Two possiblities exist: either the Universe is finite and has a size, or it’s infinite and goes on forever. Both possibilities have mind-bending implications.
In another episode of Guide to Space, we talked: “how big is our Universe”. Then I said it all depends on whether the Universe is finite or infinite. I mumbled, did some hand waving, glossed over the mind-bending implications of both possibilities and moved on to whatever snarky sci-cult reference was next because I’m a bad host. I acted like nothing happened and immediately got off the elevator.
So, in the spirit of he who smelled it, dealt it. I’m back to shed my cone of shame and talk big universe. And if the Universe is finite, well, it’s finite. You could measure its size with a really long ruler. You could also follow up statements like that with all kinds of crass shenanigans. Sure, it might wrap back on itself in a mindbending shape, like a of monster donut or nerdecahedron, but if our Universe is infinite, all bets are off. It just goes on forever and ever and ever in all directions. And my brain has already begun to melt in anticipation of discussing the implications of an infinite Universe.
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Haven’t astronomers tried to figure this out? Of course they have, you fragile mortal meat man/woman! They’ve obsessed over it, and ordered up some of the most powerful sensitive space satellites ever built to answer this question.Astronomers have looked deep at the Cosmic Microwave Background Radiation, the afterglow of the Big Bang. So, how would you test this idea just by watching the sky?
Here’s how smart they are. They’ve searched for evidence that features on one side of the sky are connected to features on the other side of the sky, sort of like how the sides of a Risk map connect to each other, or there’s wraparound on the PacMan board. And so far, there’s no evidence they’re connected.
In our hu-man words, this means 13.8 billion light-years in all directions, the Universe doesn’t repeat. Light has been travelling towards us for 13.8 billion years this way, and 13.8 billion years that way, and 13.8 billion years that way; and that’s just when the light left those regions. The expansion of the Universe has carried them from 47.5 billion light years away. Based on this, our Universe is 93 billion light-years across. That’s an “at least” figure. It could be 100 billion light-years, or it could be a trillion light-years. We don’t know. Possibly, we can’t know. And it just might be infinite.
If the Universe is truly infinite, well then we get a very interesting outcome; something that I guarantee will break your brain for the entire day. After moments like this, I prefer to douse it in some XKCD, Oatmeal and maybe some candy crush.
Consider this. In a cubic meter (or yard) of space. Alright, in a box of space about yay big (show with hands), there’s a finite number of particles that can possibly exist in that region, and those particles can have a finite number of configurations considering their spin, charge, position, velocity and so on.
Tony Padilla from Numberphile has estimated that number to be 10 to the power of 10 to the power of 70. That’s a number so big that you can’t actually write it out with all the pencils in the Universe. Assuming of course, that other lifeforms haven’t discovered infinite pencil technology, or there’s a pocket dimension containing only pencils. Actually, it’s probably still not enough pencils.
There are only 10 ^ 80 particles in the observable Universe, so that’s much less than the possible configurations of matter in a cubic meter. If the Universe is truly infinite, if you travel outwards from Earth, eventually you will reach a place where there’s a duplicate cubic meter of space. The further you go, the more duplicates you’ll find.
Ooh, big deal, you think. One hydrogen pile looks the same as the next to me. Except, you hydromattecist, you’ll pass through places where the configuration of particles will begin to appear familiar, and if you proceed long enough you’ll find larger and larger identical regions of space, and eventually you’ll find an identical you. And finding a copy of yourself is just the start of the bananas crazy things you can do in an infinite Universe.
In fact, hopefully you’ll absorb the powers of an immortal version of you, because if you keep going you’ll find an infinite number of yous. You’ll eventually find entire duplicate observable universes with more yous also collecting other yous. And at least one of them is going to have a beard.
So, what’s out there? Possibly an infinite number of duplicate observable universes. We don’t even need multiverses to find them. These are duplicate universes inside of our own infinite universe. That’s what you can get when you can travel in one direction and never, ever stop.
Whether the Universe is finite or infinite is an important question, and either outcome is mindblenderingly fun. So far, astronomers have no idea what the answer is, but they’re working towards it and maybe someday they’ll be able to tell us.
