The phenomenon and the explanation

partinobodycular said:

Does physical reality give rise to consciousness, or does consciousness give rise to physical reality?

Click to expand...

The physicist and the mystics each will give different answers to that question because they look at it from different directions.

SelfSim said:

The scientific method allows for us to distinguish between what you're referring to there as 'subjective' reality, when some perceptual model is found as being untestable. They are simply called called 'beliefs'.

Click to expand...

As Human Beings, we are incredibly subjective creatures. Everything we do is subjective, be it art, dance, our feelings, our expressions, inner thoughts, political views, religion, the path we take when we walk, the words we speak, the people we're attracted to, the awareness we experience when seeing a rainbow...most everything we do is subjective in nature. Everyone of us lives in a subjective world. It's one of the things that we experience as the Human experience. Now, are you saying that the Human experience is merely a "belief"? That this whole thing is an illusion?

dlamberth said:

As Human Beings, we are incredibly subjective creatures. Everything we do is subjective, be it art, dance, our feelings, our expressions, inner thoughts, political views, religion, the path we take when we walk, the words we speak, the people we're attracted to, the awareness we experience when seeing a rainbow...most everything we do is subjective in nature. Everyone of us lives in a subjective world. It's one of the things that we experience as the Human experience. Now, are you saying that the Human experience is merely a "belief"?

Click to expand...

No.
To do so, would be a conflation of science's objective process (and its tested outcomes), with beliefs.

dlamberth said:

That this whole thing is an illusion?

Click to expand...

Overall, you seem to be asking me for my model of how my brain and its environment work(?) I can tell you, (eg: as @FrumiousBandersnatch has done), but of course I'll just be giving you the way my brain makes sense of your question.

The model which artificially separates our brains from what is giving our brains their stimulus, denies the evidence that our brains actually actively participate in that same process of stimulation.
The denial there, is based on a belief that there exists that separation. Its a belief because there is no objective test/results which can demonstrate that supposed separation independently of the involvement of some human mind.
Science can come up with models there, for the purposes of making predictions, but those models obviously include the participation of actively participating, scientifically thinking brains/minds which therefore, does not demonstrate the artificial separation claimed to exist.

I suspect the way you're distinguishing 'illusion' in your above question, is by way of comparing our experiences, against some 'thing' that you believe exists independently from our minds that might tell us somehow, that its an illusion .. which is just your belief (for the above given reason).

SelfSim said:

The model which artificially separates our brains from what is giving our brains their stimulus, denies the evidence that our brains actually actively participate in that same process of stimulation.
The denial there, is based on a belief that there exists that separation. Its a belief because there is no objective test/results which can demonstrate that supposed separation independently of the involvement of some human mind.
Science can come up with models there, for the purposes of making predictions, but those models obviously include the participation of actively participating, scientifically thinking brains/minds which therefore, does not demonstrate the artificial separation claimed to exist.

Click to expand...

I have no idea what separation your alluding to here. Can you clarify? I'm thinking that it's not only our brains that are involved in Life, but our whole being as a Human Being participates in it.

I suspect the way you're distinguishing 'illusion' in your above question, is by way of comparing our experiences, against some 'thing' that you believe exists independently from our minds that might tell us somehow, that its an illusion .. which is just your belief (for the above given reason).

Click to expand...

Your projecting again.
I was just following where the logic led from what I understood in the words you wrote, and asked for clarification.

I'll try again with this. Do I actually experience a bit of aweness when seeing a rainbow? See Double Rainbow Guy Video An aweness experience is a very subjectivity experience, that's especially true in the video. But experiences like that are very Human. I'd even say it's one of the things that makes us Human Beings. Because of it's subjectivity, does that than makes the inner experience of aweness a "belief"? If only a belief, that means it's not an actual experience and is something else all together. So I asked, is that something else an "illusion?"

sjastro said:

I’m afraid you have misunderstood my post.
What I stated was that momentum is not conserved in pair production in the absence of external matter.
Pair production is where the photon λ produces a positron electron pair e⁺e⁻ according to the reaction;

λ → e⁺ + e⁻

The momentum p(λ) = E/c for a photon is clearly not zero.
For momentum to be conserved in this reaction;

E/c = m(e⁺)v₁ + m(e⁻)v₂

where m(e⁺)v₁ and m(e⁻)v₂ are the electron and positron momentum at velocities v₁ and v₂ respectively, m(e⁺) and m(e⁻) are the relativistic masses.
The reaction never occurs in a vacuum as momentum is not conserved since;

E/c ≠ m(e⁺)v₁ + m(e⁻)v₂.

