Thread: The visable universe % wise

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The visable universe % wise

Is there any estimates to what percentage the observable universe makes up as a whole? How much will we never see?
When the first light was released how big was the universe and what percentage of it would you be able to see?

2. Originally Posted by saintpaul
Is there any estimates to what percentage the observable universe makes up as a whole? How much will we never see?
When the first light was released how big was the universe and what percentage of it would you be able to see?
Welcome to BAUT, saintpaul.

No.
The visible universe is all we can ever see.
We don't know.

The reasons for these answers is that as the universe expands, the further away from us an object is the faster it is moving in relation to us; the parts of the universe beyond the limit of our observation are expanding so fast that the light from those parts will never reach us. So we have no way of knowing what, if anything, is beyond that observable limit.

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There is no indication at all of a maximum possible size. Some theorists
say that the Universe could be infinite in extent. I personally believe that
the matter involved in the cosmic expansion (the Big Bang) cannot be
infinite because that would violate causality. But I have no problem with
spacetime being infinite.

From what we can see of the visible part of the Universe, we get some
hints of the minimum possible size. Some analysis indicates that the
Universe must be at least several orders of magnitude larger than what
we can see.

The Universe is absurdly big.

During most of the history of the Universe, the amount of matter included
in the part that would have been visible to a hypothetical observer would
have increased over time. Now, with the acceleration of the expansion,
which has apparently been going on for the last few billion years, it must
be reducing, as the most distant galaxies move beyond our "horizon".

Sorry that I can't provide ay hard numbers.

-- Jeff, in Minneapolis, 1/2 mile from St. Paul

4. Originally Posted by saintpaul
Is there any estimates to what percentage the observable universe makes up as a whole? How much will we never see?
When the first light was released how big was the universe and what percentage of it would you be able to see?
From what I've read in papers like Applications of Bayesian model averaging to the curvature and size of the Universe the universe is
probably at least 250x as large as our visible portion.

Since the rate of expansion is currently increasing our view of the universe will steadily grow smaller percentage wise.

The CMBR was emitted only about 42 million light years away. The distance is now ~46 billion light years away now and the light has been travelling for ~13.75 billion light years.

At the time of the CMBR emitting you could see basically zero distance in astronomical terms. After that the distance grew with time but expansion has out pace that over all.

IE at the time of surface of last scattering the universe the universe would have have a glow of like the sun but this quickly expanded out and quickly red shifted to non visible light.
This began a period of time sometime referred to as the dark ages because there where no stars yet. As my understanding goes when the first stars started to ignite the universe
was within a order of magnitude of its current size but even with this as the case the universe seems to have started once again accelerating its rate of expansion.

If you accept the 251x the size of the visible universe then at the time release of the CMBR the universe was at least 10 billion light years across, don't like that word but. The amount of time that light had to travel was 0 so you couldn't see anywhere. As the first stars started forming the universe had already expanded by a few hundred times and this was only in a blink of an eye in cosmological terms. Over the next 13.75 billion years the universe has expanded to a total of about 1000x its size at the time of the release of the CMBR.
Last edited by WayneFrancis; 2011-May-19 at 01:58 AM. Reason: Fixed typo Grey pointed out.

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"The universe is
probably at least 250x as large as our visible portion."

"The Universe is absurdly big."

Thanks for the replies, I do imagine the wheels within wheels vision where what we can see is a fraction of a great wheel or sphere. Where the cosmic web is just a spoke on a wheel!

6. Originally Posted by saintpaul
Is there any estimates to what percentage the observable universe makes up as a whole? How much will we never see?
"...the entire universe is expected to be at least 1023 times larger than the observed universe! ...if the inflationary theory is correct, then the observed universe is only a minute speck in a universe that is many orders of magnitude larger." - Alan Guth

Cosmic inflation answers several vexing questions about the Universe, but we're still not real sure it's correct. We do know that Guth's original version had some problems, and it has been superceded by other versions. Many other versions. Nevertheless, there are apparently theoretical reasons to come up with "1023 times larger." Of course, this is a really tough question that we really don't know the answer to.

7. Originally Posted by WayneFrancis
...you could see basically zero distance in astrological terms.
Astronomical terms. But other than that error, an excellent post.

8. Originally Posted by Grey
Astronomical terms. But other than that error, an excellent post.
Actually, he's probably correct. Astrologically we can see basically zero.

