A planet in orbit, or a spaceship like Voyager travelling through the galaxy, is in perpetual motion, but if you try to harness that kinetic energy, you'll slow it down.

In a way, the quantization of reality at very small scales does appear to prevent the laws of thermodynamics from occurring. This is just one form of Zero-Point Energy[1]. Maybe these time crystals are another form - maybe some large objects radiate some kind of time-entropy, and these are too small (or configured in some other way), such that they are also mechanically prevented from doing so?

IANA theoretical physicist - I merely play one on the internet. Expert opinion and advice is welcome.

[0]https://physics.stackexchange.com/questions/18473/where-do-e...

[1]https://en.wikipedia.org/wiki/Zero-point_energy

> Niels Bohr proposed that electrons don't have enough energy to radiate away, and thus are forced to continue to spin around the nucleus.[0] This was the seed that fruited the quantization of energy and eventually our modern understanding of Quantum Mechanics.

The first sentence is correct, though the history directly begins in 1900 with Planck's quantization hypothesis in the context of black body radiation. Bohr's paper, which I assume you're referring to, came in 1913.

> In a way, the quantization of reality at very small scales does appear to prevent the laws of thermodynamics from occurring. This is just one form of Zero-Point Energy[1]. Maybe these time crystals are another form - maybe some large objects radiate some kind of time-entropy, and these are too small (or configured in some other way), such that they are also mechanically prevented from doing so?

I do to take an issue with this paragraph, in that it doesn't really map to any well defined concepts in modern physics. The "quantization of reality at very small scales" (by which I assume you're referring to the speculative idea of fundamentally quantized spacetime) doesn't really have anything directly to do with thermodynamics - the laws of thermodynamics are necessarily statistical laws, produced by the behavior of ensembles defined by particular distributions. They have no particular validity in (most) very small scale systems and I don't see how the quantization is relevant here. Nor do any of these remarks help you violate the conservation of energy with respect to any larger systems.

I have no idea what "time-entropy" means, but generally speaking this notion of time crystals doesn't have anything intrinsically to do with violating energy conservation or producing useful work (in the physical sense) in any new fashion. Rather, it represents a fairly ingenious way of applying the established mathematical tools of analyzing symmetries to systems that exhibit complex periodic behavior rather than just spatial symmetries. In that regard, I think the example of satellite motion presented by Latham Boyle [1] was very illustrative without being misleading or overly suggestive.

I hope this response isn't overly snarky, I just wanted to clarify a few misconceptions I've seen a lot in the last few days.

[1] https://arxiv.org/abs/1407.5876

This is the fundamental reason why electrons can't orbit the nucleus in a classical sense (and why we know the Bohr model is incorrect). The atom is a quantum object and as such it does not behave in a classical manner. You can describe it heuristically as an electron 'orbiting' the nucleus but that is not what's actually happening. The very concept of a path or trajectory does not have any meaning for quantum objects, which exist in probabilistic quantum states.

Since you ask, QM can sort-of 'break' this law though, very temporarily, via the uncertainty principle. Many particle decays are mediated by 'virtual particles', which are heavier than the input particles. For example, a neutron can decay into an electron+neutrino+proton (Beta decay), this is mediated by a W boson which is ~80 times heavier than the neutron. So in a way energy is 'borrowed' to create the W, which then promptly decays into the lighter electron+neutrino, so in the end energy is conserved.