It’s 156 billion light years across. That’s the current estimate. “How can that be,” you ask, “if the universe is only supposed to be about 13.7 billion years old? How could it grow to such a size in so short a time?”
The answer that is proposed is that the universe didn’t simply start flying out from the Big Bang. It did that–the theory goes–but there is supposed to be more to it. The universe also is inflating like a balloon, so the space that the energy from the Big Bang rushed into has inflated and continues to inflate, allowing the universe to grow larger than mere expansion at the speed of light would allow.
If it helps, think of an ant walking on the surface of a balloon. The ant himself can only go so fast, but if the balloon he’s standing on is expanding, he can cover much more distance than he could under his own power. The same way, a light particle can only fly through space so fast (186,000 miles per second), but if the space it is travelling through is itself is expanding, the light particle (or wave–whatever) will cover more distance.
At least that’s the theory.
If it’s true, it’s one more reason why the universe is moving apart too rapidly for its gravity to overcome its outward momentum and pull it back in on itself. That means that the universe can’t be an eternally oscillating thing with no beginning that undergoes an endless cycle of expansions and collapses.
In other words, the new finding is supportive of the idea that the universe had a beginning and thus was created.
Even if it were proven to be an ever-expanding-and-collapsing universe, how would it not have had a beginning? I.e., how would it be any less likely that it was created?
Very cool, thanks Jimmy.
Brad,
An ever-expanding-and-collapsing universe is one that can theoretically be viewed as a perpetual-motion machine, one that has existed for all infinity and will continue to exist for all infinity, never beginning and never ending.
Such a universe, even if it really were without beginning, wouldn’t DISPROVE the existence of a Creator (I think Thomas Aquinas thought it was philosophically possible, apart from special revelation, that the universe had always existed and was eternally contingent upon God, perhaps not unlike how the Son is perpetually begotten of the Father). But it would remove one argument for proving that a Creator exists.
OTOH, a universe that represents a one-way process from an initial state to an end state (e.g., zero entropy to infinite entropy, Big Bang to heat death), with no mechanism for returning or rebooting, is a universe that seems to require a jump-start from outside.
IOW, to the extent that we can discount oscillating and steady-state universe theories, we seem to have a universe in which some event was the first physical event that ever occurred… and the cause or origin of this event would seem to have to be non-physical, from outside the natural order.
But what’s it expanding into?
Even an expand-contracting universe would have to have a finite number of expansion-contraction cycles, because of the 2nd law of thermodynamics. There would still have to be a first big bang, followed by cycles of expansion-contraction. Each of these would be bigger than the last, until one got too big to contract again.
John,
I think that the “big-bang / big-crunch” theory involves the idea that the laws of physics work radically differently in the contraction stages from the expansion stages. I’m no expert, but I think it’s hypothesized that the second law of thermodynamics describes the way things work during the expansion stages, and during the contracting stages entropy could work backwards. So in this theory there really is no immutable one-way direction to the history of the universe. I even think I’ve read theories about time itself running backwards and forwards in succession, or something.
We can still do apologetics assuming a big-bang / big crunch model, but it’s certainly easier with the assumption of a one-way universe model. 🙂
The 2nd law of thermodynamics is backwards during a ‘crunch phase?’ That’s a big assumption to make, IMHO. Then again, any astrophysicist who would say something like that is just trying to find some excuse for his pre-determined ideas, and those ideas are philosophical instead of astrophysical, but they won’t admit that 🙂