It requires external matter of mass m such as a nucleus so that momentum is conserved according to the equation;

E/c = m(e⁺)v₁ + m(e⁻)v₂ + mv.

where mv is the momentum of the nucleus and v is its recoil velocity.

Furthermore in pair production the momentum of the electron and positron never cancel each other out.
This can only occur if they travel in opposite directions.
It would also imply E/c = mv which is clearly false as the recoiling nucleus would gain all the photon momentum.
For the conservation of momentum to occur in the presence of the nucleus the positron and electron move in the same general direction as the incident photon and therefore do not cancel each other out.

Click to expand...

Interesting. Link please.
\
EDITL Never mind. I was thinking of a different reaction. When two photons collide they can create matter. But it involves a different Feynman diagram than the one presented. I was thinking of the sort of reaction that made the first matter shortly after the start of the Big Band.



I do believe that is the diagram that demonstrates such a reaction. The straight line on the upper right is a normal particle and the one in the lower right is the anti particle:

Two-photon physics - Wikipedia

dlamberth said:

I have no idea what separation your alluding to here. Can you clarify?

Click to expand...

I already did .. In different words this time: I was referring to the idea that our brains/minds somehow exist independently from some separate, so-called 'external' source of stimulii. No, our brains/minds are inseparable from the sensory stimulii they experience. Our senses are an integrated part of our minds, but we happen to regard them as being separate.
In science, they're testable models, constructed to ultimately make predictions, so brain/mind and sensory organ/sense are just two different types of models .. but they're still both demonstrably, models. There is no need to refer to some separate so-called 'external source' of the stimulli .. that bit is just a pure, untestable belief .. and impacts nothing as far as objective reality and testing is concerned.

dlamberth said:

Your projecting again.

Click to expand...

That should read "you're" and not: 'your' (for the second time, now).
I am not projecting. You just don't understand how the words you write acquire their meanings. How could you possibly conclude, from anything I've said, that life is 'an illusion'? Why would you even ask me why I'd think 'human experiences' (or life) are an illusion, when I'm fully aware of how that very term, ie: 'illusion', is distinguished, as follows .. by:
i) comparing experiences with other people's and seeing if they're experiencing the same thing and by;
ii) ascertaining whether there's evidence that what's being experienced isn't either consistent with the rules of logic, or isn't consistent with known science.

If (i) returns a negative, then its worse than an illusion .. its more like a delusion.
If (ii) returns a positive, then its an illusory belief being experienced.

Both (i) and (ii) involve testing, which is a process leading towards informing us what some experience is (or simply - its meaning).
This is what I'm saying is how we decide what exists and what doesn't. There is no need for words like internal, external or physical, non physical or even material, non material. Those words are completely useless for finding out because they mean different things to different people and thus fail on consistency.

dlamberth said:

I'll try again with this. Do I actually experience a bit of aweness when seeing a rainbow? See Double Rainbow Guy Video An aweness experience is a very subjectivity experience, that's especially true in the video. But experiences like that are very Human. I'd even say it's one of the things that makes us Human Beings. Because of it's subjectivity, does that than makes the inner experience of aweness a "belief"? If only a belief, that means it's not an actual experience and is something else all together. So I asked, is that something else an "illusion?"

Click to expand...

I can test if 'awe' is present or not, by simply asking another person to describe what they're experiencing. If it matches my own, then its not just an individual's own subjective experience any more, is it?

Subjectivity and objectivity aren't clear-cut and pre-determined by some dictionary definition. All dictionaries do, is give some fuzzy general approximation of what people sometimes mean when they use such terms, but their meaning is always dependent on the contexts in which they're used. One has to do the hard yards and find out what is meant there and the scientific method does it better than the other way .. which is just making stuff up (or reading from a dictionary) and then just go on believing that.

Dictionary or web definitions for what 'objectivity' means are actually quite a mess .. what one generally sees, is people bending over so far backward to try to interpret "objectivity" in a mind-independent way, that the meanings they intend end up being clearly internally inconsistent, which is easy to demonstrate - I've done it before and seen that for myself. But you have to actually make the attempt and actually execute that test and experience that for yourself.

SelfSim said:

And this is where you are being inconsistent. Objective reality is what the objective method, via tested/operational scientific models, produces. Those models are entirely conceived (and tested) by scientifically thinking minds, via the scientific method.

There is no objective evidence which allows for distinguishing between so called 'internal' and 'external' reality. Both are demonstrably, perceptual constructs formed by healthy human minds.

The scientific method allows for us to distinguish between what you're referring to there as 'subjective' reality, when some perceptual model is found as being untestable. They are simply called called 'beliefs'.

Click to expand...

