How Deep Does the Multiverse Go? 202
StartsWithABang writes Our observable Universe is a pretty impressive entity: extending 46 billion light-years in all directions, filled with hundreds of billions of galaxies and having been around for nearly 14 billion years since the Big Bang. But what lies beyond it? Sure, there's probably more Universe just like ours that's unobservable, but what about the multiverse? Finally, a treatment that delineates the difference between the ideas that are thrown around and explains what's accepted as valid, what's treated as speculative, and what's completely unrelated to anything that could conceivably ever be observed from within our Universe.
It's turtles all the way down (Score:5, Interesting)
It's turtles all the way down.
Re:It's turtles all the way down (Score:5, Insightful)
But, is it turtles all the way up?
Re: (Score:3)
MIND. BLOWN.
Re:It's turtles all the way down (Score:4, Funny)
It's turtles everywhere!
That extra mass everyone is talking about? Dark Turtles.
Re: (Score:2)
No, they're just hiding. Like ninjas.
Many worlds (Score:5, Funny)
In one version of reality, this is a first post!
Re: (Score:2)
That depends on your concept of identity across worlds. Surely the first post in another multiverse cannot be entirely identical to one in this one, as it exists in a different multiverse, not this one. Furthermore, it also differs from "this" post in that it is first in reply to the article posted on Slashdot*, or /.*. It also differs in that it wasn't made by you, but you*, who further differs from you in such a way that allows him to make that first post where you failed. If you're already so different f
Re: (Score:2)
Except in the one where you posted saying it wasn't, but were mistaken because it actually was. That might not be too far from the one where I'm GWB, a frequent Slashdot poster. It's interesting to ponder the concept of what "infinity" really means when you consider all the possibilities on some mundane thing like that.
Re: (Score:2)
If he were the first poster, he wouldn't have had the thought to point out that he wasn't the first poster. Hence, if he still posted a comment, it wouldn't have had the same content and thus could not be considered to be *that* comment above.
Unless if he hallucinated that there was already a comment somehow when there wasn't, I suppose.
Re: (Score:3)
What is your criterion for restricting the variations? Why are "Anonymous Coward" and "Anonymous Poster" possible, but not "XFFSF Poster" and GWB as an active Slashdot user?
Re:Many worlds (Score:5, Insightful)
You've missed the point.
Try a different example. Consider that there are an infinite number of values between 0 and 1. While infinite, none of those values will be 2.
If that's not to your liking, consider something like Penrose tiling where a pattern formed from just two shapes can tile infinitely without repeating.
See, when you ask:
What is your criterion for restricting the variations?
There need not be any such criterion. See, just because a thing is possible does not mean it will necessarily be actualized even given an infinite number of universes.
Re: (Score:2)
OK, you've done a good job now of explaining what you mean; but my possibility is just as valid as yours. Maybe the multiverse has to include numbers beyond 1.0, and maybe it doesn't.
Maybe it's an infinite set full of bizarre possibilities, and maybe it's an infinite set full of subtle variations on our known theme. We just. Don't. Know.
Re: (Score:2)
but my possibility is just as valid as yours.
You've still missed the point.
Re: (Score:2)
You've still missed the point.
No I haven't. If we were discussing the set of prime numbers and I said "how about six" you could say, "No, because it's divisible by 2 and 3". The set of prime numbers is an infinite set with well known restrictions.
We're discussing alternative universes. If I say, "How about the one where I'm GWB?" You have nothing to say because this discussion started with the premise, and ONLY the premise that alternative universes are an infinite set. There were no other criteria s
Re: (Score:2)
The point was that in infinity does not necessitate every possibility. There is no compelling reason to believe otherwise.
I submit that in the absence of such criteria not only may we speculate on all possibilities, we must.
Again, we have absolutely no reason to suspect that every potentiality is actualized. We do, however, have reason to suspect that it's not.
The AC said:
Seems you misunderstand infinity. It does not mean that everything (or anything) which is possible is somewhere actual or true.
Which should be obvious to you by now. It's trivial, after all, to describe an infinity of universes without assuming every potentiality is actualized. (On an interesting note, it is also possible to describe a plurality of universes i
Re: (Score:2)
Let's cycle back to what I said in the first place:
That might not be too far from the one where I'm GWBM
Do you see the word might in there?
You and a lot of other people incorrectly read that as must, hence you are arguing against something I never said, namely that infinity necessitates all possibilities. I got caught up in it a bit myself, going off on how unconstrained infinity may include all possibilities until proven otherwise, which I maintain is true.