9. Originally Posted by Grey
Astronomical terms. But other than that error, an excellent post.
Man I was full of typos yesterday ...thanks for the correction.

10. Originally Posted by Amber Robot
Actually, he's probably correct. Astrologically we can see basically zero.
hehehe

11. Originally Posted by Jeff Root
There is no indication at all of a maximum possible size. Some theorists
say that the Universe could be infinite in extent. I personally believe that
the matter involved in the cosmic expansion (the Big Bang) cannot be
infinite because that would violate causality. But I have no problem with
spacetime being infinite.l
Interesting.
How does infinite matter violate causality?

Couldn't it have been an infinite universe that is uniformly hot and infinitely dense before expansion starts?

An infinite universe will have some disturbing statistical properties though, that come from random infinity:
For the same reason that PI has my phone number in it, as well as all the photos that are stored on my camera's SD card (including one with me sticking my tongue out which I didn't take)
-the universe then will have to have an infinite number of me in it. Including an infinite number of me that just spelled the last word wrong. There will have to be an infinite numbers of Earths where WWII didn't happen, ... etc ..

While I don't LIKE the idea of that kind of a universe, liking or not is not really argument enough to dismiss it..
Can causality do that? ;-)

Peter

Interesting.
How does infinite matter violate causality?

Couldn't it have been an infinite universe that is uniformly hot and infinitely dense before expansion starts?

An infinite universe will have some disturbing statistical properties though, that come from random infinity:
For the same reason that PI has my phone number in it, as well as all the photos that are stored on my camera's SD card (including one with me sticking my tongue out which I didn't take)
-the universe then will have to have an infinite number of me in it. Including an infinite number of me that just spelled the last word wrong. There will have to be an infinite numbers of Earths where WWII didn't happen, ... etc ..

While I don't LIKE the idea of that kind of a universe, liking or not is not really argument enough to dismiss it..
Can causality do that? ;-)

Peter
But just as Pi is an infinite nonrepeating decimal, the universe may also be a nonrepeating infinity, with only one Earth and only one set of us.

13. Originally Posted by Noclevername
But just as Pi is an infinite nonrepeating decimal, the universe may also be a nonrepeating infinity, with only one Earth and only one set of us.
Correct

for example

3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 82148 08651 32823 06647

There is Pi to 120 digits

While Pi never goes into a repeating pattern you can find a repeat of patterns within Pi

Like I was to find all the instances of "14" in the first 120 digits
3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 82148 08651 32823 06647

or "79"
3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 82148 08651 32823 06647

But this does not mean all patterns will repeat even though patterns of greater length may repeat.

The bigger the pattern the further we would expect to look before finding it. In an infinite series like Pi you can pick any length for a pattern and find more then 1 instance of that length pattern but that
some other pattern of that length may be completely unique. For example I can make an infinitely long number $1.5\overline{216790348}$ only has the patern "5" in it once
even though it it infinitely long.

14. Originally Posted by Noclevername
But just as Pi is an infinite nonrepeating decimal, the universe may also be a nonrepeating infinity, with only one Earth and only one set of us.
It's because it is a non repeating infinity that it contains all possible sequences.
Portions of a non repeating sequence have to repeat themselsves. It is not possible to have it otherwise.
In fact, any sequence of numbers has to appear an infinite number of times.

If you have an infinite random number sequence therefore, sooner or later my phone number has to come up.
Because there's a finite number of digits to arrange into eight positions.

It would not only apply to numbers.
The earth is made up of atoms.
A finite number of atoms.
In an infinite universe therfore, statistically, any organisation of atoms would have to repeat eventually, no matter how unlikely.
It would also have to repeat an infinite number of times.

Peter

15. Originally Posted by WayneFrancis
But this does not mean all patterns will repeat even though patterns of greater length may repeat.
Ah, -If Pi digits are not truly random.

I picked Pi because I thought it was..
For a truly random sequence of numbers, any pattern will repeat itself an infinite number of times..

Peter

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Originally Posted by Jeff Root
There is no indication at all of a maximum possible size. Some theorists
say that the Universe could be infinite in extent. I personally believe that
the matter involved in the cosmic expansion (the Big Bang) cannot be
infinite because that would violate causality. But I have no problem with
spacetime being infinite.
Interesting.
How does infinite matter violate causality?
By being the same without having any reason for being that way.
The space and matter involved in the cosmic expansion have
properties that are the same everywhere, so they must have a
common origin. It is too much of a coincidence to imagine that
an infinite number of particles distributed through infinite space
each came into existence independently of every other by
chance. The matter participating in the cosmic expansion must
all have been in causal contact at the beginning, so it could not
have been infinite in extent.

