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The quantum source of space-time

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Re: The quantum source of space-time

#101

Post by gsteinb88 »

lisper wrote: post #79
armitron wrote: post #70

Earlier quoted context omitted.

You do realize this is an open question right? No jokeprod paper or video is going to put it to rest. You sound like a religious nutcase.

I realize that a lot of people think it's an open question. These people are wrong. And the difference between me and a religious nutcase is that I can back up my position with math.

Important to remember, especially if you're practicing physics or engineering in any form: models are not the real world. You're (kind of) right about the (typical interpretation of) the models we use for entanglement, but open questions in this field include things like whether a wavefunction is "real" or just a mathematical tool that seems to get the right results at the length/energy scales we look at.

tl;dr: Just because you have an equation doesn't mean that equation corresponds to anything real. This is the same mistake people make all the time with statistics -- the math is easy, finding the right math to use can be very hard.

Re: The quantum source of space-time

#102

Post by typon »

lisper wrote: post #79
armitron wrote: post #70

Earlier quoted context omitted.

You do realize this is an open question right? No jokeprod paper or video is going to put it to rest. You sound like a religious nutcase.

I realize that a lot of people think it's an open question. These people are wrong. And the difference between me and a religious nutcase is that I can back up my position with math.

You sound a lot like Sean Carrol in this video:

https://www.youtube.com/watch?v=GdqC2bVLesQ

Being so sure about your position when it isn't proven is a pretty bad way to do science. You're essentially implying that 3/4 people on that stage are wrong or idiots. I don't buy it.

Re: The quantum source of space-time

#103

Post by lisper »

Xcelerate wrote: post #100
lisper wrote: post #36

Earlier quoted context omitted.

The issue is not so much with the word "determine" as it is with the word "instantaneously". You could say "Entanglement lets the measurement of one particle instantaneously frob the state of a partner particle" without knowing or specifying what the word "frob" means and you'd have the same problem: you're claiming that measuring one particle does something to the other particle, and does it instantaneously and, mor…

No one denies that when a measurement is performed, the measuring system and the measured system become entangled (and the aggregate system containing both continues evolving unitarily). > When you "measure" the two halves of an EPR pair what you are really doing is performing two measurements on whatever system produced the EPR pair to begin with. Here's the problem with that. Consider the measurements of a pair of…

>No one denies that when a measurement is performed, the measuring system and the measured system become entangled (and the aggregate system containing both continues evolving unitarily).

It's not true that no one denies this. Adherents of the Copenhagen interpretation deny it. They claim that measurement involves a non-unitary phenomenon called "wave function collapse."

> I can't quite tell exactly what you all are arguing about.

Exactly this. You may not realize it, but not everyone understands that measurement and entanglement are intimately related (in fact, the exact same physical phenomenon). In fact, some people vehemently deny it. There are even some card-carrying physicists who vehemently deny it.

> entanglement is not a phenomenon that can be explained classically.

That is certainly true (though I've met people who deny this as well).

Re: The quantum source of space-time

#104

Post by lisper »

typon wrote: post #102
lisper wrote: post #79

Earlier quoted context omitted.

I realize that a lot of people think it's an open question. These people are wrong. And the difference between me and a religious nutcase is that I can back up my position with math.

You sound a lot like Sean Carrol in this video: https://www.youtube.com/watch?v=GdqC2bVLesQ Being so sure about your position when it isn't proven is a pretty bad way to do science. You're essentially implying that 3/4 people on that stage are wrong or idiots. I don't buy it.

I'm on the road with extremely limited internet connectivity so I can't watch a video at the moment. But may I make a suggestion? Why don't you read my paper or watch my video before you decide that I'm wrong. In fifteen years, no one who has actually read it has taken issue with it. (And, BTW, the only reason it isn't a published peer-reviewed publication is that when I submitted it, it was rejected on the grounds that it wasn't anything new. Which is true. Which is why I stopped trying to publish it.)

Re: The quantum source of space-time

#105

Post by criddell »

gibybo wrote: post #23
reduxotron wrote: post #19

Earlier quoted context omitted.

We therefore reject the hypothesis that local realism governs our experiment. They reject a hypothesis . Nothing more. They did not prove that they changed an existing state. They merely decided that the state was not present, until measured. They decided a thing was not visible until looked at, because that makes more sense on paper .

Check out https://www.youtube.com/watch?v=ZuvK-od647c It's my favorite video for explaining how we know that the state is not determined until it has been measured. It's not just a decision we thought up on paper. It is real and well proven.

If you measure the spin, wait for a bit, then measure again, is the state known between the two measurements?

Re: The quantum source of space-time

#106

Post by Xcelerate »

lisper wrote: post #103
Xcelerate wrote: post #100

Earlier quoted context omitted.

No one denies that when a measurement is performed, the measuring system and the measured system become entangled (and the aggregate system containing both continues evolving unitarily). > When you "measure" the two halves of an EPR pair what you are really doing is performing two measurements on whatever system produced the EPR pair to begin with. Here's the problem with that. Consider the measurements of a pair of…

>No one denies that when a measurement is performed, the measuring system and the measured system become entangled (and the aggregate system containing both continues evolving unitarily). It's not true that no one denies this. Adherents of the Copenhagen interpretation deny it. They claim that measurement involves a non-unitary phenomenon called "wave function collapse." > I can't quite tell exactly what you all are…

My apologies, I was editing my post while you were replying to it.