Fact is, this whole thread actually seems to b
Re: (Score:2)
See, just because a thing is possible does not mean it will necessarily be actualized even given an infinite number of universes.
Isn't it a mathematical axiom that any event with a >0 probability of occurring, given infinite trials, has a likelihood 1 of occurring?
Re: (Score:2)
Nope
Ever so helpful (Score:2)
[citation needed]
Discrete probability distribution [wikipedia.org] is the best link I can find at the moment for something that has been in the first lesson of the section on probability in every math textbook I've ever seen.
But this is an article about quantum physics so I suppose I should just assume that everything we "know" about math is a lie and just get over it, huh.
Re: (Score:2)
Don't feed the troll. If the best counterargument to a logically stated position is simply "no", then there's no point in discussing this further.
Re: (Score:2)
Consider that there are an infinite number of values between 0 and 1. While infinite, none of those values will be 2.
just because a thing is possible does not mean it will necessarily be actualized even given an infinite number of universes.
One statement does not follow the other. 2 cannot exist between 0 and 1. It is impossible. So your example is not relevant to the point you're trying to make.
If something is possible, it is probable. Given an infinite number of universes, the probable is reality in at least one (but likely more than one) of them. You cannot put limits on infinity.
You're trying to say that just because something is possible and therefore probable does not mean it'll happen. That's only true under the assumption of a finite d
Re: (Score:2)
No, it's not.
Re: (Score:2)
See my post just prior to this one. It all hinges on the word "might" in my first post. I believe you improperly inferred that I was stating all alternatives *must* exist, as opposed to *might* exist. Yuck, I don't relish the thought of being in Nietsche's company. However, that's based on experiences with my peers when we were teenagers. They were just exasperating to talk to, and one of them actually went certifiably insane.
Re: (Score:2)
There are an infinite worlds, yet in none of those you're GWB
At least that explains why in this universe GWB doesn't punch himself in the face every now and then.
Math? (Score:5, Insightful)
The observable universe is observable because there has been time for the light to travel that far, which can not exceed the age of the universe. Therefor, if the universe is 14 billion years old, then the furthest we could see in any direction is only 14 billion light years, giving a maximum, diameter of 28 billion light years.
So why does the summary say it's 46 billion L.Y. across and only 14 billion Y. old?
Re:Math? (Score:4, Insightful)
If you assume a static, never-changing, fixed space... you might have been right.
Isn't this how we know it's expanding?
Re: (Score:3)
Special relativity
http://en.wikipedia.org/wiki/S... [wikipedia.org]
Re: (Score:2)
Re:Math? (Score:5, Informative)
Given a sufficiently large distance between two discrete points in the universe, the rate of hubble expansion between those points can exceed C.
http://www.universetoday.com/1... [universetoday.com]
You can think of it this way:
You have a ruler-- You can only move along the ruler at at most, 100 units per second. (we will use this as an analogue for going C) However, for every second, for every 1000 units distance on the ruler, a new unit of distance magically appears. If you have a distance between 2 points that is sufficiently large, (In this case, in excess of 1,000,000 units) more than 100 units will be introduced every second, which is faster than your maximum rate of traversal-- So you will NEVER reach the target-- it receedes faster than you can get to it.
http://www.universetoday.com/1... [universetoday.com]
In regular terms for Slashdotters (Score:2)
It is just like when you start chasing a girl but never catch her because she keeps running away.
Just be careful, sometimes but only very rarely, do they suddenly turn around and catch you. That is how I ended up married.
Re: (Score:2)
No.
Re:Math? (Score:5, Informative)
Because the expansion of space is independent of the light traveling through it, and the light that has just arrived came to us in some cased from objects that are now much further away than 14B lightyears
Re: (Score:2)
That would be cases, not cased. My Apologies
not true, IIRC (Score:2)
nonsense statement...had to read twice to be sure, but this is just technobabble and not based on scientific definitions of "space" and "light"
if I understand you correctly, you're wrong...the whole point of GP, one which I think you're attempting to address, is that the only reason we know the universe's s
Re:not true, IIRC (Score:4, Informative)
nonsense statement...had to read twice to be sure, but this is just technobabble and not based on scientific definitions of "space" and "light"
That's weird, I understood it perfectly as an (admittedly somewhat simplified) explanation of how space expands and how light travels through that expanding space. Don't blame your lack of understanding on what you imagine to be the GP's lack of clarity.
in other words, **NO** there is not 'light' hitting us from 14B ly+
No-one said there is. There is light hitting us which was emitted by objects which are now* more than 14 billion light years away.
