Berkeley Lab proposes 4D clock It’s not quite a perpetual motion machine: scientists at the US Lawrence Berkeley National Laboratory have proposed a design for a timing crystal they say would theoretically outlast the universe. In this paper, published on Arxiv, the researchers propose a design for "a 4D crystal that has periodic structures in both space …
And in such a universe, it's almost certain that these entities have already arisen by chance. One may just have to look very hard to find them- I can imagine a cloud of these somewhere in interstellar or intergalactic space.
If they emit no energy, so as to not break the laws of thermodynamics*, how does one use them as a crystal? Currently crystals are used by energising them and allowing them to oscillate, but they do emit energy.
* The Laws Of Thermodynamics, to wit:
Law 1: You can't win, you can only break even.
Law 2: You can only break even at absolute zero.
Law 3: You can't reach absolute zero.
Law 0: You must play the game at all times.
Thank you Jonski for restating those Laws. I'd forgotten them even as I obey them.
As you age, you realize you are not perpetual, nor infinite. However a pint does remove the sting of realization.
"Malt does more than Milton can
To justify God's ways to man."
"a spatial ring of trapped ions in persistent rotation will periodically reproduce itself in time, forming a temporal analog of an ordinary spatial crystal. With a periodic structure in both space and time, the result is a space-time crystal."
Sorry I could not resist that. It is in fact a very interesting concept, it is just that the description had a certain "new age" ring to it.
I think that part of the conundrum is explained in this paragraph:
"However, there’s an escape clause at the quantum level: the ions can be given a push with a weak magnetic field, to get them rotating, and since they lose no energy to the outside world, that rotation should continue forever – even, according to research leader Xiang Zhang, after the “heat death” of the universe. And since there is no energy output from the crystal, it doesn’t break the rules to offer a perpetual motion machine."
However, what is not clear to me is how one is meant to "read" this clock. The action in so doing would surely impart energy to the system, a sort of "observer effect"? If by observing one imparts energy to the system is it not then above the zero state referred in the article? It is of course highly likely that I am missing something here because this is not my field. Is there a physicist in the house?
If there are enough ions in the ring, you can read the ion positions without exciting the ring into a higher state, using laser pulses. The more ions there are, the greater the perturbation it can tolerate. However, a nonzero temperature does cause the "clock" to slow down. It's all in the paper.
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And what about quantum effects (quantum fluctuations, virtual particles, tunneling particles, etc) that make a closed system impossible in our universe? Wouldn't they eventually cause the system to go into a higher state like the inflaton field did during the start of the big bang?
Reminds me of the early 20th solution of how to synchronise mechanical slave clocks from the finely tuned master. Instead of a mechanical pick-up they had a slot on the pendulum through which a light shone. This nominally frictionless method created an electrical sine wave on a detector.
The same reference book concludes with a chapter on "Quartz Crystal Clocks":
"But I see no prospect of a popular domestic clock in a quartz crystal. [...] This is of enormous value to science and I see no objection to leaving it alone to fulfil its lofty functions which seem to me to be its true destiny. It would be an impertinence for a clockmaker to covet it and attempt to harness it to his mundane purposes."
"Electrical Timekeeping" by Frank Hope Jones published 1949 - facsimile reprint 1976.
because these are ions in a ring they have a multipole moment, like dipole but higher order, lets say 12-pole for 12 atoms. This will radiate electromagnetic energy as the ring rotates, you could pick-up a signal much as the way a gear-tooth magnetic sensor does in your car. You can detect the rotation, hence energy is being lost, and it will slow down to a stop.
I'd also like to point out that there's nothing in the laws of physics that forbid perpetual motion. They just forbid perpetual motion machines. A machine does work. A spinning mass in isolation from anything else cannot do any work, therefore it could keep spinning forever. However it wouldn't be a machine because it couldn't do work. As soon as the system starts interacting with something else it could be put to work, but its energy would be dissipated in the process.
Spinning forever? Quite possible. Perpetual motion machines? Not so much.
The first is something I read somewhere, somewhen about using the Casimir force at ever-decreasing scale as a method of tapping into the zero point potential.
The second, which is probably quite closely related and maybe inspired by it, is Greg Egan's The Planck Dive [sic] where a group of astronauts facing a kind of entropy death aim to get around the problem by transferring themselves into self-replicating nano machines and firing themselves at a black hole's event horizon. The idea being that relative time slows down enough for them that they can construct a new shell slightly closer to the event horizon and transfer their conciousness into it further down into it so that even in an (absolute) finite time they still experience (relative) immorality.
Both stories wilfully ignore the fact that even though zero point energy might be infinite, the usable energy approaches zero. Planck scale and all that. No perperpetual motion today, then (or yesterday, or whenever).
But what does it all mean, Jimmy? Fucked if I know, Terry.
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