An infinitely repeating Universe would mean that someone could travel in a straight line and return to where they began. If our Universe were periodic like this, we would see repeating structures if we looked on large enough scales, as you can visualize in the image above.Nico Hamaus, Universitäts-Sternwarte München / The Ohio State University

Back when people thought the Earth was flat, it was almost heretical to suggest that traveling in a straight line for a long enough distance would eventually bring you back to your starting point. But it’s true: travel about 40,000 kilometers (or 25,000 miles) in any one direction — over the mountains, oceans and any other terrain you ran across — and return you would to where you began. It makes you wonder if space could be the same way. If you got in a rocket ship and traveled fast enough for long enough, and didn’t ruin things by colliding with a distant star or galaxy, could you eventually return to where you started?

A simulation of the structure of the Universe. If you leave one “edge” of the Universe and return through another, you just might live in a recurrent Universe.NASA, ESA, and E. Hallman (University of Colorado, Boulder)

It’s not as crazy as it sounds. We might think that the Universe is infinite, going on forever in all directions, but the evidence we have for the size and shape of the Universe is very much finite. For one, it’s only been 13.8 billion years since the Big Bang, and so we can only see the amount of space that 13.8 billion years of light traveling through the Universe and winding up where we are can illuminate. For another, there are hundreds of billions of galaxies, all appearing younger in the distant past the farther away we look. Is it possible that one (or more) of them is an infant version of the Milky Way we grew up in?

In a hypertorus model of the Universe, motion in a straight line will return you to your original location.ESO and deviantART user InTheStarlightGarden

Finally, could it be the case, just as the Earth has two dimensions we can move in on it (north-south and east-west, but not up-and-down), that the Universe might be a higher-dimensional structure like a hypersphere or a hypertorus where the various dimensions are closed and finite, curving back on themselves?

If that were the case, if you could travel in a straight line for long enough, you would wind up right back where you started. If you didn’t age, perhaps you could even wind up seeing the back of your own head just by looking for long enough, as your eyes would eventually encounter the light emitted from your own origin. If the Universe were like this, how would we figure it out?

A simulation of the large-scale structure of the Universe. Identification of one region of galaxies in one direction with identical galaxies in another would be evidence for a repeating Universe.Dr. Zarija Lukic

The key would be to look at the Universe on the largest scales and to look for locations where it appeared to have the same properties in different directions on the sky. A Universe that were finite and recurrent would imply that the same structures would appear over and over again in the Universe.

While most of the Universe would be difficult to identify as recurrent, since the finite speed-of-light means we’d be seeing the same objects at different stages in their evolution (like a younger Milky Way), there are always a slew of objects that would appear at the same stage of evolution at various locations. The large-scale structure of the Universe fails to show any structure like this, but there’s an even better place to look: the cosmic microwave background!

The fluctuations in the Cosmic Microwave Background, as seen by Planck. There is no evidence for any repeating structures on any scales or in any directions, even when the entire sky has been analyzed for them.ESA and the Planck collaboration

The fluctuations in the Big Bang’s leftover glow have a very particular pattern to them: they follow a bell-curve distribution, slightly larger in magnitude on larger scales than smaller ones, having been slightly processed by a few hundred thousand years of cosmic evolution before we observe them. But, despite the intricacies of that pattern, there’s something else: those fluctuations exhibit a random distribution of that particular pattern.

Many algorithms, generated by both humans and artificial intelligence, have been programmed to look for repetitive, non-random signals or for correlations between the fluctuations on various parts of the sky. If the Universe were finite and closed on itself — if parts of it repeated in other places — the cosmic microwave background would hold the evidence.

A visualization of a 3-torus model of space, where our observable Universe could be just a small portion of the overall structure.Bryan Brandenburg

We’ve searched exhaustively for it, and that evidence simply isn’t there. But the lack of such a detectable, repeating structure doesn’t necessarily mean that the Universe doesn’t have this type of topology. It only means that if the Universe does repeat, if it is a closed hypersurface, and if we could theoretically re-emerge in the same spot after traveling in a straight line for long enough, it is so on a scale that’s larger than the part we can observe. Given that we’re limited to how far light can travel in 13.8 billion years, there’s plenty of room for this to still be the case.

