Ethan Siegel has an excellent post up contemplating the various models of the timeline of the universe.
It’s only human to ask the most fundamental of all questions: where did all this come from? And we like to think we know the answer; it all came from the beginning.
But if you think about it for a little while, that simplistic answer — an answer that at first glance, might appear to be a tautology — presumes something very important about our Universe: that it had a beginning!
For a long time, scientifically, it didn’t appear that we knew whether that was true or not. The Universe could have had a beginning, before which nothing existed (or, at the very least, nothing as we understand it to be), or it could have existed eternally, like an infinite line extending in both directions, or it could have been cyclic like the circumference of a circle, repeating over and over again infinitely.
via How did the Universe begin? — Starts With A Bang! — Medium.
One thing I’ve noticed about this is that, at least in the last century or so, theoretical physics seems to have had a strong prejudice for the infinite universe.
It was Einstein’s preferred model, so much so that he introduced the cosmological constant to avoid dealing with the otherwise mathematical need to explain either an expanding or contracting universe. He later referred to that move as his greatest blunder. (Even though it ultimately proved prescient with dark energy, but for the wrong reasons.)
Once it became apparent that we were in an expanding universe, Fred Hoyle introduced the steady state theory to explain away any possibility of a beginning. His theory remained a respectful alternative to the big bang until the discovery of the cosmic microwave background, a prediction unique to the big bang. But Hoyle never accepted defeat, holding on to steady state until the end.
Shortly after a need for cosmic inflation was realized, eternal inflation became a popular assumption. Even if eternal inflation ultimately ends up not being accurate, and our universe appears to have a beginning, there will be the various multiverses theories to make the whole works timeless and eternal again.
Whenever theoretical physics has little or no observational information, it seems to default to reality being timeless and eternal. To a large extent, I can understand this, since timeless infinity is mathematically simpler than a finite or circular timeline.
But since observational data is generally assessed within the framework of theoretical assumptions, it seems like this should make the physics community a bit uneasy, a bit on guard that this preference could blind them for a while to contrary empirical evidence or even mathematical implications. I see posts like this one from Siegel as a good sign that there are physicists resisting this temptation, but I it seems like I read a lot more from others assuming infinity.
SelfAwarePatterns 
(sap) can jump to another topic… If so, the only way that we could ever falsify that theory would be to discover aspects of the universe that are not mathematical. Of course, we could never eliminate the doubt that it’s simply an aspect we don’t understand the mathematics for yet – very interesting insights that would have been even more significant if you wanted to expand it a little more. of course, just a little because i understand this is a very deep subject for thought.
(dm) i think it also contains some doubts that you didn’t answer. and it is not yet in your nature to something left unsaid. hope i make not serious trouble?
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Regarding the mathematical universe, I agree. I actually remain agnostic on a lot of it. I think mathematics arises from relations we observe in the world, but is developed into realms that may or may not match entities in the world.
A key question for me, is what is the ontological status of those mathematical objects with no known physical correlates? I wonder if their status is similar to that of failed scientific theories such as the luminiferous aether, that is a conception we hold based on incomplete information. That wouldn’t mean they’re invalid (mathematically), just something that arises because we don’t have full knowledge of those relations in the world.
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With respect, SAP, if you’re still asking that, in the context of the MUH, then you don’t understand the MUH.
On the MUH, all mathematical objects simply exist. There is no distinction between those that are physical and those that are not, except that some are complex enough and stable enough and fine-tuned enough to support life within them, and self-aware life forms will perceive their environments as physical. The ontological status of mathematical objects with no known physical correlates is therefore just the same as all other mathematical objects.
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DM,
I do understand that the MUH asserts that, I’m just not sure I buy it.
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Oh, OK, never mind then. It seemed to me you were asking what the MUH would have us think of such cases.
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No worries. I did begin that comment with “regarding the mathematical universe”, so I can definitely see where I might have given that impression.
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Hi s7hummel,
Sorry, I’m a little confused. What question do you think remains unanswered? I agree with you that the MUH is not falsifiable, if that’s you’re question. I still think there are good philosophical grounds to believe it even if it is not a scientific hypothesis.
