Ship of Fools: Quantum uncertainty

Thread: Quantum uncertainty Board: Oblivion / Ship of Fools.

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Posted by Lilac (# 17979) on :

Does anybody here know about Quantum Theory and the "uncertainty principle"? Does it imply that God plays dice with the world, as Einstein feared?

Posted by TheAlethiophile (# 16870) on :

I know a little about it. I did a 3rd year module in quantum mechanics and a 4th year module in advanced quantum theory as part of my MMath degree. Though that was nearly a decade ago now.

The basic statement of Heisenberg's uncertainty principle is that the commutation relation between position and momentum is non-zero. The consequence of this is that the more precisely one measures position, the less certainty one can have over a particles momentum.

This implies that the act of observing a quantum state changes it. In loose mathematical terms, the waveform collapses and an eigenvalue drops out, that being the quantity observed.

For more philosophical/theological implications, you could do worse than read some of the works of John Polkinghorne, a well respected particle physicist who is also an anglican priest.

Posted by pimple (# 10635) on :

Being totally immune to maths, all my sympathies are with the eigenvalue.

Posted by Alan Cresswell (# 31) on :

I should know a little about quantum mechanics, after all my PhD studied many-body quantum systems (aka Nuclear Physics).

As TheAlethiophile has said, the Uncertainty Principle is a consequence of the mathematics of wavefunctions.

At a quantum level particles (eg: electrons) can be described as waves, and waves (eg: light) can be described as particles (in the case of light, these are called photons). Physicists tend to use whichever description makes the maths easier - so, if you have a laser passing through a diffraction grating you use a wave model, but if that beam then hits a surface liberating electrons (the photoelectric effect) then suddenly we switch to talking about particles. The maths are basically unchanged if you swap a laser beam for an electron beam.

How the wavefunction works, in a hand waving kind of way, is that a wave of a single frequency has no spatial information at all, it just keeps oscillating up and down the same way in all directions to infinity. Frequency relates to energy and hence momentum. If you start adding together waves of different frequencies you create packets of probability, adding spatial information, but then you loose the well defined frequency (=energy/momentum). You can never know both energy/momentum and position precisely.

Does that mean God play dice? Einstein, of course, was not making a theological point at all, he was merely expressing his views that physics should ultimately be deterministic, and have no element of probability involved at all. Which on a large scale seems to be the case. Radioactive decay is governed by quantum physics, and is random - we can never know when a given nucleus will decay. But, given enough radionuclides in a sample we can say with very high precision how many of them will decay in a given time. Gas molecules in a bottle move and interact by quantum processes - we can never say precisely where and how fast any given molecule is moving. But, given enough molecules in a jar we can say with high precision how the pressure will vary as we heat up the jar.

Einstein thought that quantum processes only appear to be indeterminate, but that there is some underlying physics that is entirely determinate. If we could understand that deeper physics then what appears to be indeterminate would turn out to be determinable. Such ideas get called "hidden variable" interpretations, because there is some variable we can't see that makes a determinate physics indeterminate.

The theological question really asks how we view the interaction of God with the physical universe. Is God absolutely in control of absolutely everything, even determining when a radionuclide decays? Or is he more stand-back, letting things proceed independently of his direct causation?

Posted by Crœsos (# 238) on :

quote:
Originally posted by Alan Cresswell:
Does that mean God play dice? Einstein, of course, was not making a theological point at all, he was merely expressing his views that physics should ultimately be deterministic, and have no element of probability involved at all.

A good rule of thumb for this sort of thing is that the more abstract an application a physicist is discussing the less likely their use of "God" as an analogy/reference/metaphor will resemble the personal Judeo-Christian deity.

Given how "indeterminate" a concept God is (see what I did there?), I wish scientists in general and physicists in particular would find a different term to use when they're feeling grandiose.

Posted by quetzalcoatl (# 16740) on :

It doesn't imply anything at all about God, does it? Scientific theories have no connection with theism, at all, since they are explicitly naturalistic systems.

I suppose if you want, you can attempt to make some speculations about God, kind of in parallel to the scientific ideas, but basically, you are guessing. Well, you can't beat a good guess, I say.

