If (theoretically) the Universe can be traced back to (almost) a finite point (big bang) but has no cause (because there was nothing before it) can’t it be argued that we’re a product of something that never happened?
If you argue that it did happen then why isn’t plausable to as what made it happen? And if something made it happen, wouldn’t it have had to do so before it happened, thus creating the big bangarooni? Everything seems to be flying away from itself pretty fast for nothing to have caused it to.
If you argue that it did happen then why isn’t plausable to ASK what made it happen? And if something made it happen, wouldn’t it have had to do so before it happened, thus creating the big bangarooni? Everything seems to be flying away from itself pretty fast for nothing to have caused it to.
I will add Universe in a Nut Shell to my annual literary christmas list. I’ve had his first book for some time and I must say, I fell in with the people who tried to read it as a novel and not as a guide. I will persevere. And yes, it is very interesting stuff - If I may call it that!
There was NOT “nothing there before it”. There is no such thing as before it. Neither did the Big Bang happen. It exists, *timelessly*.
I admit that my puny mortal mind is having some trouble with this.
If there was no such thing as “before” the Big Bang, can we meaningfully exclude the possibility of this:
Because it seems that without the influence of time, there can’t be any more than one Big Bang and one Big Crunch. In other words, if events can only happen in time after the Big Bang and before the Big Crunch, then there can be only one Big Bang and one Big Crunch.
And I hate to heap question upon question, but these have been bothering me for quite some time. From your other thread.
So what does it mean to say that the universe is expanding? What is it expanding into? Or maybe a better way to ask that question is, what is happening at the edges of the universe that allow it to expand? Is space being created?
Another one. If the universe is expanding, and the rate of its expansion appears to be increasing, then why should we expect that a Big Crunch is even possible? Is it because we expect that Dark Energy will eventually run out? And speaking of Dark Energy, do we know if it’s a pull or push force?
Sorry to be such a pest. Thanks for sharing the knowledge.
As the contiunally big bang-big crunch relies on yet unkown physics it cannot be said, of course given the amount of matter in the universe this scenario looks distinctly unlikely.
The big crunch appears in several models of the unievrse, yet these models seem highly unlikely due to the low density of the universe and the fact that we have observed the universe to be currently in a period of inflation (i.e. accelarted expansion). Dark energy is a repulsive force, though I’ve not read up on it yet.
If there’s no such thing as “before the big bang” then why is the universe 12 billion years old and not 2 billion or 100 billion years old? If nothing provoked the universe into materializing then how can it have an age? If it didn’t “happen” but just “is” wouldn’t that be an ageless universe?
Sorry for if I seem thick.
You need to remember the Big Bang was the creation of time and space. Space-time exists only after the Big Bang event, not before it.
The time estimate is not solely based on abstract conjecture. Part of what allows us to figure the minimum age of the universe is the composition of the oldest white dwarf stars. The theoretical models match very closely to what we see, and what we see appears to be 13 billion years old.
Exactly the sort of thing I was talking about. Why can’t you “buy” it? Because many things from your experience within the universe speaks against it. But these insights and intuitions have no necessary meaning when attempting to discuss the universe from an external perspective (which may or may not even be a valid perspective). The rules you learned in all your years of playing baseball may have no meaning when applied to playing golf on the moon.
Age:
To understand it, you have to forget about the idea that there is anything “outside” of the universe. The universe is space; space doesn’t extend beyond the universe. Therefore, it’s nonsensical to ask what the universe expands into.
The best way I have found to wrap my brain around it is to simply subtract one dimension. Leaving time out of the equation for a moment, imagine a 2-dimensional universe instead of our 3-dimensional one. Such a universe might be likened to a balloon. Let’s say there are 1,000 ants walking on the surface of the balloon. An ant can walk in any direction across the balloon, and eventually end up right back where he started. From the ant’s point of view, there is no “edge” of the universe; he can keep walking infinitely. Now imagine that the balloon is slowly inflated. The distance between each ant on the surface of the balloon becomes greater, but from the ants’ point of view, there still is no “edge” to their universe. So it’s expanding, yet there is no edge.
Now you might say, “but the balloon is expanding into the air”. Remember, however, that this is a 2-dimensional universe, so there is no air, nor is there an outside or inside of the balloon. Only the 2-dimensional surface exists. Now here’s where you have to let go of your Earthly preconceptions: Imagine that we are the ants, and the balloon has 3-dimensions rather than 2. We can move in any of 3 dimensions, but we will never reach the “edge” of the universe. Since we have no way to view a 3-dimensional universe from “outside” as we can with a 2-dimensional balloon, you just have to grasp the concept intellectually rather than intuitively.
