# Could a finite time universe exist "eternally"?

In a world of one spatial dimension and one time dimension, we can, as physicists working on relativity do, consider world lines in space-time. That is, consider the xt-plane with t as the horizontal axis and x as the vertical axis. If there exist, for instance, three points in the universe, the entire world history can be represented as curves in the xt plane. These are the world lines of each particle.

I suppose we could have a cut-off on the time axis such that the space time world does not exist for t < 0. That is, space time is only the right half plane. What if actual space time was a static entity, as if a sphere in three dimensions eternally fixed, as a four dimensional object? This suggests that the universe could "come from nothing" in the sense that there is a time boundary. But this also seems that one can back up and take the whole picture in and just say the universe exists even though it has a "beginning" from a time perspective. In this situation we say that the universe does not have a cause. Our difficulty with all this is that we exist temporally and cannot put ourselves in the greater perspective required.

Are there any defeaters for this possible belief? My impression is that most cosmologists believe there must be a cause for a universe, and perhaps many philosophers think the same, but I don't understand why they do.

• I dispute this question being tagged as philosophy of science. Whether or not the universe exists eternally has philosophical significance that goes way beyond science. For instance, there are possible theological implications. Commented May 15, 2014 at 3:06
• "What if actual space time was a static entity, as if a sphere in three dimensions eternally fixed, as a four dimensional object?" This idea is called the block universe. Consider it in one dimension. We have, say, a function f defined by f(x) = x^2. We may regard this as describing the path of a ball tracing out a parabola in the plane. Or we may regard the parabola as sitting there eternally. No motion is necessary, all points exist at once. You could do the same thing with the universe. If you plot the state of the universe against time, the graph for all t is a static object. Commented May 15, 2014 at 4:41
• @user4894 Great! I didn't know that term. That's exactly what I'm wondering about. Are there defeaters against holding such a view of the world, specifically with the idea of a beginning to time? Commented May 15, 2014 at 4:44
• Not sure of the precise meaning of the term "defeaters." But as far as the block universe, who's to say? The entire universe is just a static pattern engraved on a rock in a much larger universe. A rock that became aware of itself. Who's to say no? Or yes? It's not knowable. [Meta: When I start with "@nayrb" it gets ignored. Is this a bug at my end? Am I doing it wrong? Not just you, but this happens with everyone, but not all the time.] Commented May 15, 2014 at 4:47

Finite is the opposite of infinite. The same as eternal being the opposite ephemeral.

So if we are to hold the law of non contradiction to be true then two opposites would (Or could) then not be true at the same time. Wikipedia would define the law as the following.

In classical logic, the law of non-contradiction (LNC) (or the law of contradiction (PM) or the principle of non-contradiction (PNC), or the principle of contradiction) is the second of the three classic laws of thought. It states that contradictory statements cannot both be true in the same sense at the same time, e.g. the two propositions "A is B" and "A is not B" are mutually exclusive.

Are there any defeaters for this possible belief? My impression is that most cosmologists believe there must be a cause for a universe, and perhaps many philosophers think the same, but I don't understand why they do.

Well this is a rather large area of inquiry spending thousands of years. I will try and give a short history of some of the more broader schools of thought in regards to causality.

PLATO Though the ideas of causation has emerged in Pre Socratic philosophy, it was Plato who first stated the principle of causality: "every­thing that becomes or changes must do so owing to some cause; for nothing can come to be without a cause" (Timaeus 28a).

...and has no Becoming? And what is that which is Becoming always and never is Existent? Now the one of these is apprehensible by thought with the aid of reasoning, since it is ever uniformly existent; whereas the other is an object of opinion with the aid of unreasoning sensation, since it becomes and perishes and is never really existent. Again, everything which becomes must of necessity become owing to some Cause; for without a cause it is impossible for anything to attain becoming. But when the artificer of any object, in forming its shape and quality, keeps his gaze fixed on that which is uniform, using a model of this kind, that object, executed in this way, must of necessity

ARISTOTLE: FOUR TYPES OF EXPLANATION.

You could say that Aristotle was the first to make a full fledge critical account of the matter. In essence Aristotle claimed that when we ask "What is this?" We could answer the question in four ways. Each answer pertaining to a quality of the cause. (aitia)

The material cause: - that out of which The formal cause: - the form”, “the account of what-it-is-to-be The efficient cause: - the primary source of the change or rest The final cause: - the end, that for the sake of which a thing is done

THE STOICS AND CAUSATION.

The stoics injected the cosmos with a logos (Divine Cause) that was ordain by the concept of fate. The stoics where firm believers in the necessity of causes to events. Which was key to there view of the coherence of the universe. Universal Causation

CAUSATION IN THE MIDDLE AGES:

Here a view contrary to Aristotle emerged. Two different views on Efficient causes which was a radical turn on the Aristotelian view,

Primary Cause: Something which is generated in of itself. Secondary Cause: All material has been created by God and has certain intrinsic property.

THOMAS AQUINAS

Aquinas' posit five ways to argue the existence of God. His fifth way concludes from the observation of finality within natural bodies that there must be some intelligent being, God, by which all natural things are ordered to their end.

CAUSATION IN MODERN PHILOSOPHY

1. Descartes: dismissal of forms
2. Hobbes: causation and motion
3. Spinoza: causation as necessitation
4. Leibniz: sufficient reason
• I used quotes for "eternal". I clearly don't have an english word for the property I am trying to describe and I don't literally mean eternal. I am trying to describe a situation where the universe has a finite age but no cause. Commented May 15, 2014 at 16:24
• I added some more meat to my post in regards to your comment. Commented May 15, 2014 at 17:16
• I'll add more tomorrow. I need some sleep now. Commented May 15, 2014 at 18:15

See St. Thomas Aquinas's opusculum (short work) De Æternitate Mundi (On the Eternity of the World), in which he shows that even if "the world had a beginning in time," "The question still arises whether the world could have always existed".

If one holds the premise that time is singular, immutable, and linear, then one is left with two mutually exclusive possibilities:

1) The universe had a beginning and will have an end. Therefore, the universe exists in a finite timeframe. Thus, time is measurable.

2) The universe had no beginning and/or will not have an end. Therefore, the universe exists in an infinite timeframe. Thus, time is not measurable.

Given possibility 1, our concept of being able to measure time as "the difference between two dissimilar events" holds true. Given possibility 2, however, this concept is false - either all times exist simultaneously or no time exists at all. For it doesn't matter how many times you subdivide infinity; you still end up with infinite immeasurable parts.

The mere fact we seem to exist in our "own time" suggests that possibility 1 must be true. The alternative is that time itself is an illusion.

If one accepts the "big bang" and expansion as plausible, then one might consider the hypothesized "big bounce" continuation, whereby this (hypothesized) finite and expanding universe, will reach peak expansion and contract upon itself, until it returns to the original state and then begins again.

This would add an "eternal" characteristic/property to a re-occurring finitely lasting emergent and re-emergent universe (and re-emergent, and re-emergent, and....)

Eternally re-occurring finite duration universes.

IF one accepts the current hypothesized "big bang" and "expansion". I find them to be dubious claims, logically.

https://en.wikipedia.org/wiki/Cyclic_model