Is nothing truly random?

[LSJ]

By truly random, I don't mean it in the typical way, such the roll of a die or where an arrow lands.

Because which side the die lands on could be calculated if one had an impossibly complete knowledge of mathematics, matter, every force and their interactions. As though you were God (or whatever you want to call yourself), knowing everything.

Which side the die lands on depends on the weight of the sides, how it was held, the force used, the height it was dropped, the direction it was released, and so forth. The arrow could also be precisely calculated if you knew exactly the density of the air, every flaw in the arrow and bow and how it was going to interact with the surroundings after being released (etcetera of course).

As far as I know, the movement of every particle is related to the other particles around it, and forces within and outside the particle. And that these forces are not random. Electrons do not suddenly stop and change direction for no reason. Changing direction is caused by physical forces and could be calculated by Mr Awesome.

So, if everything works according to laws of physics, both known and unknown, then nothing is random and all could be calculated assuming it was possible for one to know everything about every single thing in the universe.

So this leads to an interesting thought: our brains are predictable. The neurons do not act randomly, they do things because of predictable reactions.

When someone chooses to say something, it could not have been any other way. If you played it back, and ran through the situation with every particle, every everything back how it was, it would run exactly the same way every time.

If you had ultimate knowledge and could track everything from the beginning, you could forsee the entire history of the universe. Every war, every gust of wind, every raindrop was a result of a predictable reaction all starting from a singularity at the "birth" of the present universe.

And again, when I say predictable, I mean if you were not part of the universe and had ultimate knowledge of everything. Not predictable by humans, but predictable by a divine supercomputer in a parallel dimension built from the hard work of nerds with an IQ of a billion.

[Bucket of Lithium]

You're correct partially, as even a random toss of the die without any before hand super knowledge will never be completely random. The way you throw it, the air etc. will affect it in a number of ways.

Random I think needs a proper definition, in this case something that happens spontaenously, without outside influence or cause. That pretty much excludes your examples as they are all something caused by people.

Whereas a random mutation within a bacteria can be seen as completely random. If we take away those caused by such external influences such as radiation etc. the bacteria will mutate or change eventually (depending on the species) in the natural way living things do, to evolve.

That could not be measured by any mathmatical devices, as the concept of random is just that, unmmeasurable as it is not, in the example I mentioned, caused by any variables TO measure.

[Playfishpaste]

entropy is the amount of disorder in a system, and it is a quantitative unit.

However, that doesn't make randomness any less random, just as measuring cold doesn't make cold any more mathematical. Randomness exists everywhere, for instance, it is completely impossible to predict meteorological interactions on a global scale. Even if you had all of the knowledge of thermodynamics, fluid dynamics etc. You'd get nowhere close.

[Simetrical]

By truly random, I don't mean it in the typical way, such the roll of a die or where an arrow lands.

Because which side the die lands on could be calculated if one had an impossibly complete knowledge of mathematics, matter, every force and their interactions. As though you were God (or whatever you want to call yourself), knowing everything.

Which side the die lands on depends on the weight of the sides, how it was held, the force used, the height it was dropped, the direction it was released, and so forth. The arrow could also be precisely calculated if you knew exactly the density of the air, every flaw in the arrow and bow and how it was going to interact with the surroundings after being released (etcetera of course).

As far as I know, the movement of every particle is related to the other particles around it, and forces within and outside the particle. And that these forces are not random. Electrons do not suddenly stop and change direction for no reason. Changing direction is caused by physical forces and could be calculated by Mr Awesome.

So, if everything works according to laws of physics, both known and unknown, then nothing is random and all could be calculated assuming it was possible for one to know everything about every single thing in the universe.

There are at least three problems with this.

One: it completely fails in quantum mechanics. As far as we know, there are some quantum-mechanical events that are absolutely random. The laws of physics tell us what the probability is of each outcome, but as far as we can tell, there is no way to determine in advance which outcome will actually occur, even with perfect knowledge. Although it's possible that we'll eventually figure out there really is some way to predict things, it seems very unlikely from our present vantage point. So your theory probably fails on its most basic premise, to start with.