For this concept, it helps to think of time as a 4th dimension. Think of “12 billion years” as a place rather than a time. The universe is timeless, but we happen to be at the place in the universe that is “12 billion years old”. The places “2 billion years old” and “100 billion years old” also exist, but we aren’t there.
Agreed, introducing other “domains” does imply that time exists elsewhere than “our” universe. However, I must stress that it is entirely possible that we cannot know anything about these domains “past” the Planck epoch (ie. the first 10^-35 second of the universe), and that they may only have passing similarities to “our” time, such that the words before, change, cause etc. are pretty much meaningless and should be reserved only for “us”.
Again, the universe has no “edge” past which pure nothingness exists. It is perhaps less misleading to theing of the space within it expanding. The usual analogy is to paint galaxies on the surface of a balloon and inflate it: The galaxies move apart but the surface of the balloon has no “edge” into which it is expanding.
This “age” is merely the “distance to the base of the hill” at which “time changed direction”.
theing?
think!
Well I’ll be blowed.
We’ve really got to stop this spooky premeditative telepathic stuff, friend, it’s beginning to freak me out.
Ok Blow & Sentientmeat , put that way I can understand the age anology.
If it is timeless then how can it still be expanding? Would that be just from our perspective? In other words, would “God” see his universe expanding the same way we do? Or would it be at every stage all at once?
Our part of the universe is not timeless, obviously. The part of the 4-D universe which is timeless is the part 12 billion years “distant”. We are not there!
Elsewhere in the universe (ie. at different times) the universe is different “sizes”, although this again is a little misleading in that it implies some perfect scale - perhaps it would be better to say it has a different expansion coefficient at these different times.
I know it sounds like I’m making things deliberately difficult here, but it is imperative that one divests oneself of the “everyday” notion of time and three dimensional space, and starts to treat them more flexibly. Tricky, I know!
I realize this is probably calls for an extremely complicated answer, but how do we know that space itself is expanding? How do we know that the stuff in space isn’t expanding into some (perhaps) infinite amount of space that’s already there? I ask because it seems like if space is both infinite and empty, it wouldn’t have any measurable properties by which we could tell whether it’s expanding or static.
Thanks, MC Master of Ceremonies, blowero, and SentientMeat, for your help. Your minds seem to be nearly as infinite as space itself.
What God would “see” would depend where he looked, I suppose. Different times are simply different facets of the same universe, as in this chestnut:
The Blind Men and the Elephant
The blind men are all observing the same elephant, but from each vantage point, it appears to be completely different.
Why we seem to be stuck moving in one direction in time is still somewhat of a mystery. There are theories, but unless I’m mistaken, we haven’t quite figured it out yet.
The most fundamental reason that we know it’s expanding is that from our point of view the expansion is the same in all directions if it was a local expansion then we would not expect this, due to the Copernican cosmological principle as we would have to be at the exact centre. Other evidence includes the CMBR is highly homogenous and isotropic in all directions, the only reasonable explaination for this is that it orginated from the same point which rules out nearly all other theories excpet the big bang and the expansion of space. Add to this that this is what one of our most accurate theories - general relativity predicts, it is difficult to construct a cosmology consistent with the veidence that does not include the expansion of space.
The problem with discussing the Big Bang (BB), which often gets forgotten, is that it is based on our best theories to date. However, our theories break down exactly when we get close to the BB. In other words, the real answer to the OP is “We don’t know. Our theories aren’t good enough to extrapolate to the BB, much less before it.”
Anyone who claims otherwise is talking out their posterior region, and that includes string theorists and quantum cosmologists who claim to be able to describe what goes on at the BB. You can tell from the contradictions in their accounts that there is no agreement on what goes on pre-BB.
Some of the options are:
- Before the BB the universe was tiny and immensely hot.
- Before the BB the universe was infinite and cool.
- There was space, but no time.
- There was another universe that collapsed and became the BB.
- There was no before.
(I’m not making this up.)
What we know is that distant galaxies seem to be receding from us. When we apply General Relativity (GR) to the universe as a whole, we find that it allows for solutions that include the expanding universe. Since we have other reasons to believe that GR is correct, we suspect that GR is a good description of our universe.
The reasons no one talks about a matter-expanding-into-empty-space universe are more philosophical than scientific.
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We don’t see any empty space. We see galaxies every direction we look. Our theories (GR) can deal with an expanding universe without postulating empty space around it. Why introduce an unnecessary postulate? (This is known as Occam’s razor.)
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We know of no reason our position in the universe should be special. We assume that the regions of the universe we can’t see are similar to the regions we can see, unless there is a good reason to do otherwise.
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If the BB happened at one point in otherwise empty space, what was special about that point where it happened? In the usual BB scenarios, the BB happens at every point in space. There is no need to assume one particular point was special.
Hope this helps!