Ask a physicist anything. (6)

[Chalnoth]

Why not?

Well, it's basically like dividing by zero. If you divide by zero, you can prove anything in arithmetic to be true. There's a classic proof where, utilizing a division by zero, you can demonstrate that 1=2. The only way around this is by explicitly stating that division by zero isn't allowed.*

But when we're talking about a physical theory, you can't "hide" the division by zero in the same way. You can't tell reality to just not do something: it will do whatever the laws of nature say it can do. So if you have a division by zero (a singularity), you have a big problem: you can use that singularity to, in principle, do anything at all, and so the whole theory collapses.

*As an addendum, you may be thinking here of calculus, where we routinely make use of zeroes and infinities. But if you look at these carefully, you actually don't have real division by zero or real infinities: these are taken as limits, so that there aren't any actual divisions by zero, for example, when taking a derivative to get a sensible result.

 

[razeontherock]

I suppose it could be too much to ask to be able to go to people like Pat Robertson, press a button, and say "Nope, you're as spiritually dead as me. Sorry, buddy"

Now that, is funny!

What about the argument that Jesus renamed Simon as 'Peter' as a reference to the 'rock'? I've always found the Catholic argument that the line of popes start here to be quite persuasive.

Ok. There are 2 different trains of thought that pop into my head. 1) You have big rock vs little rock. Peter is the little rock. The Rock Jesus builds His Church on is the big Rock. We could talk about how someone 2000 years from now might pick up a newspaper article about sports teams and get the wrong idea to a hilarious extent, but then there are people who speak Koine Greek. Right on this forum! Not in the RCC though. Those guys spoke Latin.
So on such a matter, I'm more inclined to listen to the native Greek speakers than those going through many languages to translate, knowing that at each step something does get lost. Still, I don't know enough about Greek to really trust my judgment on this.

2) Rome was 1 Church, founded considerably after the first Church, which was in Jerusalem. Now how in the world you can say that by the year 1054 there were "only 5 major Churches," I really don't understand. Yet this is accepted history. So in the big split of 1054, Rome severed herself from the other 4 Churches, and one big issue was the Pope claiming supremacy for himself. A commonly cited habit of Rome is "adding new doctrine," which partly alludes to making up this pope thing. If it was one or 2 Churches separating from the Pope I might give credence to Rome, but under these circumstances it's a transparent power grab by Rome. Yick. They have a long history of that sort of thing, right?

So both these issues point to the same thing. I'm only aware of one other facet that may have some tangential relevance: RCC likes to trace it's lineage of Popes back to Peter. Cool right? Except when you examine the various accounts, they don't agree. Not only that, but the historians of the period in question (immediately following Peter til say 150) don't really make a point to record any such succession! This tells me it wasn't important. Not until later, anyway. And when such aspects of record keeping became really important, was when Constantine came on the scene. So yeah, I smell a rat.

 

[razeontherock]

It's a good idea, but I disagree with the last line: "Information is always based on an idea; it is thus also massless and does not arise from physical
or chemical processes". I would say that information can arise from physical or chemical processes, depending on what one means by 'information'. I believe the complexity of DNA arose all by itself, and since DNA arguably contains vast quantities of information, information can therefore arise by itself.

Calling this information a 'soul', be it in DNA or in the brain, may work, but I think it deprives the word of its inevitable spiritual component, that essence of being somehow qualitatively different, of being 'other' than the mundane body.

I find this reasonable, and internally consistent. You write off information theory as bunk? I do think info starts w/ something other than arising from itself, or at least intelligent info does, but this basic difference between you and I is predictable based on just looking at our respective icons.

And I agree, such a definition of soul can't be complete. Pretty sure a Christian poster on CF invented that part, and it surprised me to see it.

 

[razeontherock]

Evolutionary systems are not isolated systems.

Well the ecosystem as a whole is isolated, if only by virtue of Earth's atmosphere. But we surely take in heat and radiation from the sun. Still, saying that can slow down entropy doesn't really jibe with disorder arriving at order ...

 

[Chalnoth]

Well the ecosystem as a whole is isolated, if only by virtue of Earth's atmosphere. But we surely take in heat and radiation from the sun. Still, saying that can slow down entropy doesn't really jibe with disorder arriving at order ...

It's the cycle of heat from the Sun that allows life on Earth to exist. We take in energy during the day, and release it during the night. This is why nearly all life on the Earth relies, ultimately, upon energy derived from the Sun.

Now, you might be able to argue that the Earth/Sun system is effectively a closed system (the Earth alone certainly is not). But there the entropy of the Sun increases far, far more than the entropy of life on Earth needs to decrease for life to exist and propagate. So in total, there is an entropy increase.