Two: even if a system theoretically obeys deterministic rules, there are physical limitations on how much information you can store and how fast you can process it. Storing information creates entropy. Only a limited amount of information can be stored in any physical system with a given mass, temperature, etc. Desktop computers are now moving to 64 bits for storage pointers, and they may move to 128 bits (some filesystems already have), but they will never move to 256 bits. Physics prohibits the storage of anything on the scale of 2^128 bits in something the size and temperature of a desktop computer. Similarly, it might be physically impossible to store enough information on the Earth to predict a human's thoughts with total accuracy, even if you could ignore quantum-mechanical effects and had some way to precisely measure the whole state. You couldn't store it.

Three: even systems that behave in a simple, deterministic can be fundamentally unpredictable. Specifically, there are systems whose behavior is completely determined in theory, and very easy to calculate given an initial state, but which are chaotic. Even if you know the position and momentum of all particles in a fully deterministic system to 99.999999% accuracy, if it's chaotic enough, you'll have no idea where they're going to be five minutes from now. Any uncertainty at all, no matter how minuscule, will increase exponentially over time as you try to make predictions into the future. If you somehow knew the exact state of the system, then you might be able to predict it forever, but that might require an infinite amount of information. It wouldn't be physically possible, even ignoring quantum mechanics and information theory.

So in short: no, you're wrong. Sorry.

And again, when I say predictable, I mean if you were not part of the universe and had ultimate knowledge of everything. Not predictable by humans, but predictable by a divine supercomputer in a parallel dimension built from the hard work of nerds with an IQ of a billion.

As I said, it's probably impossible even for such a divine supercomputer to predict everything exactly. God does play dice ― and even if he's cheating, you're still not talking about a deterministic universe.

But even leave quantum mechanics out of the picture. The other two points I mentioned are enough to indicate that even in classical physics, a computer such as you discuss is physically impossible. Not just unimaginably difficult to build, but as impossible as water running uphill or heat spontaneously flowing from cold to hot. So I don't see this as being too different from the quantum scenario.

Random I think needs a proper definition, in this case something that happens spontaenously, without outside influence or cause.

That's not the definition he's referring to. The definition he's using is along the lines of "impossible to predict in advance, even given perfect knowledge". Quantum mechanics is random in this sense (as far as we know).

[Baron von Sky Hat]

What you describe is exactly how science thought things may be before important developments were made in a certain field: Quantum Mechanics.
You're also asking exactly the right questions regarding it. I'm under the impression that there was a lot of consternation regarding the concept of an entirely predictable universe, a universe whose path is already set in stone and unchangable.
I'm not good at the maths of quantum mechanics, it gets crazy complex. However, my understanding of the basic ideas behind it is the following:
Everything is probabalistic. There's no absolute answer to the questions of both where something is, and how fast it's going, you can't know both. More than that, not only can't you know both but the universe can't know.

All particles exist as probabalistic `wavefunctions'. They act as a kind of spacial map of what the probabilities of that particle existing at a particular location. The particles exist as a `blur' of places that they might be. They still interact with each other in the way you described, electric charge, gravity etc. however this happens for all of the `map' of their probable locations. Observation of such a particle `collapses' its wavefunction and it has a more specific position (of sorts).

This doesn't avoid the fundamental impossibility of knowing both the location and velocity (more technically momentum, velocity times mass) of the particle. This is defined by a relation called the `Heisenberg uncertainty principle': delta_x delta_p is greater than or equal to h / (4 * pi). Where `h' is plancks constant, a physical constant relating to quantum mechanics, `delta_x' is the uncertainty in the location, and `delta_p' is the uncertainty in momentum. If one measurement is very accurate (its uncertainty very small), then it forces the other one to be much less accurate (the other uncertainty becomes much larger), maintaining the relation.

