Does the Universe extend equally in all directions?

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Jay Ramsey

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Jay Ramsey  asked the Naked Scientists:
   Dear Naked Scientists,
I understand that astronomers will look out into space to understand what happened in our early universe.  And that the farther out into space they look, the earlier in time they are looking.  But something there doesn't make sense, because the greater the distance you look out into space, the further back in time you are looking.  And at some point you should be able to see the beginning of the universe represented by a sphere-shaped periphery.  But this seems like a paradox, because didn't the universe start out as a single point with light and energy (and eventually mass) moving outward and not a giant sphere-shaped periphery?
Love the show!
Jay in Cedar Falls, Iowa    USA
What do you think?
« Last Edit: 08/09/2011 11:30:03 by _system »


Johann Mahne

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Does the Universe extend equally in all directions?
« Reply #1 on: 16/09/2011 09:26:38 »
 There is no space time outside the universe.
This is because as the universe expands it drags space time along with it.
So that is why scientists like Hawking says that we cannot speak of a universe with boundaries, and therefore there cannot be a center of the universe or an edge.
 What this means,Jay,is that there is no answer for your question.


Offline yor_on

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Does the Universe extend equally in all directions?
« Reply #2 on: 16/09/2011 10:05:14 »
This universe is defined through distance. Even space contains that, and 'gravity'.

Gravity is what shapes the distances we see, as well as it defines 'time' for you, observing some distant point. But the measurement will also be a product of your relative motion and mass, relative what you measure.

And is coupled to that same gravity, the only exception to that being a uniform motion that might be defined as a absence of gravitational influences, excepting those the mass you have intrinsically can 'produce'. It's a tricky subject though because uniform motion will also be able to produce a time dilation and Lorentz contraction, even if defined as having no 'gravity' acting on it, excepting what is moving in that geodesic.

So it's not only gravity and accelerations that couples to the different 'clocks' you find observing, also uniform motion. And they all change your measurements. That makes 'scales', and so 'distances' a very subtle subject of discussion. We might still be that 'point' in some for us imperceivable manner. Although what I write here seems to contradict all we see I think string theory might agree with it, at least some of its assumptions in where we might be a brane.

You possibly could think of it as a game, or a static numberspace, in where the numbers change due to some internal logic, describing a SpaceTime, unique to each one of us. Using, as well as creating, what we call the arrow of time.

If we define time as being a 'change' then that is the 'point', because there needs to be a change of state for SpaceTime to exist. With the 'arrow' we have becoming a later development, intimately connected to the 'room' we exist in, energy distribution, mass and relative motion. So change is what time is about, and that might be represented by a number space changing its values, dependent/relative the observer.
« Last Edit: 16/09/2011 10:32:21 by yor_on »
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