The Ur-Quan Masters Discussion Forum

The Ur-Quan Masters Re-Release => Starbase Café => Topic started by: Zanthius on July 30, 2018, 09:18:21 am



Title: Temporal information assymtery
Post by: Zanthius on July 30, 2018, 09:18:21 am
Since we have much more information about the past than about the future, our brains might have developed a bias which makes us assume a causal connection from the past to the future.  If we collected billions of data points between the first and second world war and fed the data points to a machine learning algorithm, would the machine learning algorithm believe that the data points from the first world war necessarily gave rise to the data points from the second world war, or could it perhaps also come to the conclusion that the data points from the second world war retro-caused (https://en.wikipedia.org/wiki/Retrocausality) the first world war?

I suspect that it might be an equally valid interpretation that the data points from the second world war retro-caused the first world war.  You might argue that according to the many-worlds interpretation (https://en.wikipedia.org/wiki/Many-worlds_interpretation) of quantum physics, there isn't necessarily just one possible future, but rather an almost infinite number of possible futures. However, according to the multiple histories interpretation (https://en.wikipedia.org/wiki/Multiple_histories) of quantum physics, there isn't necessarily just one past either.

Maybe our belief about the past causing the future is just a bias formed because our brains have much more information about the past than about the future.


Title: Re: Temporal information assymtery
Post by: Death 999 on July 30, 2018, 01:57:37 pm
That is not how MWI works. QM obeys forwards causality, and not retrocausality.

What they're seeing must have an 'also a consequence' relationship to the causes of more notable events. Or QM is actually wrong and the universe is even weirder. I'd put my money on the former.


Title: Re: Temporal information assymtery
Post by: Zanthius on July 30, 2018, 02:20:26 pm
That is not how MWI works. QM obeys forwards causality, and not retrocausality.

What they're seeing must have an 'also a consequence' relationship to the causes of more notable events. Or QM is actually wrong and the universe is even weirder. I'd put my money on the former.

Maybe you are right. I just find it somewhat suspicious to assume forward causality since we have much more information about the past than about the future. If I had as much information about the future as I now have about the past, and as little information about the past as I now have about the future, I am convinced that I would assume the universe to follow retrocausality.

But I don't have as much information about the future as about the past, and maybe there is a reason for that. Maybe there is no retrocausality.


Title: Re: Temporal information assymtery
Post by: Zanthius on July 30, 2018, 09:15:16 pm
That is not how MWI works. QM obeys forwards causality, and not retrocausality.

This article seems to disagree:

Quote
The fundamental laws of physics work in the same way whether time moves forward or backward. Yet, while a glass can fall and scatter shards across the floor, glass shards never gather together and leap back onto the counter to form a complete glass. The source of this temporal asymmetry is one of the deepest mysteries in physics. We tackle this problem by combining two different disciplines, computational and quantum mechanics. Our results illustrate that the asymmetry could emerge from forcing classical causal explanations on observations in a fundamentally quantum world.

Computational mechanics asks the following question: Given a sequence of observations, how many past causes must we postulate to explain future behavior? This quantity is asymmetric when time is reversed. There is an unavoidable memory overhead cost for modeling a process in the “less-natural” temporal direction—one must pay a price to enforce explanations adhering to a less-favored order of events.

We show that quantum models always mitigate this overhead. Not only can we construct quantum models that need less past information than optimal classical counterparts, these models can always be reprogrammed to model the time-reversed process without additional memory cost. This remains true even for observational data where this classical overhead diverges, such that all classical models for the less-natural temporal direction require unbounded memory.

We illustrate scenarios where classical favoritism for particular causal orders vanishes when quantum models are permitted, thus highlighting a new mechanism for the origin of time’s arrow.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.8.031013 (https://journals.aps.org/prx/abstract/10.1103/PhysRevX.8.031013)


Title: Re: Temporal information assymtery
Post by: Death 999 on July 30, 2018, 11:34:37 pm
They're talking about where the arrow of time comes from. They don't deny that there is one. And that's all I need for QM to obey causality and not retrocausality. Newton's mechanics are time-reversible too, but we don't say it has retrocausality.

Do you know about the idea of boundary conditions setting the solutions of differential equations? Particularly, partial differential equations?

The universe seems to have a simple boundary condition 13.5 billion years in the past. Things that are further from this boundary condition a timelike direction are later. The symmetry of the rules of QM say that on the other side of this boundary condition - if there is one - forwards in time would be pointed the other direction, what we'd call into the past. But on our side of that event, forwards in time is forwards.

