The word "beginning" is contextualized to the concept of time, and time is an abstraction that exists within the universe. To say that the universe has a beginning is to say that time has a beginning. But that is nonsensical; something only has a beginning if its existence is preceded in time by other existence. The existence of time can't be preceded in time by the existence of something else. For that to have meaning we need some "meta-time". "Meta-time" can only exist in a "meta-universe": a larger, imaginary universe in which we are embedding "our" universe. Well, did that larger one have a beginning, and why would we even consider it a separate universe at all?
Physicists Debate Hawking’s Idea That the Universe Had No Beginning
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Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#112Earlier quoted context omitted.
Time is another dimension that we 'perceive'. Hence for our frame of reference, which is bound by time, asking what is outside this frame of reference makes no sense. But frames of references are relative and meant to be broken. Similarly it is hard to imagine any object that can be purely 2D in nature, because we are biased to perceive the world in 3D. So we think that every object has to be 3D, even the smallest or…
> The point I am trying to make is that time is just our perception. So is causality—I'm not really sure what your point is.
Because we are limited by our perceptions of time (and causality as well) doesn't mean we shouldn't wonder what could have been before the start of the universe. Maybe time started when universe started, or maybe time always existed and was super slow or literally paused at singularity - the gravity is so high (way more than the gravity of a super massive black hole) that time had paused. So maybe there was something before the big bang and I don't think 'talking about that makes no sense' should stop us from talking about it :)
I am also confused a tad about the point I wanted to make though, lol. Maybe causality and time is perceived differently in higher or other dimensions that we do not perceive as of now in our human level of evolution. So the assumption of causality exists only due to time being present could be something relative to our perceptions and not true
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#113This seems different than the concept of infinite time, where prior to the big band there was something the collapsed into a ball of energy and maybe someday our universe will collapse back again (which has lost merit since we've seen matter in the universe isn't slowing down in spreading apart, but accelerating .. meaning in a few trillion years, atoms may be so far apart that light can't reach anything .. the event…
there is an assumption the shuttlecock is the Universe and there is nothing outside to observe the object. It's not an assumption, it's explicitly part of the model. Same with "What's south of the south pole." It ignores the stars and galaxies past Earth itself. If I say "the latex in this balloon is like the surface of the earth," I'm not so much ignoring the stars & galaxies, they're just not part of the analogy. I…
> Is your point that, for an object to be curved, there must be something for it to curve into? For example, in order for a 2D surface (like the latex in the balloon) to be curved, it necessarily must be in a 3D (or higher) space?
Given the context I'm guessing you asked this rhetorically, but if not: it is not true in general that a curved n-dimensional object must be embedded in a n + k-dimensional space. Curvature can be intrinsic.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#114This seems different than the concept of infinite time, where prior to the big band there was something the collapsed into a ball of energy and maybe someday our universe will collapse back again (which has lost merit since we've seen matter in the universe isn't slowing down in spreading apart, but accelerating .. meaning in a few trillion years, atoms may be so far apart that light can't reach anything .. the event…
Wikipedia's 'Timeline of the Far Future' is a great article on the posibilities of our universe's fate [0]. Of note are the entries near the end of the list. Year 10^(10^(50)) : Estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease [1] Year 10^(10^(120)) : High estimate for the time for the universe to reach its final energy state, even in the presence of a false vacuum. Year…
Boltzmann brains may not occur after all [0], which is reassuring [2]. See De Sitter Space Without Dynamical Quantum Fluctuations [1].
[0] http://www.preposterousuniverse.com/blog/2014/05/05/squelchi...
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#115Earlier quoted context omitted.
Sorta. We are in this thing called space-time. It came out of the Big Bang (we think). There is a finite amount of it (about 45 GLY in radius, maybe). You can only ever see about 14GLY of it due to some speed limits. You can't get to an edge or boundary of space-time because it's not 3-D, it's curved in this really weird way. There are a lot of holes in space-time that we're still thinking a lot about. For some reaso…
The hot big bang is an event in spacetime. It does not generate the manifold itself, although the geometry of the manifold necessarily reflects it, especially near the event itself. There is no evidence to support finiteness of spacetime; there is no reason why there aren't events in the infinite future. The only reason to suspect there are no events in the infinite past is a classical picture of a gravitational sing…
Thank you for your comments, they're continually a joy to read.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#116Earlier quoted context omitted.
If you are restricted to the typical 3 dimensions of movement (and 1 through which we are non-optionally traveling) - you should either get to a physical boundary, or you end up in a loop, right? I mean, you won't travel so far you end up in Tuesday.