 

[Wiccan_Child]

Well the ecosystem as a whole is isolated, if only by virtue of Earth's atmosphere. But we surely take in heat and radiation from the sun. Still, saying that can slow down entropy doesn't really jibe with disorder arriving at order ...

There is a local decrease in entropy due to light shining down from the Sun, but this light is created by a corresponding increase in entropy. The Sun increases entropy far more than any local decrease on the Earth.

 

[Wiccan_Child]

Well, it's basically like dividing by zero. If you divide by zero, you can prove anything in arithmetic to be true. There's a classic proof where, utilizing a division by zero, you can demonstrate that 1=2. The only way around this is by explicitly stating that division by zero isn't allowed.*

But when we're talking about a physical theory, you can't "hide" the division by zero in the same way. You can't tell reality to just not do something: it will do whatever the laws of nature say it can do. So if you have a division by zero (a singularity), you have a big problem: you can use that singularity to, in principle, do anything at all, and so the whole theory collapses.

*As an addendum, you may be thinking here of calculus, where we routinely make use of zeroes and infinities. But if you look at these carefully, you actually don't have real division by zero or real infinities: these are taken as limits, so that there aren't any actual divisions by zero, for example, when taking a derivative to get a sensible result.

Isn't the singularity of the Big Bang a limit as well, though? It's whatever happens when matter does something that tends to infinity, such as when matter is squeezed into its own Schwarzchild radius. Similarly, the singularity of the Big Bang is, as you undoubtedly already know, derived by looking at the recession velocities and working backward. The further back, the denser everything is. Who's to say that all the matter in the universe cannot be compacted into a single point? So, I don't think it's division by zero per se. Who knows, I may be wrong

GR says that things can be infinitely dense, and QM says that things can be at most enormously, but still finitely, dense. I think that conflict shows that both cannot be true, and I think QM is more on the money than GR. But, that said, I don't think the infinite singularity is itself impossible.

 

[Wiccan_Child]

Ok. There are 2 different trains of thought that pop into my head. 1) You have big rock vs little rock. Peter is the little rock. The Rock Jesus builds His Church on is the big Rock. We could talk about how someone 2000 years from now might pick up a newspaper article about sports teams and get the wrong idea to a hilarious extent, but then there are people who speak Koine Greek. Right on this forum! Not in the RCC though. Those guys spoke Latin.
So on such a matter, I'm more inclined to listen to the native Greek speakers than those going through many languages to translate, knowing that at each step something does get lost. Still, I don't know enough about Greek to really trust my judgment on this.

2) Rome was 1 Church, founded considerably after the first Church, which was in Jerusalem. Now how in the world you can say that by the year 1054 there were "only 5 major Churches," I really don't understand. Yet this is accepted history. So in the big split of 1054, Rome severed herself from the other 4 Churches, and one big issue was the Pope claiming supremacy for himself. A commonly cited habit of Rome is "adding new doctrine," which partly alludes to making up this pope thing. If it was one or 2 Churches separating from the Pope I might give credence to Rome, but under these circumstances it's a transparent power grab by Rome. Yick. They have a long history of that sort of thing, right?

So both these issues point to the same thing. I'm only aware of one other facet that may have some tangential relevance: RCC likes to trace it's lineage of Popes back to Peter. Cool right? Except when you examine the various accounts, they don't agree. Not only that, but the historians of the period in question (immediately following Peter til say 150) don't really make a point to record any such succession! This tells me it wasn't important. Not until later, anyway. And when such aspects of record keeping became really important, was when Constantine came on the scene. So yeah, I smell a rat.

Hmm, that's quite interesting. Thanks for giving me a non-Catholic view The whole 'scripture plus tradition' thing always strikes me as a bit dubious. Of all the Christian denominations, I think I like Catholicism the most, because it doesn't pull its punches, make allowances, or wring its hands over difficult issues - but I guess I'm just a sucker for all the pomp and ceremony

I find this reasonable, and internally consistent. You write off information theory as bunk? I do think info starts w/ something other than arising from itself, or at least intelligent info does, but this basic difference between you and I is predictable based on just looking at our respective icons.

True 'dat.

And I agree, such a definition of soul can't be complete. Pretty sure a Christian poster on CF invented that part, and it surprised me to see it.

I can see why he might adopt that idea, because it's quite tantalizing to have a real, working model of what the soul actually is. But you'd think, if nothing else, it has to have something 'different' to the body, rather than be just a manifestation of it.

 

[Chalnoth]

Isn't the singularity of the Big Bang a limit as well, though? It's whatever happens when matter does something that tends to infinity, such as when matter is squeezed into its own Schwarzchild radius. Similarly, the singularity of the Big Bang is, as you undoubtedly already know, derived by looking at the recession velocities and working backward. The further back, the denser everything is. Who's to say that all the matter in the universe cannot be compacted into a single point? So, I don't think it's division by zero per se. Who knows, I may be wrong

No, it is an actual singularity. For one thing, this means that if you took the state of the universe at that point, you could conclude anything at all about the state of the universe at another time.

