Well that depends what you mean by "just a perception". Consider the classical example, a die roll. The physical processes which control which number comes up are totally deterministic, but they are chaotic, so tiny changes in initial conditions result in massive changes in end results. We almost certainly never have enough information to predict the result accurately, the lack of information we have represents some uncertainty in our knowledge of the initial conditions, and since small changes in initial conditions change the outcome massively it becomes impossible to predict the outcome. The process is thus random. In other words randomness is about probability and information theory, it isn't a physical thing. So in that sense it is "just a perception", if you like, it is something that exists in our minds. That said, it is still an extremely useful tool/model for predicting outcomes in the face of incomplete information. Then of course there is quantum mechanics, which changes the game a bit and perhaps makes it fundamental physics after all.
wouldn't it be physical if the motion of electrons is random? or maybe not since they aren't random when acted upon. though lack of information makes things seem random, what i want to know is if anything is actually physically random.
I think the three-dimensional real ,lifeless univers is causally deterministic. So there is no random. But life induces in this universe the "random". Although the processes in which is involved life, is random.
This is a big can of worms that we've explored quite extensively here and here. It would help if you explicitly define random, which isn't as easy as you might think. It seems most folks hold the opinion that "classical" physics is deterministic and therefore not random, while quantum physics adds an element of apparent fundamental "unknowability" in processes that break this determinism and are therefore random. I personally think randomness is subjective to a knowledge set, and "true randomness" does not exist despite quantum influences.
so is it "life" that is the monkey wrench in this deterministic universe? is that what causes seeming randomness? for instance, i can choose to turn right instead of left but the universal principles are not based on choice. so random is just contextual?
those "tiny changes in initial conditions" are only random if they are caused by choices? choices can only be made by "lifeforms" as far as we know here. if those changes or factors are not made by choices/actions based on will, then everything is deterministic and the future is already set in stone. for instance, we know the sun will die in a few billion years. so we only experience randomness because we can affect change in a limited context, is that right? when one casts a die, their intention may be to throw a certain number but that is not in their control since they are not aware of all the factors as well as not being in control of those factors or changes. the cause and effect due to the principles of physics is totally deterministic minus the fluctuations caused by what? choices?
Well their motion isn't totally random, it is well explained by quantum mechanics, but you predict things with quantum mechanics by calculating probability distributions, so you only ever know the probability of something happening. Since this is the deepest description of nature we know it sure seems like it is a real physical phenomenon, yes. Lack of information making things seem random is what most people take as the definition of random. If your system is one where a slight lack of information destroys your ability to predict outcomes then it is considered random. No, it has nothing to do with "lifeforms" or conscious decisions or any such things. Think jurrasic park Please Register or Log in to view the hidden image!, when the mathematician is explaining chaos he drips a drop of water onto the back of his hand and watches it roll off in some direction, then does it again and it rolls a different direction. You could do the same thing with no living thing involved, get a funnel and drip some water onto a smooth hemisphere or something and if you get it right in the middle you won't be able to predict which way it will roll off. Or just think about trying to predict tomorrows weather, or what balls some machine will draw out of a lotto machine, or anything like that. This is an entirely different question. Randomness can exist just fine in a totally deterministic universe. We still can't predict the outcomes of most things with certainty, no matter how set in stone they are in some philosophical sense. That is philosophy, and is not particularly relevant for science. No, not choices, chaotic processes, basically any system that isn't extremely simple will exhibit some kind of chaotic behaviour. Yet chaotic behaviour can still be understood probabilistically, we use statistical concepts such as randomness to help us examine crazy chaotic systems at a different level, where things can be understood more simply, while we sweep all the irrelevant stuff that is too hard to work with away into a nice neat package of variables we describe as "random". Consider a simple concept like temperature. This is a large scale phenomenon resulting from the chaotic motion of vast numbers of gas particles (say), yet we don't need to worry about what every gas particle is doing all the time to be able to do useful things with large scale average properties, such as their average kinetic energy, which gets us temperature.
I thought that was just an example and you were speaking more generally. Conditional on our knowledge of physics not being totally wrong, yes the sun dying in the future is a certainty Please Register or Log in to view the hidden image!. I'm not really sure why that is relevant though. I guess it is an example of large scale certainty existing despite small scale randomness; the sun is a very chaotic beast, e.g. we can't predict exactly when some giant flare is going to toss a huge blast of solar wind our way and destroy our communications infrastructure. Yet none of that small scale randomness is important for predicting that the sun will die someday.
Technically, our physics knowledge being completely wrong has a non-zero probability. So is the chance that a rogue solar system will collide with ours, providing our sun with more fuel. So is some sort of time-slowing or time-stopping event that would "prevent" the sun's death. Point being, "almost certainly likely" is still a probability, not a deterministic future (even though, as I said, a deterministic future could still exist in my opinion, it's just that we cannot know what that future is).
That's why I said 'conditional on'. And to address your examples; the sun will still die someday even if it gets extra fuel somehow, and some kind of time-stopping event would imply physics has serious problems so is the same as my condition. i.e. P(sun will die someday | physics is not extremely wrong) = 1 of course this does not mean P(sun will die someday) = 1 however the truth of such absolute statements is always unknowable.
Kurros, I was explaining your point further rather than refuting it. The OP is asking about absolute certainties and the way your wrote your post may be interpreted by someone less familiar with probability theory as being such a statement.