> the aggregate system containing both continues evolving unitarily.

The Copenhagen interpretation is that the measured subsystem collapses in a non-unitary way. That doesn't imply the overall system did. I have no opinion* on whether a measured subsystem collapses unitarily or not — the answer to that question does not currently seem to be experimentally testable. But it is testable that the overall system continues evolving unitarily during a subsystem collapse (well, at least up until the overall system is measured), and this has been tested and verified many times.

(* Ok fine, I do have an opinion. I don't think unitarity breaks — ever. I think it appears to break through the process of decoherence. But I'm certainly not going to claim that as fact unless experiment can prove it somehow.)

Re: The quantum source of space-time

#107

Post by AnimalMuppet »

simonh wrote: post #61
hellofunk wrote: post #57

Earlier quoted context omitted.

Beautiful stuff, man. One of the more interesting questions I've seen asked in my casual hobby readings lately is: "Is the Universe quantized?" Meaning of course, is there a final limit to how small things get, and, with the passing of time, does it flow freely or pass in very tiny quantized periods?

I don't see how that would work with length contraction and time dilation. A unit quantum length object in my frame of reference would have different length to one in a frame at motion relative to mine, and time for it would pass at different quantum clock ticks. I don't see how a universe like that could work when it came to interactions between moving particles.

You're assuming that the Lorentz contraction applies unchanged as you move to the Planck length. That's not a given.

Re: The quantum source of space-time

#108

Post by lisper »

gsteinb88 wrote: post #101
lisper wrote: post #79

Earlier quoted context omitted.

I realize that a lot of people think it's an open question. These people are wrong. And the difference between me and a religious nutcase is that I can back up my position with math.

Important to remember, especially if you're practicing physics or engineering in any form: models are not the real world. You're (kind of) right about the (typical interpretation of) the models we use for entanglement, but open questions in this field include things like whether a wavefunction is "real" or just a mathematical tool that seems to get the right results at the length/energy scales we look at. tl;dr: Just…

No, these are not open questions. QIT answers all of them. It describes exactly how classical reality emerges from the quantum wave function, and hence settles the question of whether or not it is "real". The answer is: the question of whether or not the wave function is "real" is based on the false a assumption that "real" is a binary predicate. It isn't. Whatever the mathematics of the wave function describes does indeed exist, but it exists in a separate ontological category from classical reality.

See blog.rongarret.info/2015/02/31-flavors-of-ontology.html for more details.

Re: The quantum source of space-time

#109

Post by Retra »

criddell wrote: post #98
Retra wrote: post #97

Earlier quoted context omitted.

Mathematics is a human language for studying the structure of various experiences. To say the universe "is" mathematics without saying what mathematics is doesn't really say much at all. You might as well say it's magic. And, saying that it's a "mathematical structure" is just saying that it's a structure that humans can apply mathematics to model. So there's really no mechanism for this to be true, except in the tri…

> Mathematics is a human language for studying the structure of various experiences I think you are getting hung up on the semiotics of mathematics which is indeed a human construct. The idea of "1 + 1 = 2" is true no matter how (or if) you represent the idea. > saying that it's a "mathematical structure" is just saying that it's a structure that humans can apply mathematics to model That's not what the theory says (…

The math universe hypotheses assumes a very strict Platonist POV, which is not really a justifiable position, in my experience.

>The idea of "1 + 1 = 2" is true no matter how (or if) you represent the idea.

That's really a triviality, though. If you have the idea that 1+1=2, then yes, it's true. Usually people say mathematical theorems are true in "all possible universes", but the way they select which universes are possible is... by applying logic that works in this universe. 1+1=2 is only true because it doesn't contradict our experiences. It's useful. In another universe, it may not be useful, and thus wouldn't be true there.

>if you could simulate a universe and in that simulated universe you modeled people and all the stuff around them, what would you tell those simulated people with their simulated free well what a table is made out of?

I would put words in whatever order was most useful to them to employ for the construction and manipulation of tables. Anything else would be meaningless. You might as well just say "magic" if they can't use it.

Re: The quantum source of space-time

#110

Post by noobermin »

criddell wrote: post #105
gibybo wrote: post #23

Earlier quoted context omitted.

Check out https://www.youtube.com/watch?v=ZuvK-od647c It's my favorite video for explaining how we know that the state is not determined until it has been measured. It's not just a decision we thought up on paper. It is real and well proven.

If you measure the spin, wait for a bit, then measure again, is the state known between the two measurements?

Depends on the experiment.

If it is a "perfect experiment" (gedankenexperiment), and you measure the spin in the same direction a second time while not perturbing the experiment in anyway, the state should be in the state you measured it before. It is now an eigenstate of the spin operator (say, if you measured in a direction z, it is an eigenstate of S_z) and it will stay that way until it is disturbed.

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