The singularity at the center of black holes, by the way, is also expected to just be an artifact of General Relativity, and that a quantum theory of gravity won't display a singularity.

Another way of looking at this is that General Relativity has a built-in energy scale: the Planck mass, and naive attempts at quantizing gravity say that quantum effects should come in at roughly that scale. But if you have a singularity, you are going well above the Planck scale in terms of energy, so you simply cannot take GR seriously at those levels.

GR says that things can be infinitely dense, and QM says that things can be at most enormously, but still finitely, dense. I think that conflict shows that both cannot be true, and I think QM is more on the money than GR. But, that said, I don't think the infinite singularity is itself impossible.

Well, I wouldn't say that GR says that things can be infinitely dense. GR has infinitely dense things in the theory, but there are multiple reasons to believe that it's wrong about this.

 

[Wiccan_Child]

No, it is an actual singularity. For one thing, this means that if you took the state of the universe at that point, you could conclude anything at all about the state of the universe at another time.

The singularity at the center of black holes, by the way, is also expected to just be an artifact of General Relativity, and that a quantum theory of gravity won't display a singularity.

Another way of looking at this is that General Relativity has a built-in energy scale: the Planck mass, and naive attempts at quantizing gravity say that quantum effects should come in at roughly that scale. But if you have a singularity, you are going well above the Planck scale in terms of energy, so you simply cannot take GR seriously at those levels.


Well, I wouldn't say that GR says that things can be infinitely dense. GR has infinitely dense things in the theory, but there are multiple reasons to believe that it's wrong about this.

Right: it says that things can be infinitely dense (such as what happens to matter in a black hole), but there are reasons to believe that it's wrong at these scales. I agree that GR is wrong when it says that there are actual infinities, but only because that conflicts with QM. But, I'm not convinced that it's impossible to have, say, infinitely dense matter. It may be impossible in practice due to various physical laws, but I don't see why it can't possibly happen. Surely we can model things in such a way that true infinities pop out, like the length contraction viewed by a photon?

 

[Eudaimonist]

Mathematics is just a way of modelling the universe. I don't think that the nature of the universe forbids the existence of phenomena that can't be successfully modelled mathematically (such as involving a division by zero). Nature isn't mathematics itself, or at least not as far as I can tell. The view that nature is, in some sense, mathematics strikes me as an echo of Platonism.


eudaimonia,

Mark

 

[Jazer]

You have big rock vs little rock. Peter is the little rock. The Rock Jesus builds His Church on is the big Rock.

Jesus is the corner stone. The apostles are the foundation stones. All the other stones go on top of the foundation. In the temple the stones were already formed when they got there. There was no sound of a hammer or a chisel when they were building the temple.

1 Pet2 4And coming to Him as to a living stone which has been rejected by men, but is choice and precious in the sight of God, 5you also, as living stones, are being built up as a spiritual house for a holy priesthood, to offer up spiritual sacrifices acceptable to God through Jesus Christ.

Eph 2 having been built on the foundation of the apostles and prophets, Christ Jesus Himself being the corner stone, 21in whom the whole building, being fitted together, is growing into a holy temple in the Lord, 22in whom you also are being built together into a dwelling of God in the Spirit.

There would be no church if it were not for Peter, he is the one that was preaching on the day of Pentacost. Although maybe God could have found someone else to preach that day if Peter was found not to be worthy.

 

[Chalnoth]

Right: it says that things can be infinitely dense (such as what happens to matter in a black hole), but there are reasons to believe that it's wrong at these scales. I agree that GR is wrong when it says that there are actual infinities, but only because that conflicts with QM. But, I'm not convinced that it's impossible to have, say, infinitely dense matter. It may be impossible in practice due to various physical laws, but I don't see why it can't possibly happen. Surely we can model things in such a way that true infinities pop out, like the length contraction viewed by a photon?

But the point is that if you take the singularities seriously, and don't hide them in some fashion, then the theory can no longer make any predictions.

 

[Chalnoth]

.

 

[Wiccan_Child]

But the point is that if you take the singularities seriously, and don't hide them in some fashion, then the theory can no longer make any predictions.

You can't divide by zero, but you can have infinities. Density isn't a 'real' thing, so even though we define it as mass over volume, and thus mass distributed over zero volume has a meaningless density, that doesn't invalidate the concept of density, nor does it negate the possibility that a finite (or, indeed, infinite) amount of matter can't be distributed over zero volume. Just because density approaches infinity as volume approaches zero, doesn't mean volume can't be zero.

