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.
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".
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.
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.
Someone big brain explain to me why this is a big deal.
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