Can randomness exist?

[Rusty_the_boy_robot]

I'm trying to work through a problem and was hoping to get some feedback and ideas from people here. This is just for my own personal satisfaction and not for any type of publication, at all.

The question is, can anything truly be random?

Let us first define random as:

Not caused.

Now let us define caused as:

"It" is caused if a prior state necessitated "it's" occurance.

So what is your take on this? Is it possible for something to occur that was not necessitated by a prior state?

I've tried reading up on quantum physics and am slowly making progress (slowly being a key word), but I don't know what the 'official' take on this would be. I know that physics does not allow random occurances, but does quantum physics? I have the sneaking suspicion that I am not understanding what I am reading, or am misinterpreting it...

Bell's Theorom suggests one of several things, could one of the things be that the state of the particles are not necessitated by the prior state? This doesn't mean not influenced, simply not necessitated? Thus making these particles act in a random fashion?

Thanks,

 

[Stimpson J. Cat]

Rusty,

I'm trying to work through a problem and was hoping to get some feedback and ideas from people here. This is just for my own personal satisfaction and not for any type of publication, at all.

The question is, can anything truly be random?

Let us first define random as:

quote:
--------------------------------------------------------------------------------
Not caused.
--------------------------------------------------------------------------------

Now let us define caused as:

quote:
--------------------------------------------------------------------------------
"It" is caused if a prior state necessitated "it's" occurance.
--------------------------------------------------------------------------------

So what is your take on this? Is it possible for something to occur that was not necessitated by a prior state?

Not only is it possible, we have very strong scientific evidence that this happens all the time. I would be very careful with your definitions, though. Specifically, "causal" as you have defined it does not exhaust all possible forms of determinism.

I will try to give you an example of what I mean. Let's imagine you have a system governed by the following rules:

X(t) = f(X(t-a)),

where f is some mathematical function, and t is time.

Now this fits your definition of caused. Specifically, the state of X at any time is necessitated by its state at a prior time.

But consider this system:

X(t) = f(X(t-a), X(t+a))

In this case, the state of X at any time depends on its state at a prior time, and a future time. This example is still deterministic, but it is not causal.

I've tried reading up on quantum physics and am slowly making progress (slowly being a key word), but I don't know what the 'official' take on this would be. I know that physics does not allow random occurances, but does quantum physics?

I can only assume when you say that physics does not allow random occurrences, you are referring to classical mechanics. We now know that classical mechanics is only an approximation, which is very accurate under some conditions, but not strictly speaking a valid description of Nature.

Quantum Physics is acausal, which is to say that Quantum theory is not consistent with the hypothesis that quantum events are causal. Quantum theory is consistent with the hypothesis that quantum events are deterministic, but it does not require this. The mathematical theory itself models quantum events as being random, but does not strictly require that they be random, as long as they are acausal.

In other words, Quantum theory is non-deterministic, but reality may not be. We have stuck with the non-deterministic model so far, not out of any preference for non-determinism, but simply because the non-deterministic model we have right now it the most parsimonious explanation for the data we have at this time.

I have the sneaking suspicion that I am not understanding what I am reading, or am misinterpreting it...[/quote]

It is best to start simple. Quantum mechanics is not simple. One recommendation I can make is to do an internet search on digital filters. Once you mathematically understand the difference between a causal and acausal filter, what I am saying here will probably make more sense. And filters are a much simpler concept for trying to get the idea across then jumping straight into something as complex and counter-intuitive as QM.

Bell's Theorom suggests one of several things, could one of the things be that the state of the particles are not necessitated by the prior state? This doesn't mean not influenced, simply not necessitated?

That is exactly what it states.

Thus making these particles act in a random fashion?

They certainly appear to be random, but it is possible that they behave in a deterministic, but acausal, way. We don't know. It is, in principle, possible to falsify the hypothesis that they are random (meaning non-deterministic), but it is not possible to falsify that they are deterministic. This means that until such time as they are demonstrated to be deterministic, we must assume that they are not.

Dr. Stupid

 

[Rusty_the_boy_robot]

Thanks for the response, I'll go search for digital filters now.