So what do you think? Do we live in a finite or infinite universe? Tell us in the comments below.
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38 Replies to “Is the Universe Finite or Infinite?”
Good except you can spin out variations – bounded or unbounded for example. A spherical universe is bound but you can go around it forever (a 3d visible universe bent around in 4d space for example.)
My vote? Infinite. Definitely. And all of me agree.
Ok, try this one on for size.
The universe is finite, just like the number of souls in the universe.
If you think in terms of reincarnation, we are reborn and hopefully advance in our way to becoming saintly.
When you die, you can be reborn anywhere in the universe, doesn’t mean you will, but you can.
Souls are always moving depending on the population of the planets in the universe.
On top of that, there is a group of Gods, Jehovah is the one that oversees this part of the universe but the universe is divided into quadrants, there is a God for each with one overseeing all.
The reason there is newborn deaths is because no being can be born without a soul, and if it is, it dies.
This Universe is huge, lol a relative term, but it is not infinite, just like there are only so many souls.
I would be glad to discuss how I came to this conclusion if you would like.
My email address is [email protected]
When I was a schoolboy in the sixties, I wanted the universe to be bounded on the surface volume of of a 4D sphere, with time as the radius vector. That seemed neat as it gave you the Hubble shift, and made time the odd vector out, and didn’t waste any of the 4D time-space. It doesn’t fit with relativity or the evidence, though.
10^80 particles in the observable universe sound like the figure from Dirac’s LNH paper of 1937…
That’s another lovely idea, but it would need gravity to vary with time, which is pretty much doesn’t. However, I had a search for the number of particles in the observable universe, and I can only find this figure.
The universe is infinite, AND getting bigger. Galaxies “appear” to be moving further apart, but not because of a “big bang.”
Where does all the “stuff” come from? That question is answered not by looking up, but looking down. The book “Terra non firma Earth” reveals the geology, and “Big Breach Universe” on the android app store takes it to the next level from where the book leaves off.
If infinite yous bends your mind, the Big Breach will blow it up!
Infinite pencils. Love it.
I have conclude the the universe cannot disobey its own laws. the circular motion of visible matter cannot be denied, planets around a central sun, galaxies around a central black hole, multiple galaxies around a seemingly central “great attracter”. even electrons around a nucleus. why would the universe want to go on forever without definition when that is not the principle operation of its components ? Yes the universe is finite, disc like and comparatively flat. with leakage of matter from our universe into other multi-universes .
The universe is infinite. There are two sources of truth: science and religion. The other comments seem to be from scientists, which as an MD, I only pretend to be. Modern religion, which is as different from traditional religion as modern science is from the ‘science’ of 500 years ago, now sees ‘God’ as the infinite (obviously incomprehensible) power behind the infinite universe, represented here by periodic Educators who tell us of closer and closer approximations of true Reality.
My question is, as I observe all that I can, I see no perfect replication. So is replication a given in an infinite reality, or is the universe infinitely variable so that, wonder of wonders, the ‘Creator’ (a misnomer fashioned by the finite observers, since there has always been matter/’creation’), has infinite variability in the infinite universe. We think that ‘infinity’ presupposes replication, but that’s human math. Divine math perhaps does not rely on our computations.
The universe must be infinite. If we try to define finite bounds for the “universe”, the very definition of a bound means there is something outside of the boundary, otherwise there would be no boundary. This would also mean we would need to re-define the universe to include what is outside the boundary. Either way, bounded or boundless, the universe or redefined universe is infinite.
If we are going to discuss boundaries, give some thought to including “Universe boundary in Einstein 1931 same as Lemaître 1927” (the issue was brought up by @weasle, but my response was not published. See
Anyway you make a good point: “What is outside the boundary?”
If someone hands me a closed cardboard box, I can then define a “size” for the box, and also what I mean by an “inside” and an “outside”. But I must have the physical box first; the box is not “made of” an inside, an outside, and a size. It is made of cardboard. . . Modern astronomy has been concerned with the inside, outside, and size of the Universe, but has not defined “the box” itself. Additionally, the thinking now seems to be that the Universe is both centerless and edgeless. Maybe we have been asking the wrong questions.
