Talk:Universe

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Former good article Universe was one of the Natural sciences good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
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Universe and reality[edit]

The universe is certainly part of reality--but is it the totality of reality? The opening paragraph of this article seems to indicate that it is. In particular, I'm talking about the sentence, "Similar terms include the cosmos, the world, reality, and nature." First, I find this sentence redundant because universe was already clearly defined before it. It's redundant as far as that's concerned unless the editor is making an attempt to lump "universe" in with "reality," as though the universe and reality were synonymous. Perhaps they are and perhaps they aren't. The terms are certainly synonymous to the naturalist, but that isn't a neutral position. 24.128.244.108 (talk) 06:05, 6 June 2014 (UTC)

It doesn't say the "universe" is synonymous with "reality", Different terms have been used in history and in everyday discourse to discuss the concept we now call the "universe" For example the word "World" was used extensively in Western philosophy to mean "universe" (particularly before it was understood there were other "worlds"). Some of the terms from the sentence are also used in dictionary definitions of "universe". We've had a lot of discussion on this page already about the philosophical meaning of "universe". I think it's fine the way it is. --ChetvornoTALK 08:33, 6 June 2014 (UTC)

The opening paragraph defines the universe as a physical manifold which is true; that's what it is. However, at the end of the paragraph a laundry list of words are used and we're told that these are all similar to what the universe--a physical manifold--is. One word in the list is "reality." But reality encompasses absolutely everything that is real or actual, which would include even the supernatural (e.g., God). The problem with this is the supernatural is by definition a category of being that transcends the universe or nature. So there's a glaring problem here unless one holds the belief that there is no such thing as a category of being outside of nature, that naturalism is true, that the universe IS reality, and not merely a stratum of reality. 24.128.244.108 (talk) 09:07, 6 June 2014 (UTC)

And that is why it says "similar" and not "equivalent", i.e. there is overlap in how the terms are used, and within a certain POVs (but not others) they could even be used as synonyms.TR 09:19, 6 June 2014 (UTC)

Similar how though? Reality encompasses everything that is real or actual. The universe encompasses all physicality. So in what way is "reality" and "universe" similar? Calling these two words similar is like calling the set of natural numbers and the set {1, 2, 3} similar. I guess they're similar in the sense that they're both sets, but that's not worth noting. I don't think these two words are similar in any way or to be more modest: in any meaningful way. For the sake of my next point, let's say they're similar. How similar are they? That isn't explained at all, which makes things confusing and ambiguous for the reader. There are people reading the opening paragraph, being taught that the universe is spacetime or all physicality, and then they go on to read that this is similar to reality. But when one investigates this claim by clicking on reality they find that reality is much bigger than the universe--or at least there is the possibility that it is.

There seems to be something fishy going on here. One problem is many of the editors here at Wikipedia don't have any formal training in the topics that they're editors for--so one see them doing silly things like comparing "reality" with "the universe." A person with a little training in science and philosophy wouldn't make such a mistake in a so-called encyclopedia that is supposedly neutral, unless they were purposely trying to push a certain viewpoint like naturalism. 24.128.244.108 (talk) 09:42, 6 June 2014 (UTC)

A wrong use of "infinite"[edit]

This article states "The size of the Universe is unknown; it may be infinite." Yet it also states " Observations of supernovae have shown that the Universe is expanding at an accelerating rate." Now I'm no Einstein but I know that if the Universe had a beginning in the big bang and we are now 13.8 billion years in, It must be really big, but by definition cannot be infinite, because infinity is defined as "without limit". Please this is really simple and I was thinking about how it didn't make sense after reading. It can't be infinite regardless of how quickly it has been expanding for 14 billion years.

What is actually happening is a non-terminating process, space is continually growing larger, Yet it's not infinite because each individual light year, or mile, or foot, or inch etc. is finite and is achieved in a finite number of steps or time. Rather, the expansion of the universe "Approaches infinity". Yet, it cannot currently be infinite, not even in speculation (according to the previous mentioned facts of this article).

In fact, nothing in our universe can currently be infinite because time itself had a beginning in the big bang and terminates up to this very moment. For some physical property of our universe to have "no limit" and have a beginning at some point... time itself would have to stop completely - Only then will you never reach an end. The absence of time is true infinity.