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Dammit Sap. You don’t half get me going. I’ll just suggest that this question is metaphysical, such that the views of physicists are irrelevant to anything.
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Sorry guymax. Don’t mean to upset you. Just expressing my thoughts and hoping for conversation.
I agree that this is metaphysics, but I can’t agree that physics isn’t relevant. If it weren’t, we might still think the earth was the center of a universe bounded by a physical celestial sphere. My point though was that we should be careful about making assumptions beyond the evidence.
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Just joking..,
Very careful, yes. I feel we should make no assumptions at all beyond the evidence.
Yet physicists like to do this and, for instance, generally make the assumption that a physical theory can explain the universe on the basis of no possible evidence and contrary to logic. Metaphysics is not so arrogant.
An infinite (and therefore eternal) universe contradicts the scientific evidence and makes no sense. so the idea must be rejected. It would allow us to remain a materialist, however, so the idea is considered ‘scientific’ in the sciences even thought it is a failed metaphysical conjecture. The strategy, as usual, is to reject metaphysics in order to adopt a unworkable metaphysical theory. I’m unable to take this thoughtless approach to science seriously and don’t think anybody should.
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Thanks for the clarification.
In the context of your last paragraph, I wonder what you mean by metaphysics.
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I just mean the study of first principles or the ‘world as a whole’. Same as ever. The search for a fundamental theory using experience and logic, as opposed to just guessing.
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I suspect your average physicist would say that’s what they were trying to do. Of course, many of them would vehemently deny that doing that was metaphysical, although the more thoughtful do admit that scientific theories depend on many first order concepts like causality.
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Yes, and they are wrong. A fundamental theory must be metaphysical. This can be stated with complete confidence. If some physicists have not grasped this then it is amazing. There can never be something that deserves the name ‘fundamental physics’. If we reject metaphysics we must abandon hope for a fundamental theory. It is just the way these things are defined. Perhaps I’m missing something, but if so I don’t know what it could be.
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If something continues as far as the eye can see, it’s a good working hypothesis to assume that it continues beyond. But it’s a mistake to assume that it continues forever.
To assume that the world ceases to exist if we can’t observe it is an error. To assume that we know about the parts we can’t see is another type of error.
It’s the job of a theoretical physicist to propose theories that fit the facts and then wait for someone to disprove them. The big leaps forward in physics have occurred when someone has proposed an outrageous idea and then everyone failed to disprove it.
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I definitely agree with your first two paragraphs. On the third, I’d only add that each assumption theories make beyond observational data historically lowers the probability of their success.
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Outrageous ideas definitely carry with them a high risk of failure. And yet it seems that nature is often kind to big thinkers who embrace the principle of universality. Of course, sometimes it kicks them into the dust and laughs in their face. Nature can be cruel like that.
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“Beginning of the universe” is a fundamentally incomprehensible concept. I don’t think, this concept can even be properly defined. To make sense, words must have definitions. The word “define” comes from latin “finis” – end, boundary, limit. “To define” is to draw a boundary between what something is and what something is not. “Beginning of something” designates time before which this “something” IS NOT and after which this “something” IS. To me, “the universe” simply means “everything”. It’s possible to define “everything” in a limited context as, for instance, “all things in a box”. In this case, “the box” is the boundary between “everything” and “not everything”. If we expand the boundaries, “everything” becomes increasingly difficult to define. “Everything in the house” is more ambiguous than “everything in a box”. Still, the concept is somewhat comprehensible. “The universe” is “everything” in a box where the box is expanded into infinity. We can, kind of, comprehend what that means, but only as an abstract concept, like all other “infinities”. However, “everything” in the context of universe loses meaning because it’s impossible to draw a boundary between “everything” and “not everything”. “Nothing” could not “exist” because there is no such thing as “nothing”. This is where the language and logic start to fail and the words stop making sense.
Perhaps, a better definition for the beginning of the universe is not the time before which the universe did not exist, but the time before which we cannot define time, space, matter, laws of physics, and all other concepts which physics commonly manipulates.
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I totally agree about it being incomprehensible. Well said.