An important and useful experiment for understanding QM is that of the `two slit experiment'. If you fire light from a point source at a pair of slits cut in an obscuring plate, then beyond that plate put a screen to catch the light, the light forms a pattern on the screen. Alternating light and dark bands, caused by the waves of the light interfering. If you think of light as a wave like this, entwined electric and magnetic fields, then at a certain point where two waves of light are, you can expect that the waves will combine, add up. If the wave of one `bit' of light is at its highest point, while the other is at its lowest point, they'll cancel out. Whereas if they're both at the highest point, or both at the lowest point, they'll double in whichever direction. Hence dark bands where they cancel out to an extent (destructive interference) and light bands where they strengthen (constructive interference)(whether it's the `lowest point' or `highest point' that they strengthen doesn't matter, the actual strength is the important bit, not the direction).

But you may say that light has already been considered to be a wave, thinking of light as a bunch of particles is difficult.

However, now do the same experiment with electrons. Very conventionally thought of as a particle, but they form exactly the same form of patterns, interfering with each other.

That alone is quite extraordinary, these things act both as particles and as waves, which applies depends on the situation, but they're fundamentally both. However there are other interesting aspects of the same experimental setup. Reduce the flow of electrons from the source until you know that only single electrons are coming out at any time, and make the screen at the far side record how many electrons are hitting it where. Any given electron will form a single dot on the screen. However, as you let these build up over time, even though only one is going through the slits at a given time, the same bands will emerge, with more electrons hitting certain parts of the screen than others.

How can that happen? The electron is interfering with itself, effectively having gone through both slits, its probability wave forming the same interference based shape, then, only when it's measured and affects something else at the screen, it collapses to a single location and makes a single dot. But where that dot is likely to be is based on its orignal wavefunction as if it had gone through both slits and interfered with itself.

Still weirder yet though! Now, we put a device at the slits that measures if an electron passes through. What happens? The wavefunction collapses at the slits instead, it doesn't have a chance to interfere with itself, and the light-dark pattern generated on the screen doesn't happen!

That's the basics, as I understand it, and as well as I can express it. I've modified what I understand of it a bit in order to avoid much maths that I do know of QM, so I may very well have messed up a little. Also, that's assuming I actually understood it in the first place...
So either way, my explanation isn't great, and I didn't mention any of how Quantum Mechanics actually came about, nor why it's `Quantum' (it relates to `quanta' a single bit of something, in this case refering primarily to the fact that all energy is in discrete `bundles', bits of energy that can't be subdivided. This is the fundamental aspect of quantum mechanics, basically from this all of the maths rolls out to form descriptions of all the other stuff I've mentioned.)

Hopefully it's of interest. For more information, fuller and likely more reliable, the following pages might be useful:
http://en.wikipedia.org/wiki/Quantum_mechanics
http://en.wikipedia.org/wiki/Heisenb...inty_principle
http://en.wikipedia.org/wiki/Two_slit_experiment

Also I'd recommend hyperphysics. More reliable than wikipedia, and better explanations of some things. Though occasionally fairly specific stuff, without overviews of the topics. Very very good site for physics stuff though.
http://hyperphysics.phy-astr.gsu.edu/hbase/HFrame.html

It's also important to mention just how accurate QM actually is. Determining how things will happen in a quantum mechanical manner is very successful. It won't tell you what will happen, but it tells you the probability of outcomes, and by building up measurements like with the electron experiment, it predicts it with incredible accuracy. Look at the following (or locate within hyperphysics) for a description of `Quantum Electrodynamics', famed for just how precise the experimental accuracies in it are.
http://en.wikipedia.org/wiki/Precision_tests_of_QED


I've not dealt with the other points Simetrical mentioned. I agree with him that, even in a deterministic universe, the information is simply too much to contain without something as large as the universe itself to store it on.....
However that's only from the computer front. From the `thought experiment' front, it is a valid idea as, although not practically possible, it's conceivable. The universe `knows', as it were, and hence if the universe was deterministic, then there would be a predefined outcome. However, as mentioned and as I've described, QM seems to show that the universe is not deterministic.

