The idea of infinity has always fascinated me. The idea that a number can go on "forever" always seemed counter-intuitive. The various thought experiments regarding the concept of infinity always puzzled me. As a Christian, infinity represented to me a mark of God.

As I progressed through school numbers like pi always fascinated me. How an irrational number like pi (which went on forever) was always the same for every circle (no matter the size) literally blew my young mind.

Did anyone else have this experience?

Also learning about Georg Cantor and his theories were like reading stuff I always thought. Not because I had a superb intellect (not trying to boast here) just from an intuitive feeling I always had.

Also learning that astronomers discovered the universe is expanding.... and that the universe is finite... and time and space are the actually the same (according to relativity by Einstein)... how could anyone not believe we were created...

Sorry for the rambling... if anyone else had any scientific learning that expanded their religious experience please share!

I had the opposite experience the more I learned. I think that primarily had to do with cultural issues at the time: the Dover trial, intelligent design and creationism were all big news back then. The message that stuck with me at the time from all of that was that religion and science were at opposite ends of the spectrum. How they decided what was true and the conclusions they arrived at, especially on evolution, were so discordant that I thought I more or less had to pick one or the other. And as I learned just how incontrovertible the scientific evidence was for evolution, it really became an easy choice.

However, I do know what you mean regarding numbers. The two facts that really make me scratch my head are euler's formula and the integral of the Gaussian over the reals.

There's infinite numbers and then there are transfinite numbers - sets of infinite numbers.

Quote:

---

There's no reason to believe that the universe is finite

---

We know that the observable universe has a finite size and an accelerating rate of expansion. What reason do we have to assume the existence of more universe outside of what we can observe?

The observable universe is finite, of course. What about the rest of it?

What makes you so certain there is more that we can't observe? Not saying there isn't, but I'm curious how you're both so confident of the fact

Learning about Quantum Mechanics at the time I was still a believer but starting to doubt, definitely pushed me back into believing only a God could create reality in such a way that required our consciousness to perceive reality. Though there are many other interpretations of what QM tells us.

Texaggie7nine said:

---

Learning about Quantum Mechanics at the time I was still a believer but starting to doubt, definitely pushed me back into believing only a God could create reality in such a way that required our consciousness to perceive reality.

---

How does QM imply this?

The Copenhagen Interpretation

Are you familiar with the concept of decoherence?

Because the only thing that keeps us from seeing it are the facts that the universe is expanding, light has a speed limit and only 13.8 billion years to move toward us. The visible universe is a moving sphere.

dargscisyhp said:

---

Are you familiar with the concept of decoherence?

---

Yes. I understand more now, especially since no longer being a practicing christian, the other explanations that can rule out any need for a conscious observer.

However, I am still fascinated by it and think there is still a lot of argument to be made in favor of a conscious observer.

The arguments against it seem to mainly focus around the line of thought of "well it just doesn't seem right that that would be the case".

Within the Copenhagen interpretation, what feature of QM do you think demands a conscious observer?

How exactly would you have evidence of lack of inifinity?

We know on the other end that things are not infinitely divisible. Even space itself has Planck distance.

We also get into a lot of absurdities talking about infinites. For instance, if the universe has size and all parts contain matter (even if just spontaneous and annihilating pairs), then we'll have infinite matter. And infinite matter has infinite gravity. And we don't notice infinite gravity in the observable universe. Now you could use dark energy to offset gravity, but infinites don't really offset infinites. When comparing the effects of infinite dark energy to infinite gravity there's no logical way to resolve the conflict, other than just going off what we actually can observe.

I think this is some of what people talk about when they say that theoretical physicists are unwitting philosophers. Whether the universe if infinite or finite is an age old metaphysical question, and it by definition cannot be answered by the scientific method. I don't see how it would matter personally, but often metaphysics can have big impacts on other areas of philosophy including ethics and theology. I remember you arguing that theoretical physicists should be able to "stay in their lane" and feel no obligation to engage outside their specialty, but this particular instance seems to show that you can't help it.

Quote:

---

Because the only thing that keeps us from seeing it are the facts that the universe is expanding, light has a speed limit and only 13.8 billion years to move toward us. The visible universe is a moving sphere.