Greater proximity to this simple boundary condition is what we mean by 'earlier', and being further from it is what we mean by 'later'. This continues to apply in QM theories without parameter time ('timeless physics'), which you may have heard of. Most importantly, events closer to this boundary condition are logically prior to things further from it, and not vice versa.


Title: Re: Temporal information assymtery
Post by: Zanthius on July 31, 2018, 08:58:43 am
Greater proximity to this simple boundary condition is what we mean by 'earlier', and being further from it is what we mean by 'later'.


Interesting. So you believe that we have memories from the past since the particles in our region of the universe move away from a boundary condition? I assume this would be somewhat similar to a particle moving away from a black hole, or a particle decelerating from light speed.

Then, if particles moved towards a boundary condition, you think brains formed by such particles would have memories from the future? I assume this would be somewhat similar to a particle falling into a black hole, or a particle accelerating towards light speed.

Also. Do you think it could be possible for particles to move both away from a boundary condition and towards a different boundary condition at the same time? In that case, could perhaps the particles have memories both from the past and the future? Like this:

(https://i.imgur.com/pikT1lP.png)


Title: Re: Temporal information assymtery
Post by: Death 999 on July 31, 2018, 01:18:35 pm
Quote
So you believe that we have memories from the past since the particles in our region of the universe move away from a boundary condition? I assume this would be somewhat similar to a particle moving away from a black hole, or a particle decelerating from light speed.

Not exactly. It's more like if you have a guitar string, and you pluck on it, and release it. You have the boundary conditions at the ends of the string, they persist in time (because it's finite), and you have what is called the initial condition - what the state is when you release the string. But that's just a boundary condition along the past end of the string's history.

When you're calculating out the string's history future, for each section of the string, you look at the past neighborhood - the position and velocity of itself and the neighboring parts of the string. You look at that side because it's closer to the initial condition. Looking at the future neighborhood doesn't help because there isn't a constraint there. The future uses you; you do not use the future.

If you are doing it backwards in time, then it's nominally the future end, but really effectively it's the past end because it's what was fixed. You knew about that part before you knew about the things further backwards, if you're solving the equation numerically. And the second law of thermodynamics is acting in that direction, with more order towards that fixed point and less further away. It brings the vibrations up to a plucked string just in time for you to release it, if you run it 'forwards', but if you run it backwards, it looks normal.

So in no event do you get memories - or any consequences - from the future.

Unless, that is, there happens to be a boundary condition at both ends. But you'd immediately know about that because of massive violations of the second law of thermodynamics. Specifically, it wouldn't be like your having memories from the future. On your graph, we'd be around t = 5 or t = 95, and everything between 30 and 70 is what we'd think of as 'heat death of the universe' kinds of conditions. Another way of looking at it is that there are two universes there, and they have the same endpoint, but under time-reversal symmetry.


Title: Re: Temporal information assymtery
Post by: Zanthius on July 31, 2018, 01:34:01 pm
So in no event do you get memories - or any consequences - from the future.

Hmm... to me it seems like the big bang boundary condition gives "energy" to keep the particles alive, and that is why we get memories from the past, which is closer to the big bang boundary condition. But this energy declines over time, and that is why radioactive elements have a half-life. Maybe all particles have a half-life, but the half-life of a proton is so long that we haven't really observed any proton decaying.  However, if a proton starts to get "energy" from a future boundary condition before that, it might never decay, but rather become increasingly retrocausal.


Title: Re: Temporal information assymtery
Post by: Death 999 on July 31, 2018, 01:36:46 pm
A) I've modified my post; I suggest rereading the second and last paragraphs

B) the 'energy' you've put in quotes is a lot like thermodynamic free energy, but I wouldn't want to guarantee that it's exactly the same.

C) in the retrocausal regime, you'd see an exponential un-decaying as decay products seemingly randomly flew in and combined. It would be exactly like normal events going backwards.

The only time when physics would make sense in both directions is when everything is at maximum entropy already - heat death of the universe conditions. When you have as much organization as a person, only one direction makes sense.


Title: Re: Temporal information assymtery
Post by: Zanthius on July 31, 2018, 03:45:01 pm
C) in the retrocausal regime, you'd see an exponential un-decaying as decay products seemingly randomly flew in and combined. It would be exactly like normal events going backwards.