Posted by TheAlethiophile (# 16870) on :

quote:
Originally posted by quetzalcoatl:
It doesn't imply anything at all about God, does it? Scientific theories have no connection with theism, at all, since they are explicitly naturalistic systems.

I suppose if you want, you can attempt to make some speculations about God, kind of in parallel to the scientific ideas, but basically, you are guessing. Well, you can't beat a good guess, I say.

It depends on your starting point. What you say sounds similar to the non-overlapping magisteria (NOMA) view of, say, Stephen Jay-Gould.

That would differ from a natural theology, most recently advocated by the likes of Alister McGrath, rather than a Paley-esque view which runs up against a Hume-shaped brick wall.

An example of how QM may inform would be if we were adopt the many-worlds interpretation and then ask questions such as "is there a universe in which Jesus was stillborn?" - it may seem like the same category of "how many angels can dance on the head of a pin", but it makes one think.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

Does God know if it's going to rain tomorrow?

Posted by quetzalcoatl (# 16740) on :

Many worlds theory has been used in the argument, that if God is possible, then in a many-worlds universe, God must exist. This is a bit like the possibly necessary argument, which I think some philosophers have been interested in. Personally, this stuff leaves me cold. It's possible that we live in a matrix, engineered by a bored adolescent octopus living on a distant planet.

[ 03. February 2014, 16:17: Message edited by: quetzalcoatl ]

Posted by IngoB (# 8700) on :

quote:
Originally posted by Lilac:
Does anybody here know about Quantum Theory and the "uncertainty principle"? Does it imply that God plays dice with the world, as Einstein feared?

I do know a bit, from a previous life including a PhD... If I may be so bold to link to an old post of mine addressing this topic: A random proof of God.

Posted by Adeodatus (# 4992) on :

quote:
Originally posted by Martin PC not & Ship's Biohazard:
Does God know if it's going to rain tomorrow?

No. God knows it's raining tomorrow. Or he knows it's not raining tomorrow. There's no "going to" with God.

There's quite a good normal-world analogy for the uncertainty principle. Suppose you were given a camera and told to use it to measure the speed and position of a passing car. Simple, you think. I set the shutter speed to 1 second and point it at the car. From the blur on the photo I can work out how far the car travelled in 1 second, and thus work out its speed.

But oh dear. The car's a blur, so although I know its speed I can't really point to where it "is".

So I try again. I set the shutter speed to 1/1000 second and try again. This time there's a crisp, clear image of the passing car, so I can tell its position precisely. But because the image is so pinpoint-clear, there's no blur from which I can work out the car's speed.

So it turns out I can know the car's speed, or its position, but not both at the same time. If you translate that to a quantum level with the appropriate mathematical jiggery-pokery, it's Heisenberg's uncertainty principle.

Posted by no prophet (# 15560) on :

I tend to shy away from our metaphors for the natural world being applied to ultimate questions. Quantum theory I think is merely our way of describing what we observe. Thus, God seeming to play dice or being involved or doing a hands-off with the world is merely our construction of things as much as our meagre minds can manage,

I recall reading a novel by Robertson Davies, Murther and Wandering Spirits, where the main character is killed within the first paragraph and then is shown movies of his ancestors from some 200 years earlier. The seeming dice playing from that 200 years earlier was being realized in the present day of the novel. Which points to both a perceptual and modelling with our minds problem, as well as forgotten or never recorded details. Thus, the appearance of this uncertainty.

Posted by Schroedinger's cat (# 64) on :

quote:
Originally posted by Lilac:
Does anybody here know about Quantum Theory and the "uncertainty principle"? Does it imply that God plays dice with the world, as Einstein feared?

Does God play dice? No. However, the concern that Einstein had, that the world may not be deterministic, is valid.

What has changed is that the mathematics used to understand probabilistic outcomes has advanced, and we now appreciate that non-deteministic at the quantum level does not mean the same at a macro level. So we can still rely on determinism for most of our practical life, but probabilistic techniques are the best ones to use to understand the working of the universe at a quantum level.