But there’s a catch.

Many of the galaxies shown here, in the Hubble eXtreme Deep Field (XDF) image, are beyond our current cosmic ability to reach, even at the speed of light. No galaxy ever observed has been determined to exist in disparate, opposite directions in the sky, which would be the sign that the Universe exhibited a closed, recurrent topology.NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

No matter how technologically advanced you imagine a human will someday be, so long as we’re limited by the speed of light we’ll never be able to find out, even if the Universe is really this way. Thanks to dark energy and the accelerated expansion of the Universe, it’s physically impossible to even reach all the way to the edge of today’s observable Universe; we can only get a third of the way there at maximum. Unless the Universe repeated on a scale that was less than about 15 billion light years in diameter today, we’d have no way to ever return to our original starting point by traveling in a straight line.

The size of our visible Universe (yellow), along with the amount we can reach (magenta). We might not ever be able to return to our starting point in a Universe containing dark energy, but perhaps in principle the Universe still folds back on itself.E. Siegel, based on work by Wikimedia Commons users Azcolvin 429 and Frédéric MICHEL

However, that doesn’t mean it isn’t possible for the Universe to be closed, finite, and for it to fold in on itself the way a Hypersphere or a Three-Torus does. It just means that the expansion of the Universe — accelerating as it is — forbids us from ever completing a single “circumnavigation” of the Universe and returning to our origin. Because of the combination of:

  • the finite age of the Universe,
  • the finite speed of light,
  • the expansion of the Universe and
  • the presence of dark energy,

we may never be able to know whether our Universe is infinite or not, and what its true topology is. We can only see what we have access to, and that doesn’t appear to be enough to be decisive concerning scales larger than what we can observe.

The appearance of different angular sized of fluctuations in the CMB results in different spatial curvature scenarios. Presently, the Universe appears to be flat, but we have only measured down to about the 1% level. At a more precise level, we may discover some level of intrinsic curvature, after all.Smoot group at Lawrence Berkeley Labs

All we can see is the part of the Universe accessible to us, which allows us to place constraints on what its topology is allowed to be. As far as we can tell, it’s flat, non-repeating and possibly (but not necessarily) infinite. Perhaps, as time goes on, and more of the Universe slowly reveals itself to us, or as our curvature measurements get more precise, we’ll discover a departure from what we’ve concluded so far. After all, we’re limited by what we’re capable of observing, but those limits will continue to change as the Universe ages. The possibility of a Universe that’s vastly different from what we’ve concluded thus far might lie just beyond the cosmic horizon.

” readability=”124″>
< div _ ngcontent-c15 ="" innerhtml ="

A considerably duplicating Universe would indicate that somebody might take a trip in a straight line and go back to where they started. If our Universe were regular like this, we would see duplicating structures if we searched big sufficient scales, as you can imagine in the image above. Nico Hamaus, Universitäts-Sternwarte München/ The Ohio State University

Back when individuals believed the Earth was flat, it was practically heretical to recommend that taking a trip in a straight line for a long sufficient range would ultimately bring you back to your beginning point. However it holds true: take a trip about 40,000 kilometers( or25,000 miles) in any one instructions– over the mountains, oceans and any other surface you stumbled upon– and return you would to where you started. It makes you question if area might be the very same method. If you got in a space rocket and took a trip quickly enough for enough time, and didn’t mess up things by hitting a far-off star or galaxy, could you ultimately go back to where you began? (************ )

(**************** )(**** )

A

simulation of the structure of deep space.
If you leave one “edge” of deep space and return through another, you simply may reside in a frequent Universe. NASA, ESA, and E. Hallman( University of Colorado, Stone)

It

‘s not as insane as it sounds. We may believe that deep space is unlimited, going on permanently in all instructions, however the proof we have for the shapes and size of deep space is quite limited. For one, it’s just been138 billion years because the Big Bang, therefore we can just see the quantity of area that138 billion years of light taking a trip through deep space and ending up where we are can light up. For another, there are numerous billions of galaxies, all appearing more youthful in the remote past the further away we look. Is it possible that a person( or more )of them is a baby variation of the Galaxy we matured in?