I don't think it would look like that at a macroscopical scale. Only at a microscopical scale. It wouldn't necessarily make all the variety of macroscopical structures we have today, but rather just assimilate particles into a super highly organized microscopical structure, which expands until it has incorporated all the particles at the boundary condition.

I wonder if this super highly organized microscopical structure could have some kind of consciousness. If so, it might remember only its future, and nothing from its past.... far into the future would be vague memories, while its near future would be more clear memories. This super highly organized microscopical structure sounds a bit like Juffo-Wup:

Quote
Juffo-Wup is All... omni-existent, spreading and changing the Non into Juffo-Wup.
It flows through all things, binding them together, making them one.

When Juffo-Wup is complete
when at last there is no Void or Non
when the boundary condition returns
then we can finally rest.



Title: Re: Temporal information assymtery
Post by: Death 999 on July 31, 2018, 06:20:31 pm
Quote
I don't think it would look like that at a macroscopical scale. Only at a microscopical scale

I'd ask why you would think so, except that the rest of the paragraph is word salad. You have left the realm of physics and entered word games that aren't even philosophy.



Title: Re: Temporal information assymtery
Post by: Zanthius on July 31, 2018, 07:02:22 pm
I'd ask why you would think so

If you made a simulation where you made the conditions so that the second law of thermodynamics was reversed, I think you would see that things started to organize themselves at a microscopical scale, and it wouldn't necessarily look much like a video of the universe in reverse.

except that the rest of the paragraph is word salad. You have left the realm of physics and entered word games that aren't even philosophy.

I thought this was a Star Control 2 forum, not a physics forum....

I also think Jordan Peterson is right in that we need some kind of deeply rooted narrative. But when Jordan Peterson quotes from the Bible, I probably feel a bit like you do now, since I haven't been raised a Christian. However, his quotes from the Bible appeal to large segments of his fan base, since they have been raised as Christians and identify with the Christian narrative. To me, however, it seems like word salad.

Anyhow, there is plenty of research showing that humans learn better from stories:

Quote
Use of cognitive capacity was measured during reading of text in six experiments. Content features of the texts were varied. A secondary task technique was used to measure use of capacity. In all experiments, capacity was filled more completely while reading narrative text than while reading expository text. The finding was generalized over two pools of passages, over two modalities of secondary task probes— auditory and tactile—and over two secondary tasks—simple reaction time and choice reaction time. Three hypotheses for the narrativity effect were investigated. Not supported were an hypothesis based on the interest value of the passages and the hypothesis that difficult to comprehend passages induced problem solving cognitive operations that filled capacity. The results were consistent with a comprehensibility hypothesis, which states that when more meaning is produced in the reader's cognitive system while reading a text, more cognitive capacity is filled by reading it. Narrative passages produce more meaning because schemata for narrative texts are more familiar, more frequently encountered, and easier to comprehend than schemata for expository texts.

https://www.tandfonline.com/doi/abs/10.1080/01638538309544553 (https://www.tandfonline.com/doi/abs/10.1080/01638538309544553)

And, as far as stories go, I don't think stories from Star Control 2 is a particularly bad choice, although I also like some of the stories by Greg Egan (https://en.wikipedia.org/wiki/Greg_Egan).


Title: Hyperorganization
Post by: Zanthius on August 01, 2018, 11:02:51 pm
I bought a new domain in regards to this:

https://www.hyperorganization.org/ (https://www.hyperorganization.org/)


Title: Re: Temporal information assymtery
Post by: Zanthius on August 14, 2018, 01:10:18 am
Maybe the universe is inside of a machine going like this:

(https://www.hyperorganization.org/test.gif)

Also, if the universe is expanding, aren't we getting longer and longer away from the heat death, since there are more possible configurations in a larger universe? Is entropy a measure of our distance from the big bang, or a measure of our distance from the heat death? It is not necessarily obvious that not both of these distances could increase if we count the number of steps.

(http://www.informationphilosopher.com/introduction/information/Growth_of_Info.png)


Title: Re: Temporal information assymtery
Post by: Zanthius on August 20, 2018, 10:40:08 am
Found this comment which claims that antimatter is going back in timet:

Quote
Antimatter is in every precise meaningful sense matter moving backward in time. The notion of "moving backward in time" is nonsensical in a Hamiltonian formulation, because the whole description can only go forward in time. That's the definition of what the Hamiltonian does--- it takes you forward in time a little bit. So if you formulate quantum mechanics the Hamiltonian way, this idea is difficult to understand (still it can be done--- Stueckelberg discovered this connection before the path integral, when field Hamiltonians were the only tool).