*for a given value of "now," that is, but I'm not sure I'd enjoy trying to explain that to you.
you can't explain b/c you don't know (Score:2)
it's not that you don't *want* to explain, or that you think i wont' understand...no...
you can't explain it
you actually don't understand it yourself and are BS'ing
i did make a coherent point, referencing the two main things we have that give us the age of the universe now
> Cosmic Microwave Background
> Gamma Ray Bursts
There are others, but any new distant event is usually first compared to the two things listed above
Re: (Score:2)
what is your point?
you're saying that those galaxies/quasars were formed before the CMB?
you know enough to be dangerous...that's all...have fun with your redshift calculator...there's no productive discussion to be had here
ok now i get it (Score:2)
yes...you all were right and I was wrong...
see, this is my fault for being so angry about the 'multiverse' theory...it's a ridiculous tautology...
but yeah...it get what you guys were trying to say about expansion of space vs light age...
yeah...sorry
Re: (Score:3)
Let me put it in terms you can understand: If you hold a rubber band with one end in each hand, and put an ant on the rubber band at one end headed toward the other, and the ant moves at a constant rate toward your other hand, and as the ant moves you stretch the rubber band, then your hands will be further apart than the ant has moved when the ant reaches your other hand.
If you have a favorite animal, I can rephrase to accommodate.
Re: (Score:3)
If you have a favorite animal, I can rephrase to accommodate.
Probably wouldn't work with my dog, it would just eat the rubber band.
inaccurate analogy (Score:2)
your analogy, which i read elsewhere on this thread, is incorrect
**we don't know** the nature of 'space' and the 'universe' like you're making out
'space' is not like a rubberband and 'light' is not analogous to an ant crawling on said rubber band...it's just a bad analogy that doesn't prove anything either way
just confuses things
if i was so egregiously wrong... (Score:2)
you could have explained it more simply
your response is crap...you're being a condescention troll...telling me i need to read up on 'X, Y, or Z thing'
if my response was so dumb, you'd be able to correct things with a paragraph, maybe a bit more
if it's too complex to correct, then it's not something everyone with a college degree (or w/e condescending thing you made it out to be) would know
so explain in detail or STFU
typed a paragraph & made links (Score:2)
but still didnt engage in the actual discussion...regarding your links...***i already knew that***...or the basics of that...your second link...yes...it's "just a theory" that is unproven...based on several assumptions...but fine
**GIVEN ALL THAT**
you still haven't counted my point, which was that however we age the universe, it is based on certain criteria...therefore, my point still stands...this whole thread is pointless bullshit posturing
it's pointless to argue about the age of the universe...better to t
disregard last response (Score:3)
posting this here too...
yes...you all were right and I was wrong...
see, this is my fault for being so angry about the 'multiverse' theory...it's a ridiculous tautology (which we can argue about another time)
but yeah...it get what you guys were trying to say about expansion of space vs light age...
yeah...sorry
Re: (Score:2)
thanks for being cool...sorry i was a dick...
really i do know better but sometimes I just dont
Re: (Score:2)
The universe is expanding like others said... but it's still an incorrect statement. All of our measurements so far suggest that the universe is flat, and extends in all directions infinitely. It has no size, it's unending. Even more mind boggling is that if the many worlds theory is true, then there are also an infinite number of other universe that are equally as vast. Long story short? There really are Ewoks somewhere.
Re: (Score:2)
The universe is expanding like others said... but it's still an incorrect statement.
The statement did say "observable universe."
Grammar (Score:2)
"universe" = everything observable.
But that grammatical rule breaks down if you put the word at the start of a sentence.
Re: (Score:2)
Fan of Bucky, eh?
Re: (Score:2)
The observable universe is observable because there has been time for the light to travel that far, which can not exceed the age of the universe. Therefor, if the universe is 14 billion years old, then the furthest we could see in any direction is only 14 billion light years, giving a maximum, diameter of 28 billion light years.
So why does the summary say it's 46 billion L.Y. across and only 14 billion Y. old?
The universe is expanding all while light is in transit to our bug-eyed telescopes.
For details: http://arxiv.org/pdf/astro-ph/... [arxiv.org]
Re: (Score:3)
Re: (Score:2)
Re: (Score:2)
I've never heard the explanation as to why that makes light seem to go faster rather than seem to go slower.
Re:Math? (Score:4, Informative)
Most people can understand this on their own, but since you need some hand holding:
Imagine an ant on a rubber band. Mark the start position with a dot, let the ant walk for 5 seconds, mark the end position with a dot. The distance between the two dots will be greater if the rubber band was stretching while the ant was walking on it.