[Simetrical]

A few nitpicks . . .

Everything is probabalistic. There's no absolute answer to the questions of both where something is, and how fast it's going

There is an absolute answer ― it's just a probability distribution, instead of a single number. That's an important distinction to keep in mind. Terms like "indeterminacy" are kind of misleading. In fact, if you buy the many-worlds interpretation (I'm partial to it), then there really is a definite answer: every possible point on the distribution occurs. You observe all of the outcomes, just in different worlds.

you can't know both.

A very bad way to phrase it. Unfortunately conventional: the "uncertainty" principle has a horribly confusing name.

Better to phrase it like this. In quantum mechanics, a particle does not have a single three-dimensional position or momentum. Rather (simplifying slightly), it has a whole distribution of possible positions and momenta, each with a specific probability. The uncertainty principle states that if the distribution for a particle's position is narrower (i.e., it's likely to occur somewhere in a small region), then the distribution for its momentum is broader (i.e., it's likely to take on a wide range of values), and vice versa. That principle also applies to many other pairs of quantities in quantum mechanics, like (IIRC) the overall magnitude of angular momentum vs. its magnitude in one direction. (Any two measurable quantities whose operators don't commute.)

If one measurement is very accurate (its uncertainty very small), then it forces the other one to be much less accurate (the other uncertainty becomes much larger), maintaining the relation.

You shouldn't focus on the concept of measurement here. Particles obey the uncertainty principle (I really wish there were a less misleading name) regardless of whether anyone measures them or not. It's a matter of how the particle actually is, not just a matter of how it can be measured.

That alone is quite extraordinary, these things act both as particles and as waves, which applies depends on the situation, but they're fundamentally both.

Better to say: they're fundamentally neither. Both classical particles and waves have a single position that will remain consistent in their interactions with other things. Quantum particles don't. The electrons pass through all the slits at once, and each interferes with itself; but then when they interact with complicated things like electron detectors, only one detector goes off. That doesn't match the behavior of either a particle or a wave. It's less misleading to think of them as having a unified, definite identity that just doesn't match anything in classical physics ― comparisons to classical waves or particles can be useful approximations in some cases, but they're only approximations and should not be treated as representing the basic nature of things.

I've not dealt with the other points Simetrical mentioned. I agree with him that, even in a deterministic universe, the information is simply too much to contain without something as large as the universe itself to store it on.....
However that's only from the computer front. From the `thought experiment' front, it is a valid idea as, although not practically possible, it's conceivable. The universe `knows', as it were, and hence if the universe was deterministic, then there would be a predefined outcome.

It's conceivable, but it's also conceivable that quantum mechanics obeys some nonlocal hidden variable theory and is deterministic after all. Given our current knowledge, we have no reason to put much weight on such remote conceivables, in either case.

[Vizsla]

So for human thought to be random, and therefore free and not predetermined, it must either be Quantum or Chaotic?

[Baron von Sky Hat]

A few nitpicks . . .

Agreed on pretty much all of your points. I'm aware of most of those bits and pieces already, it was more my lack of ability to correctly express it at the level I was aiming for. I'm not the best at adjusting something I know into a good explanation.

There is an absolute answer ― it's just a probability distribution, instead of a single number. That's an important distinction to keep in mind. Terms like "indeterminacy" are kind of misleading. In fact, if you buy the many-worlds interpretation (I'm partial to it), then there really is a definite answer: every possible point on the distribution occurs. You observe all of the outcomes, just in different worlds.

Definitely agree with the `absolute answer' being a probability distribution, but felt that that would be an unnecessary complication to the explanation. Considering, by and large, people consider an absolute answer to be a single number, I felt it would have the same effect.

