True Random

[AbstractDreamer]

Not sure if this is in the right topic of Quantum Theory.

But what is the closest thing to true randomness?  As I understand, computer generated numbers are deterministic at the core; dice do not have even mass distribution; hidden variable theory suggests there is an underlying deterministic function to the probabilistic nature of the quantum world.

On the other hand, if there is no determinism in quantum probabilities, can true randomness be attained therein?

[studiot]

30 minutes ago, AbstractDreamer said:

Not sure if this is in the right topic of Quantum Theory.

But what is the closest thing to true randomness?  As I understand, computer generated numbers are deterministic at the core; dice do not have even mass distribution; hidden variable theory suggests there is an underlying deterministic function to the probabilistic nature of the quantum world.

On the other hand, if there is no determinism in quantum probabilities, can true randomness be attained therein?

To answer this one would need to know what exactly you mean by random (adjective) and randomness (noun) and probability.

Probability is a comparative measure, given by a number, of a particular result of a process, compared to other possible results.

Random is an adjective applied to that process itself, although we also bestow the title 'random result' on the result if it is deemed to have been generated by a random process.
So the Kolomgorov definition of a random number is one arrived at by the the explicit statement of the number as being the shortest process of generation.
 

[Strange]

5 hours ago, AbstractDreamer said:

Not sure if this is in the right topic of Quantum Theory.

But what is the closest thing to true randomness?  As I understand, computer generated numbers are deterministic at the core; dice do not have even mass distribution; hidden variable theory suggests there is an underlying deterministic function to the probabilistic nature of the quantum world.

On the other hand, if there is no determinism in quantum probabilities, can true randomness be attained therein?

There is the issue of defining randomness that studiot mentioned. For example, if your random number generator output the numbers 1 to 100 in sequence, you might think it wasn't being random enough and try to stop it doing that. But if you don't allow it to generate sequences like that (with the appropriate probability) then it isn't random!

Quantum processes are both random and deterministic: for example, we can predict what the result of atomic decay is but we can't say when a specific atom will decay. So radioactive decay is sometimes used for generating "truly random" numbers (think of the random clicks of a Geiger counter). Another common method in electronic circuits is to use the thermal noise generated in a resistor. Other sources described here: https://en.wikipedia.org/wiki/Hardware_random_number_generator

And if you want to generate some random numbers, there's an app (well, website) for that: https://www.random.org (Also has lots of good articles on randomness.)

(Hidden variable theories are ruled out by Bell's Theorem.)

[StringJunky]

10 minutes ago, Strange said:

There is the issue of defining randomness that studiot mentioned. For example, if your random number generator output the numbers 1 to 100 in sequence, you might think it wasn't being random enough and try to stop it doing that. But if you don't allow it to generate sequences like that (with the appropriate probability) then it isn't random!

Quantum processes are both random and deterministic: for example, we can predict what the result of atomic decay is but we can't say when a specific atom will decay. So radioactive decay is sometimes used for generating "truly random" numbers (think of the random clicks of a Geiger counter). Another common method in electronic circuits is to use the thermal noise generated in a resistor. Other sources described here: https://en.wikipedia.org/wiki/Hardware_random_number_generator

And if you want to generate some random numbers, there's an app (well, website) for that: https://www.random.org (Also has lots of good articles on randomness.)

(Hidden variable theories are ruled out by Bell's Theorem.)

Is a blindfolded/blind person pressing a button not random in the true sense?

[AbstractDreamer]

Ok, lets look at atomic decay.  I don't know, lets choose alpha decay.

We don't know when the nucleus will next produce an emission and decay, though statistically over time we can predict how much emission it will produce over time.   So we say the time of next emission is random but is that because of our limited knowledge and/or detection apparatus? 

@studiot If I wanted to choose 1 object at random from a set of objects, my definition of randomness is that nothing in the universe can predict which choice that would be.  That is my layman's definition.

Another query i have is how time plays a role in randomness.  

For example if an atomic nucleus decays at time t.  If we "rewound" time and passed through time t again, would that nucleus decay at exactly the same time?  If so, then it event was always deterministic, and not random, despite being seemingly random to us.

A truly random emission would be time independent.   Going back to my example of choosing 1 object at random.... then replaying that random choice process through time would produce either the same or a different result, but still unpredictable nevertherless.

PS. I thought bell theorem's only disproves local hidden variables?

 

Edited May 23, 2019 by AbstractDreamer

[Eise]

Just a few random thoughts...

I think one should distinguish between the result (e.g. a table of random numbers) and how the result was obtained. Say, I have two tables of random numbers, and a statistician analyses them, and concludes that both tables are truly random. Now these lists were created in totally different ways: one was created using 'truly random' quantum processes, the other a good pseudo-random computer algorithm that in itself is not dependent on other random processes (thermal noise, radio noise etc). So the pseudo-randomiser is deterministic, but the result indistinguishable by statistical analysis of the result. So in my opinion, there is no contradiction between a deterministic process and randomness, at least from a practical point of view. 

However, the importance of random numbers in e.g. cryptography is not the statistical distribution, but exactly this unpredictability of what the next number will be. A code-hacker shouldn't get a clue about what the next number will be, and a strictly mathematical algorithm does not suffice for that.