Infinity is an abstract concept that cannot be observed in nature. Thanks. I hope this gets cleared up.

ps: This applies to the observable and unobservable universe. Carb0nshell (talk) 06:32, 30 August 2014 (UTC)

That isn't presently known. Available evidence gently *suggests* that the universe is spacial finite (maybe, or maybe just our local bubble is spatially finite...could go either way), but it doesn't say much about whether or not it is temporarily finite or infinite. Remember, something only has to be infinite in one direction (ie eg, a number life from 0 to infinity) to be infinite. So even if the universe could be said to have had a conventional beginning - a singularity popped into existence and instantly expanded - and it could still be just like that number line. It could have had a set beginning, go on forever, and be infinite in the direction of the future. And in that case it would be infinite, just like that number line. — Gopher65talk 12:35, 30 August 2014 (UTC)


I think you [(Carb0nshell)] are mistakenly thinking of the universe as a simple expanding sphere. Read this: Shape_of_the_universe- "According to cosmologists, ... the shape of the universe is infinite and flat, but the data are also consistent with other possible shapes". Bhny (talk) 13:27, 30 August 2014 (UTC)
A spatially infinite universe does not necessarily follow from the non-detection of curvature in the local universe. The article you link to actually talks about that a bit. Basically, if we detect the local universe to be "flat", that tells us nearly nothing about the shape or size of the universe. It's only if we detect curvatures that we can really start to speculate. This is (among other reasons) because any shape universe will appear flat if it is much larger than our local observable universe. All we can really say from our current measurements is exactly what this article says: "The size of the Universe is unknown; it may be infinite." That is literally the entirety of our (relatively certain) knowledge in this area. — Gopher65talk 15:40, 30 August 2014 (UTC)
Sorry by "you" I meant Carb0nshell, who may be using a balloon metaphor for the expanding universe. Bhny (talk) 19:25, 30 August 2014 (UTC)
The universe has been expanding for billions of years. We could mentally freeze this current moment in time and measure all of the finite miles back to the center. If we did this, we would get a concrete number, not infinity.
Also, remember: The future hasn't yet happened. Our timeline terminates, or ends, or stops at the most recent moment of present time. (its constantly being pushed froward, as time moves on). Infinite would mean the future already existing. Otherwise we only "approach" infinity with each passing second. Of course time is not infinite in the past direction - having an origin with the Big bang. So time has a beginning, and an end - that's constantly moving closer to infinity - yet it isn't infinite because it isn't complete. The number line is a good example of a complete infinity. Time - unlike the number line - is moving. Carb0nshell (talk) 09:25, 31 August 2014 (UTC)
Shape shouldn't matter here if the universe is somehow changing in any way through time. shape-wise, or really in any respect, then it can't be infinite. Carb0nshell (talk) 09:35, 31 August 2014 (UTC)
Carb, if you wouldn't mind, please put your comments at the bottom of all the other ones. It just makes it easier to follow the flow of conversation:).
As to your comment, I want you to ignore the universe for a moment, and we'll talk about infinities in general, since you seem to misunderstand the term.
Imagine this: you have an infinite set of numbers. This set, in fact: {0, 1, 2, 3, 4, 5... ---->}. This is the set of natural numbers. It starts at 0 and just keeps going forever. So it's an infinite set. Ok so far? Everyone has trouble with infinity. It's a weird concept.
Ok, so we have this infinite number set. You take out a single number, let's say "13", and you say, "ah hah! 13 is not an infinity! Therefore this isn't an infinite set of numbers!" ...Well 13 certainly isn't infinite, but that isn't the point. You can always extract a single number, or in fact any finite set like {13, 14, 15}, say, and that finite set will, of course, be finite. It will be finite because you specifically defined it as finite when you extracted it:). But just because you can pull out individual non-infinite numbers from that infinite set, that doesn't have any bearing on the set itself. The set of natural numbers is still infinite. It still goes on forever. For our purposes here, infinite basically means "goes on forever in at least one direction". In the case of the set of natural numbers, it has a definite beginning (either 0 or 1, depending on which you choose to start with), but it doesn't have an ending. It is only infinite in one direction.
So what does this have to do with the universe? Well, you said (paraphrased), "ah hah! The universe is 13 billion years old! That means it isn't infinite!" Well... no. That just means that you pulled out one number of an infinite set. Of course that particular number (that particular age) isn't infinity large, but it couldn't be. That's just not how infinities work. — Gopher65talk 15:23, 31 August 2014 (UTC)