---

I'm honestly not trying to be snarky, but you do realize that you just expressed belief in an infinite, unobserved and unobservable entity?

dargscisyhp said:

---

Within the Copenhagen interpretation, what feature of QM do you think demands a conscious observer?

---

I wouldn't say "demands", but the theory of a conscious observer causing the collapse would easily explain things like the Quantum Eraser and Delayed Choice experiments.

I get that the act of measurement which entangles the particle with the measuring device particles, such as spin detection, can collapse the wave without any conscious observer but the fact that you can bring back interference by simply erasing the spin data by redirecting all particle spins in one direction seems counterintuitive because you are imparting collisions with other systems twice on the particle.

Same with the Delayed Choice by Kim et al.

Whether or not the universe is infinite has observable, measurable consequences. I therefore reject the assertion that the size of the universe is a metaphysical topic, and not a physical one.

Also, a minor quibble, but infinite series/integrals don't have to diverge. Infinite products don't have to diverge.

Quote:

---

Whether or not the universe is infinite has observable, measurable consequences. I therefore reject the assertion that the size of the universe is a metaphysical topic, and not a physical one.

---

I heartily disagree. We can certainly make scientific conclusions regarding what we can actually observe, directly or indirectly. However, making statements regarding things we suppose are real but are not observed and can never be observed is pretty much the definition of metaphysics

I expressed the notion that the reason we can't see it is understood to have nothing at all to do with what's there. That each and every location in the universe has its own observable universe.

So I consider it dramatically more likely that there is more out there that we cant see. I don't know about infinite or not or even if that's a coherent concept physically.

Texaggie7nine said:

---

dargscisyhp said:

---

Within the Copenhagen interpretation, what feature of QM do you think demands a conscious observer?

---

I get that the act of measurement which entangles the particle with the measuring device particles, such as spin detection, can collapse the wave without any conscious observer but the fact that you can bring back interference by simply erasing the spin data by redirecting all particle spins in one direction seems counterintuitive because you are imparting collisions with other systems twice on the particle.

Same with the Delayed Choice by Kim et al.

---

You might check out Cthuga's second post here: https://www.physicsforums.com/threads/resolution-to-the-delayed-choice-quantum-eraser.320334

Quote:

---

I expressed the notion that the reason we can't see it is understood to have nothing at all to do with what's there. That each and every location in the universe has its own observable universe.

---

Again, this is not a scientific statement. The idea that each and every location has it's own observable universe is certainly logical based on our observations, but it is still an extrapolation of things that we cannot and never will be able to observe.

I accept that you were not arguing for physical infinity, but even so you are very confidently arguing for the real existence of unobservable things.

ramblin_ag02 said:

---

Quote:

---

Whether or not the universe is infinite has observable, measurable consequences. I therefore reject the assertion that the size of the universe is a metaphysical topic, and not a physical one.

---

I heartily disagree. We can certainly make scientific conclusions regarding what we can actually observe, directly or indirectly. However, making statements regarding things we suppose are real but are not observed and can never be observed is pretty much the definition of metaphysics

---

We make inferences all the time based on what we know and observe, and we don't call it metaphysics. Your argument, carried to its logical conclusion, invalidates our justice system because the jury can never observe a crime, they can only infer based on evidence. Physicists do the same thing. Frankly, physical theories are a lot more precise and testable than evidence presented in the courtroom. I don't particularly care what term you want to use for what a jury does. If you want to call it metaphysics so be it. But that's a profoundly different type of thing than what Feser was talking about, if you're referring back to that other thread.

dargscisyhp said:

---

Texaggie7nine said:

---

dargscisyhp said:

---

Within the Copenhagen interpretation, what feature of QM do you think demands a conscious observer?

---

I get that the act of measurement which entangles the particle with the measuring device particles, such as spin detection, can collapse the wave without any conscious observer but the fact that you can bring back interference by simply erasing the spin data by redirecting all particle spins in one direction seems counterintuitive because you are imparting collisions with other systems twice on the particle.

Same with the Delayed Choice by Kim et al.

