# What is the size of the universe.is it infinite?

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What is the exact size of the universe.is it infinite?

"No one knows if the universe is infinitely large, or even if ours is the only universe that exists." - NASA

Still, the "observable universe" is a sphere roughly 92 billion light-years in diameter.

This isn't quite a question from metaphysics (i.e., beyond scientific enquiry) but it is close to it and so therefore very difficult to answer - especially in "exact" terms.

First of all, we can begin with a discussion of what you mean by "the Universe". Of course, by dictionary definition "the Universe" is everything, but it may be that we exist as a "bubble" inside a bigger Universe - the bigger Universe shares some common physical laws with ours but many physical constants (and hence behaviours) could be different and so that which we think of as "the Universe" might just be one little fragment.

For instance, in the "eternal inflation" cosmology - which is highjly regarded scientifically, our "universe" is in a different quantum phase from an infinite surrounding universe - and there are an infinitre number of similar "universes" to ours.

Alternatively, we could be in a sole Universe, which began with the Big Bang some 14 or so billion years ago and has been expanding ever since. But it might be that the Big Bang was the result of some interaction between some other physical aspects of a "higher" universe and so on…

Designing experiments to test these theories is tough, though not quite impossible. But as of today the answer to your question is either "opinions vary" or "we do not know".

## Does the Universe have finite or infinite size?

Not necessarily. If the universe is currently bounded (finite), it will have been very tiny at the time of the early Big Bang. But if it is currently unbounded (infinite) then it will have always been infinite - no matter how far we go back in time.

At least, that's the implication of the currently accepted cosmological theories.

Whether the universe is bounded or unbounded is unknown.

Although this thread is 18 months old, the same point seems to recur, as in #48 of

I am wondering if it is possible for us to agree that some aspects of science are "known", and the remainder aspects cannot be known ever.
Category 1: Knowable and known. Example: For phenomena taking place over extremely large spaces, General Relativity produces more accurate predictions than Newtonian physics.
Category 2: Unknown and unknowable. Example: Is the universe finite or infinite?

With respect to example (2), it will generally be possible as time passes to have some degree of confidence greater than 0.5 that (a) the universe is more likely to be finite, or (b) more likely to be infinite. If I remember correctly from past reading, there was no time during the past 100 years during which the general scientific consensus was (a). Since the early 20th century it has always been (b) or undecided. The confidence level will never be 100% for any category 2 knowledge.

I found the following 2005 paper which gives a basis for calculating a probability that the universe is infinite.

My research skills are not very good, and I have not been able to find more recent corresponding data.

So, can we agree that it is OK to say that based on the 2005 data used in the cited paper, (1) the best probability estimate that universe is infinite is 84%, and (2) that no matter how much better new data becomes, this estimate will never become 100%?

## If the universe is truly infinite in size.

The universe could have started at an infinite size. There is no problem with that model. If it is infinite now it was infinite as long as it existed. We don't know if it is.

First thing you should notice or consider that big bang did not happened at a point but it happened everywhere in the universe.

Think an infinite size of paper and in this paper you are using grid coordinates. Let's suppose you choosed the distance between every point on this grid to be ##D##.

While we go back in time, this distance (##D##) becomes smaller and smaller. Now lets go back in time, 0.000000000000001 seconds after the big bang. At this moment the distance between two points will be very small but universe would be still infinite.

Where at the big bang the distance was ##0## between two points, but also universe was infinite in size. Its hard to imagine yes, but its also what we mean by "big bang happened everywhere", cause all (infinite) universe was at that point while the distance was 0 between each point, which we call that point singularity.

You cannot extrapolate all the way back to the singularity. No coordinate chart for any portion of the universe goes that far. That's part of what it means to be a "singularity".

A singularity is not a point.

You cannot extrapolate all the way back to the singularity. No coordinate chart for any portion of the universe goes that far. That's part of what it means to be a "singularity".

A singularity is not a point.

The following is, at best, a "B" response to your "I" thread.

The switch you might make is to think of the universe as getting denser and denser as you roll the clock back - NOT smaller and smaller. Then perhaps you ask what is the universe expanding into if it was always infinitely large and its now somehow getting less dense without losing any particles, which is a different visualization problem, but at least its one that is more aligned with what expansion theories are saying about the past universe.

My own thinking on this is not at all visual. Infinities need not be of the same count. There are an infinite count of odd integers, and an infinite count of even integers, and obviously the count of all integers is twice that of either only odds or only evens. That doesn't help me visualize anything, but it helps me get to accepting that something being infinite does not mean it cannot possibly still be "more" than it is.

