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Joe90
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18 May 2014, 3:39 pm

Everything I have ever come across has a beginning and an end in time and existence, even the ocean. But outer space is just something I can't get my head round. Everything has a mass, even if you don't know the mass, it's still there. Like if I put lots of balls into a bag without counting them, there will be a certain number of balls in the bag, even if nobody has counted them, it will still be that mass. Could be 24 balls, could be 30 balls, could be 21 balls. If I put a load more balls into the bag, it would be an even bigger mass of balls in the bag, even if I haven't counted, there is still that certain amount of balls inside. Do you get me?

But although nobody has ever counted how many miles (from the Earth I suppose) the whole of space is, nobody can even assume how many miles it is because it goes on forever. But surely it can't go on forever. As I thought, everything has a mass, and there must be an end to outer space somewhere. But even if there was, whats beyond it? Whatever is beyond, it still all goes on forever, although it's so hard to imagine. If no stars or moons or suns or planets or anything else existed, there still will be just....space. But there was no beginning to space either, it's just always been there. Ohh, so interesting, yet fascinating.

I hope ''mass'' is the right word? I know somebody here will give me a good answer. :)


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Kurgan
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18 May 2014, 3:47 pm

Outer space does not go on forever. The observable universe has a diameter of 93 billion lightyears.


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Eccles_the_Mighty
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18 May 2014, 4:27 pm

OK, I'm going to have a go at this but I might get it wrong, bear with me.

We've all seen the classic demonstration on TV of the way gravity distorts space/time using a rubber sheet and a couple of ball bearings. Put one in the middle and the other one orbits around because gravity distorts LOCAL space/time into a funnel shape.

Now expand this to encompass the entire universe, something which is very big and very heavy.

Gravity will contract the universe and distort it in the nth dimension until the entire universe is donut shaped. The important thing is that you cannot see this because we only exist in three dimensions and this is the mathematical equivalent of living on the surface of the donut.

You can now either carry out a thought experiment or go find a donut.

Set off from any point on the surface of the donut and in any direction, chances are that you will continue to travel over the surface for an infinite amount of time and never arrive at the same point. The same thing occurs with telescopes, light or radio waves are distorted and bent by the gravitational pull of the universe so that space appears infinite.

Our technology however is NOT infinite and with our present equipment we can see about 46 billion light years.


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1401b
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18 May 2014, 4:54 pm

Huh, I'm not an astronomer but I thought the observable universe had a radius of 13.7 billion light years, the maximum that we can see and therefore the presumed age of our universe.
Unless observable means something different than: the stuff we can see.

Space is defined by it's contents so once we get beyond the "edge" of our universe there are no more contents, therefore no more space to define, therefore no more distance therefore no "infinity."
Which is just semantics.

The idea of forever or infinity is rather pointless so I cope with it by simply assuming that if it's that far out there then there's probably nothing of interesting there or on the way there.
Meaning it's too boring to get to, either in a spaceship or in a thought experiment.

In the end I assume there isn't any infinity because there will always be some kind of change or another that we'll view as demarcations.

The concept of infinity (imo) is just mental masturbation -it's fun to think about.


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starvingartist
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18 May 2014, 5:01 pm

1401b wrote:
Huh, I'm not an astronomer but I thought the observable universe had a radius of 13.7 billion light years, the maximum that we can see and therefore the presumed age of our universe.
Unless observable means something different than: the stuff we can see.

Space is defined by it's contents so once we get beyond the "edge" of our universe there are no more contents, therefore no more space to define, therefore no more distance therefore no "infinity."
Which is just semantics.

The idea of forever or infinity is rather pointless so I cope with it by simply assuming that if it's that far out there then there's probably nothing of interesting there or on the way there.
Meaning it's too boring to get to, either in a spaceship or in a thought experiment.

In the end I assume there isn't any infinity because there will always be some kind of change or another that we'll view as demarcations.

The concept of infinity (imo) is just mental masturbation -it's fun to think about.


the light that we see when we look as far away as we can look (13.7 billion light years) has been travelling for 13.7 billion years--and during those many eons, the universe the light was travelling through has been expanding--so even though the light has been travelling for 13.7 years and therefore we say it came from 13.7 billion light years away, the universe that it travelled through in that time frame expanded to the size of 93 billion light years across. relativity is a funny thing when you're talking about extreme speeds (like light speed) and huge distances (like billions of light years).



Venger
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18 May 2014, 5:17 pm

I guess if you went out far enough into the universe you'd get to a point where you couldn't see any light from stars anymore though. And then send somebody a postcard with a totally-black photo on the front of it. :lmao:



mezzanotte
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18 May 2014, 6:27 pm

Humans evolved to comprehend matters of the Earth, because our survival depends on it. Equipped with only five senses and incredibly limited brains, we're not supposed to make sense of everything in the Universe. Just as an earthworm has not the slightest understanding of atomic bombs, we have almost no understanding of the Universe. Attempting to discuss the Universe in simplistic written languages is a joke, to be honest.



zer0netgain
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18 May 2014, 7:17 pm

I figure the best way to see it is that the "universe" is an empty void....observable or not. The "stuff" in the universe is expanding into that void, but the void goes on forever.

Mind-warping because you have to consider "nothing" to be "something" although it is nothing and you could say that the universe is only as big as the volume that it's substance contains at any given moment...like a balloon that swells when inflated and contracts when deflated.



MrOddBall
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19 May 2014, 3:40 am

So basically the universe has already ended but we're catching up to it ?



eric76
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19 May 2014, 3:47 pm

The universe may be open or closed. If it is closed, it is finite and if it is open it is infinite. Since the universe started out closed, if it is now infinite then there must have been some point in time when it went from finite to infinite. The thought of this is rather unsettling.

