If you could stare far enough into space, you would be looking at the back of your own head. And so, as the Universe expands, it would take you longer and longer to lap the Universe and return to your starting position. But there's no direction you could travel in that would take you outside or "off" of the Universe. Even if you could move faster than the speed of light, you'd just return to your starting position more quickly. We see other galaxies moving away from us in all directions just as our ant would see other ants moving away on the surface of the balloon.
A great analogy comes from my Astronomy Cast co-host, Dr. Pamela Gay. Instead of an explosion, imagine the expanding Universe is like a loaf of raisin bread rising in the oven. From the perspective of any raisin, all the other raisins are moving away in all directions.
But unlike a loaf of raisin bread, you could travel in any one direction within the bread and eventually return to your starting raisin. Remember that our entire comprehension is based on 3-dimensions.
If we were 4-dimensional creatures, this would make much more sense. For a much deeper explanation, I highly recommend you watch my good friend, Zogg the Alien explain how the Universe has no edge. After watching his videos, you should totally understand the possible topologies of our Universe. I hope this helps you understand why there's no answer to "what is the Universe expanding into?
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The information you enter will appear in your e-mail message and is not retained by Phys. You can unsubscribe at any time and we'll never share your details to third parties. More information Privacy policy. In many local regions, however, the energy may settle by random chance into a stable state, stopping inflation and forming bubble universes. Each bubble universe —ours being one of them —would be described by its own Big Bang and laws of physics.
Our universe would be part of a greater multiverse, in which the fantastic rate of eternal inflation makes it impossible for us to encounter a neighbor universe.
The Big Bang also predicts that in the early, hot universe, our fundamental forces may unify into one super-force. Mathematical string theories suggest descriptions of this unification, in addition to a fundamental structure for sub-atomic quarks and electrons.
In these proposed models, vibrating strings are the building blocks of the universe. Competing models for strings have now been consolidated into a unified description, and suggest these structures may interact with massive, higher dimensional surfaces called branes.
Other branes—containing other types of universes—may co-exist in hyperspace, and neighboring branes may even share certain fundamental forces like gravity. Both eternal inflation and branes describe a multiverse, but while universes in eternal inflation are isolated, brane universes could bump into each other. Some suspect these differing multiverse hypotheses may eventually coalesce into a common description, or be replaced by something else.
During this time, which lasted more than a half-billion years, clumps of gas collapsed enough to form the first stars and galaxies, whose energetic ultraviolet light ionized and destroyed most of the neutral hydrogen. Although the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity, about 5 or 6 billion years after the Big Bang , according to NASA, a mysterious force now called dark energy began speeding up the expansion of the universe again, a phenomenon that continues today.
A little after 9 billion years after the Big Bang, our solar system was born. The Big Bang did not occur as an explosion in the usual way one think about such things, despite one might gather from its name.
The universe did not expand into space, as space did not exist before the universe , according to NASA Instead, it is better to think of the Big Bang as the simultaneous appearance of space everywhere in the universe. The universe has not expanded from any one spot since the Big Bang — rather, space itself has been stretching, and carrying matter with it. Since the universe by its definition encompasses all of space and time as we know it, NASA says it is beyond the model of the Big Bang to say what the universe is expanding into or what gave rise to the Big Bang.
Although there are models that speculate about these questions, none of them have made realistically testable predictions as of yet. In , scientists from the Harvard-Smithsonian Center for Astrophysics announced that they had found a faint signal in the cosmic microwave background that could be the first direct evidence of gravitational waves, themselves considered a " smoking gun " for the Big Bang.
The findings were hotly debated , and astronomers soon retracted their results when they realized dust in the Milky Way could explain their findings. The universe is currently estimated at roughly In comparison, the solar system is only about 4. This estimate came from measuring the composition of matter and energy density in the universe.
This allowed researchers to compute how fast the universe expanded in the past. With that knowledge, they could turn the clock back and extrapolate when the Big Bang happened. The time between then and now is the age of the universe. What really happened is that the big bang is the universe. It was not an explosion in space; space is the explosion. The space between objects has been expanding ever since. The fact that this is unfathomable should make it all the more amazing.
Andrew Busch. Instead of thinking of the universe as inflating like a balloon, I think of it as a giant ball of dough being stretched in all directions by several chefs. All we know, and this is what we mean by the expansion of the universe, is that, on average, every galaxy is getting increasingly far away from every other galaxy, at an increasing rate, with no central point. So, as far as you know, nothing exists outside the flat.
It just is everything. Is it infinite or finite? There are many unanswered or even unanswerable questions at the moment.
We may never know, because all our measurements are constrained to the observable universe. There are limits to what the human brain can comprehend — it is constrained by its evolutionary context. Well, it might be acceptable to some people, but not to me.
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