This is related to the problem of defining space and time. Time is usually parametric in our equations (even in quantum mechanics), and so physicists are increasingly regarding it as non-fundamental (as Einstein did). The view gaining currency now is that “motion” is more fundamental and would make a better metric. In other words, let “c” (the speed of light) BE the “box” and let space and time be defined by that box. The space and time units are always changing (progressing) but the RATIO remains constant. The progression of space and time (“space/time” instead of “space-time”) would become the new Ether–the cardboard of the box, viz., something physical, though immaterial. It is dynamic (unlike the static Aether of old) but non-directional (“non-local”) and cannot be detected by a vector dependent experiment like that of Michelson-Morley.
Finding the right answers is hard enough. But because of what is NOT taught in our schools, we cannot even find the right questions!
It truly is a mind boggling question that makes you go bonkers, ..ahem..
I shared the following over a year ago:
“Finiteness” or “Infiniteness” of the universe is one of the many mysteries where scientists run around like a chicken with its head cut off trying to figure out!
Basic science posits that all “physical matter” is finite, the slightest motion in the universe (e.g. expansion, contraction, etc.) is “change,” and “change” means that the universe had a “beginning” since it is expanding, hence, it is temporal, hence, it is “finite.”
Now, the problem is science CANNOT figure out if the “spatial size” of the universe is “finite” or “infinite.” It is a logical conundrum. It has been one of the most complicated unsolved mysteries all along. Therefore, it became sort of a common practice to refer to the “observable universe,” that is made of “physical matter,” when speaking of the universe, and that it is “finite.”
If you research this topic, you will find a vast amount of different opinions, and they pretty much revolve around this question: How can the universe have a limit in “spatial size,” and what is beyond that limit?!
Many people think that it does not make sense for the universe to have a limit in “spatial size,” some think it is flat, some think it is spherical, and so on and so forth, but no one knows for sure.
I myself is of the opinion that the universe is “finite” in material (which is already established by science as aforementioned) and in “spatial size,” since I believe the “Origin” of it is outside its “beginning,” and that “Origin” is “holding it in suspension.” I believe that “Origin” is “Metaphysical” (non-physical) and non-temporal (without beginning nor end,) that is Eternal.
I believe that “Origin,” aka “First Cause,” is God Almighty, the Father, Son (Lord Jesus Christ) and Holy Spirit.
Here is a recent historical perspective of the complexity of the subject matter:
I was just thinking recently that since the universe is expanding, doesn’t that mean new “space” is being “created” all the time?!
Yaaaaaaaaaaayyyy!!!! 😀 😀 My thoughts exactly. 🙂
I believe that the “Universe” as we know it or is defined by us as the extent of our Bounded Big Bang, is finite, whereas the Cosmos is the immense Darkness that is Space. That in my own opinion is infinite.
Seeing that we can’t even get past the moon right now I don’t think it matters!
Sometimes I think we stretch out our minds to contemplate that which is beyond our comprehension or ability to prove, because we don’t want to dwell on our limitations.
I hope the universe is infinite otherwise humans would be limited in possibilities. However, if ,as scientists tell us, we see evidence of the big bang and inflation every direction we look, then this would be the wrap-around. We can’t see beyond that because we can’t see past where nothing exist. The wrap-around does exist.
if the universe is relativistic as the special theory of relativity says and experiments to date have shown it to be, then one can prove that the universe is Euclidean, finite and unbounded. thanks.
Confused by that last, “finite and unbounded”. How can something be unbounded if it is finite. Doesn’t that prove to be a contradiction?
I think that whether we consider the “Universe” infinite or finite is dependent on what we define as the Universe. If our Universe consists of our Known stars or that which we can see, or what seems to be part of our Big Bang, then it is finite. On the other hand the Cosmos, which I prefer to think of as the dark of space is probably infinite. In which case could or have other “Universes” existed or exist now. We will probably never know. If the final Black Hole that wins out over all the rest is as powerful as I suspect it will be. Then I will assume that not one bit of matter that was thrown out by the Big Bang will escape it. I highly doubt that we could or will ever discover the means to get far enough away from it to avoid being swallowed up. To my mind it is inescapable and inevitable. But out there in the far reaches of infinite space, I suspect that other “Universes” do exist. Space couldn’t be that infinite and yet remain that empty.
