Is the universe finite or infinite

Mar 27, 2015 by Fraser Cain, Universe Today
Two possibilities 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.

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.

Read more at: http://phys.org/news/2015-03-universe-finite-infinite.html#jCp
See video too.
 
In our human 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.

I don't get it. If there was a Big Bang, and it was 13.8 billion years ago, then wouldn't we, at maximum, be on the edge of the universe, and wouldn't light then be coming at us from the origin 13.8 billion years ago in only one direction? The maximum diameter I could imagine (assuming the expansion to be spherical and occurring at light speed) of the universe would be 2 x 13.8 = 27.6 billion light years.

Of course, the expansion can't currently be occurring at light speed, and so the diameter of the universe would presumably be less than 27.6 billion light years.

Obviously, I've got something wrong somewhere. Can anyone explain what the heck he is saying? How could anything be more than 27.6 billion light years away if there was a Big Bang?
 
Obviously, I've got something wrong somewhere. Can anyone explain what the heck he is saying? How could anything be more than 27.6 billion light years away if there was a Big Bang?
Maybe it has something to do with Benghazi?? There's been countless Republican hearings on Benghazi.

My Best,
Bertha
 
In our human 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.

I don't get it. If there was a Big Bang, and it was 13.8 billion years ago, then wouldn't we, at maximum, be on the edge of the universe, and wouldn't light then be coming at us from the origin 13.8 billion years ago in only one direction? The maximum diameter I could imagine (assuming the expansion to be spherical and occurring at light speed) of the universe would be 2 x 13.8 = 27.6 billion light years.
It's all about speed. The speed at which space expanded was many times the speed of light during the " inflationary epoch".
Triggered by the symmetry breaking that separates off the strong force, models suggest an extraordinary inflationary phase in the era 10-36 seconds to 10-32 seconds. More expansion is presumed to have occurred in this instant than in the entire period ( 14 billion years?) since.

The inflationary epoch may have expanded the universe by 1020 or 1030 in this incredibly brief time. The inflationary hypothesis offers a way to deal with the horizon problem and the flatness problem of cosmological models.


Lemonick and Nash in a popular article for Time describe inflation as an "amendment to the original Big Bang" as follows: "when the universe was less than a billionth of a billionth of a billionth of a second old, it briefly went through a period of superchanged expansion, ballooning from the size of a proton to the size of a grapegruit (and thus expanding at many, many times the speed of light). Then the expansion slowed to a much more stately pace. Improbable as the theory sounds, it has held up in every observation astronomers have managed to make."
inflat2.gif

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/planck.html

Of course, the expansion can't currently be occurring at light speed, and so the diameter of the universe would presumably be less than 27.6 billion light years.
Why presume it can't be? Beyond the observable universe the speed of expansion is not known.

Obviously, I've got something wrong somewhere. Can anyone explain what the heck he is saying? How could anything be more than 27.6 billion light years away if there was a Big Bang?
One thing the Big Bang has nothing to do with is how fast space expanded which it did at a speed greater light. That name is just a title for the moment of everything coming into existence. Think of expansion this way. Here are 2.
1. Time is 10-^32 seconds and space is expanding many X times the speed of light. How many times the speed of light is that? We don't know.
2. Time is present and space is expanding at http://www.cnn.com/2014/04/08/tech/innovation/universe-expansion-astronomers/. That's how this universe could be finite or infinite in size.
There are 3 epochs of inflation. Here's another commonly seen graphic.
800px-History_of_the_Universe.svg.png
"History of the Universe" by Yinweichen - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/F...e.svg#/media/File:History_of_the_Universe.svg
Vectorised version of File:HistoryOfUniverse-BICEP2-20140317.png http://bicepkeck.org/visuals.html The bottom part of this illustration shows the scale of the universe versus time. Specific events are shown such as the formation of neutral Hydrogen at 380 000 years after the big bang. Prior to this time, the constant interaction between matter (electrons) and light (photons) made the universe opaque. After this time, the photons we now call the CMB started streaming freely. The fluctuations (differences from place to place) in the matter distribution left their imprint on the CMB photons. The density waves appear as temperature and "E-mode" polarization. The gravitational waves leave a characteristic signature in the CMB polarization: the "B-modes". Both density and gravitational waves come from quantum fluctuations which have been magnified by inflation to be present at the time when the CMB photons were emitted. National Science Foundation (NASA, JPL, Keck Foundation, Moore Foundation, related) - Funded BICEP2 Program http://bicepkeck.org/faq.html
 
It's all about speed. The speed at which space expanded was many times the speed of light during the " inflationary epoch".
Perhaps. But it's all just speculation. As for the expansion, where/how did the "emptiness" that the universe is expanding into originate?
 
Perhaps. But it's all just speculation. As for the expansion, where/how did the "emptiness" that the universe is expanding into originate?
Of course it is all speculation that's the fun of it. Those are serious questions, but the author's intent I think is to have fun. Just imagine if this will universe is infinite there are an infinite number of you reading this.
 
Perhaps. But it's all just speculation. As for the expansion, where/how did the "emptiness" that the universe is expanding into originate?
I don't know. Why is there so much "emptiness" in Crispy Cream donuts? 0.o I think it's an Atheist plot.

My Best,
Bertha
 
Of course it is all speculation that's the fun of it. Those are serious questions, but the author's intent I think is to have fun. Just imagine if this will universe is infinite there are an infinite number of you reading this.
I'm all for that sort of fun. However there are many who forget/ignore that it's speculation. Even you opine that those are "serious questions." They maybe to you and some others, to me they're silly fun. And no - infinite space doesn't mean an infinite "number" of people.
 
I'm all for that sort of fun. However there are many who forget/ignore that it's speculation. Even you opine that those are "serious questions." They maybe to you and some others, to me they're silly fun. And no - infinite space doesn't mean an infinite "number" of people.
I shouldn't argue with someone that knows the answers. So I ain't gonna.
 
Couldn't it be both? Fractals are both finite and infinite. In a fractal it is not the absolute size of anything that matters but the relationship of variously sized and proportioned spaces and boundaries.

I find it interesting that the radius of a black hole of the mass of the universe happens to be 13.7 billion light years which is about the alleged age of the universe is supposed to be. I can't help but think that's not a coincidence and that spacetime must somehow warp back in on itself.

If the universe is a fractal then it's apparent size or apparent granulation at the Planck length could just be the vanishing point from out current zoom level perspective.
 
Gonna only discourse with yourself then?

You do sometimes have a on overly mater-of-fact way of condescendingly opining that seems to shut down productive debate rather than stimulating it. I say this knowing I'm guilty of the same thing from time to time.
 
You do sometimes have a on overly mater-of-fact way of condescendingly opining that seems to shut down productive debate rather than stimulating it..
Sorry your incorrect. I often have an overtly matter-of-fact way of pointing out things that shut down unproductive debate.
 
I think something Arouet said was probably right. I apologise if I've misrepresented it. but "no matter what you prefer eternal consciousness etc. Something always has to have existed"
 
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