To break this down, according to special relativity, objects that are close together cannot move faster than the speed of light with respect to one another; however, there is no such law for objects that are extremely distant from one another when the space between them is, itself, expanding.
Ultimately, this means that we could only reach the edge of the observable universe if we develop a method of transport that allows us to either 1 Travel faster than the speed of light something which most physicists think is impossible 2 Transcend spacetime by using wormholes or warp drive, which most physicists also think is impossible.
What is outside the observable universe? However, we have several theories regarding what exists in the great unknown. Despite its strangeness, this first idea is one of the easiest to digest. Astronomers think space outside of the observable universe might be an infinite expanse of what we see in the cosmos around us, distributed pretty much the same as it is in the observable universe.
This seems logical. And honestly, who can envision a universe that has an end—a huge brick wall lurking at its edge? So, in some ways, infinity makes sense. That means that, if this holds true and we follow it to its logical conclusion, somewhere out there, there is another person who is identical to you in every possible way, and there is also a you who is only slightly different from you in every possible way one is an inch shorter; one got hit by a bus 5 years ago and died; one has a missing finger etc.
This notion seems inconceivable. But then, infinity is rather inconceivable. One possible cause: Massive structures outside the observable universe exerting gravitational influence. Instead of solid, liquid, or gas, all the matter in the entire Universe was in the form of an ionized plasma. A Universe where electrons and protons are free and collide with photons transitions to a neutral The way we arrive at the size of the Universe today is through understanding three things in tandem:. By taking the Universe we have today, we can extrapolate back to the earliest stages of the hot Big Bang, and arrive at a figure for both the age and the size of the Universe together.
The size of the Universe, in light years, versus the amount of time that's passed since the Big This is presented on a logarithmic scale, with a number of momentous events annotated for clarity. This only applies to the observable Universe.
From the full suite of observations available, including the cosmic microwave background but also including supernova data, large-scale structure surveys, and baryon acoustic oscillations, among others, we get our Universe. That's the limit of what's observable. Any farther than that, and even something moving at the speed of light since the moment of the hot Big Bang will not have had sufficient time to reach us.
As time goes on, the age and the size of the Universe will increase, but there will always be a limit to what we can observe. Note that we're limited in how far Anyone living in our Universe, at any location, would see almost exactly the same thing from their vantage point. So what can we say about the part of the Universe that's beyond the limits of our observations? We can only make inferences based on the laws of physics as we know them, and the things we can measure within our observable Universe.
For example, we observe that the Universe is spatially flat on the largest scales: it's neither positively nor negatively curved, to a precision of 0. If we assume that our current laws of physics are correct, we can set limits on how large, at least, the Universe must be before it curves back on itself. The magnitudes of the hot and cold spots, as well as their scales, indicate the curvature of the To the best of our capabilities, we measure it to be perfectly flat.
Baryon acoustic oscillations provide a different method to constrain this, but with similar results. Observations from the Sloan Digital Sky Survey and the Planck satellite are where we get the best data. They tell us that if the Universe does curve back in on itself and close, the part we can see is so indistinguishable from "uncurved" that it must be at least times the radius of the observable part.
This means the unobservable Universe, assuming there's no topological weirdness, must be at least 23 trillion light years in diameter, and contain a volume of space that's over 15 million times as large as the volume we can observe. If we're willing to speculate, however, we can argue quite compellingly that the unobservable Universe should be significantly even bigger than that. The observable Universe might be 46 billion light years in all directions from our point of view, Over time, we'll be able to see a bit, but not a lot, more of it.
The hot Big Bang might mark the beginning of the observable Universe as we know it, but it doesn't mark the birth of space and time itself. Before the Big Bang, the Universe underwent a period of cosmic inflation. Instead of being filled with matter and radiation, and instead of being hot, the Universe was:. Inflation causes space to expand exponentially, which can very quickly result in any pre-existing If the Universe is curved, it has a radius of curvature that is at minimum hundreds of times larger than what we can observe.
It's true that in our region of the Universe, inflation came to an end. But there are three questions we don't know the answer to that have a tremendous influence on how big the Universe truly is, and whether it's infinite or not. It's possible that the Universe, where inflation occurred, barely attained a size larger than what we can observe. It's possible that, any year now, the evidence for an "edge" to where inflation happened will materialize.
But it's also possible that the Universe is googols of times larger than what we can observe. Until we can answer these questions, we may never know. Because of the connection between distance and the speed of light , this means scientists can look at a region of space that lies Like a ship in the empty ocean, astronomers on Earth can turn their telescopes to peer The word "observable" is key; the sphere limits what scientists can see but not what is there.
But though the sphere appears almost 28 billion light-years in diameter, it is far larger. Scientists know that the universe is expanding.
Thus, while scientists might see a spot that lay If inflation occurred at a constant rate through the life of the universe, that same spot is 46 billion light-years away today, making the diameter of the observable universe a sphere around 92 billion light-years. Centering a sphere on Earth's location in space might seem to put mankind in the center of the universe.
However, like that same ship in the ocean, we cannot tell where we lie in the enormous span of the universe.
Just because we cannot see land does not mean we are in the center of the ocean; just because we cannot see the edge of the universe does not mean we lie in the center of the universe. Scientists measure the size of the universe in a myriad of different ways. They can measure the waves from the early universe, known as baryonic acoustic oscillations, that fill the cosmic microwave background. They can also use standard candles, such as type 1A supernovae, to measure distances.
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