That (definition of determinism)certainly makes sense though. I suppose I made a fallacious assumption when reading the definition of determinism. Two distinct moments of time certainly does not mean time in the "past". Thanks again.

But where would you get the idea that future states could necessitate present or past states? Is this possibility somehow suggested by QP?

I'll be back

 

[Rusty_the_boy_robot]

Hmm, well the search for digital filters is giving results that are far beyond my accounting math skillz

Perhaps you could recommend a book or more generalized subject that I could get a book about? I have the time, that's for sure!

 

[Interesting Ian]

Rusty
I'm trying to work through a problem and was hoping to get some feedback and ideas from people here. This is just for my own personal satisfaction and not for any type of publication, at all.

The question is, can anything truly be random?

Let us first define random as:



quote:
--------------------------------------------------------------------------------
Not caused.
--------------------------------------------------------------------------------

Either physically or mentally.

Now let us define caused as:


quote:
--------------------------------------------------------------------------------
"It" is caused if a prior state necessitated "it's" occurance.
--------------------------------------------------------------------------------

No, I think QM implies there is inherent randomness in all physical events, although this is not noticable on the macroscopic scale. And I think it is wrong to think that events that are caused are necessitated. When we say that A causes B we simply mean that whenever A occurs B will occur. But there is nothing inherently absurd about B not occuring given A. It's just the way the world is.

 

[Interesting Ian]

Rusty,



Not only is it possible, we have very strong scientific evidence that this happens all the time. I would be very careful with your definitions, though. Specifically, "causal" as you have defined it does not exhaust all possible forms of determinism.

I will try to give you an example of what I mean. Let's imagine you have a system governed by the following rules:

X(t) = f(X(t-a)),

where f is some mathematical function, and t is time.

Now this fits your definition of caused. Specifically, the state of X at any time is necessitated by its state at a prior time.

But consider this system:

X(t) = f(X(t-a), X(t+a))

In this case, the state of X at any time depends on its state at a prior time, and a future time. This example is still deterministic, but it is not causal.

Why isn't it? And what do these equations mean??

 

[Interesting Ian]

Quantum Physics is acausal, which is to say that Quantum theory is not consistent with the hypothesis that quantum events are causal. Quantum theory is consistent with the hypothesis that quantum events are deterministic, but it does not require this. The mathematical theory itself models quantum events as being random, but does not strictly require that they be random, as long as they are acausal.

Perhaps you could be good enough to name an acausal event which isn't random.

 

[Vorticity]

------------------------------------------------------------
But consider this system:

X(t) = f(X(t-a), X(t+a))

In this case, the state of X at any time depends on its state at a prior time, and a future time. This example is still deterministic, but it is not causal.
-------------------------------------------------------------
Why isn't it? And what do these equations mean??

It's not causal because the value of X at time t depends not only on the value of X at time t-a, which is in the past, but also on the value of X at time t+a, which is in the future.

Things whose behaviour now depends on what happens in the future are not causal.

t is time. a is a positive constant. X is some number that is varying with time t. f is a function that you plug two numbers (i.e. X at time t-a and X at time t+a) into to get a third number (i.e. X at time t).

These equations are still deterministic because (for some choices of the function f) there exists at least one function X of time that satisfies the equation.

 

[Stimpson J. Cat]

Rusty,

But where would you get the idea that future states could necessitate present or past states?

It has been suggested by many people as a possible way for determinism to be valid in QM. I personally do not believe this is the case.

Is this possibility somehow suggested by QP?

Not really. But what QM does tell us is that if these events are deterministic, then they are not determined solely by past events.

This is what is meant when people talk about non-local hidden variables. Because of the way relativity works, any phenomenon which is non-local cannot be causal.

Hmm, well the search for digital filters is giving results that are far beyond my accounting math skillz

Perhaps you could recommend a book or more generalized subject that I could get a book about? I have the time, that's for sure!

I'll see what I can find. The books I use as references are not suitable for an introduction to the subject. What is your mathematical background?


Ian,

Why isn't it? And what do these equations mean??

It is not causal, because the state of X at time t is determined by both the state of X at time t-a, and at time t+a. This means that the state of X at time t is not necessitated by its state at prior times. That is what the equations mean.