The theological questions are whether the universe needs to be deterministic to sustain a belief in an interactive God - a position that I do not accept. In fact, I think a proper understanding of quantum theory, at least as much as a lay-person such as me can understand, is totally compatible with a belief in a Christian God.

Posted by Patdys (# 9397) on :

Thank you for the car analogy. That is rather elegant.

Posted by que sais-je (# 17185) on :

quote:
Originally posted by Crœsos:
Given how "indeterminate" a concept God is (see what I did there?), I wish scientists in general and physicists in particular would find a different term to use when they're feeling grandiose.

A bit unfair to Einstein. His references to "the Old One" are frequent enough (see InGoB's proof for an example) to suggest a belief (of sorts) in a Spinozan sort of Deity in everything.

Shipmates regular impute all sorts of things to God that some of us wouldn't but I see no reason why they shouldn't. And if they were as clever as Einstein (I'm sure some are) I would be even more attentive to their thoughts.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

So all of the future has already happened? WOWWWWW! Entity proliferation or what! God sure is one BIG clock.

Posted by quetzalcoatl (# 16740) on :

The idea that interests me is that there is no future. In one way, it seems really obvious, since if there is, where the fuck is it? In the mind of God, I suppose.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

Nope. There is no such thing. God can be as timelessly now as He likes, our past is dead and our future is null.

Posted by Lilac (# 17979) on :

Hmm, I didn't understand most of that. But I know a website, "libgen", full of useful books, and I downloaded a bunch of John Polkinghorne's on Quantum Theory. Let's see how I get on.

But I thought the problem with the Uncertainty Principle was that originally people like Newton believed deterministic "laws of nature" were evidence of intelligent design, presumably by God.

Posted by Pulsator Organorum Ineptus (# 2515) on :

The car analogy doesn't really work because it is about uncertainty in making measurements.

Quantum uncertainty is quite different. Quantum uncertainty says that you can't predict accurately, not that you can't measure accurately.

In terms of the car, it goes more like this. You have an incredibly accurate camera that will measure the position passing cars, and an incredibly accurate radar gun that will measure their speed.

Up the road there's some gizmo that releases identical cars occasionally - round about once every ten minutes, say.

When a car passes, you EITHER measure its position with the camera, OR its speed with the radar gun.

When you plot the positions, you find that, although you have measured them to the micron, they are spread out over several metres. And although you have measured the speeds to the nearest 1/1000 mph, they are spread out over tens of mph.

The uncertainty principle tells you that the spread of speeds multiplied by the spread of positions can't be less than ... well, some value given by a formula involving the mass of the cars.

Posted by David (# 3) on :

quote:
Originally posted by Schroedinger's cat:
Does God play dice? No. However, the concern that Einstein had, that the world may not be deterministic, is valid.

Shouldn't you be dead by now?

Posted by mousethief (# 953) on :

quote:
Originally posted by Adeodatus:

quote:
Originally posted by Martin PC not & Ship's Biohazard:
Does God know if it's going to rain tomorrow?
No. God knows it's raining tomorrow. Or he knows it's not raining tomorrow. There's no "going to" with God.

Well said.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

Absolutely. Well said meaningless, incoherent rhetoric. God CANNOT have the faintest idea whether it's going to rain tomorrow by looking at it. He can't look at what is null, what isn't. What hasn't happened.

Or He woodn't be God.

Posted by Alan Cresswell (# 31) on :

quote:
Originally posted by Lilac:
But I thought the problem with the Uncertainty Principle was that originally people like Newton believed deterministic "laws of nature" were evidence of intelligent design, presumably by God.

That might have been the view of Newton, it certainly was the view of many Christians. It's certainly true that quantum indeterminacy was one of the things that effectively killed off the concept of a divine watchmaker. Which, IMO, is no bad thing because there are enormous problems with that view of God regardless of whether quantum systems are fundamentally indeterminate.

Posted by Dafyd (# 5549) on :

quote:
Originally posted by Martin PC not & Ship's Biohazard:
Nope. There is no such thing. God can be as timelessly now as He likes, our past is dead and our future is null.

That can't be consistent.

