Acutally dice are very bad at being random:

http://www.dakkadakka.com/wiki/en/That%27s_How_I_Roll_-_A_Scientific_Analysis_of_Dice And even vegas dice need to be exchange every X number of throws because the corners become rounded.

Then let me assure you that you have no idea how much randomness is in weather ;) Starting with turbulences which are so devilishly random motions that we cannot predict them at all! We do observe them but cannot predict in advance!

And as for the lightning... believe me - it's not so simple. And everything which is so brief will be subjected to uncertainty principle and yet again we reach the quantum mechanics ;)

I know that physics seems to be deterministic but it's not. Take laser as an example: it seems to be very deterministic - you press the button and it's shining. But it's not enough that you applied some voltage. Without the random fluctuation of an energy there will be no laser action in the first place!

If you have a radioactive isotope, how long will it take to decay? The answer is that there's no way to say; it's a random process.

I mean, I suppose that if you're a religious type you could say, no; everything was preordained by God, including "random" quantum phenomena, so there is no randomness in the universe. Short of that, you're not going to get a purely deterministic universe.

I'm pretty sure they said the same thing about Sun eclipse few hundred years back.

I am not religious person, but assuming that we see things as being random because we don't know yet how to measure and predict them, is not stupid assumption..

Those are not very good examples. Neither the weather nor traffic jams are purely deterministic nor probabilistic events. They are deterministic enough to enable us to give reasonably accurate predictions provided we know enough of the variables to feed into our model of the system (and the _model_ is deterministic). But you'll never be able predict real-life results with 100% accuracy.

You could, theoretically, argue that both phenomena are in fact deterministic and that our understanding of them just isn't sufficient to see that. But that is a philosophical stance rather than a scientific theory, and it's mostly moot since in practice it doesn't matter if we can't determine the weather because it isn't deterministic, or if we can't do so because our model is too simple. The effect is still that you're sitting in the rain with your picnic basket. ;)

I think it's a good ending point in that debate ;-) Well said, well said.

I have to repeat myself: the very nature of quantum mechanics is probabilistic. It's a scientific fact, we cannot argue about that point. There are some phenomena that we cannot predict and we know with certainty that we will never be able to do so - because we are sure that they are purely statistical phenomena! No place for any assumptions - we already have proofs for that ;)

The first time someone was able to predict the eclipse of the Sun was, I believe, about 600BC.

And I didn't say it was stupid; very intelligent people worked with deterministic models for thousands of years. But at the same time, if there's absolutely no reason to think quantum events are secretly deterministic, then you're basically putting yourself in the "God does not play dice with the universe boat"; you don't like the idea of randomness, so you reject it even though there's nothing more convincing to replace it with.

It is a "scientific fact" as long as we accept the central axioms of quantum mechanics as irrefutable truth. The history of physics tells us that there may be more subtle phenomena that we do not understand yet which require a more sophisticated model. So, working in the framework of quantum mechanics, we will never be able to predict some events, but I would not dare to say that quantum mechanics is the ultimate truth.
For all intents and purposes today, this matters very little, of course, as the theory is consistent so far.

Knuth has a good discussion of randomness as it relates to computers.

However, I don't think computers can do "truly" random, unless they have special hardware. I believe lots of algorithms use some sort of seed number from which the random number is generated, so the number generated is not totally independent of previous numbers. (To the best of my knowledge).

You're probably better off rolling a dice :D (roll two D10s and there are 100 possible outcomes).

I simplified my answer too much and you immediately reacted ;) Yes, you are right about it, quantum mechanics may be challenged at some time. But nevertheless some aspects are more certain than the other and some proof are so strong that we may quite safetly assume them to be a natural law. Uncertainty principle is a good example and it's all about randomness ;)

But it's not! Quantum mechanics and relativity are contradictory to each other! There are some aspects in both theories that we are sure about (as I described above) but some others are contradictory. So the fact is that we know even now that the quantum mechanics is not a flawless theory. There are intensive studies performed worldwide to create an unified theory which will compromise both quantum mechanics and relativity.

"... and so finally the ancient debate between supporters and opponents of random.org was settled forever."
- Encyclopedia Galactica, 1182 FE.

Thank you very much for your help, Ghorpm, I really appreciate it! I marked your post as the solution.

This thread can serve as reference for when someone has the same doubt in the future.

Also, thank all other participants for their suggestions, comments and the interesting discussion that followed.

You are welcome!

Sorry, to 'resurrect' (is it a necro if the body is still warm? ;-P ) this thread, but your comment about birth dates has intrigued me, Psyringe. Why is 19 chosen much more often that other numbers? Does people be born more often in the 19th than in any other day of the month? I was born in a 16th... am I a freak of nature?

(Don't answer the last question, I already know the answer. ;-P )

No, I just borked up my explanation, I guess. With birth date, I meant the full date, including the year. So, if (say) you're born on the 16th of August in 1990, then you might pick the numbers 16, 8, 19, and 90 (or 9, if 90 isn't available) in a lottery. Since lots of people do this, and lots of people were born in the 20th century, "19" is probably the most-chosen number in lotteries. You can show, by statistical analysis of public lottery data, that numbers in the "upper range" (higher than 31) usually lead to fewer winners, with respectively higher individual payouts. That's because the large number of date tippers causes an overrepresentation of the numbers 1-12 (month number), 1-31 (day), and especially 19, in the numbers chosen by the participants. Over time, "20" will take over the dominant role that 19 currently has.

Funny side note 2: I remember that the official lottery in my country (pick 6 numbers out of 49) once had a very strange looking result, basically all 6 numbers were close together, and some were neighbors. The media was already wondering if anybody had actually chosen such an odd selection of numbers, when the lottery made the announcement that this week had resulted in more winners then ever. Apparently, lots of people chose numbers arranged in a _letter pattern_, and the numbers of this week were forming the letter "H" or "N" on the lottery slip where you marked your numbers. Lots of people thought they were millionaires because they hadn't imagined that anybody else would choose such an odd pattern; in the end, everyone of them received about 5,000 Euro.