But in Feynman's particle path-integral picture, when you parametrize particles by their worldline proper time, and you renounce a global causal picture in favor of particles splitting and joining, the particle trajectories are consistent with relativity, but only if the trajectories include back-in-time trajectories, where coordinate time ticks in the opposite sense to proper time.

Looked at in the Hamiltonian formalism, the coordinate time is the only notion of time. So those paths where the proper time ticks in the reverse direction look like a different type of particle, and these are the antiparticles.

Sometimes there is an idenification, so that a particle is its own antiparticle.

Precise consequence: CPT theorem

The "C" operator changes all particles to antiparticles, the P operator reflects all spatial directions, and the T operator reflects all motions (and does so by doing complex conjugation). It is important to understand that T is an operator on physical states, it does not abstractly flip time, it concretely flips all momenta and angular momenta (a spinning disk is spinning the other way), so that things are going backwards. The parity operator flips all directions, but not angular momenta.

The CPT theorem says that any process involving matter happens exactly the same when done in reverse motion, in a mirror, to antimatter.

The CPT operator is never the identity, aside from the case of a real scalar field. CPT acting on an electron produces a positron state, for example. CPT acting on a photon produces a photon going in the same direction with opposite polarization (if P is chosen to reflect all spatial coordinate axes, this is a bad convention outside of 3+1 dimensions).

This theorem is proved by noting that a CPT operator corresponds to a rotation by 180 degrees in the Euclidean theory, as described on Wikipedia.

Precise consequence: crossing

Any amplitude involving particles A(k_1,k_2,...,k_n) is analytic in the incoming and outgoing momenta, aside from pole and cut singularities caused by producing intermediate states. In tree-level perturbation theory, these amplitudes are analytic except when creating physical particles, where you find poles. So the scattering amplitudes make sense for any complex value of the momenta, since going around poles is not a problem.

In terms of mandelstam variables for 2-2 scattering, s,t,u (s is the CM energy, t is the momentum transfer and u the other momentum transfer, to the other created particle), the amplitude is an analytic function of s and t. The regions where the particles are on the mass shell are given by mandelstam plot, and there are three different regions, corresponding to A+B goes to C+D , Cbar + B goes to Abar+ D, and A + Dbar goes to C+Bbar. These three regimes are described by the exact same function of s,t,u, in three disconnected regions.

In starker terms, if you start with pure particle scattering, and analyticaly continue the amplitudes with particles with incoming momentum k's (with positive energy) to negative k's, you find the amplitude for the antiparticle process. The antiparticle amplitude is uniquely determined by the analytic contination of the particle amplitude for the energy-momentum reversed.

This corresponds to taking the outgoing particle with positive energy and momentum, and flipping the energy and momentum to negative values, so that it goes out the other way with negative energy. If you identify the lines in Feynman diagrams with particle trajectories, this region of the amplitude gives the contribution of paths that go back in time.

So crossing is the other precise statement of "Antimatter is matter going back in time".

Causal pictures

The notion of going back in time is acausal, meaning it is excluded automatically in a Hamiltonian formulation. For this reason, it took a long time for this approach to be appreciated and accepted. Stueckelberg proposed this interpretation of antiparticles in the late 1930s, but Feynman's presentation made it stick.

In Feynman diagrams, the future is not determined from the past by stepping forward timestep by timestep, it is determined by tracing particle paths proper-time by proper-time. The diagram formalism therefore is philosophically very different from the Hamiltonian field theory formalism, so much so Feynman was somewhat disappointed that they were equivalent.

They are not as easily equivalent when you go to string theory, because string theory is an S-matrix theory formulated entirely in Feynman language, not in Hamiltonian language. The Hamiltonian formulation of strings requires a special slicing of space time, and even then, it is less clear and elegant than the Feynman formulation, which is just as acausal and strange. The strings backtrack in time just like particles do, since they reproduce point particles at infinite tension.

If you philosophically dislike acausal formalisms, you can say (in field theory) that the Hamiltonian formalism is fundamental, and that you believe in crossing and CPT, and then you don't have to talk about going back in time. Since crossing and CPT are the precise manifestations of the statement that antimatter is matter going back in time, you really aren't saying anything different, except philosophically. But the philosophy motivates crossing and CPT.

https://physics.stackexchange.com/q/17781 (https://physics.stackexchange.com/q/17781)

And these two videos about Feynman diagrams by PBS spacetime on youtube:

https://www.youtube.com/watch?v=fG52mXN-uWI (https://www.youtube.com/watch?v=fG52mXN-uWI)

https://www.youtube.com/watch?v=vSFRN-ymfgE (https://www.youtube.com/watch?v=vSFRN-ymfgE)

If it is the case that antimatter is going back in time, couldn't it be that more and more matter changes into antimatter as the universe progresses forwards in time, while more and more antimatter changes into matter as the universe progresses backwards in time.


