Size of the universe
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01-07-2013, 02:11 PM
RE: Size of the universe
I get that we're seeing them as they were, not as they are. But if we take the big bang as a given, don't we also conclude that these stars and galaxies were 28 billion miles or more away from us when the light that is finally reaching us began its journey in our direction?

I know that my question betrays my ignorance on the subject, but that ignorance is what I am trying to cure.
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01-07-2013, 02:15 PM
RE: Size of the universe
I googled the size of the universe and saw references to galaxies that are 30 billion light years away or more. So even if we were to assume galaxy A is traveling away from its origin point at the speed of light, and we were traveling away from the same origin point in the opposite direction at the speed of light, our relative speeds are twice the speed of light... so we should not be more than 28 billion light years away from each other. But we are. How?
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01-07-2013, 02:29 PM
RE: Size of the universe
(01-07-2013 02:15 PM)TwoCultSurvivor Wrote:  I googled the size of the universe and saw references to galaxies that are 30 billion light years away or more. So even if we were to assume galaxy A is traveling away from its origin point at the speed of light, and we were traveling away from the same origin point in the opposite direction at the speed of light, our relative speeds are twice the speed of light... so we should not be more than 28 billion light years away from each other. But we are. How?

Relativity.

No - that's it.

You can't simply treat it as, "we are going lightspeed one direction, they are going lightspeed the other direction, in 14 billion years we move 14 billion light years one way, they move 14 billion light years the other way, therefore 28 billion light years".

(01-07-2013 02:15 PM)TwoCultSurvivor Wrote:  ... our relative speeds are twice the speed of light ...

This is completely wrong. Relative speeds cannot be greater than that of light. Taking that as velocity, perceptions of distance must therefore vary. That's what the theory of relativity is.
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01-07-2013, 02:41 PM
RE: Size of the universe
Is there an emoticon for exploding heads?
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01-07-2013, 03:08 PM
RE: Size of the universe
(01-07-2013 01:54 PM)ridethespiral Wrote:  Yeah 28 = 14 x 2

Also we are seeing them as they where not as they are. Looking back toward the center of the universe is like looking back in time.

Looking in any direction in the universe is looking back in time.

There is no center to look toward.

Skepticism is not a position; it is an approach to claims.
Science is not a subject, but a method.
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01-07-2013, 03:24 PM
RE: Size of the universe
(01-07-2013 03:08 PM)Chas Wrote:  
(01-07-2013 01:54 PM)ridethespiral Wrote:  Yeah 28 = 14 x 2

Also we are seeing them as they where not as they are. Looking back toward the center of the universe is like looking back in time.

Looking in any direction in the universe is looking back in time.

There is no center to look toward.

I'm not sure I follow? Do we not point our telescopes toward the point of the big bang to observe the early radiation patterns of the universe? I get that there is no matter there anymore and that all galaxies are moving away from each other (or at least the various local clusters are moving away from each other) at an ever increasing rate. Looking at Andromeda I'm looking back 2.5 million years, as Andromeda is relatively close (and actually on a collision course with the milkyway), but yes anywhere I look I am seeing what was....The sun will die 8 minutes before I know about it, etc.

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01-07-2013, 03:36 PM
RE: Size of the universe
Ok. So.

How does relativity explain the speed with which stars and galaxies have moved away from each other at a speed that is faster than light?

Does my question make sense? Again, I am professing my ignorance, so please don't think I'm looking for a gotcha! question. I'm just lost.

My puny mind says nothing in the observable universe should be any more than 28 billion light years away, and that's assuming we're at one edge of the balloon and the other object (galaxy) is waaaayyyyyy over on the other edge. And then, how did they get that far away so fast? Do galaxies travel faster than the speed of light?
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01-07-2013, 03:37 PM
RE: Size of the universe
Expansion:

Consider this: Delvin is driving east from Cityville at 60 mph, while Naven is driving west from Cityville also doing 60 mph. In one hour they should be 120 miles from each other, right? Not with expansion. Picture the highway itself stretching as they move along it. Even though their speed limit allowed them to each only move 60 miles, they are each now 90 miles from Cityville due to the expansion of the ground. (I chose 30 mph as an arbitrary rate of expansion, actual results may vary.)

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01-07-2013, 03:39 PM
RE: Size of the universe
In real life, we don’t have man-made objects far enough away to communicate with us across the necessary distances to measure curvature. Even if we did, it would take billions of years to do it, which is a disheartening way to attempt to do science. But we have light signals from when the Universe was just 380,000 years old, that tell us what the Universe is like 46 billion light years away.

Looking for a straightforward answer, other than what was covered - ain't finding it. Big Grin

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01-07-2013, 03:40 PM
RE: Size of the universe
Part of the reason I ask all this is, if a criticism of creation is that light from distant stars takes x number of years to reach earth, and that is inconsistent with the age of the earth as calculated by Biblical chronology, how do WE (atheists) account for our ability to see stars and galaxies that are so far away that the universe is not even old enough for the light from those galaxies to have reached us yet?
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