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

The Infinite Universe Expands is Inaccurate

  1. Sep 5, 2004 #1
    The term "the universe is infinite" is inaccurate considering the fact that the universe is expanding.

    1.)By definition, an "infinite set" is: a set whose cardinal elements are equal to the subset of the [infinite] set.

    2.) By definition, the word "universe" is defined as "all that there is".

    3.) By definition, "space" is the set containing all points. Thus interchangeable with "universe".

    4.) By definition, "expand" is "To become greater in size, volume, quantity, or scope"

    If the universe becomes greater in size, then it is increasing the space which constitutes itself [the universe]. But can something infinite increase its size? I am pretty sure that it cannot; I am open to correction.
    Therefore, (assuming my aforementioned conclusion is correct) saying that "the universe is expanding" is illogical. Rather, "a finite subset of the universe is diffusing itself into the set containing the finite subset."

    Of course, that would be assuming that space does not neccesarily depend on occupying matter to exist, right? My reasoning is this:
    The universe is a set containing space which is the set of all points (thus including all of the cardinal elements of the universe) that if only the contents of the universe are expanding, then the entire universe should be too unless not all of space is expanding or only the occupied space is expanding.

    Another idea I have for this problem is this: If the universe is infinite and is expanding, this means that the way the contents of the universe are arranged is changing?

    Wait, I just got an idea (or rather a question): The universe cannot be infinite because it would converge to a limit, as in calculus, right?

    If my ideas are incoherent, please point that out so that I may try to clarify it. I just jotted this down because it has been on my mind for the past week, and I wanted your opinion on it. Thanks.
  2. jcsd
  3. Sep 5, 2004 #2


    User Avatar
    Science Advisor
    Gold Member

    This is incorrect, genral relativety allows for an infiinte expandoing unievrse without contradiction.

    1.)By definition, an "infinite set" is: a set whose cardinal elements are equal to the subset of the [infinite] set.[/quote]

    By defintion an infinite set is set that has a one-to-one correspondance with a proper subset of it's self i.e. a set containing a proper subset of the sam ecardianlity as itself.

    The universe is usually defined as evrything.

    space is poorly defined, infact you have to be careful, the set of which points? the set of points in a given observers frame at a given time or the set of events in spacetime?

    Not necessarily: in this context to expand means that the distance between two objects, will generally becpome greater with time.

    No tan infite universe doe snot increase in size

    see above.

    basically yes.

    No the universe is not an inifte sequence, series, etc.
  4. Sep 5, 2004 #3
    What is the difference between my definition and yours?


    Yes, the distance expands not neccesarily the object. The definition can refer to distance as well as the object.

    Please explain.

    What is the universe expanding into?

    How is this determined? Why is it so?

    Thank you.
  5. Sep 6, 2004 #4


    User Avatar

    Staff: Mentor

    Well obviously, since the universe is "all that there is" it isn't expanding "into" anything. Its just expanding.
  6. Sep 7, 2004 #5
    Right! Expansion can be intrinsic as well as extrinsic. This reminds me of how some people wrongly insist that if an n-space is curved, it must be curved in a n+1 space. Of course, both expansion and curvature may be either intrinsic or extinsic.
  7. Sep 8, 2004 #6
    The term "Big Bang Theory" is often the source of a misconception that results in this question. "Big Bang" is conceptually viewed as an explosion that takes place, and any explosion that we observe here on Earth expands into "something," i.e. the surrounding air, water, etc.

    This is what is observed and explained via "Inflation Theory," which I think is a better name for the theory which describes what is happening to the universe.
  8. Sep 8, 2004 #7
    With regards to this, there are several fundamental issues that Physics is not paying enough attention to.


    The assumptions manifesting from the BIG BANG thesis, true as some of them may seem, do not allow physic to pay much attention to the notion of time scale (that is, a time frame within which a given event starts and completes a single cycle of its fucntion) relative to the observer. The problem that is being fundamentally ignored is that time scales come in various degrees and sizes and many of them are beyond the human visual frames of reference. Relative to the human visual frame of reference, there are mixtures of macro and micro time scales that extend beyond the human observational range. Even with microscopic and macroscopic scientific instruments, we still cannot gain sufficient access the exact contents of these time scales. For example, it is almost absurd to claim that things and events contained in infinitely brief time scales are commencing and continuing. It is worst still to begin to say that, at the cosmological time scale, a cosmological event or object that takes billions of earth-years to complete a single cycle of its function is commencing and continuing. What right have we to lay claims to the knowledge of an infinitely exapanding universe when we do not know the exact time scale of such an event?


    If the universe is structurally and functionally co-referential, how would we know this? For all we know, the universe may be one amongst many! There is nothing as of yet which writes off this very possibility. Even physics itself does not rule out this either.


    I always take Einstein's remarks that 'God does not play dice with the universe' to imply that the ordering of things in the unversde, though outwardly chaotic in appearance, is fundamentally progressive, both in scope and in substance. If this is true, how does this fair with the notion of an infinitely expanding universe? Is infinite expansion progressive?


    Aspects of the big bang theory seem to suggest that the universe may be structurally and functionally going around in circles....that is, big bangs after big bangs, ad infinituum. The concept of circularism is well-hated in philosophy and I would think that people in the science community would be feeling the same way about it. How does the notion of Circularism fair with the Notion of Structural and functional progress of the universe, if any? Is Circularism progressive, or is it perfection itself?
    Last edited: Sep 8, 2004
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: The Infinite Universe Expands is Inaccurate
  1. Expanding universe (Replies: 2)