We have no reason to think Einstein's theories aren't true here. According to Einstein's theories, my past is everywhere from where a ray of light could have got to me if there weren't anything in the way. So there's a four dimensional cone that gets wider as it gets further behind me in time. And my future is everywhere that a ray of light from me could reach: a four dimensional cone spreading out ahead of me in time.
And what about all the places and times in between those two cones? They're neither my future nor my past. They're all my present.
But... obviously some of those times are future and past to each other.
So, according to Einstein's theories, there's no such thing as the present. If you take five people none of whom are in each other's past or future, any given event might in the present of some of them, the past of others, and the future of yet others - even though all of those people are in each other's present.

That means that the future must be as real as the present or the past. Because there's no such thing as THE present: there's only my present and your present and Alice's present and Bob's present, and they're each of them subtly different.

Posted by Alan Cresswell (# 31) on :

quote:
Originally posted by Pulsator Organorum Ineptus:
Quantum uncertainty is quite different. Quantum uncertainty says that you can't predict accurately, not that you can't measure accurately.

Measurement and prediction are intrinsically linked. If you want to predict the future position of a particle then you need to know the current position and speed, and all forces that will act on it between now and then. For a quantum system there is a limit to how well you can know both the current position and speed, which directly relate to how well you can predict the future - or, if you have control over the forces act, how well you can control the future. And, it's nothing to do with instrumental uncertainty. Instruments capable of measuring speed and position to infinite precision (not that we can make these) would still face the same uncertainty.

Posted by Alan Cresswell (# 31) on :

Dafyd,

The problem is that there is no grand unified theory that links "classical" physics (which includes General Relativity) and quantum physics. So, classically you are right that there is no "now" in a physically meaningful sense. But, QM says that even "now" is indeterminate, and so extrapolation from "now" to "future" carries that indeterminacy with it. Non-linear dynamics inflates those uncertainties as you extrapolate into the "future".

So, the question isn't whether time exists. But one of how well any being (even one with infinitely precise measurement capability) can extrapolate from conditions at one place to another (whether that variation in position occurs through spatial or temporal dimensions)

Posted by Schroedinger's cat (# 64) on :

quote:
Originally posted by David:

quote:
Originally posted by Schroedinger's cat:
Does God play dice? No. However, the concern that Einstein had, that the world may not be deterministic, is valid.

Shouldn't you be dead by now?

Well, I am the macro demonstration of the quantum uncertainty. The point being that before observation I am BOTH alive AND dead - something that logical and deterministic minds struggle with. This is the God playing dice issue.

The thing is, once the box is opened - once an observation is made - the system becomes historically deterministic. That is, deterministic approaches can then be used to understand what had appeared to have happened.

It is the collapse of the probability functions that means the quantum uncertainty can exist within a deterministic macro world. However it does raise far more interesting questions - IMO - about the nature of reality, that Einstein couldn't even touch on.

The most critical, coming from my experiment, is that our observation does, in fact, change the state of reality, and it changes it historically. This has been demonstrated in real (quantum) situations recently, I believe. So if a tree falls in a forest and nobody sees it, then it has both fallen and not fallen.

Posted by Nicodemia (# 4756) on :

So with an Uncertainty Principle for the Physicists, and no past, present or future with God, and my present being different from your present, even if you could measure/define it, it doesn't matter that I am totally confused as to where God, if he exists, comes into all this??

[Confused]

Posted by Alan Cresswell (# 31) on :

One good question is, does God come into it at all? Quantum Mechanics is a description of the way the universe works at atomic and subatomic levels. Or, maybe how it appears to work if you prefer a hidden variable interpretation of the physics. The theory stands or falls irrespective of theology.

Of course, if you believe in a Creator then the nature of Creation must, in some manner, affect how you understand the Creator. And, that will also be reflected in how you see the Creator relating to the Creation - is the Creator totally transcendant and lets Creation run according to rules established at the beginning without interference, does the Creator tweak things as they progress, is the Creator intimately and immediately involved in every process within Creation?

Posted by quetzalcoatl (# 16740) on :

I don't see how anyone can know if or how God comes into it. You can of course guess, which is an honourable tradition. Or you can accept a particular existing tradition, which is probably based on guesswork.

