Yet, that statement requires much-needed justification! — Question

You need to study the scientific method. There is no justification, there are no "good reasons", such things are unobtainable and of no use.

I have yet to see proof that every physical law can be computed, which you (by the way) state as an absolute truth(?) Until then this is an unsubstantiated claim that you're throwing around here and there.

The latter. The way I would put this is to say that if the apple has form and matter then it is substantial. That is, it exists. — Andrew M

OK, I'm going to try to relate this to what you say about the apple, and about QM. I hope you understand, that to say the apple consists of matter and form, in the Aristotelian sense, is to invoke a type of dualism. You are saying that the apple consists of two distinct aspects, its matter and its form.
Under Aristotelian physics, the form of an object is what is active and changing, while there is an underlying matter which persists, and does not change.

At some point the apple grew on a tree and before that the tree grew from a seed. And in the other direction, at some point the apple will be eaten or decompose and perhaps its seeds will grow into into new trees. This is just matter changing form such that we can identify substances like apples. So the boundaries at the coming-into-existence and going-out-of-existence of an apple can be vague or ill-defined. But the apple is clearly identifiable when it is fully formed. And so we can develop language to talk about it. — Andrew M

Let's say that the apple is growing, ripening on the tree, so it is changing colours. It's form is changing. Do you believe that there is an underlying matter which is not changing? Of all the nutrients that the tree is putting into the apple, while it becomes sweeter and sweeter, is there really some underlying, "matter", which is not changing? If there is not some underlying "matter", which establishes continuity, the continued existence of the apple is not substantiated. We can call it "the apple" at one moment, but since it is changing, then unless we assume something underlying which is not changing, our claim that it is "the apple" at a later moment is unjustified.

When the molecular structure of the apple is changing over time, how can you say that 'this is just matter changing form"? Everything is changing, where is the "matter" which we assume is changing form? You can justify the claim that there is matter, by saying that there must be matter, because it remains "the same" apple. But the problem is that the existence of matter is just assumed in order to account for the apparent continuity of existence. So to now say that there must be such continuity, because there is matter, is circular reasoning. If we cannot validate the existence of matter, then we cannot justify that the apple continues to be the same apple despite changing, because we know that even the molecules and atoms are changing. When an apple tree comes into existence from a seed, and grows, how can this be matter changing form, if even the atoms and sub-atomic particles are changing?

To relate this back to QM. The formalism is the Schrodinger equation. The primary dispute is whether the equation is substantial. That is, is the wave function real? If it is, then that explains why we see interference effects. — Andrew M

Let me suggest to you that the concept of energy has replaced the concept of matter in most modern applications of physics, as the underlying thing which persists, and doesn't change, while the form which energy takes, actually changes. So we have the energy of the apple, rather than the matter, as the principle of continuity, this is firmly established by special relativity. Energy may come into the apple, and it may leave the apple, and as long as the amount is conserved, we have an underlying thing which doesn't change, the existence of that thing is substantiated through its energy.

I am not extremely familiar with the Schrodinger equation. I understand that it is closer to classical mechanics than it is to special relativity. Classical mechanics, being based in mass rather than energy, as the principle of continuity, is closer to the Aristotelian conception of matter, than the conception of energy in special relativity. Since substantial existence can be validated by any principle of continuity, whether it be mass (matter) or energy, then there should be no question as to whether or not the equation is "substantial". However, there may be inconsistencies between what is believed to constitute "substance".

No, if something is computable (doesn't encounter the Halting problem), then it is real in some sense. — Question

What sense is that? Does it have anything to do with what I asked? ("How can you possibly prove physical laws with a calculation?")

If something can't be computed then that is indicative of a gap in understanding or that there are some things that are unintelligible. — Question

How do you figure that? Do you even know what it means for something to be computable?

I have yet to see proof that every physical law can be computed, which you (by the way) state as an absolute truth(?) Until then this is an unsubstantiated claim that you're throwing around here and there. — Question

Try this

http://www.daviddeutsch.org.uk/wp-content/deutsch85.pdf

or Google

It is logically impossible to certify a physical law as true. This isn't news. — tom

If a physical law can't be certified as being true, how can it be computable?

Posted this question over at physicsforum:

https://www.physicsforums.com/threads/church-turing-deutsch-principle-and-incompleteness-halting.895072/

I'm considering contacting David Deutsch in regards to this question... I don't see any harm in doing that as this is quite an important question in my mind.

David Deutsch on twitter and always answers my questions there.

I'd at least try to read the paper I linked to though - the one where the CTD Principle is elucidated and the quantum computer invented. You are misrepresenting the CDT Principle, which makes you look like you don't begin to understand it.