Contrast this with the following: I have a truly, unpredictable random number generator, but I write the results in a table. Now when I use this table in the order the numbers were generated, to pick the next random number does not change that they are truly random numbers. However, if the code-hacker somehow gets a copy of this list, we have the situation that the numbers are completely and perfectly random, but also perfectly predictable by the code-hacker.

And now to get to quantum physics again: we have the Bohm-interpretation of quantum mechanics that is strictly deterministic. However, Copenhagen- and Bohm-interpretation are empirically equivalent. How is that possible? I think it is exactly in this respect: in the Bohm-interpretation a quantum measurement depends on all particles in the universe, and so predictions are practically impossible. So even if quantum events would be deterministic, it does not help the code-hacker because he is not able to predict what the next number will be.

@koti: maybe we should distinguish between random1 and random2?

[Sensei]

15 hours ago, AbstractDreamer said:

As I understand, computer generated numbers are deterministic at the core;

 

1 hour ago, Eise said:

the other a good pseudo-random computer algorithm that in itself is not dependent on other random processes

Typical way C/C++ programmer is using the most basic C language built-in pseudo-random numbers generator is:

srand( time( NULL ) );
int value = rand();

to get value in range in 0....RAND_MAX (0x7fff = 32767)

Time is input parameter to so called random seed.

The same seed, the same sequence of numbers returned by rand() function.

But time (in seconds if returned by time() function) is changing, so each execution output sequence will be different. At least until overflow. srand() takes 32 bit unsigned integer as parameter, so overflow will happen after 2^32 / 60 / 60 / 24 / 365.25 = ~ 136 years (ignoring timezone changes)

Non-standard pseudo-random number generators typically use current time (better with millisecond/microsecond precision) of machine to initialize random seed (srand()-equivalent function parameter).

 

Edited May 23, 2019 by Sensei

[Strange]

6 hours ago, AbstractDreamer said:

For example if an atomic nucleus decays at time t.  If we "rewound" time and passed through time t again, would that nucleus decay at exactly the same time?  If so, then it event was always deterministic, and not random, despite being seemingly random to us.

As this is a non-physical question, it is hard to answer. However, as far as we know there is no "mechanism" that determines when the atom decays and so I would expect that it would be like taking another atom and watching it for the same time. 

To simplify this a bit, we can look at an unstable fundamental particle such as a muon. These will decay after about 2 microseconds. They are elementary particles so there is no mechanism counting down. They are all identical and so testing two different muons is the same as testing the same muon twice. The decay time is random.

[swansont]

7 hours ago, AbstractDreamer said:

 For example if an atomic nucleus decays at time t.  If we "rewound" time and passed through time t again, would that nucleus decay at exactly the same time?  If so, then it event was always deterministic, and not random, despite being seemingly random to us.

There's no way to test this.

[koti]

On 5/23/2019 at 8:28 AM, Eise said:

 

@koti: maybe we should distinguish between random1 and random2?

I apologise for a late reply Eise. I admit I swiftly browsed throught your post already yesterday but as soon as I saw "random1 and random2" I decided I will need Mr J. Daniels to answer so I waited for Friday evening. The answer is:

No.

Edited May 24, 2019 by koti

[The Shadow]

On 5/23/2019 at 6:15 AM, swansont said:

There's no way to test this.

Is that not just a simple, "thought experiment"? I am new here but am realizing (from your challenge, which may indeed be approprriate) that I may not fit in myself. I often type replies exactly as you challenged here (and elsewhere). I look for more engagement (word count especially) when I interact in a forum.

Not wanting a confrontation...just trying to predict my future interactions here.

Thanks

Edited July 11, 2019 by The Shadow
Typo

[Strange]

24 minutes ago, The Shadow said:

Is that not just a simple, "thought experiment"?

The trouble is that a thought experiment won't tell you what will happen, just what you think will happen. And, when the thought experiment involves something non-realistic (going back in time) we cannot know what would really happen.

[The Shadow]

11 minutes ago, Strange said:

The trouble is that a thought experiment won't tell you what will happen, just what you think will happen. And, when the thought experiment involves something non-realistic (going back in time) we cannot know what would really happen.

I understand all that but it is sad in a sense. Conversing, abstract ideas, can lead to "process of elimination"...some thought experiments simply do not gain traction, or support...they usually fade away. 

The internet is a challenging space for sure. I can say this. In 30 years I have participated in dozens of forums...camping, finance, autos, travel, gaming, cooking, etc. Science forums are difficult. For 30 years I used words like, "should" or "could". Never an issue. Science forums call me out ( as well as others) all the time:(

Lol...once on the Q forum, I commented on a gas giant in our solar system. I used the word, "environment" instead of, "atmosphere". 25 posts back and forth bickering for that poor word selection on my part.

Gets tiring quickly.

On 5/23/2019 at 6:15 AM, swansont said:

There's no way to test this.

Is not that just a simple, "thought experiment"? I am knew here but am realizing (from your challenged, which may indeed be approriate) that I may not fit in myself. I often type replies exactly as you challenged here. I look for more engagement (word count especially) when I interact in a forum.