A visualization I found useful first grappling with these ideas is to imagine an infinite space at a moment in cosmological time as being chopped into one inch cubes. You have a (countably) infinite collection of these cubes. A bit later, all the cubes are two inches on a side. They still just assemble into an infinite space. Now start compressing then to smaller cubes. No matter how many time you reduce all the cube sizes by half, they still assemble into an infinite space. As noted by @jbriggs444, you cannot take this process all the way back to zero size cubes.

For me, at the beginning, this notion of a magical infinite bag of cubes that grow or shrink, made the whole thing more mentally palatable. It sidesteps the mental block of what is the expansion into, and helps pull away from the idea of ‘how does everything grow without getting in each other’s way.

That's just Zeno's paradox in another form. Imagining that for something to get to ##0## it must halve an infinite number of times and can never get there.

Mathematically, you can easily have a (distance) function that continuously reduces to ##0## in finite time. For example, for a matter dominated universe the function could be ##a(t) = (t/t_0)^<2/3>##. That function, mathematically, quite happily goes to ##0## at ##t = 0##. Even more simply the linear function ##a(t) = t## would do the same.

At ##t=0## the distance between any two points would be ##0##. Mathematically that's not an issue, per se. At every time except ##t=0## you have a valid metric and at ##t=0## the metric is gone!

The real issue is the physical interpretation of this: which might be that distance as a physically measurable quantity has ceased to exist. Could you could interpret that as that "space" has ceased to exist? Also, as the distance between any two points reduces towards ##0##, the density increases without bound. And, at ##t=0##, the density is either "infinite" or more precisely "undefined".

Most people seem to visualise the expansion as leading back to a single point. This appeals to the physical and mathematical notion that:

##x = y## if and only the distance between ##x## and ##y## is ##0##. In other words, if the distance between any two points is zero, then you have only one point.

But, mathematically, if you consider ##mathbb^3##, say, without a well-defined metric, then it's just the same old infinite set of points but without the concept of distance.

Another way to visualise the singularity, therefore, is to imagine the underlying set of points staying exactly where they are, but this thing we call and measure distance reduces until at ##t=0## the concept of distance itself has gone. And, the problem is that we have no description of the laws of physics that would support this process all the way back to ##t=0##.

## Strange but True: Infinity Comes in Different Sizes

In the 1995 Pixar film Toy Story, the gung ho space action figure Buzz Lightyear tirelessly incants his catchphrase: "To infinity &hellip and beyond!" The joke, of course, is rooted in the perfectly reasonable assumption that infinity is the unsurpassable absolute&mdashthat there is no beyond.

That assumption, however, is not entirely sound. As German mathematician Georg Cantor demonstrated in the late 19th century, there exists a variety of infinities&mdashand some are simply larger than others.

Take, for instance, the so-called natural numbers: 1, 2, 3 and so on. These numbers are unbounded, and so the collection, or set, of all the natural numbers is infinite in size. But just how infinite is it? Cantor used an elegant argument to show that the naturals, although infinitely numerous, are actually less numerous than another common family of numbers, the "reals." (This set comprises all numbers that can be represented as a decimal, even if that decimal representation is infinite in length. Hence, 27 is a real number, as is &pi, or 3.14159&hellip.)

In fact, Cantor showed, there are more real numbers packed in between zero and one than there are numbers in the entire range of naturals. He did this by contradiction, logically: He assumes that these infinite sets are the same size, then follows a series of logical steps to find a flaw that undermines that assumption. He reasons that the naturals and this zero-to-one subset of the reals having equally many members implies that the two sets can be put into a one-to-one correspondence. That is, the two sets can be paired so that every element in each set has one&mdashand only one&mdash"partner" in the other set.

Think of it this way: even in the absence of numerical counting, one-to-one correspondences can be used to measure relative sizes. Imagine two crates of unknown sizes, one of apples and one of oranges. Withdrawing one apple and one orange at a time thus partners the two sets into apple-orange pairs. If the contents of the two crates are emptied simultaneously, they are equally numerous if one crate is exhausted before the other, the one with remaining fruit is more plentiful.

Cantor thus assumes that the naturals and the reals from zero to one have been put into such a correspondence. Every natural number n thus has a real partner rn. The reals can then be listed in order of their corresponding naturals: r1, r2, r3, and so on.

Then Cantor's wily side begins to show. He creates a real number, called p, by the following rule: make the digit n places after the decimal point in p something other than the digit in that same decimal place in rn. A simple method would be: choose 3 when the digit in question is 4 otherwise, choose 4.