I believe it is finite from the standpoint of energy-mass. But it is also centerless and edgeless. The question of “How big is it?” is like asking “How big is time?”
The Universe has what physicists call “local” and “non-local” behaviors. The local behaviors are composed of space/time relations and the non-local behaviors are based on the inverse: time/space relations. The local one is what we see when we look at the stars at night. The non-local one is not localized in space and so would appear as a uniform homogeneous background of radiation and particles. The “background radiation” would include the whole spectrum, not just the microwave background, but also the X-ray background, which is surprisingly bright and uniform. There would also be particles with “inverse masses” moving through our reference system at (approximately) the speed of light, and also homogeneous and isotropic. Cosmic rays fit this description. Both behaviors are statistically the same as seen from within their own reference systems. From our standpoint they are observationally superimposed.
At the speed of light space/time and time/space become equivalent (1/1 is equal to its inverse, 1/1). It would be interesting, to say the least, to see what the Universe looks like from THAT perspective.
None of this is taught in the schools. It will not appear in mainstream journals either: if an article were submitted, it would be thrown out by the editors; it would never even see peer review, where it would probably be thrown out as well. Because of this, we are missing a lot of rich and fascinating insights, as well as astonishing practical applications.
Why 8 billion years ago the speed of the expansion of the Universe was less than it is now? According to the laws of attraction the speed of the expansion of the Universe was supposed to be less now than 8 billion years ago… but the speed of expansion is accelerating as if our “Dwarf Universe” is attracted and cannibalized by other Giant Universes … I’d say from the Local Group of Universes from vicinity in the Multiverse!
The fact that at “the Edge of the Universe” were found many “adult” galaxies, well formed, instead of young undeveloped galaxies as they were supposed to be in the Early Universe, makes me believe that those galaxies are adult “alien” galaxies from other Universes from vicinity much older than our Universe (that’s why we see those galaxies very well formed), and that is a proof that our Universe is merging with those Giant Universes from vicinity, like Milky Way will merge with Andromeda galaxy in the far future!
I’d say that the Universe is Finite and the Multiverse is Infinite. I’d say that there are Infinite Dimensions (One Super Dimension of Space) and the Multiverse is a projection of a Hyper-dimension onto a Sub-dimensional space (like a 3D object projects a 2 dimensional shadow and it is easer to get the idea if you understand that a hypercube is for a cube what a cube is for a square). Even the scientists can’t explain the existence of our Universe without adding more dimensions into equations… as if the creation (and evolution) of the Multiverse is a Top-Down process, not a Down-Up as if it would appear Out Of Nothing (that would be magic like in those stories with Wizards)! If the seeds of the Galaxies were created prior to the Big Bang(s) in the Hyperspace then the seeds of our Civilization were created there too…. so Mankind just follow the path of the “evolution” like an embryo in the womb, that can’t be detected by the ultrasound in the first seven weeks though it is there, follow the path to become an awesome human! http://www.facebook.com/octavian.peagu
Simply thinking – if its finite then it has to have a boundary, what is beyond that boundary then. Something has to start where something ends, right? So can not be finite. If we think in terms of three dimensions of distances then it has to be finite but time is not finite and can’t say how but space comes with this 4th dimension. I wish I could study more for a deeper insight but that depth seems to be infinite as well 🙂
Time itself can be finite. It can last for an incredibly long time, no pun intended. But when the Universe is all stretched out and energy is all spent and absolute zero is reached across the entire Universe, the very last thing that will leave this Universe is time.
If the Big Bang theory (with inflation, of course) is correct and all the matter/energy, both visible and dark, came into being some 13 billion years ago, then it hardly seems that this component could be infinite in size. Perhaps the question should be “Is the space/time matrix, within which all matter/energy exists, infinite or finite?” or “What is the topology of space/time?”. While we can mathematically manipulate values for space and time, we really do not understand dimensions at a physical level, so it’s probably an unanswerable question at this stage.
Finite. Definitely Finite.