A very bad way to phrase it. Unfortunately conventional: the "uncertainty" principle has a horribly confusing name.

Better to phrase it like this. In quantum mechanics, a particle does not have a single three-dimensional position or momentum. Rather (simplifying slightly), it has a whole distribution of possible positions and momenta, each with a specific probability. The uncertainty principle states that if the distribution for a particle's position is narrower (i.e., it's likely to occur somewhere in a small region), then the distribution for its momentum is broader (i.e., it's likely to take on a wide range of values), and vice versa. That principle also applies to many other pairs of quantities in quantum mechanics, like (IIRC) the overall magnitude of angular momentum vs. its magnitude in one direction. (Any two measurable quantities whose operators don't commute.)

Again, with the uncertainty principle stuff, I know that it's not quite how I put it, that was one of the bits I was particularly unhappy with my phrasing. Certainly I like your description better in terms of accuracy, and very nice and concise, but may be a bit complicated for general consumption?

You shouldn't focus on the concept of measurement here. Particles obey the uncertainty principle (I really wish there were a less misleading name) regardless of whether anyone measures them or not. It's a matter of how the particle actually is, not just a matter of how it can be measured.

Agreed, I did over focus on the idea of measurement somewhat, rather erroneously unfortunately, but was easiest way I could think of explaining it at the time.

Better to say: they're fundamentally neither. Both classical particles and waves have a single position that will remain consistent in their interactions with other things. Quantum particles don't. The electrons pass through all the slits at once, and each interferes with itself; but then when they interact with complicated things like electron detectors, only one detector goes off. That doesn't match the behavior of either a particle or a wave. It's less misleading to think of them as having a unified, definite identity that just doesn't match anything in classical physics ― comparisons to classical waves or particles can be useful approximations in some cases, but they're only approximations and should not be treated as representing the basic nature of things.

I considered saying that they were neither, as that is how it's presented at university courses (mine, at least) and how I've always seen it. I think I should have stuck with it, as you say, they're their own thing entirely, and it's our lack of a real world analogue that results in an inability to conventionally describe them.

It's conceivable, but it's also conceivable that quantum mechanics obeys some nonlocal hidden variable theory and is deterministic after all. Given our current knowledge, we have no reason to put much weight on such remote conceivables, in either case.

Obviously you wouldn't be able to draw any reasonable conclusions from such a concept, and in this case it may be that anything you could infer from the concept would be extremely limited, but conceptual thought experiments permeate physics, especially things like QM. Mostly to demonstrate principles (Schrödinger's cat and the like), but you could equally use this concept to do the same.

So, yeah, I agree with all of the things you pointed out, they are definitely inaccurate, but in most cases it was through poor explanation rather than misunderstanding. People may be skeptical as to whether I genuinely did understand them, as anyone can claim afterwards that `Oh, yeah, that was what I meant... honest....' but hopefully you're willing to believe me

[Simetrical]

I'd say that's a very confused way of putting it.

First of all, randomness doesn't imply "free will". It implies no more "control over your actions" than determinism does. In any case, your actions are decided completely by the laws of physics on a fundamental level. The only difference is whether you could predict it in advance, or not. In either case it's not "controlled" by "you" in some way not reducible to purely physical interactions on the level of particles.

Second of all, human thought cannot "be quantum". It arises from the laws of physics, which are (as far as we know) fundamentally quantum. In some cases the quantum effects are important, in some not. Human thought might be subject to a good classical approximation, or not. In either case it's not deterministic, just perhaps nearly so.

You should not try to explain "consciousness" or "free will" in terms of physics. They're much higher-level concepts than that. Better not to worry about them at all, in my opinion; but if you really do care about whatever they are, then go read some philosophy books. Physics doesn't have a lot to say that's interesting.

[Maximus Macro]

haha this isn't quite the kind of conversations that occur where i live:p Damn Flemmish hicks