Time, causality, and prime movers

What's beyond the sky used to be a reasonable question.Sometimes we ask the wrong questions, and answer them with bad answers. One particularly bad question is: “what was there before the Big-Bang?” There are many others, but this one requires a little mental gymnastics in order to get used to modern ideas of time and understand what the consequences are.

“What was there before the Big-Bang” may have looked like a good question before Einstein (if anyone then had a clear idea of a universe expanding from a very dense original state, which they didn’t), but the revolution of Relativity in our concepts of time and space made it scientifically absurd. The word you have to remove from the question is “before”. Substitute “beyond”, and we have something to talk about, but “before” is just absurd in this context. Let me explain.

In a Newtonian, 19th century scientific framework, time and space are fundamental: physical phenomena, and the universe in general, happen in time and space, but time and space aren’t physical phenomena themselves. Einstein showed that time and space are not only relative, but are physical expressions of geometry. They are even in a way consequences of matter and energy. In other words, time and space are properties of the universe. They are of the universe, and don’t make sense outside of it (whatever “outside” could mean when talking about the universe).

As a consequence, time and space as we perceive them are not necessarily useful concepts “everywhere” (and I use that word with scare quotes to express an idea of a place that is more general than what we mean in everyday speech).

The Big-Bang is such a “place”: what scientists mean by Big-Bang is that early region in the universe where everything was so densely packed that our current knowledge of physics breaks down. It is where our ignorance begins, where taking our usual concepts of time and space seriously would lead to absurdities and infinities. The only certainty about what’s beyond the Big-Bang is that we need new science to understand and describe it.

Now if you care about metaphysical questions of origins, that leads to a serious problem: if there is no useful concept of time beyond the Big-Bang, do we still have a useful concept of causation?

Hume’s concept of causation cannot be kept in this context because it is based on time: the cause must be prior to the effect. If “prior” is meaningless, we are reduced to correlation, which can easily be reversed without contradictions.

The only causation that can be used here is the logical concept of necessary causes: if x must exist for y to exist, and y exists, then x exists. The first premise however is a tricky one…

Let’s take a favorite argument from theists, the Kalam cosmological argument. It starts with “everything that begins to exist has a cause”. There are too many problems in this statement to count, but the word we need to focus on is “begins”… The argument continues with “the universe began to exist”. We can stop right there: no, as far as we know, the universe didn’t “begin” to exist because that implies a meaningful notion of time, that we don’t have near the supposed origin of the universe. This argument simply doesn’t work.

I’ll leave you with a final puzzling thought about time and causality. Quantum physics introduced a funny notion that is that the results of some experiments cannot be predicted, and that we can only predict the probabilities of the possible outcomes. Without going into too much details, this doesn’t necessarily eliminate determinism at a fundamental level, but it does confirm that with our limited perception of time, the future is not fixed. One interpretation in particular, the Many Worlds Interpretation, sees us navigating in an infinitely branching network of possibilities. When an experiment is performed, other outcomes than the one measured may seem like they didn’t actualize, but according to Many Worlds, they did, it’s just that this is not where we are. Now here comes the crazy bit: in this interpretation, everything is still fundamentally reversible in time, and the branching that happens about the future also happens for the past. The consequence is that the past may be just as undetermined as the future is.

Have a nice day.

Tags: Science, Naive philosophy, Relativity, Religion

Saturday, September 13, 2014 7:00:00 PM

6 Comments

  • Marcel Popescu said

    First time I see someone admit that (current) science can't tell us anything about what's "beyond" the Big-Bang ("we need new science to understand and describe it").

    "We can stop right there: no, as far as we know, the universe didn’t “begin” to exist because that implies a meaningful notion of time, that we don’t have near the supposed origin of the universe."

    Yes we do. Given the succession of values for time, there is a smallest time, t0 (I hate this font; that's a zero). That is the beginning of the universe.

    Interesting speculation, but once you mentioned the many-world interpretation it went completely off the rails. (Does anyone remember when physics was supposed to explain the real world? When the first law of thermodynamics was still in effect? We're now creating universes willy-nilly.)