Couldn't it have been an infinite universe that is uniformly hot
and infinitely dense before expansion starts?
There is no way it could become uniform in finite time.

-- Jeff, in Minneapolis

17. Originally Posted by Jeff Root
By being the same without having any reason for being that way.
The space and matter involved in the cosmic expansion have
properties that are the same everywhere, so they must have a
common origin. It is too much of a coincidence to imagine that
an infinite number of particles distributed through infinite space
each came into existence independently of every other by
chance. The matter participating in the cosmic expansion must
all have been in causal contact at the beginning, so it could not
have been infinite in extent.

There is no way it could become uniform in finite time.

-- Jeff, in Minneapolis
Can you present mathematical, observational and/or physical evidence for these statements?

18. Originally Posted by Jeff Root
The space and matter involved in the cosmic expansion have
properties that are the same everywhere, so they must have a
common origin.
That is approximately true for the observable universe. We don't know about the rest (infinite or otherwise).

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Originally Posted by Strange
Originally Posted by Jeff Root
The space and matter involved in the cosmic expansion have
properties that are the same everywhere, so they must have a
common origin.
That is approximately true for the observable universe. We don't
know about the rest (infinite or otherwise).
That is my point. We *do* know two things:

1) Everywhere cosmic expansion is occurring has properties in
common with everywhere else cosmic expansion is occurring.

2) If the Universe is infinite in extent, then those properties
cannot be the same everywhere. Which is to say that the
expansion cannot be occurring everywhere.

So either the cosmic expansion involves the entire Universe,
in which case the Universe is finite, or the cosmic expansion
does not involve the entire Universe.

-- Jeff, in Minneapolis

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Originally Posted by Noclevername
Originally Posted by Jeff Root
By being the same without having any reason for being that way.
The space and matter involved in the cosmic expansion have
properties that are the same everywhere, so they must have a
common origin. It is too much of a coincidence to imagine that
an infinite number of particles distributed through infinite space
each came into existence independently of every other by
chance. The matter participating in the cosmic expansion must
all have been in causal contact at the beginning, so it could not
have been infinite in extent.

There is no way it could become uniform in finite time.
Can you present mathematical, observational and/or physical
evidence for these statements?
I'd appreciate it if you narrowed the request down a bit.
Which of those statements do you want evidence for?

-- Jeff, in Minneapolis

21. Originally Posted by Jeff Root
2) If the Universe is infinite in extent, then those properties
cannot be the same everywhere. Which is to say that the
expansion cannot be occurring everywhere.
"not the same" != "not occurring" (as people here do like to ask for the math )

22. Originally Posted by Noclevername
the parts of the universe beyond the limit of our observation are expanding so fast that the light from those parts will never reach us.
Sorry if I'm being dim, but can this be true? Why would the light not reach us eventually?

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Strange,

If two regions of the Universe are experiencing similar
cosmic expansion, then they have "the same" properties.
Since the Universe has finite age, if it has infinite size,
then it cannot be the same everywhere. Which means
cosmic expansion like what we observe cannot be
occurring everywhere.

-- Jeff, in Minneapolis

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Perikles,

Light from distant galaxies will never reach us because the space
between us and them is expanding faster and faster all the time.
Instead of getting closer and closer to us, the light is getting farther
and farther away. The plain old cosmic expansion, as it was
presumed to be before 1998, would not cause this.

-- Jeff, in Minneapolis

25. Originally Posted by Jeff Root
If two regions of the Universe are experiencing similar
cosmic expansion, then they have "the same" properties.
[my bold] Similar.

Since the Universe has finite age, if it has infinite size,
then it cannot be the same everywhere.
Probably true. But it can be similar everywhere. It doesn't have to have, say, areas the size of the observable universe with no matter in. It just has to be inhomogeneous enough that it doesn't require all points to have been in causal contact at some point. It may be similar enough just because of the fundamental laws/constants of nature.

Which means
cosmic expansion like what we observe cannot be
occurring everywhere.
Cosmic expansion similar to what we observe could be.