Perhaps you could be good enough to name an acausal event which isn't random.

Nope, sorry. I don't know of any. I know of a lot of acausal events which could be random, or they could be acausally deterministic. I don't know which they are. All I know is that either description is consistent with the available evidence. Scientists often refer to such event as being random, but this is just because our model for describing these events (QM) is non-deterministic. That model may not be correct (indeed, we can be pretty certain that it is not). The correct model may or may not be deterministic. All we really know is that our current model is the simplest model available that accurately describes the available data.

Dr. Stupid

 

[tamiO]

The question is, can anything truly be random?

Well, that is certainly a random question !

 

[Rusty_the_boy_robot]

My math background was better, long ago. I finished calculus studies <10 years ago and only use algebra day-to-day.

Perhaps I should just stick to "Physics for Dummies" or something

There are some interesting "layman's" descriptions of QP though.

Several pages are referencing an experiment where one photon is passed through a slit with another slit next to it and somehow the photon passes through both slits or something? Argh. I don't get it

How can one particle pass through two slits simultaneously? I must be reading something wrong here.

 

[Rusty_the_boy_robot]

So the theory of relativity states that c is the fastest any particle can move, hence anything that appears to be moving faster has actually traveled backwards through time?

You know I should find a better forum for this stuff.

 

[Yahzi]

The particle/slit expierment works like this:

Light is made up of photons, which are particles: and obviously, a particle can only go through one slot. So you fire a single photon, and it goes through one of two target slots. Your photon gun isn't very accurate, so its a randon chance which slot it passes through. You fire another one, and so on, and so on. Each time you fire, the photons have to go through one slot or another. You can record them one at a time, and that is in fact what they do.

Light is made up of a wave: imagine sticking a wall with two slots into a pool of water, and then dropping a pebble in the water. The pebble causes a wave, and when the wave hits the wall, two smaller waves come out through the slots. These waves then interfere with each other (drop two pebbles into the water a few feet apart and watch what happens when the waves hit each other - that's interference). Light does the same thing: if the slots are small enough, when you shine a beam of ligth through the two slots, they create an interference pattern on the other side.

Now here's the deal: both the above paragraphs are true. When you fire photons randomly one at a time through the slots, they go through random slots. But after you've fired enough photons, you notice that an interference pattern has built up on the other side of the slots - just as if you had fired all the photons at the same time.



Ain't physics wacky?

 

[Interesting Ian]

It's not causal because the value of X at time t depends not only on the value of X at time t-a, which is in the past, but also on the value of X at time t+a, which is in the future.

Things whose behaviour now depends on what happens in the future are not causal.

Why not? Causality is arbitrarily defined that way? Can you name any example of things whose behaviour is influenced by what will happen in the future? Hmmmm, I suppose our behaviour might be influenced by a precognitive dream of an unpleasant event

 

[Interesting Ian]

The particle/slit expierment works like this:

Light is made up of photons, which are particles: and obviously, a particle can only go through one slot. So you fire a single photon, and it goes through one of two target slots. Your photon gun isn't very accurate, so its a randon chance which slot it passes through. You fire another one, and so on, and so on. Each time you fire, the photons have to go through one slot or another. You can record them one at a time, and that is in fact what they do.

Light is made up of a wave: imagine sticking a wall with two slots into a pool of water, and then dropping a pebble in the water. The pebble causes a wave, and when the wave hits the wall, two smaller waves come out through the slots. These waves then interfere with each other (drop two pebbles into the water a few feet apart and watch what happens when the waves hit each other - that's interference). Light does the same thing: if the slots are small enough, when you shine a beam of ligth through the two slots, they create an interference pattern on the other side.

Now here's the deal: both the above paragraphs are true. When you fire photons randomly one at a time through the slots, they go through random slots. But after you've fired enough photons, you notice that an interference pattern has built up on the other side of the slots - just as if you had fired all the photons at the same time.



Ain't physics wacky?

No, not at all. What's so surprising about what you've outlined?

 

[Stimpson J. Cat]

Ian,

Why not? Causality is arbitrarily defined that way?

