# Thread: How big is the universe really?

1. I don't usually start threads in philosophy - and any I take part in usually result in a metaphorical crucifixion [of me] - so I'll humble myself to those to whom philosophy is a passion.

How big is the universe?

As I see it we can only decide by making comparisions from things within,
that is, imagine a picture which shows a set of outlines of shapes of differing colours - how big are the shapes? - a green square may be twice the area of the red triangle but neither can be referenced to anything outside.

2.

3. I think I'd go with "effectively infinite" for my answer, at this point. I'm not sure what the difference would be if the universe as a whole had bounds or not since our visible universe is the same size in either case.
But as for what's the actual size of the entire universe - the only answer I can honestly give is "I have no idea". Infinite doesn't seem like an intuitive answer if we consider a Big Bang but I know not to rely too much on intuition - so I have no idea.

4. Then you have to have to know how many directions that are possible, and cannot be disproven. Then you have to choose how many dots along each dimension and then you have to choose how many dimensions the universe has currently, and make the conclusion that the dots remained and has atleast the number of dimensions as particles has. and then you have to calculate the extension the universe would have with your current number of dots in your current number of dimensions, and then you find that it is eternal. Actually it is 4root(2eternities) but I don't think it'll end anyway.

5. I really really want to delete the previous post, the poster has ignored the fact that I am looking for the philosophical take/viewpoint on my question.
I have the power to delete yet would feel this might bring a charge of 'bias' - If I wanted to spray paint and measure the globular density I would have done so!

6. Whatever you do you are in it, you cannot travel beyond that which exists, being in that which do not exist is to say that that which do not exist, exists.

7. Originally Posted by Megabrain
I don't usually start threads in philosophy - and any I take part in usually result in a metaphorical crucifixion [of me] - so I'll humble myself to those to whom philosophy is a passion.

How big is the universe?

As I see it we can only decide by making comparisions from things within,
that is, imagine a picture which shows a set of outlines of shapes of differing colours - how big are the shapes? - a green square may be twice the area of the red triangle but neither can be referenced to anything outside.
13,7 billion light years in radius

even if the space extend into infinite the universe is 13,7 billion light years

8. The universe is a box of allready eaten chocolates and now we pay eternally for the eating.

9. Originally Posted by Zelos
13,7 billion light years in radius
even if the space extend into infinite the universe is 13,7 billion light years
There's really no way to to this for sure right now. Even assuming you are talking about the observable universe and not the entire universe(you didn't make the distinction but I'm assuming you mean observable universe?), you can't assume 13.7 billion.

Check this entry under "Misconceptions"(on the size of the universe) on Wiki:

 Misconceptions
Many secondary sources have reported a wide variety of incorrect figures for the size of the visible universe. Some of these are listed below.

13.7 billion light-years. The age of the universe is about 13.7 billion years, and nothing travels faster than light; does it not follow that the radius of the observable universe must be 13.7 billion light-years?
This reasoning might make sense if we lived in the flat spacetime of special relativity, but in the real universe, spacetime (not space!) is highly curved at cosmological scales, and light does not move rectilinearly. Distances obtained as the speed of light times a cosmological time interval have no direct physical significance. [3]

10. Does megabrain have to tell all of us? be philosophic!

11. Originally Posted by LeavingQuietly
Does megabrain have to tell all of us? be philosophic!
Are you suggesting that, after indicating twice I should re-iterate?

How many times do I have to appeal - if a member fails to understand the first two - what good a third or fourth?

12. Well I'm not sure what direction you want this to take. "How big is the universe" seems more a scientific question than a philosophical one to me. But your second paragraph is true - we measure size in reference to other things, but I'm not sure the point there.
If the conversation isn't going where you'd like perhaps you could take the reigns a bit?

13. Good point -

Yeah it's a dead end, we exist within this 'gasbag' we believe it's infinite but bounded - we know roughly how big it might be in comparison to everyday objects but that's as far as it goes - stupid thread - I'll move it to general discussion and let it take whatever course it does!