Title: Re: Temporal information assymtery
Post by: Death 999 on August 20, 2018, 02:18:35 pm
Calling antimatter 'regular particles going back in time' is cute but only really helpful if you've got a Feynman diagram and you want to spin it around to face a different direction. It doesn't change the arrow of time problem. It is merely the absence of an arrow of time at the individual-interaction level, just like we had in Newtonian mechanics.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 20, 2018, 05:54:09 pm
Calling antimatter 'regular particles going back in time' is cute but only really helpful if you've got a Feynman diagram and you want to spin it around to face a different direction.

As far as I understand it, Feynman's path integral formulation is the best description we have of reality. As far as I understand it, earlier interpretations of quantum mechanics weren't compatible with special relativity.

Also, to get Feynman's path integral, you need to take into account virtual electrons going into the future and virtual positrons going into the past. And this is the most accurate description we have of reality. Without taking into account virtual positrons going into the past you get a much less accurate prediction. In fact, a many orders of magnitude less accurate prediction.


Title: Re: Temporal information assymtery
Post by: Death 999 on August 20, 2018, 08:36:52 pm
> Also, to get Feynman's path integral, you need to take into account virtual electrons going into the future and virtual positrons going into the past.

No.
You need either there to be a disturbance in the electron field where
if it's in one configuration it's called an electron and it goes forward in time and it looks like what we think of as an electron, or it can be in another configuration, and it looks like what we think of as a positron, but it's actually an electron going into the past,
OR,
if it's in one configuration it's called an electron and it goes forward in time and it looks like what we think of as an electron, or it can be in another configuration, and it looks like what we think of as a positron, because this other configuration is different like that and this is going into the future like everything else including the flow of information.

There is a vey strong symmetry which at the interaction level is vitally important. Focusing overly-closely on this level when trying to find the arrow of time will trip you up, because at that level there isn't one. Configurations don't travel through time. They are different at each time.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 20, 2018, 10:40:37 pm
Well, about the g-factor:

(https://i.imgur.com/5na7y1e.png)

According to Dirac, it should be 2:

(https://i.imgur.com/e4YOsSu.png)

However, it is measured to be around 2.00231930436146. The noise of 0.00231930436146 is from virtual interactions. When we use Feynman's path integral, and take all possible virtual interaction into account on modern supercomputers, we get a g-factor of: 2.0023193043552

(https://i.imgur.com/iRS4PlM.png)

https://www.youtube.com/watch?v=7UwigY4SjKY&t=123s (https://www.youtube.com/watch?v=7UwigY4SjKY&t=123s)

If you only took into account all possible interactions going into the future, I guess you would be able to explain half of the noise. Wouldn't that be many orders of magnitude less accurate?

(https://i.imgur.com/MmAoXI5.png)


Title: Re: Temporal information assymtery
Post by: Death 999 on August 21, 2018, 01:07:43 pm
Zanthius, which of us has actually taken a graduate school class in quantum field theory? You keep pulling out pop-sci explanation videos. I've derived the time-propagator and proven causality for quantum fields.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 21, 2018, 01:37:16 pm
Zanthius, which of us has actually taken a graduate school class in quantum field theory? You keep pulling out pop-sci explanation videos. I've derived the time-propagator and proven causality for quantum fields.

This seems like an argument from authority: https://en.wikipedia.org/wiki/Argument_from_authority (https://en.wikipedia.org/wiki/Argument_from_authority). If you have developed such a proof, why don't you post it here instead of making an appeal to authority?

I also doubt that you are more educated in quantum field theory than the guy speaking in the PBS spacetime videos.

Quote
Matt O'Dowd is an Australian-born astrophysicist. He is an assistant professor at the Physics and Astronomy Department at the Lehman College of the City University of New York[1] and writer and host of PBS Space Time on YouTube.[2] He is a frequent guest on Science Goes to the Movies on CUNY TV, and StarTalk radio with Neil deGrasse Tyson.[3]

https://en.wikipedia.org/wiki/Matt_O%27Dowd_(astrophysicist) (https://en.wikipedia.org/wiki/Matt_O%27Dowd_(astrophysicist))

Are you a professor in astrophysics?