I'm using conceptual language that (I hope) partinobodycular and others here are familiar with and will understand.

Subduction Zone said:

Interesting. Link please.
\
EDITL Never mind. I was thinking of a different reaction. When two photons collide they can create matter. But it involves a different Feynman diagram than the one presented. I was thinking of the sort of reaction that made the first matter shortly after the start of the Big Band.

I do believe that is the diagram that demonstrates such a reaction. The straight line on the upper right is a normal particle and the one in the lower right is the anti particle:

Two-photon physics - Wikipedia

Click to expand...

Your Feynman diagram is the two photon production for the annihilation of matter and antimatter.

sjastro said:

Your Feynman diagram is the two photon production for the annihilation of matter and antimatter.

Click to expand...

It also works in reverse.

FrumiousBandersnatch said:

I'm using conceptual language that (I hope) partinobodycular and others here are familiar with and will understand.

Click to expand...

And I appreciate it.

FrumiousBandersnatch said:

I'm using conceptual language that (I hope) partinobodycular and others here are familiar with and will understand.

Click to expand...

But ultimately, misleading.

You can file this under another stupid question from partinobodycular.

In the double slit experiment MWI argues that upon measurement the wave function branches into two separate worlds, both of which actually exist. To simplify the experiment, what if we remove one of the slits. Then isn't the screen itself acting as a measuring device? With each point on the screen representing a different possible outcome. Thus in keeping with MWI's argument shouldn't we treat each of those possible outcomes as a real world?

In other words, if, when there are two possible outcomes MWI treats them both as real, then shouldn't MWI, when there are multiple possible outcomes, treat them all as real?

Subduction Zone said:

It also works in reverse.

Click to expand...

Actually it doesn't.

Electron/positron annihilation;
e⁻ + e⁺ → γ + γ

Pair production;
γ → e⁻ + e⁺

The reason why two photons are produced in the annihilation process is because it is not instantaneous and can exist in a short lived state known as positronium.
In this state the momentum of the electron and positron are zero.
In order for momentum to be conserved, two photons are created which travel in opposite directions so their total momentum is zero.

sjastro said:

Actually it doesn't.

Electron/positron annihilation;
e⁻ + e⁺ → γ + γ

Pair production;
γ → e⁻ + e⁺

The reason why two photons are produced in the annihilation process is because it is not instantaneous and can exist in a short lived state known as positronium.
In this state the momentum of the electron and positron are zero.
In order for momentum to be conserved, two photons are created which travel in opposite directions so their total momentum is zero.

Click to expand...

I disagree, especially since I got that from an article on gamma ray to gamma ray collision. I misused the term pair production earlier myself. This is not traditional pair production. From my understanding it is the sort of every early universe collisions that ultimately led to matter. Essentially hydrogen and electrons. There is still some question on why there is a matter versus antimatter imbalance. But very early on there was no matter in the universe according to the Big Bang theory.

Two-photon physics - Wikipedia

In theory I do believe that all Feynman diagrams could go either way. But I may be mistaken.

partinobodycular said:

In the double slit experiment MWI argues that upon measurement the wave function branches into two separate worlds, both of which actually exist.

Click to expand...

Not necessarily two worlds. The wavefunction branches into as many worlds as there are possible places for the particle to be detected. The interference pattern corresponds (roughly) to those possibilities.

To simplify the experiment, what if we remove one of the slits. Then isn't the screen itself acting as a measuring device? With each point on the screen representing a different possible outcome. Thus in keeping with MWI's argument shouldn't we treat each of those possible outcomes as a real world?

Click to expand...

The screen is the measuring device whether there are two slits or one. And yes, when the particle goes through a single slit, its wavefunction forms a diffraction pattern, and every possible detection outcome on the screen creates a separate world branch.

In other words, if, when there are two possible outcomes MWI treats them both as real, then shouldn't MWI, when there are multiple possible outcomes, treat them all as real?

Click to expand...

It does.

FrumiousBandersnatch said:

Not necessarily two worlds. The wavefunction branches into as many worlds as there are possible places for the particle to be detected. The interference pattern corresponds (roughly) to those possibilities.

The screen is the measuring device whether there are two slits or one. And yes, when the particle goes through a single slit, its wavefunction forms a diffraction pattern, and every possible detection outcome on the screen creates a separate world branch.

It does.

Click to expand...

First let me say, that whether anyone responds to my stupid questions or not, I really appreciate simply being allowed to ask them. I've been on "Physics Forums" for years, and they strongly discourage stupid questions. So simply being allowed to ask them, and actually having someone respond is awesome. So Thanks.

Okay, now on to stupid question number two.