Re: (Score:2)
Why does the rubber band carry the ant forward? Isn't it equally plausible that the rubber band moves underneath the ant's feet while her speed remains constant, decreasing her speed relative to the rubber band?
Re: (Score:3)
Suddenly? She was born that way, with the W chromosome and all.
Re: (Score:2)
Because almost all ants are female.
Re: (Score:3)
That's called the luminiferous aether hypothesis.
Re:Math? (Score:4, Funny)
A better analogy would also represent the space time continuum and the gravity well relative to the ant.
See if your ant is walking on a large rubber sheet, then you drop a bowling ball on the spot the ant is currently at... oh wait, the universe just made my ant 2 dimensional.
But you will notice that it is travelling much slower now...
Re: (Score:2)
You're restating the question, not answering it.
Re: (Score:2)
Too bad (Score:2)
I was getting used to the notions of multiverse so broad there exists a copy of me somewhere with a penis in place of the nose and a nose in place of the penis. And that's far from the weirdest things out there.
Re: (Score:2)
I almost got to that universe once. But what was actually different was that I was a chicken.
Brian Green;'s multiverse book (Score:3)
Imagine an infinite number of exct copies of yourself, each sparated by immense distances. Image even more variants of yourslef, living slightly to greatly different lives.
Re: (Score:2)
Or maybe this life is as good as it gets for you and your multiverse you's.
Please explain (Score:2)
Consider the time axis, from minus infinity to plus infinity.
Somewhere along this axis the universe comes into existence.
Call this point t0.
Now why is t0 exactly t0? Shouldn't there be another universe, exactly equal to this one, with time t1 (!= t0).
Now even if time is created as part of a "big bang", there should be a "meta-time" for which this holds.
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Consider the time axis, from minus infinity to plus infinity.
Somewhere along this axis the universe comes into existence.
Call this point t0.
Now why is t0 exactly t0? Shouldn't there be another universe, exactly equal to this one, with time t1 (!= t0).
Now even if time is created as part of a "big bang", there should be a "meta-time" for which this holds.
No. Time is a part of this universe. There is no "meta" time, other universes do not necessarily have time. There is no t Minus infinity. We know exactly when time started (ok, to within a few trillionths of a second) You can no more go back further in time than that, than you can make a square circle.
It's something that's hard to talk about because our language is so wrapped up in the idea that time is endless, but it's not.
Re:Please explain (Score:5, Insightful)
FTA: "The most amazing thing about it, though, is that this is exactly what the Universe was doing before the Big Bang, only with a much greater energy and at a much faster rate! This was the period known as Cosmic Inflation."
Words like "before" presuppose the existence of time. If, as you postulate, time exists only as a function if this universe, then you have just established the de facto existence of "meta time" (at least if you believe TFA).
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Know how I can tell you didn't read TFA? Because he says exactly that - That inflation happened before the Big Bang, faster in fact than it did after
If it helps, you could consider the Big Bang the end of FTL inflation, though not 100% accurate (that "first 10^-32 seconds" thing assumes it lasted for a whole 10^-32 seconds, rather than starting at
Good article (Score:2)
Especially liked raised BS flag on many worlds interpretation crackpottery.
Here's the deal... (Score:2)
Re: (Score:2)
Stating that something must lay beyond the "edge" of the universe, as the submitter does, basically means the person doesn't really understand basic cosmology.
How deep? (Score:2)
Speculative. (Score:5, Insightful)
Anything dealing with multiverse is speculative. Math does not constitute evidence.
Re: (Score:3)
Re: (Score:2)
Anything dealing with multiverse is speculative. Math does not constitute evidence.
By that argument, everything we know about stars, quasars, black holes, and virtually everything else that isn't on our planet and relatively close to the surface is all speculative, too. Nearly everything we know about the stuff not immediately at hand is based on mathematical models, calibrated against "observations" which are often very, very indirect and themselves dependent on many layers of mathematical models derived the same way.
I don't know enough about QM and many worlds theories to know how muc
Re: (Score:2)
Nope. We can apply our mathematics to things within our universe because as far as we have observed, the laws of physics are constant throughout it. Outside of our universe, we have no idea what is going on, therefore our mathematics may likely be completely wrong and worthless.
The many-worlds hypothesis usually used in explaining the oddities in QM doesn't assume different physics.
Re: (Score:2)
But it allows them.
our mathematics may likely be completely wrong and worthless.
Re: (Score:2)
But it allows them.
our mathematics may likely be completely wrong and worthless.