When you hear about the search for dark matter, they are looking for enough matter that would exert a sufficient gravitational force to keep the universe closed.

Assume that the universe is closed. Imagine being a two dimensional being on the surface of a sphere -- no matter which direction you travel, you can keep on going and going and going and never reach a boundary.

The difference between the universe and a sphere is that on a sphere, you are restricted to two dimensions while the universe would be three. So in the universe, no matter which direction you go, you will never reach a boundary.

As for the horizon aka "edge of the observable universe", this actually refers to the distance at which points in space are traveling faster away from us at the speed of light. Anything closer, the points are traveling slower than the speed of light. Anything further, the points are traveling faster than the speed of light from each other. Thus, anything past the edge of the observable universe cannot be observed because it is traveling away at faster than the speed of light.

How can this be? It's because the travel faster than the speed of light is not the result of accelerate the particles. You cannot apply enough force to a particle to make it go faster than the speed of light away from you. With infinite force, you could only get it to the speed of light.

In the case of the universe, it is not due to an acceleration of particles but do to the expansion of space between the points. Think of it like a nice, uniform balloon. As you blow up the balloon, points that are further away from each other will see a greater increase in distance between them than two points that are closer to each other.

The universe is like that. Two points that are one million light years apart will be traveling away from each other at half the speed of two points that are two million light years apart and at double the speed of two points half a million light years apart. If the distance is large enough, you will have points moving away from each other at the speed of light.



ruveyn
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19 May 2014, 6:55 pm

Kurgan wrote:
Outer space does not go on forever. The observable universe has a diameter of 93 billion lightyears.


That is the furthest we receive light signals. With space expanding faster and faster it is possible that there is stuff beyond that horizon but we can see it. If it is expanding faster than light and there is stuff there we can never receive the light.

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LupaLuna
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20 May 2014, 12:37 am

eric76 wrote:
Assume that the universe is closed. Imagine being a two dimensional being on the surface of a sphere -- no matter which direction you travel, you can keep on going and going and going and never reach a boundary.


That's not going to infinity. that's going in a circle. Yes, you can keep on going and going and going and never reach a boundary but all you will be doing is coming back to the same place over and over again.



eric76
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20 May 2014, 1:32 am

LupaLuna wrote:
eric76 wrote:
Assume that the universe is closed. Imagine being a two dimensional being on the surface of a sphere -- no matter which direction you travel, you can keep on going and going and going and never reach a boundary.


That's not going to infinity. that's going in a circle. Yes, you can keep on going and going and going and never reach a boundary but all you will be doing is coming back to the same place over and over again.


There are three choices: closed (positive curvature), flat (zero curvature), or open (negative curvature). If flat or open, then a traveler could not come back on himself. If closed, he can.



naturalplastic
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20 May 2014, 5:51 am

starvingartist wrote:
1401b wrote:
Huh, I'm not an astronomer but I thought the observable universe had a radius of 13.7 billion light years, the maximum that we can see and therefore the presumed age of our universe.
Unless observable means something different than: the stuff we can see.

Space is defined by it's contents so once we get beyond the "edge" of our universe there are no more contents, therefore no more space to define, therefore no more distance therefore no "infinity."
Which is just semantics.

The idea of forever or infinity is rather pointless so I cope with it by simply assuming that if it's that far out there then there's probably nothing of interesting there or on the way there.
Meaning it's too boring to get to, either in a spaceship or in a thought experiment.

In the end I assume there isn't any infinity because there will always be some kind of change or another that we'll view as demarcations.

The concept of infinity (imo) is just mental masturbation -it's fun to think about.


the light that we see when we look as far away as we can look (13.7 billion light years) has been travelling for 13.7 billion years--and during those many eons, the universe the light was travelling through has been expanding--so even though the light has been travelling for 13.7 years and therefore we say it came from 13.7 billion light years away, the universe that it travelled through in that time frame expanded to the size of 93 billion light years across. relativity is a funny thing when you're talking about extreme speeds (like light speed) and huge distances (like billions of light years).


Okay...

The farther away something is from us in intergalacitc space the faster it is moving away from us.

So the farthest objects (the ones at the edge of our perception) are the fastest things. And they are moving at just under the speed of light (call it "AT the speed of light").

So the farthest objects are moving at the speed of light. And we precieve them as being at a position X lightyears away ( the unit of measurment of distance just happens to be in the units of time it take light to travel the distance).

So if we see the object at X light years away that means that the light took X years to reach us. Which means that the object itsself must have been traveling away from us for those same X number of years. And it was traveling at the speed of light. So the location of the object today is X light years beyond where we see it today. Where we see it today is X lightyears away- it has traveled X LYs beyond that in the same direction. So it is now 2X LYs away from us.

So the objects we see at the edge of the visible universe that appear to be 13.7 ( call it '14') billion lightyears away are all in fact 28 billion light years away. So the radius of the known universe is really 28 billion light years. So the diameter of the universe is 56 billion light years. That still doesnt add up to 93 billion light years.

So what gives?



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20 May 2014, 5:59 am

MrOddBall wrote:
So basically the universe has already ended but we're catching up to it ?


No.

The universe is expanding faster than the speed of light.

Which means we are all moving faster than light. And according to Einstein when you move faster than light you are going backward in time.


So for the last 14 billion years the whole universe has been ageing backwards.

The big bang was actually the end of the universe. And we are all now moving backward in time to the universe's unknown beginning.


In essence: all of the galaxies in the universe are solid matter being flushed down a comode by God. But since time is moving backwards it APPEARS that all matter is being expelled from the vortex rather than being sucked into the vortex.