For demonstration's sake, say the real number pair for the natural number 1 (r1) is Ted Williams's famed .400 batting average from 1941 (0.40570&hellip), the pair for 2 (r2) is George W. Bush's share of the popular vote in 2000 (0.47868&hellip) and that of 3 (r3) is the decimal component of &pi (0.14159&hellip).

Now create p following Cantor's construction: the digit in the first decimal place should not be equal to that in the first decimal place of r1, which is 4. Therefore, choose 3, and p begins 0.3&hellip. Then choose the digit in the second decimal place of p so that it does not equal that of the second decimal place of r2, which is 7 (choose 4 p = 0.34&hellip). Finally, choose the digit in the third decimal place of p so that it does not equal that of the corresponding decimal place of r3, which is 1 (choose 4 again p = 0.344&hellip).

Continuing down the list, this mathematical method (called "diagonalization") generates a real number p between zero and one that, by its construction, differs from every real number on the list in at least one decimal place. Ergo, it cannot be on the list.

In other words, p is a real number without a natural number partner&mdashan apple without an orange. Thus, the one-to-one correspondence between the reals and the naturals fails, as there are simply too many reals&mdashthey are "uncountably" numerous&mdashmaking real infinity somehow larger than natural infinity.

"The idea of being 'larger than' was really a breakthrough," says Stanley Burris, professor emeritus of mathematics at the University of Waterloo in Ontario. "You had this basic arithmetic of infinity, but no one had thought of classifying within infinity&mdashit was just kind of a single object before that."

Adds mathematician Joseph Mileti of Dartmouth College: "When I first heard the result and first saw it, it was definitely something that knocked me over. It's one of those results that's short and sweet and really, really surprising."

## &ldquoThe Hitchhiker's Guide to the Galaxy's definition of "Universe":

The Universe is a very big thing that contains a great number of planets and a great number of beings. It is Everything. What we live in. All around us. The lot. Not nothing. It is quite difficult to actually define what the Universe means, but fortunately the Guide doesn't worry about that and just gives us some useful information to live in it.

Area: The area of the Universe is infinite.

Imports: None. This is a by product of infinity it is impossible to import things into something that has infinite volume because by definition there is no outside to import things from.

Exports: None, for similar reasons as imports.

Population: None. Although you might see people from time to time, they are most likely products of your imagination. Simple mathematics tells us that the population of the Universe must be zero. Why? Well given that the volume of the universe is infinite there must be an infinite number of worlds. But not all of them are populated therefore only a finite number are. Any finite number divided by infinity is zero, therefore the average population of the Universe is zero, and so the total population must be zero.

Art: None. Because the function of art is to hold a mirror up to nature there can be no art because the Universe is infinite which means there simply isn't a mirror big enough.

Sex: None. Although in fact there is quite a lot, given the zero population of the Universe there can in fact be no beings to have sex, and therefore no sex happens in the Universe.&rdquo

## If the size of the universe is infinite and the speed of light is constant, are there places light has not reached?

Despite a century of hard work by many great geniuses, the large-scale structure of the universe is still not completely understood. Nevertheless, we can try to speculate intelligently on the nature of the entire universe.

There are important observational facts which are not in dispute. When we look out as far as possible with our best telescopes, we observe a universe which is homogeneous, expanding according to Hubble's Law, and filled with cosmic microwave background radiation. It is not known if the homogeneity we observe within about 12 billion light-years of the earth extends all the way to infinity. If it does, then there is no part of the universe which lacks light, matter, or galaxies. This means that the hot, dense, big-bang beginning of our universe occurred everywhere throughout all of infinite space. There was no empty place for light to travel to.

The universe has a finite age, so it is certainly true light has traveled only a finite distance since the big-bang. Undoubtedly there are remote objects in the universe which have sent light in our direction and that light has not yet arrived. Indeed, that light may never arrive if the expansion rate of the universe does not slow down. Recent evidence indicates the expansion rate of the universe is actually accelerating. This has an army of cosmologists working overtime, trying to understand it. If the universe is accelerating, then we will never get to see most of it. Even objects that we can now see will disappear as they recede beyond the speed of light.
Answered by: Hugh Mongus, M.S., Retired teacher

'The greatest good will come from the technical improvements tending to unification and harmony.'

## How big is the universe?

Our best estimates put the observable universe at about 93 billion light-years across 8.8×10 23 kilometers. The real size, however, is probably much greater.

