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Physicists Create World’s First Time Crystal

technologyreview.com

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Re: Physicists Create World’s First Time Crystal

#81

Post by gcr »

Dylan16807 wrote: post #28
oh_sigh wrote: post #21

Earlier quoted context omitted.

No - oscillators need constant energy input in order to operate. Time crystals require no energy for temporal repetition.

That's not really right. You can oscillate without constant energy input. Two particles can orbit forever. But normally that oscillation represents stored energy. They key to a time crystal is that it's oscillating while it's in a minimum energy state. It would take energy to make it stop moving.

A pendulum in a vacuum will oscillate forever, requiring energy to stop. Is it like that?

Re: Physicists Create World’s First Time Crystal

#82

Post by lisper »

zeroer wrote: post #80
lisper wrote: post #60

Earlier quoted context omitted.

Years of practice :-) Seriously though, I don't actually know much about QM, I only know the One Thing that makes the rest of QM easy to understand (kind of like knowing Lisp makes the rest of computer programming easy to understand). In case you want to know that One Thing, it's written up here: http://www.flownet.com/ron/QM.pdf There's also a movie version: https://www.youtube.com/watch?v=dEaecUuEqfc

I watched your video. Viewing measurement and entanglement as the same thing or closely related is ineresting, and the EPRG experiment is clever. I've never seen that before. Thanks for that! I need to think about it for a bit. But I think you give too short a shrift to Many-Worlds because it's not intuitive to you. Plenty of things about QM are not intuitive; I don't think that's sufficient reason to reject it.

I didn't reject it (at least I don't think I did -- it has been a while since I watched the video). I believe I said that both "many-worlds" and "zero-worlds" were equally legitimate -- only "one-world" (Copenhagen) is untenable.

[UPDATE] Yes, my recollection is correct. Go watch it again starting at the 58 minute mark or a little earlier.

Re: Physicists Create World’s First Time Crystal

#83

Post by zeroer »

lisper wrote: post #82
zeroer wrote: post #80

Earlier quoted context omitted.

I watched your video. Viewing measurement and entanglement as the same thing or closely related is ineresting, and the EPRG experiment is clever. I've never seen that before. Thanks for that! I need to think about it for a bit. But I think you give too short a shrift to Many-Worlds because it's not intuitive to you. Plenty of things about QM are not intuitive; I don't think that's sufficient reason to reject it.

I didn't reject it (at least I don't think I did -- it has been a while since I watched the video). I believe I said that both "many-worlds" and "zero-worlds" were equally legitimate -- only "one-world" (Copenhagen) is untenable. [UPDATE] Yes, my recollection is correct. Go watch it again starting at the 58 minute mark or a little earlier.

During the end questions yes, but at timestamp 43:20: "But I personally find [Many-Worlds] takes a heavier toll on my intuition than I'm willing to concede."

Re: Physicists Create World’s First Time Crystal

#84

Post by jasonwatkinspdx »

lisper wrote: post #77
jasonwatkinspdx wrote: post #69

Earlier quoted context omitted.

Just be aware that while Dr. Garret is very smart (and very accomplished with software) he is not a physicist. When this talk first came out I asked a couple people who do know QFT in detail about it and they were quite dismissive.

It's true. I'm not a physicist. I have never claimed to be a physicist. The only contribution I have ever claimed is a pedagogical one. When I first wrote the paper 15 years ago I submitted it to Physics Today. It was rejected, not because it was wrong, but because the reviewers thought that it was nothing new, that everyone already knew this stuff. Since then the physics community has bifurcated rather neatly into t…

I'm not qualified to adjudicate this, but I would point out that painting yourself as revealing a conspiracy doesn't do you any favors IMO.

Edit: downvote me all you like, but at least be accurate. I'm referring to the title of the tech talk video linked several times in this thread: "The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know"

Re: Physicists Create World’s First Time Crystal

#85

Post by JonnieCache »

klunger wrote: post #61

>But the laws of physics are not only symmetrical in space but also in time. Can someone explain what this means? It makes sense that physical laws are symmetrical in space. But in time? I thought that would not be the case because of entropy/irreversible processes etc. What am I missing? The whole article rests on this premise.

Here's a link to the videos from FXQi's Setting Time Aright conference, where there are lots of talks addressing the relationships between cosmology, QM and entropy with regards to time, with David Albert, Sean Carroll, Max Tegmark, Tim Maudlin, etc etc.

https://www.youtube.com/watch?v=QR9reQrumS0&list=PL1FA30AE29...

Spolier alert: they don't really know whats going on, and they disagree pretty strongly. Decoherence seems related to the thermodynamic arrow of time: you can't un-measure something, but famously we don't know how to interpret that, many worlds blah blah.

Re: Physicists Create World’s First Time Crystal

#86

Post by PetahNZ »

lisper wrote: post #79
ams6110 wrote: post #78

Earlier quoted context omitted.

Sounds almost like how words appear to be moving across a scrolling led (or previously, incandescent bulb) display, when nothing is moving it's just each led/bulb switching from lit to unlit.

That is (almost) exactly right. The only difference is that with classical states it is possible to distinguish between the object (the light bulb) and the state (on or off). With quantum systems the object is the state, so there is no way to distinguish between "the same atom" and "different atoms with the same state".

So if these are just states turning on and off, can we turn the state to on in multiple places at the same time?

Re: Physicists Create World’s First Time Crystal

#88

Post by Dylan16807 »

gcr wrote: post #81
Dylan16807 wrote: post #28

Earlier quoted context omitted.

That's not really right. You can oscillate without constant energy input. Two particles can orbit forever. But normally that oscillation represents stored energy. They key to a time crystal is that it's oscillating while it's in a minimum energy state. It would take energy to make it stop moving.

A pendulum in a vacuum will oscillate forever, requiring energy to stop. Is it like that?

It requires force to stop. But you can output energy as you do so. Not so with these. They have 'no' energy despite movement.

Re: Physicists Create World’s First Time Crystal

#89

Post by bjelkeman-again »

jasonwatkinspdx wrote: post #84
lisper wrote: post #77

Earlier quoted context omitted.

It's true. I'm not a physicist. I have never claimed to be a physicist. The only contribution I have ever claimed is a pedagogical one. When I first wrote the paper 15 years ago I submitted it to Physics Today. It was rejected, not because it was wrong, but because the reviewers thought that it was nothing new, that everyone already knew this stuff. Since then the physics community has bifurcated rather neatly into t…

I'm not qualified to adjudicate this, but I would point out that painting yourself as revealing a conspiracy doesn't do you any favors IMO. Edit: downvote me all you like, but at least be accurate. I'm referring to the title of the tech talk video linked several times in this thread: "The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know"

There was no conspiracy mentioned. Just people disagreeing about a hard subject.

Re: Physicists Create World’s First Time Crystal

#90

Post by andrewflnr »

jasonwatkinspdx wrote: post #84
lisper wrote: post #77

Earlier quoted context omitted.

It's true. I'm not a physicist. I have never claimed to be a physicist. The only contribution I have ever claimed is a pedagogical one. When I first wrote the paper 15 years ago I submitted it to Physics Today. It was rejected, not because it was wrong, but because the reviewers thought that it was nothing new, that everyone already knew this stuff. Since then the physics community has bifurcated rather neatly into t…

I'm not qualified to adjudicate this, but I would point out that painting yourself as revealing a conspiracy doesn't do you any favors IMO. Edit: downvote me all you like, but at least be accurate. I'm referring to the title of the tech talk video linked several times in this thread: "The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know"

There is no conspiracy described in GP, only human politics as usual.
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