Anyhow, if you proved time propagation in quantum fields, I guess you must have used a Hamiltonian formulation, which as far as I understand it is a more limited form of the Lagrangian formulation.

Quote
The Hamiltonian in classical mechanics is derived from a Lagrangian, which is a more fundamental quantity relative to special relativity. The Hamiltonian indicates how to march forward in time, but the time is different in different reference frames. The Lagrangian is a Lorentz scalar, while the Hamiltonian is the time component of a four-vector. So the Hamiltonian is different in different frames, and this type of symmetry is not apparent in the original formulation of quantum mechanics.

https://en.wikipedia.org/wiki/Path_integral_formulation#Quantum_action_principle (https://en.wikipedia.org/wiki/Path_integral_formulation#Quantum_action_principle)

I also doubt that your "proof" of time propagation is compatible with special relativity.

Quote
If the Lagrangian is invariant under a symmetry, then the resulting equations of motion are also invariant under that symmetry. This characteristic is very helpful in showing that theories are consistent with either special relativity or general relativity.

https://en.wikipedia.org/wiki/Lagrangian_mechanics#Noether's_theorem (https://en.wikipedia.org/wiki/Lagrangian_mechanics#Noether's_theorem)

Quote
Antimatter is in every precise meaningful sense matter moving backward in time. The notion of "moving backward in time" is nonsensical in a Hamiltonian formulation, because the whole description can only go forward in time. That's the definition of what the Hamiltonian does--- it takes you forward in time a little bit. So if you formulate quantum mechanics the Hamiltonian way, this idea is difficult to understand (still it can be done--- Stueckelberg discovered this connection before the path integral, when field Hamiltonians were the only tool).

https://physics.stackexchange.com/q/17781 (https://physics.stackexchange.com/q/17781)


Title: Re: Temporal information assymtery
Post by: Death 999 on August 21, 2018, 09:36:51 pm
I am saying that you are having interpretation problems because someone has dumbed it down to the point that you can do it without doing math you cannot reasonably be expected to do. And that math says that the two pictures, one with actual backwards time travel and one without, are equivalent. You can describe it that way for discussions of individual interactions because it's convenient - I'm not saying those people are wrong - , but when you get to discussions of macro-scale phenomena like thermodynamics, talking of actual propagation backwards in time is a mistake.

Note, at 7:25 in that video, he said 'one way to think about…' this. It's a view that has certain benefits for certain purposes. When you try to apply this view to other purposes without his saying it's a good idea, you lose all of the protection his authority grants.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 21, 2018, 10:05:04 pm
You can describe it that way for discussions of individual interactions because it's convenient - I'm not saying those people are wrong - , but when you get to discussions of macro-scale phenomena like thermodynamics, talking of actual propagation backwards in time is a mistake.

Of course. I am talking about virtual interactions. I don't think there are lots of non-virtual positrons here on Earth, and I guess that in order for something to go back in time at a macro-scale it might need to be built from large amounts of non-virtual antimatter which we don't necessarily have access to here on Earth.

However, if there are VIRTUAL positrons going back in time, it might prove that particles CAN go back in time, and certain aliens might have access to much more antimatter than us.

Maybe we also could use some weakly interacting antimatter to send a message back in time. Or if we built a magnetic field in a vacuum, maybe we could keep charged antimatter particles there, which could be used to send messages back in time within the magnetic field. The messages could be encoded as perturbations in the magnetic field generated by the antimatter ions.


Title: Re: Temporal information assymtery
Post by: Death 999 on August 21, 2018, 10:21:30 pm
Virtual-ness isn't a property of a particle. It's a property of a diagram you make about particles. If you have an electron undergo one interaction in one set of diagrams and then have it undergo another interaction in another set of diagrams, it's 'real' between them. But you are free to re-draw that as one big set of diagrams… and then suddenly the electron is 'virtual' all that time.

And diagrams are not fundamental. They are how you organize your knowledge about what the propagation operator is doing. The propagation operator itself points straight back to time being pointed away from simple boundary conditions.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 21, 2018, 10:31:29 pm
The propagation operator itself points straight back to time being pointed away from simple boundary conditions.

If you made a magnetic field in a vacuum, couldn't that function as a boundary condition? And if you keep antimatter inside the magnetic field, maybe ions inside the magnetic field will propagate in the opposite time-direction?

