Probability and Unbiased events.?

This question is only for the enlightened ones! This was supposed to go in Physics section but somehow went to Maths one. So reposting over here.





Can we truly have an unbiased event? All events which we call as unbiased are so because we cannot, at this stage, account for all the forces affecting the outcome.


For example, tossing a coin or rolling a dice is not an unbiased event as the outcome for the same can be predicted if we know all the intial conditions and the forces acting on coin/dice.


So can we really have an unbiased event? Some long ago told me that it happens in the world of quantum mechanics, but I am not sure.


Can someone throw some light on it?

Probability and Unbiased events.?
Heisenburgs Uncertainty thought experiment said that our observation of the particles disturbs them. But this view of uncertainty, ie shining a light on an electron to observe it disturbs is, has been proven wrong by way of the EPR Paradox, which basically works by measuring an entangled twin particle, so the other, experimental, particle isnt disturbed. Even when we do this, the Uncertainty still remains, although we dont directly disturb ithe particle. EPR stands for Einstein, Podolsky, and Rosen. the link below has a decent explaination...entanglement is a tricky concept and might make you ask more question than it answers, but thinking is good!
Reply:See the early part of the reference for an explanation of what the Heisenberg uncertainty principle claims. The limit is not a limit on our ability to measure initial conditions, but is a more fundamental limit.





The position of an electron in an orbit can be one of several possibilities. We represent this with the superposition of the wavefunctions of all those possibilities. The Heisenberg claim is that, for a specific electron, there will never be any experiment you could perform to determine which of those states represents it. So, this could be considered an unbiased event, but not useful since you'll never be able to measure it.
Reply:Depends on what we define as biased/unbiased. Clearly a fair coin will map out a probability distribution curve (a normalized frequency curve) that will reflect (more or less) 50% of the tosses will be heads and 50% will be tails.





In stat talk, that's unbiased by definition. But one could argue that it's really biased towards the 50-50 outcome. By convention, we don't do that. Thus, if after 30 or more tosses of that coin we find a 20-80 distribution, for example, we, by definition, would call that biased and the coin is not fair.





Similar thing for that one dice...we roll M times and find the normalized frequency distribution to be uniform across all six numbers (outcomes). In that case, we'd call the distribution unbiased and the dice fair. But, if the number 1 for example, came up four times more than any of the other numbers, we'd say the dice was unfair and the distribution biased towards the number 1.





In quantum mechanics, the quanta (e.g., electrons) have probability density distributions with standard deviations in location and in momentum. And, according to the Heisenberg Principle, only one of the two (location or momentum) can be measure with any certainty...the other one would be uncertain.





Thus, the unbiased outcomes in QM would follow the distributions and Heisenberg Principle of uncertainty. If experiments came out with outcomes that belied these, the results would be biased. Sometimes it's the bias that indicates a causative factor that needs to be identified. In other words, if the expected distributions do not occur, there may be something causing that bias...like an unfair (crooked) coin.
Reply:for what it is worth.


unbiased events have probability equal to number of possible outcomes in the sample description space.


biased events have different weights on the outcomes in the sample description space..
Reply:It sounds like the someone was referring to Heisenberg's Uncertainty principle. Quantum events are based on probabilities. There is no way of knowing the exact location and momentum of sub-atomic particles, because the act of measuring anything that small disturbs it. Even one photon striking an electron causes a change in its position, an uncertianty that can't be measured. Thus though cause and effect are in effect, it is unbiased because there is no fixed pattern from which to know the outcome of future events.
Reply:Hi,





It would probably help for you to investigate the details of quantum mechanics in a little more detail. Heisenberg's uncertainty principle does not state that we can't measure or predict the interactions due to a technical limitation. Rather, it describes how accuracy in taking one measurement fundamentally alters a system such that knowing another, related property accurately is impossible. Thus it is FUNDAMENTALLY IMPOSSIBLE to measure a system in a way that eliminates uncertainty. There is no way beyond this limitation; there are no by-laws of physics.





So, there is no way to describe a system in total certainty; thus, there is no way to predict a system's behaviour with total certainty. However, the odds of a certain event occurring in a certain amount of time -- that is, the probability of an event -- can be accurately and consistently determined.





Incidentally, while quantum unpredictability can only happen with noticeable frequency at subatomic scales, it does have a measureable effect on our macroscopic world. Schrödinger's Cat is a thought experiment that examines the ramification of large scale events (the life or death of a cat) based on quantum uncertainty-based events like radioactive decay. And, even in environments we consider pretty deterministic (like billiard tables) we find many, small, conflicting, turbulent forces that make it impossible to predict, no matter how carefully it's set up.





So we never get away from uncertainty. Everything is a roll of a loaded die.
Reply:imangine we are rolling afair of dice. There are six equally outcomes:1,2,3,4,5and6.What is the probubility of getting a five.Well 1over6 is not a lot so you'll get the propubility of not getting a six because 5 more that you can get

vampire teeth