You are also questioning the size of the spacial dimensions of the universe, claiming that it can't be infinite, because it started a finite time in the past. This is not the case. A universe could *poof* into existence and be infinitely large, or it could *poof* into existence and be a finite size. Universes are weird things. They don't follow the same rules as you and me, or as a balloon that you're blowing up.
I know scientists will say, "the universe expands like a balloon filling with air", but that's just an analogy. A really, really bad analogy, which gives people a lot of wrongheaded ideas about the universe.
I also think you're making the (very common) mistake of thinking of the Big Bang as an explosion which blew 'stuff' outward. If you make that assumption, then it totally makes sense that the universe would *have* to be finite, right? Because the explosion has been going on for 13.8 billion years, and no matter how fast the stuff is exploding outward, it is still finite in size.
But that's another really, really, really inaccurate analogy. That one isn't so much inaccurate as it is flat out wrong. The Big Bang didn't explode. And from the inside, even expansion is hard to see. Oh it "expanded", but an infinite object can still expand (see, infinities are weird, aren't they), either locally or as a whole. Just think about some points on our number line from the comment above: {12, 13, 14}. {40, 41, 42, 43}. {60, 61, 62, 63}. {1000000, 1000001, 1000002}. Each individual point on the number line, both present and future, is growing larger. But the number line as a whole is infinite. Weird, right? That's not an exact analogy either, but I don't think there are any exact analogies for the universe;).
I'm not sure I can properly explain to you exactly why the universe might be infinite (it's complicated), but I hope I've been successful in helping you see some of the flaws in your logic. — Gopher65talk 15:38, 31 August 2014 (UTC)
I have one last comment about how freaking weird the concept of infinity is. Imagine the set of natural numbers again. We'll use the version without 0 this time, for simplicities sake. {1, 2, 3, 4, 5, 6... ---->}. Now, imagine a second number line where we count by twos instead of by ones. {2, 4, 6, 8, 10, 12... ---->}. Both sets go to infinity. They're both infinite. But the second set, the one that counts by twos, is twice as large as the first set. No really, the second infinity is (provably) 2x the size of the first infinity. This isn't a trick. It really is. You see, infinities are never ending, but that doesn't mean they're all the same. Some infinities are... bigger... I guess, than others. We don't really have words to describe that. Bigger doesn't really work there, does it? But that's the way it works. One last time: infinities are weird;). — Gopher65talk 15:45, 31 August 2014 (UTC)
Our arguments all boil down to the structure of time. If the future is some construct that already exists out there, just waiting for us to arrive at its pre-built location, then your logic could work. I don't think most people see time as pulling random numbers off of an infinite number line, but rather as the inevitable progression into the future with the passing of present events into the past. Maybe, however, we do need to give science more time before changing this article. Pun intended.— Carb0nshell (talk) 19:40, 1 September 2014 (UTC)
No, cosmologists don't see time like that. Time is a dimension like the spacial dimensions, and like them had its origin at the Big Bang. The Big Bang is a singularity, a "coordinate" at which time and space lose meaning. Since all world lines originate at the Big Bang there is no meaning to the time "before" the Big Bang. That is also why the Universe could have always been spacially infinite, and yet have a beginning, in opposition to your argument, Carb0nshell Think of a movie of the Universe expanding, played backwards. The distance between any two objects, such as galaxies, gets smaller, until at the Big Bang the distance between any two objects goes to zero. ANY two objects, no matter how far apart they originally were. ALL distances go to zero. So the Universe could be spacially infinite a moment after the Big Bang. You can't apply normal intuition about distance and time to the Big Bang itself, it is inconsistent, like dividing by zero. --ChetvornoTALK 20:47, 2 November 2014 (UTC)

To address the very first comment in this section: The universe could quite possibly be infinite in extent even though only a finite amount of time has passed since the Big Bang. Even in 1-dimensional space (a line), the velocity field dx/dt = x2 results in particles going off to infinity in a finite amount of time. (And like that field, we know that masses are moving away from us faster, the farther away they are from us.)Daqu (talk) 13:59, 21 November 2014 (UTC)