Maybe. But this is an area in which we actually can make observations that allow us to refine the math, because it does make testable predictions.
Re: (Score:2)
Okay. Reading your comment, I just took issue with "assume" as it sounded like you were saying "it isn't required therefore it can't possibly ever happen."
Although I'm not quite sure how you mean we can "observe" the multiverse I wouldn't be surprised if there was some argument for that.
Re: (Score:2)
We probably can't observe the multiverse. What we can do is postulate how events might play out if, as is suspected, subatomic particles have some interaction with their counterparts in "nearby" universes. We can model the various possible explanations and use the models to generate testable predictions. Assuming that process ultimately rules out some of the models and favors others, we still won't know that there really are multiple universes, all we'll know is that a model that assumes there are, and assu
This is just one person's (Score:5, Informative)
What is the basis for the infinite universe? (Score:2)
Sure, there's probably more Universe just like ours that's unobservable,
This has come up before, and I ended up in an extended conversation with someone who was absolutely insistent that the universe was infinite. But he wasn't able to actually explain this. I don't see the basis for this assumption and I can't understand why it seems to be so widespread, is this some new(ish) theory that I haven't heard of? It's my understanding that the universe, as we currently know it (in other words the area effected by the big bang), extends only a few hundred thousand light years beyond
Re: (Score:2)
Cross Eyed In Agony (Score:2)
Re:I don't understand... (Score:5, Interesting)
The speed of light through space is distinct from the rate at which the universe itself expands. Weird fun things ensue. :p
Re: (Score:2)
Re:Wait a minute... (Score:5, Informative)
For fuck's sake. How many times must similar questions be asked?
http://science.slashdot.org/co... [slashdot.org]
These are all basically the same question, which reduces to "I'm going to assume that the people who spend their lives working on this can't do elementary arithmetic". Instead, they're working within the strongest theoretical framework they can encounter. In this case, that framework is general relativity and, specifically, Friedman-Lemaitre-Robertson-Walker spacetimes. A subset of the FLRW spacetimes are the de Sitter and anti-de Sitter spaces. These have exponential expansion or exponential collapse, and as one might imagine, this means that if you somehow attached little radar transceivers to fixed points in (anti-)de Sitter space then the distance between them will change far greater than the speed of light would imply. There is no contradiction here, because in general relativity, the "speed of light" means something propagating along null geodesics, paths along which the observed travel time is zero. Null geodesics basically map out spacetime. This is then entirely and totally distinct from any conception of "space expanding faster than light" - the question becomes meaningless.
Re: (Score:3, Informative)
For the love of fucking GOD.
http://science.slashdot.org/co... [slashdot.org]
Read the fucking comments, you cretin, and try and avoid labelling something as "nonsense" which you evidently don't fucking understand.
Re:Still nonsense (Score:4, Informative)
Although he is a bit abusive I'd cut the AC a bit of slack; your question/comment has been asked several times on this thread and in past ones. The short answer is that space itself can expand faster than the speed of light and so events we observe from a long time ago can be further than c times the time it took for the light to get here. Even events occurring 'now' from regions in space expanding away from us faster than c will eventually become observable to us, although the concepts of distance and time and 'now' can get really tricky under General Relativity. It is all prescribed by General Relativity, or more properly, by some of the easier solutions of the General Relativity field equation which appear to apply to our Universe. You can't use intuition from Special Relativity when the distances and times involved get cosmological. Sorry I don't have a good reference right now, but it's all in Wikipedia (try General Relativity or Hubble Constant or Age of the Universe, maybe). I looked it all up a while back when I got burned (on /.) using my Special Relativity intuition where it didn't apply.
Re: (Score:2)
Re: (Score:2)
Hyper Inflation lasted until the universe was about the size of a basketball.
It's statements like these that just scream out for an actual explanation. How can anyone possibly know that the size wasn't a bowling ball or a softball instead?
Although the answer seems to be "we'll bludgeon you in the face with math about 3 powers above what you understand until your eyes glaze over and you accept it." How much different is that than giving no explanation at all? Discuss :)
Re: (Score:2)
i prefer "God wills it"
Re: (Score:2)
Big fan of Starts with a Bang for many years, I must ask Ethan why cosmologists have ruled out the idea that our universe is the interior of a black hole. Neil deGrasse Tyson claims Einstein's equations can be interpreted to mean there is a different universe inside a black hole but he doesn't elaborate. If anyone else knows of a good reason as to why our universe can't be the interior of a black hole then I'd love to hear it.
Would that make any difference to us if it was?
Re: (Score:2)
Re: (Score:2)
Spoken like a true AC.