Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What do I know I'm a lowly engineer

  1. Dec 31, 2004 #1

    I am not a physicist by training I'm an engineer so please bare witht he glaring gaps in my understanding and descriptions of the principles I'm concieving.

    I had a quick a question that could resolve a conflict I've been having. If the answers to a few basic questions are incongruent to the understanding I've been wroking under then I won't even need to trouble you all with larger convoluted question.

    simple questions:
    my first question is do principles of Newtonian Causality apply at the sub-atomic level?
    my second question is are all sub-atomic particles subject to stable field dynamics?

    not so simple question:
    If the answers to those questions are yes, then I've encountered discrepency in my personal perception of reality, which may simply be the result of a gap in my understanding of quantum mechanics. If the sub-atomic particles that make up our body are just following dynamic patterns then how does concept of "choice" or "will" exist? If our thoughts are the results of field interactions in our brain-sponges, then wouldn't that mean that our thoughts are just the progression of over-lapping threads of causality at the sub-atomic level? And our concept of reality just a blanket of illusion over a mass of vibrating particles, participating in their own dynamic confluences reguardless of what anyone "wants" or "feels"? This leaves me at a fork in my understanding. Either I'm way off base and have no idea what I'm talking, or there is a different sort of physics occuring inside our brains. Please, help me physicists!! My engineers perspective has destroyed my concept of choice, I want to see the universe as a perfectly ordered set of interactions and procedures, a sure sign that my education as an engineer has penetrated the the inner layers of my consciousness. I'd also like to note that I was classically educated, greek philosophy and salic social precepts, so I belive in choice, I just can't reconcile it to my current understanding of physics. Thank you taking the time to read that mess.
  2. jcsd
  3. Dec 31, 2004 #2

    Kane O'Donnell

    User Avatar
    Science Advisor

    Are you talking about determinism? That is, if we knew everything about the universe at a particular time, we can predict the entire future using a set of physical laws?

    If so, then unfortunately for you, determinism was shot in the foot by QM to a certain extent. That is, even if effect follows cause, the question of *which* effect is still a question of probability.

    At nanoscales this becomes much more prominent and is the reason why we can have things like stable atoms. On the other hand, at macroscopic levels the probabilistic nature of QM becomes much less pronounced. That is, we *can* set up approximately deterministic macroscopic systems, for example, a Hi-Fi circuit, a car engine, etc. That is, we know that over the (relatively short) time periods over which these things will operate (tens of years), we can predict how they will behave to a reasonable approximation, often to a *very* good approximation. However, eventually our predictive power will fade away, as microscopic structural effects (stress fractures, etc) start to cause major changes in the behaviour, for example.

    On the other hand, there are *plenty* of macroscopic systems that are *so* sensitive to their initial conditions that our predictive power is not very good at all - the first example I would give is the weather.

    The second example I would give is perhaps a little less intuitive but a nice illustration - the solar system. Many people think that using Newton's Laws we can predict the motion of the planets forever, but this is not the case - the solar system is in fact chaotic. But why then can we make such accurate predictions about planetary motion? The answer is that the time period over which our predictions become inaccurate is *very* long compared to say a human life span, and hence it seems like we have a stable predictable system but this is only because we are short lived compared to the solar system. Conversely we know weather patterns often change hourly and our hindered predictive power is more obvious.

    It's fairly amazing that we can predict the weather as far ahead as we can :smile:

    To get back to the brain, choice and so forth, I should say that opinion is divided. There is of course the school of thought that says free will is in illusion, for various reasons, but the underlying question from a physicists point of view is what kind of system the brain is. I am absolutely no expert in this area, so I won't put forth an opinion, but I have read arguments that the brain is strongly quantum mechanical (that is, the brain's behaviour cannot be analysed without QM), and I have read arguments that the brain is merely an immensely complex computer, whose behaviour *should* be able to be understood in terms of the behaviour of networks.

    I would guess the jury is still out. I believe Roger Penrose is in the 'QM brain' camp, he's written a book about it. (I'm not getting any points for referencing here, am I :blushing: )

    What I've written is way oversimplified, so I hope some more experienced physicists contribute, but I hope it helps.