### Observing the universe — parallax and beyond

Let’s start our foray into the size of the universe with a very simple experiment: place your palm in front of your eyes. Look at it and focus on its position. Then close one eye, look at the palm again, and then switch eyes. Your hand appears to slightly move sideways, because of the different position of your eyes — this is called parallax.

By knowing the distance between your eyes and seeing the apparent displacement of your hand, we can calculate the distance to your hand. Now, imagine that instead of your eyes, we have two telescopes out in space, and instead of your palm we have a very distant object, say a star. We know how far apart the two telescopes are so we can calculate the distance to the star through parallax.

Thanks to the Earth’s orbit (which we can calculate precisely), we have exactly that: the ability to observe the same thing from two different points (the same telescope, moved around by the Earth’s orbit). This approach is used routinely by astronomers to calculate the distance to celestial objects.

A simplified illustration of the parallax of an object against a distant background due to a perspective shift. When viewed from “Viewpoint A”, the object appears to be in front of the blue square. When the viewpoint is changed to “Viewpoint B”, the object appears to have moved in front of the red square. Image credits: Booyabazooka / Wikipedia.

However, after around 100 light years, the distance becomes simply too great and the parallax method starts to lose its efficiency. Still, through parallax, we know that the universe is at the very least 200 light years across (100 in both directions) — something which at one point, seemed inconceivably large.

The real size, however, goes far beyond that.

### The observable universe — and a standard candle

This is where things start to get really interesting (and tricky). Let’s think about the age of the universe for a moment. When we look at something that’s 1 light year away, it took the light one year to get from that object to us, so we’re seeing it the way it was one year ago. In a way, we’re looking through time and seeing the past. We’ve seen galaxies that are over billions of years old, so the size of the universe must be at least a few billion light years across.

To finesse things, we know the age of the universe, within a pretty good margin, to be 13.7-13.8 billion years, and we know that from two crucial pieces of evidence.

The first one has to do with universal expansion. We know that the universe is expanding, and it’s expanding at an accelerating rate. Assuming that it’s expanding similarly in all parts of the universe (which most scientists agree), all the objects in the universe are moving apart from one another at a similar pace. Let’s take the galaxies, as incredibly massive “objects”: we know that they’re moving apart, and by knowing their current speeds and distances, as well as the rate at which the universal expansion is accelerating, we can calculate how long it took them to reach their current position. This method puts the age of the universe at around 14 billion years.

RS Puppis is one of the brightest known Cepheid variable stars in the Milky Way — which makes it one of the most important “standard candles”. Image credits: Hubble / NASA.

The second method relies on measuring the age of the oldest clusters we’ve been able to observe. This is not straightforward and makes extensive use of our knowledge of stellar formation, particularly a group of stars called “main sequence stars”, which are the most common type of stars. We know that these stars change color in time, becoming redder as they age. By measuring their color and brightness, we can calculate their age — they are a “standard candle”, an object whose brightness we can calculate mathematically. But for the very oldest stars, even this doesn’t really work, and this is where the work of Henrietta Swan Leavitt, an American astronomer, comes in. Back in 1908, Henrietta realized that there was a special class of stars called Cepheid variables. These stars have highly reliable brightness and pulsations, which enables astronomers to calculate just how old these stars are. Using this method, the age of the universe was calculated to be 13.7 billion years.

The fact that the two methods come up with such close values is encouraging, and subsequent studies and models have confirmed and refined this range. Currently, scientists are confident (99.1% accuracy) that the age of the universe is 13.81 billion years — meaning we have another important milestone in our quest to figure out the size of the universe.

So we have a smaller “yardstick” to measure things in our cosmic neighborhood, and a larger one to measure things in the observable universe. What’s next?

### The size of the observable universe

We might think that the size of the observable universe is 13.7 billion light years in all directions, so 27.4 billion light-years across. Spoiler alert: that’s not true! That’s just what we can see now — during the time it took the light to travel to us, the universe has continued to expand. Keep in mind: space itself is increasing.

Visualization of the expansion of the Universe. Image credits: Eugenio Bianchi, Carlo Rovelli & Rocky Kolb.

### Comoving and proper distances

At this point, we should differentiate between the two distances.

Proper distance is essentially where a distant object would be at a specific moment of cosmological time. This can change over time due to the expansion of the universe.

Comoving distance factors out the expansion of the universe, giving a distance that does not change in time due to the expansion of space but can change, for instance, due to galactic movement.

The Universe’s expansion results in the proper distance changing, while the comoving distance is unchanged by this expansion.

So how big has the observable universe become since its inception?

