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Why can't physical laws be broken?

  1. Sep 9, 2005 #1
    Many people like to say that certain phenomena cannot happen because of the laws of physics. Letting aside the issue of whether some phenomena are really impossible for whatever reason, I'd like to investigate the basis for the notion of immutable, absolute laws. There are three things I don't understand:

    1 - What reasons are there to think the universe is ruled by absolute laws?
    2 - What reasons are there to think those laws do not leave room for exceptions?
    3 - Above all, what reasons do we have to think we know what those rules are?

    It seems to me the notion of "laws of the universe" is merely a belief. Like all beliefs, it has some supporting evidence, but also like all beliefs, it lacks rational justification. That is how I see it anyway.

    Any comments?
  2. jcsd
  3. Sep 9, 2005 #2


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    I don't see how one can say that they don't have rational justification. Justification to me is "does this work everytime as far as anyoen can tell". Good enough rational justification for me!

    I also think we don't believe there are exceptions because we haven't found any (and when we have in the past, it just turned out to be ignorance and was corrected).
  4. Sep 9, 2005 #3


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    There is justification, it is just an ad hoc justification. And the sounder the justification gets, the less appealing the notion of absolute laws becomes. Basically, we can say that there are absolute laws, and they are probably like what we think they are. If we ever observe an exception to something we hold to be a law, we realize that it is not that there is an exception to the law, but simply that the actual law is different from what we thought it was. Anything that happens, we can look at and then say that whatever reasons that specific event happened are physical laws, and then we attempt to find those reasons. The reason this loses appeal is that we are saying that there may be a specific law for each and every single unique event. At this piont, it might not even make sense to call them laws, or at least, it wouldn't be interesting. We are only interested in physical laws because they appear to be general.

    So we start with the assumption that things happen for a "reason". "Reason" might not be the right word, but hopefully you know what I mean. Why is this a good assumption? Well, denying it would mean that every time the equation F = ma makes a good prediction, it is pure luck. We don't have absolute justification for this assumption, but we have sufficient justification.
    We then tend to observe that certain reasons are generalizable and can explain a variety of phenomena.
    We take our observations and try to make generalized laws, then test our laws to see if they really do hold in general.
    If we find exceptions, we correct our laws. Suppose a certain law appears to break down when the speed is near c. Then we correct our law so that it looks the same when the speed is very low, but alter it so that it changes enough to match the observations when the speed is near c.
    It's probably safest to say not that we know the rules, but we hypothesize about what the rules may be and continually test our hypotheses in a variety of situations to check that the rules we hold are the general rules governing physical bodies. We can't try every possible situation, so we can't be 100% certain, but no one says we are, and no one needs to be that certain.
  5. Sep 10, 2005 #4
    Exactly! We invent laws to account for what we ultimately don't understand. Anything that happens can be accounted by laws, but it doesn't mean the current laws prevent the occurrence of specific phenomena. If the phenomena do occur, then we have to change the laws, not deny the occurrence.

    It is not luck, it's cleverness. The laws of physics are created in a way that makes them difficult to be falsified. But that doesn't mean they tell us what can or cannot happen; it only means most known phenomena can be accounted for by existing laws because that is what the laws were made for in the first place.

    From another perspective, to claim something cannot happen because the laws of physics prevent it is equivalent to claiming one understands all laws of physics in their entirety, including laws yet to be discovered. That is what I find an extremely irrational claim -- no one is that smart.

    So why do people often say "that cannot happen because it violates the laws of physics"?
  6. Sep 10, 2005 #5


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    That's my point. Denying the assumption that things happen for some "reason" would mean that F = ma is just a lucky guess, but as you say, it's not luck.
    This is wrong, to a degree. Scientific laws are not just clever tricks that are hard to falsify. What makes them hard to falsify? They are very easy to falsify, theoretically. If a law is correct (i.e. if the law we believe is an actual law of physics) then it will obviously be impossible to prove false, but that's not what we mean when we talk about "falsifiable." Of course, we don't demand that all of our laws are false - those that are true cannot be shown false. But there must be a method that could be used to show it is false if it really were. A cleverly worded hypothesis might be impossible to falsify, even in theory. However, F = ma can be falsified. Measure the mass and acceleration of an object as you apply a force to it. If the equation doesn't work, then either account for the hidden force, or accept that the law is wrong. If we can prove that there are no hidden forces (and I believe things like this aren't impossible to prove, Bell supposedly proved something like this with respect to local causes of random quantum events) then we have falsified F = ma. So it's not just "cleverness".

    If we propose F = ma because we notice things in our labs work that way, and then we find that when we observe stars millions of miles away, they behave in accordance with the very same equation, then the equation is not just clever wording, it is a good general prediction of physical phenomena. And although our physical laws cannot tell us with absolute certainty whether something will happen or can't happen, it is very reasonable to make predictions based on scientific laws than based on nothing, as though scientific laws give us no better understanding than if there were nothing.