Sorta. We are in this thing called space-time. It came out of the Big Bang (we think). There is a finite amount of it (about 45 GLY in radius, maybe). You can only ever see about 14GLY of it due to some speed limits. You can't get to an edge or boundary of space-time because it's not 3-D, it's curved in this really weird way. There are a lot of holes in space-time that we're still thinking a lot about. For some reaso…
I'm of the impression that "the universe is getting bigger and bigger" is the other side of the coin from "space time is curved in this really weird way". Also, I'm under the impression that a curved spacetime doesn't contradict the notion of 3D space or 4D spacetime. As I understand it, a flat spacetime is one in which space neither expands nor contracts, and convex or concave spacetime refer to space that either expands or contracts (I forget which is which). Based on observations that things are getting farther apart (or perhaps that they are accelerating away from each other?), we think spacetime has a curve.
I'm sure I'm misunderstanding something; hopefully someone can jump in and correct me.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#117What does it even mean to ask “what happened before time”? The question seems nonsensical to me.
It's nonsensical to wonder what happened in our universe before it existed, but if our universe has an external superuniverse, it's not illogical to wonder what happened there that caused our universe to exist.
> if our universe has an external superuniverse
This is also meaningless, scientifically: there is nothing you can measure which is outside the universe. Things like a holographic universe are inherently untestable. I hope we continue looking for testable things, but this speculative path rapidly leads away from science and physics and into "linguistic tricks to confuse humans". It's not even philosophy at that point, it's just arguing over semantics.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#118Pure nothingness has no potential for creation. The laws of physics don't invent themselves, so it would seem that true "nothing" never existed. I'm not talking about the quantum soup of the vacuum of space, because that is something.
If we take Hawking's idea that the universe smoothed out to a zero point where there was no time and nothing else, how does that point because laws of physics, gravity, etc? What properties of a zero point (that had no properties) cause it to create an inflationary universe?
Everything breaks down at that point, because trying to use mathematics or physics to explain something that existed before mathematics and physics doesn't work.
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#119Say we could break any physical rules of our current universe, is there a good theory that would explain how something might have been created out of nothing? i.e. imagine for a second that we're in a simulation and that the current laws of physic are just arbitrary created by a "host". This "host" could have very different physical laws. Could we think of any theory that would explain the creation of something out o…
There's an interesting philosophical line of thought that distinguishes between things that are necessary and things that are contingent.
A necessary thing must exist; it can't not exist. A contingent thing may exist, or it may not.
In the classical definition of God, he has no beginning or end. He was not created by some other force. He exists necessarily. He just _is_. In fact, many theists describe God using terms such as "being itself" or "pure is-ness". Even the Hebrew name for God -- I AM -- makes references to this. And if God is necessary and uncreated, it gets around the question of, "Well, who created God?"
But I've heard people point out that if you can say that God just is, without having been created, then why not say that the universe just is, without having been created?
I think the answer to that question lies in this distinction between necessary and contingent things.
Theists who have a classical conception of God would argue that God is necessary, but the universe is contingent.
If you're interested in the philosophy behind this, here's an interesting resource: https://plato.stanford.edu/entries/god-necessary-being/
Re: Physicists Debate Hawking’s Idea That the Universe Had No Beginning
#120Earlier quoted context omitted.
With all respect, I think we generally live in a human society that has been built around that very constraint.
Curious to know why that is. Would you mind expanding?
As biological organisms, notions of birth/death are hard wired into the lowest levels of our cerebral kernel which serves as the foundation for every higher level of consciousness. As such, we only have the fundamental architecture to perceive an existence that is (literally) grounded in a small gravity well, with all of our primary circuitry distinctly focused on what is in “front” of both in space and time. As organisms, we cannot directly experience time that preceded our own existence, we can only mentally model that experience through intuition. That works well enough for relating to the existence of other organisms and the physical world we share, but that relatability breaks down quickly at larger space/time scales.
Incidentally, though our individual multicellular existences may follow a birth/death cycle, the molecular information flow (DNA) that transcends our organismal existences may perhaps provide the closest approximation to a model necessary to conceptualize possible relationships between multiple space-times.
(I’m clumsily alluding to the blackhole/whitehole infinitely branching multiverse concept, with DNA playing the part of sub-atomic mass/energy primitives which encode the structure of new unidirectional space-times/universes in an endless phylogeny which ultimately still doesn’t get us anywhere closer to “where did it all begin?” but surely expands the scope of the investigation wide enough to buy us enough time to keep procrastinating... Ok, back to work.)
disclaimer: I only got a B in undergrad physics and have absolutely no clue what I’m talking about.