Random movement of particles or other things?

[squeehunter]

Bear with me, I am not a scientist. Also, this is NOT a question about free will. I wanted to know if particles ever move in random directions. Since I know there will be an issue of semantics here, I will give some examples:

Two separate universes (when I say universe I mean, "area where stuff happens"), not the technical term). Each universe has two atoms traveling at each other than the same speed/direction. In each universe, when they hit, are they going to bounce off of each other and go the same direction? Or will it be slightly different for each?

Another example:

Two separate universes. Each universe has a single celled organism with a flagellum in some kind of liquid in a glass bubble. Will each universe play out the same way with the life cycle and movement of the organism or will there be something that causes randomness for it to play out differently in each?

In summation, in case particles like atoms don't behave this way, is there anything random in the universe that could cause a change in the way two scenarios play out differently in separate, unconnected experiments?

 

[DrChinese]

Bear with me, I am not a scientist. Also, this is NOT a question about free will. I wanted to know if particles ever move in random directions. Since I know there will be an issue of semantics here, I will give some examples:

Two separate universes (when I say universe I mean, "area where stuff happens"), not the technical term). Each universe has two atoms traveling at each other than the same speed/direction. In each universe, when they hit, are they going to bounce off of each other and go the same direction? Or will it be slightly different for each?

Welcome to PhysicsForums, squeehunter!

The answer to the question, as I think you are intending to ask, is NO.

With the same input situation, you do not get identical results each time at the quantum level. What is identical is the likelihood of the various outcomes. The actual outcome will be one of the possibilities.

 

[squeehunter]

Thank you so much Dr. Chinese. This one might be a little more confusing though. I want to know if the quantum randomness could affect larger? things if given enough time.

Two universes, each with billion gallon cereal bowls full of alphabet cereal. Let the "simulation" run for a million years. Will they spell different words after that one year mark? A silly experiment but you know what I mean.

 

[DrChinese]

Thank you so much Dr. Chinese. This one might be a little more confusing though. I want to know if the quantum randomness could affect larger? things if given enough time.

Two universes, each with billion gallon cereal bowls full of alphabet cereal. Let the "simulation" run for a million years. Will they spell different words after that one year mark? A silly experiment but you know what I mean.

I would absolutely expect them to be different. It would be quite surprising if they weren't!

 

[Archosaur]

The letters will have long since become too mushy to read.

In all seriousness though, you are asking a legitimate question. It's true, randomness depends on scale, and on our scale, it's all but not there. However, the universe is a good example of a "chaotic system," which is one in which the final state depends heavily on the initial state. Another example of a chaotic system is the infamous "double pendulum" which is, as it sounds, a pendulum with a pendulum at the end. To use your definition of "universe", if you have two double pendulums (pendula?) in two separate universes and you start them swinging in exactly the same way, but a fly bumps into one of them, you won't be able to tell a difference at first, but if you come back a million years later, the two double pendulums will be doing completely different things.

Our universe is much like this. As you go back, closer and closer to the big bang, the scale of the universe becomes such that quantum nastiness plays a larger and larger role. The formation of stars and galaxies depended heavily on the slightly asymmetrical distribution of matter throughout the universe, which was highly dependent on quantum "jitters" (i.e. randomness).

So, if you somehow restarted out universe from time 0, you would certainly get different stars, different galaxies, different life.

But you weren't asking about time 0, you were asking about two systems that are of large scale from beginning to end. You start with a bowl of letters, you end with a bowl of letters. Again, the larger the scale, the less quantum randomness has to do with anything, but, regardless of scale, it never has no influence. I'm sure that you would eventually see noticeable differences, but I can't even begin to guess how long that would take.

Also, Dr. Chinese, I love your Einstein quote!

 

[squeehunter]

And they would be different because of the quantum randomness right? It's a given but they both start off exactly the same but you probably knew that. I just wanted to make sure. If those are both yeses, then you have answered all of my questions and I thank you.

 

[Archosaur]

Yes.

Welcome to Physics Forums.

 

[squeehunter]

Thanks Archosaur too. I didn't see your message before I asked my other question.

 

[squeehunter]

As sort of a thought experiment, in the incredibly^10 unlikely event that things would "jitter" in some kind of meaningful way, could larger, more recognizable events happen?

I've forgotten how nuclear decay works, but would it be possible (again incredibly unlikely) that each atom of Uranium in a block of it, would lose a neutron at once, therefore creating a large heat increase, instead of a slow and steady one? This would basically never happen but I want to understand the way this randomness works.

[edit]

Lastly can anyone tell me what this randomness is capable of? I've heard of nuclear decay obviously, but what else? Will particles move at random angles when pushed or will electrons be in different places at a given time meaning something might or might not bond to something else? I'm just not sure what his all entails.