Also, isn't it possible that dark matter is made of weakly interacting antimatter?

Quote
New particle links dark matter with missing antimatter

Physicists in the US and Canada have proposed a new particle that could solve two important mysteries of modern physics: what is dark matter and why is there much more matter than antimatter in the universe?

The yet-to-be-discovered “X” particle is expected to decay mostly to normal matter, whereas its antiparticle is expected decay mostly to “hidden” antimatter. The team claims that its existence in the early universe could explain why there is more matter than antimatter in the universe – and that dark matter is in fact hidden antimatter.

https://physicsworld.com/a/new-particle-links-dark-matter-with-missing-antimatter/ (https://physicsworld.com/a/new-particle-links-dark-matter-with-missing-antimatter/)


Title: Re: Temporal information assymtery
Post by: Zanthius on August 22, 2018, 12:28:44 pm
And that math says that the two pictures, one with actual backwards time travel and one without, are equivalent.

Sure. I am not arguing that they aren't equivalent. But don't you get twice as many possibilities if you include both the forward possibilities and the backward possibilities? Why do you think the g-factor is around 2 and not around 1?

And diagrams are not fundamental. They are how you organize your knowledge about what the propagation operator is doing.

Well, well... the path integral formulation is based on mathematics, not a diagram. But diagrams and mathematical formulations can be equivalent. For example, you can use regression or a machine learning algorithm to find a formula that fits a graph or geometrical shape. You can use the Schrödinger equation to visualize atomic orbitals, but you could probably also use a machine learning algorithm to find the Schrödinger equation from the shapes of the atomic orbitals.

You might think that graphs and geometrical shapes are "dumbed down" mathematics, but it is actually better to say that humans are much better at dealing with geometrical shapes than with mathematical formulas, since humans have a much larger part of the brain devoted to visual processing. A different species might be horrible at dealing with geometrical shapes, but much better than humans at processing mathematical formulas. A member of such a species, might think that mathematical formulas are "dumbed down" geometrical shapes.

Since humans haven't evolved to see 4 (or more) dimensional shapes, it is probably easier for humans to deal with the mathematics of 4 (or more) dimensional shapes, than to visualize them. So maybe we should consider the mathematics of a 4 (or more) dimensional shape to be a dumbed down geometrical shape?


Title: Re: Temporal information assymtery
Post by: Death 999 on August 23, 2018, 10:09:00 pm
And that math says that the two pictures, one with actual backwards time travel and one without, are equivalent.

Sure. I am not arguing that they aren't equivalent. But don't you get twice as many possibilities if you include both the forward possibilities and the backward possibilities? Why do you think the g-factor is around 2 and not around 1?

You need to include those in one way or another; taking the time-travel interpretation of the mathematics is not necessary.


And diagrams are not fundamental. They are how you organize your knowledge about what the propagation operator is doing.

Well, well... the path integral formulation is based on mathematics, not a diagram. But diagrams and mathematical formulations can be equivalent. For example, you can use regression or a machine learning algorithm to find a formula that fits a graph or geometrical shape. You can use the Schrödinger equation to visualize atomic orbitals, but you could probably also use a machine learning algorithm to find the Schrödinger equation from the shapes of the atomic orbitals.

You might think that graphs and geometrical shapes are "dumbed down" mathematics…

They don't need to be, but look at it this way - each diagram corresponds to an integral. Do you know what that integral is? In this sense, it is dumbed down. Important parts were left out. And when you look at those important parts, you find that there is no need to, and indeed, it hurts to, consider the action of antimatter to be traveling backwards in time.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 24, 2018, 10:59:18 am
They don't need to be, but look at it this way - each diagram corresponds to an integral. Do you know what that integral is? In this sense, it is dumbed down. Important parts were left out. And when you look at those important parts, you find that there is no need to, and indeed, it hurts to, consider the action of antimatter to be traveling backwards in time.

Feynman diagrams/integrals are used to predict the anomalous magnetic dipole moment.

Quote
In quantum electrodynamics, the anomalous magnetic moment of a particle is a contribution of effects of quantum mechanics, expressed by Feynman diagrams with loops, to the magnetic moment of that particle.

https://en.wikipedia.org/wiki/Anomalous_magnetic_dipole_moment (https://en.wikipedia.org/wiki/Anomalous_magnetic_dipole_moment)

As I have said earlier, this gives us one of the most accurate descriptions of reality we have today.

