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B Begining of time, cause and effect and quantum randomness

  1. Mar 19, 2016 #1
    Hi Everyone.

    This thread relates to the ongoing debate as to whether or not time has a beginning and other related debates.

    As I see it, a beginning of time would imply the past existence of a very first cause which was not the effect of a previous cause. Who agrees and who disagrees with this implication?

    How well is cause and effect understood?

    It seems debatable as to whether or not quantum randomness truly exists but if it does then what are the implications of quantum randomness on cause and effect? For example, would quantum randomness mean that if the same initial conditions are repeatedly fed into a closed system influenced by quantum randomness then the same repeated outputs cannot be guaranteed?

    Could it be argued that any system influenced by quantum randomness cannot be described as a closed system?

    Could a first cause which was not the effect of a previous cause be the product of quantum randomness?

    Would a first cause which was not the effect of a previous cause violate any known principles of physics? (For example, any conservation principles.)

    How conclusively proven are the various conservation principles of physics?

    Thank you very much.

    Kind regards

    Tim
     
  2. jcsd
  3. Mar 20, 2016 #2

    jfizzix

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    I think the current models of physics are not prepared to answer questions about the beginning of time. The best I've heard of is that time had a beginning in the sense that you can't go farther north than the north pole.

    Cause and effect is understood on empirical evidence, as are all of our scientific models and conservation principles. The theories match the data as far as we can tell. That doesn't mean violations of causality or of a conservation law are logically impossible, but none have ever been observed, and a rational person with the evidence they have would bet against it.

    Conservation laws are a bit more fundamental than a particular physical theory, in that they rely on the theory being independent of absolute coordinates. Since the laws of physics appear to depend on relative and not absolute position, we get conservation of momentum. Since they depend on relative time, we get conservation of energy. Since they depend on relative orientation, we get conservation of angular momentum. It's worth pointing out that when these symmetries are not held, the corresponding conservation laws don't need to either. For example, in General relativity, the warping of spacetime means that these conservation laws are not absolute, but depend on the neighborhood of spacetime you're in. Except in extreme scales, spacetime is flat enough that we can take these conservation laws for granted.

    There are indeed different schools of thought on whether quantum mechanics is fundamentally random. What everyone agrees on is that experimental results of measurements are impossible to predict with 100 percent accuracy unless the system is prepared in the state that's already the outcome of your measurement. Otherwise, it will be unpredictable (though you could give probabilities). What this means for the initial conditions for the universe is highly speculative, but it wouldn't be out of the question to say that the current large scale structure of the universe was due to quantum fluctuations in gravity very shortly after the big bang.

    A quantum system is "closed" if it is completely isolated from everything else. In that case, the quantum state evolves deterministically according to the Schrodinger equation describing it. When you measure a quantum system, that measurement is an interaction with that system. it is a physical process whereby information about that system gets transferred to another object. This process changes the state of the system in an unpredictable way. In that sense, you could say that any system influenced by quantum randomness cannot be considered closed because random jumps in state like that can only be due to a measurement or other interaction. It's worth pointing out, that the system is at all times described by quantum mechanics, and in that sense, is always governed by quantum randomness.

    In order to get a conclusive answer to questions like these, we would need a theory of physics that agrees with both quantum mechanics and general relativity (i.e., a quantum theory of gravity). Currently, all we can do is speculate.
     
    Last edited: Mar 20, 2016
  4. Mar 20, 2016 #3
    I too find that most (if not all) discussion of Prime Mover and such are not so much borne out of a legitimate inquiry, but most people's inability to think of scenarios that are not embedded in time. Both the word "before" and "causality" imply an ordering along the time line, and thus already are ineligible wordings when considering the edge of time.
     
  5. Mar 20, 2016 #4
    Hi Jfizzix and Rumborak

    Thank you both very much for your replies

    To be honest, I find this a bit difficult to get my head around because it suggests a reversal of past and future. However, I suppose it fits in with the idea of spacetime as an unchanging four-dimensional block. which is carved by pure mathematics. But that would not explain how our consciousnesses experience the universe.

    If science is a democratic and humble pursuit, I can't see how any inquiry can be considered illegitimate until it is proven to be so.

    Kind regards

    Tim
     
  6. Mar 20, 2016 #5
    "Illegitimate" may have been a too-connotated word. What I mean is that asking what was "before" time or what "causes" the universe, you are essentially asking "what is 3 plus green?". It's "illegitimate" in that sense.
     
  7. Mar 20, 2016 #6
    Hi Rumborak

    I am not querying what was before time. I am querying whether or not it has a beginning. I agree that it does not make sense to ask what was before time. If time does not have a beginning or end then asking what was before or after it would be like asking what is beyond infinity. I am not doing this.

    Kind regards

    Tim
     
  8. Mar 20, 2016 #7

    Nugatory

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    None of the questions being asked here have much to do with physics, so this forum is a poor home for the thread and it is closed.

    As always, if you have a contribution to this thread that is connected to the current understanding of science, you may PM a mentor and ask that it be reopened.
     
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