The best answer we have comes from something called redshift. When a source of light comes from very far away, its wavelength starts to shift towards the red side of the spectrum. This type of Doppler shift was a key indication that the size of the universe is increasing, and can help researchers estimate how much the universe has expanded.

Basically, if we were to find some really old photons and analyze their spectral shift, we’d have a good estimate of how old something is, and how far away it currently lies. The earliest photons we have come from the so-called cosmic microwave background (CMBR), faint cosmic background radiation filling all space which represents the earliest known electromagnetic radiation.

Some of our most accurate estimates of the CMBR come from the Wilkinson Microwave Anisotropy Probe (WMAP), which, along with other estimates, found that farthest observable photons come from 46.5 billion light-years away.

The Cosmic Microwave Background temperature fluctuations from the 7-year Wilkinson Microwave Anisotropy Probe data seen over the full sky as a celestial sphere. Image credits: NASA.

The comoving distance from Earth to the edge of the observable universe is about 46.5 billion light-years 14.26 (gigaparsecs or 4.40×10 26 meters) in any direction. So, although the light itself might have only traveled for 13.8 billion years, the distance from us to the point it came from is, at present, 46 billion light years away.

This would make the diameter of the observable universe about 93 billion light-years (the equivalent of 28 billion parsecs), assuming that the Earth occupies a relatively central position in the universe.

It should be noted that at the current time, the proper and the comoving distance between the Earth and the edge of the observable universe are defined as equal (for the sake of simplicity). This is merely a convention — at other times, the scale factor was different than 1.

The same measurements described above concluded that at the time the CMBR was emitted, the proper distance was only 42 million light-years.

Another visualization of the universal expansion. Image credits: NASA, Goddard Space Flight Center.

So, to the best of our knowledge, the size of the observable universe is 93 billion light-years across. It is almost certainly bigger than that, but we don’t have any substantial evidence to judge its size outside of that.

However, one statistical estimate carried out by Oxford researchers found that the universe might be 251 times larger than the observable universe, which would put it at 23343 light-years across. That’s truly humbling, and some studies go even beyond that. Estimates for the total size of the universe, reach as high as megaparsecs, as implied by one resolution of the No-Boundary Proposal. Just so you can get an idea of how big that number is, it doesn’t even matter what units of measure you express it in — whether it be nanometers or megaparsecs, the difference would simply get lost in the irrelevant final digits.

### Universal expansion

Universal expansion can be very difficult to wrap your head around, but here’s an easy analogy to help you visualize things.

Think of the universe as a muffin dough. Think of matter inside this space as poppy seeds inside this dough. As the dough is baked, it expands, and the space between all poppy seeds increases — similarly, universal expansion drives matter apart, though the process is only detectable at cosmological scales.

### The shape of the universe

Now, we have some idea of how big the universe is — or rather, we have a lower limit to how big the universe is — but what does it look like?

Most people would probably imagine the universe to be somewhat spherical in shape. Although intuition is hardly reliable in cosmology, a spherical universe is entirely plausible. In General Relativity, space-time is curved, which would imply that there are three possible shapes of the universe:

• flat (zero curvature)
• spherical or closed (positive curvature) or
• hyperbolic or open (negative curvature).

There are also other, more complex shapes which have been proposed, such as a Moebius Strip or its 3D correspondent, a Klein Bottle — where there is no inside or outside, only one surface.

However, more recent evidence suggests that the universe is essentially flat. Temperature measurements of the above-mentioned CMBR would exhibit substantial variations if the universe was curved, but to the best of our ability, we haven’t been able to spot any such variations, which indicates that, to an acceptable range, the universe is essentially flat.

If the universe is indeed “flat”, the math behind General Relativity and universal expansion indicates that it will continue to expand forever, though it’s not clear if this expansion will continue to accelerate indefinitely or will slow down.

However, this doesn’t really tell us anything about how big the universe really is, and there’s an even more puzzling possibility: perhaps the universe is so big that the fraction represented by our observable universe isn’t big enough to exhibit its curvature, much like from our personal perspective, the Earth seems flat, but if you zoom out sufficiently, its curvature becomes evident.

This leaves another important question to discuss.

### Is the universe infinite?

Since we can’t exactly figure out how big the universe is, another possibility emerges: that of an infinite universe.

The two possibilities (of a finite or an infinite universe) raise equally puzzling situations: if the universe is finite, then what could possibly be outside of it, and what exactly is the universe expanding into? Is the universe creating space? Does that question even make sense?