Yes. All definitions are arbitrary. Those examples were posted in response to Rusty's question, in which he gave a definition of the word, and the examples are phrased in terms of the definitions he gave. That is also the definition used for the word in science. If you want to come up with a different arbitrary definition, by all means feel free. But such a definitions has nothing to do with what is being discussed here.

Can you name any example of things whose behavior is influenced by what will happen in the future? Hmmmm, I suppose our behavior might be influenced by a precognitive dream of an unpleasant event

Maybe. I'll tell you what. If you can come up with a logical reason to believe this might actually be the case, and construct a falsifiable hypothesis for how it happens, let me know.

There is no reason to believe that such acausal deterministic phenomena exist in nature. We just do not know for sure that they do not.

Dr. Stupid

 

[Rusty_the_boy_robot]

The particle/slit expierment works like this:

Light is made up of photons, which are particles: and obviously, a particle can only go through one slot. So you fire a single photon, and it goes through one of two target slots. Your photon gun isn't very accurate, so its a randon chance which slot it passes through. You fire another one, and so on, and so on. Each time you fire, the photons have to go through one slot or another. You can record them one at a time, and that is in fact what they do.

Light is made up of a wave: imagine sticking a wall with two slots into a pool of water, and then dropping a pebble in the water. The pebble causes a wave, and when the wave hits the wall, two smaller waves come out through the slots. These waves then interfere with each other (drop two pebbles into the water a few feet apart and watch what happens when the waves hit each other - that's interference). Light does the same thing: if the slots are small enough, when you shine a beam of ligth through the two slots, they create an interference pattern on the other side.

Now here's the deal: both the above paragraphs are true. When you fire photons randomly one at a time through the slots, they go through random slots. But after you've fired enough photons, you notice that an interference pattern has built up on the other side of the slots - just as if you had fired all the photons at the same time.



Ain't physics wacky?

Thanks for the answer, but I have more questions....

What is an interference pattern?

Also you are asserting that the gun is not accurate enough for us to predict which slit the particle will pass through. This is different from asserting that it us random under the definition I gave. Which means we are most likely using different defintions.

So, if I remember correctly, the wavelength of light is known. So where would the randomness be occuring? Are these experimenters unable to predict at what point the wave will begin? Or is it that the measurements are so miniscule that we do not have the instruments for accurate measurement?

What I mean is, where is the randomness?

O yeah, and what is an interference pattern?

Thanks for your patience and answering my Q's!

 

[Interesting Ian]

Can you name any example of things whose behavior is influenced by what will happen in the future? Hmmmm, I suppose our behavior might be influenced by a precognitive dream of an unpleasant event
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Maybe. I'll tell you what. If you can come up with a logical reason to believe this might actually be the case, and construct a falsifiable hypothesis for how it happens, let me know.

If we can dream about past events then why is it inherently absurd to dream about future events? What distinguishes the future from the past?

Falsify that I've just been to my local shop (store?) to buy a Sunday Times. What you can't?? Can't have happened then! Such is the stupidity of Skeptical "reasoning".

 

[Dub]

If we can dream about past events then why is it inherently absurd to dream about future events? What distinguishes the future from the past?

Falsify that I've just been to my local shop (store?) to buy a Sunday Times. What you can't?? Can't have happened then! Such is the stupidity of Skeptical "reasoning".

Past events have already happened, future events havent; simple.

It would be possible to falsify whther you have been to your local shop to buy the Time if someone really wanted to and had the time and resources. Would just take simple detective work. How do you think crimes are ever solved?

 

[Rusty_the_boy_robot]

If we can dream about past events then why is it inherently absurd to dream about future events? What distinguishes the future from the past?

That's a good question. I haven't given that much thought. Perhaps you could start a new thread and give me some ideas?

Falsify that I've just been to my local shop (store?) to buy a Sunday Times. What you can't?? Can't have happened then! Such is the stupidity of Skeptical "reasoning".

I would have to disagree here, though. But I'd rather not disagree in the random thread.


But I still wonder if Stimpson or any other physicalist/materialist would agree that random things happen. I didn't see a direct answer in any of the above.