Quote
The QED prediction agrees with the experimentally measured value to more than 10 significant figures, making the magnetic moment of the electron the most accurately verified prediction in the history of physics.

https://en.wikipedia.org/wiki/Anomalous_magnetic_dipole_moment#Electron (https://en.wikipedia.org/wiki/Anomalous_magnetic_dipole_moment#Electron)

I don't quite understand how you can claim that one of the most accurate descriptions we have of reality today is leaving important things out. Do you have a better way to predict the anomalous magnetic dipole moment, which doesn't use Feynman diagrams/integrals? Without Feynman diagrams/integrals, it seems like you would be 10 decimal places farther away from predicting the g-factor.


Title: Re: Temporal information assymtery
Post by: Death 999 on August 24, 2018, 07:54:08 pm
This is getting incredibly frustrating.

FEYNMAN DIAGRAMS HAVE MORE THAN ONE INTERPRETATION.

You can see them as including backwards-time-traveling things, or you can NOT see them as including backwards-time-traveling things. The math and the consequences work out the same either way. As I've said what feels like six times.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 25, 2018, 01:23:43 am
This is getting incredibly frustrating.

No reason to be frustrated. We are just trying to figure out how reality works. I just wonder why you would expect a g-factor of 2.00231930436146 from the math with only forward time interactions, and not a g-factor of 1.00115965218.

(https://i.imgur.com/0weGpyH.png)



Title: Re: Temporal information assymtery
Post by: Death 999 on August 25, 2018, 04:19:33 am
Because the math is identically the same whether you have one kind of stuff going forward and backward in time or two kinds of stuff only moving forwards in time.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 25, 2018, 09:53:07 am
Because the math is identically the same whether you have one kind of stuff going forward and backward in time or two kinds of stuff only moving forwards in time.

The Friedmann equation also describes the universe pretty well, if you include a number for the amount of dark matter and a number for the amount of dark energy in the universe, but it doesn't explain what dark matter and dark energy is.

Similarly, the math might work out well by just doubling the g-factor you would expect from the magnetic moment of the electron and all possible virtual forward time interactions, but it doesn't necessarily explain why you need to double it. This isn't obvious. They really thought the g-factor should be around 1 before the Dirac equation.


Title: Re: Temporal information assymtery
Post by: Death 999 on August 26, 2018, 06:37:57 am
… what?

the consequences of Feynman diagrams being valid are far-reaching and affect waaaay more than the exact value of the g-factor. Moreover, I am not disputing their accuracy! Just, interpreting them does not require introducing backwards-propagation in time. There is a very good - preferred, even - physical interpretation of Feynman diagrams which does not change the predictions even one tiny bit from what you're talking about, yet also does not have any particles going back in time at all. You can include backwards-traveling particles if you want, and if you're only looking at the microscopic level. But when you zoom out to the point where entropy gets to be a consideration, you lose that option. That's just not compatible with what time means to us in our world.


Title: Re: Temporal information assymtery
Post by: Zanthius on August 27, 2018, 02:06:54 pm
But if we have multiple possible futures, I don't quite understand why we don't have alternate histories:

(https://i.imgur.com/EliI6eB.png)

Couldn't it be that we come from different configurations of the universes, that for some reason converged into the configuration of the universe we have today?



Title: Re: Temporal information assymtery
Post by: Death 999 on August 29, 2018, 05:18:21 pm
1) Whether we have multiple pasts is one of those cases where it's not entirely clear. We definitely have multiple intermediary pasts (in a similar way to how we have multiple futures) in simple cases like a two-slit experiment, but the distant past looks so much like a low-entropy initial condition that in order for us to have multiple terminal pasts, its being low-entropy would have to be an illusion.

2) You've zoomed out to the level where backwards time travel makes less sense. Like, how would the universe fill in those dots? Would it start in the past and work its way forward, except when it has antimatter it puts… just… that backwards? But each of these is a total configuration of all particles in the universe. How would you send just part of it back? How do you even get 'ahead' of antimatter? Does there need to be a path to the future that doesn't involve any antimatter and then you get to fill it in from the other end? But due to the whole thing with the anomalous dipole moment as you've seen and the renormalization group in general, every regular particle carries a very small amount of antimatter around with it (and vice versa).

If you don't take the 'flow of time is flow of information' route and everything is moving forwards, then you end up in contradictions and not knowing where information comes from. It ends up worse than IRS forms where they tell you to put numbers down on lines you've already filled out, because in that case it means you misread the instructions; if antimatter travels back in time, that's actually baked into the rules.