If the universe is infinite, things get even weirder. How can something that’s not infinitely old be infinitely vast? Can an infinite universe expand? In theory, yes — although it’s very difficult to visualize (and makes the math and physics much trickier). Again, think of the universal expansion not as an “expansion”, but rather a “stretch”, in which all parts of the universe, from the very middle to the periphery, are being pulled apart from each other. But does an infinite universe contain all possible configurations of matter? Is there another you somewhere in the universe? Or even better, is there a version of you that’s immortal, doesn’t need sleep and has cat ears? That is the kind of problem which might emerge from an infinite universe.

### Pi and an infinite universe

A more straightforward issue with an infinite universe is represented by Olbers’ paradox, which states that the darkness of the night sky conflicts with the assumption of an infinite and eternally static universe: if it were truly infinite, then every single bit of the night sky would eventually fall on to a star and would light up, until all the night sky is lit up. Since that doesn’t happen, then the universe isn’t infinite.

As more distant stars are revealed in this animation depicting an infinite, homogeneous and static universe, they fill the gaps between closer stars. Since the night sky is mostly dark, this seems to suggest that the universe is not infinite. Several alternative explanations have been proposed, but the fact that Olbers’ paradox has not been decisively proven for 300 years is telling. Image credits: Kmarinas86 / Wikipedia.

The truth is, we don’t know if the universe is finite or infinite, and we may never know. The complexity of the problem seems, at least now, insurmountable. But here’s the good thing: it might not really matter.

Even if the universe isn’t infinite per se, there’s a good chance it is practically infinite. This means that some areas might lie so far away from us that we could never reach them. Since according to our current understanding of physics nothing can go faster than the speed of light, considering the accelerating expansion, some areas might simply be mathematically unreachable — we can never interact with them in any way.

The size of the Universe is difficult to define. Because we cannot observe space beyond the edge of the observable universe, we can’t know for sure if it is infinite or not. We have a good idea of how big our observable universe is, but that’s probably just a tiny piece in a much larger puzzle. How big that puzzle is remains an ongoing matter of research — and will likely remain so for years to come.

## 1 Answer 1

All statements like "when the universe was the size of a grapefruit" refer to the currently observable universe. As the universe has a finite age and light travels at a finite speed (and there is nothing infinite going on with expansion), the observable universe is a finite patch.

I discussed some of the different notions of horizons in answering another question. The "observable universe" is taken to extend out to the particle horizon. That is, it includes precisely the points in our current time slice whose past worldlines (assuming they simply go with the expansion of space and have no peculiar velocity with respect to our reference frame) intersect the interior of our past light cone.

If you think of galaxies as marking these points, these are precisely the galaxies that we can see assuming arbitrarily good telescopes, since the light reaching us today was emitted as the galaxy crossed our past light cone.

Galaxies that started out too far away from us in an infinite universe haven't been able to get their photons to us. And indeed expansion will prevent most of them from ever getting to us.

The scale factor $a$ when the universe was the size of a grapefruit is simply the radius of a grapefruit divided by the radius of the current observable universe (about $46 mathrm$), or something like $10^<-28>$ (corresponding to a redshift of about $z = 10^<28>$). The idea is that the galaxies (or rather their precursor quantum fluctuations) inside this grapefruit-sized volume are exactly the galaxies inside our observable universe today. In comoving coordinates the grapefruit is the same $46 mathrm$ in radius then as our observable universe is now.

## Breaking the infinite pigeon hole theory

You have probably heard of the pigeon hole theory?
If we have more than 1 universe we probably have an infinite number of them and if we do we have infinite numbers of exact universe copies (infinite me you)

An interesting math idea, and interesting to think that an infinite number of us all exist.
The only thing that seems to have instant communication properties in our universe is Gravity.
Reason we orbit the sun at it's true location and not it's C location and probably why spooky action works also.
If we take that as a fact and do have infinite universes they probably instant communicate with each other also.

If we start with the infinite as exact copies of every universe then the left/right/top/bottom of each are not exact gravity matches on the next universe.
Instant divergence no matter how you place them.
Even if we have an exact copy of our universe somewhere in the infinite it's unique location in infinity will assure it being unique.
Infinite randomness and just 1 of me and 1 of you.

#### Catastrophe

##### Approaching asteroid? Is this THE one?

"and if we do we have infinite numbers of exact universe copies (infinite me you)"

and then you must have enough alternate universes for each person (world population = . billion, and that is just Earth. And why not choices for rabbits and bacteria?) to have infinite choices.

