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

Would laws be different?

  1. Aug 16, 2006 #1
    Would laws be different if the big bang happened a different way? Like, if the big bang happened again would gravity, particles, and anything be different in physics?
     
  2. jcsd
  3. Aug 16, 2006 #2

    DaveC426913

    User Avatar
    Gold Member

    Yes. In fact, this is a great big-ass deal in Cosmology (if not THE big-ass deal).

    The universe is considered to be "exquisitely tuned" for life as we know it.

    There are a number of fundamental constants about our universe that, if any one of which were evenly slightly different, the universe would have developed so differently as to be incompatible not merely with life, but with matter (i.e. atoms).

    How our universe has managed to come into existence in its current configuration instead of any of countless other configurations is a question that keeps Cosmologists and Theologists awake at night.
     
    Last edited: Aug 16, 2006
  4. Aug 16, 2006 #3

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  5. Aug 16, 2006 #4
    I am new to the list. Not a scientist in any manner, just an artist w/ great curiosity. Forgive me if I trip over my own ignorance. It seems that the"'exquisitely tuned' for life" idea suggests the anthropic principle. From reading some of the postings, I suspect that Leonard Susskind is not one of the favored gurus, but he does write convincingly regarding the A/P. While I am reluctant to pose such a broad question, I wonder what the current thoughts are regarding the A/P.

    Ben Mahmoud
    http://benmahmoud.com
     
  6. Aug 16, 2006 #5

    Weak or strong?

    The weak anthropic principle is tautology. Of course we see conditions that permit life, since there is life in the universe, so conditions in the universe permit life. The strong anthropic principle is theology, not science.
     
  7. Aug 16, 2006 #6

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    But the question is the extent to which this is an explanation of what we observe. That it's true is uncontroversial. That it's relevant is not.
     
  8. Aug 16, 2006 #7

    I don't see that it can be used as an explanation of anything--unless one accepts the strong anthropic principle as well.

    Using the statement 'we observe conditions that permit life because we are alive' as an explanation for why the conditions of the universe permit life confuses cause and effect.
     
  9. Aug 16, 2006 #8

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Suppose there were N self-contained "universes", only one of which could support life. What is the answer to the question, "Why do the conditions of my universe permit life?" Certainly I can correctly say that if they didn't, I wouldn't be around to ask. Granted, that's not a complete answer, because I can go on and ask, "why do the conditions of any universe permit life?", but in this hypothetical case, it tells us something, it tells us why we don't live in one of the N-1 other "universes".

    The point is that our observations of the universe might be biased by our very existence. If the above hypothetical case were true, it would be foolish of me to attempt a theory of universe formation that always led to conditions that support life. On the other hand, it's possible that all N self-contained universe can support life. Then, there is no bias and our theories would want to make a concerted effort to explain the parameters of our universe from something more fundamental. This latter case is preferred by scientists because it means that there is more information in our own universe -- studying it will tell us more about how the universe came to be. In fact, many scientists would say that we should always disregard the anthropic principle because it amounts to "giving up". The more biased our surroundings, the less point there is in studying them.
     
  10. Aug 16, 2006 #9
    This of course, supposes that there are other universes--a by definition untestable proposition.


    I would argue that the anthropic principle is a waste of time because it provides nothing of scientific value--except the recognition that the fundamental configuration of the universe that we see, may not be the only possible one. But it does not explain anything.
     
  11. Aug 16, 2006 #10

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The argument doesn't require the existence of other universes, only the possibility of existence given what we know.


    How does it provide the "recognition that the fundamental configuration of the universe that we see, may not be the only possible one"? Why is this recognition not possible without the anthropic principle? Why does the issue of bias not arise if there is only one universe? What do you mean by "it does not explain anything"? Is that merely a semantic objection or do you believe that there are no logical connections between our existence and the parameters of our universe?
     
  12. Aug 16, 2006 #11
    I think, my objection may be largely semantic--it depends on the nature of the logical connection you are suggesting--the cause and effect nature specifically. This is something that I am not clear on, and various explanations of the principle suggest differently. Some seem to suggest that our existence causes the parameters of our universe to take the values they do--this is what I am rejecting.
     
  13. Aug 16, 2006 #12

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    This is a bad argument, IMO. Forcing the laws of the universe to permit our existence is unnecessary and confusing. Obviously, we would not otherwise be here to ask that question. How astonishing is that? I agree to the extent a universe that forbids our existence is illogical. I do not see that it demands our existence.
     
    Last edited: Aug 16, 2006
  14. Aug 17, 2006 #13

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I agree with you about the strong anthropic principle -- it is basically a religious statement. I also agree with you that our existence did not cause the universe. However, I stand by my use of the word "explanation". The anthropic principle does not explain why the universe came about in the way it did, but it does tell us why we observe what we do. The latter question is the one the scientific method is directly addressing, though the former is the one we would really like to answer.

    If a certain characteristic of the universe is required for us to exist, then our observation of that characteristic tells us nothing. Without being able to observe other universes (or other iterations of our own), the anthropic principle may be the only viable explanation for that observation.
     
  15. Aug 17, 2006 #14
    Ive got a question, if atoms changed, would all subatomic particles change too? If so, why and how would they change?
     
  16. Aug 17, 2006 #15
    Okay, then I misunderstood what you you were claiming it explained.

    I think I agree with what you are saying--assuming that I understand you correctly--but I think that the wording is horrific. Much better to say that the explanation is simply 'we can only observe universes that allow us to exist' (again, tautology), than the way it is normally posited.
     
  17. Aug 17, 2006 #16

    SpaceTiger

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    That's rather terse. I wouldn't expect a non-scientist to fully appreciate the consequences of that statement without further explanation.
     
  18. Aug 17, 2006 #17

    Further explanation is okay. But the presentation/wording I've normally seen is horrifically confusing and unclear. Saying that we observe conditions that permit life because we are alive, could mean two very different things, depending on whether the 'because' is causal or not. This distinction is not sufficiently clear. If the because is not causal, then its ok. If the because is causal, then I think there are some issues.
     
  19. Aug 17, 2006 #18
    Ive got a question, if atoms changed, would all subatomic particles change too? If so, why and how would they change?

    Anybody home?
     
  20. Aug 18, 2006 #19

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    Assumes facts not in evidence. You need a theory that explains why atoms would change before discussing how they would change. That's a cowpie in my opinion, fedorfan.
     
  21. Aug 20, 2006 #20
    Alright, if the big bang happened a different way, would the atomic model as we know it change? If so why and how, if it did, would subatomic particles change(protons, neutrons, quarks, electrons, neutrinoes,etc)? If so, how and why?
    thanks
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Would laws be different?
  1. What would happen (Replies: 3)

Loading...