For example, you might guess that a dragon belched flames, and out of these flames, emerged the world. Fair enough. Or you might guess that the Nigerian termite god shat out a turd, which turned out to be a universe. Also good. And so on and so on. I don't see that any particular version of theism is less of a guess than this.

Posted by que sais-je (# 17185) on :

quote:
Originally posted by Lilac:
Hmm, I didn't understand most of that. But I know a website, "libgen", full of useful books, and I downloaded a bunch of John Polkinghorne's on Quantum Theory.

I assume that's The Library Genesis Project. Website's in English and Russian with lots of stuff but no 'About' or other explanation. No signing up needed to download books.

They've got PDFs of an awful lot of books some of which I would have thought were copyright. Very Russian oriented, for example 'Religion' has subsections of Buddhism, Kabbalah, Orthodox Christianity, Spirituality and Mysticism. Which covers a lot of the old USSR except the obvious Elephant.

Does anyone know anything about it?

Posted by Martin PC not & Ship's Biohazard (# 368) on :

The Creator has no option.

Posted by Lilac (# 17979) on :

Yes it is the Library Genesis Project. They have all sorts of stuff. I downloaded a book on Accounting which I couldn't find elsewhere. Though it had crossed my mind that some books might be pirated. So I also got Roger Penrose's "The Road to Reality" but from my local library. I can't understand the maths, but I know a man who can.

John Polkinghorne says physicists are rejecting Reductionism, but they still see a significance when subatomic particles can be described by beautiful equations. Do you atomic physicists think this has implications for our everyday outlook? You didn't learn this stuff just to pass exams, surely?

Posted by Crœsos (# 238) on :

quote:
Originally posted by Alan Cresswell:
One good question is, does God come into it at all?

Maybe manipulating outcomes on a quantum level is how God smites the wicked. That seems to be a key part of His portfolio according to some believers.

quote:
Originally posted by Alan Cresswell:
Of course, if you believe in a Creator then the nature of Creation must, in some manner, affect how you understand the Creator. And, that will also be reflected in how you see the Creator relating to the Creation - is the Creator totally transcendant and lets Creation run according to rules established at the beginning without interference, does the Creator tweak things as they progress, is the Creator intimately and immediately involved in every process within Creation?

To work from the previous example, if you see God as being kind of "smitey", then He needs a mechanism by which He can get His smite on.

Posted by Schroedinger's cat (# 64) on :

quote:
Originally posted by Nicodemia:
So with an Uncertainty Principle for the Physicists, and no past, present or future with God, and my present being different from your present, even if you could measure/define it, it doesn't matter that I am totally confused as to where God, if he exists, comes into all this??

It does impact your understanding of reality, and so your understanding of God. And it can take a whole lot of time to get to grips with it.

As a simplistic starter, if nothing is definitive, all is probabalistic, then maybe God can - does - intervene in the probabilities that we observe. Maybe your particular perception of what counts for reality is modified and defined by Gods interaction with it.

Under a purely deterministic universe, of course, God cannot really intervene, because everything is already set in place. if nothing is set, determined, fixed, then is probably gives more scope for a divine being to be involved, without causing untold disruption.

Posted by Marvin the Martian (# 4360) on :

quote:
Originally posted by Dafyd:
We have no reason to think Einstein's theories aren't true here. According to Einstein's theories, my past is everywhere from where a ray of light could have got to me if there weren't anything in the way. So there's a four dimensional cone that gets wider as it gets further behind me in time. And my future is everywhere that a ray of light from me could reach: a four dimensional cone spreading out ahead of me in time.
And what about all the places and times in between those two cones? They're neither my future nor my past. They're all my present.

I'm with you right up to the last sentence. But surely anything outside the two "cones" is something you can never interact with in any way whatsoever, therefore is stuff that effectively does not exist for you. Your present is the tiny spot where the two cones meet, nothing more.

Posted by Doc Tor (# 9748) on :

quote:
Originally posted by Pulsator Organorum Ineptus:
The car analogy doesn't really work because it is about uncertainty in making measurements.

The problem in measuring is the size of the object you're measuring against the size of the object you're measuring with.