14. There's really no way to to this for sure right now. Even assuming you are talking about the observable universe and not the entire universe(you didn't make the distinction but I'm assuming you mean observable universe?), you can't assume 13.7 billion.
why i dont make the differens is becuase for cosmological people universe=observeble universe
the outside do they often call multiverse

15. The multiverse is not scientific.

As for space, I never understood why the Big Crunch was impossible.. If the power of the Big Bang `fuelsÂ´ the light leaving from that center of the universe, a Big Crunch would mean the return of the exact same energy.. I think that would mean that an event horizon would form just beyond where the light had formed, sucking it all back in.

Anyway, for me, itÂ´s all way to theoretical to take all that seriously. `Everything is energyÂ´ works for me.

Mr U

16. Originally Posted by HomoUniversalis
The multiverse is not scientific.

As for space, I never understood why the Big Crunch was impossible.. If the power of the Big Bang `fuelsÂ´ the light leaving from that center of the universe, a Big Crunch would mean the return of the exact same energy.. I think that would mean that an event horizon would form just beyond where the light had formed, sucking it all back in.

Anyway, for me, itÂ´s all way to theoretical to take all that seriously. `Everything is energyÂ´ works for me.

Mr U
big crunsh is impossible since the natural curvation of sapcetime has been determend to be flat wich indicate the matter-energy balance is insuffient to drag the entire unierse back toghater.

multiverse isnt scientific yes so is everything else outside the universe but im simply stating how they refer to things

17. comparing with things within...
well the distance between here and the next star is a big distance.
compared with the distance between us and the nearest galaxy makes the distance between us and the nearest star seem small.
a distance that spans the length of the universe would make all the other, well most of, the other distance comparisons seem small. if these comparisons to us still seem big then the answer to your question would seem to be that space is big. very big.

18. The universe is simply too big to discribe... In my oppinion it is endless either way you look at it. Or at least infinite from a human standpoint. The distance cannot really be percieved by humans for it is far to big even for the imagination.

19. Originally Posted by winterlord
The universe is simply too big to discribe... In my oppinion it is endless either way you look at it. Or at least infinite from a human standpoint. The distance cannot really be percieved by humans for it is far to big even for the imagination.
youre wrong universe is finite with 13,7 billion light year the multiverse can on he other hand be infinite

20. Originally Posted by Zelos
Originally Posted by winterlord
The universe is simply too big to discribe... In my oppinion it is endless either way you look at it. Or at least infinite from a human standpoint. The distance cannot really be percieved by humans for it is far to big even for the imagination.
youre wrong universe is finite with 13,7 billion light year the multiverse can on he other hand be infinite
And equally it could be infinitely small - the same size as it was at the big bang - we'll never know - expansion could, conceivably be, an illusion, since we cannot have, as there is not, an outside view!

21. Originally Posted by Megabrain
Originally Posted by Zelos
Originally Posted by winterlord
The universe is simply too big to discribe... In my oppinion it is endless either way you look at it. Or at least infinite from a human standpoint. The distance cannot really be percieved by humans for it is far to big even for the imagination.
youre wrong universe is finite with 13,7 billion light year the multiverse can on he other hand be infinite
And equally it could be infinitely small - the same size as it was at the big bang - we'll never know - expansion could, conceivably be, an illusion, since we cannot have, as there is not, an outside view!
you can be inside the box and yet know something is outside the box

22. Originally Posted by wallaby
comparing with things within...
well the distance between here and the next star is a big distance.
compared with the distance between us and the nearest galaxy makes the distance between us and the nearest star seem small.
a distance that spans the length of the universe would make all the other, well most of, the other distance comparisons seem small. if these comparisons to us still seem big then the answer to your question would seem to be that space is big. very big.
from our perspective, the KNOWN universe is about 14.4 BLY in all directions from where we are. thats 186,200 miles times 60 sec/min times 60 min/hr times 24 hr/day times 365 day/yr and times 14.4 billion. then times two or each direction. our sun is about 8 light minutes, our planet 26,000 around the equator and your car maybe 20 feet away.

the unknown universe or that beyond our sight is speculative. any one person can guess, my view it should be at least twice what we now see and may see with new versions of Hubble, in about 2012. we do know that this known universe has substantially increased in thought over the past 2-300 year, even some since the 1950's.

most of those stars you see are in our own galaxy, the Milky Way and some are even other galaxy, not just one star but millions or billions of stars seen as one light.