I am reading it as we speak. I see no mention of the halting problem thus far...

Bingo!

(Sorry for the delay MU - life interrupting philosophy...)

I hope you understand, that to say the apple consists of matter and form, in the Aristotelian sense, is to invoke a type of dualism. — Metaphysician Undercover

Aristotle doesn't claim that two kinds of substance exist or that two kinds of properties exist, which is the usual sense of dualism. Instead substance (i.e., a thing that exists such as an apple) is an integration of matter and form.

If we cannot validate the existence of matter, then we cannot justify that the apple continues to be the same apple despite changing, because we know that even the molecules and atoms are changing. — Metaphysician Undercover

The simple explanation is that the apple's identity doesn't depend on its molecules and atoms being the same. Instead object persistence is implied when we talk about particular apples. What would be relevant is if someone secretly took the apple from the table and replaced it with a different apple.

So the issue is really about meaning and use, not justification.

Instead object persistence is implied when we talk about particular apples. — Andrew M

Talking about something does not cause the existence of the talked about thing.

The simple explanation is that the apple's identity doesn't depend on its molecules and atoms being the same. — Andrew M

So if such aspects of the apple are changing, then by what principle do we insist that the same apple continues to exist? We cannot just say "it is the same apple that it was yesterday", assuming that because we say that it is the same apple, therefore it is the same apple. We know that many things have changed, and therefore it really isn't the same apple. We need a principle to justify us saying that it is the same apple, so we can claim this to be the truth.

So the issue is really about meaning and use, not justification. — Andrew M

No, it's really a matter of justification. You can sit and watch the apple all day, and even see it change, without taking your eyes off it, so you know that no one has switched it. You know that it has changed, so you know that it is not the same apple. Yet we say that it is the same apple. Saying that it is the same apple does not cause it to be the same apple. So we need to justify this saying. What causes it to be the same apple, despite the fact that it has changed? We need to know this in order that we can be satisfied that what we are saying (it is the same apple) is the truth

No, it's really a matter of justification. You can sit and watch the apple all day, and even see it change, without taking your eyes off it, so you know that no one has switched it. You know that it has changed, so you know that it is not the same apple. Yet we say that it is the same apple. — Metaphysician Undercover

Yes we do. That's because object persistence is part of the ordinary concept of an apple.

Saying that it is the same apple does not cause it to be the same apple. — Metaphysician Undercover

That's correct, but the issue here is what is meant by the term "apple".

You're taking a particular time slice as constitutive of what it is to be an apple, like an individual frame in a film. But, in ordinary usage, the entire time line (or world line) is understood to constitute the apple.

To use the film analogy, it is the same film despite the fact that its frames are different. But there would be a legitimate issue if the second half of the film were replaced by frames from another film. This latter issue is where justification is relevant.

Yes we do. That's because object persistence is part of the ordinary concept of an apple. — Andrew M

Saying that temporal continuity, "object persistence", is part of the concept of the object, does not justify the assumption. That's like saying that the reason why I believe it, is because I believe it. Conceptions can be wrong. And that is the whole point here, we assume temporal continuity, but on what basis?

That's correct, but the issue here is what is meant by the term "apple". — Andrew M

No, that is not what is at issue here, you don't seem to get it. We know what is meant by "apple", or "object", temporal continuity is implied, but the question is whether or not this is a misconception. We know that the word "apple": is being used to refer to the appearance of a persistent similitude on the table. We know that the idea of temporal continuity is implicit with the concept of "apple", but the question is, is this temporal continuity real, or is it just an appearance. If it is just an appearance, then this is a misconception.

When I joined this discussion, what I questioned was the existence of the particle. I question the existence of the particle by the same principle that I question the existence of any object. If the assumed temporal continuity of the apple, or any object, is a misconception, then the same thing follows for the existence of the particle.

No, that is not what is at issue here, you don't seem to get it. We know what is meant by "apple", or "object", temporal continuity is implied, but the question is whether or not this is a misconception. We know that the word "apple": is being used to refer to the appearance of a persistent similitude on the table. We know that the idea of temporal continuity is implicit with the concept of "apple", but the question is, is this temporal continuity real, or is it just an appearance. If it is just an appearance, then this is a misconception. — Metaphysician Undercover

So help me out here. Do you think there is a causal basis for the apple on the table appearing as it does from moment to moment? Or do you think that, for all we know, it's just random coincidence?

So help me out here. Do you think there is a causal basis for the apple on the table appearing as it does from moment to moment? Or do you think that, for all we know, it's just random coincidence? — Andrew M

Clearly it's causal, an object cannot be random. Random existence is unintelligible but an object's existence is intelligible.