    Science does not give us certainty, but we do use scientific laws to predict physical phenomena every day. If F = ma were just a clever guess, and weren't really a reliable tool for prediction, then engineers couldn't do all the things they do today safely. The science of electronic circuits allows us to design and build computers. If those laws confered no power to predict on us, then we would be no worse of just randomly soldering chips together. But we don't. We can look at the laws and principles, design on paper a chip whose behaviour and efficiency we can predict, and then proceed to build it.
    Because if people were to prepend every claim with "Although there is the possibility that things will be otherwise, it is very reasonalbe to believe that..." it would get annoying. If someone says something like "this cannot happen because of the laws of physics" and you decide to be the pedant and say, "ah, but there's a chance that the laws we think are right, are actually wrong," most people do indeed realize this and will say something like, "yeah, yeah, of course they may be wrong, but you're just being pedantic... I'll trust scientific claims about gravity and human biology and won't jump off this cliff, but go ahead and do it if you think anyone should bother considering the slight chance that the laws are wrong and you'll be able to fly once you jump off." There is of course the possibility that laws are wrong, but this possibility is irrelevant in everyday conversation. This doesn't mean people deny the possibility, they just don't waste time considering it every step of the wa
  7. Sep 10, 2005 #6
    its all about fundamentals...if you have fundamentals then there are certain things that don't exist in the vector spaces in which these fundamentals lie.

    its like living in 3D space..you can not explore 4D because you only have 3Ddimesnsions...however if you live in 4D space you can explore 3D space.

    good old graphics theory.

    as pertaining to the universe and physics/TOE...we odn't really know whats fundamental...we can only hazard guesses SO

    that statement should be said
    "that cannot happen because it violates the CURRENT laws of physics
  8. Sep 12, 2005 #7
    To belief that nature is complex, uncomperhensible, and full of exceptions would simply destroy the whole academic enterprise. In other to have any system of worthy questions, there must exist in the system a set of axiom that must not be challenged. If the first axiom of physic is that physical law exist, then the second axiom would be that all physical phenonmen can be reduced it is elementary component, and that the underlying reason is simply. It is a philosophy. See!
  9. Sep 12, 2005 #8
    I think that humans need to fall back on 'absolutes' because we simply can not comprehend our existance if we did not believe such things. However, let me ask you this:

    What reason is there to believe the universe is not made of absolute laws?
  10. Sep 13, 2005 #9
    I'm not talking about beliefs, I'm talking about the reality of some phenomena. Some people claim they know reality is absolutely incapable of producing some phenomena. My question is, how do they know?
  11. Sep 13, 2005 #10


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    Two ways: No experiment (out of thousands over a century or more) ever shows the contrary, and using the law to derive other effects has always generated effects that agree with physical measurements. So a physical law, no more than any other physical theory is not "proved" in the sense of logic or mathematics, but is supported by a tremendous, interacting body of evidence that is very tough against attempts to contradict it. As science develops, old laws that had a run of centuries get restricted to a subset of physics, for example "Newton's laws of motion".
  12. Sep 13, 2005 #11
    1. To say "there are no absolutes"--is itself an "absolute" statement, therefore, if you hold "there are no absolutes", in fact you hold that absolutes are possible.

    2. As to the question--"how can one "know" that "reality" is "absolutely" incapable of producing some "phenomena"--it is critical that one understand the definitions assumed for the words in "--". I would like to consider the opposite statement: "how can one know that reality is absolutely capable of producing some phenomena" ?

    3. To help answer this question, I would like to point out that the Objectivist philosophy of Ayn Rand recognizes two different types of absolutes, "out-of-context absolutes" and "contextual absolute". Out-of-context absolute statements always involve a contradiction in terms, while contextual absolutes represent an immutable truth held within a specified context. According to Rand, those that follow the thinking of Kant mistakenly hold that absolutism is incompatible with a contextual approach to knowledge--such folks define an absolute as being independent from cognition--which then requires that absolutes must derive from revelation. But, for Rand, this is false thinking, absolutes can only derive from the evidence of the senses.
    As stated by Rand "the metaphysically given is absolute".

    How can I know that this statement by Rand is absolutely true" ? I would suggest that I "know" this statement to be true the same way know anything to be true, because I know that I "exist" as a metaphysical given, thus I know that "I" am an absolute.

    In the end, for me, in comes down to the critical importance of "definition", and how such definitions differ from the "concepts" (such as "absolute") they attempt to define. Rand, for example, has no problem with the concept of absolutes because of the way her metaphysics matches logically with her epistomology (e.g., knowledge of absolutes). Of course Rand may not be correct, and either (1) there are no absolutes, or (2) absolutes are derived from revelation. Rand offers the logical third option--absolutes derive from the evidence of the senses, and thus must always be contextual in order to be absolute.
  13. Oct 13, 2005 #12
    Just a quick comment I'd like to add that you can't break (or dismantle) the universal laws of physics because there is a law that governs any broken universal law. In other words there is a safety net of universal laws that cover what happens when other universal laws are broken.

    In fact there is more than a probability of a "universal law" demonstrating that when you do break one of the universal laws you will experience the consequences of doing so. The consequences are often in the form of another universal law.

  14. Oct 14, 2005 #13
    More importantly, a very universal description of a physical law is "balance".

    When balance is lost in the universe this creates a temporary state of imbalance, where ever it happens. Then, other physical laws go into action to restore the physical laws of balance.

    This is my relative view of the physical law of balance. I'm probably wrong about there ever being any imbalance in the universe. There are, perhaps, simply extreme conditions that appear unbalanced which are, in a universal reality, demonstrations of a universe maintaining its balance. What a place!
  15. Oct 15, 2005 #14
    And this is exactly how science proceeds. For example, if you come up with any reproducible experimental evidence that shows the law of gravity to be false, we would then have to review the law of gravity.
    I don't see your problem?
    I disagree. They are created in order to comply with what we actually observe in the real world, ergo they conform to reality, ergo they are not easy to falsify. A law that is in practice easily falsified is hardly a law that will last very long!
    yes....... but so what?
    It would be more correct to say that "something cannot happen because it goes against the existing known laws of physics" - but that does not preclude new laws of physics, and therefore does not prevent something from happening per se.
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