1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Boltzmann Brain, and another question

  1. Oct 23, 2014 #1
    So I read this Boltzmann brain concept, and um yeah... So does this paradox imply that it is much more likely that I/you are a mind projecting an illusion universe in which we live as compared to a fine-tuned, and relatively low entropy universe in which there is many self-aware minds..?

    Also this got me thinking about something else.. Hopefully I can describe this thought adequately enough

    There are things (matter, energy) that are governed by rules (Gravity, electromagnetism etc..)

    Are these rules a consequence of the existence of these things?

    If they are--- then if there was a place devoid of all things, that is within this universe, would anything be possible within those confines?

    If they aren't--- if this same universe full of things somehow had all those things removed where are these rules actually residing? I understand that if we look at a simple system, like a game of monopoly for instance, the rules don't actually exist in the same context as the pieces, board, and the players.. but there is an enforcer of the rules that does exist if the game is to be played properly. (Not to imply that the enforcer would => be God)
  2. jcsd
  3. Oct 23, 2014 #2


    User Avatar
    2017 Award

    Staff: Mentor

    That depends on the structure of the universe, especially its long-term future and the completely open question if there are other universes with different physical constants.
    Define "consequence of".

    They work well in the best vacuum we can see or create, without any observed change.
  4. Oct 23, 2014 #3
    my meaning of the phrase "consequence of" is that with matter/energy comes these rules, and they are in some way connected, and inseparable.

    Forgive me this laymen question, and feel free to educate errors in interpretation..

    I realize that matter is being removed when creating a vacuum, but does creating a vacuum also remove the energy? Would a perfect vacuum be at 0 kelvin?
  5. Oct 23, 2014 #4


    User Avatar
    2017 Award

    Staff: Mentor

    That is not physics, that is philosophy (and therefore out of scope).

  6. Oct 23, 2014 #5
    I'm not trying to pose a philosophical question. Wouldn't the answer to this question have to be either yes, somewhat, or no definitively?

    what measuring stick are you using to divide philosophy and physics?
    Is it because at this time there is no known way of testing said question, or do you think said question could never be tested thus never reaching a definitive answer?
  7. Oct 24, 2014 #6


    User Avatar
    2017 Award

    Staff: Mentor

    The question is not even well-defined. There is no possible test that could give a meaningful answer to it.

    Physics cannot answer "why" or "how" questions on a fundamental level. Physics can provide a model that allows to make predictions about observations, but the question "is this model actually true" is not part of physics.
  8. Oct 24, 2014 #7
    I don't know if any of this is going to be helpful (because I know precious little about physics, I came on this board to try and learn more), but it got me thinking so I thought I'd write it down.

    My answer to the question, "Are these rules a consequence of the existence of these things?" is yes and no, or rather, both. The rules make the things and then the things make the rules in a constant cosmic dance of changes which is itself reality. I'll try and explain this (with what I think is an argument for the anthropic principle):

    Any reality must consist of things, that is distinct things. For these things to be they must be known, for something to be known it must be observed, and with any observation there must be a change because there must be a difference before the observation and afterwards, (otherwise no observation occurred). An observation is made to know something before the change that occurs because of that very observation, and in order to know what that change is another observation must be made, another observation, another change, and so on. It follows then that by knowing something there must be at least as many things that are unknown, indeed there must always be a quantity of that which cannot be known (otherwise called entropy).

    If there are distinct things, then some things must change more slowly than others, and from these differences in rates of change we can make up rules that predict how the things that change more quickly will behave relative to the things that change more slowly. Rules are by definition statements that do not change, therefore they can only ever approximate reality; they can never be proven to be true always and everywhere; for all of reality. This is consistent with the fact that there must always be that which cannot be known, indeed the absolute truth of all physical laws (or rules) is something that cannot be known.

    Nonetheless, as intelligent beings we have to make up rules otherwise we cannot know anything, and we are compelled by nature (reality) to know more and more as it is necessary for our survival, our continued being, a being that can observe and know. It follows then that the more we (and other possible intelligences) know, the more we make up rules, in order to know yet more still. With the more that is known, however, the more there is that cannot be known. Sorry, but that's reality! After all, the state where nothing can be known (e.g. maximum entropy heat death) is the same as one where everything is known. If you could know everything about everything, what it is, was and will be, then reality becomes utterly meaningless! It would seem as dead as the chaotic oblivion where nothing is known. Don't worry, for the reasons above, not everything can be known, and because it's impossible to come up with a set of rules that will explain everything because those rules would have to be able to prove their own truth, which is impossible (the Incompleteness Theorem). We'll keep on guessing though, and so we should!

    My answer to "if there was a place devoid of all things, that is within this universe, would anything be possible within those confines?" is anything's possible :p but probably not, as far as we know, though it depends what you mean by "those confines".

    As for the Boltzmann brain problem, my (perhaps naïve) answer to that is simply it doesn't matter. The question of whether or what we experience is "real" or just "a projection/fabrication" is immaterial since both the "real" (low entropy case) and "the projection" must necessarily contain the same information and therefore any such "projection" has as much of a claim on being a "true reality" as the "real" case. I think maybe Morpheus would disagree though...

    Hope this helps, or if you think I've said a lot of BS please let me know. You'd be doing me a favour ;)

    EDIT: By Morpheus I mean the guy from the Matrix, just in case there's someone on the forum actually called Morpheus - I'm afraid I don't know him.
  9. Oct 24, 2014 #8


    User Avatar
    2017 Award

    Staff: Mentor

    Sorry, that is philosophy, and we are in the wrong forum for endless philosophical questions where new answers are not possible even in principle.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Boltzmann Brain, and another question
  1. Another question (Replies: 1)