Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Physicists Create World’s First Time Crystal

technologyreview.com

Post reply on HN
Print view View original

91–100 of 130 posts

Re: Physicists Create World’s First Time Crystal

#91

Post by questionr »

lisper wrote: post #60
davesque wrote: post #51

Earlier quoted context omitted.

Thanks for the great explanation. Serious question: Can I ask how you happen to know so much about this subject?

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

didn't do the math, but sounds plausible though I know barely anything of quantum mechanics.

just to confirm my interpretation, its saying that:

- fundamentally the universe is governed by quantum mechanics

- classical physics doesn't truly exist

- the classical physics we see and intuit can be explained by entropy (information theory) of the quantum state

- measurement and entanglement are the same in the sense that both imparts "information" into the system. this in effect acts as a "filter", an example of which is the double-slit experiment where the waves are "filtered" to particles when being measured

- our conscious mind is a classical construct so its naturally difficult to intuit quantum laws

is that mostly correct? also, how popular is this theory in the physics community?

Re: Physicists Create World’s First Time Crystal

#92

Post by lisper »

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"

You obviously didn't watch even the first minute of the talk because the very first thing I say is that the title is tongue-in-cheek and there is no conspiracy.

Re: Physicists Create World’s First Time Crystal

#93

Post by lisper »

zeroer wrote: post #83
lisper wrote: post #82

Earlier quoted context omitted.

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."

OK, well, I think it's a little unfair to characterize that as a "rejection." But my thinking has evolved a bit in the past five years. The difference between zero-worlds and many-worlds is the difference between taking a personal point of view or a God's-eye-view. God can see the many-worlds, but I can't, so it makes more sense to me to assign a privileged status to this world, the one I live in. But then I have to make my peace with the fact that this world is not as it appears to be, and I do that by thinking of it as a (very high quality) simulation. But that just my personal approach. Reasonable people can (and do) disagree.

Re: Physicists Create World’s First Time Crystal

#94

Post by lisper »

questionr wrote: post #91
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

didn't do the math, but sounds plausible though I know barely anything of quantum mechanics. just to confirm my interpretation, its saying that: - fundamentally the universe is governed by quantum mechanics - classical physics doesn't truly exist - the classical physics we see and intuit can be explained by entropy (information theory) of the quantum state - measurement and entanglement are the same in the sense that…

> is that mostly correct?

Mostly.

> also, how popular is this theory in the physics community?

Not very. The fashionable way to think about this stuff is something called "decoherence" which really amounts to the same thing but phrased in different terms.

Re: Physicists Create World’s First Time Crystal

#95

Post by questionr »

lisper wrote: post #94
questionr wrote: post #91

Earlier quoted context omitted.

didn't do the math, but sounds plausible though I know barely anything of quantum mechanics. just to confirm my interpretation, its saying that: - fundamentally the universe is governed by quantum mechanics - classical physics doesn't truly exist - the classical physics we see and intuit can be explained by entropy (information theory) of the quantum state - measurement and entanglement are the same in the sense that…

> is that mostly correct? Mostly. > also, how popular is this theory in the physics community? Not very. The fashionable way to think about this stuff is something called "decoherence" which really amounts to the same thing but phrased in different terms.

Thanks!

so if i were to do further research into this, I would use the keyword "decoherence"?

also not being a physicist, could I naively think this would be a good candidate for the "theory of everything"?

Re: Physicists Create World’s First Time Crystal

#96

Post by nickpsecurity »

lisper wrote: post #58
Jcol1 wrote: post #49

Earlier quoted context omitted.

Isn't the entire universe one quantum system? If so, how can we talk about discrete systems. Also, when you say there are not discrete things, do you mean in the QFT sense of field excitations?

> Isn't the entire universe one quantum system? Yes. > If so, how can we talk about discrete systems. That is an excellent question! And the answer is that when you do the math, the result of taking a subset of the wave function (the mathematical operation is called a "trace") is something that looks like a classical system. If you want the details, see this paper: http://www.flownet.com/ron/QM.pdf Or this video http…

" And the answer is that when you do the math, the result of taking a subset of the wave function (the mathematical operation is called a "trace") is something that looks like a classical system."

Your statement just connected to unrelated subjects in my head that might mean something. As I studied hardware, I found that underneath these nice, mathematical blocks that we build digital with are analog components that appear to operate on messy, kind-of-chaotic waves of electricity they hand-tune into the digital cells. Then, you say the clean building blocks of classical systems are composed of messy waves in quantum. Worded like that, it makes me wonder if analog vs digital could teach us something about quantum vs classical. Or some universal principle at work. Reason I wonder is some of the math keeps showing up in different disciplines.

What you think? Is my brain overreaching on this?

Re: Physicists Create World’s First Time Crystal

#97

Post by jasonwatkinspdx »

lisper wrote: post #92
jasonwatkinspdx wrote: post #84

Earlier quoted context omitted.

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"

You obviously didn't watch even the first minute of the talk because the very first thing I say is that the title is tongue-in-cheek and there is no conspiracy.

I did, though it's been several years. Making an inflammatory statement, then denying it as a joke is a common mild double bind, one that's best avoided. I'm not speaking toward your intentions as I obviously don't know them. I'm just pointing out that particular rhetorical form isn't doing you any favors, again, IMO.

Re: Physicists Create World’s First Time Crystal

#98

Post by zer0gravity »

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 by saying this, you're actually saying that we're living in some sort of state machine / cellular automata universe, and in order to understand it, we just have to find the rules of interaction/propagation of the states ?

Re: Physicists Create World’s First Time Crystal

#99

Post by lisper »

questionr wrote: post #95
lisper wrote: post #94

Earlier quoted context omitted.

> is that mostly correct? Mostly. > also, how popular is this theory in the physics community? Not very. The fashionable way to think about this stuff is something called "decoherence" which really amounts to the same thing but phrased in different terms.

Thanks! so if i were to do further research into this, I would use the keyword "decoherence"? also not being a physicist, could I naively think this would be a good candidate for the "theory of everything"?

> so if i were to do further research into this, I would use the keyword "decoherence"?

Decoherence, relational quantum mechanics, quantum information theory, the Von Neuman measurement model -- all of these turn out to be the same thing.

> also not being a physicist, could I naively think this would be a good candidate for the "theory of everything"?

No, the "theory of everything" refers to the unification of quantum mechanics and relativity. Completely different topic.

Re: Physicists Create World’s First Time Crystal

#100

Post by lisper »

nickpsecurity wrote: post #96
lisper wrote: post #58

Earlier quoted context omitted.

> Isn't the entire universe one quantum system? Yes. > If so, how can we talk about discrete systems. That is an excellent question! And the answer is that when you do the math, the result of taking a subset of the wave function (the mathematical operation is called a "trace") is something that looks like a classical system. If you want the details, see this paper: http://www.flownet.com/ron/QM.pdf Or this video http…

" And the answer is that when you do the math, the result of taking a subset of the wave function (the mathematical operation is called a "trace") is something that looks like a classical system." Your statement just connected to unrelated subjects in my head that might mean something. As I studied hardware, I found that underneath these nice, mathematical blocks that we build digital with are analog components that…

The difference between classical and quantum is not really analogous to the difference between digital and analog, it's the difference between real numbers and Turing machines (classical) and complex numbers (quantum).

But the ability of classical math to model all this is truly extraordinary.

https://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.htm...

Post reply on HN