23. Originally Posted by Zelos
youre wrong universe is finite with 13,7 billion light year the multiverse can on he other hand be infinite
What the effing heck is a multiverse? A universe of all universes, maybe? Seems like a linguistic muddle - surely the word "universe", in a general sense, refers to all that there is?

How can you have a multiplicity of "all that there is"? (As you see, I'm no philosopher!)

24. The New Shorter Oxford English, Page 1857

Quote:

Multiverse: "The universe considered as lacking order or a single ruling and guiding power".

25. Originally Posted by Zelos
youre wrong universe is finite with 13,7 billion light year the multiverse can on he other hand be infinite
This isn't correct. Because of the expansion of space the observable universe is far greater than 13.7 billion years. A galaxy which emitted a photon towards us 13.7 billion years ago is actually much farther away now than when that photon was released so the observable universe is much bigger than 13.7 billion years though I'm not sure what the numerical estimate is. It's sort of hard to discuss without defining the time frame you want to talk about. But the observable universe is greater than 13.7 billlion light years in radius.
In a sense, the photon travelled 50 billion (or whatever) light years in only 13.7 billion years and it has more to do with the expansion of space than the actual distance traversed by the photon due its own movement.

26. Originally Posted by Megabrain
Multiverse: "The universe considered as lacking order or a single ruling and guiding power".
Then I'm definitely not a philosopher. In fact I must be dim, because I don't even understand that definition. Oh well...*crawls back to math, tail down*

27. Originally Posted by Guitarist
Originally Posted by Zelos
youre wrong universe is finite with 13,7 billion light year the multiverse can on he other hand be infinite
What the effing heck is a multiverse? A universe of all universes, maybe? Seems like a linguistic muddle - surely the word "universe", in a general sense, refers to all that there is?

How can you have a multiplicity of "all that there is"? (As you see, I'm no philosopher!)
This isn't correct. Because of the expansion of space the observable universe is far greater than 13.7 billion years. A galaxy which emitted a photon towards us 13.7 billion years ago is actually much farther away now than when that photon was released so the observable universe is much bigger than 13.7 billion years though I'm not sure what the numerical estimate is. It's sort of hard to discuss without defining the time frame you want to talk about. But the observable universe is greater than 13.7 billlion light years in radius.
In a sense, the photon travelled 50 billion (or whatever) light years in only 13.7 billion years and it has more to do with the expansion of space than the actual distance traversed by the photon due its own movement.
the universe dont mean "everything there is" but for cosmology, wich this is, universe is for cosmology "the radius wich we are able to observe"
its a rather common confusion for normal people

28. Originally Posted by Zelos
the universe dont mean "everything there is" but for cosmology, wich this is, universe is for cosmology "the radius wich we are able to observe"
its a rather common confusion for normal people
That's the universe I'm talking about. If you go look at the light from the farthest galaxy it's more than 13.7 billion light years away because of the expansion of space. But, like I said, it depends on WHEN you are talking about. If you mean "Right NOW how far away is the farthest galaxy we can see" then it's far greater than 13.7 billion light years. But, we're not seeing that galaxy as it is NOW of course. If you mean "How far away was the farthest galaxy when it emitted the light we see" then I think you can answer 13.7 billion light years. I think that's a less useful answer though because space has expanded considerably in that time.
I think though that it's preferable to say "visible universe" or "observable universe" because on forums like this we DO talk about the entire universe probably more often than the observable one.

29. its allways 13,7 billion years since at that distance is the expansion go faster than the speed of light and we cant see it then, but what ever before this limit is possible to see, just alot ore less redish :S

30. "Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." - DA

Being a novice in these fields, I would love to hear more from everyone

31. Is space big or are we just very small...

32. okey mega lets not get philosophical.

both are true

33. Originally Posted by Megabrain
Is space big or are we just very small...
Id like to think that the size of life (on average) - that is, complex organisms such as ourselves is in the middle as far as size goes. The universe is as big to us as the sub atomic realm is small.