I prefer to think of science as descriptive, not prescriptive. If infinite densities can exist, we have to allow for them.

 

[Chalnoth]

You can't divide by zero, but you can have infinities.

The two are just different aspects of the same thing. You can't have actual infinities just like you can't have actual divisions by zero in a physical theory that accurately describes reality.

Density isn't a 'real' thing, so even though we define it as mass over volume, and thus mass distributed over zero volume has a meaningless density, that doesn't invalidate the concept of density, nor does it negate the possibility that a finite (or, indeed, infinite) amount of matter can't be distributed over zero volume. Just because density approaches infinity as volume approaches zero, doesn't mean volume can't be zero.

In General Relativity, the real problem is the space-time curvature (specifically, the Ricci scalar) becoming infinite. This causes the features of General Relativity to break down. For example, you know the rule where you can take any small region of space-time and transform it into coordinates with a locally-flat space-time? Well, you can't do that if there is a singularity in your small region.

I prefer to think of science as descriptive, not prescriptive. If infinite densities can exist, we have to allow for them.

The main point here is that the scientific theories which we have are all approximations to the behavior of reality. We have no true theory, they all have problems. For example, in quantum field theory, if you start adding Feynman diagrams beyond about 150th order or so (I forget the exact order, but it's around there), then the new terms in the expansion start to diverge. This is a strong indication that there is something fundamentally incorrect about the Feynman diagram prescription. It might be, for example, that particles are treated as point-like in this description.

So we always have to be careful to not take our theories too seriously in all cases. It's important to have a good feel for where they are valid, and where they are not. And the mathematical difficulties of true singularities are, I'm pretty sure, completely incompatible with reality, because reality must be self-consistent, and singularities simply aren't consistent (you recover consistency in a theory with singularities by hiding the singularities, e.g. by cutting them out of the manifold in GR).

 

[mzungu]

Is movement in spacetime at the planck level stepped or is it uniform?

If it is stepped then this leaves room for chaos to reign supreme within the interval boundaries. But as I suspect; since we are talking at the planck level then chaos is the order of the day anyway!

Also As I suspect that if the Multiverse theory were proven; Will this mean that each universe will have its own creator and thus God is not alone? Just kidding on this one but imagine if it were proven that there are infinite universes, then God's role becomes the more lesser by each new big bang!

 

[Wiccan_Child]

The two are just different aspects of the same thing. You can't have actual infinities just like you can't have actual divisions by zero in a physical theory that accurately describes reality.

Why not? Infinitely large density that arises from a mathematical division by zero isn't a problem, since the only two real properties (mass and volume) remain real, well-defined quantities. If density is a concept that stops making sense in real situations, well, so much for density.

In General Relativity, the real problem is the space-time curvature (specifically, the Ricci scalar) becoming infinite. This causes the features of General Relativity to break down. For example, you know the rule where you can take any small region of space-time and transform it into coordinates with a locally-flat space-time? Well, you can't do that if there is a singularity in your small region.

Probably not, but that would surely be the fault of GR, not reality.

The main point here is that the scientific theories which we have are all approximations to the behavior of reality. We have no true theory, they all have problems. For example, in quantum field theory, if you start adding Feynman diagrams beyond about 150th order or so (I forget the exact order, but it's around there), then the new terms in the expansion start to diverge. This is a strong indication that there is something fundamentally incorrect about the Feynman diagram prescription. It might be, for example, that particles are treated as point-like in this description.

So we always have to be careful to not take our theories too seriously in all cases. It's important to have a good feel for where they are valid, and where they are not. And the mathematical difficulties of true singularities are, I'm pretty sure, completely incompatible with reality, because reality must be self-consistent, and singularities simply aren't consistent (you recover consistency in a theory with singularities by hiding the singularities, e.g. by cutting them out of the manifold in GR).

Then the problem with singularities lies in how we model them with GR or the like. Really will obey whatever GUT it ultimately follows, and if that set of laws allows for matter to be infinitely dense, we have to be open to theories that also allow for this. If gravity really does increase without limit, such as in black holes, then we'll get singularities. But I don't see why they can't exist in reality.

 

[Chalnoth]

Probably not, but that would surely be the fault of GR, not reality.

That's my point.

Then the problem with singularities lies in how we model them with GR or the like. Really will obey whatever GUT it ultimately follows, and if that set of laws allows for matter to be infinitely dense, we have to be open to theories that also allow for this. If gravity really does increase without limit, such as in black holes, then we'll get singularities. But I don't see why they can't exist in reality.

Reality can't be nonsensical. Singularities are nonsensical. There's no way something nonsensical can exist.

 

[Wiccan_Child]

That's my point.


Reality can't be nonsensical. Singularities are nonsensical. There's no way something nonsensical can exist.

Well, maybe they're not nonsensical