(************ )(***************** )

In a hypertorus design of deep space, movement
in a straight line will return you to your initial area. ESO and deviantART user InTheStarlightGarden

Lastly, could

it hold true, simply as the Earth has 2 measurements we can move in on it (north-south and east-west, however not up-and-down), that deep space might be a higher-dimensional structure like a hypersphere or a hypertorus where the different measurements are closed and limited, curving back on themselves?

If that held true, if you might take a trip in a straight line for enough time, you would end up right back where you began. If you didn’t age, maybe you might even end up seeing the back of your own head simply by trying to find enough time, as your eyes would ultimately experience the light given off from your own origin. If deep space resembled this, how would we figure it out?

A simulation of the massive structure of deep space. Recognition of one area of galaxies in one instructions with similar galaxies in another would be proof for a duplicating Universe. Dr. Zarija Lukic

The secret would be to take a look at deep space on the biggest scales and to try to find places where it appeared to have the very same residential or commercial properties in various instructions on the sky. A Universe that were limited and reoccurring would indicate that the very same structures would appear over and over once again in deep space.

While the majority of deep space would be tough to recognize as reoccurring, because the limited speed-of-light ways we ‘d be seeing the very same things at various phases in their development (like a more youthful Galaxy), there are constantly a variety of things that would appear at the very same phase of development at different places. The massive structure of deep space stops working to reveal any structure like this, however there’s an even much better location to look: the cosmic microwave background!

The changes in the Cosmic Microwave Background, as seen by Planck. There is no proof for any duplicating structures on any scales or in any instructions, even when the whole sky has actually been evaluated for them. ESA and the Planck partnership

The changes in the Big Bang’s remaining radiance have an extremely specific pattern to them: they follow a bell-curve circulation, somewhat bigger in magnitude on bigger scales than smaller sized ones, having actually been somewhat processed by a couple of hundred thousand years of cosmic development prior to we observe them. However, regardless of the complexities of that pattern, there’s something else: those changes display a random circulation of that specific pattern.

Lots of algorithms, created by both people and expert system, have actually been set to try to find repeated, non-random signals or for connections in between the changes on different parts of the sky. If deep space were limited and closed on itself– if parts of it duplicated in other locations– the cosmic microwave background would hold the proof.

A visualization of a 3-torus design of area, where our observable Universe might be simply a little part of the general structure. Bryan Brandenburg

We have actually browsed extensively for it, which proof just isn’t there. However the absence of such a noticeable, duplicating structure does not always indicate that deep space does not have this kind of geography. It just implies that if deep space does repeat, if it is a closed hypersurface, and if we might in theory reappear in the very same area after taking a trip in a straight line for enough time, it is so on a scale that’s bigger than the part we can observe. Considered that we’re restricted to how far light can take a trip in 13.8 billion years, there’s lots of space for this to still hold true.

However there’s a catch.

Much of the galaxies revealed here, in the Hubble eXtreme Deep Field (XDF) image, are beyond our present cosmic capability to reach, even at the speed of light. No galaxy ever observed has actually been figured out to exist in diverse, opposite instructions in the sky, which would be the indication that deep space showed a closed, reoccurring geography. NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

No matter how highly advanced you envision a human will sooner or later be, so long as we’re restricted by the speed of light we’ll never ever have the ability to learn, even if deep space is actually in this manner. Thanks to dark energy and the sped up growth of deep space, it’s physically difficult to even reach all the method to the edge these days’s observable Universe; we can just get a 3rd of the method there at optimum. Unless deep space duplicated on a scale that was less than about 15 billion light years in size today, we ‘d have no chance to ever go back to our initial beginning point by taking a trip in a straight line.

The size of our noticeable Universe (yellow), together with the quantity we can reach (magenta). We may never have the ability to go back to our beginning point in a Universe consisting of dark energy, however maybe in concept deep space still folds back on itself. E. Siegel, based upon work by Wikimedia Commons users Azcolvin 429 and Frédéric MICHEL

Nevertheless, that does not indicate it isn’t possible for deep space to be closed, limited, and for it to fold in on itself the method a Hypersphere or a Three-Torus does. It simply implies that the growth of deep space– speeding up as it is– prohibits us from ever finishing a single “circumnavigation” of deep space and going back to our origin. Due to the fact that of the mix of:

  • the limited age of deep space,
  • the limited speed of light,
  • the growth of deep space and
  • the existence of dark energy,

we might never ever have the ability to understand whether our Universe is unlimited or not, and what its real geography is. We can just see what we have access to, which does not seem sufficient to be definitive worrying scales bigger than what we can observe.