The problem is that contemplating the beginning of the universe, or before the universe, or outside of the universe, may not be something we can do using concepts from within the universe such as matter, energy, time, and space. As patterns of matter and energy within spacetime, we may be unable to conceive of what might have been before or outside of it. Still, if we were to come across evidence of a beginning, we’d have to cope.
Of course, we could always say it was the beginning of the universe as we know it, like we do with the big bang. It’s hard to conceive of evidence that would make us sure there was nothing prior to a certain point. It might be that all we could observe would be a lack of evidence for any prior state.
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Words “nothing” and “was” don’t fit together well, IMO.
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“Nothing” in the context of cosmology seems like a pretty tough concept no matter which words it’s used with.
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As I mentioned, words are always defined in relation to something else. Definition is a line between what thing “is” and what it “is not”. “Nothing in the fridge” has meaning as long as “the fridge” is defined. But “nothing” in general or in the context of the universe (everything) is meaningless. It’s not a “pretty tough concept”. It’s simply a meaningless concept. There’s nothing to understand (sounds like a pun). Trying to understand “nothing” may be a good practice for Zen monks, but not for scientists.
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“Beginning of the universe” need not be any different to “Absolute zero of temperature”. Before the absolute zero was discovered in the 19th century, no one suspected a limit to temperature. The absolute zero of temperature has not been realised in a laboratory (it can never be) but we know it exists as a limit.
As far as the “Beginning of the universe” we do not yet know for certain if there was one, but one day we might know. It is not incomprehensible or meaningless.
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I think the incomprehensibility is that a start implies there was a before the start, but in the case of the start of reality, there would have been no “before”. As a pattern of matter in space and time, I find that a difficult concept, although it wouldn’t be the first such difficult concept I accepted based on evidence, when or if we found that evidence.
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If the language of “start” causes problems, try “earliest possible time” or simply t=0.
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t=-1? Sorry, couldn’t resist 🙂
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You might as well talk about negative mass or negative temperature.
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I’ve actually seen negative mass discussed in a number of articles, usually in discussion of things like wormholes. But even negative temperature (on the Kelvin or Rankine scale) is sometimes discussed as a concept.
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Yes, quantum effects can throw things at us that make no sense to our classical intuition. Perhaps quantum effects will do the same with time. I wouldn’t be at all surprised if the universe came into existence because of a quantum fluctuation.
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t=-1 is not obviously absurd to me, Steve.
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I didn’t say it was!
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i see that finally something moved. Finally some lively discussion. But this is still not enough for my language needs. also, the cognitive process probably will not suffer from more arguments!
(dm) Please forgive me but it seems to me that this problem presents you some problems. Well, even beautiful minds have moments of weakness.
(sap) thanks for the wonderful answer… i hope you come back to this topic in a deeper way?
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Hi s7hummel,
I’m not following you, I’m afraid.
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“If so, the only way that we could ever falsify that theory…” i think that this text also contains some doubts on that was not your response. and i’m sure that in your nature there is no such weakness would leave something unanswered…
from… “The Universe is Made of Mathematics” – entry by SelfAwarePatterns (Dec 2013) “If I understand correctly, the MUH asserts that mathematics is a superset of the universe (or all universes). If so, the only way that we could ever falsify that theory…” — but if i make trouble or a problem is too difficult, then i disappearing…
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I agree with you that the MUH is not falsifiable, if that’s you’re question. I still think there are good philosophical grounds to believe it even if it is not a scientific hypothesis.
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(dm) to end this topic i have to say… i tried to analyze all of your entries for the MUH and i must say that you have a very powerful mind! so i can’t say that i can see serious inaccuracies. doesn’t mean that anything has convinced me… so i can only say… ‘i give up’! at this stage of my thinking i have no chance!!!
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s7hummel,
I’d be interested in knowing what aspects of this you’d like to see explored.
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(sap) i’m not still on such a level of the intellectual development to be able to create an accurate framework for these issues. so let us stay at the natural development of revealing secrets of this Universe. of course at the significant contribution of such wonderful minds which we are meeting on wp!
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