Universe Could be 250 Times Bigger Than What is Observable

Universe Today ^ | 2/8/11 | Vanessa D'Amico

[LibWhacker]

Our Universe is an enormous place; that’s no secret. What is up for discussion, however, is just how enormous it is. And new research suggests it’s a whopper – over 250 times the size of our observable universe.

Currently, cosmologists believe the Universe takes one of three possible shapes:

• It is flat, like a Euclidean plane, and spatially infinite.
• It is open, or curved like a saddle, and spatially infinite.
• It is closed, or curved like a sphere, and spatially finite.

While most current data favors a flat universe, cosmologists have yet to come to a consensus. In a paper recently submitted to Arxiv, UK scientists Mihran Vardanyan, Roberto Trotta and Joseph Silk present their fix: a mathematical version of Occam’s Razor called Bayesian model averaging. The principle of Occam’s Razor states that the simplest explanation is usually the correct one. In this case, a flat universe represents a simpler geometry than a curved universe. Bayesian averaging takes this consideration into account and averages the data accordingly. Unsurprisingly, the team’s results show that the data best fits a flat, infinite universe.

But what if the Universe turns out to be closed, and thus has a finite size after all? Cosmologists often refer to the Hubble volume – a volume of space that is similar to our visible Universe. Light from any object outside of the Hubble volume will never reach us because the space between us and it is expanding too quickly. According to the team’s analysis, a closed universe would encompass at least 251 Hubble volumes.

That’s quite a bit larger than you might think. Primordial light from just after the birth of the Universe started traveling across the cosmos about 13.75 billion years ago. Since special relativity states that nothing can move faster than a photon, many people misinterpret this to mean that the observable Universe must be 13.75 billion light years across. In fact, it is much larger. Not only has space been expanding since the big bang, but the rate of expansion has been steadily increasing due to the influence of dark energy. Since special relativity doesn’t factor in the expansion of space itself, cosmologists estimate that the oldest photons have travelled a distance of 45 billion light years since the big bang. That means that our observable Universe is on the order of 90 billion light years wide.

To top it all off, it turns out that the team’s size limit of 251 Hubble volumes is a conservative estimate, based on a geometric model that includes inflation. If astronomers were to instead base the size of the Universe solely on the age and distribution of the objects they observe today, they would find that a closed universe encompasses at least 398 Hubble volumes. That’s nearly 400 times the size of everything we can ever hope to see in the Universe!

Given the reality of our current capabilities for observation, to us even a finite universe appears to go on forever.

[LibWhacker]

How can the universe expand faster than c?

Nothing with mass can move through space faster than c. But that tells us nothing about how fast space itself can expand or inflate. Perhaps we should say it tells us nothing about how fast space itself can be created? One physicist I heard said that we shouldn't think of the Big Bang as a one-off event that happened 13.7 billion years ago... It's STILL happening.

[Hatteras]

"If the area of the earth is finite, then what happens when you get to the edge?"

You hold on for dear life.

Seriously though... stepping beyond Earth, you find yourself still within our solar system. When you reach the edge of the solar system, you find yourself still floating within the Milky Way Galaxy. Pushing beyond the bounds of our galaxy we find ourselves still contained within the Universe, but we continue to push ourselves further and further. Is that it? Does it just end there? Or is the Universe part of a more grand system? Does it keep going or would you eventually break on through... say, to the other side? (apologies to Jim Morrison)

The relative order of things would suggest that the Universe is limited such as Earth, the solar system, and the galaxy but that we only have yet to reach the limits of the "universe". And if we did ever reach it and passed beyond, what would you call it? Heaven? ;-) Or is it just a tiny organism contained within a petri dish in some heavenly laboratory?

And my apologies to the more studied in this field for my relative coarse awareness, I appreciate your knowledge and I really am curious. ;-)

[Charles Martel]

Location, location, location. A nice little ocean front property on a planet with oxygen, water and moderate tempratures, near, but not too near, a yellow star is going to be worth a lot more than undeveloped space trapped in a time warp near a black hole in some God foresaken corner of a remote galaxy cluster. Especially if the proptery has access to a reliable airport and a stable government.

So true. That's why when Betelgeuse goes supernova, it'll be no great loss. That neck of the galactic woods already looks like Detroit - or Gary, Indiana.

[TexasTransplant]

I always think of the Universe more as a Multiverse ... just one of many we just don’t know how to see the others

TT

(Pretty sure the solution requires tinfoil and duct tape though)

[Cboldt]

-- stepping beyond Earth, you find yourself still within our solar system. When you reach the edge of the solar system, you find yourself still floating within the Milky Way Galaxy. Pushing beyond the bounds of our galaxy we find ourselves still contained within the Universe ... --

But in each of those, you are working in the framework of being able to "step outside of a smaller part of a larger whole," and see a finite volume from the vantage point of a remote observer. The most common conception is that [empty] space is unlimited, infinite; and if the universe is finite, it occupies only part of infinite space, and in concept it's possible to "step outside" the universe and look back at it - similar to going into outer space and looking back at earth.