If all you had to measure how far/fast a car was moving was by driving other cars at it and seeing where the collisions were, it'd be pretty obvious that you're affecting where and how fast the car you're trying to measure is going.

Exactly the same problem exists, on the quantum scale for electrons. We fire electrons at electrons to see where the electrons are, because we have nothing smaller.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

Marvin the Martian via Dafyd or the other way around if one's coming at this from the future.

There's a ray of light leaving the sun now that will bounce off Jupiter and off me if I go outside in about 90 minutes.

Am I there looking up? Then now?

And as the ray bounces off me back to Jupiter and then to the sun in 3 hours what did I have for tea?

Posted by Dafyd (# 5549) on :

quote:
Originally posted by Marvin the Martian:

quote:
Originally posted by Dafyd:
And what about all the places and times in between those two cones? They're neither my future nor my past. They're all my present.
I'm with you right up to the last sentence. But surely anything outside the two "cones" is something you can never interact with in any way whatsoever, therefore is stuff that effectively does not exist for you. Your present is the tiny spot where the two cones meet, nothing more.

Some of it used to be my future and will be my past.
Either way, if any of it is real simultaneous with my present then all of it is. So, unless solipsism is true, realism about all such events is true. And if realism about all events outside my personal past and future holds, then it holds for events within my personal past and future as well.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

Ah, that explains it then.

Although, as you know, there is no such thing as absolute simultaneity.

Except in God's now of course.

Posted by Francophile (# 17838) on :

Its quite obvious to me that the squared ellipsis is reflecting electromagnetic particles from God's domain back to the helidomatic spectrum below the y axis of infinity.

Can anyone discuss?

Posted by Lilac (# 17979) on :

Long ago I read Eddington's "Nature of the Physical World". I've just downloaded it again. He actually makes this stuff look alot simpler. Has his book become outdated since 1929?

Posted by Pulsator Organorum Ineptus (# 2515) on :

quote:
Originally posted by Doc Tor:

quote:
Originally posted by Pulsator Organorum Ineptus:
The car analogy doesn't really work because it is about uncertainty in making measurements.
The problem in measuring is the size of the object you're measuring against the size of the object you're measuring with.

If all you had to measure how far/fast a car was moving was by driving other cars at it and seeing where the collisions were, it'd be pretty obvious that you're affecting where and how fast the car you're trying to measure is going.

Exactly the same problem exists, on the quantum scale for electrons. We fire electrons at electrons to see where the electrons are, because we have nothing smaller.

Perhaps I didn't explain myself well enough.

The uncertainty involved is not in the result of a single measurement: the uncertainty is in the randomness that occurs from measurement to measurement. Well at least that's how it was explained to me in lectures at Cambridge and how, for example, Penrose explains it.

It's as if we could determine the position of a car to (say) 10 yards, but from one measurement to the next, the positions varied by hundreds of kilometres in a completely unpredictable way, even though they were launched into the experiment from the same place (eigenvalue).

Posted by Schroedinger's cat (# 64) on :

I think Heisenbergs uncertainty was primary that you cannot identify all of the values of a quantum level item at once - that is, the speed and position are intricately related.

There has since been the development of chaos theory, which does relate to quantum level events too, in that there are activities that are not deterministic. So however we start events, we cannot determine their position and situation within a given time. The randomness (i.e. indeterminability) of quantum events makes them fundamentally chaotic.

What becomes more significant is that the act of measuring - or even observing - events changes them, meaning that we cannot be certain what would have happened if we had not intervened.

Posted by Marvin the Martian (# 4360) on :

quote:
Originally posted by Dafyd:

quote:
Originally posted by Marvin the Martian:
I'm with you right up to the last sentence. But surely anything outside the two "cones" is something you can never interact with in any way whatsoever, therefore is stuff that effectively does not exist for you. Your present is the tiny spot where the two cones meet, nothing more.
Some of it used to be my future and will be my past.

Can't be - if that was the case then it would be within the cones you described.

Posted by Dafyd (# 5549) on :

quote:
Originally posted by Marvin the Martian:

quote:
Originally posted by Dafyd:
Some of it used to be my future and will be my past.
Can't be - if that was the case then it would be within the cones you described.