So on what grounds are you denying that apples exist? There is a distribution of particles following a world line that we can identify as the apple.

I've already explained my grounds, temporal continuity needs to be justified. If you're attempting to justify continuity with "a world line", then can you explain this concept to me?

I just did a quick read on Wikipedia and found that a world line applies to a point. Yet you referred to a "distribution of particles". So it appears impossible that a distribution of particles could follow a single world line.

I just did a quick read on Wikipedia and found that a world line applies to a point. Yet you referred to a "distribution of particles". So it appears impossible that a distribution of particles could follow a single world line. — Metaphysician Undercover

World lines apply to objects, whether particles or apples. The world line for an apple is the convergence of particle world lines.

That's a causal explanation. But in everyday life, it is intelligible to talk about an apple as persisting because we know its continued appearance is not random coincidence, whether or not a causal explanation is readily available. Which is sufficient justification for the claim that the apple exists.

World lines apply to objects, whether particles or apples. The world line for an apple is the convergence of particle world lines. — Andrew M

There is no such thing as the convergence of particle world lines, each is an individual. You could create an average, or a gravitational centre, but this requires another completely different assumption.

That's a causal explanation. But in everyday life, it is intelligible to talk about an apple as persisting because we know its continued appearance is not random coincidence, whether or not a causal explanation is readily available. Which is sufficient justification for the claim that the apple exists. — Andrew M

OK, I accept this, because you recognize that a cause may be needed. Let me put aside the question of whether or not you are actually convinced of the necessity to assume such a cause, and proceed under the assumption that it is necessary. We can take the traditional approach now, and assume that the cause is God. This is Newton's approach in the first law of motion. The continued existence of the object is simply assumed, guaranteed by the Grace of God, as the most divine Gift, existence. But don't you agree that the true philosophical approach, and consequently the scientific approach, would be to attempt to determine and understand the activities of this cause?

If we proceed, while holding the belief that there is necessarily a cause of temporal continuity, how could we integrate this cause into what we observe as the continued existence of the apple? Isn't it necessary to assume that at each moment of time, there is a cause which acts, to ensure that the apple will appear in a way similar to how it appeared in the last moment. Any change to the apple would be caused by an interference with this divine cause. This could be an interaction with other objects, each object having its own cause of temporal continuity, the will of God acting within each object individually.

But what constitutes a moment of time? This divine cause has been described above, as acting between moments of time, such that at each moment of time, the apple has continued existence. What happens when we divide the duration of time into shorter and shorter periods? At some point, we will reach a period of time which is so short, that this cause has not had time to act. What do you think we would observe in this short period of time, pure randomness? Perhaps you would expect to see that if you forgot about this cause. But if you believe in this cause, then you would expect to find it in action.

There is no such thing as the convergence of particle world lines, each is an individual. You could create an average, or a gravitational centre, but this requires another completely different assumption. — Metaphysician Undercover

You can approximate the apple as a point, or treat it as an extended volume (which would be a world tube) or aggregate the segments of the individual particle world lines that converge.

But don't you agree that the true philosophical approach, and consequently the scientific approach, would be to attempt to determine and understand the activities of this cause? — Metaphysician Undercover

Sure, we should try to figure out what the cause is. My only point is that we don't need to doubt the existence of the apple just because we don't know what that specific cause is. We know there is a cause (because it's not random coincidence), but it may be that no-one can explain exactly what it is or perhaps our current best explanation will end up being overturned tomorrow. Regardless, we can continue to intelligibly identify apples as existents in everyday life just as we always have.

Sure, we should try to figure out what the cause is. My only point is that we don't need to doubt the existence of the apple just because we don't know what that specific cause is. — Andrew M

It's not that we must doubt the existence of objects if we do not know the cause. You know we can live without knowing the cause. But if we want to find out the cause, then we must doubt the existence of the object. By doubting it, we express recognition that its existence is contingent. The question which naturally follows is "contingent on what?". So we proceed to seek that cause. If we take the existence of the object for granted, then we assume that it's existence is necessary, so long as it exists according to the laws of nature, which are induced from its observe existence. We state the law to the best of our knowledge, and we circumvent the question of why does the object exist, by converting it to "why does the object act according to the law?". This is answered with "because it exists" (existence being taken for granted). Existence appears as a necessity because it is the premise for logical procedure. Therefore it is not doubted, it is not seen as contingent, and the cause is not sought.

Sean Carroll makes a good case for MWI. It might even turn out to be the case that there are multiple universes. Time will tell.

I won't say, "I believe it's true." But, the concept does appear to have some usefulness.