Infinity does not exist, it is a word (much abused sadly) that we use to “describe” the indescribable, “define” the indefinable, and even to “Eff” the ineffable.
Consider your example above, “if you travel outwards from Earth, eventually you will reach a place where there’s a duplicate …”, the distance travelled is measurable (albeit mind numbingly vast) and therefore finite, the “duplicate of you”, can’t be an exact duplicate, because if it were, it wouldn’t be where you found it, it would already be at a distance from where you are then, equal to the distance of there to where you started from, equally failing to find it’s “first” (your second) duplicate for the same reason. [ouch my head already :-)]
However, accepting that the duplicate would be there at a finite distance, the total distance between you and the nth duplicate is also clearly finite (although I’ll cede that “n” being undefined, the distance could be considered “nthfinite”)
Also, as has been mentioned in earlier posts, there is a “start” point, so bounded at t=0 therefore finite. Although as someone who accepts bang/crunch feedback “cycles” I hasten to add that for me, t=0 is not the most recent big bang event. (I suspect we are in a region(causal patch) of the 9th iteration.)
[The feedback “problem” of LQG is resolved if you allow a Fibonacci Tree expansion of the level of dimensionality at each crunch/bang event, starting from a single quantum event.]
So, BIG, yes, but definitely finite.
Nobody expects to travel so far you hit a wall. So the question is “is our physical universe of matter and energy finite with empty space going on forever around it?” Or does our universe contain an infinite amount of matter? Doesn’t seem likely. I think all that makes our universe must be limited and if you could go far enough there is probably another universe and many others out there in their own stage of development. But how would we ever know?
The universe doesn’t repeat, but it doesn’t stay the same either. It is impossible for us to look around the universe and see replication, because as you look out you are also looking back in time relative to the speed of light. To make a simplistic analogy, according to the Big Bang theory we are like ants looking out across the surface of a deflating balloon: the further we look the more deflated it becomes. What you can expect to happen is that things become closer and closer together, which is exactly what we do see, with galaxies converging about 14 to 15 billion years. Also, the makeup of stars in the early universe consists more and more of hydrogen which would also follow from a finite universe. … The conclusion? Don’t get rid of your mirror, because it will be the only way that you will see the back of your head.
We have to accept the definition of what the universe is. Is it inclusive of matter as we know it? Then it is finite. Gravity would dictate that since the laws would apply at the local and distant points. So as I had said before, the universe cannot have a different laws at the local scale, different from that on the large scale. We would see the constant distortions of matter if the laws were different. As a result the overall gravitational force would cause matter to confine to a finite distribution. Beyond our universe, these might be nothingness and other universes obeyi g their own laws.
I agree with the assertion that infinity does not exist within our universe. To have infinity, we and everything else would have to have crossed a past infinity to get to this point. Seems infinity can’t be crossed. Infinity is endless; you’d never get there. In other words never get to “here”, as it were.
I doubt randomness exists without infinity, because the yardstick of infinity would be needed to measure it against. I like when Fraser posts these kinds of posts. Nice to see so many opinions posted as a result. I’m suggesting Fraser does another post, in which he asks whether randomness exist or not. The closest thing to randomness that I observe are the actions of living organisms.
Infinity may exist in a greater reality that has given rise to our universe. Infinity would probably require redefinition because I suspect that our universe (and thus spacetime also) originates from a greater reality deep in the quanta or beyond. I suspect spacetime is not a component of this greater reality. Can one have infinity without spacetime?
Your argument is similar to Zeno’s Dychotomy Paradox. Zeno argued that movement is impossible. His argument goes like this. To move a distance you first have to move 1/2 that distance. To move 1/2 the distance you have to move 1/4 the distance. To move 1/4 the distance you have to move 1/8 the distance and so on. Therefore, you have to pass an infinite number of points to reach your destination, so you never reach it. This is, of course, a fallacy.
You assume that we must have travelled an infinite distance to conclude that we must have travelled an infinite distance. This is circular reasoning, and also a fallacy.
I’m referring to crossing, or perhaps I should have better said passing through, an infinity of time. It seems any point in infinite time would have infinity behind it, and ahead of it. I was not referring to taking a bus with Zeno for a distance.
