# Can someone please explain to me how randomness is possible constrained by causality

1. Feb 21, 2012

not to be impolite, but i truly view randomness in reality as something you can trick your kids into accepting along with santa, the tooth fairy etc.

when compared to causality the idea of true randomness existing in reality seems incredibly weak to me.

is there any simple logic which can reconcile the two?

2. Feb 21, 2012

### Matterwave

Re: can someone please explain to me how randomness is possible constrained by causal

Are you calling the foundations of quantum theory incredibly weak?

Randomness and causality are not really opposed to each other. Perhaps randomness and determinacy are, but not really causality. Things can be random and still cause other things to happen. Can you explain in more detail what you mean?

3. Feb 21, 2012

Re: can someone please explain to me how randomness is possible constrained by causal

i dont think you followed. random, is what we call something when we have no idea of its cause. so by your example that things can be random and still cause other things to happen, you will ultimately have to trace it back to its original cause which by randomness has no cause, so all following events will be random.

also i dont know how you can distinguish causality from determinism. determinism is a direct result of causality.

4. Feb 21, 2012

### lalbatros

Re: can someone please explain to me how randomness is possible constrained by causal

You could have some insight by some readings about "random number generators" (rng).
You have very likely used -knowinggly or not- a random number generator.

An rng follows a perfectly deterministic process.
However, you might not know what this process (algorithm) is.
Furthermore, if you knew the algorithm you might still not be able to predict the result of the rng, simply because you may lack information about the initial value or the key that was used, or anything else.

In summary, you will quickly realise that randomness can often be related to a lack of information. This lack of information should not be seen as a failure of science. Nor should it be seen as a cheap story to hide difficulties. Recognizing properly the lack of information and its role in our analysis of the world is, on the contrary, I believe, a pillar of science.

I would even not be surprised that the whole quantum mechanics could also be approached in this way. It has already be hypothesed that the "wave function" is not a "real" physical object, but instead a mix of physical reality and of the information we have on this reality.

Only kids may learn more on this, for they have less prejudices.

5. Feb 21, 2012

Re: can someone please explain to me how randomness is possible constrained by causal

what you just said doesnt disagree with any of my beliefs. could you explain ur lastparagraph further tho, its interesting.

6. Feb 22, 2012

### lalbatros

Re: can someone please explain to me how randomness is possible constrained by causal

Quantum Information is a hot topic today, as you know.
There are hundreds of books and maybe millions of paper published on this topic.
You may easily find references on Amazon that could suit your mindset.

Do not forget to read about Bell's theorem and Alain Aspect experiment.
This might shake deeply your POV on randomness, as these imply that quantum randomness cannot be reproduced by a classic system (and therefore also not by a "classic' rng).

Quantum computing may look like a 'technical application' of quantum mechanics.
I think it is much more than that.
I strongly believe that this field will come with new deep insight in physics and into the understanding of "randomness". After all, states of a "quantum computer" are just states of a quantum system.