This requires future imperfects and other complicated tenses. And I can't do diagrams with ASCII art.

Simplifying: imagine a 2D grid in which my subjective relativistic time on the t axis is plotted against relativistic distance from me on the d axis. I am at time t=0 d=0. Any event for which d is less than t and t >0 is in my future; any event for which -d>t and t is negative is in my past; any thing else is neither.
Now suppose an event at d 3, t 4. It's in my future. But when I'm at time t = 10, it will be in my past. And at time t= 5 it will be neither. That's what I meant.
(The point about relativism is that I can muck about with the absolute t and d values of any given event by altering the frame of reference. But I can't move events out of or into the cones at any given time.)

Posted by Eutychus (# 3081) on :

quote:
Originally posted by Dafyd:
This requires future imperfects and other complicated tenses.

As is well known, Dr Dan Streetmentioner is your friend in this respect [Smile]

Posted by Alan Cresswell (# 31) on :

quote:
Originally posted by Schroedinger's cat:
There has since been the development of chaos theory, which does relate to quantum level events too, in that there are activities that are not deterministic.

The interesting thing about non-linear dynamics (aka Chaos Theory) is that it applies to systems that can be described deterministically. A "simple" example would be planetary systems. The motion of each planet, moon, asteroid, comet, grain of dust, space probe can be described by General Relativity (and, except for locations very close to the Sun, Newtonian Mechanics are perfectly adequate). Those equations are all deterministic. A single planet orbiting a single star can be precisely modelled, and the orbit predicted to very high precision for a very long period of time from only a small number of observations of the position of the planet at different times. But, when you start introducing multiple planets, put moons in orbit around those planets, add an asteroid belt and a few comets ... the ability to predict the motion of any one of those bodies rapidly degrades.

Posted by Marvin the Martian (# 4360) on :

quote:
Originally posted by Dafyd:
Simplifying: imagine a 2D grid in which my subjective relativistic time on the t axis is plotted against relativistic distance from me on the d axis. I am at time t=0 d=0. Any event for which d is less than t and t >0 is in my future; any event for which -d>t and t is negative is in my past; any thing else is neither.
Now suppose an event at d 3, t 4. It's in my future. But when I'm at time t = 10, it will be in my past. And at time t= 5 it will be neither. That's what I meant.

I think I've got what you mean - an event that is within the "future" cone now will be in the "past" cone once time has gone past it. Assuming, of course, that your direction of travel within the cone takes you past it at all.

This stuff is easier with diagrams. I saw Brian Cox explain it really well once.

quote:
(The point about relativism is that I can muck about with the absolute t and d values of any given event by altering the frame of reference. But I can't move events out of or into the cones at any given time.)

Yes, that last bit was what I was talking about.

Posted by Martin PC not & Ship's Biohazard (# 368) on :

Nicodemia, all our nows are subjective. I can perceive events in your future now and the same for goes for you of mine. Perceive is the magic word.

All of material reality is thought by God. In one continuing delocalised instant. Singularity. All is reconciled in that. In Him. He doesn't have to wait for His thoughts to catch up with each other. From one unreachable end of the universe to the other.
This and this really do show what MtM and D are on about.

And says absolutely NOTHING about whether it's going to rain tomorrow. God is not standing on a hill looking down at all successive nows, all successive now lines, successive now horizons in ANY frame of reference. It hasn't rained or not tomorrow anywhere.

And no observer travelling near the speed of light for whom time dilates in our now can see then. Until now is then. Even though our now will take hours to become then and their now, which overlaps ours now, will become then in a few seconds.

Simultaneity is relative in the material, created, thought world.

Which, again, says NOTHING, proves, indicates absolutely NOTHING about the absolute future. The real future. The one that hasn't happened for anyone, anything. Including God.

God stands on His now hill just looking down at all our real single nows with their relative perceptions on the same, single horizontal now line where the unhappened future becomes the dead past.

Or He's Bender from Futurama with every frame of the movie of eternity spooled inside Him and He's looking at every frame eternally now.

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