My remark sets up a finite mass, finite volume universe that violates the common conception. The volume of the universe, and the volume of space itself are finite, not infinite. But the finite volume doesn't have an "edge," beyond which is emptiness. It is very counter-intuitive to find empty space as being limitable. It is impossible to make a 3-D scale model of this [finite volume of space, without a boundary], like we can make 3-D scale models of the earth, or solar system, or even a galaxy.

Not to say that a finite volume universe is fixed at some value. If the universe is expanding, then the volume/amount of space is expanding [like the area of the earth would increase if the earth's radius increased]. But the universe isn't expanding "into an unlimited nothingness." It is expanding the amount of empty space that can be occupied by matter or energy.

[wolfcreek]

What’s behind the door, under that carpet and is the grass really greener on the other side?

EMENCE

[Graybeard58]

Universe Could be 250 Times Bigger Than What is Observable

If it truly is "unobservable", how can anyone make the above observation?

[LibWhacker]

From http://wmap.gsfc.nasa.gov/universe/uni_shape.html (which doesn't explain what determined the mass and density of the universe!).

Geometry of the Universe

The density of the universe also determines its geometry. If the density of the universe exceeds the critical density, then the geometry of space is closed and positively curved like the surface of a sphere. This implies that initially parallel photon paths converge slowly, eventually cross, and return back to their starting point (if the universe lasts long enough). If the density of the universe is less than the critical density, then the geometry of space is open, negatively curved like the surface of a saddle. If the density of the universe exactly equals the critical density, then the geometry of the universe is flat like a sheet of paper. Thus, there is a direct link between the geometry of the universe and its fate.

The simplest version of the inflationary theory, an extension of the Big Bang theory, predicts that the density of the universe is very close to the critical density, and that the geometry of the universe is flat, like a sheet of paper. That is the result confirmed by the WMAP science.

[LibWhacker]

Here's what the Freeper "Physicist" once said about the universe when someone asked him to explain what the universe was expanding into, and it has a direct bearing on your question:

This question comes up regularly, but it's based upon a misconception that, unfortunately, physicists do more to perpetuate than to correct. Let me see whether I can set you straight.

The problem is that the expanding universe is typically visualized as something like a stretching rubber sheet, or a raisin-laden plum pudding expanding as it bakes. The problem is that these are physical objects that exist in--and take up--some region of space. Over time, these growing objects take up more space, leaving less space for other objects, and either displacing those objects or reaching the limits of the available space. Once the plum pudding fills the oven, there's a problem.

The expansion of the universe isn't like that. The universe is not an object; it doesn't "take up space". It is space. As it grows, it doesn't mean that there is less space for objects; it means there is more space for objects. Nothing needs to be displaced to admit its expansion.

I can tell by the look on your face--as I imagine it--that you aren't satisfied. So here's another way to think about the problem. Don't say that the universe is expanding. Insist that it remains fixed. Say instead that the things in the universe--galaxies, rulers, paper plates, Brooklyn (sorry, Mrs. Allen), atoms, people, Dukakis/Bentsen campaign buttons--are all shrinking. It's mathematically equivalent, right? But it doesn't require you to postulate that anything is "outside".

So why don't you have the same conceptual problem that you had when you viewed it the other (equivalent) way? Think about it.--Physicist

[samtheman]

Reminds me of an old episode of Dragnet called “The LSD Story” (I just looked it up) which opens up with a hippie in the park with his head stuck in a hole in the ground and Friday and Gannon tap him on the shoulder and he looks up and says, “wow, man, I can see to the center of the earth!”

[Lonesome in Massachussets]

I’d like to live on a planet orbiting the binary star Alcyone A, from a distance of about 10 AU, with two white dwarfs and a yellow sun orbiting outside of us and have an inside view of the Pleiades. Tides and seasons would be wild! The sky would be alive, both day and night.

[SunkenCiv]

Finite, yet unbounded. :') Thanks The Comedian.

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[SunkenCiv]

Thanks The Comedian.

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[Quix]

At least, I’d guess.

[Lonesome in Massachussets]

Named for Elbert Gary, of judiciary fame.

http://www.youtube.com/watch?v=0ILt3wNTZ7Q

[1010RD]

Excellent description. Thanks to both of you.

[AFPhys]

I came into this story very much too late - it having been posted nearly a month ago, I am still happy to have seen a ping to me for it.

I have long believed that the major reason for the artifice of “dark matter” and probably “dark energy” is precisely that the actual size of the universe is much greater than the currently “accepted” size. Thus, gravity from objects far out of our purview is tugging on the matter we are aware of, and affecting motions is a way that appears to be inexplicable with current beliefs. Though I have not studied the math sufficiently to be able to authoritatively check this, I have sufficient cosmology and math to state that this is a more than plausible description of reality. It may explain many of the current anomalies currently plaguing cosmology.

By the way, I did not come up with this thought - It was brought to me by a cosmologist in a seminar I attended over 15 years ago.