#### Jim DeMaio

Well infinity is a big number Consider the universe size in the BB model, only 46.5 billion light years radius, How Big Is the Universe?, https://www.livescience.com/how-big-universe.html

Presently telescopes can only see out to about 13.5 billion light-years from Earth (z

12) so that leaves 33 billion more light-years presently not observable. Now this discussion introduces an infinite number of universes.

How do you plan to observe those infinite number of universes from Earth?

#### Catastrophe

##### Approaching asteroid? Is this THE one?

"How do you plan to observe those infinite number of universes from Earth?"

Who says that is possible?

#### Voidpotentialenergy

Well infinity is a big number Consider the universe size in the BB model, only 46.5 billion light years radius, How Big Is the Universe?, https://www.livescience.com/how-big-universe.html

Presently telescopes can only see out to about 13.5 billion light-years from Earth (z

12) so that leaves 33 billion more light-years presently not observable. Now this discussion introduces an infinite number of universes.

How do you plan to observe those infinite number of universes from Earth?

#### Voidpotentialenergy

"and if we do we have infinite numbers of exact universe copies (infinite me you)"

and then you must have enough alternate universes for each person (world population = . billion, and that is just Earth. And why not choices for rabbits and bacteria?) to have infinite choices.

I think as a math problem it's a great one for thought but in reality the location and interference of each in it's unique location will never allow a duplicate.

#### Voidpotentialenergy

Well interesting discussion here and some questions. I use this definition of science.
Here are five points that science must meet according to a 1982 Fed court and judge ruling. The essential characteristics of science are: 1. It is guided by natural law 2. It has to be explanatory by reference to natural law 3. It is testable against the empirical world 4. Its conclusions are tentative, i.e., are not necessarily the final word 5. It is falsifiable.

Galileo's observations of the Galilean moons moving around Jupiter in the early 1600s that shocked the geocentric astronomy, meets these standards. Consider Cat post #5 and others here.

#### KC Strom

Well infinity is a big number Consider the universe size in the BB model, only 46.5 billion light years radius, How Big Is the Universe?, https://www.livescience.com/how-big-universe.html

Presently telescopes can only see out to about 13.5 billion light-years from Earth (z

12) so that leaves 33 billion more light-years presently not observable. Now this discussion introduces an infinite number of universes.

How do you plan to observe those infinite number of universes from Earth?

Question for you. How is it known that present telescopes can only see to about 13.5 billion light years from earth?

#### Atlan0101

"Infinite numbers of exact copies." Not all that long ago I argued for it, that you could not have an infinite number of universes without an infinite number of exact copies included. Then, finally, I began to realize that exact copies crossed a line between exactly one entity [immortally] extant and those infinite numbers of exact copies. To put it another way, an infinite number of exact copies of any universe must exist as that infinity and yet, at exactly the same time, be exactly one and the same universe. Being the same they could never cross or meet, no particle of one could ever do anything that would ever qualify as difference. An infinite number of [you] as space travelers could never leave [your] infinite numbers of exact universe copies without [you] leaving all of them all at once (an exact mirroring effect) and arrive wherever you would arrive in an exact copy of universe at exactly the same time.

The immortality of an entity in space is then linked to an immortality of that entity in time. The infinity and immortality of possibilities and eventualities.

Then comes 'local' (relative) and 'non-local' (not relative). The division of the Universe (singular) into universes (plural). The local universe includes the relativity of the [known] universe which extends to no distance farther out than the arrival [to you] of a collapsed history, a collapsed horizon, or mural of universe. The collapse of cosmic Complexity and Chaos over time and space into a picture of order that has nothing -- may have nothing -- to do with what was, or what is, really there in the infinity of the 'non-local' (the not relative). To steal from another saying, how many universes are there on / in the head of a pin?

KC Strom, #10 post question. Good question BB cosmology uses Hubble constant and redshift to convert into distance, e.g., https://ned.ipac.caltech.edu/help/cosmology_calc.html

I generally use Calculator I or II, use defaults and change redshift (z) to whatever like 12.0. The CMBR redshift is about 1100, thus light-time or look back time distance about 13.8 billion light years. Redshift is how the BB model interprets distance using look back time or light time. The only direct distance measurement is stellar parallax and that is very limited in distances from Earth. In the cosmology calculators, the object's z number converts to light-time distance from Earth but because space continues to expand, the comoving radial distance for the object (where it is now), very much farther away and not observable using telescopes on Earth, presently.

#### KC Strom

KC Strom, #10 post question. Good question BB cosmology uses Hubble constant and redshift to convert into distance, e.g., https://ned.ipac.caltech.edu/help/cosmology_calc.html

Correct me if I am wrong, but I believe I have read that there may be issues with the Hubble constant? Correct? If so, any thoughts about implications of such problems with respect to the Distance calculators?