On the other hand, at the very largest scales, the universe might be truly inhomogeneous. There may be an infinite number of volumes of all different sizes which contain anything from zero matter to billions of times more matter than out universe. In which case, some parts will be expanding faster than others, and others will be contracting.

But we can probably never do anything but speculate either way.

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I don't understand your focus on a distinction between "same" and
"similar". It isn't relevant.

Different parts of the visible Universe are obviously very similar.
They are the same in every way that matters as far as understanding
the causal connection to the Big Bang. Parts of the Universe that
are not visible to us might be less similar, but still part of the Big Bang,
participating in the cosmic expansion. In every way that matters for
understanding the causal connection to the Big Bang, they are also
the same. Some parts of the Universe might not be participating in
the cosmic expansion, because they were not part of the Big Bang.
Those parts of the Universe, if they exist, might never have been
causally connected to our part of the Universe. In that case, they
would have little in common. They would not be the same.

Parts of the Universe which are infinitely far apart could not be
causally connected, so they could not be the same. They could
not both be participating in the cosmic expansion that we see.

-- Jeff, in Minneapolis

27. Originally Posted by Jeff Root
Perikles,

Light from distant galaxies will never reach us because the space
between us and them is expanding faster and faster all the time.
Instead of getting closer and closer to us, the light is getting farther
and farther away. The plain old cosmic expansion, as it was
presumed to be before 1998, would not cause this.

-- Jeff, in Minneapolis
Thanks for that, I am still in pre-1998 mode, thinking that if a distant galaxy is receeding at a speed approaching c, but still less than c, eventually the light would reach us.

28. Originally Posted by Jeff Root
I don't understand your focus on a distinction between "same" and
"similar". It isn't relevant.
To my mind, they are completely different concepts. Not even similar I don't understand why you think the distinction is not relevant.

Different parts of the visible Universe are obviously very similar.
They are the same in every way that matters as far as understanding
the causal connection to the Big Bang.
Right, where "same" means sufficiently similar that they must have been causally connected at some point.

Some parts of the Universe might not be participating in
the cosmic expansion, because they were not part of the Big Bang.
Those parts of the Universe, if they exist, might never have been
causally connected to our part of the Universe.
Possibly.

In that case, they
would have little in common. They would not be the same.
But they might be similar. For reasons other than causal connection. For example, they may still be made up of familiar fermions and bosons, and the same laws of physics. In which case we might expect to see familiar stars and galaxies (with, perhaps, some subtle differences).

Or they may be sufficiently isolated and made up entirely of antimatter. Or strange matter.

Or, in that part of the universe the laws of physics might be very different; no weak interaction for example.

I just don't believe that one can make any argument from what we observe to the rest of the (unobservable) universe. My default assumption, until it can be shown otherwise, is that it goes on forever and is broadly similar everywhere - but not so similar ("the same") that it requires causal connection. On the other hand, I am not strongly attached to that point of view, it just seems to avoid having to invent anything new.

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Originally Posted by Strange
Right, where "same" means sufficiently similar that they must have
been causally connected at some point.
Yes yes yes yes yes. That will do.

Originally Posted by Strange
But they might be similar. For reasons other than causal connection.
For example, they may still be made up of familiar fermions and
bosons, and the same laws of physics. In which case we might
expect to see familiar stars and galaxies (with, perhaps, some
subtle differences).
If any region of the Universe had particles closely resembling
fermions and bosons, I would strongly suspect that it had been
causally connected with our part of the Universe at one time.
If it had particles that were unqualifiedly fermions and bosons,
I would say that it was virtually certain it had been causally
connected with our part of the Universe, with the caveat that
in an infinite Universe full of stuff, things are bound to be the
same in different places for no reason but chance.

Originally Posted by Strange
Or they may be sufficiently isolated and made up entirely of
antimatter. Or strange matter.
Anything made of antimatter or strange matter would just as
definitely have been causally connected with our part of the
Universe.

-- Jeff, in Minneapolis

30. Originally Posted by Jeff Root
I'd appreciate it if you narrowed the request down a bit.
Which of those statements do you want evidence for?

-- Jeff, in Minneapolis
You stated that it was "too much of a coincidence" that all matter in an infinite universe could come into existence "by chance". You stated that there was "no way" it could become uniform in finite time. Those will do.

Have you considered the possibility that the reason space and matter are the same everywhere is simply that that is the only configuration our universe's laws of physics will allow?

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