The look of various angular sized of changes in the CMB leads to various spatial curvature situations. Currently, deep space seems flat, however we have actually just determined to about the 1% level. At a more exact level, we might find some level of intrinsic curvature, after all. Smoot group at Lawrence Berkeley Labs

All we can see is the part of deep space available to us, which enables us to position restraints on what its geography is enabled to be. As far as we can inform, it’s flat, non-repeating and potentially (however not always) infinite. Maybe, as time goes on, and more of deep space gradually exposes itself to us, or as our curvature measurements get more exact, we’ll find a departure from what we have actually concluded up until now. After all, we’re restricted by what we can observing, however those limitations will continue to alter as deep space ages. The possibility of a Universe that’s greatly various from what we have actually concluded so far may lie simply beyond the cosmic horizon.

” readability =”124″ >

.

.

A considerably duplicating Universe would indicate that somebody might take a trip in a straight line and go back to where they started. If our Universe were regular like this, we would see duplicating structures if we searched big sufficient scales, as you can imagine in the image above. Nico Hamaus, Universitäts-Sternwarte München/ The Ohio State University

.

.

Back when individuals believed the Earth was flat, it was practically heretical to recommend that taking a trip in a straight line for a long sufficient range would ultimately bring you back to your beginning point. However it holds true: take a trip about 40, 000 kilometers (or 25, 000 miles) in any one instructions– over the mountains, oceans and any other surface you stumbled upon– and return you would to where you started. It makes you question if area might be the very same method. If you got in a space rocket and took a trip quickly enough for enough time, and didn’t mess up things by hitting a far-off star or galaxy, could you ultimately go back to where you began?

.

.

A simulation of the structure of deep space. If you leave one “edge” of deep space and return through another, you simply may reside in a frequent Universe. NASA, ESA, and E. Hallman (University of Colorado, Stone)

.

.

It’s not as insane as it sounds. We may believe that deep space is unlimited, going on permanently in all instructions, however the proof we have for the shapes and size of deep space is quite limited. For one, it’s just been 13.8 billion years because the Big Bang, therefore we can just see the quantity of area that 13.8 billion years of light taking a trip through deep space and ending up where we are can light up. For another, there are numerous billions of galaxies, all appearing more youthful in the remote past the further away we look. Is it possible that a person (or more) of them is a baby variation of the Galaxy we matured in?

.

.

In a hypertorus design of deep space, movement in a straight line will return you to your initial area. ESO and deviantART user InTheStarlightGarden

.

.

Lastly, could it hold true, simply as the Earth has 2 measurements we can move in on it (north-south and east-west, however not up-and-down), that deep space might be a higher-dimensional structure like a hypersphere or a hypertorus where the different measurements are closed and limited, curving back on themselves?

If that held true, if you might take a trip in a straight line for enough time, you would end up right back where you began. If you didn’t age, maybe you might even end up seeing the back of your own head simply by trying to find enough time, as your eyes would ultimately experience the light given off from your own origin. If deep space resembled this, how would we figure it out?

.

.

A simulation of the massive structure of deep space. Recognition of one area of galaxies in one instructions with similar galaxies in another would be proof for a duplicating Universe. Dr. Zarija Lukic

.

.

The secret would be to take a look at deep space on the biggest scales and to try to find places where it appeared to have the very same residential or commercial properties in various instructions on the sky. A Universe that were limited and reoccurring would indicate that the very same structures would appear over and over once again in deep space.

While the majority of deep space would be tough to recognize as reoccurring, because the limited speed-of-light ways we ‘d be seeing the very same things at various phases in their development (like a more youthful Galaxy), there are constantly a variety of things that would appear at the very same phase of development at different places. The massive structure of deep space stops working to reveal any structure like this, however there’s an even much better location to look: the cosmic microwave background!