  • bleroy said

    You've never heard anyone admit it before because you haven't been paying attention. Here's Sean Carroll saying it, with a bonus quote from Vilenkin inside: "Craig quotes (misleadingly) a recent paper by Audrey Mithani and Alex Vilenkin, which concludes by saying “Did the universe have a beginning? At this point, it seems that the answer to this question is probably yes.” Mithani and Vilenkin are also scientists, and are correspondingly willing to be honest about our state of ignorance: thus, “probably” yes. I personally think the answer is “probably no,” but none of us actually knows. The distinction is that the scientists are willing to admit that they don’t really know." (http://www.preposterousuniverse.com/blog/2012/09/25/let-the-universe-be-the-universe/). Ask any cosmologist and you'll get similar answers. Now you're also twisting my words: I never said that scientists can't tell you "anything" about what's beyond the big bang. They can tell you quite a lot actually, and it's an extremely active field of research, but it's also far from settled.
    There may be a smallest time (as we know it) but that would be the beginning of time, not necessarily the beginning of the universe. There can be something beyond that boundary that's part of the universe.
    You should refrain from talking about what you haven't seriously studied and understood. Many worlds is not creating universes, it's mathematically separating terms of the equation that describes the evolution of the wave function (an equation that describes the real world better than anything else). Energy is perfectly conserved (by the way, you seem to be confused about the 1st law of thermodynamics and conservation of energy). MWI is actually more parsimonious than Copenhagen, because it only needs the field equation, and doesn't require to postulate anything different happens to it during a measurement.
    Then again, why am I even trying to explain cosmology to a young Earth creationist? You don't even believe the universe is billions of years old do you?

  • Marcel Popescu said

    [thus, “probably” yes.]

    Which is a lie by implication, since everyone reads it as "yes", not as "no". You even say right after that: [ I personally think the answer is “probably no,”] - which means you realize there is a difference.

    [There may be a smallest time (as we know it) but that would be the beginning of time, not necessarily the beginning of the universe.]

    This is the kind of absurdity that makes me dismiss a lot of modern science. This statement is not even wrong - it makes no sense. Time is defined by events; if you don't have events, what does having a universe even mean? (Unless you postulate a non-material universe, which gets perilously close to a non-material creator of matter... but even a non-material universe can have events.)

    [Many worlds is not creating universes...]

    Really?

    http://en.wikipedia.org/wiki/Many-worlds_interpretation says: [Hence, even if "new matter" were being generated to create new universes, this would not violate conservation of energy.]

    http://en.wikipedia.org/wiki/Multiverse has two instances of the words "new universes".

    http://science.howstuffworks.com/science-vs-myth/everyday-myths/parallel-universe2.htm tells us [The universe is literally duplicated].

    http://www.newscientist.com/blogs/culturelab/2010/05/the-many-worlds-physicist-couldnt-cope-with-this-one.html tells us [According to Everett, a new universe is created every time...]

    In other words, "your" guys can't get the story straight. It's multiple universes (because that solves some problems) but only until someone points out the absurdity :)

    That final article actually has some nice gems:

    [Everett's story is one of thwarted ambition, blind - and misplaced - faith in the integrity of science...]

    [In some other universe he is still alive.]

    [In one (or more) of the other universes the Many Worlds hypothesis has been proven to be wrong]

    Thanks for making me look it up :)

    Finally, of course I don't believe the universe is billions of years old ;) It's an insane idea and I don't have enough faith in the people supporting it. I also have yet to meet a single person who claims to have tested it. Do YOU have any other reason to accept it except "my priest says so"?

  • bleroy said

    No, you're the only one here who doesn't understand the difference between "yes" and "probably yes". And by the way, that was Carroll speaking, not me, but I happen to agree with both Vilenkin and Carroll. They both were careful to separate what's known from what's their opinion. What do you find unclear about "none of us actually knows"? Nobody's lying here except for you.
    You need to realize that when something doesn't make sense to you, it doesn't necessarily mean that it doesn't make sense. In lots of cases, it means that you don't understand.
    One of the ways you can have a part of the universe where no time exists is to have only space-like dimensions there. Another is if there isn't even any regular form to space and it's a quantum foam instead.
    Reading a bunch of Wikipedia articles is not going to be enough for you to get an understanding of something like MWI. You would need to start at Physics 101, because you don't understand the first word of it currently. The problem with you is that you only look at science to discredit it, and you don't believe that it has anything interesting to say. You always focus on fringe ideas and discard anything that doesn't fit your narrow narrative. I'll attempt one more clarification, but I don't expect you to understand it.
    The universe splitting that happens in MWI is only separating two sets of factors in a mathematical equation, and noticing that those two sets are so neatly separated that they can be considered to have an independent evolution. One can describe the two parts as two distinct universes, but nothing was really created because both parts were there all along. By the way, there is nothing absurd intrinsically about multiple universes. I'm personally not bothered by the idea and you are right that if it solves problems, we're ready to consider it.
    Finally, you revert to your old tricks of poisoning the well... Everett's life has no bearing whatsoever on the validity of his ideas.
    You have never met a person who claims to have tested the age of the universe? That's because you've never talked or listened to a cosmologist. Which is weird because I remember an email conversation where I did claim such things.
    Do *I* have reasons to accept that the universe is billions of years old? Hell, yes. And I have no priest, guru, or even mentor in the matter. Instead, I've studied the field.
    To conclude, I admit I found you amusing in the beginning, but now I'm fairly certain that you have nothing interesting to say, so I'd appreciate if you would refrain from commenting on this blog in the future, except if you have something interesting to bring to the conversation.

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