    Kane O'Donnell
  4. Dec 31, 2004 #3
    Hisenburg procludes any chance for us to be able to percieve all the elements of a physical reality at once, in fact it procludes our ability to truly observe certain elements (like photons) without altering them, but it doesn't proclude the existence of those stable completely dynamic relationships. If the entirety of existence is regulated by a set of stable (not static) guidelines playing themselves out at the sub-atomic level, and those reactions are the result of over-lapping causal relationships, then our thoughts are the result of causal threads coallescing and diverging within our own heads, and our control of these relationships is just an illusion. And our thoughts which then cause our actions are simply the expressions of these dynamic equations playing out since the end of "early physics" at least. I know nOTHING about early physics so I can't apply this the first few moments of the universe. Sorry I had to bring this to you physics people, I know this isn't exactly physics, I'm not even sure what it is...
  5. Dec 31, 2004 #4
    Hi Kane

    Penrose is indeed a good person to reference in this discussion but the idea that determinism in terms of free will is somehow a mute point in terms of QM is plain rubbish. You can take Hameroffs microtubules or any other QM based theory of consciousness and there still remains serious and unsolved issues with regards to determinism versus free will.

    Its a "hard" problem and chalmers expressed it fairly well IMO. CI supporters like to pretend its not an issue, but they never come out with an explanation that makes sense nonetheless.

  6. Jan 1, 2005 #5

    Kane O'Donnell

    User Avatar
    Science Advisor

    If you say so :smile:

    Like I said, I really don't know enough about it, I was just airing some of the issues that would spring to my mind if I was asked to talk about determinism and quantum mechanics.


  7. Jan 1, 2005 #6
    As an engineer, you should ask youself this question:

    Do things stop obeying logical laws at different scales of reference? Or do they change from one form to the next as they move from one scale of reference to the next?

    On the issue of objects, observation, measurement and accuracy of results, you should ask yourself this question (which is logically equivalent to the first):

    Do things under observation and measurement turn into nothingness, stop being logical, lose their shapes, sizes and forms as they approach and extend beyond the 'CRTICAL OBSERVATION POINT (COP)', or what may be equivalently called 'CRITICAL MECHANICAL STATE' (CMS)?

    I can see the point of you being amazed by the question:


    Yes, the reduction of microscale reality to macroscale reality is a puzzle of an epic scale! But then, this in itself raises another serious question:


    For it seems that PERFECTION, properly defined, implies:


    As an engineer, instead of worrying about what physics does, you should be thinking of how to formulate new engineering principles that makes this to come to fruition. You should think of engineering principles and methodologies that allow the humans not only to structurally and functionally progress but, most improtanlty, to finally survive physical destruction.
    Last edited: Jan 1, 2005
  8. Jan 1, 2005 #7


    User Avatar
    Staff Emeritus
    Gold Member

    It isn't a puzzle of epic scale. It's simple mathematics. Hundreds of millions of probability functions that are all very close to 1 over an invisibly small region add up to produce a probability function for the macroscopic object made up by those hundreds of millions of particles that can only trivially be said to not be 1 within the region that we recognize as a visual boundary. Here's a simple example:

    Imagine a baseball made up of 3 billion atoms. Each atom is represented by a probability function that gives it a 1 in 1 billion chance of being within the structure we visually recognize as the baseball. That means that at any given time, 3 atoms will be outside of the baseball, and 2,999,999,997 atoms will be inside of the baseball. We cannot see the 3 atoms; we can only see the 2,999,999,997, so the baseball appears to be more or less spatially intact. When we zoom in, we can see that each atom has a pretty good chance of being within any region that is, let's say, 3 atoms wide. Utter chaos, right? It's like a baseball that cannot be said to exist anywhere except within a space the size of 3 baseballs. But because the space of 3 atoms is outside of our sensory grasp, we never recognize this chaos. We only recognize the extremely low probability that any atom will be far enough outside of its expected location to be outside of the baseball itself.
  9. Jan 2, 2005 #8
    Thanks for clearing that that up and, above all, thanks for the 'CERTAINTY'! I am glad, according to you, with simple mathematics, PROBABILITY continues to make things and events on logical pathways CRYSTAL CLEAR right after COP! And let's hope that this soon manifest into full explanation of everything under the current scope of the human visual capacity.
  10. Jan 2, 2005 #9
    I regard you more highly than the most of the people here as you are an engineer!