34. Originally Posted by leohopkins
Originally Posted by Megabrain
Is space big or are we just very small...
Id like to think that the size of life (on average) - that is, complex organisms such as ourselves is in the middle as far as size goes. The universe is as big to us as the sub atomic realm is small.
the small
the big
and the middle
3 worlds
3 explinations
1 set of rules

35. two sets of rules, the small is governed by quanta, the large by the metre 8)

36. Seeing as this is the philosophical forum, i would have to answer with, how long is a piece of string?

37. LMAO! - At last a real answer!!!!

38. well could the universe be infinite as it is expanding and we know that galaxies farther away are moving faster away form us than closer ones. would there be a point where the actual galaxy itself approaches the speed of light and falls "over the edge" where we will never see it again because its photons are not traveling fast enough to reach us. This would imply that our visible universe will not change and the actual universe is much more than possibly imaginable where there is an unimaginable amount of mass beyond this light speed barrier.

39. 28 billion light years, maximum.

40. Originally Posted by Megabrain
two sets of rules, the small is governed by quanta, the large by the metre 8)
now yes, but i think that will change in the future

41. Originally Posted by Zelos
13,7 billion light years in radius
Actually, it's not that simple.

From Wiki

"Very little is known about the size of the universe. It may be trillions of light years across, or even infinite in size. A 2003 paper[19] claims to establish a lower bound of 24 gigaparsecs (78 billion light years) on the size of the universe, but there is no reason to believe that this bound is anywhere near tight. See shape of the Universe for more information.

The observable (or visible) universe, consisting of all locations that could have affected us since the Big Bang given the finite speed of light, is certainly finite. The comoving distance to the edge of the visible universe is about 46.5 billion light years in all directions from the earth; thus the visible universe may be thought of as a perfect sphere with the earth at its center and a diameter of about 93 billion light years.[20] Note that many sources have reported a wide variety of incorrect figures for the size of the visible universe, ranging from 13.7 to 180 billion light years. See Observable universe for a list of incorrect figures published in the popular press with explanations of each."

Yes, the universe probably is 13.7 billion years old, but read about Cosmic Inflation:
http://en.wikipedia.org/wiki/Cosmic_inflation

42. Now can you you substantiate that from a non-wiki source? as good as wiki is, it is compiled by amateur scientists, on such an important matter verification is required.

43. Yes, I agree. Try this, with comments by Neil Cornish, an astrophysicist at Montana State University.

Space.com:

http://www.space.com/scienceastronom...ay_040524.html

"The universe is about 13.7 billion years old. Light reaching us from the earliest known galaxies has been travelling, therefore, for more than 13 billion years. So one might assume that the radius of the universe is 13.7 billion light-years and that the whole shebang is double that, or 27.4 billion light-years wide.

But the universe has been expanding ever since the beginning of time, when theorists believe it all sprang forth from an infinitely dense point in a Big Bang.

"All the distance covered by the light in the early universe gets increased by the expansion of the universe," explains Neil Cornish, an astrophysicist at Montana State University. "Think of it like compound interest."

Need a visual? Imagine the universe just a million years after it was born, Cornish suggests. A batch of light travels for a year, covering one light-year. "At that time, the universe was about 1,000 times smaller than it is today," he said. "Thus, that one light-year has now stretched to become 1,000 light-years."

All the pieces add up to 78 billion-light-years. The light has not traveled that far, but "the starting point of a photon reaching us today after travelling for 13.7 billion years is now 78 billion light-years away," Cornish said. That would be the radius of the universe, and twice that -- 156 billion light-years -- is the diameter. That's based on a view going 90 percent of the way back in time, so it might be slightly larger."
_______

The point, as you will have noticed, is that whatever the diameter of the universe actually is, owing to the fact that space itself has been expanding since the Big Bang, it would have to be very much more than 13.7 billion x2 light years - and that's without taking into account any variation of Allan Guth's 'Cosmic Inflation Theory'.

44. I think that the universe is a Strange loop. There will be a point that when you scale things up large enough we will really be back to the very small. Probably have to do with B.Hs being so mysterious.
Just my intuition no real science based on this.

45. psynapse.
Intuitions are welcome in science. I can imagine that little progress would be made without them. If it was good enough for Einstein, well...The interesting thing is that, weird as Einstein's theories were, he refused to accept Heisenberg's Uncertainty Principal. Can't blame him; things just get weirder and weirder. I wouldn't be surprised if you turned out to be right. Reality is already proving to be that bizarre. Maybe the trick is to intuit the counter-intuitive.

OK, sorry, that's a digression from the 'the size of the universe'.

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