The actual math involved in this question is infinitely over my head, but I can often visualize the gist of the problem and even sometimes follow the physics. While I am a Christian, for my part I’d rather leave religion out of this question.. which might be a BIG mistake but that’s to be determined later. One thing that vexes my finite mind is trying to imagine exactly what is meant by the “observable universe” versus the “visible universe”. Wikipedia has a fair explanation (google “observable universe”) but then wanders about in a variety of wild theories. I hate all the confusion. (Am I at the center of THE universe or only at the center of MY universe?) As far as finite versus infinite, the answer to that may be unknowable.. but if the Big Bang happened once, who’s to say it can’t happen again? Big Bang II? Please, NIMBY!
One crazy theory about duplicate of yourself. The universe is finite, but space is infinite. Even it’s finite only portion of it we can see. The other portion is traveling away from us so fast we will never ever in human existent can see it. It means the universe will expand forever and galaxies will collide into each others and create new energy and galaxies. It will go on forever even after God decided the human race is to end.
Stop asking this stupid question! A 6-year old knows that the Universe and Infinity is beyond human comprehension.
I’ve entangled myself with this question all my life. In fact it has been the driving force for keeping up on the latest findings in cosmology and theoretical physics.
What I’ve learned so far is that with every advance we can only marvel at how much we have yet to learn.
But there is one area of theory that I’ve come to rely on that may be the most promising yet and that pursuit is within the confines of our own brain matter. Infinite is but an excuse for the unknown. As we grow in using more of our intellect, we will find more to understand.
The Universe is definitely finite but WITHIN an infinite Consciousness. Our Universe is merely the Energy of a brief Dream [13.5 billion years is a brief time comparing to Eternity] inside the Infinite “I AM”.
“I AM” is defined as the Ultimate Wisdom and Power or simply as HaShem. Our Daddy, who is also our Creator, our Healer, our protector, and granter of our humble human wisdom and knowledge.
Our Universe occupies only a small area of The Great Mind of HaShem. For IN HIM we live, and move, and have our being. We may call it The Area of the Dream. It is NOT our Dream! We are INSIDE an Infinite Mind who is also The Creator of Space and Time as we experience it every day.
The Universe someday will cease to exist, the Holy Dream will end.
We, however will never cease to exist because we will transcend to the Infinite Dimension of the Eternal Memory of the Great Mind of HaShem. So, these are very good news . Just love Hashem with all your heart and your neighbor as thy self.
Love you guys.
Your argument is quite wrong, the assumptions are not enough to justify such a strong conclusion (“eventually you will reach a place where there’s a duplicate cubic meter of space”). To begin with, you need the additional hypothesis that *all* matter in such infinite universe is made from a *finite* set of elementary particles. If you think about it, this is a very strong assumption once you accept the possibility of an infinite number of particles. Why rule out the possibility of infinitely many different types of elementary particles? In that case a given cubic meter of space may indeed be unique because once you go far enough you stop finding similar particles so you “miss your chance” of finding a duplicate.
But even if you assume the same finite number of elementary particles throughout the entire (infinite) universe, the argument still fails, because there’s no law that requires a given configuration to repeat itself. You are probably using the following probabilistic argument: If all configurations are equally likely then the probability of a given configuration never repeating itself is zero. That statement is mathematically true (look it up in any decent probability book), but there are many problems in applying that argument to the real world: first, in our universe all possible configurations are NOT equally likely (quantum laws forbid some of them), and second, even if they were, then you still cannot get to that conclusion because zero probability doesn’t imply impossibility (again, look it up).
(multiverse aside) According to theoretical physicist Janna Levin, if our universe is infinite, then possibilities are infinite – infinite galaxies, infinite number of planets, and given infinite time to search, I would eventually find another guy, on another planet, wearing gray sweats, typing on a keyboard, explaining why he thinks the universe is not infinite.
I hate to make a guess based on : “(A) is the right choice because (B) is too silly” …but in this case, B is too friken silly.
You all seem to be forgetting one principle, the God principle.
God created the universe but it isn’t infinite.
Everything has a beginning and an end, it may be so distant we can’t fathom it, but it still exists.
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