Not wanting a confrontation...just trying to predict my future interactions here.

Thanks

Edited July 11, 2019 by The Shadow

[iNow]

The only correct answer is we don’t know and can’t find out. If there’s a specific phenomenon we wish to explore, find a way to explore it empirically.

You can think experiments all you want, but the poster asked a question seeking a definitive response when only speculative answers exist. 

[AbstractDreamer]

Actually I asked for the closest thing to true random, as I had assumed a definitive answer would be improbable.    I was hoping for a variety of examples that exist in the quantum world, because ultimately that's where I again assumed any randomness will originate from.   I was rather disappointed at there only being one answer (atomic decay), as I thought there would be more interesting situations where randomness is exhibited.

On the other hand, rather than looking at the randomness on the smallest scale, and look instead at randomness on the largest scale, such as the observable universe and how the different interpretations affect randomness on that scale.  Under Copenhagen interpretation, if the micro scale is not deterministic, then perhaps on the large scale there is greater non-determinism.  Just like one set of infinities can be greater than other sets of infinities.

Under Bohm, even if the quantum world is deterministic, can it be proved that this determinism is carried over through all the scales, despite being practically impossible to measure?  All it would take is one non-deterministic event to occur somewhere in the Bohm universe, and the deterministic nature of its quantum world would essentially be irrelevant in a volume that included such an event, and perhaps all "connected" volumes too.

Edited July 19, 2019 by AbstractDreamer

[Mordred]

Considering we can develop a probability function for any known quantum process it's not fully random. The likely hood of occuring can be statistically accounted for. I for one cannot think of any formula or process quantum or otherwise that would count as true random.

Edited July 19, 2019 by Mordred

[AbstractDreamer]

But do these functions only describe processes and their behaviour over time statistically?  For the next singular quantum event, are they still unpredicatable?

Edited July 19, 2019 by AbstractDreamer

[Mordred]

Let's take for example the annihilation creation operators under QFT. One can statistically predict the average number density of particles. Though one will never be exact. Nor will you ever be exact on when a measurable particle will pop into existence at a specific coordinate.

 We can however estimate within an error margin these processes. The better the predictions is reduction in systematic errors the less random the process becomes.

A true random process will have zero predictability.

Edited July 19, 2019 by Mordred

[AbstractDreamer]

So which processes have the most advanced predictions, the least systematic errors, but still a high degree of randomness?

How far can quantum randomness extend to the macro scale?

[Mordred]

Well one fairly easy to predict probability function would be the spin of an electron. As there is only two spin states you would have a 50% chance of getting it right.

Not sure how to answer the last considering macro processes can also involve a certain degree of randomness.

However I would surmise that once you can define an event by strictly Newtonian mechanics with discrete values you have left the realm of dealing with quantum states.

 For example you would be 100 percent certain of the position without influence of the Heisenberg uncertainty principle

 

Edited July 19, 2019 by Mordred

[swansont]

7 hours ago, AbstractDreamer said:

Actually I asked for the closest thing to true random, as I had assumed a definitive answer would be improbable.    I was hoping for a variety of examples that exist in the quantum world, because ultimately that's where I again assumed any randomness will originate from.   I was rather disappointed at there only being one answer (atomic decay), as I thought there would be more interesting situations where randomness is exhibited.

You were also given thermal noise.

[John Cuthber]

You can have photon emission noise too if you need a third option.

[Schmelzer]

On 5/23/2019 at 4:24 AM, Strange said:

(Hidden variable theories are ruled out by Bell's Theorem.)

No, only Einstein-causal hidden variable theories. There are deterministic hidden variable interpretations of quantum theory, de Broglie-Bohm theory.  They have to contain causal influences faster than light, but these cannot be used to send information.  

[Strange]

54 minutes ago, Schmelzer said:

No, only Einstein-causal hidden variable theories. There are deterministic hidden variable interpretations of quantum theory, de Broglie-Bohm theory.  They have to contain causal influences faster than light, but these cannot be used to send information.  

True. It rules out locally realistic hidden variables

[Enthalpy]

About computer randomness mentioned in the first post:

Software random function were historically (and still are mostly) pseudo-random. They are fully deterministic, in that, with the same seed they produce the same output sequence. Their "randomness" only means some statistical properties, and for cryptography applications, which are much more demanding, some difficulty to deduce future or past values from a known subset of the output sequence.

Finding a seed that is varied enough, hard enough to guess, is very difficult to program. This is a weak point in many crypto applications, for instance if the clock serves for this purpose, and an attack angle for cryptanalysts.

Recent Cpu propose a "true random" generator. I didn't see an accurate description of these generators. They could be built from thermal noise, shot noise... Physically random looks seducing, but tends to be very weak. First, physical biases like 0.1% are totally unacceptable in cryptography. Software post-processing eliminates the biases that the programmer has thought of (probability of 1 vs 0, correlation over successive bits...), but are there more? Then, is the physical state of the generator observable by other means, or can it be influenced? On a chip where the supply voltages vary brutally over time, the temperature too, isolating a generator must be difficult.