This question has to do with branching. In the double slit experiment MWI seems to say that when we make a measurement, reality splits into two distinct yet equally real branches. On the face of it this seems to violate the conservation of energy, so MWI, or at least Sean Carroll and others get around this by "weighting" the branches. This seems very, very contrived to me. I think that it would be much simpler if we just assumed that those branches were there all along, and that they existed from the very moment that the particle was emitted. They weren't somehow "created" at the point of measurement. But I would go even further than that. In Richard Feynman's "sum over histories" we're told to imagine the particle as taking every possible path from the emitter to the screen. I would argue that that really does happen, and that the particle really does take every path, even the ones that don't ultimately make it to the screen. Each possible path represents a real world.

Now I don't know if this is just confusion on my part about what MWI says, but it just seems to make sense to me, and of course it's going to lead to stupid question number three.

partinobodycular said:

First let me say, that whether anyone responds to my stupid questions or not, I really appreciate simply being allowed to ask them. I've been on "Physics Forums" for years, and they strongly discourage stupid questions. So simply being allowed to ask them, and actually having someone respond is awesome. So Thanks.

Click to expand...

My view is that there are no stupid questions, only honest and dishonest questions.

In the double slit experiment MWI seems to say that when we make a measurement, reality splits into two distinct yet equally real branches.

Click to expand...

Again, not two branches, but as many branches as there are possible measurement outcomes at the screen (which is a lot).

On the face of it this seems to violate the conservation of energy, so MWI, or at least Sean Carroll and others get around this by "weighting" the branches.

Click to expand...

No, the weighting is not concerned with the conservation of energy but with the distribution of the available energy in relation to the probability of any particular outcome (from the Born rule). The branches are just superpositions of the universal wavefunction. The total energy of the universal wavefunction is the same after branching as before, and the energy is divided between the branches. But the question is how the energy is allocated between them, and it seems reasonable to do it according to their initial wavefunction amplitudes.

This seems very, very contrived to me. I think that it would be much simpler if we just assumed that those branches were there all along, and that they existed from the very moment that the particle was emitted. They weren't somehow "created" at the point of measurement. But I would go even further than that. In Richard Feynman's "sum over histories" we're told to imagine the particle as taking every possible path from the emitter to the screen. I would argue that that really does happen, and that the particle really does take every path, even the ones that don't ultimately make it to the screen. Each possible path represents a real world.

Click to expand...

Sure; I think that's a perfectly valid way to think of it. The branches are there all along but they're identical until that particular quantum interaction occurs, at which point they diverge. The end result is the same.

Note: my responses here are my best understanding of the topic - I can't guarantee they're correct. I'm happy to be corrected by someone who can give an authoritative reference or convincing explanation.

Subduction Zone said:

I disagree, especially since I got that from an article on gamma ray to gamma ray collision. I misused the term pair production earlier myself. This is not traditional pair production. From my understanding it is the sort of every early universe collisions that ultimately led to matter. Essentially hydrogen and electrons. There is still some question on why there is a matter versus antimatter imbalance. But very early on there was no matter in the universe according to the Big Bang theory.

Two-photon physics - Wikipedia

In theory I do believe that all Feynman diagrams could go either way. But I may be mistaken.

Click to expand...

In your link most of the mechanisms involved are fermion/antifermions virtual pairs which are created and destroyed in the two photon reactions unlike the free electron and positrons in the pair production from a single photon.

I misread your Feynman diagram as this;


Unfortunately there doesn’t seem to any general agreement on how the axes are assigned and in your example the time axis is along the horizontal and is an example of photon annihilation.


The reverse reaction (reading the diagram from right to left) for an positron electron pair producing two photons cannot occur in the early universe due to the extremely high temperatures where the relativistic masses of the positron and electron are mostly taken up as the kinetic energy.
For photon pairs to be produced the rest mass energies of the positron and electron dominate, for higher energies a range of other particles are formed.


The other point that needs to be considered involves the energy momentum equation developed by Einstein in special relativity E² = (pc)² + (m₀c²)².
‘Real’ bosons such as photons meet this equation where m₀ = 0 (as ‘real’ photons are massless), hence E = pc.
The single photons which produce electron/positron pairs are ‘real’.
‘Virtual’ photons however do not meet this equation and can have mass.
Particle physicists are not even sure whether the two photon collisions used in their experiments to produce electron/positron pairs are ‘real’ or ‘virtual’.
If the photons are ‘virtual’ like their fermion counterparts they exist very briefly and therefore do not represent ‘real’ photons in our universe.
https://www.sciencenews.org/article/colliding-photons-matter-particle-physics