.

.

The changes in the Cosmic Microwave Background, as seen by Planck. There is no proof for any duplicating structures on any scales or in any instructions, even when the whole sky has actually been evaluated for them. ESA and the Planck partnership

.

.

The changes in the Big Bang’s remaining radiance have an extremely specific pattern to them: they follow a bell-curve circulation, somewhat bigger in magnitude on bigger scales than smaller sized ones, having actually been somewhat processed by a couple of hundred thousand years of cosmic development prior to we observe them. However, regardless of the complexities of that pattern, there’s something else: those changes display a random circulation of that specific pattern.

Lots of algorithms, created by both people and expert system, have actually been set to try to find repeated, non-random signals or for connections in between the changes on different parts of the sky. If deep space were limited and closed on itself– if parts of it duplicated in other locations– the cosmic microwave background would hold the proof.

.

.

A visualization of a 3-torus design of area, where our observable Universe might be simply a little part of the general structure. Bryan Brandenburg

.

.

We have actually browsed extensively for it, which proof just isn’t there. However the absence of such a noticeable, duplicating structure does not always indicate that deep space does not have this kind of geography. It just implies that if deep space does repeat, if it is a closed hypersurface, and if we might in theory reappear in the very same area after taking a trip in a straight line for enough time, it is so on a scale that’s bigger than the part we can observe. Considered that we’re restricted to how far light can take a trip in 13.8 billion years, there’s lots of space for this to still hold true.

However there’s a catch.

.

.

Much of the galaxies revealed here, in the Hubble eXtreme Deep Field (XDF) image, are beyond our present cosmic capability to reach, even at the speed of light. No galaxy ever observed has actually been figured out to exist in diverse, opposite instructions in the sky, which would be the indication that deep space showed a closed, reoccurring geography. NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

.

.

No matter how highly advanced you envision a human will sooner or later be, so long as we’re restricted by the speed of light we’ll never ever have the ability to learn, even if deep space is actually in this manner. Thanks to dark energy and the sped up growth of deep space, it’s physically difficult to even reach all the method to the edge these days’s observable Universe; we can just get a 3rd of the method there at optimum. Unless deep space duplicated on a scale that was less than about 15 billion light years in size today, we ‘d have no chance to ever go back to our initial beginning point by taking a trip in a straight line.

.

.

The size of our noticeable Universe (yellow), together with the quantity we can reach (magenta). We may never have the ability to go back to our beginning point in a Universe consisting of dark energy, however maybe in concept deep space still folds back on itself. E. Siegel, based upon work by Wikimedia Commons users Azcolvin 429 and Frédéric MICHEL

.

.

Nevertheless, that does not indicate it isn’t possible for deep space to be closed, limited, and for it to fold in on itself the method a Hypersphere or a Three-Torus does. It simply implies that the growth of deep space– speeding up as it is– prohibits us from ever finishing a single “circumnavigation” of deep space and going back to our origin. Due to the fact that of the mix of:

    .

  • the limited age of deep space,
  • the limited speed of light,
  • the growth of deep space and
  • the existence of dark energy,

.

we might never ever have the ability to understand whether our Universe is unlimited or not, and what its real geography is. We can just see what we have access to, which does not seem sufficient to be definitive worrying scales bigger than what we can observe.

.

.

The look of various angular sized of changes in the CMB leads to various spatial curvature situations. Currently, deep space seems flat, however we have actually just determined to about the 1 % level. At a more exact level, we might find some level of intrinsic curvature, after all. Smoot group at Lawrence Berkeley Labs

.

.

All we can see is the part of deep space available to us, which enables us to position restraints on what its geography is enabled to be. As far as we can inform, it’s flat, non-repeating and potentially (however not always) infinite. Maybe, as time goes on, and more of deep space gradually exposes itself to us, or as our curvature measurements get more exact, we’ll find a departure from what we have actually concluded up until now. After all, we’re restricted by what we can observing, however those limitations will continue to alter as deep space ages. The possibility of a Universe that’s greatly various from what we have actually concluded so far may lie simply beyond the cosmic horizon.

.