    I think the main issue here is whether we can find the answer or not. Civilisation may manage to emcompass the entire universe and consist of all matter and this civilisation would still be incapable of measuring to such a level of precision that it knows where everything is, what energy exists, where and when etc... Then again we may discover in the not too distant future that quantum seconds and quantum metres are the 'whole numbers' of the universe and that we can predict using a super computer the precise moment 2 particles collide and prove also that the universe is predictable (although perhaps impossible for the universe to become a conscious being capable of predicting itself).

    I would expect if we were the size of molecules we would also spend less time thinking more due to the reduced distances between the synapses in our brain and percieve the movements of these molecules as being as predictable as footballs. But if we were to attempt to measure how many metres multiplied by 10 to the power of minus 200 we would once again find ourselves with the same problem as we in our 1.8 metres high form have with molecules.

    If this is not the case, then it is possible to build a supercomputer capable of making these observations for us and the supercomputer could precisely calculate the movements of molecules in a heated bar of iron. In theory a supercomputer could be made to fire electrons at a regular and known rate at a bar of iron and calculate why it gets the responses it does, thus negating the restrictions of the heisenberg uncertainty principle. Could this be done do you think?
  11. Jan 31, 2005 #10
    Loseyourname said:
    It isn't a puzzle of epic scale. It's simple mathematics. Hundreds of millions of probability functions that are all very close to 1 over an invisibly small region add up to produce a probability function for the macroscopic object made up by those hundreds of millions of particles that can only trivially be said to not be 1 within the region that we recognize as a visual boundary. Here's a simple example:

    Extremely well said and exemplified---------- Photongod
  12. Mar 10, 2005 #11
    But why is it impossible? Because there are forces affecting the movement that we didn't factor in when we make our calculations, for an example the effect of distant stars or whatever.
    I can't grasp how it's not possible to predict the future accurately when you know all factors involved (whether that's possible or not doesn't matter, I am just hypothetically speaking). All movement in the universe is essentially just particles colliding with particles and forces affecting the speed and direction of those particles. If you could determine everything with infinite accuracy, you should be able to predict the future because all you have to do is to calculate how particles will interact with other particles.
    So how does something like free will and choice come into play when everything is predetermined, basically because the movement of particles can be calculated? For an example when an electron hits another electron it will be reflected in a specific way that can be calculated and won't go into a totally different direction just because it feels like it. I am aware of the uncertainty principle and that infinite accuracy is not possible, however that's not my point. Let's just say you have infinite knowledge about the state of a given system.
  13. Mar 11, 2005 #12
    "One might have hoped that this survey would provide an answer to the question: If we believe modern physics, is the world deterministic or not? But there is no simple and clean answer. The theories of modern physics paint many different and seemingly incommensurable pictures of the world; not only is there no unified theory of physics, there is not even agreement on the best route to getting one. And even within a particular theory -- say, QM or GTR -- there is no clear verdict. This is a reflection of the fact that determinism is bound up with some of the most important unresolved problems for these theories. While this linkage makes for frustration if one is in search of a quick and neat answer to the above questions, it also makes determinism an exciting topic for the philosophy of science."

  14. Mar 11, 2005 #13
    If you "want" a free will that is based on having some kind of immateial sould that
    pushes your physical body around, you are not going to get it.

    If you accept that you *are* the matter of your body, then the question
    "do I have FW" becomes "can my brain-body complex determine its actions
    in ways that are unpredictable in principle, yet not hoplessly capricious".
    QM gives you at least part of the answer, since it indicates that pretty much
    everyhting is unpredictable in principle.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook