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space never ends?


turnbui
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I was once told that space is infinite? Should I just accept this as fact? Is it true? Surely, vast as it undoubtably is, it must end? I guess if so the next question would be what is after it?

Can someone explain please?

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Surely, vast as it undoubtably is, it must end?

Think of it this way - imagine yourself as an ant living on the circumfrence of a wheel. The space you live in is clearly finite, yet it has no end ... and the question as to what's "outside" makes no sense as it's completely out of your frame of reference.

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Recently they've found that space is (almost) flat with some satellites (I've totally forgotten which ones, if you're desperate to know I'll look it up) compared with in the 80's and 90's where we thought space was a bumpy horse saddle shape of even a sphere.

So it does probably have an "edge" but keep in mind space is expanding, so beyond the edge is perhaps nothing, no time, no space, no dimensions. Of course there's the exciting (and reasonably likely) possibility of a 'multiverse' so maybe you could look from the edge out onto someone elses universe.

It's of course all hypothesis, no one knows for sure, but I was also told as a child at school that space was infinite. The odds of that seem very low to me as infinity is a difficult thing to work with, think about it mathmatically, anything multiplied by infinity is also infinity, for example if i had one garden variety frozen pea and it weighs one gram its plausible however if I somehow found a way to grow infinte peas then those peas would have an infinite amount of weight(one gram multiplied by infinity), and be infinitley big (0.3cm wide + high multipled by infinity).

Hope that helps,

Mark

PS don't accept things as fact without them being backed up, especially on such a bold claim. You do right to question it.

Edited by mark84
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So it does probably have an "edge" but keep in mind space is expanding, so beyond the edge is perhaps nothing, no time, no space, no dimensions.

That's got me thinking. If you got on a very fast space ship which traveled faster than the "edge" eventually you'd but out in the no time no space bit, but then you wouldn't be because you are matter hence there would some mass there and that would mean there would have to be time too..

This is a bit confusing

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I think space (or spacetime?) is the surface of a huge, expanding sphere (as a 3D representation). The sphere is big enough so that space appears flat in our observable part of the universe (Just as the surface of the earth appears (almost) flat in the area you can see).

This would explain why is has no end. It would also explain the expansion as it's the "sphere" that's expanding. It also explains why the expansion is accelerating. The radius of the sphere expands linear but the surface area increases exponentially.

And Gravity is dimples in that surface where the sphere hasn't quite expanded as much yet.

Now where is my Nobel Prize? :)

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If you want to pursue this further, Astronomy Cast is a fantastic resource, a weekly podcast looking at all things astronomical. Pamela Gay has a really good way of explaining even complex ideas (and a wonderfully attractive voice). This episode Astronomy Cast - Ep. 78: What is the Shape of the Universe? looks at the shape of the universe and the various theories which exist about it.

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Sounds good, thanks Roger.

Travelling to the edge would be impossible most likely, as light is already travelling out there at the speed of light, therefore space is expanding at that rate, so it's already expanding at the speed of light, which creates an issue as it's thought it's impossible for matter to travel faster than this speed (without wormholes or some way to teleport).

There's an interesting point about relativity too, even if you were to teleport near the edge, and travel at lightspeed in your super-space ship light would still accelerate away from you at it's full speed (unlike a bullet which if you went fast enough it's possible to catch up light will always travel at lightspeed- 186,000 miles per second- away from you).

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If I were an ant then man would be very big - however I were a blue wale then man would be very small.

Sometimes when looking at things you have to resolve yourself to the fact that unless you can look at it from a different perspective you can not judge at all what it is you are looking at.

It is all well and good for Man to come up with theories and prove things out using credible math and using data that has some weight.

But - we are on a tiny planet revolving around an unremarkable star in a galaxy one of trillions.

Our understanding of physics can only be limited to the experiences and observations from a somehwat limited point of view.

A point well made in the film men in black at the end.

Until we get of this rock and see how other systems work and the differences we will encounter relating to how time, light, elements and mass works elsewhere - we will always be be chasing a tail that has long been cut off....

Chris

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Over my lifetime I have often pondered these very questions, usually only resulting in a headache.

If I were an ant then man would be very big - however I were a blue wale then man would be very small.

Along this thought, has anyone (by anyone I mean a real scientist with more MB memory and processing power than I) considered that we may, on someone elses scale be living on some subatomic particle or similar? That is, in a similar way to what we believe to be an electron, someone else could see our sun as their electron in their model? Therefore our galaxy is just an atom?

Does Stephen Hawking come here often??

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If I were an ant then man would be very big - however I were a blue wale then man would be very small.

Sometimes when looking at things you have to resolve yourself to the fact that unless you can look at it from a different perspective you can not judge at all what it is you are looking at.

It is all well and good for Man to come up with theories and prove things out using credible math and using data that has some weight.

But - we are on a tiny planet revolving around an unremarkable star in a galaxy one of trillions.

Our understanding of physics can only be limited to the experiences and observations from a somehwat limited point of view.

A point well made in the film men in black at the end.

Until we get of this rock and see how other systems work and the differences we will encounter relating to how time, light, elements and mass works elsewhere - we will always be be chasing a tail that has long been cut off....

Chris

All of our physical theories, particularly when it comes to cosmology, assume that the laws of physics are the same everywhere in the universe. That's consistent with observations to date, and there's no evidence to suggest otherwise. If that weren't the case, then any attempts to understand the universe would be futile, as you suggest.

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Along this thought, has anyone (by anyone I mean a real scientist with more MB memory and processing power than I) considered that we may, on someone elses scale be living on some subatomic particle or similar? That is, in a similar way to what we believe to be an electron, someone else could see our sun as their electron in their model? Therefore our galaxy is just an atom?

I did actually wonder exactly that. (though I'm not a scientist).

But the similarity of the basic atom model and a solar system is definitely there.

But that goes inwards as well as outwards. We could be living on someone's atom. But there could also be someone living on our atoms. and so on... infinite regression.

It's all a matter of scale.

Same with time. What seems billions of years to us could be mere seconds for others. I sometimes imagine the universe as someone else's fireworks. Initial period of inflation, then star birth, "galaxies" form and so on. (dark matter would be the atmosphere the fireworks are launched in :)). For the fireworks observer it's all over in a few seconds. They would be totally unaware that life has evolved on tiny little grains inside their fireworks in what seems billions of years to them.... :)

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All of our physical theories, particularly when it comes to cosmology, assume that the laws of physics are the same everywhere in the universe. That's consistent with observations to date, and there's no evidence to suggest otherwise. If that weren't the case, then any attempts to understand the universe would be futile, as you suggest.

Indeed that is true - just like when all evidence pointed to the earth being flat - it being the center of the universe.....

If I stood you within 1cm of an elephants side - what would you see and what would you describe as fact?

Would you see its tail - or its trunk or would you just see some thick grainy hide with a small amount of hair poking through ?

Chris

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Agreed... but at the same time, you either have to go with the best available evidence at the time and make a judgement about what you believe to be true (accepting that you might be proved wrong), or you give up trying because you can never truly know.

It is plausible and consistent that a big bang occurred, and that since our universe then shares a common source, it should be governed by the same laws. On the other hand, that wouldn't stop our universe being one of many, which are ruled by different laws and constants... maybe ours is the only configuration which allows the formation of matter at all, for instance :)

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Agreed... but at the same time, you either have to go with the best available evidence at the time and make a judgement about what you believe to be true (accepting that you might be proved wrong), or you give up trying because you can never truly know.

It is plausible and consistent that a big bang occurred, and that since our universe then shares a common source, it should be governed by the same laws. On the other hand, that wouldn't stop our universe being one of many, which are ruled by different laws and constants... maybe ours is the only configuration which allows the formation of matter at all, for instance :)

Indeed - but as my sig suggests, we are somewhere caught in the middle of our understanding.

We have spent billions if not trillions (probably the true cost) building a machine to prove a particle we suspect exists - for what purpose ?

When we could have funded a programme of manned deep space missions... the technology is there and there are people willing to go into space...and take a good gander :)

Edited by Space Bat
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