---

You might check out Cthuga's second post here: https://www.physicsforums.com/threads/resolution-to-the-delayed-choice-quantum-eraser.320334

---

Thank's. I'll have to take a look this evening when I have an hour or so to try to grasp it all, as I am pretty much ignorant with physics equations.

Do you have a similar explanation to explain the double slit quantum eraser experiment?

To me it seems, even with the post you linked, the common language of "if we have which way information the interference is destroyed" still promotes the idea that simply destroying the which way information, by any way, will bring back an interference pattern.

I have started to consider the many worlds interpretation to be more valid because they do seem to give proper respect to how our knowing the state of a particle, entangles our mind with the state of the particle and their only way to solve that issue is to say that there are as many versions of me as possible states of the particle that I can know.

Let me clarify what I mean. Evidence is evidence. We can use evidence in courtrooms to provide indirect observations of things that happened outside our direct experience. The same is true for the distant past, the very small, and the very distant. If you can observe the effects of something, even if you can't observe the thing, then I would consider that indirect observation and consider that as part of the observable universe. I also don't think that the observable universe is an absolute. 600 years ago the observable universe did not include the microscopic world or distant space, for instance. Even if those had observable effects, they were either not noticed or misattributed. So I'm not opposed to expansion or contraction of what we consider the observable universe.

When I speak of things that are not observed and cannot be observed, then I am speaking of things for which we have no evidence and can never have evidence. An example would be things are outside our light horizon and accelerating away from us faster than light speed due to cosmic expansion. We can never observe these things directly or indirectly in any currently conceivable way. So when we talk about things outside the observable universe, we are talking about things for which we have no evidence and never can. Making comments about such things is definitely outside the purveiw of science and squarely into the heart of metaphysics.

Quote:

---

OP was wrong, we can't know for sure whether there's a non-observable universe, and the rest of the argument is pretty pointless.

---

Spoken like a true empiricist

ramblin_ag02 said:

---

Quote:

---

I expressed the notion that the reason we can't see it is understood to have nothing at all to do with what's there. That each and every location in the universe has its own observable universe.

---

Again, this is not a scientific statement. The idea that each and every location has it's own observable universe is certainly logical based on our observations, but it is still an extrapolation of things that we cannot and never will be able to observe.

I accept that you were not arguing for physical infinity, but even so you are very confidently arguing for the real existence of unobservable things.

---

This is where you are clearly wrong. We will be able to observe this, just not on a scale of human lifetimes.

Basically, you claimed that the observable universe can be inferred as an actual border or boundary. This is absolutely not the case. I cannot prove there Is more beyond yet, but to call such a belief unscientific is asinine, as your conjecture was not scientific. The belief is highly logical, and not contradicted by any observable data. To attack a denial of your conjecture is quite weak on the grounds as no one has argued anything is proven only that we've not a single reason thus far to suspect the universe is confined in such a way.

Further, assuming the same laws occur throughout the universe is hardly unscientific.

The belief (whether rational/irrational, logical/illogical, consistent/inconsistent) in untested and untestable ideas is most certainly unscientific.

It isn't untestable and we can and have seen that the universe even at extreme distances operates on the same laws.

In regards to the universe having an end, this is not really questioned from what I have been told. It "ends". All material fabric of the "universe" ends at a certain point. Infinity does not exist in reality. However, what is beyond the universe could be a different material physical reality or something else entirely. But it is not the same "material" that makes up this universe. Our "material" has properties that follow strict rules.

I'm the son of an engineer and always had that engineering mindset. This is how I look at the concept of infinity.

A mathematician, a physicist and an engineer were all presented with the following problem.

"If you are standing six feet from a naked girl and each time you step towards her, you step 1/2 half the remaining distance. Will you ever reach the girl?"

The mathematician thought about this a while and answered; "No. This is a problem of infinite divisibility. You will approach the girl asymptotically, but you will never actually reach her."

The physicist said; "The mathematician is theoretically correct. With new experiments, we may discover quantum mechanics do not actually limit the minimal state of systems allowing for this possiblility."

They then asked the engineer what he thought. The engineer paused for a moment and said:

"Well, I may never actually reach the naked girl, but I'll get close enough to do what I want to do."

You have to be an engineer to know those things.