#### KC Strom

What's a couple of billion years among friends. So, given that variability, our current telescopes can see about 11.8 to 15. 8 billion light years away? True?

Can you give me a "quick and dirty" sense as to how sensitive these models are to redshift observations? I'm starting to understand there are two "types" of observable redshift. Expansion of space itself and the movement of a body within that space. Correct?

KC Strom, ref post #15. From what I know, the cosmological constant is *super sensitive* and wrong value here using General Relativity, space expands so fast nothing is here The Cosmological Constant Is Physics’ Most Embarrassing Problem, https://www.scientificamerican.com/article/the-cosmological-constant-is-physics-most-embarrassing-problem/

QM and vacuum energy density just makes things worse for expanding space, some say 10^120 or more magnitude error between assuming cc value allowing space expansion (but not too fast) and what happens with vacuum energy using QM (blows the universe out, we are not here). My chief concern is post #1. How can this be shown to be science, thus verifiable like Galileo observations at Jupiter? So far it seems, the infinite number of universes all around me are not observable thus fail to meet science standards in my opinion.

#### KC Strom

However, unless I'm mistaken, QM gives this idea a "non-zero" probability of being true.

#### Voidpotentialenergy

"Infinite numbers of exact copies." Not all that long ago I argued for it, that you could not have an infinite number of universes without an infinite number of exact copies included. Then, finally, I began to realize that exact copies crossed a line between exactly one entity [immortally] extant and those infinite numbers of exact copies. To put it another way, an infinite number of exact copies of any universe must exist as that infinity and yet, at exactly the same time, be exactly one and the same universe. Being the same they could never cross or meet, no particle of one could ever do anything that would ever qualify as difference. An infinite number of [you] as space travelers could never leave [your] infinite numbers of exact universe copies without [you] leaving all of them all at once (an exact mirroring effect) and arrive wherever you would arrive in an exact copy of universe at exactly the same time.

The immortality of an entity in space is then linked to an immortality of that entity in time. The infinity and immortality of possibilities and eventualities.

Then comes 'local' (relative) and 'non-local' (not relative). The division of the Universe (singular) into universes (plural). The local universe includes the relativity of the [known] universe which extends to no distance farther out than the arrival [to you] of a collapsed history, a collapsed horizon, or mural of universe. The collapse of cosmic Complexity and Chaos over time and space into a picture of order that has nothing -- may have nothing -- to do with what was, or what is, really there in the infinity of the 'non-local' (the not relative). To steal from another saying, how many universes are there on / in the head of a pin?

Tough to give any real proof if we are it the one and only universe and nothing else exists.
Or we are just 1 universe in a sea of infinite BB universes.
Or endless fluctuation is the universe and our BB is just 1 of an infinite number of them in it.
Dark flow/great attracter is pointing to something for sure and IMO is the answer or beginning of an answer

Time/location/interference tough to imagine an exact copy of anything in an endless bag of marbles that interact in a unique way with every marble in the bag in a different way.

## Does size become fictional in an infinite universe?

Currently, we don't know if we live in an infinite or finite universe. But let's say, for the sake of argument, that we do live in an infinite universe. So that if we would have a space ship with an infinite amount of fuel, we could keep on going forever. Infinity is something the human brain can't really comprehend, because from the start of our lives we experience everything to have a beginning and ending, even life. So to think there is something, or in this case everything, that just keeps on going for ever, is really mind bending.

But if our universe is indeed infinite, would this mean that size of any kind becomes purely fictional if we look at the bigger picture? If we look from our own perspective measuring things is no problem, since we are finite in length, width and depth, we can perfectly measure something from our perspective, and even a-dress a number to it. This number will give us an approximation of how big or small an object is.

What if we take a grain of sand on the beach? We could perfectly measure this compared to the size of the beach we found the grain in. But what if we keep on expanding this beach, the grain of sand would get relatively smaller and smaller. So now we take our universe that is in this case infinite, and we compare the Earth to it. The size of the Earth would we infinitely small, compared to an infinite universe. Because the bigger a space gets, the relatively smaller objects within it get.

Like if there where to be a person with an infinite amount of money, (not taking the economical catastrophe of this in to account), from his perspective everything would be free. Because when he would spent a certain amount of money, it wouldn’t be noticeable on his balance.

Does this mean an infinite universe would cancel out size of any sort? I think it does. If we could look from the universe’s perspective, the word 'size' wouldn't exist in our dictionary.