Recent addition to introduction on multiverses[edit]

There seems to be an incipient edit war over the addition of a paragraph to the introduction saying that the terms "multiverse" or "many universes" are unscientific. --ChetvornoTALK 04:51, 1 September 2014 (UTC)

My feeling is, first, regardless of the validity of this point of view, it contradicts the sourced sentence at the end of the introduction mentioning multiverses, as well as the sourced section Universe#Multiverse theory. To add this paragraph, it needs to be sourced, and the sections of the article on multiverses should be deleted for consistency. Second, the paragraph strays into an off-topic rant on neologisms, which should be deleted. Third, the issue of whether the "multiverse" hypothesis should be included in this article is controversial and has been argued ad infinitum on this Talk page before; it should be discussed on this page before changes are made to the article. --ChetvornoTALK 04:51, 1 September 2014 (UTC)
I agree with with all your points, in fact I think it's quite over the top, thank you.—Machine Elf 1735 19:58, 1 September 2014 (UTC)

I have never understood why, if universe is defined as everything, "multiverse" isn't an oxymoron. 97.64.209.102 (talk) 21:04, 10 October 2014 (UTC)Terry Thorgaard (talk) 21:05, 10 October 2014 (UTC)

This situation happens over and over again in science; when the definition of a concept gets expanded due to scientific discoveries, new words (neologisms) have to be invented to distinguish the new meaning from the old meaning. In the history of Western philosophy the word "World" used to have a similar meaning to "Universe". Then the early astronomers discovered the stars and planets in the sky were not supernatural beings but physical objects ("worlds") like the Earth, so the word "World" slowly shifted in meaning from "everything there is" to mean "planet", one among many. So a new word was needed for "everything there is" and the word "Universe" came into use, which has come to mean our contiguous spacetime. If it turns out there are multiple universes, the word Universe is going to likewise shift in meaning to mean "one among many", and a new word will be needed for "everything there is", hence "multiverse". --ChetvornoTALK 23:30, 10 October 2014 (UTC)

Not infinite[edit]

I have researched the universe a topic and in my research it say that the universe is expanding so therefore it can not be defined as infinite.

Fun facts. The universe as far as we know has no edge an is not expanding from a singular point in space.


If I am wrong about any of there things I am talking about I would like to know what and why it is wrong. — Preceding unsigned comment added by ZeroKool00 (talkcontribs) 09:06, 27 September 2014 (UTC)

This was just discussed in the section two sections up from this one (and many, many times before this). Long story short, we don't even know what shape the universe is (current evidence points toward a "saddle" shaped, or infinite universe). Until we know the shape of the universe, we can't tell if it is spatially finite or infinite. Also, the universe may be temporarily infinite in one direction (the future). — Gopher65talk 12:48, 27 September 2014 (UTC)
I agree. In addition, ZeroKool00, a spacially infinite universe can still be expanding. Expansion just means the distance between any two sufficiently separate objects, such as clusters of galaxies, is increasing. --ChetvornoTALK 15:09, 27 September 2014 (UTC)

Confusion between a number and a function[edit]

In the Multiverse section, this sentence appears:

"Tegmark calculated our nearest so-called doppelgänger, is 1010115 meters away from us (a double exponential function larger than a googolplex)."

But this statement confuses a number— which is what 1010115 is — with a function, which 1010115 is not.Daqu (talk) 14:06, 21 November 2014 (UTC)

Fine tuning and the anthropic principle[edit]

The section on fine tuning contains the text:

"As such the conditional probability of observing a Universe that is fine-tuned to support intelligent life is 1. This observation is known as the anthropic principle and is particularly relevant if the creation of the Universe was probabilistic or if multiple universes with a variety of properties exist (see below). However, the observation that the chemistry of life may have begun shortly after the Big Bang, 13.8 billion years ago, during a habitable epoch when the Universe was only 10–17 million years old, may differ, in part, with the anthropic principle.[62][63]"

So, I don't understand how the possibility that the early universe had conditions conducive to life changes the conditional probability from 1 that the universe could support intelligent life. Maybe @Drbogdan can add an brief explanatory clause to the last sentence? Thanks, still wondering how we all got here, Grandma (talk) 19:57, 6 December 2014 (UTC)